LIBRARY
OF THE
MASSACHUSETTS
AGRICULTURAL
^' LEGE
Sou
/903-/9/O
DATE DUE
Clt£
Hhu
IJTBKA KY of tl
MAR17B13
State of Connecticut
REPORT
OF
The Connecticut Agricultural
Experiment Station
FOR THE YEAR 1903
PART IV.
REPORT OF THE STATION BOTANIST
CONNECTICUT
AGRICULTURAL EXPERIMENT
STATION
REPORT OF THE BOTANIST
G. P. CLINTON, S.D,
J903
C7^ 1^03-1916
EXPLANATION OF COLORTYPE
Figures about natural size
1. Leaf Blight on Quincq ; see page ...... 352
2. " Cedar Apple " on Cedar branch ; seepage . .' . . 301
3. Red Knot on bark of Kcelreuteria ; see page .... 328
4. Loose Smut in spike of Barley ; see page .... 306
5. Anthracnose on leaf of Chestnut; seepage . . . . 315
6. Black Dot on leaflets of Crimson Clover ; see page . . 316
7. Curl on Peach leaf ; see page ....... 340
8. Leaf Spot on leaflet of Strawberry ; see page . . . 360
g. Orange Rust on leaflets of Blackberry ; see page . . . 309
10. Powdery Mildew on leaf of Indian Currant ; see page . . 327
11. Leaf Spot as seen on upper surface of Cherry leaf ; see page . 314
12. Downy Mildew on Lima Bean Pod ; see page . . . . 307
13. Leaf Blight on Corn ; see page ...... 317
DISEASES OF PLANTS CULTIVATED IN CONNECTICUT. 2/9
REPORT OF THE BOTANIST. ,
DISEASES OF PLANTS CULTIVATED IN CON-
NECTICUT.
By G. p. Clinton.
Introduction. Since 1889 the botanists* connected with the
Experiment Station have made studies of many of the troubles
that assail our cultivated plants. The results of these inves-
tigations have been published in the annual reports or in bul-
letins, as short notes or as more extended treatises. During the
past two seasons, the writer has made a special effort to gather
together from different parts of the state information on all of
the diseases of our cultivated plants, to use, with the previous
data, as the basis of the present report. The cultivated plants of
Connecticut fall under four general heads: viz., i. The general
farm crops, 2. The horticultural or fruit crops, 3. The market
garden crops, 4. The ornamental plants. Often the grower is
interested only in one of these lines, but usually he specializes
less and includes at least two. An attempt has been made to
cover all of these industries in the notes reported.
Causes.
While the troubles to be discussed here are chiefly those pro-
duced by fungi, it will be well to note briefly the chief causes
of injuries to plants. We can group these, somewhat arbi-
trarily, under the following four heads :
I. Mechanical Injuries. Under this head may be placed
such injuries as result from some sudden mutilation of the plant.
Damage by wind storms is of this character, and we had a good
illustration of the injurious nature of such an agent to our fruit
and shade trees in the gale of last September. Lightning is
sometimes the cause of injury to shade or forest trees, opening
the way, also, for future decay by timber-rotting fungi. Forest
fires, while not occurring often on a large scale in this state,
still, sometimes do considerable damage to local wood lots.
Animals are agents of more or less damage to plants. Birds
* Prof. R. Thaxter, 1889-gi ; Dr. W. C. Sturgis, 1891-1901.
19
280 CONNECTICUT EXPERIMENT STATION REPORT, I903.
destroy considerable grain and fruit. Mice and rabbits often
injure fruit trees by girdling. Sometimes cattle go where
not wanted, with destructive results. In towns the injury to
our street trees by horses is very evident. See Report 1900, p.
332. Man, himself, is often a mutilator under some conditions
when installing city improvements.
2. Insect Injuries. These might be classed under animal
injuries, but the damage insects cause in the way of chewing,
sucking and stinging cultivated plants is so great that they
deserve notice by themselves. It is not the purpose to treat
of these here since the entomological reports issued from time
to time by the Station deal with this subject. Since the fungi
are occasionally classified by some persons as "bugs," I wish
to call attention to the fact that insects as agents of injury to
plants are entirely different from f^l,ngi as disease-producers.
Usually the troubles caused by these two agents can be distin*-
guished readily. Holes in' the leaves or wood may generally
be attributed to insects, dead spots to. the fungi. While insects
by their stinga often cause a morbid growth, they are not true
agents of decay as are the fungi and bacteria. The presence
of an insect at the place of injury or of the spore stage of a
fungus usually indicates the responsible agent.
3. Physiological Troubles. These are often obscure as to
cause, being due to some disturbance of the natural surround-
ings of the plants, and are generally progressive in nature.
Different conditions produce different troubles and as yet com-
paratively few have been studied or even noted. Cold weather
is not an uncommon cause of trouble in plants. Injuries from
this source usually result from a mild, late fall (in which the
wood of plants fails to ripen thoroughly) followed by a sud-
den severe freeze, as that of December 9, 1902 ; or from an
unusually severe winter, as has been the present ; or from mild,
open winter weather, inducing a flow of sap, followed by freez-
ing weather; or from an early spring, inducing premature
blossoming, followed by killing frosts, as illustrated somewhat
by the spring of 1902. The resulting injuries may be classed
partially as mechanical, as the sudden death of the fruit buds,
but chiefly as physiological. As yet we do not sufficiently know
what troubles result from severe but not fatal injuries to the
roots, wood and cambium. The primary effects of the cold
CAUSES OF PLANT INJURIES. 28 I
are often manifest at once as a distinct injury, the secondary-
effects may be obscured in later developments, possibly cover-
ing a number of years. The effects of the sudden freeze of
December 9, 1902, became evident at once or during the past
year by the partial destruction of privet hedges ; by the almost
total destruction of peach fruit buds, also by the death of some
twigs and slight injury to the wood ; by the girdled areas in the
bark at the base of apple trees ; and, in some nurseries, by
the severe injury or death of the wood of young fruit trees,
especially apples, without apparent injury to the bark or cam-
bium. During the past severe winter, the injury, so far as
observed, has been the partial destruction of the peach fruit
buds and the very great injury, or even death in some orchards,
of the wood, showing by its darkening -color down to the
snow line. Heat by affecting transpiration of moisture may
produce wilting of foliage or tip burn ; in greenhouses it
may even burn spots in the leaves, probably in connection
with imperfect glass or drops of water. Water when present
in excess in the soil shuts out the proper circulation of air and
thus causes a sickly yellowish plant growth or drowns it out
entirely. In the shape of rain and dew it is the chief factor
in the spreading of fungous diseases. Fertilizers, when used
carelessly, sometimes burn the foliage, injure the roots or often
kill the germinating seedlings. On the other hand, the lack
of the proper elements of fertility in the soil manifests itself in a
scanty or sickly plant growth. Ensyms, or chemical ferments,
produced in plants through a disturbance of their normal activi-
ties and causing a diseased condition of the tissues containing
them, are now given as the cause of such obscure troubles as
peach yellows, calico tobacco, yellows of asters, etc. Such
troubles are sometimes transmitted and are said to be produced
by "running out of the stock," by unfavorable mechanical con-
ditions in the soil, etc.
4. Fungous Diseases. It is the comparatively few physio-
logical troubles and the very numerous fungous diseases that
this article treats. The latter have, as the agents, what are
commonly called parasitic fungi. A fungus is a plant as truly
as are the flowering plants, but it is low down in the vegetable
kingdom, lower even than is the insect in the animal world.
Let us consider more fully the nature of these fungi, their
282 CONNECTICUT EXPERIMENT STATION REPORT, I903.
effect upon vegetation as producers of disease, and the methods
employed in combating them. [See Reports 1889, pp. 1.27-9;
1897, p. 182; 1900, p. 255.]
Parasitic Fungi.
Nature of Fungi. As has just been stated, fungi are low
in the plant kingdom, in fact, among the lowest and conse-
quently of rather simple structure. Many of them are micro-
scopic in size, while the largest are represented by the shelf
fungi, toadstools and puffballs. They differ from the higher
groups (the algae, mosses, ferns and flowering plants) in that
they lack chlorophyll or the green coloring matter that enables
these other plants to manufacture their food directly out of
the air, water and soil. They must in consequence, like ani-
mals, obtain their food already in an organized state from
organic matter. When they obtain this from dead vegetable
or animal matter, they are known as saprophytes, examples of
which are the common household molds, puffballs and toad-
stools. When they get it from the living plant, or animal
occasionally, they produce disease and are called parasitic ftmgi,
as the various blights, rusts, smuts, mildews, leaf spots, etc.
The line separating parasitic and saprophytic fungi is not very
sharply marked, for many parasites have stages that are sapro-
phytic, and some species, ordinarily saprophytes, may under cer-
tain conditions act as parasites. In general two structural parts
are recognized in fungi ; namely, the mycelium and the spores.
Mycelium. This is the vegetative part of the fungus (cor-
responding in function, in a general way, to the roots, stems
and leaves of the higher plants) since it is largely concerned
in gathering food. As stated before, it does not manufacture
this food but gets it directly from the host (the plant or animal
upon which it grows), either from food intended for the latter's
use, or as the result of the disorganization of the plant's cells
or cell contents by enzyms, or through the formation of morbid
plant growths. The disease thus induced may be very local
or widespread and it may become evident at once or only after
considerable time.'
In general the m3^celium consists of microscopic threads,
becoming more or less branched. The gross aspect is shown
by the spawn that ramifies through the soil from the base of
NATURE AND STRUCTURE OF FUNGI. 283
the toadstool. These threads are divided more or less by cross
partitions into cells which are usually elongated. Generally
the threads of the mycelium ramify loosely through the sub-
stratum but sometimes they are compacted into masses. The
cells when young are filled with protoplasmic and other con-
tents but with age the contents become limited to the walls or
to scattered granules. The mycelium is generally colorless.
Sojnetimes it is confined almost entirely to the exterior of the
host, only sending short food-gathering branches, haustoria,
within, as with the powdery mildews ; but usually this condi-
tion is reversed and the mycelium is entirely concealed within
the host, running between or often directly into the plant cells,
and becoming evident on the exterior only when specially modi-
fied parts give rise to the spore stage. As a rule, then, the
mycelium is not very evident or characteristic in the different
fungi.
Spores. These are the reproductive bodies and, roughly
speaking, correspond in function to the seeds of the flowering
plants. They are formed on or from modified threads of the
mycelium, usually at or on the surface of the host. While
microscopic in size, the spores are usually produced in such
abundance as to be evident to the naked eye. Thus in the
rusts and smuts the reddish or blackish outbreaks are made up
entirely of these bodies. Often they consist of a single cell,
varying in shape, size and character of the wall in different
species ; not infrequently they are composed of two to many
cells variously combined, of which, occasionally, only part are
fertile. So great are these variations that those of each species
usually have some individuality by which they can be recog-
nized and it is chiefly upon these spore differences that the
fungi are classified.
Very curiously each fungus generally has more than one,
kind of spores, sometimes as many as four or five kinds. These
spores are of two types, summer and winter spores. The
■summer spores are usually thin-walled, germinate readily and
are produced on the external parts of the host in great abun-
dance, to be easily scattered. Their object is to spread the
disease to the same or other plants during the growing season.
The winter spores, on the other hand, are not produced so
abundantly, are often buried more securely within the tissues,
284 CONNECTICUT EXPERIMENT STATION REPORT, I9O3.
and if not thick-walled are formed within sacs and receptacles
that protect them to a great degree from moisture and cold.
Frequently they will not germinate until the following spring.
Their evident function is to carry the fungus over the unfavor-
able period of winter weather. Mycelium in the perennial parts
of the plant, also, may serve this same purpose, as in the case of
the orange rust of blackberry.
The different kinds of spores are produced at different
times of the year, usually the summer spores in spring and
summer and the winter spores in summer and fall. Thus, the
red (summer) stage of rusts precedes the black (winter) stage.
This peculiarity is carried a step further when we find one
spore stage developing parasitically and another saprophytically.
Thus, in apple scab the summer spore stage exists as the "scab"
of the living leaves and fruit while the winter stage develops
on the dead leaves in the fall and following spring. The separa-
tion of the spore stages, however, becomes widest when they
occur on entirely different host plants, one producing the other.
Such is the case of the cedar-apple rusts and the barberry-
wheat rust.
To solve the complete life history of a fungus, therefore,
often becomes a considerable problem. It is because of these
complications that botanists have often described different stages
of the same fungus as distinct species. There are many para-
sitic fungi of which only the summer spore stages are known
but which are suspected of having saprophytic winter spore
stages, since detailed study of related forms has often brought
these to light.
Fungi infect their host through the germination of the spores.
Moisture in the shape of rain or dew is necessary to induce this.
Usually the germination must take place on certain parts of
the plant in order to secure entrance. Often the parts per-
mitting infection are quite localized but more often it is a ques-
tion of the tissues being in a young state and thus easy of
penetration. The common method of infection is for the spore
to send out a short germ thread which enters the plant
through the stomates (breathing spores) or else bores directly
through the tissues. Once inside, this thread, by growth, gives
rise to the extended mycelium. Comparatively few spores meet
conditions that insure infection of the host, hence the neces-
sity to the fungus of great numbers of spores.
NATURE AND STRUCTURE OF FUNGI. 285
Relation to weather. We have remarked on the importance
of moisture to germination of spores and consequent infection
of hosts. The character of the weather thus bears important
relation to the spread of plant diseases, especially with certain
kinds at special times. It is not the amount of rain that falls
that is most important but the time it takes. For example,
a few days of moist weather with comparatively little rain but
also with little sunshine to dry away the moisture from the
foliage is evidently more favorable for spreading these troubles
than a violent rain storm followed the same day by bright sun-
shine. Cloudy weather, by hindering evaporation of the water
'transpired by the leaves, may aid in the spread of disease.
In its relation to different diseases of plants, the season
of the moist weather is very important. For instance, a
rainy April-May period is very favorable for apple rust; a
cold, moist May or June aids decidedly the introduction and
spread of apple or pear scab. The fruit grower dreads moist
weather during the ripening and harvesting period of his peach
and plum crop, since brown rot flourishes chiefly at this time.
The market gardener is specially anxious about the rainy week
that may come in July or August and blight his potato vines,
and which, if followed with additional rainy weather, is likely
to rot the tubers ; or of wet August and September weather
that produces stem rot in his onions. The downy mildews are
especially lovers of moisture, and so the musk melons and
cucumbers have suffered from one of these troubles during the
past three years, because of their moist summers.
Water affects the spread of fungous diseases in three ways :
First, many fungi, especially the stages producing thin-walled,
ephemeral spores, produce these only or most vigorously during
moist weather. Second, the rain, in a measure, acts as a distrib-
uting agent, washing the spores over different parts of the
plant. Third, water, as has been stated before, is needed for
the germination of the spores.
Injury and Loss. It is evident from what has been written
that parasitic fungi often become agents of serious disease in
plants and thus cause greater or less financial loss to the hus-
bandman. It is not the intention to present an array of figures
showing the losses caused by these parasites in Connecticut, for
startling as these might look, they are not nearly so suggestive
286 CONNECTICUT EXPERIMENT STATION REPORT^ I903.
to the grower as some personal recollection he may have of
local losses. Occasionally one hears the remark, "Fungous
troubles are much worse than formerly. We never used to be
bothered so by them." Very often this statement is incited by a
season that has been especially favorable for such troubles, or
is drawn forth by an unusual personal loss. Where plant grow-
ing is intensified, as it is in Connecticut, we may reasonably
expect more trouble from fungous pests than occurred in the
earlier days when farms were more scattered, importations
limited and crops less specialized. We should bear in mind,
however, that agitation and information now make losses seem
more prominent than formerly, since then the grower knew less •
of the why and wherefore of his troubles, attributing them, per-
haps, wholly to season and luck.
Some of the pests causing serious loss during recent years may
be briefly mentioned. Brown rot of peaches and plums is always
present at harvest time, some seasons becoming so prevalent that
it sweeps away a large part of the profits in a few days. The
past year produced a small peach crop and this accounts in part
for the small amount of rot, even in early varieties, as the fruit
of heavily laden trees always rots more or less because of the
facility for spreading the disease. Scab or black spot is another
trouble of the peach that attracts the attention of the grower, for,
while it is not primarily an agent of decay, it causes the fruit
to become second class in appearance, often smaller in size or
one-sided, and by cracking it, opens the way for decay. This
trouble seemed to be worse than usual the past season. Black
knot of plums and cherries is an old trouble that proved more
prominent than usual last year. This is one of the few fungous
diseases against which laws have been directed in some states.
Downey mildew or blight of potatoes during the past two years
has prematurely killed the vines in July or August, thus cutting
down the crops of the late varieties 25 to 50 per cent., for the
vines should have lived until killed by the September frosts.
During the past season rot of the tubers, following the blight,
added to the loss and attracted considerable attention among the
growers. Stem rot of the White Globe onions has now been
very bad for two years and has almost discouraged the grow-
ing of this popular and otherwise very profitable variety. In
the vicinity of Green's Farms and Southport in 1902, the loss
CLASSIFICATION OF FUNGI. 28/
was reported to be in the vicinity of $50,000, and last year
some growers, after marketing part of the crop with returns
little greater than the freight charges, threw away the remain-
der. The Downy Mildew and other troubles of the musk melon
have proved so serious during recent years that many have
given up growing this plant. The greenhouse man has his
special troubles with the leaf spot of violets, rusts of carnation
and chrysanthemum, mildew and leaf spot of rose and the vari-
ous stem rots, and sometimes the local loss caused by one or
more of these fungi becomes considerable.
Classification. Botanists have classified the fungi under
various groups according to their relationships. Some of these
groups contain only forms that are of little economic impor-
tance, but the chief divisions all contain at least some important
parasitic forms. The scientific name of a plant conveys some
idea of its nature and relationships. Dr. Sturgis in his Litera-
ture of Fungus Diseases [see Reports 1893, p. 253 ; 1900,
255] aimed to apply the common names somewhat similarly, so
that the terms rust, smut, blight are applied only to certain
related forms and not used indiscriminately. Since in the fol-
lowing notes this plan has been largely followed, it may be
profitable to discuss briefly a popular classification of these
chief groups :
Slime Molds. Some scientists place these forms with the
animals, and strictly considered they are related to rather than a
group of true fungi. Ordinarily they occur as saprophytes that
are found chiefly on decaying stumps in the woods during
moist weather. At first they consist of brightly colored naked
masses of protoplasm that ooze out in jelly-like masses on the
wood, but in a dry atmosphere these soon change into clustered
spore-bearing bodies. They are mentioned here because at least
two forms are parasitic; viz., club-root of cruciferous plants
and crown-gall of fruit trees. In both of these diseases there
is a morbid growth of the infected tissues of the host but there
is no evidence to the naked eye of the causal agent. See Plates
XV, a ; XXIV, b.
Bacteria. These, also, are hardly true fungi but are very
closely related to the lowest forms and for all practical pur-
poses may be considered with them here. Bacteria as agents
of contagious diseases in animals, especially in man, are
288 CONNECTICUT EXPERIMENT STATION REPORT, I903.
recognized as very important organisms. While the diseases
produced in plants are comparatively few, these are usually of
importance and are very properly designated blights. They
cause the death of the tissues invaded and these often assume
a semi-water-soaked appearance. No sign of the bacteria is
seen save occasionally in the sticky slime that oozes out on the
surface. Examining this under the microscope, we see myriads
of these smallest and simplest of living organisms — mere
rounded or elongated cells too small to be seen save with the
highest powers. Insects are very important factors in the dis-
tribution of these germs and they are among the most difficult
troubles to control. Prominent examples are pear blight, bean
leaf blight [Plate XIII, d], blight or wilt of cucurbits [Plate
XXVI, a] and wet rot of potatoes [Plate XXII, a]. Some
bacteria are useful, as soil bacteria, those producing root tubercles
on leguminous plants, those giving flavor and aroma to
butter, etc.
Thread Fungi (including Downy Mildews). This group
includes a miscellaneous lot of fungi of which only the Downy
Mildews are of economic importance in this state. These mil-
dews are usually distinguished by the rather dense whitish
growth they form on the outside of the infected parts. See
Plate XIII, b. Examining this under the microscope, it is found
to consist of erect fertile threads having a special, often tree-like,
branching above, on the tips of which the thin-walled summer
spores are borne singly. Less commonly, these fungi form
large, thick-walled, dark colored winter spores embedded in the
tissues, from which they are liberated only by decay. Promi-
nent examples of the downy mildews are blight of potatoes
[Plate XXIII, a], downy mildew, or blight of melons and
cucumbers [Plate XVIII, b], and the downy mildews of lima
beans [Plate XIII, b], and of grapes [XVII, b].
Smuts. The smuts cause very important diseases of the
cereals, especially in the central and northwestern part of this
country. As their name indicates, they are ordinarily distin-
guished by the "smutty" outbreaks on various parts of the
host, most commonly occurring in the floral parts. Some
species, the white smuts, of which few are of economic impor-
tance, are permanently embedded in the tissues and lack this
dusty character. These outbreaks are made up entirely of the
CLASSIFICATION OF FUNGI. 289
spores. The spores are usually single cells, but may consist
of several cells united into a ball, which sometimes is covered
with a coating of sterile cells. The spores in germinating often
give rise to secondary spores, after the fashion and nature of
the yeast fungus, and these help greatly in spreading the fungus.
In the case of corn smut, for instance, these secondary spores
are capable of existing and multiplying sapropyhytically in
manure. In this state, the most injurious smuts are those of
onion, corn [Plate XVI, b], oats [XIX, e] and barley [XIII, a].
Rusts. Rust is a term often used by growers to indicate any
spotting of foliage, but as restricted here, it is applied to those
small, reddish or blackish outbreaks on leaves and stems that
are somewhat similar to the smuts but usually less dusty and
often quite firm. They form a very common and large group,
and include some of the most injurious of our parasites. In
this state, the economic species include such examples as apple
rust [Plate XI, c], oat rusts [Plate XIX, c-d], carnation [Plate
XV, b] hollyhock [XVII, d], bean [Plate XIII, e] rusts, etc.
The rusts are especially interesting because their spore forms
may occur on different hosts. Let us illustrate this with the case
of the black stem rust of oats : spermatia, inconspicuous, sup-
posed spore stage, on upper surface of barberry leaves ; I,
aecidio-spores borne on the under surface, beneath the above,
in the cluster cups ; II, or uredo-spores, forming the reddish
outbreaks on the stems of oats in early summer ; III, or teleuto-
spores, forming the black, less dusty, outbreaks on these same
stems later in the season. Some rusts possess only one or two
of these stages. In the case of the apple-leaf rust, the aecidial
or summer spores occur on the apple leaves and the teleutal or
winter spores on the cedar in the ''cedar apples."
Fleshy Fungi. These are the most conspicuous fungi, includ-
ing the toadstools, shelf fungi, puffballs, etc. The "spawn"
of the cultivated toadstool is the mycelium, and it is perhaps
chiefly by this that these fungi are carried over the winter. The
toadstool itself is the fruiting body, bearing the thin-walled
spores on the surface of the gills, that radiate out on the under
side of the cap. In the puffballs, the dusty cloud that puffs
out on pressure is composed of the spores. These forms are
largely saprophytic, getting their food from the humus of the -
soil or dead wood. Some species are parasitic on trees ; the
290 CONNECTICUT EXPERIMENT STATION REPORT, I903.
injury done to trees and timber by the mycelium, causing dry
rot, is very considerable.
Sac Fungi (including Poivdery Mildews). Under this
group come a great variety of fungi, including some of our
most destructive parasites. They are distinguished micro-
scopically by the fact that their winter spores, often eight in
number, are borne inside of sacs or asci, and these in turn are
enveloped, partially or wholly, by a special receptacle. The
powdery mildews constitute one of the most distinct and impor-
tant groups of this class. They are characterized by their
mycelium developing on the exterior of the host, showing as a
cobweb-like or cottony growth. The summer spores are pro-
duced on this in upright chains. The winter spores, asco-spores,
are formed inside the small yellowish or blackish balls, perithecia,
that can be seen with a lens, or often by the naked eye,
embedded in the mycelium. See Plate XV, c. The great varia-
tion in the character of the sac fungi is shown by the following
examples: powdery mildews of cherry [Plate XV, c], phlox
[Plate XXIV, a], and rose [Plate XXV, a] ; black knot [Plate
XXIV, c], black rot [Plate XVII, a], ergot [Plate XXV, b].
Not uncommonly the summer spore stages of this class of
fungi are serious parasites, while the winter spore stages develop
merely as saprophytes, as in the case of apple scab, bitter rot
and brown rot.
Imperfect Fungi. These are so-called because only summer
spore stages are known. They are suspected, for the most part,
to be merely stages of the sac fungi, and every once in a while
these winter stages are found, as recently in the case of bitter
rot of apples and brown rot of peaches. Under this group
come many of the leaf blights, leaf spots, anthracnoses, molds,
etc. Common examples are sooty blotch of apple [Plate XI, b],
black rot of quince, anthracnose of bean [Plate XIII, c], potato
scab [Plate XXII, c], leaf spot of violet [Plate XXVIII, d], etc.
Prevention.
It has become evident to the reader who has followed us
thus far, that the fungous troubles of Connecticut are of suf-
ficient importance to demand the efforts of the grower to lessen
their ravages. What are some of the methods that may be
employed to control them?
PREVENTION OF DISEASES CAUSED BY FUNGI. 29 1
Selection. The first requisite for good plants is Good seed,
spelled with a capital G. Aside from any physiological advan-
tage that large, plump, thoroughly matured seeds may have over
smaller shrivelled ones, the former are less likely to come from
diseased plants or to carry disease germs than are the latter.
In some cases it is desirable to know the origin of the seed, for
in the case of the grain smuts, the spores adhere mechanically
to the seed. Evidently, seed from a field free from smut is
to be preferred to that from a very smutty field, though the
seed may look as good. Potato tubers, though not strictly seed,
come under this class. Use scabby tubers and the resulting
crop will be more or less scabby, according to the season. The
same principle holds true of nursery stock. Buy of the most
reliable firms, avoid purchase from nurseries where certain
troubles are known to be bad ; inspect the stock when it comes
and discard the poor, especially if it shows knots or diseased
areas. Selection of varieties may aid in some cases to keep
down specific troubles, since it is well known that varieties vary
in susceptibility to disease. For example, in a recent visit to
a nursery, the writer saw Wealthy and Fallowater apples abun-
dantly covered with leaf rust, while all of the other varieties
in the same block of trees were free. Greenhouse growers well
know that there is wide difference among the carnations in
rusting. Our government botanists have even taken up the task
of rearing disease proof varieties to certain diseases hy selection
and breeding. Along this line, the writer recalls what was told
him by an eastern asparagus grower who was troubled with
rust. He said he noticed in a certain spot of a neighbor's
field that a few asparagus plants always remained green after
the others were dying from the rust. He obtained plants from
that place, and was gradually building up a bed to determine
if he could secure exemption from the disease by obtaining
a rust-proof variety. He may or may not succeed, but his
experiment costs him little to determine this point. Selection
of ground certainly counts in those cases where disease has
become established in the soil. A rational system of rotation
must be adopted to prevent or lessen such troubles as onion
smut, potato scab, club root, etc. Through continued use,
especially with the same crop, the soil of the greenhouse may
become infected with stem rot, drop and other fungous troubles.
292 CONNECTICUT EXPERIMENT STATION REPORT, I903.
Cleanliness. It is easier to write about ideal farm methods
than it is tO' carry them out ; nevertheless, no one will deny-
that cleanly methods are the best. Thorough culture not only
destroys weeds, conserves moisture, but it aids in the quicker
destruction of old leaves, etc., that may be harboring the dis-
ease germs of last year's crop. Refuse of the present crop,
especially when diseased, if left on the land, becomes a menace
to succeeding crops of a similar nature. When one sees a turnip
field in which the owner has very carefully gathered all of the
roots except those "clubbed," he feels confident that the
grower is helping along the trouble in the future use of that
field for a similar crop. So, too, a field left covered with anthrac-
nosed melons does not help the success of future crops. The
manure pile is a very essential feature to successful plant grow-
ing, but it should not he made a refuse pile upon which diseased
vegetable matter is dumped. It will never do any harm to
gather carefully all rotting fruit and refuse stems from the
garden or orchard at the close of the season ; it will do good,
but the place to put them is in the bonfire.
Pruning. With certain diseases, the best treatment consists
in the removal of the affected parts. In pruning pear trees for
blight, or plums for black knot, one must cut off the infected
branches so as to include all of the diseased wood. Aside from
the removal of the diseased limbs, pruning is useful by letting
in air and sunlight to aid in the rapid evaporation of moisture
and thus hinder infection from germinating spores ; it also
lessens the work of spraying, where this is done. The thinning
of fruit, when abundant, or the removal of decayed specimens,
is a common practice that aids in minimizing most rot troubles.
Greenhouse men fight many troubles, as leaf spot of violet, by
picking off the diseased leaves as fast as they appear. As many
of our greenhouse and garden troubles first get a foothold on
a few leaves, the prompt removal of these is desirable. The
place for all such refuse is the fire.
Fungicides. One of the most effective methods of fighting
many fungous diseases is by the use of fungicides. These are
prepared in such strengths that the spores adhering to the
treated parts are either killed or prevented from germinating
while the tissues of the plant are not injured. Such treatments
are made in different ways to meet the requirements of various
SPRAYING MIXTURES. 293
troubles. Seed treatment, for instance; where the seed is soaked
or sprinkled with the mixture, has been found an effective
method for preventing most of the cereal smuts. Applied to
the tubers it is one of the ways of keeping down scab of potatoes.
Soil treatment is sometimes given where the germs become
established in the ground, as in the case of onion smut and club
root, when lime and sulphur may be used.
Fungicides are most commonly applied as a spray. By means
of spray pumps, the fungicide is distributed uniformly over all
parts liable to infection as a fine mist. Upon drying, if the
fungicide contains a sediment, this serves to destroy spores that
are brought later. Spraying depends largely for its success on
preventing rather than curing disease. The man who wins with
this treatment is the one who anticipates and precedes his trouble
rather than' the one who follows along after the disease has
gained a foothold. From the above consideration, it becomes
apparent that there are two very important factors to successful
spraying; namely, it must be done always with thoroughness
and at the proper time, which varies with the disease to be
treated. A great many substances have been tried as fungicides ;
a few of the most valuable are given here. Further informa-
tion on this subject is given in Reports 1890, p. no; 1893, p.
103; 1898, p. 266, and Bulletins in, 115, 125, 142 of this
Station.
Bordeaux Mixture. 4 lbs. Copper Sulphate, 4 lbs. Fresh
Lime, 40 to 50 gals. Water. Dissolve the copper sulphate in
hot or cold water, suspending in a coarse bag. Slake the
lime in a small amount of water and then strain into the spray
barrel which is half filled with water. Dilute the copper sul-
phate to about half a barrel and then pour into the spray barrel,
stirring the mixture. If necessary, add a little water to fill the
barrel. Where large quantities are used, it is advisable to make,
stock solutions of the lime and the copper sulphate, each con-
taining I lb. to I gal. of water. The proper proportions of each
(4 gallons each per barrel) can then be used, as in the preceding
account, when needed. Bordeaux mixture is the best fungicide
and is to be used in all cases except when sediment on the
sprayed parts is objectionable. The home-made mixture is pre-
ferable to anything bought in the market ; and the dry powders
used for dusting merit little attention as yet.
294 CONNECTICUT EXPERIMENT STATION REPORT^ 1 903-
Dilute Bordeaux. 2 lbs. Copper Sulphate, 4 lbs. Fresh Lime,
40 to 50 gals. Water. This is sometimes used when there is
danger of burning the foHage by use of the stronger solution,
as in the case of peach and Japanese plums. Caution, however,
may be necessary even with this strength, especially on old
foliage. Perhaps it is most useful for the second spraying, when
necessary for peach curl.
Resin Bordeaux. 5 lbs. Resin, i Ib.-Soda lye, i pt. Fish Oil,
5 gals. Water. Dissolve the resin in the oil heated over fire;
cool and add the lye, stirring slowly; then add water and boil
until mixture will dissolve thoroughly in cold water. Use at
rate of two gallons to a barrel of Bordeaux. This makes the
Bordeaux mixture adhere better to smooth foliage and also to
last longer. It will probably be found most efficient when used
on such plants as carnations, onions, asparagus, etc.
Soda Bordeaux, i lb. Soda lye, j lbs. Copper Sulphate, 5
OS. Lime, 50 gals, zvater. Halsted, of New Jersey, gives this
as a substitute for Bordeaux when one objects to much sediment.
It requires more care in its preparation, as an excess of soda,
or too little, will burn the foliage, so the formula calls for just
enough soda to neutralize the copper, with a little lime added
to make it slightly alkaline. Selby, of Ohio, used a slightly
modified formula (4 lbs. copper sulphate, i^ to 1^4 lbs. soda
lye, 50 gals, water), which he preferred to Amm. Sol. Cop. Car.
for the late sprayings against black rot of grapes. His formula,
because of the omission of lime, leaves no sediment.
Amm. Sol. Cop. Carbonate. 5 oss. Copper Carbonate, 5
pts. Ammonia, //5 gals. Water. Dilute the ammonia, if strong,
with several volumes of water and use just enough to dissolve
the copper carbonate; then dilute with water to 45 gallons.
This fungicide is often used to replace Bordeaux when no
sediment is desired on the sprayed plants. Because it lacks this
sediment its fungicidal value is temporary and it has to be
used more frequently. There is danger of burning the foliage
if the solution is improperly prepared, so care is needed to use
just enough but not too much of the ammonia. It is most fre-
quently used in the later sprayings for bitter rot of apple, rots of
grapes and celery leaf spots.
Copper Sulphate. 3 to 4 lbs. Copper Sulphate, 45 gals.
Water. This strength is used as a winter spray, where it is
SPRAYING MIXTURES. 295
desired to kill spores (or lichens) on the limbs. A weaker
solution, I lb. to 2^0 gals., is sometimes advocated as a summer
spray for peach rot; but the writer has not tried this strength.
Potassium Sulphide, j ozs. Potassium Sulphide, lo gals.
Water. This fungicide has been found especially useful on the
powdery mildews. Because it leaves no sediment, it is also
adapted for greenhouse work in general but requires frequent
applications. A different strength has been used for sprinkling
grain to prevent smut.
Formalin. {A) i lb. (i pt.) Formalin, jo gals. Water.
(B.) I lb.' to JO gals. Water. The (A) formula is used for
prevention of grain smuts, by thoroughly sprinkling a pile of
the grain which is stirred so that all the seeds are wetted. The
grain is left in piles or sacks over night before drying or planting.
The (B.) formula is used for potato scab, the tubers being
soaked in it i^ to 2 hours. Selby, of Ohio, also recommends
its use for onion smut, the seed being sprinkled as it lies in the
drills at planting.
Corrosive Sublimate. This is sometimes used instead of
formalin for grain smuts or potato scab. In the latter case the
tubers are soaked in a solution i lb. to 50 gals, for i^ hours.
This is a poison and corrodes metals, hence care is needed in
its use.
Sulphur. In the greenhouse this is used to check the
powdery mildews. Most frequently the powder is sprinkled
over the foliage. Sometimes the fumes produced by heating
are used, but care should be exercised not to ignite the sulphur.
A better method is to mix the sulphur with oil and paint this
on the steam pipes. Sulphur is also used, sometimes with lime,
on infected land to prevent onion smut. Stewart, of New York,
recommends 100 lbs. mixed with 50 lbs. air-slaked lime per
acre, used in the drills with the seed. /
Lime. Occasionally this is put on land infested with certain
fungi. For club root of cabbages, etc., 80 bushels per acre sown
broadcast in the fall is recommended. For onion smut 75 to
125 bushels per acre drilled in with a fertilize'r drill are required.
Hot Water. For the grain smuts, soaking the seed 10 to 15
minutes in hot water at 132-5° F. is one of the most effective
preventive treatments. Where large amounts of grain are to be
treated, the cumbersomeness of the method and the trouble in
drying the grain are the chief objections against its use.
20
296 connecticut experiment station report^ ipos-
Spray Machinery.
For a general discussion of this subject and illustrations of
types of pumps, see Bulletin 125 of this Station, also Reports
1890, p. 104; 1893, pp. 74, 105; 1898, p. 266. It is purposed
here merely to mention the different kinds and indicate the field
in which they are most useful.
Atomisers. These are bellows that produce the spray from
a small cup containing the liquid at their tip. They are hard
to work for any length of time and their usefulness is confined
to the greenhouse or small beds of ornamental plants outdoors.
Powder Guns. These are used to dust dry mixtures over the
surface of plants, usually when dew is on them. They are not
of much value in fighting fungi.
Pail. Pumps. The best form is that in which the pump is
inserted in any pail and held in place by the foot while one
hand is used to pump and the other to direct the spray. These
are of value around gardens or with small fruit grown on a
limited scale. Effective pumps are likely to be expensive.
Knapsack Sprayers. There are two types ; those in which
compressed air is first pumped into a reservoir and then used
at will to force out the spray, and the common type in which
the spray is forced out directly by pumping. These are useful
on small fruit farms or in gardens where one can not use a
barrel pump mounted in a wagon. It is rather hard work to
carry one of these pumps on the b'ack and spray for any length
of time and so they are not very popular.
Barrel Pumps. When one wishes to get among plants
where there is not room for a wagon, the small barrel pump
mounted on two wheels is very handy and preferable to the
knapsack sprayers. The ordinary pump mounted in a kerosene
barrel and carried around in a cart or light wagon is the type
in most common use. The style in which the air chamber is
immersed in the barrel with only the handle protruding is now
accepted as the best. In purchasing such a pump, one should
select a durable rather than a che^p make, and one that is strong
enough to readily supply two lines of hose, each with a double
nozzle. In commercial orchards force pumps are sometimes
used in tanks of large capacity. For certain purposes, as potato
spraying, an apparatus may be fitted up with stationary nozzles.
See Report 1893, p. 75.
NOTES ON PARASITIC FUNGI. 297
Power sprayers. In these machines the power is other than
by hand. Steam is used in some cases, but such machines have
scarcely obtained a foothold in this state. The most common
type is where the power is supplied by the horses through
gearing. This makes it necessary to keep the apparatus moving,
and thus often prevents sufficient spray reaching the plants.
Recently, machines in which the force is supplied by compressed
air or by liquid carbonic acid gas have been placed on the
market and are attracting attention. As yet, a perfect and cheap
power sprayer does not seem to have been developed.
NOTES ON SPECIFIC TROUBLES.
The following notes are upon the specific troubles that have
been reported in this state. Most of them have been seen the past
two seasons. A few of the hosts, though economic, are not
grown commercially in this state. Some of the fungi, while
occurring on cultivated plants, are scarcely of economic import-
ance. One can never be sure, however, that these may not at
some time become troublesome. The few physiological troubles
that are given are distinguished in the headings by the use
of italicized common names. Specimens of all have been placed
in the Station's herbarium and special mounts of the most
important have been made for educational purposes. The hosts
are arranged alphabetically.
ALFALFA, Medicago sativa.
Leaf Spot, Pseiidopezisa Medicaginis (Lib.) Sacc. This is
a common fungous trouble of alfalfa, though not so important
in this state since the host,- apparently, can not be extensively
grown here. It shows as small reddish purple spots scattered
over the leaves, which finally become yellowish. The only time
the fungus has been reported as injurious was by Sturgis in
the Report for 1899, p. 281.
APPLE, Pints Malus.
Bitter Rot, Glomerella rufomaculans (Berk.) Sp. & von
Schr. Plate XII, c. The summer spore stage (Glceosporium
fructigenum) of this fungus is responsible for serious injury to
apples, especially during recent years in the middle west. In
Connecticut it does not seem to be nearly so troublesome. The
298 CONNECTICUT EXPERIMENT STATION REPORT, I903.
fruit often begins to rot, while yet green, early in July, and if
the season is moist from then on the trouble becomes greatly
increased, even causing serious rotting after the apples are stored.
Rotten sunken areas are formed which rapidly increase in size,
and in moist weather produce numerous pinkish fruiting pus-
tules arranged in concentric circles. The spores are viscid and
so are easily carried by insects. Recently the fungus has been
discovered on the branches, where it forms cankered areas often
at the base of the old fruit spurs. It is in these that the myce-
lium passes the winter and produces spores for general infection
another year. The winter or asco-spore stage is saprophytic
and curiously enough was observed in artificial cultures of the
fungus before found in nature. Besides the apple, this fungus
has the pear, and probably the quince, for hosts in this state.
The treatment given for apple scab, coupled with the pruning
of diseased limbs and the gathering of rotting fruit, is apparently
sufficient for Connecticut, but in more southerly states, where
the trouble is often serious, the sprayings with Bordeaux are
followed later in the season with Amm. Sol. Cop. Carbonate
(Bulls. Ill, p. 5; 142, p. 2).
Black Mold, Fumago vagans Pers. See Pear.
Black Rot, Sphaeropsis M.aloriim Pk. Plate XI, ^. One
of the most common and universal troubles of the apple is black
rot. Ordinarily this does not attack green fruit, except through
insect injuries. It is most troublesome to the summer varieties
at time of ripening and to fall and winter varieties after storage.
The apples on rotting are brown at first, but usually blacken
later, hence the common name. This fungus also occurs on
the limbs, forming depressed, reddish, dead areas, or it may
kill the young twigs by girdling. It is very common on the
leaves, forming roundish or irregular reddish brown spots ; and
in this state most of the apple leaf spot troubles seem to be
caused by it. So far only one spore stage has been found, and
this places it with the imperfect fungi. The fruiting stage
shows on the twigs as small black pustules, easily seen by the
naked eye. The pear and quince are other hosts of the fungus.
To fight this trouble, the trees should be thoroughly pruned
of all dead limbs and twigs ; the larger cankered areas, when
found, should be scraped and painted ; the trees should be
given a winter spraying, followed by the ordinary treatment for
scab. (Rep. 1893, p. 91 ; Bull. 142, p. 2.)
NOTES ON PARASITIC FUNGI. 299
Blue Mold^ PenicilUum glaucum, Lk. This common sapro-
phytic mold occasionally causes rot in storage apples. In a
fruiting condition it is easily identified by the green blue spores
that appear in clusters on the surface of the rotten fruit.
Brown Rot_, Sclerotinia fructigena (Pers.) Schrt. Occa-
sionally this causes rotting of ripe apples. It does not seem
to be specifically different from the brown rot of peach, q. v.
Crown Gall. The crown galls on the apple have about the
same appearance as those on the peach and plum, though it is not
yet definitely known if they have the same cause. They form
irregular knots or swellings at the crown or more commonly
lower down on the roots. So far, in this state, the trouble has
been seen only on young trees, chiefly nursery stock. There
is some question just what the later effect is on the tree, but
it is safest to reject all stock showing any signs of this trouble.
In 1899, Dr. Sturgis set out on the Station grounds ten young
trees affected with knot; part of these had the knots cut off,
others had knots cut off and roots then treated with copper
sulphate, and some were left with knots on. After three seasons
of growth, these trees were dug by the writer and the roots
carefully examined. Very little difference could be seen in any
of the trees at this time and the knots had spread very little,
if any. (See Report Conn. Pom. Soc. 1903, p. 43.)
European Canker, Nectria difissima Tul. Plate XII, d.
This is found usually on old and neglected trees, where it gets
started in the branches through wounds or possibly through
winter killing. As it is perennial through its mycelium, the
bark is prevented each year from forming over the wound, so
that an enlarging canker is formed showing the annual layers
of wood in concentric rings around the original starting point.
If examined at the proper time with a hand lens, the small,
red, globular fruiting bodies of this sac fungus can be seen
clustered on the edges of the cankered area. All cankered limbs
should be removed and the larger cut surfaces be given a coat
of paint.
Fly Speck, Leptothyrlmn Ponii (Mont. & Fr.) Sacc. Plate
XI, d. The small black spots, similar to fly specks, produced
by this fungus are usually clustered on the fruit in numbers
from half a dozen to a hundred or more. The conditions favor-
able for sooty blotch also produce this fungus, so the two are
300 CONNECTICUT EXPERIMENT STATION REPORT, I903.
often found together. The former trouble, however, proves to
be the more serious as it is more abundant and evident. So far
the writer has not found the fly speck fungus in a fruiting
condition, though it is classified with the sac fungi. A similar
fungus was sent to the Station on peach twigs in a fruiting
condition, last year, so it is not unlikely that this fungus winters
on the apple twigs. •
Leaf Spots, Phyllosticta sps. Not unfrequently one finds
species of the Phyllosticta fungi on the round brown spots on
apple leaves and apparently the primary cause of these. As
stated before, most of these leaf spots are caused by the black
rot fungus. The fruiting stages of the two fungi are often
found in the same spot. At yet little is known of the life his-
tory of these Phyllosticta fungi, but they are possibly summer
stages of sac fungi.
Pink Mold, Cephalothecmm roseum Cda. During the fall
of 1902, this fungus, which commonly occurs only on decaying
vegetation, caused very serious loss to the apple growers of New
York state and to a less extent in this state. The trouble devel-,
oped after the apples were picked for storage. Its development
was the direct result of badly scabbed apples, and a wet fall,
since it was only through the scabby spots that the mold gained
entrance to the fruit. These spots became covered with a lux-
uriant white growth of mycelial threads, which on producing
the spores changed to a pinkish color. The mycelium also
penetrated the tissues and caused the rot of the apple. Cold
storage checked the trouble but did not prevent the rotting of
the apples when again brought into a warm atmosphere. The
prevention of this trouble requires a treatment that goes back
to the prevention of scab.
Powdery Mildew, PodosphcBra leucotricha (Ell. & Ev.)
Salm. This is usually a pest only in nurseries, though occa-
sionally found in orchards on sprouts at the base of the trees.
It forms a cobweb-like growth on the leaves and on the young
twigs a dirty whitish felt, within which are embedded the small
brownish spherical receptacles of the asco-spores. It thrives
best in nurseries where the blocks of trees are very closely
planted, and may be avoided by thinner planting and spraying
with potassium sulphide or Bordeaux mixture.
NOTES ON PARASITIC FUNGI. 3OI
RusTS^ Gym7io Sporangium macropus Lk., G. glohosum Farl.
Plate XI, c, Colortype 2. Two rusts, similar in appearance,
occur here on the apple leaves, the former apparently the more
abundantly. The apple stages {Rcestelia pirata and R. lacerata)
are the I or cluster cup stages of the mature forms which occur
as "Cedar apples" on cedar trees in late April to June. Infec-
tion of the apple leaves takes place in May or June, producing
bright orange-colored spots that begin to show prominently in
July. The fringed cluster cups [Plate XI, c] appear on the
under surface of these the latter part of July and August, and
their spores carry the fungus back to the young cedar twigs
for new infection. There is great difference in the susceptibility
of different varieties of apple to the attack of these fungi. One
often sees certain varieties of trees in the orchard and nursery
badly infected while others are free. Selection of varieties,
therefore, is one way of avoiding the trouble. Wealthy and
Fallowater, apparently, rust badly. Cedar trees in the vicinity
of the orchard should be cut down. Spraying, as yet, seems
to have given poor results. [Rep. 1891, p. 161 ; Bull. 142, p. 2.]
Scab, Venturia inceqiiaUs (Cke.) Aderh. Plate XII, a-b.
One of the fungi most widely discussed is the apple scab. This
is partly due to its general distribution and its injurious nature,
but also to the fact that it was one of the first whose control
was attempted by the use of fungicides. It occurs commonly
on the fruit and leaves ; very rarely on the twigs. On the
fruit it produces superficial olive-black "scabby" spots, that
often cause the young fruit to become one-sided and stunted.
Scabby fruit, also, is apt to wait in storage and become rotten
through infection with other fungi (see pink mold). On the
leaves the scab colonies, one-quarter to one-third of an inch in
diameter, are shown by a hand lens to consist of superficial
fertile threads radiating out from a common center. The only
specimens found on twigs [Plate XII, b] showed small pustules
not unlike those of the black rot fungus. Apple scab is the
parasitic summer stage {Fusicladium dendriticum) of a sac
fungus that develops as a saprophyte on the fallen leaves during
the fall and winter, maturing its spores in early spring in time
for infection of the unfolding leaves. Spraying experiments
have shown that this trouble can be controlled by Bordeaux
mixture. The first treatment is given on the unfolding leaves
3G2 CONNECTICUT EXPERIMENT STATION REPORT, I903.
before the blossoms open, the second just after the petals fall,
and the third, if necessary, follows two or three weeks later.
Sometimes a winter treatment with copper sulphate is given on
the dormant wood, but this is hardly necessary. [Rep. 1893, pp.
^2, 88; Bull. 142, p. 2.]
Sooty Blotch, f Phyllachora pomigena (Schw.) Sacc. Plate
XI, b. During the past two seasons this has been one of
our most serious apple pests. The fungus forms a prostrate
growth of matted threads, that in olive-black colonies more or
less cover the surface of the fruit. Because of its superficial
growth the fungus thrives best under moist conditions, such as
the past two seasons have afforded. It attracts most attention
on the lighter skin varieties, as the Greening, because of the
contrast in color. The injury to the fruit, at first, is chiefly
in its appearance, but this is sufficient to greatly affect the
market value. Later, ill effects are shown in the keeping quali-
ties, as badly spotted fruit wilts badly, because of the rupture
of the cuticle covering the apple, and not infrequently rotting,
from other fungi, develops. So far the writer has not found
the mycelium on these blotches producing spores, though apples
were kept out doors over winter for this purpose. The fungus,
however, probably belongs with the sac fungi. It occurs less
prominently on the pear. The treatment ordinarily given for
apple scab proves beneficial in keeping this trouble in check. To
be most effective, the third spraying should be given when the
fruit has attained considerable size. [Rep. 1897, p. 171 ; Bull.
142, p. 2.]
Baldwin Spot. This trouble shows first in the fall as small
sunken rotten spots on the Surface of the fruit and later as
isolated brown spots within the flesh, the tissue in these often
collapsing. When first studied it was thought that fungi or
bacteria might be responsible, but now it is generally considered
a physiological trouble, possibly resulting from too great loss
of water at these places. The trouble increases after storage,
especially in the development of the internal spots. Very similar
spots have been found in the interior of potatoes, which probably '
result from similar causes and conditions. During the past sea-
son Baldwin spot was more prevalent than usual, being common
in Baldwins especially. The poor condition of apples, induced
by the peculiar growing season, and by the September gale
NOTES ON PARASITIC FUNGI. 3O3
which shook most of the fruit from the trees, may possibly
explain its greater prevalence.
Fruit Scald. This is a more serious trouble with cold storage
apples than with those stored in the ordinary way. It shows as
large brownish scalded places at first on the skin, but eventually
penetrating deeper and is usually most prominent on fair skin
varieties. While the cold no doubt has much to do with
developing this trouble, it also seems certain that the condition
of the apples as they enter storage is a very important factor.
It is a trouble that is under investigation by our government
pomologists.
Spray Injury. Injury to the foliage and the fruit often fol-
lows spraying with Bordeaux mixture, especially when combined
with insecticides. Circular brown spots are produced on the
leaves very similar to those caused by the leaf spot fungi and
if the injury is sufficient many of these leaves are shed pre-
maturely. The injury to the fruit shows as russeting, and
may cause lop-sided growth. Carelessness in preparing the Bor-
deaux, failing to properly neutralize the copper sulphate with
fresh lime, is sometimes responsible for these injuries. In wet
seasons, injury sometimes results where proper precautions have
been taken. As a rule, the earliest sprayings on the undeveloped
leaves do not seem to cause injury so frequently as later spray-
ings on the fully matured leaves.
Winter Injury. Plates IX, a-b, X, b,. As stated in the
introduction, many apple trees were severely injured by the
sudden zero weather of December 9, 1902. This was due to
the sudden change following an open fall in which the trees
had not properl}^ matured for winter' conditions. The winter
of 1903-4 has also been a ver}^ severe one, but the trees were
in better shape for it. The injury in 1902 was shown in two
ways. First: In the nursery or very young orchard, especially
where the trees were cultivated late and thereby taken into
winter in an unripe condition, the injury was confined principally
to the wood, the bark and the cambium remaining uninjured.
This injury became evident only on cutting across the stem, when
the wood [Plate X, b] showed a darker color than normal.
When these trees were transplanted the following spring, the
unfavorable conditions of a dry May and a wet June finished
the career of many. When left in the nursery and severely
304 CONNECTICUT EXPERIMENT STATION REPORT, I9O3.
pruned back they made a more or less satisfactory growth accord-
ing to the severity of the injury. This new growth of wood
showed as a white ring in striking contrast to the injured dark
wood within. See Plate X. If the old wood was severely
injured, even if the new wood grew fairly well, there was fre-
quently developed an evident whitish fungous growth at the
pruned surfaces on the injured wood, showing that there was
trouble ahead from wood rot. Badly injured trees, too, were
very brittle and easily broken off. Second: In orchards, most
commonly on trees four to eight years old, the injury often
showed as dead areas in the bark, usually at the base of the tree
and more frequently on the northerly exposures. Sometimes
these sunken areas completely girdled the tree, thereby finishing
its career ; again they extended a foot or two up one side, being
separated by a fissure from the healthy bark. Trees injured
severely in this way put out an abundance of healthy foliage
early in the season and appeared in normal health until July,
when the leaves began to drop. Plate IX, a, shows a young
tree in Mr. Gold's orchard at West Cornwall, photographed
in July, 1902, that was losing its foliage because of a similar
injury to the base of the tree. These dead areas resemble
cankered spots, and the writer mistook, at first, the injury at
West Cornwall for a fungous trouble, since on some of the dead
areas the fruiting pustules of a fungus [Plate IX, b] were found.
Evidently these were developing as a later and saprophytic
growth. The healthy bark with its lenticels, which are some-
times mistaken for fungous growths, is shown in Plate IX, c.
Sun scald is also a winter injury of the bark due to warm
weather, starting into activity the tissues on southerly exposures
of the trunk, followed by a sudden freeze.
ASH, Fraxinus sps.
Leaf Speck, Piggotia Fraxini B. & C. This produces very
small black fruiting pustules on the under surface of the leaves
of white ash.
Rust, ^^cidimn Fraxini Schw. This rust forms its cluster
cups on the leaves and their petioles in July and August. Often
it produces considerable distortion of the petioles where these
spore cups are embedded. It was observed on the white ash,
F~. Americana.
NOTES ON PARASITIC FUNGI. 305
ASPARAGUS, Asparagus officinalis.
Anthracnose^ F'usarium sp. This trouble is sometimes asso-
ciated with the rust on asparagus stems. It causes light-
colored areas that become dotted with numerous pink pustules
of the spores. The tissue is killed at these places and so where
abundant the fungus may cause considerable injury.
Leopard Spot. Apparently this is the result of some fungus,
though it has not been found in a fruiting condition. It pro'-
duces reddish brown spots usually with a distinct border.
RusT_, Puccinia Asparagi DC. By far the most serious fun-
gous pest of asparagus, however, is the rust. This shows as
dark red or black pustules breaking through the skin on any
part of the plant. These small pustules are usually oval in
shape, though they may become more elongated, especially on
the larger branches. The reddish color indicates the formation
of the uredo- or summer spores, while the black color shows the
presence of the teleuto- or winter spores. These different spores
may even occur in the same pustules ; they are most abundant
from August to October. The cluster cup stage appears as
early as June, but does little damage and so far has not been
observed by the writer. During the past season the rust was
later than usual in appearing and consequently less destructive.
Some growers in Connecticut are now spraying against this
trouble, but the work to be effective must be done thoroughly
and repeatedly. Resin Bordeaux seems to be the best fungicide
for this purpose because of its sticking qualities. Spraying
should begin the latter part of July and be continued until the
middle of September. Sometimes the dead fields in the fall are
burned over to kill off at least some of the spores. According
to some growers the Palmetto is more exempt from rust than
most of the varieties. [Rep, 1896, p. 281 ; Bull. 142, p. 3.]
ASTER, Callistephus hortensis.
•Rust, Coleosporium Sonchi-arvensis (Pers.) Lev. This rust
has been found so far only sparingly on cultivated asters. In
nature it is very common on wild asters and goldenrods. The
bright orange uredo pustules appear in clusters on the under
surface of the leaves.
Stem Rot, Ftisarium sp? Some of our growers report as
306 CONNECTICUT EXPERIMENT STATION REPORT, I903.
serious a stem rot or decay at the base of asters. This is prob-
ably caused by a Fusarium fungus, though no special study was
made of this trouble, which evidently becomes established in
the soil.
Yellows. Apparently this is a physiological disease, which
may be similar to peach yellows. Affected plants are often
spindling with some yellowish or whitish foliage and usually
develop one-sided flowers imperfect in shape and color. Some
growers think that the trouble becomes worse on ground used
year after year.
AZALEA, Azalea sp.
Rust, Pucciniastrum Vacciniorum (Lk.) Diet. The uredo
stage of this rust was seen in a local nursery doing considerable
injury to certain cultivated azaleas, apparently native varieties.
The rust showed on the under surface of the leaves as very
small thickly crowded orange dots, while the upper surface was
somewhat discolored by the injury to the tissues.
BAEBEERY, Berberis sps.
Anthracnose, Gloeosporium Berberidis Cke. In midsum-
mer barberry leaves are often found showing at their tip or
margin dead areas which in time may involve the entire leaf.
These brown "tip burns" are separated from the healthy green
tissue by a distinct purplish border. The very small fruiting
pustules can sometimes be made out, on the underside near the
healthy tissue, by aid of a lens.
Rust, Puccinia graminis Pers. The cluster cup stage of the
common black stem rust of cereals occurs on both the wild and
cultivated barberry. This appears in May embedded in slightly
swollen clusters on the undersides of the leaves. See Oats.
BARLEY, Hordemn sps.
Powdery Mildew, Erysiphe graminis DC. The conidial
stage (Oidimn monilioides) of this mildew occurs on the leaves
in greyish moldy tufts, causing discoloration of the tissues.
Rusts, Puccinia graminis Pers., P. rubigo-vera (DC.) Wint.
These common rusts cause considerable damage to barley raised
for green fodder. See Oats.
Smuts, Ustilago nnda (Jens.) Kell. & Sw. Plate XIII, a.
NOTES ON PARASITIC FUNGI. 3O7
The loose smut is not uncommon in the spikelets of barley,
changing them into dusty olive-black spore masses. The
covered smut (U. Hordei (Pers.) Kell. & Sw.), which has a
firmer blacker spore mass, has been seen but once. These
troubles may be prevented by the modified hot water treatment
of the seed.
BEANS: STRING, Phaseohis vulgaris; LIMA, P. lunatus.
Anthracnose, Colletotrichum Lindennithianiiin (Sacc. &
Magn.) Bri. & Cav. Plate XIII, c. This is a common trouble
of beans. It occurs on both the pods and the leaves, producing
on the former evident subcircular spots with a distinct reddish
purple border. The bacterial trouble described later seems to
be more common on the leaves than this, and most of the spots
examined on bean leaves have been due to that. Anthracnose
often gets started through infested seed ; so only sound plump
seed should be used. Destroying infected seedlings and the
first diseased leaves should prove helpful in checking its appear-
ance. Spraying with Bordeaux should begin when the plants
are only a few inches high and be continued at intervals of two
or three weeks until the pods are maturing. Burning the rubbish
at the end of the season is recommended, since the trouble is
probably carried by this in the soil. [Bull. 142, p. 3.]
Blight,, Pseudomonas Phaseoli Smith. Plate XIII, d. This
is very common on the leaves of string beans, producing brown
dead areas at the tip or margin or large irregular spots within,
the leaf often turning yellowish all over and dying. Parts of
these diseased areas often have a pellucid or water appearance.
On the lima bean leaves, one often finds smaller reddish bordered
spots distinct from the above and similar in appearance to those
of anthracnose ; yet even these seem to be of bacterial origin,
probably started by insect punctures. See note by Sturgis in
Report 1898, p. 262. The treatment for blight is the same as
for anthracnose. [Bull. 142, p. 4.]
Downy Mildew, Phytophthora Phaseoli Thaxt. Plate
XIII, b, Colortype 12. This fungus was first described from
specimens found near New Haven by Professor Thaxter in
1889. It occurs only on the lima bean and has since been found
in a few other eastern states. It occurs most commonly on
the pods, covering them more or less completely with a con-
308 CONNECTICUT EXPERIMENT STATION REPORT, I903.
spicuous white felt of the myceHum and summer spore stage.
This distorts and often aborts the pods, rendering them unfit for
the market. Less commonly the fungus attacks the flowers
and young leaves and stems. It is most prevalent in moist
seasons and in the low wet places in the fields. Too close plant-
ing of the vines also induces its development. Just how the
fungus passes the winter still remains a mystery, as the winter
or oospores have never been found, though looked for carefully
by the writer and others. Probably the mycelium gains entrance
to some of the seeds and it is carried over this way. Wet, low
land should not be used and the plants should stand far
enough apart to admit plenty of sunshine. Spraying every
two or three weeks from the last of June until September
is helpful in controlling the trouble. The first sprayings may
be made with Bordeaux and the later with Amm. Sol. Cop.
Carbonate. The diseased pods should be gathered at each pick-
ing. [Reps. 1889, p. 167; 1890, p. 97; 1893, p. -jy; 1897,
p. 159; 1898, p. 236; Bull. 142, p. 4.]
Leaf Blotch, Isariopsis griseola Sacc. (Cercospora colum-
nar e E. & E. ) In one field this was found abundant, producing
angular brownish areas of varying size and giving the leaves
a sickly yellowish color. With a lens the fruiting stage can
be seen, as small black columns with greyish bushy heads, stand-
ing out on the under surface of the leaves. It was also found
on the old pods.
Leaf Spot, Phyllosticta phaseolina Sacc. This was seen
once. It produces large dark spots showing concentric
markings.
Mold, Fusariuni sp. If beans are left too long in the field
in the fall or if not properly matured when stored, this fungus
develops a vigorous growth of white mycelium over and in the
seeds.
Rust, Uromyces appendicnlafus (Pers.) Lk. Plate XIII, e.
This is very injurious to some varieties, including both dwarf
and pole forms of the string beans. The small, roundish, dusty,
reddish black pustules that usually thickly cover either surface
of the leaves contain the uredo- and teleuto-spores. These
occur occasionally on the pods. The rust is most common in
August and September. Avoid planting varieties that rust
badly, and burn the rubbish in the fall. [Bull. 142, p. 4.]
NOTES ON PARASITIC FUNGI. 309
BEET, Beta vulgaris.
Leaf Blight, Cercospora beticola Sacc. Plate XIV, a.
This is a very common trouble on beets and chard. The leaves
are more or less covered with roundish spots, one-sixteenth to
one-quarter inch in diameter, which have a greyish center and
a purplish border. Only summer spores are known, placing it
with the imperfect fungi.
Scab, Oospora scabies Thaxt. This causes scabby spots on
the roots similar to .those on potatoes. In an experiment,
Sturgis found that "beets, mangels, turnips and ruta-bagas are
susceptible to potato scab in a marked degree if planted on soil
infested with the fungus causing that disease. None of these
root crops, therefore, should occupy land which has recently
borne scabby potatoes." [Rep. 1896, p. 266.]
BLACKBEKRY, Riibiis villosus and vars.
Crown Gall, ? Dendrophagiis globosiis Toum. Reported on
this host but not seen by writer. See Raspberry.
Leaf Spot, Septoria Riibi Westd. Plate XIV, b. This is a
common trouble on the foliage, producing small, circular spots
that eventually have a whitish center with a purple border. The
fruiting pustules when present show as minute black dots sunken
in the white area. It is caused by one of the imperfect fungi
and occurs also on the raspberry and dewberry. It is ques-
tionable just how much damage this causes when fairly abun-
dant, but if it proves serious, early spraying with Bordeaux
would probably pay. [Bull. 142, p. 4.]
Orange Rust, Gymnoconia interstitialis (Schl.) Lagerh.
Plate XIV, c, Colortype 9. This forms orange colored dusty
outbreaks thickly covering the under surface of the leaves from
May to July. At first these are covered by the epidermis, upon
the rupture of which the spores are gradually scattered. Orange
rust {Cceoma nitens) is the I stage of the mature form III, or
teleutal, which occurs later in very inconspicuous pustules on
the same plants. The mycelium is perennial in the underground
parts of the host, so that shoots year after year from these will
be rusted. The best remedy is to dig up and destroy the infected
plants as soon as discovered ; it is especially desirable to remove
them early in the spring before the spore pustules break open.
Certain varieties seem more subject to this trouble than are
3IO CONNECTICUT EXPERIMENT STATION REPORT, 1903-
others, and it also occurs on the raspberry and dewberry and
on wild plants of all of these. It is well to see that none of
the latter flourish in the vicinity of the cultivated plants. [Rep.
1889, p. 172; Bull. 142, p. 4.]
BLUE GRASS, Poa pratensis.
Powdery Mildew, Erysiphe graminis DC. The conidial
stage of this mildew often occurs on uncut grass in fence rows,
etc. It forms a white powdery coating on portions of the
leaves.
BOX ELDER, Negundo aceroides.
Leaf Spot, Phyllosticta minima (B. & C.) Ell. See Maple.
BROME GRASS, Bromus inermis.
Ergot, Claviceps pvirpurea Tul. Collected once on this and
several times on other species of Bromus; sclerotia smaller than
on rye, q. v.
BROOM CORN, Sorghum vulgare var.
Grain Smut, Sphacelotheca Sorghi (Lk.) Clint. Collected
in Experiment Station grounds. See Sorghum.
BTJCKWHEAT, Fagopyrum esculenhim.
Leaf Blight, Ramularia rufomaculans Pk. Plate XIV, d.
Occasionally this becomes abundant and injurious in buckwheat
fields, but usually it is found only sparingly. Its fruiting stage
forms whitish, mealy growths scattered in patches over the
under surface of the leaves. This summer spore stage is the
only one known. [Rep. 1890, p. 98.]
Leaf Spot, Ascochyta sp. Another trouble occasionally
found on the leaves produces circular, reddish brown spots.
These and the fungus causing them are very similar, if not the
same as the leaf spot of Rhubarb.
CABBAGE, Brassica oleracea.
Club Root, Plasmodiophora BrassiccE Wor. Plate XV, a.
This forms gall-like enlargements on the roots. These are mor-
bid growth of plant tissue, the cells of which are filled with the
spores, etc., of the slime mold that produces the trouble.
NOTES ON PARASITIC FUNGI. 3 II
Eventually the infected tissues rot, through the action of bac-
teria, and liberate these germs in the soil. Badly infected plants
have little root hold in the soil and so are cut off from gathering
sufficient plant food. They become spindling and head out
poorly, if at all. The trouble becomes established in the soil
when garbage is dumped on it or the refuse from the diseased
crop is left in the fields. For this reason infected land is not
adapted for raising cabbage or the similar cruciferous plants,
cauliflower, turnip, etc. The disease even spreads to cruciferous
weeds in the fields, as shepherd purse, and pepper grass.
Rotation with different crops should be followed. The young
plants should never be grown in infected soil. If an- infected
field is ever used, a fall coating with lime sown broadcast at
the rate of eighty bushels per acre, is said to be helpful in keep-
ing the trouble in check. [Bull. 142, p. 5.]
Leaf Molds^ Alternaria Brassicce (Berk.) Sacc, A. BrassiccB
var. macrospora Sacc. These cause subcircular, blackish spots
of varying size on the leaves. The variety seems to be the
more common and has very large spores as seen under the
microscope. The same fungus occurs on mustard and radish.
Occasionally the trouble becomes rather prominent.
Soft Rot^ Bacterial. Often the leaves of the heads are more
or less destroyed by a wet brown rot, which may become serious.
CAENATION, Dianthus Caryophyllus.
Fairy Ring, Heterosporium eckinulatum (Berk.) Cke. This
forms on the leaves greyish spots, about a quarter of an inch
in diameter, having a distinct purplish border. The fruiting
stage shown under a lens is an olive black, upright growth of
threads. When occurring on the calyx, it often causes this to
crack open, which is very objectionable to the growers. Usually
the trouble occurs seriously only in neglected houses. [Bull.
142, p. 5-1
Grey Mold, Botrytis vulgaris. vSometimes occurs on the
blossoms. See Lettuce.
Leaf Spot, Septoria Dianthi Desm. This often occurs with
the preceding and the two look very similar. The leaf spot can
usually be distinguished by the small black dots, or fruiting
receptacles, that are embedded in the center of the spots. Only
21
312 CONNECTICUT EXPERIMENT STATION REPORT, I903.
good plants should be selected for cuttings and all dead leaves
removed as they appear. Care is needed in watering. It is
easier to keep out these troubles by giving the plants the very
best treatment than it is to control them after they are thoroughly
started.
Rust, Uromyces caryophyllinus (Schrank.) Schrt. Plate
XV, b. Rust is the most troublesome of the fungous pests of
carnation. It breaks out in reddish brown dusty pustules
on the leaves and stems. Both uredo- and teleuto-spores occur,
but the former are more common. There is considerable differ-
ence in the susceptibility to rust with the various varieties.
Eldorado, Daybreak, Jubilee, and others are said to rust badly,
while Prosperity, Portia, etc., are more exempt. The conditions
of different greenhouses and the care given by the growers also
make differences in the amount of rust. Plants crowded too
closely or watered too freely on the foliage and at improper
times rust the worst. Many growers remove the rusted leaves,
if not too numerous. No doubt very careful attention to this
treatment when the plants are first started and little rust is
found, would always repay. Spraying experiments have been
carried on to some extent. Bordeaux mixture is objectionable
to the grower on account of the sediment. Potassium sulphide
to be of value should be applied in season, and repeatedly.
[Bull. 142, p. 5.]
Stem Rot_, Rkisoctonia sp. This sterile fungus was found in
connection with the rot in one greenhouse. As the fungus lives
in the soil, it is desirable to keep it from becoming established,
since it will attack other plants as well.
Wilt, Fusarium sp. In the Report for 1897, pp. 175-81, Dr.
Sturgis reports this troublesome to carnations grown in the
Experiment Station greenhouse. Perhaps both this and the
preceding fungus are responsible for the common stem rot
trouble of growers. The soil, if necessary, can be sterilized
with steam to rid it of these fungi.
CARROT, Daiicus Carota.
Blight, Bacterial. While visiting a seed farm in the vicinity
of Milford in 1902, there was observed a rather serious trouble
of this host due to bacteria. The infected plants showed a wet
rot, confined chiefly to the outer layers of the stem. These
NOTES ON PARASITIC FUNGI. 313
had a greenish black color, were watery and easily mashed out
of place with handling. To a less extent the leaves showed
blackened spots and the inflorescence was somewhat infected.
An examination of these injured parts showed plenty of bacteria,
which were, no doubt, the cause of the trouble, though no experi-
mental or cultural work was undertaken with them. So far
the writer has seen no description by others of this trouble on
the carrot.
CATALPA, Catalpa sps.
Powdery Mildew, Microsphcera elevata Burr. In nurseries
especially, but occasionally on the shade trees of lawns, this
fungus is found coating the leaves on their upper surface with
a more or less conspicuous cobweb-like growth. Imbedded in
the dirty white mycelium occur the small black receptacles con-
taining the winter or asco-spores. In the nurseries the trouble
ought to be easily controlled by spraying with potassium
sulphide.
CEDAR, Jimiperus Virginiana.
Cedar Apples, Gynmosporangium macropus Lk., G. gloho-
sitm Farl. Colortype 2. The teleutal stage of apple rusts occurs
on this host. The "cedar apples"- are reddish gall-like bodies
that in the moist weather of spring send out elongated jelly-
like horns all over their surface. These contain spores that
germinate in position and produce smaller thin-walled spores,
that, on the drying of the horns, are carried by the wind to the
apple leaves, where their infection produces the cluster cup
stage. The two species on the cedar are . distinguished by the
longer, more tapering horns of G. macropus, which is the more
common species. See Apple.
CELERY, Apmm graz'eolens.
Leaf Blight, Cercospora Apii Fr. The so-called "rust" of
growers shows as reddish brown irregular spots on the leaves.
If badly infected, these turn yellowish and have a sickly appear-
ance. The fungus can usually be seen by a hand lens as a
not very evident upright surface growth. This is one of the
most serious troubles of the celery grower. At bleaching time
rusty spots of this or the next fungus may appear on the stalks.
314 CONNECTICUT EXPERIMENT STATION REPORT, I903.
Where the trouble is Hkely to prove serious, spraying should
begin soon after transplanting. Bordeaux is used for the first
and usually Amm. Sol. Cop. Carbonate for the later sprayings.
Applications should be made about every two weeks up to the
time of banking. Sturgis found that dusting sulphur over the
plants was also an effective treatment. [Reps. 1892, p. 44;
1893, pp. 81, 103 ; 1897. P- 167; Bull. 142, p. 5.]
Leaf Spot, Septoria Petroselini var. Apii Br. & Cav. This
is a trouble very similar to the preceding and the preventive
treatment is the sam.e. The two may occur together; but the
leaf spot is usually distinguished by the small black dots, or
fruiting receptacles, in the rusty spots.
CHAEB, Beta vulgaris var.
Leaf Blight, Cercospora heticola Sacc. See Beet.
CHEERY, Prunus sps.
Black Knot, Ploivrightia morbosa (Schw.) Sacc. Occurs
injuriously on cultivated species and also on the wild species,
Prunus serotina and P. V.irginiana. See Plum.
Brown Rot, Sclerotinia fructigena (Pers.) Schrt. Occurs '
on both Prumts Cerasus and P. Avium. ~ See Peach.
Leaf Curl, Exoascus Cerasi (Fckl.) Sad. The leaves
become badly discolored and somewhat deformed when attacked
by this fungus. Those worst infected usually drop off. The
trouble, apparently, is not common, but was collected a few times
in 1900 by Sturgis.
Leaf Spot, Cylindrosporium Padi Karst. Colortype 11.
The crowded, small, purplish spots produced on the upper sur-
face of the leaves by this fungus are shown very well by the
colortype frontispiece. On the under surface the spores fre-
quently show as small, pinkish, agglutinated masses. Badly
infected leaves turn yellowish and drop off. The trouble is one
of the most common and serious occurring on the cherry; it
also occurs on the wild black cherry, P. serotina, and occasionally
on cultivated plums. Spraying with Bordeaux mixture, start-
ing early in May, has successfully prevented the disease else-
where. [Rep. 1890, p. 102; 1895, p. 188; Bull. 142, p. 6.]
Powdery Mildew, Podosphcera oxyacanthce (DC) DeBy.
Plate XV, c. This is most injurious to young trees. The
NOTES ON PARASITIC FUNGI. 31$
under surface of the leaves, and to some extent the upper,
becomes covered with the white myceHum of the fungus. In
the fall, the winter spore stage is conspicuous, through the
numerous small black perithecia (Plate XV, c) scattered among
the fungous threads. The trouble can readily be controlled in
the nurseries where it is injurious, by spraying either with
Bordeaux mixture or potassium sulphide, if taken in time.
[Bull. 142, p. 6.]
CHESTNUT, Castanea sativa.
Anthracnose^ Marsonia ochroleuca (B. & C.)' Humph.
Colortype 5. This forms conspicuous spots with brownish cen-
ters and purplish borders, on the leaves. It is most injurious
to young nursery trees, but probably could be prevented by
proper spraying.
CHRYSANTHEMUM, Chrysanthemum Sinense.
Anthracnose, Cylindrosporium Chrysanthemi Ell. & Dearn.
Greenhouse chrysanthemums sometimes suffer from this trouble.
It produces large, brownish or blackish spots or blotches, some-
times covering the entire leaf.
Powdery Mildew, Oidium Chrysanthemi Rabh. This is a
very common trouble in greenhouses, the leaves becoming cov-
ered with a mealy white growth. Apparently it is only the
conidial stage of one of the Erysipheas, but the winter stage is
never produced. Ada Prass, Colonel Appleton, Omega, Merula
and Julinda apparently mildew worse than Major Bonnaffon,
Glory of Pacific, George W. Childs, or Ivory. The treatment
for this should be the same as for mildew of rose, q. v.
Rust, Puccinia Chrysanthemi Roze. Plate XV, d. Only the
uredo-stage of this rust seems to occur in this country on the
chrysanthemum. This is a recent trouble, though one of the
worst of this host. The dusty outbreaks of the reddish brown
spores are about the size of a pin-head. These occur more or
less abundantly on the under surface of the leaves. Attention
should be given to the removal of infected leaves as soon as
seen. Queen, Black Hawk, Ada Prass, Timothy Eaton, seem
to rust worse than Miss Pullman, Major Bonnaffon, V. H.
Hallock.
3l6 CONNECTICUT EXPERIMENT STATION REPORT, I9O3.
CLEMATIS, Clematis Virginiana.
Leaf Spot, Cylindrosporium Clematidis Ell. & Ev.
CLOVER, RED, Trifolium pratense.
Black Dot, Phyllachora Trifolii (Pers.) Fckl. Colortype 6.
The under surfaces of the leaves are usually rather thickly cov-
ered by the small black pustules of this fungus. It also occurs
on white clover (T. repens) and crimson clover (T. incarnatum) .
It is not uncommon in clover fields.
Black Mold, Macrosporium sarcinceforme Cav. This is also
troublesofne in some clover fields. It produces on the leaves
reddish circular spots that often show faint concentric rings of
development. The fruiting stage is very inconspicuous on these
spots.
Leaf Spot, Pseud opeziza Trifolii (Bernh.) Fckl. So far this
fungus has not been found very common on the leaves, where it
produces irregular reddish brown spots, in the center of which
may sometimes be seen the small fruiting disc.
Rust, Uromyces Trifolii (A. & S.) Wint. Plate XVI, a.
the secidial or cluster cup stage was collected by Thaxter in
June on white clover. Apparently this is not so common as the
uredo- and teleuto-stages, which are found in July and August
very commonly on red and white clover. They appear chiefly
on the under surface of the leaves as reddish, dusty pustules.
Perhaps this is the most abundant and injurious of these clover
fungi ; it is not uncommon to find two or more of them on the
same leaves. [Reps. 1889, p. 174; 1890, p. 98.]
COLUMBINE, Aquilegia sp.
Leaf Spot, Ascochyta sp. The large purplish blotches or
diseased areas often seen on the leaves of cultivated columbines
seem to be caused by a species of Ascochyta, one of the imperfect
fungi.
Powdery Mildew, Erysiphe Polygoni DC. Occasionally
this is found forming a whitish mycelial growth, with plenty
of the perithecia showing as small black specks, scattered over
the surface of the leaves.
NOTES ON PARASITIC FUNGI. 31/
CORN, Zea Mays.
Blight, Bacillus Zea: Burr. This usually occurs on the
inner surface of the leaf sheaths, where it produces very evident
dark purplish discoloration showing slightly through the sheath.
Apparentl)^ it is not a serious trouble in Connecticut.
Leaf Blight, Helminthospormm turcicum Pass. {H. incon-
spicuum Ell. & Ev.). Colortype 13. Last year this proved a
very serious trouble to corn, many fields looking in August or
September as if struck by an early frost. The very unfavorable
season for maturing the corn was largely responsible for this
unusual attack. Elongated areas or even entire leaves were
killed, turning a brownish color and showing the fungus as a
very inconspicuous surface growth. Conspicuous growths of
other saprophytic molds, however, often appeared on these dead
areas. Sometimes the dead spots were small, but usually,
because of the venation, they developed into elongated areas.
Not all fields were equally affected and it was difficult to always
explain this. Possibly the maturity of the plants, or the charac-
ter of the seed from which they came, was a partial explanation.
Thaxter noted this as a serious trouble in Connecticut in 1889.
[Rep. 1889, p. 171.]
Rust, Puccinia Sorghi Schw. Apparently this possesses no
cluster cup stage. Both the uredo- and teleuto-spores develop
as reddish, dusty outbreaks on either surface of the leaves,
and can usually be distinguished by their color. While not an
uncommon fvmgus in the corn fields, it does not often prove to
be ver}^ serious.
Smut, Ustilago Zece (Beckm.) Ung. Plate ' XVI, b. The
conspicuous dusty smut balls of this fungus are familiar to every
one. They break out on any part of the host and vary greatly
in size and shape according to their situation. These smutty
masses are composed entirely of spores. The trouble is most
serious in sweet corn. Fresh manure applied to the land is
likely to increase the amount of smut in corn, since the spores
germinate in this and give rise, yeast-fashion, to numerous
secondary germs that have the power of infecting the corn.
This is practically the only cereal smut that can not be pre-
vented by seed treatment, as infection takes place through any
very young tissue. Some gather the smut balls to keep the
trouble from spreading, but it is questionable just how much
3l8 CONNECTICUT EXPERIMENT STATION REPORT^ I903.
good this does. This smut is not poisonous to stock, as is sup-
posed by some. [Rep. 1889, p. 171 ; Bull. 142, p. 6.]
COSMOS, Cosmos bipinnatus.
Leaf Spot, Septoria sp. Occasionally brown circular spots
are produced more or less abundantly in the leaves by a Septoria
fungus, whose fruiting bodies show as the usual little black
dots in the tissues.
COSMOS, Cosmus bipinnatus.
Stem Spot, Phlyctcea sp. Halsted, of New Jersey, gives this
as the cause of the large purplish blotches that appear on the
stems, especially at the lower nodes. It may eventually produce
a more or less serious rot of the stems.
CRAB APPLE (Beditel's), Pirus lonensis var.
Rust, Gymnosporangium macropus Lk. This occurs in its
aecidial stage, I, on the branches, as well as on the leaves, but
it does not seem to carry over the winter in the branches, as
an examination last spring of those infected the year before
failed to show any signs of a new development of the fungus.
See Apple.
CEOWEOOT, Ranunculus sp.
Powdery Mildew, Erysiphe Polygoni DC. Only the coni-
dial stage was found forming a mealy whitish growth over the
leaves.
CUCUMBER, Cucumis sativus.
Anthracnose, CoUetotrichtim Lagenarium (Pass.) Ell. &
Hals. See Watermelon.
Downy Mildew^, Plasmopara Cubensis (B. & C.) Humph.
This fungus does not produce so conspicuous spots on the leaves
of this host as it does on the musk melon; neither is the injury
so severe. The fruiting stage, however, shows more con-
spicuously and with a lens the scattered growth of upright
fertile threads bearing the large dark purple spores is easily
made out. Spraying gives beneficial results with this host.
Bordeaux should be used as soon as the vines begin to run
NOTES ON PARASITIC FUNGI. 319
and the treatments should be given often enough to keep the
foHage well covered with the sediment. The cucumbers may
be picked before each of the later sprayings, otherwise no
attention need be given to keep the spray off the fruit. See
Musk Melon. [Rep. 1890, p. 97.]
Powdery Mildew^ Erysiphe dehor acearum DC. Conidial
stage only occurs ; on the leaves.
ScAB^ Cladosporium cucumerinum Ell. & Arth. On leaves
and fruit. See Musk Melon.
WiLT^ Bacillus tracheiphilus Sm. See Squash.
CUREANT, Ribes ruhrum.
Anthracnose, Glozosporium Ribis (Lib.) Mont & Desm.
This is the most serious trouble of the currant. It causes
numerous purplish or reddish brown spots, about the size of a pin
head, on the upper surface of the leaves. Where abundant, the
intervening tissue is also killed and the leaf sheds prematurely.
On the under surface of these spots the spores show in small
pinkish globules. The trouble is often so serious that the bushes
are completely defoliated by August, thus cutting short their
season of usefulness. Spraying experiments, elsewhere, have
controlled this disease. The first treatment is given before the
leaves appear; the second as they are unfolding; others follow
at intervals of about two weeks until the fruit begins to turn.
[Bull. 142, p. 7.]
Leaf Spot, f Septoria Ribis Desm. This forms larger and
fewer spots than the last and the spores ooze out on the upper
surface. Apparently it is not common. The spots and spores
are not quite like those this fungus produces on the goose-
berry, q. V.
Red Knot, Nectria Ribis (Tode) Rab. Plate XVI, c. This
was found on currants badly infested with the San Jose scale,
which was chiefly responsible for the poor condition of the
bushes. It is a question whether the fungus does not occur
more commonly as a saprophyte than a parasite. It can be
told by the bright red fruiting bodies that break out in roundish
clusters on the stems. These are often accompanied by a coni-
dial stage {Tuber cularia vulgaris), which forms small roundish
pink cushions producing the summer spores. It will do no harm
t6 cut out all diseased branches.
320 CONNECTICUT EXPERIMENT STATION REPORT, I903.
DAHLIA, Dahlia variahilis.
Powdery Mildew, Erysiphe cichoracearum DC. Conidial
stage only formed.
DANDELION, Taraxacum officinale.
Powdery Mildew, Sphaerotheca Castagnei Lev. Found
sometimes on plants raised for greens.
DEWBERRY, Rubus Canadensis.
Leaf Spot, Septoria Riihi Westd. See Blackberry.
Orange Rust, Gymnoconia inter stitialis (Schl.) Lagerh.
See Blackberry.
DOGWOOD, Cornus sps.
Leaf Spot, Septoria cornicola Desm. This fungus produces
numerous brownish or purplish circular spots, usually less than
one-quarter of an inch in diameter, on the leaves. It was found
doing considerable injury to both Cornus sanguinea and C.
paniculata in nursery rows.
EGG PLANT, Solanum Melongena.
Fruit Mold, Botrytis sp. This is often responsible for the
rotting of the fruit. Its spore stage shows as a dense greyish
moldy growth covering the rotten area.
Fruit Rot and Leaf Spot, Phyllosticta hortorum Speg.
This was a serious trouble last year of t.gg plants, especially
on the fruit. It causes round brownish spots on the leaves
and the fruit gradually rots a reddish brown color, the spore
pustules showing as black dots. The spores produced in the
leaves are often septate and possibly larger than those on the
fruit. A Phlyctcena spore stage also often occurs in the same
pustules on the fruit with the Phyllosticta. This makes the
systematic position of the fungus uncertain, though Halsted
determines it as given above. The rotten fruit should be picked
and destroyed.
Leaf Mold, Alternaria Solani (E. & M.) J. & G. This
forms spots on the leaves very similar to the above fungus. See
Potato.
NOTES ON PARASITIC FUNGI. 321
Wilt. Last year the egg plants were often attacked by a
fungus that caused wilting, yellowing and eventually the death
of the leaves, especially the lower ones. This spemed to be the
result of a Fusarium that invaded the fibro-vascular bundles of
the stern and, by clogging the vessels, cut off the water supply
of these leaves.
ELM, Ulmus Americana.
-Leaf Spot^ Gnomonia ulmea (Schw.) Thm. Elm leaves are
very commonly attacked by this fungus, its fruiting stage show-
ing on the upper surface as small black pimples, often somewhat
clustered in circles. The spores mature in the old dead leaves
the following spring.
White Fungus, Sporotrichiim glohuliferum Speg. Plate
XVI, d. This is the fungus that was used some years
ago by the Kansas and Illinois Experiment Stations in experi-
ments to infect chinch bugs generally in the fields. In the
summer and fall of 1902, it was found in Connecticut on the
elm-leaf beetles, and as the next year the beetles were greatly
reduced in numbers it no doubt had considerable influence in
checking their ravages. The remains of the larvae were fre-
quently found under the loose bark of the trees, embedded in a
luxuriant white growth of the fungus (see Plate) . Under a hand
lens this shows the spores crowded into the numerous minute
spore balls so characteristic of the fungus.
ENDIVE, Cichorium Endivia.
Leaf Spot. A serious leaf spot trouble, apparently produced
by a fungus but not in a fruiting condition, was observed in
1902 in the vicinit}^ of New Haven. The leaves were so abun-
dantly covered with the circular brown spots as to render them
useless for the market.
Rust, Puccinia Endivice Pass. Apparently this rust has not
been reported before in this country, though it is a common
parasite of endive in Italy. It was probably introduced in New
Haven from that country, for the only place it was found was
in a large endive field owned by an Italian market gardener.
As endive should have perfect leaves for bleaching, the abundant
dusty pustules produced by the rust spoiled many plants or at
least rendered them second class. Only the uredo-spores were
found, even late in the fall.
322 CONNECTICUT EXPERIMENT STATION REPORT, I903.
GERANIUM, Pelargonium sp.
Grey Mold, Botrytis vulgaris Fr. This common mold occurs
in leaky or too moist greenhouses. Water dropping on the
plants from the roof often gives the fungus its chance for infec-
tion. Brown dead spots are produced on the leaves and under
moist conditions these develop the grey, moldy growth of the
fruiting stage.
Leaf Spot, Ascochyta sp. Produces large circular or irregu-
lar spots on the leaves ; not very common.
Stem and Leaf Rot, Bacterial. Complaint is sometimes
made of geraniums rotting off at their base or the leaves decay-
ing or spotting. The trouble seems to be caused by bacteria
and no doubt is often induced by too moist conditions. Affected
parts or badly diseased plants should be destroyed.
GOLDEN GLOW, Rudheckia laciniata.
Powdery Mildew, Erysiphe cichoracearum DC. Common,
but not very injurious, and occurring only in the conidial stage.
Stem Rot. The writer's attention has been called to a stem
rot trouble of golden glow that has appeared year after year
in the same bunch. Each year the rot attacks some of the stems
at their base, finally killing them by rotting the tissues and
choking up the water ducts. The trouble is carried over in
the soil by small black sclerotia, or compacted tubers of fungous
cells, that are formed on the rotting stems. The trouble is
probably caused by a Botrytis fungus.
GOOSEBERRY, Rihes sps.
Anthracnose, Glososporium Ribis (Lib.) Mont. & Desm.
Occurs occasionally on this host. See Currant.
Leaf Spot, Septoria Ribis Desm. Brownish or purplish
spots, often having a whitish center, are formed on the leaves.
The fruiting bodies, as minute black dots, may sometimes be seen
in these. Apparently this is not a common trouble.
Powdery Mildew, Sphcerotheca mors-uvce (Schw.) B. & C.
While this has never been collected by the Station botanists, it
has occurred in the state, as shown by reference to it in one of
the old Reports of the Agricultural Society, where it was named
as a serious trouble varying in different seasons. It forms a
NOTES ON PARASITIC FUNGI. 323
dirty white felt of mycelium on the young branches and leaves
and often on the fruit. Imbedded in this are the small reddish
black perithecia, containing the asco- or winter spores. Spray-
ing with potassium sulphide, beginning as soon as the buds
burst and repeating every two weeks until the end of June, is
said to hold this trouble in check.
GrRAPE, FiVw sps.
Anthracnose^ Sphaceloma ampelinum DeBy. The bird's
eye rot occurs on the leaves, stems and fruit. On the latter it
forms circular rotten spots with distinct, bright colored borders,
hence the common name. This generally yields to treatment by
spraying more readily than the next trouble. Diseased wood
should be removed. [Reps. 1889, p. 174; 1890, p. 102; 1893,
p. 98.]
Black Rot, Guignardia Bidwellii (Ell.) Viala & Rav. Plate
XVII, a. This is the most common and injurious trouble of
the grape. On the leaves it produces conspicuous, circular, red-
dish brown spots. In the small black dots imbedded in these
are produced one of the summer spore stages ( Phyllosticta Lab-
rusccB Thm.) of the fungus. This stage also occurs on the
leaves of the Virginia creeper and the Boston ivy, which are
related plants. The grapes, on rotting, first have a brown color,
but eventually dry up into wrinkled black mummies that adhere
for some time to the vine. In these, a summer spore stage,
similar to that on the leaves, is first produced, but other stages
are also formed, the asco-spore form appearing the next spring.
Black rot is a very difficult trouble to control, especially in wet
seasons, but persistent spraying year after year reduces the
trouble to a minimum. Spraying should begin before the blos-
soming period, about the last of May; the second applica-
tion follows after the plants blossom, and others at intervals of
ten to fourteen days. Bordeaux is used until the middle of
July, and then Amm. Sol. Cop. Carbonate or Soda Bordeaux
until the middle of August. The treatment should be thorough
for a couple of years until the disease is under control, when
the number of sprayings can be reduced from six or seven to
three. [Reps. 1889, p. 174; 1890, p. 100; 1893, p. 96; Bull.
142, p. 8.]
324 CONNECTICUT EXPERIMENT STATION REPORT, I903.
Downy Mildew, Plasmopara viticola (B. & C.) Berl. & De
Toni. Plate XVII, b. This fungus occurs on grapes grown
under glass, in the vineyards, and even more commonly on wild
species. The thick, white felt that is produced on the under
surface of the leaves, occasionally on the stems and fruit, bears
the thin-walled summer spores ; the thick-walled winter spores
are rarely formed within the tissues. The treatment given for
black rot should prevent this trouble also. When the vines are
treated for this alone, perhaps the sprayings need not be so
numerous. For grapes grown under glass, Sturgis found the
fumes of sulphur safer tO' use. [Rep. 1893, pp. yy, 97; Bull.
142, p. 8.-]
Grey Mold, Botrytis sp. Ripe fruit of greenhouse grapes
frequently rots by reason of a common Botrytis mold. . Atten-
tion should be paid to the moisture conditions in these houses.
Spraying tihe bunches with potassium sulphide or heating sul-
phur, probably would prove helpful. The rotting grapes should
be removed as soon as they appear.
Powdery Mildew, Uncinula necator (Schw.) Burr. This
mildew forms a cobweb-like growth on the upper surface of the
leaves or occasionally destroys the fruit. In the fall the peri-
thecia are easily seen as very minute reddish or black balls
scattered over the surface of the infected leaves. The treatment
for black rot should also prevent this. Where this alone is
troublesome, the later sprayings may be made with potassium
sulphide, if desired. Probably a very late spraying in the fall
would prove useful in checking the trouble the next year. The
Virginia creeper is also a host for the fungus. [Rep. 1895,
p. 185 ; Bull. 142, p. 8.]
Winter Injury. A very curious trouble was seen the past
summer on grapes grown under glass in New Haven. Appar-
ently it was a result of the sudden freeze of December 9, 1902,
since the greenhouse, contrary to the usual custom, was not
heated that winter and the injury was greatest on the west
or coldest side of the house. The trouble first showed during
the summer in morbid, gall-like growths of plant tissue, that
were formed usually at or toward the base of the vines. These
excrescences were more irregular and not so' dark colored as
black rot. By early winter this morbid tissue was dead and
somewhat pulverized by insect larvae. A similar trouble has
NOTES ON PARASITIC FUNGI. 325
been figured in one of the New York Experiment Station's
bulletins on grapes grown outdoors ; and has also been described
in Europe. It has usually been ascribed to cold weather. As
the wood on some of the vines described here also showed winter
cracks, this is probably the explanation of the trouble.
GrROTJND CHEEEY, Phy sails puhescens.
White Smut, Entyloma Physalidis (Kalchb. & Cke.) Wint.
The spores of the white smuts are permanently embedded in
the tissues, and of light color, so they do not have the
black, dusty appearance of the ordinary smuts. This smut of
the strawberry tomato, or ground cherry, forms whitish or
reddish angular spots on the leaves and is sometimes so abun-
dant as to cause serious injury to the foliage. The character
of the host, however, makes it of little economic importance.
HAWTHOEN, Cratcegns sps.
Leaf Spot, Entomosporium ThiimenU (Cke.) Sacc. This
produces small angular reddish or purplish brown spots on the
leaves of the English hawthorn, Crat<zgus oxyacantha, which
is sometimes grown in yards.
Rusts, Gymnosporangium macropus Lk., G. clavipes C. & P.
^cidial stages occur on leaves of cultivated redhaws.
HAZEL, Corylus sp.
Black Knot, Cryptosporella anomala (Pk.) Sacc. Plate
XVII, c. This fungus sometimes becomes very injurious to
the ornamental cut leaf hazel. In one nursery it proved so
destructive that the owner intended giving up growing this
variety.' The black knot infects the branches, breaking out
between the bark as oval bodies about one-quarter of an inch
in length, in the surface of which are embedded the fruiting
pustules.
HICKORY, Carya alba.
Anthracnose, Gloeosporium Caryce Ell. & Dearn. This
forms dark purple blotches on the leaves.
326 CONNECTICUT EXPERIMENT STATION REPORT, I903.
HOLLYHOCK, Althasa rosea.
Leaf Blight_, Cercospora althmna Sacc. The numerous,
small, angular spots produced on the leaves by this fungus are
reddish brown, often with a lighter center.
Leaf Spot, Ascochyta parasitica Fautr. This sometimes
occurs on spots associated with a rust pustule.
Rust, Puccinia Malvacearum Mont. Plate XVII, d. Rust
is the most common trouble of hollyhocks and the one most
frequently sent to the Station for determination. The fungus
shows as roundish cushions, of a light or dark red color, on
both leaves and stem. Only teleuto-spores are known and these
germinate in position so that the pustules are often covered with
a whitish growth due to this germination. Some think the
trouble is partially controlled by spraying, but this to prove
of benefit should begin before the appearance of the rust pus-
tules. Possibly the trouble might be checked the next year, if
in the fall the plants were all cut off below the ground and all
of the rubbish destroyed by fire. [Rep. 1895, p. 188.]
HONEYSUCKLE, Lonicera sp.
Powdery Mildew, Microsphcera Lonicer^ (DC.) Wint.
Observed occasionally on Tartarian honeysuckles in old gardens.
HORSECHESTNUT, ^scidus Hippocastanum.
Leaf Spot, Phyllosticta Pavics Desm. A very serious leaf
trouble of the cultivated European horsechestnut is caused by
this fungus. The large dark red blotches often reach from the
margin to the midrib and resemble sunburn. On the upper
surface the minute black dots of the fruiting stage are often
visible,
HORSEEADISH, Cochlearia Armoracia.
Leaf Blight, Ramularia ArmoracicB Fckl. This is the
fungus ordinarily reported on horseradish, but it does not seem
so common here as the next two. The spots are smaller and
paler and the leaf tissue often falls out, giving a shothole effect.
Leaf Mold, Macrosporitim herculeiim E. & M. It is ques-
tionable if this is distinct from M. Brassicce var. macrospora,
which is reported here on cabbage and other cruciferous plants.
NOTES ON PARASITIC FUNGI. 32/
This can usually be told from the other leaf troubles of this
host by the brown spots, starting as black dots, forming con-
centric rings of development. The spots are about one-quarter
of an inch in diameter.
Leaf Spot, Cercospora Armoracia Sacc. Plate XVII, e.
The fruiting stage often shows as an inconspicuous upright
growth on the surface of the subcircular brown spots.
INDIAN CXJRRANT, Symphoricarpus vulgaris.
Powdery Mildew_, Microsphcera Symphoricarpi Howe. In
nurseries this proves a common trouble, covering the upper sur-
face of the leaves usually with a dense white growth of the
summer spore stage, and producing an abundance of the peri-
thecia on the upper surface or, more scattered, on the under side
of the leaves.
mis, Iris sps.
Leaf Blight, Heterosporium gracile (Wallr.) Sacc. This is
a very serious trouble of the Iris, especially of Iris Germanica.
The prominent elliptical spots appear scattered over the leaves,
.which often turn yellowish and die at the tips.
Rootstock Rot, Bacteria. Plate XIX, a. In one of the
nurseries, last season, this trouble was common on Iris Ger-
manica and /. cristata. Apparently the disease had been greatly
aggravated by burying the rootstocks too deeply when trans-
planted that spring". The wet season, too, was favorable for
the development of the trouble, which, according to the manager,
was unusually severe. The rootstocks were rotted off by a
wet bacterial rot, which sometimes extended up into the base
of the outer leaves. Apparently this is the same trouble that
has recently been described from Germany [Zeitschr. Pflanz-
krankh. 13: 129-44, 1903.] Dr. van Hall, who studied the
trouble there, found three organisms associated with the rot,
of which Bacillus omnivorus apparently was the chief. The
writer made no cultural studies.
Rust, Puccinia Iridis (DC.) Wallr. On the wild species
of Iris this is a very comrnon rust, but it was found only once
on a cultivated species. It produces the ordinary dusty reddish
pustules, thickly covering the leaves. So far only the uredo-
stage {Uredo Iridis DC.) has been found here.
22
328 CONNECTICUT EXPERIMENT STATION REPORT, I903.
IVY, BOSTON", Ampelopsis tricuspidata.
Leaf Spot, Phyllosticta Labrusccp Thm. This is apparently
the same as the leaf spot form of black rot of grapes.
KCELRETJTERIA, Kcelreuteria paniculata.
Red Knot, Nectria cinnabarina (Tode) Fr. Colortype 3.
This occurred in a nursery doing serious injury to this Japanese
tree. On the sunken, cankered areas reaching clear into the
wood, there was found an abundance of the small, spherical,
bright red perithecia of the fungus. There was some question,
however, whether winter injury did not form the starting point
of the trouble.
LAVATERA, Lavaiera sp.
Rust, Puccinia Malvacearum Mont. See Hollyhock.
LETTTJGE, Lactiica sativa.
Downy AIii.dew, Bremia Lactucce Regel. Lettuce, both in
and out of doors, is sometimes bothered by this fungus. It
produces brownish dead areas which usually show on the under
side whitish tufts of the fertile threads of the fungus. As it
is a trouble that thrives best in moist places, care in watering
greenhouse plants is helpful in controlling it. [Bull. 142, p. 9.]
Grey Mold, Botrytis vulgaris Fr. This causes a rotting or
spotting of the leaves, upon the dead portion of which the
fruiting stage develops as an erect greyish mold. It is common
in moist greenhouses and is apparently the same Botrytis that
develops on a great variety of plants under moist conditions.
The stem rot of onions, the grey mold of grapes and the fruit
mold of egg plants are possibly caused by different species.
Leaf Spot, Septoria consimilis Ell. & Mart. This can be
identified by the fruiting stage, which shows as very small
black dots in the spots or dead areas it produces on the leaves.
Like the other troubles, care in watering indoor lettuce and
the removal of diseased leaves as soon as they appear, will help
to keep it in check. It will pay the greenhouse grower never
to allow any wilted or dead leaves to remain either on the plants
or on the soil.
NOTES ON PARASITIC FUNGI. 329
LILAC, Syringa vulgaris.
Powdery Mildew^ Microsphcera aim (Wallr.) Wint. Every-
one has noticed this on the upper surface of lilac leaves. Both
spore stages are produced abundantly.
LILY OF THE VALLEY, Convallaria majalis.
Leaf Blotch. During the summer and fall the leaves of
this plant commonly become discolored with purplish blotches,
which often run together into large areas. So far no fungus
has been found in a fruiting condition on these leaves, but the
trouble appears to be of fungous origin.
LILY, WHITE DAY, Funkia siihcordata.
Anthracnose, ? Colletotrichum sp. Produces subcircular
brown spots with purplish borders.
LINDEN, Tilia sp.
Black Mold^ Fwnago vagans. The linden trees of a park
in Bridgeport were found coated on their upper surface with
this fungus, which gave them a sooty appearance.
MAHONIA, Mahonia Japonica.
Leaf Spot, Fhyllosficta Japonica Thm.
MAPLE, Acer sps.
Anthracnose, Glceosporium saccharini E. & E. Irregular
dead areas, often of considerable size, are produced by this
fungus, giving the appearance of sunburn.
Black Spot, Rhytisma acerinum (Pers.) Fr. On Acer
dasycarpum. This forms black, slightly elevated "finger
prints," about y^ inch wide, on the upper surface of the leaves.
The lower surface is often concave and not so dark colored.
The sac fungus producing these does not mature its spores
until some time after the leaves have fallen from the trees.
Leaf Spot, Fhyllosficta minima (B. & C.) Ell. (P. acericola)
On Acer dasycarpum, A. pseudoplatanus var. Causes reddish
or brownish circular spots about %. inch in diameter.
330 CONNECTICUT EXPERIMENT STATION REPORT, I903,
MARIGOLD, Tagetes sp.
Grey Mold, Botrytis vulgaris Fr. On blossoms. See
Lettuce.
MATRIMONY VINE, Lycnim vulgare.
Powdery Mildew, Erysiphecz undet. Conidia only.
MIGNONETTE, Reseda odorata.
Leaf Blight, Cercospora Resedce Fckl. Not infrequently
this fungus produces small whitish spots on the leaves.
Stem Rot, Rhisoctonia sp. In one greenhouse this was
found doing some damage to the plants. The stems were rotted
off at the base, the leaves turning yellowish. Where the leaves
came in contact with the moist ground, they also started to rot.
MUSK MELON, Cucumis Melo.
Anthracnose, Collet otrichuni Lagenarium (Pass.) Ell. &
Hals. See Watermelon,
Downy Mildew (Blight), Plasmopara Cubensis (B. & C.)
Humph. Plate XVHI, a-b. This trouble has been prominent
at least during the past three years, though last year it was not
nearly so serious as the year before. As it is a trouble that
comes and goes, this may indicate that it is on the wane again.
The disease first shows during the latter part of July or early
August, when large, brownish, angular spots appear on the
leaves. If the season is favorable, the leaves become thickly
covered with these, the intervening green tissue dies and the
leaf dries up on its stalk. In a very few days the trouble may
spread so rapidly that it kills practically all of the leaves. This
often occurs before any of the fruit matures, and what little
does ripen lacks flavor. In moist weather, by looking closely
at the under surface of the leaves with a magnifier, the fruiting
threads can be seen at the juncture of the green and dead
tissue, as a scanty, dark purple, upright growth. The color
is due to the very large purplish summer spores which are
borne on the ends of these fertile threads. The winter, or
oospores, have never been found, though the writer has searched
for them at all seasons of the year. It is not known how the
fungus passes the winter in this state. Possibly it does not
NOTES ON PARASITIC FUNGI. 33 1
winter so far north, or possibly it is carried over on greenhouse
cucumbers. Any curcubit is Hkely to be attacked by it, but so
far it has been observed here only on the common and
English cucumbers, on musk melons and rarely on water-
melons. During seasons when the trouble develops very seri-
ously, it is questionable if spraying yields any very striking
results with musk melons, though it does give good results
with cucumbers. During ordinary seasons, however, this, and
most of the other troubles of the musk melon, can be held in
check by thorough and repeated sprayings with Bordeaux. The
first application should be made as soon as the vines begin to
run. [Rep. 1899, p. 2.^]^ ; Bull. 142, p. 10.]
Leaf Mold^ Alternaria Brassicce var. nigrescens Pegl. {Mac-
rosporium cucumerinwn Ell. & Ev.) This fungus also pro-
duces brownish spots on the leaves that can scarcely be
distinguished by the naked eye from those of the preceding
fungus. It occurs also on the watermelon. While not an
uncommon trouble, it is not usually so serious as the downy
mildew. The treatment is the same. [Reps. 1895, p. 186;
1896, p. 267; 1898, p. 233; 1899, p. 272; Bull. 142, p. 10.]
Scab, Cladosporium cucumerinum Ell. & Arth. {Scoleco-
trichum melophthorimi Pr. & Del., Cladosporium cucumeris
Frank.) Plate XIX, b. This has been reported several times in
this country on cucumbers, and in Europe on both cucumbers and
musk melons. Last season it was found in this state, on both
hosts, but doing most injury to melons. It appeared about the
first of August, producing sunken areas on both stems and fruit.
The mycehum produces these by collapsing the tissues and then
forms on the outside a dense olive growth of a summer spore
stage — the only one known. Apparently, the trouble thrives
only in very moist weather.
Wilt, Bacterial, Bacillus tracheiphilus Sm. Occasionally
occurs, doing damage ; see Squash. Bacteria also produce a
leaf spot trouble, but probably this is only another form of the
wilt disease. [Rep. 1898, p. 225.]
Wilt, Fungus, Neocosmospora vasinfecta (Atk.) Sm. In
appearance this is the same as the preceding, but the Fusarium
stage of the Neocosmospora fungus clogs up the water ducts
of the stem and produces the wilt. Apparently it is not as
common as the bacterial wilt. [Rep. 1898, p. 228.]
332 CONNECTICUT EXPERIMENT STATION REPORT^ IQOS-
Spray Injury. Bordeaux mixture sometimes slightly injures
the foliage. In these cases the leaves turn yellowish at the
margin and may die prematurely if severely injured. Occa-
sionally the fruit shows some distortion or the scar of the
blossom end becomes greatly exaggerated.
Sun Burn. Sturgis described a similar trouble which he
called leaf burn, and ascribed to a sudden disturbance of the
equilibrium between water absorption and evaporation. "When
cool, cloudy weather alternates with hot sunshine, it is frequently
noticed that the large leaves near the center of the hills turn
yellow at their margin. Later, these yellowed margins become
brown and dry and finally the whole leaf is diseased." [Rep.
1898, p. 228.]
MUSTARD, Brassica sp.
Leaf Mold, Alternaria Brassicce (Berk.)Sacc. See Cabbage.
OAK, Querciis sp.
Powdery Mildew, Microsphcsra quercina (Schw.) Burr.
The cultivated English oak, Querciis rohur, frequently has this
mildew on its leaves.
OAT GrRASS, Arrenathemm avenaceum.
Smut, Ustilago perennans Rostr. The smut destroys the
grain, but the fungus is not of economic importance since the
host is rarely grown here.
OATS, Avena sativa.
Black Stem Rust, Puccinia graminis Pers. Plate XIX, c.
This rust produces elongated outbreaks on the stems and leaf
sheaths. These are at first the reddish, uredo-stage, but later the
black, teleuto-stage. The stems are weakened by the action of
the fungus and badly rusted grain is apt to lodge. The bar-
berry is the host for the ascidial stage, but apparently the fungus
often skips this step in its life cycle. Black rust also occurs
here on red top and timothy. This rust very commonly occurs
with crown rust, and the injury they cause to the crop of oats
is sometimes considerable. Very little can be done to lessen
these troubles. [Rep. 1889, p. 174.]
NOTES ON PARASITIC FUNGI. 333
Crown Rust, Puccinia coronata Ccla. Plate XIX, d. This
is common on the leaves, producing first the small, dusty, red
uredo-stage, and later the blackish teleuto-stage firmly imbedded
in the tissues. These outbreaks are not nearly so elongated or
prominent as in the preceding. It is called crown rust because
the teleuto-spores have curious, horn-like projections.
Smut, Ustilago Avencs (Pers.) Jens. Plate XIX, e. This
forms the common, dusty, blackish masses that completely
destroy the grain. The covered smut, Ustilago levis, less com-
pletely destroys the grain, often being confined to the inner basal
parts ; neither is it as common here, -Both of these smuts can
be prevented by seed treatment with formalin or hot water.
[Bull. 142, p. 10.]
ONION, Allium Cepa.
Black Mold, Macrosporium Porri Ell. Apparently this does
more or less damage to onions. It is found on "blighted"
onions and probably is partially responsible for the trouble.
Thaxter describes and figures this in the Report for 1889, p. 161.
The fungus probably belongs under the genus Alternaria rather
than Macrosporium, if these two genera are distinct.
Black Spot, V ermicularia circinans Berk. Plate XX, a. It
is on the stored onions that this trouble becomes prominent.
Black blotches, made up of the small black fruiting pustules,
appear on the outer dry coats of the onion and gradually work
through a few beneath. While not causing a rot, this trouble
seriously affects the appearance of the onion, especially the white
varieties, and thus lessens their market value. So far the only
means of lessening it is the best care in drying and storing the
crop. Some have advocated the use of air-slaked lime scattered
over the onions, but no definite experiment has been undertaken
to show the value of this. [Rep. 1889, p. 163 ; Bull. 142, p. 11.]
Downy Mildew, Peronospora Schleideni Ung. Thaxter
found this fungus causing serious injury to the onions at
AVethersfield in 1889. " It has not been seen by the writer, though
it probably still causes trouble occasionally. Usually the whitish
growth of the mildew is not very prominent and may be
obscured by the presence of the black 'mold fungi. Through
the action of the mycelium, whitish or yellowish spots are pro-
duced in the tissues and the injury may become so severe that
334 CONNECTICUT EXPERIMENT STATION REPORT, I903.
a blighting of the vines results. The fungus occurs in the fields
as early as July. Spraying experiments conducted in Vermont
showed that the trouble could be partially controlled in this way.
RoT_, Bacterial. Stored onions are sometimes destroyed by a
soft rot due to bacteria. Sometimes the whole onion rots or
only certain layers may go. If the outer ones are rotting, they
give a slippery feeling upon pressure with the hand. Maggots
often accompany or follow this trouble.
Smut, Urocystis Cepulce Frost. This produces black, dusty
pustules on the leaves and bulbs. It may be found early in
May on the seedlings or late in the fall on the mature bulbs.
The former are often killed outright and the stand seriously
affected. The smut may become established in the soil and then
it becomes more and more difficult to raise onions on this land.
Considerable land valuable for onion culture has become unavail-
able for this purpose. It has been found that the sets do not
smut, to any great extent, and that seed onions germinated in
free soil and later transplanted to the infected soil also remain
nearly free from smut and that the transplanting increases their
size. Preliminary experiments by Thaxter and later work by
Stewart, of New York, and Selby, of Ohio, show that the
treatment of infected soil with certain chemicals will also lessen
the amount of smut. One of the most feasible treatments seems
to be the use per acre of lOO lbs. of sulphur, thoroughly mixed
with 50 lbs. of air-slaked lime, which is drilled into the rows
with the seed. Another remedy is sprinkling formalin over
the seed before covering. Ground lime, drilled into the soil at
the rate of 75 to 125 bushels per acre, has also been used.
[Reps. 1889, p. 129; 1890, p. 103; 1893, p. 99; 1895, p. 176;
Bull. 142, p. II.]
Stem Rot, Botrytis sp. Plate XX, b-c. In Europe tj;iere is
a Botrytis bulb rot of onions and hyacinths that is possibly
the same as that described here. It is known there in its perfect
stage as Sclerotinia hulhorum. This trouble has occasionally
occurred in Connecticut before, but apparently never so seriously
as during the past two years. There is a possibility that it is
not specifically different from the common Botrytis trouble of our
greenhouse plants. The same trouble has been reported before
by Halsted, of New Jersey, and during the past two years has
occurred also in Massachusetts and, perhaps, elsewhere. Only
NOTES ON PARASITIC FUNGI. 335
the Southport White Globe seems to have suffered very severely
from the rot. This variety is largely grown in Connecticut
along the Sound from Green's Farms to Guilford. The onion
growers of Green's Farms and Southport have suffered espe-
cially. In 1902 their loss was estimated at least $50,000, and in
1903 the crop did not nearly pay expenses. Some growers
stopped sending their onions to market, since the returns per
barrel paid little more than the freight. One grower near
Branford was able to market only about 400 bushels out of
1,200 harvested, but these brought him very high prices.
The stem rot does not appear until after the onions are stored
in the fall. Crops tfiat were supposed to be in a fair shape
when stored have rapidly disappeared with the trouble in
October and later. The onions are sorted and the good ones
sent to the market, but apparently these rot very seriously in
transit. The trouble is called stem rot, because it begins at
the stem end of the onion, which becomes soft to pressure at
this place due to the rotting of the inner layers. The rot does
not seem to usually spread from onion to onion, since the outer,
drier layers are generally the last to rot. Plate XX, b, shows
the top view of a rotting onion, while a cross section of the
same onion is shown in Plate XX, c, where it is seen that only
a few of the inner layers have rotted. Upon the exterior, drier
layers, there often develops a dense growth of the olive-grey
fertile threads of the summer stage. With these are sometimes
found the small black sclerotia, or resting condition of the
.mycelium, that carry the fungus over the winter and apparently
in the spring develop the Botrytis stage. A Sclerotina or asco-
stage has not been seen here. According to the writer's observa-
tions, this fungus in its Botrytis stage spreads as a para'site on
the green leaves and on the blossoms in the fields as early in
the season as July. It causes yellowish spots on the leaves
and blasts the flowers. Wet weather is especially favorable
for its development and this accounts for the unusual injury
during the past two seasons. Wet weather, when the onions
are drying in the field, undoubtedly is very favorable for the
development of the mycelium into the bulbs from the drying
stems ; however, it is only after their storage that the real stem
rot begins. Probably a moist fall after the storage also aggra-
vates the trouble.
336 CONNECTICUT EXPERIMENT STATION REPORT, I903.
So far no remedies have been tried to prevent the trouble.
Unusual care in curing and storing the crop apparently does not
stop it. The character of the land, whether new or old in onion
culture, seems to have had little influence. The very general
prevalence of the disease points to the wet seasons as the chief
■factor for its development, ' and if a dry season should now
follow, the chances are that the trouble would lessen very
greatly. Attention should be called to the old rotting onions
as a means of carrying the fungus over the winter by means
of the black sclerotia. These onions should not be used as a
fertilizer on the land. The fact that the fungus occurs in
summer as an active parasite on the plants indicates that pos-
sibly sprkying, by keeping the plants free from it during the
growing season, may lessen the chances of the bulbs rotting
late. If onions are sprayed, the first treatment should be given
very early in July. Resin Bordeaux will probably prove the
best fungicide to use, since the ordinary Bordeaux may not
adhere readily to the plants. The sprayings should be repeated
at least three times. This treatment is recommended only as a
possible remedy. [Bull. 142, p. 11.]
Yellow Leg or Black Mold^ Macrosporium parasiticum
Thm. This trouble is caused by a close relative of the fungus
described under Black Mold. Thaxter found it often associated
with the Downy Mildew, but he considered it a true parasite.
It was found in 1902 by the writer, doing considerable damage
to seed onions in the vicinity of Milford. Conspicuous yel-
lowish or whitish areas are produced on the leaves and these ,
become coated with a luxuriant black growth of the fruiting
mold. Spraying ought to prevent this trouble.
ORCHARD GRASS, Dactylis glomerata.
Ergot, Claviceps sp. The sclerotia are smaller than those of
the rye ergot.
PARSLEY, Petroselinum sativum.
Leaf Spot, Septoria Petroselini Desm. Under the action of
this fungus the leaves, or parts of them, turn whitish and
become speckled with the minute black spore receptacles imbed-
ded in the tissues. More rarely the fungus produces distinct
circular whitish spots in the green tissues. A variety of this
fungus occurs on celery.
NOTES ON PARASITIC FUNGI. 337
PARSNIP, Pastinaca sativa.
Leaf Blght_, Cercospora Apii var. Pastinacce Farl. This
is only a variety of the common leaf blight of celery. It has
not been found doing any considerable injury to the parsnip.
PEA, Pisum sativum.
Leaf Spot, Ascochyta Pisi Lib. While this is a very com-
mon trouble with peas it is only occasionally that it causes severe
injury. Roundish or angular spots are produced on both the
leaves and pods. These are about one-quarter of an inch or less
in diameter and usually have a distinct narrow purplish border.
[Rep. 1899, p. 280.]
Powdery Mildew, Erysiphe Polygoni DC. The powdery
mildew is likely to be found on the peas late in the season after
they have passed their prime. Sometimes, however, it comes
earlier and causes more severe damage. The leaves, stems and
fruit become coated with a more or less prominent whitish pow-
dery coating of the mycelium and summer spores ; later, the
small, blackish perithecia of the asco-spores are produced.
Spraying with potassium sulphide should control the trouble.
PEACH, Prunus Persica.
Bacterial Spot. During the past season, leaves of peach
were received from an orchard in Pomfret that were covered with
small, reddish brown, angular spots less than one-eighth of an
inch irf diameter. An examination of the diseased tissues under
the microscope showed an abundance of bacteria, which were
apparently the cause of the trouble. The spots were very
similar to those produced on the leaves by the scab fungus or
by spraying injury, and the tissues showed a tendency to fall
out, giving a shot-hole effect. As 1903 was a season very
favorable for the development of bacterial troubles, in normal
seasons this bacterial spot may not prove serious.
Brown Rot, Sclerotinia fructigena (Pers.) Schrt. Plate
XXI, b. The fruit is the part of the host most severely injured
by this fungus. About the time of ripening it may begin to
decay, and if the weather is moist, the brown rot spreads rapidly.
The ordinary rot of the peaches bought in the market is caused
by this fungus. The brown rotten areas rapidly involve the
338 CONNECTICUT EXPERIMENT STATION REPORT, I9O3.
entire peach, and the summer fruiting- stage usually shows in
the small, dusty, closely packed pustules breaking out on the
surface. The disease is not confined to the fruit, but the young
twigs and sometimes the leaves are killed. In some cases the
mycelium apparently passes down into the branches from the
diseased fruit. In wet springs the fungus also sometimes
blasts the blossoms. Brown rot is one of our most injurious
fungous foes, since in wet years thousands of baskets of peaches
are destroyed by it. Usually it is most troublesome with the
early varieties. Plums and cherries are also seriously affected
by it, while apples, quinces and pears are less subject to
this rot. The fungus passes the winter in the diseased branches,
and also in the mummied, rotted fruit; the mycelium in these
giving rise to new summer spores in the spring. Norton, of
the Maryland Experiment Station, has recently found the
mature stage of the fungus developing from the mummied fruit
buried in the ground. This consists of a narrow pedicle expand-
ing above the ground into a saucer-shaped receptacle that con-
tains the winter or asco-spores. This then is another means
of carrying the fungus from one season to another. So far,
this stage has not been found in Connecticut.
It is evident that all rotten fruit should be destroyed by fire,
and that all mummies should be carefully removed from the
trees and the ground each season after the harvest time. Dur-
ing the ripening period, all rotten fruit should be gathered
promptly, in order to check the spreading of the trouble.
Where fruit sets very abundantly, the common practice of
thinning also serves to keep down the trouble later. A good
many spraying experiments to prevent brown rot have been
recorded, some of which evidently have proved successful ; but
it is a difficult disease to combat in this way, both because of
the rapidity with which it spreads in moist weather, and because
of the injury that is likely to result to the foliage from the
use of fungicides. Where spraying is to be tried, perhaps the
best treatment would be a winter spraying with Bordeaux,
given as for leaf curl, followed by two or three sprayings
about picking time with potassium sulphide or copper acetate.
[Reps. 1889, p. 171 ; 1893, p, 95; 1894, p, 138; 1898, p, 261;
1900, p. 232 ; Bull. 142, p. 12.]
Crown Gall, Dendrophagus globosus Toum. See Plum.
NOTES ON PARASITIC FUNGI. 339
Crown or Foot Rot. This trouble is confined to the region
of the tree near the juncture of the stock and scion, usually just
below the ground. The most peculiar character is the ease with
which the trees are broken off at this place. By pushing them
from side to side by hand, they will often crack off sharply and
sometimes they are even broken off by the winter winds. The
trouble is not usually found in the nursery, but it has been seen
in young orchards only set out one or two years. It is most
conspicuous, however, in the older orchards. The trunk or
roots become enlarged at the crown, so that it is sometimes
called "club root." Upon breaking off the trees the woody
growth is seen to be abnormal here, having become spongy
and brittle and thus allowing easy fracture. On this account
it is known also as "spongy root." The cortex is abnormally
developed and appears diseased. The trees usually show the
trouble some years before dying. They cease to grow; the
foliage gradually becomes scantier, and often has an unhealthy
appearance. The trouble is not uncommon in the peach orchards
of the state, and was first described by Sturgis in the Report
of the Pomological Society for 1901, p. 235. The owner of one
orchard of about thirty acres, examined by the writer, stated that
he had removed one year about 400 trees and since then a few
trees had been taken out each year. It is a question whether
the trouble is contagious, since young trees set out in the place
of those removed do not seem to be especially troubled. The
cause of the disease is not surely known. Most probably it is
due to a fungus developing in the bark and wood, producing
these abnormal and diseased conditions of the tissues. Sections
of the cortex have shown the presence of mycelium in the dis-
eased tissues, but it is possible that this may have come in late
as a saprophyte. The other possible explanation is that the
morbid conditions result from too great moisture in summer,
followed by injury from severe cold in winter. Most growers
remove the trees as soon as found since they never amount
to much.
Dead Limb Fungus, Cytospora Persiccu Schw. This fungus,
apparently, is never the cause of disease, but it is frequently
present on the dead limbs as a saprophyte. Sometimes a dead
tree is entirely covered with its outbreaks. These show as small
white pustules.
340 CONNECTICUT EXPERmENT STATION REPORT, I9O3.
Leaf Blight, Cercosporclla Persica Sacc. The name frosty
mildew describes more aptly the appearance of the fungus. It
produces yellowish or reddish areas on the leaves, showing the
fruiting condition on the under surface usually as a conspicuous
white growth. Thaxter, in the Report for 1889, p. 173, records
the defoliation of orchard trees at Deep River by this fungus.
The writer has observed it only once, where it was doing a
little damage to nursery trees.
Leaf Curl, Exoascus deformans (Berk.) Fckl. Colortype
7. Leaf curl is one of the earliest appearing diseases of the
peach, showing soon after the leaves come out. It kills the
entire leaf, or the greater part of it, usually from the tip down-
ward. The leaf turns yellowish or reddish brown, and becomes
more or less irregularly curled or wrinkled. Often a whitish
bloom is seen on the diseased area. The worst infected leaves
drop off, so- serious defoliation may often take place. The
trouble may be prevented largely by a single spraying with
Bordeaux mixture just before the buds begin to swell in the
spring. In very wet seasons a second application, with the half
strength mixture, should be applied just after the petals fall.
The winter treatment with the lime, sulphur and salt for the
scale is said to also check this trouble somewhat. [Bull. 142,
p. 12.]
Powdery Mildew, Sphaerotheca pannosa (Wallr.)' Lev. In
nurseries where the trees are crowded closely together, this
fungus is found sometimes causing trouble. Occasionally it is
also found on trees in the orchard. The young leaves and the
twigs become covered with an evident white felt of the mycelium
and summer spore stage, but the winter stage has not been
observed. Planting the trees less closely would no doubt be
helpful in preventing the trouble or spraying with potassium
sulphide should control it.
Scab, Cladosporimn carpophilum Thm. Plate XXI, a, c-d.
This fungus occurs on the fruit, leaves and twigs. It forms
the black, circular, superficial spots so commonly seen on the
fruit in the market. Very frequently these scabby spots pretty
thoroughly cover one half the surface, that which faced upwards
on the tree. When abundantly attacking the young fruit, it
may cause it to develop one-sided, or to crack open when mature,
thus exposing it to decay by the brown rot fungus. On the
NOTES ON PARASITIC FUNGI. 34 1
leaves, the fungus produces a reddish brown spotting of the tis-
sue, which later may drop out, giving a shot-hole effect. On the
young twigs it also produces conspicuous reddish brown spots
often with a purplish border. The mycelium lives over the
winter on the infected twigs and produces the summer spores
in the spring. The advantage of a winter or early spring
treatment on the dormant tree is readily seen. Several Con-
necticut orchardists report less scab in their orchards after spray-
ing with the lime, sulphur and salt mixture for the San Jose
scale. The treatment for leaf curl should also be of benefit for
this trouble. Winter treatment, however, will not wholly stop
it. Taking into consideration the few peaches harvested last
year, the scab was more injurious than usual. [Reps. 1894,
p. 138; 1896, p. 269; 1898, p. 261; 1900, p. 232; Bull. 142,
p. 12.]
Spray Injury. The experiments of Sturgis, Rep. 1900, p.
219, showed conclusively that there was danger in the use of
fungicides on the mature foliage, at least in Connecticut.
Bordeaux mixture, which is the fungicide commonly used, will
produce a leaf-spotting and shot-hole effect very like that of
the scab fungus. The worst injured leaves fall off, so it is
possible to completely defoliate the tree. The writer found that
there was even danger in the use of the half strength solution.
Potassium sulphide, apparently, is the safest fungicide to use
on the mature leaves.
Winter Injury. Plate X, a. The sudden freeze in Decem-
ber, 1902, killed the fruit buds very generally and also injured
the wood slightly. This darkening of the wood often showed
in spots in a cross section of the branch and became more
evident toward the ends of the twigs, sometimes ending in a
dead twig. The growth of new wood made the next year was
good, though not so great where the injury was very manifest.
The winter of 1903-4 was very much more injurious. While
the trees went into the winter in better condition than the pre-
vious year, the continued and" severely cold weather made its
influence felt in a number of orchards. The injury to the
fruit buds, apparently, was not so great as the year before. The
chief injury was to the wood of the trees; this showed in the
blackening or darkening of the wood clear down to the snow
line. The few inches of the trunk next the ground, protected
342 CONNECTICUT EXPERIMENT STATION REPORT^ I9O3.
by the snow, appeared uninjured. As yet, the bark does not
show the effect of this injury, and no cases of its girdhng was
observed, as with apples the previous year. Most orchards
escaped this injury, while others in the same locality but lower
down, were very severely injured. Many trees will no doubt
have to be cut out ; others may pull through with a severe prun-
ing. What future troubles may result to trees severely injured,
if left standing, is not known.
Yellozvs. This is now considered a physiological trouble, due
to certain enzyms or ferments acting on the tissues and dis-
arranging their normal functions. It is a contagious trouble.
No doubt many sickly peach trees present symptoms that may
be mistaken for yellows by some. The general characters of
the disease are as follows : A premature ripening of the fruit,
which becomes streaked with red and is of very poor quality;
a premature development of the winter buds, giving rise to
excessive branching on the new shoots ; the development of
adventitious buds into elongated sickly water sprouts ; finally,
a scantier and sickly yellowish development of the foliage. The
usual method followed with this trouble is to grub out the trees
as soon as discovered, and plant new ones in their places. [Rep.
1893, p. 92; Bull. 142, p. 137.]
PEAR, Pirus communis.
Bitter Rot, Glomerella rufomaculans (Berk.) Sp. Sz: von. Schr,
Occasionally found on this host but not very injurious. See
Apple.
Black Mold, Fumago vagans Pers. This fungus lives in
the honey dew secreted by lice, and, while often forming a
conspicuous coating on the leaves, it is hardly to be feared in
itself. Last year the seasonal conditions were unusually favor-
able for the propagation of the pear psylla and the green apple
louse, and these insects did serious damage to their hosts.
Early in June, developing in the honey dew of these insects,
there appeared on the pear and apple leaves and twigs a con-
spicuous coating of the black mold, which remained prominent
during the season. Some growers mistook this for the cause
of the injury, which really resulted from the attack of the lice.
Black Rot, Sphcsropsis Malorum Pk. Occasionally occurs
on twigs, fruit and leaves. See Apple.
NOTES ON PARASITIC FUNGI. 343
Brown Rot, Sclerotinia fructigena (Pers.) Schrt. Not a
very serious trouble on this host. See Peach.
Fire Blight, Bacillus amylovorus (Burr.) De Toni. This
bacterial disease is the most serious enemy of the pear. It was
with this that bacteria were first proved to be the agents of
disease in plants. Insects visiting the blossoms accidentally
carry the germs to the nectar, where by multiplication they
gradually work down into the young twigs and cause their
death in late spring or early summer. Blighted twigs, a foot
or two in length, with the blackened, dead leaves still adhering,
occur commonly. Cankered areas also occur in the bark of
the older branches or the main trunk. Sometimes sticky exuda-
tions of the bacteria may be found on these diseased places,
and are thus exposed to distribution by insects. Some growers
believe that blight occurs more commonly on cultivated trees
than those left in sod. The only treatment is thorough prun-
ing. This should be done in winter, when the germs are less
likely to be distributed, and care should be taken to cut off the
limbs below the disease. The occasional dipping of the pruning
knife into corrosive sublimate, to kill adhering germs, is also
advocated. Cankered areas may be scraped and painted.
Blight occurs also on the quince, apple and rarely on the plum.
[Rep. 1894, p. 113; Bull. 142, p. 13.]
Leaf Blight, Entomosporium maciilatum Lev. Sometimes
this causes serious injury to the leaves and fruit. See Quince.
Leaf Spot_, Septoria piricola Desm. So' far, this has been
found only sparingly here. The leaves become more or less
covered with small, greyish, subcircular or angular spots with
purplish borders. It may be prevented effectually by the usual
treatment for pear scab. [Bull. 142, p. 13.]
Pink Mold, Cephalothecuim roseum Cda. Occasionally
causes rot in ripe stored pears. See Apple.
Rust, Gymnosporangium glohosum Farl. Thaxter reported
the secidial stage of this rust [Rep. 1890, p. 98] on Japanese
varieties, where it was doing considerable damage. See Apple.
Scab, Venturia pirina (Lib.) Aderh. Like apple scab, the
parasitic summer stage (Fusicladium pirinum) of this fungus
is now known to be connected with a saprophytic asco-spore
stage that develops on fallen leaves. Pear scab is closely related
to apple scab and very similar in appearance, and the treatment
23
344 CONNECTICUT EXPERIMENT STATION REPORT^ 1903-
for its prevention is practically the same. See Apple. [Reps.
1889, p. 173; 1893, p. 73, 90; 1894, p. 135; Bull. 142, p. 13.]
Sooty Blotch^ f Phyllachora pomigena (Schw.) Sacc. This
is not nearly so troublesome on the pear as on the apple, q. v.
PEONY, PcBonia sps.
Scab, Cladosporium Pceonice Pass. This trouble forms very
conspicuous blotches, often over an inch in diameter, on the
leaves. Usually these start at the border and extend inward.
They are purplish on the upper surface and reddish brown
beneath. It was found once doing damage in a nursery.
PEPPERS, Capsicum annuum.
Anthracnose, Collet otrichum nigrum Ell. & Hals. In the
Report for 1899, p. 282, Sturgis states that he found this
fungus destroying 25 per cent, of the fruit in certain fields. It
develops light brown, rotten areas on the fruit, which greatly
enlarge and ruin the fruit. The fruiting stage shows on these
rotten spots as numerous minute black pustules. Spraying
experiments, conducted by Halsted, of New Jersey, did not
prevent the disease very successfully. The rotten fruit, as soon
as it appears, should be picked and carried away.
Anthracnose, Gloeosporium piperatum Ell. & Ev. The
writer has found this sparingly in the fields. It produces a rot
of the fruit like the above, but the fruiting stage shows as
minute pinkish globules.
Black Mold, Macrosporium commune Rabh. On the rotten
areas of the fruit, one sometimes finds this fungus developing
a luxuriant olive-black moldy growth. Apparently, it is only a
saprophyte.
Grey Mold, Botrytis sp. The grey mold that affects a great
variety of plants also produces rot on the peppers, and develops
a dense, erect growth of the olive-grey fruiting threads on them
in moist weather.
PHLOX, Phlox sps.
Leaf Blight, Septoria sp. Forms large, irregular, whitish
areas in which are thickly embedded the small black spore
receptacles.
NOTES ON PARASITIC FUNGI. 345
Leaf Spot^ Cercospora omphacodes Ell. & Holw. Forms
small whitish spots with purplish borders.
Powdery Mildew^ Erysiphe cichoracearum DC. Plate
XXIV, a. This is a common trouble with phlox, the mycelium
thickly coating the stem and leaves. Both spore stages occur.
The trouble could probably be kept in check by spraying.
PINK, SWEET WILLIAM, Dianthus barbatus.
Stem Rot^ Rhizoctonia sp. See Platycodon.
PLATYCODOIT, Platycodon grandiflorum.
Stem Rot, Rhizoctonia sp. The stems gradually rot at the
ground, and the plants wilt and often die as the result. The
fungus lives in the soil and appears year after year, killing
some of the stems. The trouble may spread to neighboring
plants, as it occurs on Sweet William, mignonette, carnations, etc.
PLTJM, Prunus sps.
Black Knot, Plowrightia morbosa (Schw.) Sacc.-- Plate
XXIV, c. The black, gall-like excrescences that occur on the
limbs are familiar to every one. Ordinarily, they form an
elongated irregular enlargement two or three times the thickness
of the small branch. The surface is very uneven with minute
elevations, indicating the spore cavities. The knots sometimes
attain considerable size or produce distortion in the large
branches. By the thorough pruning of affected branches, the
trouble can be held in check. In the nursery this can be supple-
mented with spraying. The mycelium penetrates deeply into
the wood and causes dark streaks; in pruning, all this should
be removed. Where large branches are removed, it is best to
paint over the cut surfaces. In some cases entire trees need to
be cut down. The Japanese varieties now seem to knot as
badly as any of the others. Wild and cultivated plums and
wild cherries are subject to the same trouble. While always
present, it seems to have developed more vigorously than usual
during the past two years. [Reps. 1889, p. 176; 1893, p. 94;
Bull. 142, p. 6.]
Brown Rot, Sclerotinia fructigena (Pers.) Schrt. A serious
trouble of this host. See Peach. [Rep. 1889, p. 176.]
346 CONNECTICUT EXPERIMENT STATION REPORT, I903.
Crown Gall_, Dendrophagus blobosus Toum. Plate XXIV, b.
So far this has been found here chiefly in nurseries. The gahs
are usually on the lower part of the stem near the ground, or
on the roots. They are morbid outgrowths of the tissues,
usually subspherical in shape and about an inch or two in diame-
ter. Sometimes they practically encircle the crown, girdling
the tree. Professor Toumey made a study of this trouble on
the almond in Arizona and ascribed it to a new species of
slime mold. Nursery stock showing any signs of these galls
should be rejected. The same trouble is found here in nurseries
on the peach, and the same or similar troubles occur on rasp-
berry and apple. [Bull. 142, p. 14.]
Fire Blight, Bacillus amylovorus (Burr.) DeToni. In the
Report for 1894, p. 117, Sturgis described a bacterial trouble
of plums found doing damage in an orchard at Hartford. It
was not known at that time whether the trouble was the same
as pear blight, but later study by Jones, of Vermont, seems to
show the identity of the two.
Leaf Curl, Exoasctis mirabilis Atk. Sturgis records this as
doing, damage in an orchard in New London in 1895. The
trouble is somewhat similar to peach curl, except the young
branch, as " well as the leaves, becomes distorted into an
irregularly thickened body. The injury to the leaves usually
extends from the base up. The same treatment given for peach
curl should be used for this.
Leaf Spot, Cylindrosporium Padi Karst. This does not
occur so commonly on the plum as on the cherry, q. v.
Plum Pocket, Exoascus Pruni Fckl. So far this has not
been recorded from this state, but is included here in the hope
that some one will send in specimens. It is caused by one of
the curl fungi, which attacks the young plums, forming elon-
gated, inflated bodies.
Powdery Mildew, Podosphcera oxyacanthce (DC.) DeBy.
So far this mildew has been found only in its conidial form,
producing whitish growth on the leaves. Apparently it is not
common.
Scab, Cladosporium carpophilum Thm. This has been found
here only on wild plums, but no doubt it occurs occasionally
on the cultivated sorts. See Peach.
Shot-hole. Spraying and certain fungi may produce shot-
NOTES ON PARASITIC FUNGI. 34/
hole troubles in the foliage of plums, but in most of the cases
examined these seemed to have had other agents ; at least, the
trees were not sprayed and no signs of a fungous agent were
found. Insects are probably responsible in some cases, and it is
barely possible that, as in the case of the peach, bacteria cause
the trouble. Some botanists have attributed it at times to
weather conditions. The plum seems to resent any injury to
the foliage by dropping out the injured tissue.
POPLAR, Populus sps.
Anthracnose, Marsonia Castagnei (Desm. & Mont.) Sacc.
The white poplar, Populus alba, is attacked by this fungus. It
produces reddish brown, subcircular spots on the upper surface
of the leaves ; the spots may become so numerous that they
merge into one another. The spores ooze out through very
small rifts in these spots.
Canker. Nurserymen complain .of a trouble of the Carolina
poplar that is apparently of fungous origin and produces can-
kered places in the bark and wood, especially at the base of the
young branches.
Rust, Melampsora populina (Jacq.) Lev. This is a common
trouble occurring on the leaves of a number of the poplars. The
uredo-spores break out as dusty, reddish pustules, but the teleuto-
spores are permanently embedded in the tissues and mature often
after the leaves fall to the ground.
POTATO, Solanum tuberosum.
Anthracnose, V ermicularia sp. After potato vines die,
especially if blighted, this common saprophytic fungus almost
always appears on the stems, showing its fruiting stage in
numerous, minute black tufts.
Blight or Downy Mildew, Phyfophthora infestans DeBy.
Plates XXII, d, XXIII, a-b. Any dead potato vine is likely
to ,be called blighted by the general observer. This trouble,
however, does not appear, usually, until about the middle of
July or later. Wet weather, of several days duration, any time
from the first part of July till the middle of August is very
likely to bring it into prominence, whole green fields suddenly
turning brown, the vines dying in a few da3's. A careful exam-
ination of these fields, however, would show its presence, in
348 CONNECTICUT EXPERIMENT STATION REPORT^ I903.
an inconspicuous way, some time before this. At first, prom-
inent black spots appear at the tips or margins of the leaves.
Careful examination on the under side shows a slight whitish
growth at the juncture of the green and diseased tissue. This
is the summer spore stage of the fungus, and it is by the quick
germination of the spores, in drops of moisture, that the disease
rapidly spreads. The black spots soon envelop the whole leaf-
let, the leaves die, and soon there remain only the upright
stems bearing the inconspicuous dried up foliage. The fungus
occasionally appears on the green stems, but usually these die
only as the result of the death of the leaves. The writer has
rarely found the fungus on the tubers, but it apparently passes
the winter in them, since the mature or oospore stage has never
been surely found. The rotting of the tubers may or may not
follow the blighting of the vines. This rotting, apparently, is
due to other agents;, namely, bacteria and the Fusarium fun-
gus, q. V.
By thoroughly spraying the vines with Bordeaux mixture,
the blight can be largely prevented, or so delayed that the yield
of tubers is greatly increased over that of unsprayed fields.
The writer has this subject under investigation to determine,
if year after year, spraying potato fields in Connecticut is a
paying operation. The results of two years work indicate that
it is profitable when the work is done thoroughly and on time.
In one case the sprayed rows gave twice the yield of those
unsprayed ; in another case the yield was a third greater ; in
a third case, where the vines were very imperfectly sprayed,
the increase, if any, was lost through rotting. The first spray-
ing should be given before the first appearance of the trouble,
about the 7th to the 15th of July, according to the season; the
second and the third should follow as the sediment wears off
the leaves. If rightly placed, three sprayings will ordinarily
suffice, but the vines should be well protected by the sediment
until about the first of September. It is very important that
the vines be thoroughly covered with the spray when the blight
zveather comes on and it is usually best to immediately follow
this weather with another spraying. The best apparatus for
spraying is a two-wheeled cart or light wagon that will straddle
two rows, allowing the horse to walk between, and the com-
mon barrel spray pump mounted in it, having two leads of
NOTES ON PARASITIC FUNGI. 349
sixteen foot hose provided with double nozzles. One man
drives and pumps, and two men follow behind the cart, each
spraying three or four rows. The foliage should be well
drenched with the mixture, using two or three barrels per acre.
In the writer's experience, geared power sprayers are not satis-
factory, since with these the foliage can not be properly covered
with the spray. [Reps. 1889, p. 173, 176; 1890, p. 102; 1892,
P- 39; 1893. P- 7Z, 100; Bull. 142, p. 15.]
Dry Rot, Fusarium oxysporum Schl. (F. Solani (Mart.)
Sacc.) Plate XXII, b. Smith and Swingle, of the United
States Department of Agriculture, have lately shown this fun-
gus to be responsible for a wilt of vines, and for end rot and the
bundle blackening of the tubers. During the past season, many
vines wilted in this state before the middle of July. Possibly
this was caused by the fungus described here. After the downy
mildew killed the vines, there was general complaint of rotting
tubers, and the dry rot fungus, unquestionably, was partially
responsible for this. The rot did not do much damage until
after the vines were blighted, for very few of the potatoes dug
immediately after the vines blighted were rotted, while in adja-
cent rows, dug two weeks later, very many were rotten. There
was a great difference in the amount of rot in different fields, and
even in different parts of the same field. During the past
winter, the market potatoes have shown an unusual amount of
end rot and the bundle blackening. Sometimes, these potatoes
appear perfectly sound on the outside. Usually the end rot
begins at the stem end and gradually rots the tuber, often show-
ing the fungus as a whitish mold on the outside. The potato
shown in Plate XXII, b, was one taken from the field and placed
for a day or two in a moist chamber to develop the growth
of the mold on the outside, so it shows this more prominently.
Care in selecting seed potatoes free from this trouble and
spraying thoroughly for the blight are, perhaps, the best methods
for lessening the trouble. Season, in some way, seems to be an
important factor in determining the amount of rot, since in
1902 there was little of this trouble, while in 1903 it was very
common, yet, both years the vines blighted. Apparently, wet
weather, after the vines blight, develops the trouble most
vigorously.
Early Blight, Alternaria Solani (E. & M.) J. & Gr. This
trouble produces distinct, subcircular, brown spots about one-
350 CONNECTICUT EXPERIMENT STATION REPORT^ IQOS-
fourth of an inch in diameter on the leaves. The spots often
show faint concentric rings of development. Paris green may
burn spots on the foliage so similar to these that the two
injuries are not easily distinguished. So far as observed by
the writer, this trouble has not proved very serious in this state.
It usually appears early in the year, and is most common in
moist seasons. The tomato and egg plant are also hosts for it.
Rosette^ Corticium vagum var. Solani Burt. So far the
writer has not found this doing serious damage in Connecticut,
though it has been very injurious in several other states. The
trouble appears early in the season, dwarfing the vines or caus-
ing the foliage to become crowded into rosette clusters. Badly
infected vines may be killed outright. It is caused by the sterile
mycelium (called Rhisocfonia) of this fungus, producing cank-
ered or dead areas on the stems near the ground. The plants
sometimes send out new roots above these girdled places ; but
the effect in any case is to produce a crop of small potatoes.
Selection of good seed tubers followed with treatment in forma-
lin will prevent the disease if the potatoes are planted in unin-
fected soil.
ScAB_, Oospora scabies Thaxt. Plate XXII, c. Professor
Thaxter, while botanist of this Station, first found the cause
of the scabby or superficially corroded condition of potatoes so
common everywhere. This is due to a fungus, which on
freshly dug potatoes sometimes shows as a slight whitish mold
on the scabby places. It is known that this fungus becomes
established in the soil and the use of manure was shown by
Sturgis to greatly increase the number of scabby tubers. Seed
treatment with corrosive sublimate or formalin (see page 295 of
this report for directions) will prevent the scab if the treated
potatoes are planted on uninfected land. Beets, turnips, etc., are
also subject to scab. [Reps. 1877, p. 68; 1886, p. 79; 1890,
p. 81; 1891, p. 153; 1893, p. 102; 1894, p. 118; 1895, p. 166;
1896, p. 246; Bull. 103, p. 3; 142, p. 15.]
Wet Rot, Bacterial. Plate XXII, a. Durin'g the past sea-
son this trouble, together with the dry rot fungus, caused serious
rotting' of the tubers. The bacterial rot can be told from the
dry end rot by the slimy rotten condition of the tissues and
the very strong odor. Sometimes the same tuber has both
agents at work. The season early in 1903 was very unfavorable
for potatoes. This was due to the very dry May, followed by
NOTES ON PARASITIC FUNGI. 35 1
a very wet June. In some fields, as a result of these conditions,
a bacterial rot of the young stems developed, starting usually
below the ground and coming possibly from the decayed tubers.
It produced a black and often soft rot of the tissues of the
stem and caused the wilting, yellowing or death of the parts
above. This trouble was found worse in one field that had been
planted to potatoes immediately after plowing under green rye.
The stand obtained in this field was very irregular, and in the
fall the tubers were found badly rotted from the bacterial wet
rot. Very probably the bacterial troubles of the vines early in
the season and of the tubers later were caused by the same
organism, though no experiments were undertaken to prove this.
Paris Green Burn. Potato foliage is very often burned by
the use of too much Paris green or by its use without lime to
neutralize its caustic effects. The injury may occur as distinct
roundish spots', or it may show as a general searing of the mar-
gins, which die and dry up.
Tip Biirn. Dry warm weather of midsummer may cause
many of the leaves to die at their margins, which become dry
and rolled up, because the leaves are not able to check or replace
sufficiently the water lost through transpiration. It is a trouble,
however, that is more common and injurious in the drier states
of the Mississippi valley.
PRIMROSE, Primula sp.
Grey Mold, Botrytis vulgaris Fr. See Lettuce.
PRIVET, Ligustrum Japonicum.
Winter Injury. The freeze of December 9, 1902, seriously
injured the California privet by killing the branches. Very
few plants were killed outright, so that with vigorous pruning
the injured spots in the hedges were gradually obliterated dur-
ing the growing season.
PUMPKIN, Cucurhita sps.
Powdery Mildew, Erysiphe cichoracearum DC. The coni-
dial stage of this fungus occurs as a scanty whitish growth, in
patches on the upper surface of the leaves. Apparently, it does
little injury. No doubt, most of the troubles recorded here under
squash also occur on pumpkins but were not observed.
352 CONNECTICUT EXPERIMENT STATION REPORT, I903.
QTTINCE, Pirus Cydonia.
Black Rot, Sphm-opsis Malorum Pk. This often causes
serious rotting of the fruit as it nears maturity, usually starting
at the exposed blossom end. See Apple. [Reps. 1892, p. 43;
1893, p. 78; Bull. 142, p. 15.]
Brown Rot, Sclerotinia fructigena (Pers.) Schrt. This is
another fungus that produces rot in the ripening fruit, though
it is not nearly so injurious to this host as to the peach, q. v.
Fire Blight, Bacillus amylovorous ( Burr. ) DeToni. Blight
is very common on the quince. The leaves adhering to the dead
twigs have a decided reddish brown color, quite different from
the blackened leaves produced on the pear, q. v.
Leaf Blight, Entomosporium maculatum Lev. So far the
writer has observed this trouble only on the leaves and the
fruit. It is one of the most common and serious troubles of
this host. On the leaves it produces small, circular, brownish
spots, often showing the fruiting body as a black dot in the
center. When the leaves are badly infested, complete defolia-
tion may result before the end of the season. On the fruit, the
fungus produces a black spotting, and, especially with pears,
may cause it to grow one-sided or crack open. Thaxter was
one of the first to successfully prevent this trouble by spraying.
Bordeaux mixture should be applied, first just before the blos-
soms open, again after they fall and a third and fourth time
at intervals of about two or three weeks, according to the
weather. [Reps. 1889, p. 173; 1890, p. 99; 1891, p. 150;
1892, p. 42; 1893, p. 89, 91 ; Bull. 142, p. 13, 15.]
Leaf Spot, Hendersonia Cydonice Cke. & Ell. Occasionally
this fungus occurs in spots on the leaves. Sometimes it may
cause these, but often it merely develops on spots produced by
the black rot fungus. [Rep. 1893, p. 81.]
Rusts, Gymnosporangium glohosum Farl., G. nidus-avis
Thaxt., G. clavipes Cke. & Pk. The secidial or cluster-cup
stages of these rusts were reported by Thaxter and Sturgis on
the leaves and fruit of quince. Sometimes they cause serious
injury to this host. See Apple. [Reps. 1891, p. 161 ; 1894,
p. I37-]
Scab, Fusicladium sp. In the Report for 1893, p. 79, Sturgis
records the occurrence of a destructive fungus, similar to apple
scab, on the leaves of quinces at Tolland. The fungus was
not specifically determined and has not been reported since.
' NOTES ON PARASITIC FUNGI. 353
RADISH^ Raphanus sativus.
Downy Mildew, Peronospora parasitica (Pers.) Tul. See
Turnip.
Leaf Mold^ Alternaria Brassicce var. macrospora Sacc. This
forms numerous, small, blackish spots on the leaves and the
diseased tissue sometimes drops out. The smallest spots look
like insect punctures. See Cabbage.
White Rust, Albugo candidus (Pers.) Ktze. The small,
white blisters are formed on the under side of the leaves.
Upon rupture of the covering epidermis the spores are gradually
shed out as a dusty powder. While this fungus belongs with
the downy mildews, its gross and microscopic characters are
quite different, except with the winter spores. It probably
occurs on a number of the other cultivated cruciferous plants.
On wild pepper grass and shepherd's purse, the stems are often
considerably distorted by its presence.
RASPBERRY, Ruhus sps.
Anthracnose, Gl(£osporium Venetum Speg. Rarely this
forms minute white spots on the leaves, but on the stems it
occurs very commonly. Here it produces oval to circular white
spots, often merging into one another, with purplish borders.
It occurs most conspicuously on the new canes ; on the old
canes which carry it over the winter, the spots often become
sunken and less prominently colored. So far only summer
spores have been found. At pruning time the diseased canes
should be cut out as thoroughly as possible; and after the
disease has started on the new canes the worst of these might
be taken out. In the spring before the buds swell, the canes
should be sprayed with Bordeaux mixture; if repeated after
the leaves develop, care should be taken to get it on the young
canes chiefly. [Reps. 1889, p. 172; 1893, p. 98; 1899, P- ^74;
Bull. 142, p. 16.]
Cane Blight, Sphcsrella ruhina Pk. Plate XXIV, e. This
blight is not uncommon and causes considerable injury in the
writer's opinion. Apparently, it is most troublesome on the red
varieties. In its early stage the trouble might be mistaken for
a bacterial disease, so it is called blight. It first shows on the
young canes early in July, usually at the lower nodes from
which the leaves have fallen. It spreads downward from the
354 CONNECTICUT EXPERIMENT STATION REPORT, I903.
base of the leaf, or its scar, as an elongated purple blotch, which
shows very superficial injury to the bark. Rarely these blotches
start away from the node. The blotches gradually appear at
the higher nodes and slowly grow in size, sometimes completely
surrounding the stem. In the fall the diseased stems turn
whitish all over, and during the following winter the asco-spore
receptacles appear as small black specks, thickly scattered over
this whitened bark. The spores are matured by May and ready
for the infection of the young canes. So far no summer spore
stage has been found. The foliage of the infected canes is
usually streaked with yellow and crinkled. The treatment
described for anthracnose will apply here. [Bull. 142, p. 16.]
Crown Gall, f Dendrophagus glohosus Toum. Plate
XXIV, d. It is uncertain, as yet, whether this is exactly the
same as crown gall of plum or not. The raspberry often has
distinct knots very similar to those of the plum and peach, but
usually they extend in more or less merged excrescences along
the stem for some distance. Care should be used not to get
stock from a plantation containing the disease; and certainly
no plant showing it should be set out. Affected canes, when
discovered, should be removed. See Plum. [Bull. 142, p. 16.]
. Leaf Spot, Septoria Ruhi West. Common on leaves ; occurs
on wild species, as Ruhiis odoratus, etc. See Blackberry.
Orange Rust, Gymnoconia inter stitialis (Schl.) Lagerh,
Common on leaves of cultivated and wild species. See Black-
berry.
Wilt, Leptosphceria Coniothyrium (Fckl.) Sacc. The sum-
mer stage {Coniothyrium Fiickelii) has been described by
Stewart, of New York, as responsible for a serious cane blight
of raspberries in that state. The fungus causes dead areas in
the bark and wood, sometimes completely girdling the bark, so
that the parts above wilt and finally die. The fungus is some-
times associated with the blight fungus and their fruiting pus-
tules are not easily distinguished, except when the former have
shed out the spores in a dusty "brown coating. On old stems
this summer spore stage is often associated with an asco-spore
stage {Leptosphceria), which is believed to be merely another
stage of the same fungus. Both stages have been found here,
but as yet serious injury has not been traced directly to the
parasitic one. There has, however, been called to the writer's
NOTES ON PARASITIC FUNGI. 355
attention a trouble of blackcaps that may be caused by it.
The fruiting canes, about the time the fruit should begin to
turn, suffer from a serious wilt that dries up the berries. Spray-
ing experiments conducted by Stewart gave no beneficial results.
Yellozvs. Another trouble described by Stewart is the yel-
lows, which, apparently, is not uncommon in this state. The
foliage becomes crinkled and mottled with yellowish streaks,
and the fruiting canes often die before the fruit matures. This
seems to be a physiological trouble, possibly similar to the yel-
lows of peach. Spraying, with Stewart, gave no benefit. The
writer has found it worst on soil poor in nitrogen.
E>EB BUD, Cercis Canadensis.
Leaf Spot_, Cercospora cercidicola Ell. This is not uncom-
mon in nurseries. The leaves develop conspicuous reddish
brown or purplish, circular spots, one-quarter to three-quarters
of an inch in diameter.
RED TOP, Agrostis alba var. viilgaris.
Black Stem Rust^ Puccinia graminis Pers. Not uncommon.
See Oats.
Smut, Ustilago siricBfonnis (West.) Niessl. The smut is
found most commonly from May to July. It occurs on the
leaves, forming dusty outbreaks of the spores in elongated
lines. These often involve the whole blade, and the plants
are more or less stunted in their growth. After the spores
fall out, the foliage becomes more or less shredded. The fun-
gus also occurs here on timothy.
RHUBARB, Rheum Rhaponticum.
Leaf Spot, Ascochyta Rhei Ell. & Ev. Pie-plant leaves not
uncommonly have brownish spots of varying size and shape.
Very often these show no sign of the fruiting stage of a fungus.
In some cases, however, this fungus has been found.
ROSE, Rosa sp.
Leaf Blotch, Actinonema Rosce (Lib.) Fr. Plate XXV, c.
Greenhouse growers report this trouble more serious on the
hybrid tea roses. La France, Liberty, Meteor, than on the hybrid
356 CONNECTICUT EXPERIMENT STATION REPORT, I903.
perpetual. One or several purplish spots appear on the leaf-
lets. These sometimes attain half an inch in diameter. With
a lens, the mycelium can be seen radiating out from the center
on the upper surface of the spots. When badly infected, the
leaves turn yellowish and drop off. The' disease also occurs
on the hardy outdoor roses. Some of the greenhouse men
recommend the sulphur and oil paint on the heating pipes for
this trouble. Spraying with potassium sulphide may also prove
helpful. [Rep. 1893, p. 86; Bull. 142, p. 17.]
Leaf Spot, Cercospora rosicola Pass. This is not nearly so
common or injurious as the preceding. The spots are smaller,
less than one-eighth of an inch usually, and often have a lighter
center with a purplish border.
Powdery Mildews, SphcBrotheca Humuli (DC.) Burr., S.
pannosa (Wallr.) Lev. Plate XXV, a. The former mildew
is the common one seen in greenhouses. It forms a scattered,
mealy, or cobweb-like growth over the surface of the leaves,
causing them to become more or less crinkled. If badly
infected, they may fall off. Only the conidial stage occurs. Tea
roses are most likely to suffer ; among those most seriously
affected are Saffrano, Bon Silene, Bride, Bridesmaid, Niphetos,
Pierpont Morgan, Goldengate. Greenhouse men try to avoid
drafts and use care in watering to keep down this trouble.
Sulphur is very commonly sprinkled on the leaves, and when
the fires are started, sulphur and oil mixture is painted on the
pipes. The second mildew given above has been collected but
once, on an outdoor rambler rose. A thick felt of whitish
mycelium develops on the branches and more sparingly on the
leaves. The winter stage occurs imbedded in this. [Bull. 142,
p. 17.]
Rust, Phragmidium suhcorticium (Schrank) Wint. All
three stages occur on this host, most frequently on the leaves.
Sturgis notes injury to cultivated plants. [Report 1893, p. 86.]
RTJTA-BAGrA, Brassica campestris.
Powdery Mildew, Erysiphe Polygoni DC. Conidial stage
only. See Turnip.
RYE, Secale cereale.
Black Stem Rust, Puccinia graminis Pers. Common on the
stems. See Oats.
NOTES ON PARASITIC FUNGI. 35/
Ergot, Claviceps purpurea Tul. Plate XXV, b. This is
commonly found in volunteer rye. The conspicuous sclerotia,
or compacted masses of sterile mycelium, show as purplish horns
extending fronT the floral parts of the spike. It is from these,
after they have fallen to the ground and become buried, that
the asco-spore stage develops the next year. Ergot is poisonous,
and where abundant in grain, if eaten by cattle, may cause
serious trouble. A number of other grasses have smaller
sclerotia developing in their flower parts, probably, in most
cases, a species different from this.
Orange Leaf Rust, Puccinia ruhigo-vera (DC.) Wint. This
is common on the leaves, forming spore pustules similar to those
of the crown rust of oats, though the spores are very different.
[Rep. 1890, p. 98.]
Smut, Urocystis occulta (Wallr.) Rabh. Thaxter reported
this smut not uncommon, but not very injurious. The writer
has found it once in very limited quantity. The black, dusty
spore masses break out in lines, rather completely covering the
inner surface of the leaf sheaths.
SALSIFY, Tragopogon porrifolius.
Powdery Mildew, ? Erysiphe cichoracearum DC. Occa-
sionally this forms an inconspicuous growth of the conidial
stage on the leaves.
White Rust, Albugo Tragopogonis (Pers.) Gray. In one
market garden near New Haven this was found doing some
damage. The summer spores occur as white blisters on the
leaves and on the rupture of the covering epidermis become
scattered.
SNAPDRAGON", Antirrhinum ma jus.
Anthracnose, Colletotrichum Antirrhini Stew. In one
instance this was found seriously injuring Snapdragons grown
outdoors. The leaves and stems become rather abundantly
covered with whitish spots, usually oval in shape and marked
with a distinct purple border. Generally these are about one-
fourth of an inch in diameter, but by merging, may form an
extended area. Very small black dots in the center show the
fruiting stage of this imperfect fungus. In the fall, all of the
parts above ground should be cut off and the rubbish burned.
358 CONNECTICUT EXPERIMENT STATION REPORT, I903.
SOAPWORT, Saponaria officinalis.
Leaf Mold, Macrosporium Saponarice Pk. The fungus
causes whitish or greyish leaf spots, a quarter of an inch or less
in diameter. The fungus probably . belongs under Alternaria
rather than under Macrosporium.
SORGrHUM, Sorghum vulgare.
Grain Smut, Sphacelotheca Sorghi (Lk.) Clint. Usually
each grain of the entire panicle is changed into a slightly elon-
gated smutted body. The same smut occurs on broom corn,
but neither of these hosts are grown commercially in this state.
The trouble can be prevented by either the hot water or formalin
treatment of the seed.
Red Spot, Colletotrichum lineola Cda. The leaves become
streaked with elongated bright red spots which run together.
The fruiting stage shows on these as black pustules.
SPINACH, Spinacia oleracea.
Anthracnose, Colletotrichum SpinacicB Ell. & Hals. Pos-
sibly this may occur more abundantly, but so far only a few
specimens have been found. It forms greyish elliptical to cir-
cular spots, a quarter of an inch in diameter, on the leaves.
SPIR.ffiA, Spircea Ulmaricz.
Leaf Spot, Septoria Ulmarioe Oud. Rather injurious to the
foliage.
SQUASH, Cucurhita sps.
Anthracnose, Colletotrichum Lagenarium (Pass.) Ell. &
Hals. On ripe or stored squashes this is not uncommon,
and, possibly, it may also cause injury earlier in the season.
The depressed, rotten areas may attain considerable size, and
usually show the pinkish fruiting pustules. The fungus often
opens the way for a general rot by other fungi and bacteria.
See Watermelon.
Black Mold, Rhisopus nigricans Ehr. Plate XXVI, b.
This is a common mold on rotting fruit and vegetables. It
occurs, sometimes with the next fungus, on the fading flowers
of the summer squash, and in some cases is responsible for a
rot of the fruit. See Sweet Potato.
NOTES ON PARASITIC FUNGI. 359
Metallic Mold, Choanephora cucurbitarum (B. & R.)
Thaxt. Plate XXVI, c. Very often the black mold described
above occurs with this on the faded flowers, but the former
can be told with a lens by its shorter threads, bearing firmer,
spherical spore heads. This latter fungus is also easily dis-
tinguished by the metallic luster of the threads and the more
loosely compacted heads. It, no doubt, often blasts the blossoms
and may rot the young fruit also.
Powdery Mildew, Erysiphe cichoracearum DC. Conidia
only. See Pumpkin.
Wilt, Bacillus tracheiphilus Sm. Plate XXVI, a. In this
disease, bacteria clog the ducts of the stem or leaf petioles, so
that the water supply is largely cut off from the parts beyond, and
these wilt and eventually die. Cutting across the stems, one can
often squeeze out these organisms in a slight, viscid, milky
exudation. Apparently, insects distribute these germs and per-
haps produce the disease through punctures in the leaves or by
eating holes in them. Very often, diseased leaves are found
where the trouble has run down the petiole and in some cases
extended into the stem. The tissues of the leaf are more likely
to show a diseased condition than are the vascular bundles
in the stem. Spraying does not seem to lessen this trouble.
The wilted vines should be removed and care taken to keep
down the insects. Summer and Hubbard squash, also musk
melons and cucumbers, are subjected to this wilt, which last
year was more common than usual.
STKAWBERRY, Fragaria sps.
Fruit Rot, Botrytis vulgaris Fr. When the writer first
came to the Station in July, 1902, he found some strawberries
that had recently been sent in for examination, because they
were rotting badly on the vines. The common grey mold
was abundant on these and has since been seen occasionally in
the field. Last year some growers complained of a rot trouble
of the ripening fruit, which was probably caused by this fungus.
Apparently, the crop often suffers during wet weather at harvest
time from this rot. When it is likely to prove serious, the
24
360 CONNECTICUX. EXPERIMENT STATION REPORT, I903.
writer should judge that it could be minimized by carefully
gathering the rotten fruit at each picking.
Leaf Blotch, Ascochyta Fragarice Sacc. This is not so com-
n:on, and consequently not so injurious as the next trouble,
though occasionally it is found doing considerable damage.
The two are very similar in appearance, but with this one the
purplish blotches are larger, often merged, producing a general
browning of the margins of the leaves.
Leaf Spot, Sphczrella Fragarice (Tul.) Sacc. Plate XXV, d.
The spots on the leaflets are usually distinct, circular, and
possess a prominent purple border and a whitish center. The
imperfect or summer stage is parasitic, while the winter or asco-
spore stage develops on the old dead leaves. The destruction
of these leaves is therefore helpful in keeping the trouble in
check. Some growers mulch the beds with salt hay and then
burn them over in the spring, thus destroying the old leaves.
Others advocate the very frequent renewal of the beds, as the
trouble becomes worst in old beds. Spraying with Bordeaux
has also been found useful. One treatment is given before
blossoming, another after most of the petals fall, and a third
and perhaps fourth after the picking season.
Frosty Spots. Last fall some of the growers near New
Haven complained of a new leaf trouble that resembled mildew.
An examination of the leaves, however, showed that the whitish
spots were not due to any fungus but resulted from the flak-
ing away of the cuticle. Later, the whitish appearance gave
place to dead brown- spots. Evidently, the trouble was a
physiological one that had resulted in the flaking up of the
cuticle and the collapse of the epidermal cells. This was,
apparently, not due to frost, since it appeared chiefly before
the first frosts. It was worst on plants set out between rows
of early potatoes, and probably this treatment, with the unusually
moist season, prevented the proper transpiration of water, which
produced the injury through rupture of the cells.
SUNFLOWER, Helianthus annuus.
Leaf Spot, Septoria Helianthi Ell. & Kell. Produces sub-
circular or irregular brownish spots from which the tissue
sometimes drops out.
NOTES ON PARASITIC FUNGI. 361
RusT_, Puccinia Helianthi Schw. The uredo- and teleuto-
spores break out on either side of the leaves^ but more abun-
dantly below, in numerous reddish dusty pustules, about the
size of a pencil point.
SWEET POTATO, Ipomoea Batatas.
Black Mold^ Rhisopiis nigricans Ehrb- This produces a
soft rot of the roots. The grocer and the housewife very often
find it difficult to keep potatoes because of its attacks. Where
the skin is broken, the fungus develops its fruiting stage as
a dense growth of blackish threads, ending in the small spore
capsules.
SWEET VERNAL GRASS, Anthoxanthum odoratum.
Smut^ Tilletia Anthoxanthi Blytt. This changes the seed
into an inconspicuous smutted body. The smutted spikes are
about like the healthy in appearance, so the fungus is easily
overlooked. The only time it has been collected in the United
States was by the writer near New Haven in July, 1902.
SYCAMORE, Platanus occidentalis.
Anthracnose, Gla;osporium nervisequum (Fckl.) Sacc.
The leaves with this trouble develop brown, dead areas of
varying shape and size, 6ften running along the ribs. The
disease may become so serious that defoliation takes place.
The young branches, also, are said to be attacked. It is one of
the worst troubles of the sycamore in this state.
TEOSINTE, Euchlcena luxurians.
Smut, Ustilago Ze<2 (Beckm.) Ung. See Corn.
TIMOTHY, Phleum pratense.
Ergot, Claviceps sp. Small slender sclerotia are occasionally
found in the spikes.
Smut, Ustilago striceformis (West.) Niessl. On leaves.
See Red Top.
362 CONNECTICUT EXPERIMENT STATION REPORT, I903.
TOADFLAX, Linaria vulgaris.
White Smut, Entyloma Linarice Schrt. The fungus pro-
duces small, whitish, circular areas on the leaves and stem in
which the spores are permanently embedded.
TOBACCO, Nicotiana Tabacum.
Frost Fungus, Botryosporium pulchruni Cda. (Bofrytis lon-
gibrachiaia) . According to Sturgis, this fungus sometimes pro-
duces a stem rot in the tobacco while hanging in the barns
during the later stages of curing. He says : "Stems affected
with this disease are covered with pure white patches having
the appearance of a long pile velvet. These patches spread
rapidly, encroaching upon the veins of the leaf and destroying
the tissue and in the end inducing a more or less widespread
decay, especially in the neighborhood of the midrib and veins.
It is not unusual upon entering a barn, even during the process
of curing, to find the floor partially covered with the refuse of
the previous year's crop, the latter often looking as though a
fall of snow had whitened it, so densely is it covered with the
mycelium and spores of this fungus. The slightest current of
air serves to separate the spores from their attachment and
carry them through the barn, some finding lodgment upon and
at once infecting the curing stems and leaves." This fungus is
common in greenhouses upon decaying stems, especially tobacco
stems, left on the moist earth. Under certain conditions it may
act as a parasite. See Vinca. [Reps. 1891, p. 184; 1893,
p. 84.]
Seed Bed Rot {Fungus). The young tobacco plants some-
times dampen off in the seed bed apparently through the action
of some fungus. This trouble has not been thoroughly studied
yet. Care in the kind of soil used and in the regulation of
temperature and moisture in the beds, should help to check a
trouble of this kind.
Pole Burn {Fungi and Bacteria) . Sturgis also made a special
study of this trouble, which sometimes seriously affects tobacco
while drying in the barns, especially when the weather is moist
and warm and the barns can not be ventilated properly. He
says of it: "At first the disease is limited to the neighborhood
NOTES ON PARASITIC FUNGI, 363
of the veins and midrib of the leaf where moisture is super-
abundant, but its spread is very rapid, the small blackened areas
increase in size, become confluent and sometimes within thirty-
six, or at most forty-eight hours, not only is the whole leaf
affected but the entire contents of the curing barn may be
rendered quite worthless as tobacco. Examination shows that
the leaves have changed from greenish yellow to a dark brown
or almost black color, that the fine texture has disappeared, and
that instead of being tough and elastic, the whole leaf is wet
and soggy, and tears almost with a touch, falling of its own
weight from the stalk." Sturgis found this rotting was due
to various bacteria and fungi. Regarding prevention, he states :
"We have seen that whatever is the primary cause of pole burn,
its ill effects can be in a large measure, if not entirely, prevented
by a proper regulation of moisture and temperature." [Reps.
1891, p. 168; 1899, p. 265.]
Calico or Mosaic Disease. This is a trouble met in the grow-
ing fields of tobacco. The affected plants are ususLlly somewhat
stunted in growth, and the leaves have a pale greenish or later
a peculiar yellow mottling, due to changes in the chlorophyll
of the tissues. Usually these yellow streaks or areas follow the
bundles and are separated by the normal green tissue. The
trouble eventually renders the plants of little commercial value.
Most growers pull up the diseased plants as they find them in
the field, for their presence in the cured crop would only
detract from its value. The trouble is considered a physio-
logical one, rather than due to fungi or bacteria, and in nature
approaches the yellows of peach. Certain unfavorable condi-
tions in setting the plants or of the soil or moisture conditions
are said to produce the trouble. As yet, however, too little is
known of all the circumstances that contribute to this trouble
and how to avoid it. [Reps. 1898, p. 242; 1899, p.. 252.]
Rust. The cause of the irregular, usually small, spots appear-
ing on the leaves in the field and called "rust" by the growers,
is not known. Possibly it is also a physiological trouble.
[Rep. 1899, p. 255.]
Spot. The writer has found in tobacco grown under cloth,
circular, brown spots, about one-quarter of an inch in diameter,
on the leaves. These were not uncommon in one field and had
364 CONNECTICUT EXPERIMENT STATION REPORT^ 1903-
the appearance of the spot produced by the Alternaria fungus
on potato, etc. They showed the usual faint concentric rings
of development, but no signs of any fungus were discovered.
This is probably the same thing described by Sturgis, Rep. 1898,
p. 254, on tobacco grown in the open. He assigned no cause.
Its presence, in moderate amount, is not generally regarded
as a damage to the crop.
TOMATO, Lycopersiciim esculentum.
Anthracnose, Colletotrichum phomoides (Sacc.) Chest.
Plate XXVIII, b. This was found in a few fields on the ripen-
ing fruit, producing conspicuous sunken areas, in the center of
which numerous closely clustered spore pustules occurred. Evi-
dently it is a trouble that some seasons may produce serious
injury at the ripening period.
Blight^ Bacillus Solanacearum Sm. Plate XXVII, a-c.
The southern tomato blight was found, apparently for the first
time, in the vicinity of New Haven last season. While noticed
in several fields, it was only in the field of Mr. Andrew Ure,
described here, that it was found especially injurious. A gen-
eral view of the affected part of this field is shown in Plate
XXVII. It was peculiar in that four rows straight through
the field were very badly infected, many of the plants dying;
the bordering rows were less seriously affected, while the
remainder of the field away from these was practically free
from the disease. So far as could be learned, there was no
difference in the field or the treatment that could have produced
this. The only way the writer could explain it was that pos-
sibly a certain block of the plants in* one of the seed beds had
contracted the disease and had been set out together in the
field. Many of the plants had been killed before they showed
any considerable growth in the field. Others less seriously
infected were somewhat smaller than the healthy plants and
showed diseased leaves here and there. The leaves on any
part of the plant were affected, sometimes first turning yellow,
but usually soon dying outright. Very often the leaflets and
most of the petiole were brown and dead, while the lower part
of the petiole for an inch or two was still alive and green. Cut-
NOTES ON PARASITIC FUNGI. 365
ting across the green stems or petioles, the trouble showed as
diseased brownish spots, or as a complete ring in the bundles,
which are situated between the pith and the bark. In severe
cases there was also a lesion of the tissues in this vicinity. See
Plate XXVII, c. In very advanced stages the base of the stems
showed a general soft rot. Sometimes the leaves showed dead
areas around the bundles and examination of the ducts showed
these choked with bacteria. It was not determined if this was
caused by the same bacterial agents that produced disease in the
potatoes this same year ; there is a possibility that it was. The
potato bug and other insects probably carry this disease after
it gets started in a field. It should be noted in this case,
however, that the disease, apparently, did not spread through
the field, neither were the potato bugs, etc., numerous last year.
Downy Mildew, Phytophthora infesfans DeBy. Thaxter
collected this fungus on the tomato where it was doing damage ;
but apparently, its occurrence on this host is comparatively rare.
See Potato. [Reps. 1890, p. 95 ; 1893, p. 103.]
Fruit Mold, Macrosporium Tomato Cke. Very commonly,
this forms a dense, olive-black, moldy growth on the point rot
of the fruit and formerly was thought to be the cause of this
trouble, but now it is considered only a saprophyte. See Point
Rot.
Leaf Mold, AUernaria Solani (E. & M.) J. & G. Occurs not
uncommonly on the leaves, occasionally doing damage. Often
it is associated with the next trouble and may be mistaken for
it. See Early Blight of Potato.
Leaf Spot, Septoria Lycopersici Speg. This is one of the
most serious troubles of the tomato and has come into promi-
nence during recent years. The leaves, stem and, rarely, the
green fruit, may be attacked. The trouble is most injurious
to the leaves, which become thickly covered with small, angular
spots, usually having a greyish center and a deeper colored
border. Apparently, it rarely matures on the small black specks
it may produce on the fruit. Very probably it passes the
winter through the summer spores formed in the fruiting
receptacles on the stems, since no winter spore stage has been
associated as yet with it. The trouble may be prevented largely
by spraying with Bordeaux. The first spraying should be
given a couple of weeks after transplanting, and two or three
366 CONNECTICUT EXPERIMENT STATION REPORT, I903.
additional sprayings should follow each other at intervals of
about three weeks. [Bull. 142, p. 18.]
Scab, Cladosporium fulvum Cke. This fungus forms dense
olive-brown growths in areas of varying size, on the under
surface of the leaves, and often produces discoloration of the
tissues on the upper surface. It is a trouble that occurs both
in the field and greenhouse and sometimes does considerable
injury. Spraying with Bordeaux, if taken in time, will pre-
vent it. In the greenhouse care should be used in sprinkling
water on the foliage, and the vines should not be planted too
closely. [Reps. 1889, p. 173 ; 1890, p. 95 ; 1893, p. 102 ; Bulls.
Ill, p. 15; 115, p. 16.]
Sleeping Disease or Wilt, Fusarium Lycopersici Sacc. In
the Experiment Station greenhouse, for several years past, this
trouble has appeared with increasing severity. As the seed
has been selected each year from these plants, possibly this
explains in part the severity of the trouble. It does not usually
show until the plants have attained full size and are beginning
to blossom abundantly. At first, a lower leaf or two will wilt,
turn yellow and finally die. Gradually, the disease works up,
successive leaves dying and drying up on the vine. At the
time the plants come into bearing, the trouble usually shows
prominently. Cutting across the green stem or petioles at the
base of the plant, the disease first shows a discoloration in the
vicinity of the bundles. Very often three diseased spots show
in these cross sections. If the fibro-vascular bundles are exam-
ined in cross section under the microscope, they are found to
be more or less filled with the mycelium of the fungus. This
choking up of the vessels, with their later diseased condition,
prevents the proper amount of moisture being carried up the
plants, which in time suffer severely because of this. As the
leaves die, the fungus may work to the surface from the vicinity
of the petiole, producing dead areas on the stem which eventu-
ally show abundance of the whitish mycelium. The spores are
formed abundantly on this, and it then assumes a pinkish
color from their presence. Eventually, the whole plant dies
and dries up, the stem becoming more or less completely cov-
ered with the pinkish, moldy growth. Very often this pink
mold may show on the ripe fruit, especially at the base, develop-
NOTES ON PARASITIC FUNGI. 367
ing out on it from the petiole. The disease is unquestionably
carried in the soil and possibly also by the mycelium develop-
ing up the petioles into the seed. In cutting across green
fruit, one occasionally finds that the disease has penetrated
partially into it, and in this way may finally reach up into the
seed. Where the trouble is established in a greenhouse, sterili-
zation of the soil and treatment of the seed with hot water will
apparently stop the trouble, if done thoroughly. Perhaps it
would be best merely to sterilize the soil and get seed from
an uninfected source.
Point Rot. Plate XXA/"!!!, a. Apparently, the point rots of
the greenhouse and the field are the same trouble. It usually
first shows on the green fruit as a sunken, brown, rotted spot
at the blossom end. This gradually enlarges, and later often
becomes more or less covered with mold, especially the black
mold. As yet, the cause of point rot is not surely known — it
may be a. bacterial trouble or it may be a physiological one.
Selby, of Ohio, states that sub-irrigation in the- greenhouse
will largely prevent it. Spraying has not given very encour-
aging results.
TULIP TREE, Liriodendron Tulipifera.
Powdery Mildew, Erysiphe Liriodendri Schw. Forms a
rather inconspicuous cobweb-like growth on the leaves. The
asco-spore stage is not produced very abundantly.
TURNIP, Brassica sps.
Club Root, Plasmodiophora Brassicce Wor. See Cabbage.
Downy Mildew, Peronospora parasitica (Pers.) Tul. Plate
XXVIII, c. The fungus forms whitish tufts of the summer
spore stage in patches on the lower surface of the leaves and
produces discoloration of the tissues above. It occurs rather
commonly in the fall in turnip (Brassica Rapa) fields and has
also been found on the radish.
Powdery Mildew, Erysiphe Polygoni DC. The conidial
stage only occurs on the upper surface of the leaves (Brassica
campestris) , producing the usual whitish powdery growth.
368 CONNECTICUT EXPERIMENT STATION REPORT, I903.
Scab, Oospora scabies Thaxt. Observed by Sturgis on
roots of both Brassica campestris and B. Rapa. See Potato.
[Reps. 1894, p. 126; 1896, p. 266.]
VINCA, Vinca 7iiajor.
Frost Fungus, Botryosporinm pulchruin Cda. Ordinarily
this fungus occurs as a saprophyte on dead stems lying on the
moist ground, but on the Vinca it acted as a parasite. However,
the varigated vinca plants were in pots placed temporarily under
the greenhouse benches, where the water dropped down from
above, so the conditions were favorable for the fungus, but
not for the plants. The plants became so abundantly infested
with the fungus that they were all killed. The luxuriant, white
growth resembles somewhat the very heavy hoar frost that
sometimes covers sticks on the ground. Examining it carefully
with a hand lens, the erect threads, about one-quarter of an inch
high, are seen to be provided with diverging side branches upon
which are clustered the spores, the whole having a feathery
aspect. See Tobacco.
VIOLET, Viola odorata.
Anthracnose, CoUetotrichum ViolcB-tricoloris Sm. Occurs
occasionally on the leaves.
Leaf Blight, Cercospora Violce Sacc. Apparently occurs
only occasionally, the spot disease being the common trouble.
Leaf Spot, Phyllosticta Violce Desm. Another occasional
trouble. [Rep. 1891, p. 166.] These three leaf fungi are very
similar in appearance, producing whitish or greyish spots.
Root Rot, Thielavia basicola Zopf. Reported by Thaxter in
Rep. 1 89 1, p. 166.
Spot Disease, /^/^^rnana Violce Gall. & Dor. Plate XXVIII, d.
This seems to be the chief trouble with greenhouse violets in
this state. The white spots are circular, usually about one-
eighth of an inch in diameter. They seem to start as black
specks ; and on the stem this blackening is most pronounced.
It is only rarely that the writer has found the Alternaria pro-
ducing spores on these spots, which seems strange since the
disease often spreads rapidly in the beds. The trouble is likely
NOTES ON PARASITIC FUNGI. 369
to get started in the houses in the fall before heat is turned
on, especially if the grower is trying to cut down his coal bill.
The character of the house, as to moisture, soil, etc., probably
also plays a prominent part in the trouble. The disease is
very often worst where violets have been grown for some time.
Growers generally pick off the, diseased leaves as soon as they
appear; in bad cases, however, this often means very severe
pruning. Possibly the thorough removal of all diseased leaves
when the plants are set out, followed with a treatment with
Bordeaux mixture, might prove helpful in preventing the trouble.
After the disease is thoroughly started, perhaps little can be
expected from spraying. [Bull. 142, p. 18.]
VIRGINIA CREEPER, Ampelopsis quinquefolia.
Leaf Spot, Phyllosticta Labruscce Thm. On the leaves only.
See Grape.
Powdery Mildew, Uncinula necator (Schw.) Burr. See
Grape.
WALNUT, Juglans nigra.
Anthracnose, Marsonia Juglandis (Lib.) Sacc. Produces
subcircular, usually dark reddish brown, spots or blotches on the
leaves.
WATERCRESS, Nasturtium officinale.
Leaf Spot, Cercospora Nasturtii Pass, Produces roundish
light colored spots on the foliage, thus rendering it inferior for
decorative purposes.
WATERMELON, Citrulhis vulgaris.
Anthracnose, Collet otrichum Lagenarium (Pass.) Ell. &
Hals. Plate XXVIII, e. This fungus occurs on both the fruit
and the leaves. On the former it produces sunken, rotted areas,
at first small, but increasing in size and number, usually until
the melon is worthless. On these areas, the spores ooze out in
viscid, pinkish masses ; sometimes they may germinate in posi-
tion, giving rise to a superficial growth of white mycelium, as
370 CONNECTICUT EXPERIMENT STATION REPORT, I903.
shown in the plate. Either green or ripe fruit may be attacked.
On the leaves, the fungus causes dead brown areas, upon which
the exudation of spores may not be very conspicuous. This
same fungus occurs on cucumbers, musk melons and squash.
In the fall, the old vines and rotted fruit should be gathered
from the field and burned, as they help to carry the trouble in
the soil. Spraying with Bordeaux should begin when the vines
start to run, and these should be kept covered during the season.
[Bull. 142, p. 7.]
Downy Mildew, Plasmopara Cuhensis (B. & C.) Humph.
So far as observed, this has not proved serious on this host.
The fruiting threads are produced so meagerly on the under
surface, that usually they can not be detected by a hand lens.
See Musk Melon.
Leaf Mold, Alternaria Brassier var. nigrescens Pegl. See
Musk Melon.
PLATE IX.
a. Young tree with injured bark at base dropping its leaves in July, p. 30;
b. Injured bark studded with
fungous growth. X 2.
c. Health)' bark showing lenticels.
WINTER INJURY TO BARK OF APPLE.
PLATE X.
a. Peach, p. 341.
Healthy.
Injured.
Healthy,
b. Apple, p. 303.
c. Plum, p. 345.
Injured. Health3^ Injured.
WINTER INJURY TO WOOD OF FRUIT TREES,
Healthy,
PLATE XI.
a. Black Rot, p. 298.
b. Sooty Blotch, p. 302.
X 3
X 2
c. Cluster Cup of Rust, p. 301. d. Fly Speck, p. 299.
FUNGI OF THE APPLE.
I
PLATE XII.
a. On fruit.
Scab, p. 301.
X2.
b. On twig.
c. Bitter Rot, p. 297. d. European Canker, p. 299.
FUNGI OF THE APPLE.
PLATE XIII.
Barley.
Bean.
a. Smut, p. 306.
b. Downy Mildew, p. 307. c. Anthracnose, p. 307.
Bean.
X 2.
d. liliiJclit, p. 307. c. Rust, p. 30S.
FUNGI OF BARLEY AND BEAN,
PLATE XIV.
Blackberrv.
Beet -h }
a. Leaf Spot, p. 309.
BlackberrJ^
b. Leaf Spot, p. 309.
Buckwheat.
c. Rust, p. 309. d- Leaf Blight, p. 310.
FUNGI OF BEET, BLACKBERRY, BUCKWHEAT.
Cabbage.
PLATE XV.
Carnation.
a. Club Root, p. 310.
Cherr}^ X 2.
I|r.^:^
ii^aw
b. Rust, p. 312.
Chr3'santhemum X 2.
c. Powder Mildew, p. 314. d. Rust, p. 315.
FUNGI OF CABBAGE, CARNATION, CHERRY, CHRYSANTHEMUM.
PLATE XVI.
Corn. -^ )A.
Clover.
a. Rust, p. 316.
Currant. X 3-
b. Smut, p, 317.
Elm Bark. X 2.
c. Red Knot, p. 319. d. White Fungus on Elm-Leaf beetle, p. 321.
FUNGI OF CLOVER, CORN, CURRANT, ELM BEETLE.
PLATE XVII.
Grape.
a. Black Rot, p. 323.
Hazel X 2
Hollyhock X 2.
b. Downy Mildew, p. 324.
Horseradish.
c. Black Knot, p. 325. d. Rust, p. 326. e. Leaf Spot, p. 327.
FUNGI OF GRAPE, HAZEL, HOLLYHOCK. HORSERADISH.
PLATE XVIII.
a. Blighted vine in the field.
b. Under surface of leaf showing dead areas.
BLIGHT OR DOWNY MILDEW OF MUSKMELON, p. 330.
Iris.
a. Rootstock Rot, p. 327.
Oats.
PLATE XIX.
Musk Melon.
b. Scab, p. 331.
X2 On leaf.
1 ■,'i'itM
c. Black Rust, p. "332.
d. Crown Rust, p. 333. c. Smut, p. 32
FUNGI OF IRIS, MELON, OATS.
PLATE XX.
a. Black Spot, p. 333.
Stem Rot, p. 334.
b. End view. c. Cross-section.
FUNGI OF ONION.
PLATE XXL
b. Brown Rot, p. 337.
a. On fruit.
Scab, p. 340.
c. On twigs. X 2.
d. On leal. x
FUNGI OF PEACH,
PLATE XXII.
a. Bacterial Rot, p. 350.
b. Dry End Rot, p. 349.
c. Scab, p. 350. d. Blight, p. 347.
FUNGI OF POTATO.
PLATE XXIII.
a. Green leaves showing early stage of blight, p. 347.
b. Todd's blighted field, photographed July 28, 1902 ; less than a week before,
this field was perfectly green.
BLIGHT OF POTATO.
PLATE XXIV.
Phlox.
Plum.
a. Powder)' Mildew, p. 345.
Plum.
Raspberry.
b. Crown Gall, p. 346.
X 2
" ,^|^j:
. ■■■ :M
c. Black Knot, p. 345. d. Crown Gall, p. 354. e. Cane HIight, p. 35;
FUNGI OF PHLOX, PLUM, RASPBERRY,
a. Powder_y Mildew, p. 356.
Rose.
b. Ergot, p. 357.
Strawberry.
c. Leaf Blotch, p. 355. d. Leaf Spot, p. 360.
FUNGI OF ROSE, RYE, STRAWBERRY,
a. Bacterial Wilt, p. 359.
b. Black Mold at base of blossom, p. 358.
c. Metallic Mold on blossom, p. 359. X
FUNGI OF SQUASH.
PLATE XXVII.
a. Showing area in A. Urc's loiiiaio tiekl where blight killed man)' plants.
Blighted. Healthy,
b. Tomato leaves.
i #
1 1 • •
c. Cross and longitudinal sec-
tions of tomato stems. Upper three
rows blighted ; lower two rows
healthy stems.
BACTERIAL BLIGHT OF TOMATO, p. 304.
PLATE XXVIII.
Tomato.
a. Point-Rot, p. 367-
Turnip, X 2
b. Anthracnose, p. 364.
Violet.
c. Downy Mildew, p. 367. d. Spot Disease, p. 368.
Youno- Watermelon.
e. Anthracnose, ]>. 3()<).
FUNGI OF TOMATO, TURNIP, VIOLET, WATERMELON.
JDfrllBjRARY of tl
Agricultijtr '
Colle
State of Connecticut
REPORT
OF
The' Connecticut Agricultural
Experiment Station
FOR THE YEAR 1904
PART IV.
REPORT OF THE STATION BOTANIST
CONNECTICUT
AGRICULTURAL EXPERIMENT
STATION
REPORT OF THE BOTANIST
G, P. CLINTON, Sc. D.
I. Notes on Fungous Diseases, etc., for 1904.
II. Down}^ Mildew, or Blight, Peronoplasmopora Ctihensis (B. & C.) Clint.,
of INIusk Melons and Cucumbers.
III. Down}^ Mildew, or "QW'^'i, Phytophihora infestans {^o'!\X.)V)&^y., of
Potato.
Issued May, 1905
NOTES ON FUNGOUS DISEASES FOR I9O4. 3II
REPORT OF THE BOTANIST.
NOTES ON FUNGOUS DISEASES, ETC., FOR 1904.
In the last Annual Report, 1903, pp. 279-370, the writer gave
short notes on all of the fungous and bacterial diseases and
physiological troubles which had been observed up to that time
on the cultivated plants of Connecticut. In the present article
are given notes on those that were prominent the past year and
those that were much less conspicuous than during the two
previous seasons, together with brief descriptions of the few
troubles found in the state for the first time and additional
information gained concerning old ones. The half-tone illus-
trations are natural size unless otherwise stated. On the whole,
1904 was not conspicuous for serious outbreaks of fungous
troubles, especially when compared with the two previous years.
This was largely due to the warmer, drier season.
ALFALFA, Medicago sativa.
Leaf Spot, Pseiidopeziza Medicaginis (Lib.) Sacc. Plate
XVIII, a. Recently further attention has been called to the cul-
tivation of alfalfa in this state for dairy purposes. While
undoubtedly a valuable plant in many regions, most efforts to
raise it here have been unsuccessful thus far. In the Report
for 1903, p. 297, attention was called to the leaf spot disease
of this plant. During the past season this disease considerably
damaged a small plot of alfalfa grown on the Experiment Sta-
tion grounds. Plate XVIII, a, shows the general appearance of
the purplish spots it produces on the leaves, which, as they
become badly infected, turn yellowish and die prematurely.
APPLE, Pirus Mains.
Powdery Mildew, Podosphaera leucotricha (Ell. & Ev.)
Salm. Plate XVIII, b. As noted in the Report for 1903, p.
300, this fungus does most damage to nursery stock, occurring
commonly on the twigs. It is worse on some varieties than on
others and was found especially abundant on Rome Beauty in
one nursery the past season. The illustration shows the minute
312 CONNECTICUT EXPERIMENT STATION REPORT, I904.
perithecia crowded together in dark patches on the dirty white
mycehum that enveloped the twigs of that variety.
RusT^ Gymnosporangium macropus Lk, Plate XVIII, c.
Apple rust was not as prominent as usual the past year. Cer-
tain varieties are known to be very susceptible to attack. (See
Report 1903, p. 301.) This was shown very plainly last spring
in the Experiment Station disease garden in the case of Bechtel's
Flowering Crab. A ripe "cedar ball" of the above rust was
attached to the top of a young tree during moist weather in May.
In June the spermagonial stage was very prominent on the upper
side of many of the leaves to which had been carried the germi-
nating sporidia from this cedar ball. The illustration shows
the clusters of spermagonia on a leaf which developed about
forty separate points of infection. On another leaf over one
hundred distinct spermagonial clusters were counted, while on
some of the leaves the whole surface was covered, so that there
was no separation into distinct colonies. In July the aecidial
stag'e became prominent on the under surface of these leaves.
Scab, Venturia incequalis (Cke.) Aderh. This fungus was
not unusually prominent the past season. Attention was called
in the last Report, p. 301, to a case where the parasitic stage,
F itsicladiufvi dendriticum, was found on' the twigs of a single
nursery tree. Last fall it was found again in another nursery
on the twigs of the Fall Pippin and the leaves of this variety
were unusually scabby. No sign of the asco-spore stage has yet
been observed on the twigs.
Winter Injury.. Mention was made in the Report for 1903 of
the injury done by the two unusual winters of 1902-3 and
1903-4. During the past summer further observations have
shown a number of young orchards that suffered severely from
winter injury. Its effect on young orchard and- nursery trees
was usually shown by the killing or severe injury of the wood.
If snow was on the ground this injury only extended down to
the snow line. Externally the trees looked all right, as the
bark and cambium were not injured, so that new wood was
formed during the summer, but this annual ring of growth was
often very slight. A cross section of the stem showed this as
a white growth just beneath the bark and around the blackened
injured wood of the preceding seasons. Some trees were killed
outright or so severety injured that they died during the sum-
NOTES ON FUNGOUS DISEASES FOR I904. 313
mer. When the injury did not extend entirely down to the
stock, badly damaged trees were cut off and a new trunk started
from a bud on the uninjured part of the scion. Such trees, if
properly cultivated, made very satisfactory growth during the
summer. Where the injury was not so severe, thorough
pruning proved helpful.
In bearing orchards the injury usually showed itself in the
bark and not in the wood. Usually the bark was injured
only at the base of the trunk by a girdled, dead area extend-
ing from the ground up, often only on one side. Sometimes
isolated dead areas could be found further up on the trunk
or on the branches. The younger trees suffered more severely
and often in the summer shed many of their leaves, and if
the trunk was completely girdled finally died. When the bark
becomes loosened on these dead areas it should be scraped
off and the wood painted over to prevent rot. For orchard
sites high, exposed hillsides are preferable, other things being
equal, to sheltered lowlands, where, in our experience, winter
injury most commonly occurs. Late cultivation and exces-
sive fertilization, too, are apt to send the trees into winter
with their wood in an unripened condition and thus more sus-
ceptible to injury. Some of the nurseries of the state suffered
severely from winter injury to stock left outdoors. To prevent
future trouble from this source one firm the past summer built
a large storage house where all of the stock offered for sale in
the spring can be wintered out of reach of the cold. See Peach.
ASPAEAGTIS, Asparagus officinalis.
Rust, Puccinia Asparagi DC. Plate XIX, a-c. This fungus
has been mentioned before as doing damage in this state, having
been reported first in 1896. So far, however, the aecidial stage
(see Report 1903, p. 305) has not been reported. This was
observed the past season in a certain bed in Westville. The
bright orange spores of this stage are produced in minute, toothed
cups, embedded usually in elliptical clusters on the stems. (See
Plate XIX, b.) Compared with the red and black rust stages
of this fungus, this stage is infrequent and .harmless (except
as it serves as the source of infection for these other stages) and
appears only in the spring and early summer. In most of the
314 CONNECTICUT EXPERIMENT STATION REPORT, I904.
plants examined it was confined to the lower twelve inches of
the stem. In this particular field the asparagus had been
gathered by snapping off the tender tips, thereby often leaving
stubs several inches long. It was on these old stubs that most
of the aecidia were found. This method of removal hence
served as a means of increasing the rust in the field, for if the
asparagus had been cut off close to the ground the rust would
have developed only on a few of the old plants. The reason
why the aecidial stage usually appears on the base of the plants
is apparently because infection takes place from the black rust
stage carried over winter in fragments of the old stems in the
ground and the bases of the stems are the most favorably
situated portion of the plant for infection.
As the aecidial stage was just appearing in this field and as
there were few old plants, the field having been severely cropped,
it was decided to see if the subsequent injurious stages of the
rust could be kept out of the field by thorough removal of stubs
and stems showing the aecidial stage, since the bed was some-
what isolated. The aecidial stage was first observed June 14,
but many of the aecidial cups were unopened and the weather
was not favorable for the spread of the rust from the mature
ones. June 15 to 17 the writer went carefully over the field,
about a quarter of an acre, and removed all of the parts show-
ing rust. The field was gone over twice at this time, as it was
discovered that on the first search not all of the rust was found.
In all 858 rusted stubs (chiefly) and stems were removed.
There was no sign whatever of either the red or black rust stage
at this time. On June 27 the field was again examined and 38
stems and stubs were removed. Of these, however, 11 showed
the red rust (uredo) stage, though not abundantly. (See Plate
XIX, c.) These were chiefly on the lower parts of the plants
and were just beginning to split open to shed their spores. They
were also mostly confined to plants showing the aecidial stage.
The field was examined a third time on July 11 and 192 stems
were removed. As many of these were large plants, further
removal was impossible without injury to the bed. Then, too,
the uredo stage had become quite common at this date and a few
teleuto sori (black rust) were also present. Lest than half the
stems removed showed the aecidial stage. It is quite probable
that not all of the plants showing the uredo stage were cut at
NOTES ON FUNGOUS DISEASES FOR I904. 315
this time, as in large plants the scattered outbreaks were easily
overlooked. August 4 the field was examined again and the
uredo stage was found rather common through it. About Sep-
tember 23 the field was mowed and the tops raked together, —
not very carefully, — and burned. The field was not examined
until after this was done, so the relative amount of rust present
at this time was not determined. It is easily seen from what
has been stated that this removal of the aecidial stage did not
prevent the uredo stage at least from becoming fairly abundant
in the field. What effect this removal, coupled with the burn-
ing of the canes in the fall, will have, remains to be seen another
year. That the very careful removal and burning of all of the
tops and litter in the fall for several years helps to decrease
the rust, if the patch is isolated, has been shown, apparently, in
a small bed at the Experiment Station. In 1896 Dr. Sturgis
first observed the rust in this bed. Beginning about 1897, and
for at least four years, the tops and litter from this bed were
removed and burned. The rust has gradually become less, until
last season none whatever was found in it.
Rust Parasite, Darluca Fihmi (Biv.) Cast. Plate XIX, d.
This fungus is parasitic on the rust fungus, and so is bene-
ficial in checking the latter. It was very abundant in the
field described above. Unquestionably it prevented many of the
aecidial ciips from maturing their spores. The fruiting recep-
tacles of this fungus appear in the illustration as minute black
dots covering the area infested by the rust. The same fungus
also is common here on the uredo and teleuto stages of the
asparagus rust. In one field observed the past year that had
been killed, apparently, by the rust, this parasite was much more
conspicuous than the rust itself. Probably in this case the fun-
gus was parasitic on the hidden mycelium of the rust and largely
prevented its spore formation, so that the parasite, rather than
the rust, appeared to be doing the harm. It is barely possible,
however, that to some degree the parasite was really intruding
on the host without the aid of the rust and so was responsible
for part of the injury. This same parasite occurs on a number
of other rust species in this state ; for example, carnation rust
and blue-grass rust.
3l6 CONNECTICUT EXPERIMENT STATION REPORT, I9O4.
BEANS (LIMA), PJias coins lunatus.
Bacterial Spot. Plate XX, a. The cotyledons of the lima
bean at the time the seedlings appear above ground often show
purplish discolored areas that develop into sunken spots, as is
shown in the illustration. Microscopical examination of these
in their young state generally reveals bacteria present before
the fungi which later often fruit at these places ; while without
positive evidence, these cankered areas seem to be one of the
sources of infection of the bacterial disease which later in the
season often appears on the leaves as reddish bordered spots
(Report 1903, p. 307) and does considerable injury.
CABBAGE, Brassica oleracea.
Downy Mildew^ Peronospora parasitica (Pers.) Tul. This
fungus has been reported before on other cruciferous plants,
but was observed for the first time last spring on young cabbage
plants grown in a hot-bed. The trouble did not continue after
the plants were set in the field, and, no doubt, was induced by
too moist and crowded condition of the plants in the bed.
CHEEEY, Primus avium.
Brown Rot^ Sclerotinia fructigena (Pers.) Schrot. Plate
XX, b. A specimen of Governor Wood cherry in the Experi-
ment Station grounds seems to be especially subject to this rot
year after year. In 1904 the disease showed very early on
the perfectly green fruit. An examination indicated that
the curculio or other puncturing insects had considerable to do
with spreading it, as often the infected fruit showed signs of a
sting and the trouble was almost as bad while the fruit was green
as it was later when the fruit was ripe and more easily infected.
Some of the blossoms were also infected, but no diseased twigs
were found, though careful search was not made for them. The
tree had been sprayed during the winter with lime and sulphur,
which still covered it rather thoroughly, but this apparently had
no influence in keeping down the rot, as one might suppose it
would if it started first from spores produced on the twigs. A
careful search has been made for three years for the Sclerotinia
stage en the old cherry pits lying on the ground, but this has
never been found. Very few mummies remain hanging on the
NOTES ON FUNGOUS DISEASES FOR I904. 31/
tree at the beginning of spring, though their pedicles more often
remain attached. The illustration shows that the disease often
kills these pedicles, sometimes producing spores on their upper
end. It was thought that possibly the fungus was perpetuated
by its mycelium passing down the diseased pedicles into the
fruiting spurs and then up into the flowers in which it was found
in the spring. Examination of the fruiting spurs in the winter
showed that often those having the old pedicles attached were
dead, while cross sections of others revealed reddish discolora-
tion of the tissues. Rough microscopic sections of these showed
that often many of the parenchyma cells of the bark and pith
were dead or severely injured, but there was no evident indi-
cation of mycelium, and when diseased or dead spurs were
placed in a moist chamber or diseased tissue from them was
inserted in Petrie dishes of agar agar no development what-
soever of the Monilia fungus took place. On the other hand,
when the mummied fruit and diseased pedicles were placed in
the moist chamber the production of the Monilia spores was
abundant. These observations, then, indicate that the fungus
does not travel down the diseased pedicles and from these infest
the fruit spurs, but that the infection each spring comes, as
ordinarily supposed, either from the mummied fruit (and
pedicles) or infected branches, in which the Monilia spores are
again produced in early spring during moist weather, and from
these carry the disease first to the blossoms and from them to
the young fruit, their infection of the latter being largely aided
by puncturing insects. The influence of a puncture on the fruit
was shown with green cherries, kept in a moist chamber in the
laboratory, in which the spores of the fungus were inserted
through a needle puncture. These cherries started to rot imme-
diately at the punctured places, while others with spores placed
on them without puncture and checks with no spores placed
on them, though rotting later, usually started at some other
point than where the spores were placed, probably from some
injured place in the skin where spores had previously lodged.
CORN, Zea Mays.
Leaf Blight^ H elminthosporium turcicum Pass. This fun-
gus, which was so injurious in 1903, did practically no damage
the past season, thus showing that it is to be feared only in very
moist seasons when the corn naturally does poorly.
3l8 CONNECTICUT EXPERIMENT STATION REPORT, I9O4.
CUCUMBER, Cucumis sativus.
Downy Mildew, Plasmopara Cubensis (B. & C.) Humph.
Not injurious this season. See Musk Melon.
DEWBERRY, Ricbus Canadensis.
Orange Rust Parasite, Tuber ctdina persicina (Ditm.)
Sacc. Plate XXI, a. This fungus, especially in the west, is
a common parasite of various rusts. Here, on the orange rust,
it does not form the dusty purplish spores of the Hyphomycetous
stage so conspicuously as it does later the subspherical sterile
purplish sclerotia (See illustration.) There is little doubt that
if these were properly developed they would reveal the existence
of an asco-spore stage as yet unknown. It is questionable
whether the fungus is of any practical use here in keeping
the orange rust in check.
EGG PLANT, Soianum Melongena.
Wilt^ Fusarium sp. Plate XXI, b. The cause of this
trouble has not been determined definitely, though it is probably
a Fusarium fungus. It was present again the past year in some
of the fields of this plant. Infected plants showed a dwarfed,
yellowish appearance, and produced little and inferior fruit.
Late in the season an examination of the badly diseased plants
showed that the stem and roots under ground were badly rotted,
as shown in the illustration. As was expected, spraying pro-
duced no favorable results with this trouble. There is no
question that the disease begins in the very young plants, prob-
ably always in the seed bed, though it may not show plainly at
this time, and starts from infected soil or diseased seed. Care,
therefore, when possible, should be used to select the very best
seed from undiseased plants and to use fresh soil in the seed
beds.
EIG, Ficus Carica.
Smutty Mold, Sterigmatocystis Ficuum (Reich.) P. Henn.
Plate XXI, c. This smutty mold has been unusually common
the past season in the market figs. The spores of the fungus
partially fill the interior of the figs with a black smutty mass so
much like the true smuts that the fungus was originally
NOTES ON FUNGOUS DISEASES FOR I9O4. 319
described as one of these. It belongs, however, under the
Hyphomycetes, or imperfect fungi. The same or a similar
fungus also occurs in dates, but has not yet been reported in
this state, though probably not uncommon in the markets.
GRAPE, Vitis sps.
Powdery Mildew^ Uncinula necator (Schw.) Burr. Plate
XXII, a-c. The powdery mildew of grapes was unusually
abundant last fall, becoming especially prominent on the fruiting
stems and the berries. It did not seem to cause unusual injury,
however, except where it occurred on the thin-skinned varieties,
especially the white varieties, in which the berries were more or
less wiltedj besides being somewhat disfigured by the presence
of the fungus. The illustrations show the minute black peri-
thecia, or spore , receptacles, very abundantly scattered or clus-
tered in the superficial whitish mycelium that covers various
parts of the host. Suggestions for treatment were given in the
Report for 1903, p. 324.
MULBERRY, Morus sp.
Bacterial Disease, Bacillus Cuhonianus Macch. {Bacterium
Mori Boy. & Lamb.) Plate XXIII, a-b. This disease was
found in the state for the first time in one of the nurseries,
where it was causing more or less injury to the young trees.
Upon the leaves the disease shows as small reddish brown spots,
when moist often semi-pellucid, that penetrate through the
tissues to both surfaces. These are often more prominent and
numerous than is shown in the illustration. The chief injury
in this nursery, however, was to the twigs. Many of the
branches and even whole young trees had a stunted, yellowish
appearance. Usually the cause could be traced somewhere on
the stem to an evident canker, like those shown in the illustra-
tion, which more or less completely girdled the stem. As
these diseased areas in the bark become older, the growth of
the tissues often tends to cut them off from further develop-
ment, so that they show merely as a rough or corky superficial
spot in the bark. When the disease penetrates to the cambium,
however, the disease usually spreads internally between the bark
320 CONNECTICUT EXPERIMENT STATION REPORT, I904.
and wood, doing considerable injury to each; see cut end of
the largest branch in the illustration. This diseased condition,
then, may not show exteriorly except through the yellowish,
sickly growth. Sometimes the trouble becomes so bad that the
young stem can be easily snapped off at the diseased place.
This disease was first described from Italy and France and has
been observed by the writer in Illinois on both cultivated and
wild species of the mulberry. Probably the best treatment is
to thoroughly prune out the disease in winter time, as is done
for pear blight.
MUSK MELON, Cucumis Melo.
Bacterial Rot. Plate XXIII, c. A bacterial rot of the
fruit was not uncommon in some of the musk melon patches
the past summer. It seems to have been caused by the same
organism that produces the wilt of the vines, or at least this
may have been its starting point. The fruit developes a soft
internal rot, without external evidence in the youngest stages,
but eventuall}^ it spreads to the exterior, especially on the side
next the ground. Some melons were found in which the bac-
teria were limited to the bundles in the peduncle and to those
in the interior of the fruit, the surrounding tissues being healthy
as yet, thus suggesting its relationship to the bacterial wilt, which
was also found in these fields. Vines that were thoroughly
sprayed several times during the season developed the rot in
the fruit as badly as those not sprayed.
Downy Mildew (Blight), Plasmopara Cubensis (B. & C.)
Humph. This trouble, which has been so common and injurious
during several seasons past, was very uncommon the past year,
so far as the writer observed doing no damage whatever. In
1903 its diminishing injury and later appearance was reported
by the writer and the prediction made that it was on the wane.
In 1904 for the first time in several years a fair crop of musk
melons Avas obtained. This was largely due to the drier, warmer
summer, which, besides keeping this fungus in check, was
responsible for a vigorous growth of vines so necessary for the
production of fruit in this crop. (See special article on this
blight in the present Report.)
NOTES ON FUNGOUS DISEASES FOR I904. 321
ONION, Allium Cepa.
Stem Rot, Botrytis sp. Plate XXIV, a-b. The stem rot
trouble of the Southport White Globe onions (see Report, 1903,
p. 334), which was so bad the two previous years, did no damage
in 1904. As was suggested in the last Report, this trouble
is largely induced by unusually wet seasons, especially during
July and August. These months, in 1904, being considerably
drier than those of the two previous years, were thus unfavora-
ble for the development of the fungus. No signs of it whatever
was found on plants in the field and no especial complaint of the
rotting of the stored onions was made by the growers. Where
planted, this variety did fairly well last season, except for the
injury of the onion maggot, which was unusually common on
all onions. Many growers, however, were so disheartened by
the losses of the previous seasons that the acreage devoted to
this variety was very much smaller than usual. So far, the
writer has been unable to find any Sclerotinia stage connected
with this fungus. The selerotia which often develop in the
rotting tubers and carry the fungus over the winter apparently
develop only the Botrytis stage, v/hich causes the injury in the
field and store house. Plate XXIV, b, shows an old onion,
gathered outdoors in the spring, with several of these black
sclerotial bodies.
Not being able to predict the character of the season as to its
moisture, experiments to determine the value of spraying in pre-
venting stem rot in White Globe onions were undertaken the
past year on the farm of W. H. Burr at Green's Farms. As it
turned out, there was no stem rot, so no information regarding
the value of this treatment for the rot was gained, yet some
points of value regarding spraying onions were obtained. Four
or five treatments were planned, but on account of sickness only
three were made, on June 24th, July 5th, and August 3d. Dif-
ferent plots of the onions were sprayed once, twice, three times
and not at all. Onions are planted so closely together in the
fields that no apparatus drawn by a horse can be used. In this
experiment knapsack sprayers were used. These, however, are
so cumbersome that they meet with little favor where any con-
siderable spraying is to be done. The small barrel pump,
mounted on wheels somewhat higher than usual, to bring the
bottom of the barrel nearly clear of the tops of the onions, no
doubt would be the best apparatus where any considerable
322 CONNECTICUT EXPERIMENT STATION REPORT, I904.
spraying is to be done. One man can then pump and pull the
barrel and another spray several rows of onions as they go
along. The first treatment need not be made before the first
week in July, since the plants are rather small before this time,
and there is little danger of fungus troubles until then. It is
very difficult to make Bordeaux mixture adhere to onions be-
cause there is very little surface, but chiefly because of the
very smooth, glaucous character of this surface. This makes
it almost necessary to use resin Bordeaux to secure fair results.
Soap added to the ordinary Bordeaux proved of little value.
Even with resin Bordeaux the glaucous character of the tops
prevents the spray from adhering any length of time if there
is rainy weather. This being the case, at least four or five
sprayings will be necessary to secure moderate protection against
any serious fungous trouble. With all these difficulties and
objections it is not likely that spraying onions against fungous
trouble, unless very serious, will come into very general use.
The onions sprayed in this experiment were stored separately,
but very little difference was noticed in their keeping qualities,
and no true stem rot developed.
PEACH, Prunus Persica.
Brown Rot, Sclerotinia fructigena (Pers.) Schrot. Plate
XXIV, c-d. Because of the light crop for two years the brown
rot of peach was not especially prominent. Search last spring
brought to light, for the first time in this state, the presence
of the Sclerotinia, or asco-spore stage (see illustrations) on
the old mummies partly buried in the ground. While these
were not very common, they were found on both peach and
plum mummies, and are no doubt more common when more of
the rotten fruit is left on the ground. They serve as another
means of infecting the young blossoms in the spring and thereby
spreading the trouble to the fruit.
Frosty Spots. In August there were sent to the Experiment
Station from Cannon Station diseased leaves of peach which
showed in their first stage a purplish discoloration of the under
surface and later a silver grey color as if mildewed. Sections
of the diseased leaves, however, showed no fungus present, but
did show that the epidermal cells and later the spongy paren-
chyma cells beneath had turned purplish, finally lost their con-
tents and collapsed. The injury, apparently, was a physiologi-
NOTES ON FUNGOUS DISEASES FOR I904. 323
cal trouble caused by some unusual disturbance of natural
conditions. Possibly it was due to insufficient water supply
brought about through winter injury to the roots. Lack of
water as a cause was suggested by the trouble showing first
in the vicinity of the bundles, through which the water is
brought, and by its occurrence on the under surface of the
leaf where the stomates are, which regulate the transpiration
of the water. A very similar trouble was noted in the Report
for 1903, p. 360, on strawberry leaves.
Winter Injury. Many peach orchards were severely hurt by
the winter of 1903-4. In most cases the wood was injured,
usually down to the snow line, as shown by the darker color,
without damage to the bark and cambium. Many trees had been
similarly injured the year before, and so formed very little
new wood the past season. Occasionally the trunks of older
trees were split toward their base with prominent longitudinal
cracks. In one orchard the injury was confined chiefly to the
roots of certain trees. In the spring these trees put out a
scanty, yellowish, sickly foliage. Examination showed the
trunks generally healthy, but the roots injured or dead. The
innermost vertical roots were always least injured, as they were
more protected than the outer more horizontal roots. Appar-
ently only those trees had suffered where the snow had blown
off the most exposed places in the orchard, which was on a
hill side. Many growers in the spring severely trimmed their
trees and dug out those very badly injured. Undoubtedly the
peach can stand severe winter injury to its wood and still make
a slight growth of new wood the next year. Just what the
ultimate value of these trees will be, however, is a point not
yet settled. So far as observed by the writer, trees that were
• injured did better when severely pruned than when not pruned.
See apple, also Report, 1903, p. 341.
PEAR, Pirns communis.
Scab, Venttma pirijia CLih.) Aderh. Plate XXV, a-c. This
disease was not especially bad the past season, but is mentioned
because the scab stage was found on the twigs of certain trees ;
see illustration. The occurrence of the fungus on the twigs
is more common with pear than with apple scab. In the cases
examined, the bark was more or less corroded or pustular at
the infected places. Usually the outbreaks, especially in a fruit-
324 CONNECTICUT EXPERIMENT STATION REPORT, I904.
ing condition, were found only on tlie one and two-year-old
twigs. On the older twigs apparently the diseased bark
gradually sloughed off and was replaced by a healthy growth.
There was some indication that the mycelinum passed from last
year's to this year's twigs, since on the latter the outbreaks
often appeared first and most abundantly at their basal end.
Undoubtedly, however, new infections often and possibly always
take place by reinfection of the young twigs from spores pro-
duced on the older. In the winter time the scab areas may
show plenty of the spore-bearing mycelium, but no spores,
which begin to form early in the spring. Certain varieties
are known to scab much worse than others, and in these cases
it is probably largely because the fungus readily becomes estab-
lished on the twigs. This being the case, spraying the dormant
wood in the spring should have some effect in retarding and
lessening the trouble. Observations made on certain trees
sprayed last winter with lime and sulphur showed them freer
the following summer from scab than usual, probably for this
reason.
PLTJM, Prunus sps.
Brown Rot, Sclerotinia fructigena (Pers.) Schrot. The
Sclerotinia stage was found for the first time in this state on
the mummied fruit half buried in the ground. See peach.
POTATO, Solanum tuberosum.
Bacterial Disease, (?) Bacillus Solanacearum Sm. Plate
XXVII, a-b. The bacterial disease of potato stems mentioned
in the Report of 1903, p. 351, was found again this season.
This trouble appears early in June. Usually a plant here and
there in the field is injured, but the disease does not seem to
spread as the season advances. Diseased plants can usually be
identified by their yellowish foliage and often dwarfed growth.
Very badly diseased plants can be pulled easily from the soil, the
underground stem being rotted (Plate XXVII, a) and few roots
or tubers are developed. Sometimes these stems look as if
attacked by borers, the pith within being rotted and hollowed
out for some distance. Above the rotted part cross sections
of the green, apparently healthy, stem usually show the bundles
darkened and diseased when the rest of the tissues are healthy ;
see Plate XXVII, b. In these bundles there is found an abun-
NOTES ON FUNGOUS DISEASES FOR I9O4. 325
dance of bacteria. The Rhizoctonia fungus sometimes girdles
places on the underground stem (see Plate XXVI, b) and may
easily be confused with this trouble. The disease is apparently
the southern tomato blight, described on tomatoes and potatoes
in last year's report. Whether this trouble subsequently devel-
opes as the common soft rot of the tubers is a question not
settled in the writer's mind. If so, it then becomes a serious
disease in this state.
Downy Mildew (Blight), Phytophthora infestans (Mont.)
DeBy. This trouble was very late in appearing and did no
damage to the foliage of early varieties and but little to the
late. The tubers, especially of the late varieties, however, rotted
very badly. (See special article in this Report on the potato
blight.)
Rhizoctonia (Rosette), Corticium vagitni var. Solani Burt.
Plate XXVI, a-c. Last spring the small black sclerotia of the
sterile Rhizoctonia stage of this fungus were very common on
tubers used for seed ; Plate XXVI, a. Again this spring, 1905,
the seed tubers were abundantly covered with these sclerotia.
Such tubers if used for seed will yield a crop similarly infected,
just as do scabby tubers, as was shown last season in a small
experiment with infected and free tubers. So far as appear-
ance goes, these sclerotia do very little harm since they are
rather obscure and often resemble dirt. They become evident
when one attempts to wash the tuber, as they do not wash off
and the water brings out more strongly the contrast between
their black color and that of the skin. An examination of the
fields early in June showed the fungus present, the Corticium,
or fruiting stage (Plate XXVI, c) being found then for the first
time in this state. The mycelium, developed from the scle-
rotia, certainly grows out on the young stems and roots.
Sometimes it produces diseased or girdled areas, as shown in
Plate XXVI, b. When the mycelium reaches the stem just at the
surface of the ground, it developes for a short distance a more
abundant but still rather inconspicuous greyish mealy growth.
This is the fruiting or Corticium stage and no injury is done
to the stem here, as the fungus does not penetrate the tissues, but
loosely covers the stem with a coating that gradually wears off
as the spores are matured, and eventually disappears. Several
fields were examined which showed from 15 to 20 per cent, of
the plants having the Corticium stage on some of their stalks.
26
326 CONNECTICUT EXPERIMENT STATION REPORT, I904.
Apparently the plants did not suffer so severely from the
fungus as some writers claim they do elsewhere. However,
the relative injury caused here by this fungus is a subject that
needs further attention, since with the parts attacked occurring
under ground the injury and cause can easily escape notice.
See Report, 1903, p. 350, for further description and treatment.
In the writer's opinion there is no doubt that the Corticium
stage is the same fungus described by Prillieux and Delacroix
of France [Soc. Myc. 7:220] in 1891, as Hypochnus Solani.
They did not recognize its relation to the Rhizoctonia stage,
Rhizoctonia Solani Kiihn, which has been known in Europe
for some time.
Scab, Oospora scabies Thaxt. Considerable complaint was
made of the damage caused by this fungus, which was unusually
prevalent in 1904. See Report, 1903, p. 350, for treatment.
PRIVET, Ligustrvim Japonicum.
Winter Injury. Plate XXVII, c. The California privet
hedges were generally injured by the severe winter of 1903-4.
In most cases the stems were killed down to about a foot from
the ground. This injury apparently extended down to the
snow line, which completely protected the parts below, since
young hedges less than a foot high were not injured at all.
There was some question among owners of these hedges as
to what treatment should be given them. The best treatment,
apparently, is to wait until the new growth begins to start in
the spring and then trim back evenly to the uninjured portion.
Plate XXVII, c, shows an injured hedge on the Experiment Sta-
tion ground after the new growth had made a fair start and
illustrates the trimming necessary in this case to remove the
injured stems. As the roots of the hedges were rarely injured,
the plants, when properly trimmed, made so vigorous a growth
that often by midsummer all indication of injury had been
obliterated.
RADISH, Raphanus sativus.
Root Rot, Rhizoctonia sp. Plate XXVIII, a, shows speci-
mens, received from Elmwood, of greenhouse radishes that
were severely injured by a dampening off and root rot trouble.
This was caused by the sterile mycelium of a Rhizoctonia fungus
which undoubtedly becomes established in the soil, and when
NOTES ON FUNGOUS DISEASES FOR I904. 327
this is kept damp injures the underground parts of various
plants. It is quite probable, for instance, that the stem rot
of rhubarb, mentioned later, and possibly even the Rhizoctonia
of the potato, is caused by this same fungus. In the Experi-
ment Station greenhouse certain specimens of the cigar plant
have been injured recently by a similar agent. In previous
years other greenhouse plants have been attacked. Last spring
young radishes in the New Haven market not infrequently had
conspicuous, but shallow, injured spots on them which appar-
ently had also been caused by the Rhizoctonia fungus. See
Report 1903, p. 345.
RASPBEREY, Rubus sps.
WiLT^ Leptosphaeria Coniothyrium (Fckl.) Sacc. For three
years a small patch of berries at North Haven has been injured
by a wilt of the fruiting stems, which wither and die just as the
berries begin to mature. The trouble has increased in severity,
killing out most of the Palmers on which it started and finally
appearing on the Kansas variety, several rows removed. The
trouble apparently is caused by the above fungus girdling the
stems or producing dead areas on them. Last May the para-
sitic pycnidial stage and the saprophytic asco-spore stage were
both found on the stems. The former was especially abundant
on the tips of the pruned stems. Probably this trouble is not
uncommon in the state, though not often reported. See Report
1903, P- 355-
Winter Injury. Complaint was made by one grower that
part of his raspberries had leaved out in the spring, but after-
ward had sickened and died. Examination of specimens
received showed no sign of a fungus. The injured plants were
on an exposed hill, where the winter's winds swept the ground
bare of snow. Apparently the roots were severely injured or
killed during the winter, while the stems were not, so they were
able to leaf out but not to develop any further. The injury in
some respects resembles the wilt disease.
RHUBARB, Rheum Rhaponticum.
Stem Rot, Rhizoctonia sp. Plate XXVIII, b, shows the
base of leaf petioles with dark sunken cankers apparently caused
by the sterile mycelium of the Rhizoctonia fungus which was
328 CONNECTICUT EXPERIMENT STATION REPORT, I904.
present at these places. These specimens were sent from
Southington, and a similar trouble was found on plants in New
Haven. In the latter case the petioles sometimes rotted at the
base and the leaves turned yellowish, wilted and finally died.
SWEET WILLIAM, Dianthus barbatiis.
'R.TJST, Puccinia Arenariae (Schum.) Schrot. Plate XXVIII,
c. This rust was found for the first time in the state this year
in some seedling plants grown in a yard in Westville. Only
certain kinds of the seedlings were infected and the trouble
apparently did not spread to the others in the same bed. This
fungus, like the hollyhock rust, possesses only the teleuto spores
which may germinate in situ as soon as formed and thus spread
the disease.
TOBACCO, Nicotiana Tabacum.
Canker (Black Spot*). This and the following are two
warehouse troubles of tobacco not mentioned in our last Report.
They appear in the leaves after these have been packed in cases
for fermentation. Canker is apparently a fungus trouble in
which dark colored patches are produced that often extend down
through the leaves of several overlapping hands. The injured
tissues are dark colored, become brittle and easily fall to pieces.
Microscopic examination reveals the presence of abundant but
isolated purplish black spores, apparently those of Sterigmato-
cystis niger. It is not known just what conditions favor the
development of this trouble, whose presence is not known until
the cases are opened for examination. Probably too much
inoisture favors its development, especially if care has not been
used in selecting and packing the tobacco.
Must is a fungus or bacterial trouble also developed in the
packed tobacco and is named from its musty odor. Examina-
tion of specimens sent the writer from East Hartford showed
the presence of a slight whitish growth, especially along the
midribs. Numerous bacteria and also some molds were found
in these growths. Cultures from a specimen placed in a damp
chamber produced a reddish brown mold. Sometimes the
dealers renovate musty tobacco by washing the leaves with rum.
* Loew, O. Physiological Studies of Connecticut Leaf Tobacco. U. S.
Dept. Agr. Rept. 65 : 48. '
Alfalfa.
PLATE XVIII.
a. Leaf Spot, p. 311.
Apple.
b. Powdery Mildew, p. 311. c Rust, p. 312.
FUNGI OF ALFALFA AND APPLE.
PLATE XIX.
a. I Rust.
b. I Rust. X 2.
c. II Rust. X 2. d. Rust Parasite. X 2.
FUNGI OF ASPARAGUS, pp. 313-15.
PLATE XX.
Lima Bean.
a. Bacterial Spot of cotyledons, p. 316.
b. Brown Rot of fruit, p. 316.
DISEASES OF LIMA BEAN AND CHERRY.
Dewberry,
PLATE XXL
Ess Plant.
a. Orange Rust Parasite, p. 318.
b. Wilt, p. 318.
Fig.
c. Smutty Mold, p. 318.
FUNGI OF DEWBERRY, EGG PLANT, FIG.
PLATE XXII.
.%s-
: '^^
a. Showing white mycelium and minute black perithecia on leaf. X 2.
b. On the fruit.
c. On the fiuitins; stem.
POWDERY MILDEW OF GRAPE, p. 319.
PLATE XXIII.
Mulberiy, p. 319.
a. Bacterial disease on leaf.
b. Bacterial disease on stems.
Musk Melon.
c. Bacterial Rot of fruit, p. 320.
BACTERIAL DISEASES OF MULBERRY AND MUSK MELON.
PLATE XXIV.
Stem Rot of Onion, p. 321.
a. End view of rottine; bulb.
b. Sclerotia on decayed bulb.
Peach, p. 322.
X 2.
c.-d. Sclerotinia stage of Brown Rot appearing" on mummied fruit.
FUNGI OF ONION, PEACH.
PLATE XXV.
a. On the leaf.
b. On the fruit.
c. On the twigs producing cankered placesin barl
PEAR SCAB, p. 323.
PLATE XXVI.
a. Rhizoctonia sclerotia on tuber.
^:^f
b. Cankered area on underground stem. c. Corticium stage on stem just above ground.
RHIZOCTONIA FUNGUS OF POTATO, p. 325.
PLATE XXVII.
Bacterial disease of Potato, p. 324.
^ *^
#
a. Diseased root.
b. Cross section stem.
Privet.
c. Winter injury of California privet hedge, p. 326.
TROUBLES OF POTATO, PRIVET.
PLATE XXVIII.
a. Rhizoctonia injur}' to roots, p. 326.
Sweet William.
Rhubarb.
b. Rhizoctonia injury, p. 327.
c. Rust, p. 32S.
FUNGI OF RADISH, RHUBARB, SWEET WILLIAM.
BLIGHT OF MUSK MELONS AND CUCUMBERS. 329
DOWNY MILDEW, OR BLIGHT, Peronoplasmopara
Ciihensis (B. & C.) Clint, OF MUSK MELONS
AND CUCUMBERS.
HISTORICAL AND SYSTEMATIC CONSIDERATION.
Early Record. The downy mildew, or blight, of cucumbers,
musk melons, and other cucurbits was first described in 1868 by
Berkeley of England from specimens collected by Wright on
a cucurbitaceous plant in Cuba. He named it Peronospora
Cubensis B. & C. The description given was very meagre and
the species was not regarded of special economic importance.
Nothing more was heard of it until 1889, when Halsted (13)
noted in the Botanical Gazette that a serious Peronospora
trouble had been found on greenhouse cucumbers in New
Jersey. He did not specifically identify the fungus. The same
year Farlow (lo), having seen Halsted's specimens, reported
the fungus as Peronospora Cubensis B. C. and also stated that
he had received specimens on cucumbers and another cucurbi-
tj^ceous plant, collected the previous year in Japan, sent to him
by Miyabe, who had recently examined the Berkeley and Curtis
type specimens at Kew and found them to be the same. Late
in this year Halsted (14) reported that the fungus had been
injurious on cucurbits grown outdoors in New Jersey, giving
as hosts squash, pumpkin and cucumbers ; and Galloway (11)
reported it as a serious pest of cucumbers in Florida and Texas.
Humphrey (28) reported the fungus injurious to cucumbers
and squashes in Massachusetts in 1890; and Thaxter (61)
found it the same year on cucumbers at South Manchester in
this state.
Recent Record. Since first found by Halsted this ftmgus has
been reported nearly every year by some one in the United
States though not discovered elsewhere until recently. The
fungus, however, has not been so common here in some years
as in others, and seems to have periods of vigorous develop-
ment for a year or two, then gradually disappearing from con-
spicuous view. Apparently in 1896 and 1897, it was more seri-
ous than usual, especially on cucumbers, as it attracted especial
investigation in these years from Stewart (53) of the New
York and Selby (44) of the Ohio Experiment Station. Again,
330 CONNECTICUT EXPERIMENT STATION REPORT, I904.
beginning about 1901, and reaching its climax in 1902, it was
specially destructive in New England on musk melons and
cucumbers. In 1903 the fungus was not especially prominent
in this state, while in 1904 it was scarcely to be found.
In 1899 Massee (36) stated that the fungus had recently
been introduced in England, on Cucurbita pepo and Cucumis
sativus, from Japan. This seems to have been its first appear-
ance, or at least discovery, in any European country, though
recently it has attracted considerable attention in Russia and
the Mediterranean region. Rostowzew (40) gives an account
of its injury (in 1902) to cucumbers in the province of Twer,
Russia, and the next year, as reported by Linhart (35) from
Hungary and by Hecke (24) from Austria, certain cucumber
and melon fields of Austro-Hungary were seriously injured.
Saccardo (42) and others also reported it injurious in 1903
to cucurbits in Italy.
Hennings (26) stated in 1902 that the fungus was collected
in Brazil in 1900. Zimmermann (65) also in 1902 described
the fungus as a new variety from Java, and a year later listed
it from Dutch East Africa.
Hosts and Distribution. All of the hosts upon which this
downy mildew has been found belong to the cucurbit family,
and nearly all of the reports of its occurrence have been on
the cultivated species. Selby has reported it in Ohio on Sicyos
angulata and Echinocystis lobata, two wild species common in
the United States, but he notes that it escaped to these from
a cultivated field near by. Others have looked for the fungus
on these hosts, but have not found it, so it seems probable that
they are not original hosts in the United States. Apparently
the fungus is not a native of this country, but introduced, prob-
ably, from the West Indies, first in the southeastern states.
Cuba may have been its original home, or it may have had inde-
pendent origin in several places. The following distribution is
taken chiefly from the literature of the fungus, together with
the hosts and name of the person reporting:
Cuctcrbitaceae: Cuba, type (Berkeley), Japan (Farlow) ;
Citrullus vulgaris, water melon. Conn. (Halsted), N. J. (Hal-
sted), Ohio (Selby), Hungary (Linhart) ; Cucumis Angaria,
gherkin gourd, Fla. (Swingle), Tex. (Swingle) ; Cucumis
Melo, musk melon. Conn. (Sturgis), 111. (Clinton), Mass.
BLIGHT OF MUSK MELONS AND CUCUMBERS. 33 1
(Stone), N. H. (Lamson), N. J. (Halsted), N. Y. (Stewart),
Ohio (Selby), R. I. (Stene), Hungary (Linhart), Italy (Sac-
cardo) ; Cucumis sativus, cucumber, Conn. (Thaxter), DC.
(Galloway), Fla. (Galloway), 111. (Burrill), Ky. (Garman),
Mass. (Humphrey), Md. (Swingle), Mich. (Orton), N. H.
(Lamson), N. Y. (Stewart), Ohio (Selby), Penn. (Orton),
R. I. (Stene), S. Car. (Orton), Tex. (Galloway), West Virg.
(Orton), Austria (Hecke), Brazil (Hennings), Dutch East
Africa (Zimmermann), England (Massee), Hungary (Lin-
hart), Japan (Farlow), Russia (Rostowzew) ; Cucumis sativus
var. Anglicns, English cucumber. Conn. (Clinton) ; Cucurhita
sps., squash, Mass. (Humphrey), N. J. (Halsted), Ohio
(Selby) ; Cucurhita moschata, winter crook-neck squash, N. Y.
(Stewart) ; Cucurhita pepo, pumpkin, etc., N. J. (Halsted),
Ohio (Selby), England (Massee), Java (Zimmermann);
Echinocystis lohata, wild cucumber, Ohio (Selby) ; Sicyos
angulatus, star cucumber, Ohio (Selby). Besides these hosts
Selby of the Ohio Experiment Station in 1899 planted in a
disease garden a large number of cucurbits to determine if the
fungus would develop on them. It spread from the usual
hosts upon the following not reported above: Cucumis odora-
tissimus, Cucumis erinaceus, Cucurhita Melopepo, Cucurhita
verrucosa^?), Lagenaria vulgaris, Coccinia Indica, Bryonopsis
laciniosa erythrocarpa, Mukia scahrella, Momordica halsamia,
Momordica Charantia, Melothria scahra, Trichosanthes colu-
hrina.
Systematic Position. Berkeley's original description of this
fungus is so vague that it is only upon the authority of Miyabe,
who has examined the specimens, that we are sure of its
identity with the specimens since collected. Berkeley placed
it under the genus Peronospora, calling it Peronospora Cuben-
sis B. & C. Both Halsted and Tanaka (see Farlow 10)
observed the germination of the spores, which was by zoo-
spores. Humphrey also reported germination by zoospores, and
as this type of germination is not characteristic of Peronospora,
whose spores germinate through germ tubes, but of the genus
Plasmopara, he renamed the fungus Plasmopara Cuhensis (B.
& C.) Humph., but at the same time called attention to the
fact that it possessed characters common to both genera. A
number of botanists have since made a more or less thorough
332 CONNECTICUT EXPERIMENT STATION REPORT, I9O4.
1
study of the fungus and have placed it under one or the
Other of these genera, sometimes indicating doubt as to its real
position.
Waite, for instance, in the Journal of Mycology in 1892,
called attention to its resemblance to his new species, Perono-
spora celtidis and said : "The conidiophores of P. celtidis
while of the type of Peronospora may be regarded as a step
toward Plasmopara. . . . Mr. W. F. Swingle has pointed
out to me that Peronospora cubensis B. & C. resembles P. cel-
tidis quite closely and is its nearest ally and that these two
species form a group by themselves, differing considerably
from either Peronospora or Plasmopara. Both have long
very dark conidia, pointed at each end and germinate by zoo-
spores, with conidiophores of the so-called dichotomous type
and strongly hygroscopic. For the present the form on Cel-
tis is thought to be best placed in the genus Peronospora."
Swingle, in an article on American Peronosporaceae in the
same number of the Journal, places these two species under
Peronospora in a doubtful section. A step further than this
was taken by Berlese (4) in 1901, when he created a new sub-
genus, Perono plasma para Berl., of the genus Plasmopara, espe-
cially for these two species.
Zimmerman (65), in 1902, described a new variety of the
fungus from Java, collected on leaves of Cucurbita pepo, call-
ing it Peronospora cubensis var. atra. This author labored
under the impression that the spores of P. Cubensis were hyaline,
as has been stated by some authors, while those of his speci-
mens were a dark grey, and so he made the variety on this dif-
ference. He also stated that their germination in water was by
germ tubes. Unless the germination is always through germ
tubes there seems to be no reason for considering the Java
specimens distinct from those reported elsewhere.
Recently Rostowzew (40), a Russian botanist, has studied
the fungus more in detail than any of the preceding investi-
gators and has decided, like many of them, that it does not
agree exactly either with Peronospora or Plasmopara, but has
intermediate characters. So he has created a new genus,
Pseiidoperonospora, for it. While this author contrasts and
compares the type of this genus with Peronospora and Plasmo-
para, he makes the mistake of not giving a brief scientific
BLIGHT OF MUSK MELONS AND CUCUMBERS. 333
description of his new genus, so that one is left somewhat in
doubt as to just what its chief characters are. He does state,
however, as have others, that its type species agrees with Pero-
nospora in the character of the branching of the conidiophores
and with Plasmopara in the conidia having an apical papilla
and generally germinating by zoospores. Rostowzew also
described the Russian form as a new variety, calling it Pseudo-
peronospora Cuhensis var. Tweriensis Rostow. He had
American specimens with which to compare his and found the
following supposed differences : i st, The Russian variety
formed a more luxuriant, felt-like, growth on the leaves ; 2d,
the conidiophores were usually 2 or 3 or even 3 to 7 at a
stomate while the American specimens had i or 2 ; and 3d, the
conidia averaged slightly larger.
These points, if fairly constant, would without doubt entitle
the Russian specimens to distinct varietal rank. Upon look-
ing over American material, however, the writer finds that
there is considerable variation, and it seems quite probable that
Rostowzew's specimens from here did not show this. For
instance, on the water melon there is usually no evident growth
of the fungus ; on the musk melon it often becomes evident
especially at the juncture of diseased and healthy tissue ; while
on the cucumber, upon which host the Russian variety oc-
curred, one often finds a very evident tinted growth on the
under side of the leaves, especially when the weather condi-
tions have been favorable for its development. Again, while
the conidiophores are usually i or 2 at a stoma in American
specimens, the writer has frequently found 3 or 4 in some speci-
mens, and Stewart (53) of New York says, "the number of
sporophores which proceed from a single stoma is small, usually
one or two ; but it is not uncommon to find as many as five and
even larger numbers are occasionally seen." Finally, the writer
has measured spores from the musk melon that averaged as
large, or larger, than the average and the large measurements
given by Rostowzew for his variety. It seems from these com-
parisons that the Russian form is not distinct, especially since
the other European specimens have not been so considered.
Along with others the writer has had difficulty in placing
this species generically, but after a careful consideration of
334 CONNECTICUT EXPERIMENT STATION REPORT, I904.
the subject is in favor of a distinct genus for it. The only
objection to this is that possibly a critical study of all of the
species of Peronospora and Plasmopara, especially as to their
germination, might show that these genera grade into each other
through so many forms that an intermediate genus would only
magnify the difficulties of generic distinctions. Berlese's sub-
genus, Peronoplasmopara, because of priority of publication
and also because it was given definite descriptive characters,
seems to merit precedence over Rostowzew's rather indefinite
Pseudoperonospora. Elevating P eronoplasmopara to generic
rank, the distinctive characters of these three genera, in the
writer's opinion, are as follows :
Peronospora Cda. Conidiophores chiefly of the dichotomous
or modified dichotomous type of branching; with branches
spreading mainly at acute angles, the ultimate spore-bearing
tips being separate and sub-acute. Conidia hyaline or tinted,
small to large, epapillate and germinating by germ threads.
Haustoria usually conspicuous, branched and filiform, more
rarely abbreviated and simple.
P eronoplasmopara Berl. Conidiophores of the dichotomous
or modified dichotomous type of branching ; with branches
spreading mainly at acute angles, the ultimate spore-bearing tips
being separate and sub-obtuse. Conidia chiefly large, tinted
(violet chiefly), with a conspicuous papilla of dehiscence and
germination typically by zoospores. Haustoria small and
usually simple. Types: P eronoplasmopara Cubensis (B. & C.)
Clint., P eronoplasmopara Celtidis (Waite) Clint.
Plasmopara Schrot. Conidiophores chiefly of the mono-
podial type of branching, with the successive shorter side
branches (and their sub-branches) given off chiefly at right
angles to the main branch, and with the ultimate, spore-bearing
tips truncate and often somewhat clustered at the swollen ends.
Conidia chiefly small, hyaline, papillate, and germinating by
zoospores. Haustoria small, chiefly ovoid.
Specific Description. Since this species has been described
rather meagerly and imperfectly, we give the following descrip-
tion, based on an examination of abundant material, and include
references to synonymy and exsiccati :
BLIGHT OF MUSK MELONS AND CUCUMBERS. 335
Peronoplasmopara Cubensis (B. & C.) Clint, n. comb.
Peronospora Cubensis B. & C, Journ. Linn. Soc. Bot. 10:
363. 1868.
Plasmopara Cubensis Humph., Ann. Rept. Mass. Agr. Exp. Stat.
8: 212. 1891.
Plasmopara {Peronoplasmopara^ Cubensis Berl., Riv. Pat. Veg.
9: 123. 1901.
Peronospora cubensis var. atra Zimm., Centr. Bak. Par. Infekt.
8: 148. 1902.
Pseudoperonospora Cubensis Rostow., Flora 92: 422. 1903.
Pseudoperonospora Cubensis var. Tweriensis Rostow., Flora 92:
422. 1903.
Exsiccati : Peronospora Cubensis B. & C, on Cucumis sativus,
S^ym. & Earle Econ. Fungi 41, Ell. & Ev. N. A. F. 2426 a,
on Cucurbita sp. (squash), Ell. & Ev. N. A. F. 2426b; Plas-
m,opara Cubensis (B. & C.) Humph., on Cucumis sativus, Syd.
Phyc. et Prot. 119, Barth. Fungi Col. 1840, on Cucumis Melo,
D. Sacc. Myc. Ital. 1276. ?[K. Posch Fungi Par. Exs. Plant.
Cult. Hungariae.]
At first forming yellowish, rather indefinite discoloration of
the leaves, but often finally producing definite reddish brown
(sometimes purplish beneath) dead areas of varying size scat-
tered over the leaves. Outbreaks of fungus chiefly hypo-
phyllous, often invisible or evident only at margin of the spots,
but sometimes forming a conspicuous purplish growth. Coni-
diophores chiefly i or 2, occasionally 3 or 4, rarely more, from
a stoma, 180 to 400;". in length by 5-9 /^ in width, often with
a slightly swollen base, 2-5 (chiefly 2-4) dichotomously (some-
times imperfectly) branched from upper third of length, with
ultimate spore-bearing tips tapering, slightly curved, blunt, and
5-20 )u, long by about 2/x wide. Conidia olive brown to grayish
purple, chiefly ovoid to ellipsoidal, with evident papilla of
dehiscence and sometimes with remains of pedicel of attach-
ment, 2i-39ja by 14-23/X, though chiefly 23-30/x, by i6-20/x.
? [Oospores spherical, yellowish, warty papillate, 30-43/*, matur-
ing only after leaves decay in the ground, according to
Rostowzew.]
Hosts and Distr. : on various Cucurbitaceae, especially on
cultivated species, reported from United States, Cuba (type),
Brazil, England, Russia, Austro-Hungary, Italy, Japan, Java,
Dutch East Africa.
336 coxxecticut experiment station report, i9o4.
Life History.
Myccliuni. The mycelium consists of hyaline, somewhat
irregtilar. branched threads, about 5-5-5.7 /^ iu diameter, that
push their way between the cells of the leaf. These mycelial
threads are found more abundantly on the lower side in the
spongy parenchyma than in the palisade, or closely packed, cells
of the upper leaf tissues. The cellulose walls are moderately
thin and septa are rarely found. Protoplasmic contents at first
fill the threads, but later they may become empty, especially
in the old dead tissues. The threads reach the surface of the
leaves usually on the under side, pushing their way through the
stomates or more rarely boring directly through the epidermis.
Here they give rise to the conidiophores, apparently developing
one to several at the same time, or subsequently, according to
weather conditions. ^Mien the tissues have become severely
injured or killed, the production of conidiophores gradually
ceases and new ones are then formed, chiefly at the margins of
the enlarging injured areas.
The mycelium penetrates the cells of the interior of the leaf
only by short ovate haustoria. These were first described and
figured by Humphrey (28). It is rather difiicult to make them
out. since they are often obscured by the cell contents. Ros-
towzew found that they lacked the cellulose wall of the mycelium
and that often they developed finger-like processes from their
swollen tips. The object of the haustoria, of course, is to take
food from the plant cells for the growth of the fung'us.
Conidiophores. The conidiophores are the spore-bearing
branches of the fungus, and from one to rarely five or six
develop from a single stoma. AA'hen produced abundantly they
make an evident gTowth on the exterior of the leaf. They are
simple for about the lower two-thirds of their length and dicho-
tomously branched at the upper third. This branching is not
always exactly dichotomous, for sometimes one branch is larger
and tends to continue as the main stem. The branches separate
usually at acute angles and may be similarly sub-divided several
times, usually two to four times. The main stem of the coni-
diophere is 5.5 to 9.5/x wide, with the base often slightly
swollen just above the stomate, and then it is sometimes even
ii/x. wide here. The stem and branches very gradually narrow
upward so that the ultimate, conidia-bearing tips are about 2/1,
LIFE HISTORY OF MELON BLIGHT. 337
or less in width. These tips or final branches vary from 5.5 to
14/A (rarely longer) in length and are usually slightly curved
and taper somewhat to a bluntish apex. A single spore is borne
on the end of each branch, which readily drops off when mature,
especially if the conidiophore is placed in water. According to
Rostowzew, the ultimate branches end in temporary sterigmatal
tips that lack cellulose and dissolve in water, thus freeing the
spores. The walls of the conidiophores certainly contain cellu-
lose, as shown by color reaction with chloroiodide of zinc, and
sometimes the extreme tips fail to color and often after the
spores fall off are blunt. These points may indicate the
fugacious sterigmata of Rostowzew, but if so these organs are
not very completely differentiated. The conidiophores vary
greatly in length, probably depending on weather conditions at
time of their formation or possibly on the number produced from
the same stoma. The extreme lengths observed were 140/x and
41OJU, with the average lengths about half way between these.
The branching of the short conidiophore often begins lower
down than the upper third, while that of the longer form may
begin above this point. When young the conidiophore is filled
with a uniform protoplasmic content, but as the spores are
formed this gradually disappears from the base upward and is
all gone when spore production ceases. With this disappear-
ance of the protoplasm a septum or so is rarely formed in the
conidiophore.
Siiuuncr Spores, or conidiospores, or temporary sporangia, as
they are variously called, are formed, as stated above, on the
tips of the ultimate branches of the conidiophores. When small
these are hyaline, but they very soon assume a greyish or olive
purplish color. When looked at with a hand lens they may
even appear purple black. Some authors have incorrectly
described them as hyaline, and of course as seen under the
high powers of the microscope they are much lighter in color
than when seen with a hand lens, but even then they always
appear strongly tinted. They vary in shape usually from ellip-
soidal to ovate, but occasionally are even subspherical. Speci-
mens examined by the writer from the musk melon averaged
longer and proportionately narrower than those from the
cucumber. The measurements varied from 21-39/x in length
and 14-23 /x in width, while the average sizes were about 23-30/u,
338 CONNECTICUT EXPERIMENT STATION REPORT, I904.
by 16-20/A. The spores have a uniform, rather thin wall, except
at their apex, where there is an evident hyaline papilla of
dehiscence, while at the base there is more or less evidence of
the point of attachment. Except at these two points the cell
wall gives the cellulose reaction when tested with chloroiodide
of zinc.
Germination of Spores. The germination of the spores
through zoospores has been mentioned by a number of writers,
but no one has figured or carefully described this method.
When placed in a drop of water in a Van Tiegham cell the
spores sometimes started to germinate inside of two to four
hours if they were in good condition. Many of the attempts to
germinate the spores failed altogether, probably because in
ordinary dry weather the spores very soon lose their power of
germination. Generally they were successful where fresh
spores, developing in a moist atmosphere, were used. In all
cases the germination was by means of zoospores. Occasion-
ally a faint division of the protoplasmic contents into areas (see
Plate XXXI, 5) could be seen before the zoospores were dis-
charged, but it was difficult to distinguish anything like separate
zoospores even when apparently completely differentiated. The
zoospores suddenly begin to escape from the spores through a
pore formed by the dissolution of the papilla of dehiscence.
Usually they were completely differentiated and escaped one at
a time, swimming off immediately after their release ; more
rarely they escaped into a bunch just outside of the spore, from
which they very soon isolated themselves and swam away.
The pore by which they escape is too small to admit their
unhindered passage, though they quickly push their way
through, their plastic body admitting the necessary contraction
for this. Plate XXXI, 6 shows the dumbbell shape assumed by
a zoospore when half way through the opening. Rarely one of
the zoospores fails entirely to escape and may finally germinate
inside the spore, Plate XXXI, 7.
The zoospores very soon after escape lose the plasticity of
the body wall and assume their permanent shape. This is
somewhat turtle-like ; that is, oval in dorsal view (that usually
seen), but with side view more elongated, showing the dorsal
aspect convex and the ventral often slightly concave. Two
elongated cilia are attached to the ventral surface. These are
LIFE HISTORY OF MELON BLIGHT. 339
too fine to be detected without staining, but one is carried for-
ward and the other extends to the rear. The protoplasmic con-
tents of the zoospores are rather uniform, but often with granules
of a more highly refractive index and with a prominent vacuole
toward the forward end. The zoospores swim forward with a
swift, gliding motion, often at the same time revolving more
slowly around their elongated axis. At first they are very
active, rarely remaining at rest long enough for one to measure
them accurately, but their length is about 12 to i8|tt. After an
hour or two, or perhaps sometimes even considerably longer,
they become more sluggish in their movements and gradually
come permanently to rest. The cilia disappear and the zoospore
assumes a spherical shape, about io-i3ju. in diameter (Plate
XXXI, 14). Some zoospores, instead of rounding up entirely,
assume an amoeboidal appearance, but with scarcely any per-
ceptible movement, and eventually go to pieces without further
development (Plate XXXI, 15). Usually most of the rounded,
resting zoospores soon begin to develop germ tubes, into which
pass their contents. This germ tube is the infection thread by
which the fungus gains entrance to its host. In water it
becomes a simple (rarely branched) regular or irregular thread,
eventually several times the length of the resting zoospore from
which it issues (Plate XXXI, 16). After attaining some length
it gradually becomes empty of contents at its base.
None of the spores observed by the writer germinated directly
through germ tubes, but always through zoospores. Their
germination, however, was tried only in water. Possibly had
some nutrient solution been used, the germination would have
been by germ tubes, as the potato blight spores, which ordinarily
in water germinate through zoospores, in nutrient solutions will
produce germ threads instead. Zimmermann (65), however,,
describes and figures the germination of his var. atra with
germ threads, and Rostowzew (40) with his variety Tweriensis
states that the germination is either by germ threads or zoo-
spores. The germ threads proceed from the spores, usually
from some other point than the papilla of dehiscence. Both
these authors note the papilla of dehiscence, and as this is char-
acteristic of germination by zoospores this may be considered
the typical method.
340 CONNECTICUT EXPERIMENT STATION REPORT, I904.
Infection of Host. In moist summer weather the melon and
cucumber leaves are often covered with small drops of water.
During a cloudy day these may remain on them all day. This
moisture offers a means for the germination of the spores pro-
duced on these leaves or carried there, and thus an infection of
the tissues. The germ tubes of the resting zoospores, or of
the spores when these germinate by germ threads, bore directly
through the epidermis or push their way between the guard cells
of the stomate into the interior of the leaf. (See Plate XXXI,
17-20.) Infection can take place through either the upper
or lower surfaces of the leaves. Spores produced on the
cucumber can infect leaves of the musk melon, as shown by an
experiment by the writer, and no doubt the reverse is true.
Once inside the leaf the infection thread develops the mycelium
and from this soon arise the conidiophores to the exterior.
The extent of infection depends largely on weather condi-
tions. If moist for some time after the fungus gains entrance
to its host, this is favorable for the development of numerous
conidiophores and spores and for the germination of the latter.
During ordinary dry weather the conidiophores are not produced
very abundantly and the spores soon lose their power to
germinate. The effect of moisture on the production of
conidiophores and spores was well illustrated in the infection
experiments carried on in the laborator3^ Usually two or three
days after placing the spores in water on the leaves small dis-
colored spots could be seen at these places, showing successful
infection. If the plants were then left exposed to the ordinary
dry air of the room, very few or no conidiophores were devel-
oped, though the diseased spot often slowly developed in the
leaf. But if the leaves were sprayed with water and the moist
plants covered with a bell jar to preserve a moist atmosphere,
there resulted an evident increase of conidiophores, often by the
next day. The following are short descriptions of two of these
indoor infection experiments.
Experiment 1769-70. September 20 placed spores from
cucumber in drop of water on upper side (1769) of each
cotyledon of five seedling cucumbers and on lower side (1770)
of four seedlings; seedlings in crocks under bell jars. Sep-
tember 22, two cotyledons of 1770 plainly, and one faintly
showing small sunken and discolored spots; bell jars removed.
LIFE HISTORY OF MELON BLIGHT. 34I
September 23, eight of the ten cotyledons of 1769 and five of
the eight of 1770 showing discolored spots; replaced bell jar
over those of 1770 after spraying the seedlings with water.
September 29, conidiophores and conidia on one cotyledon of
1770 but none on 1769. This experiment was in the laboratory
room, which was not adapted for the plants.
Experiment 1771-72. September 26, used cucumber seed-
lings having two cotyledons and one leaf each ; on the upper
surface (1771) of one of the cotyledons and the leaf of each of
seven seedlings placed spores from cucumbers in drop of water
and on the upper surface (1772) of both cotyledons and the
leaf of seven other seedlings placed small fragment of cucumber
leaf containing spores ; sprayed plants with water and left in
greenhouse, as day was cloudy and moisture from leaves did
not evaporate. September 29, only one or two leaves of 1772
showed slight discoloration. October i, six cotyledons and two
leaves of 1771 showed slight yellowish discoloration where
spores were placed; 1772 showed several cotyledons with dis-
colorations. October 15, 1771 showed six of the seven coty-
ledons and five of the seven leaves infected, infected areas dead,
but no luxuriant growth of conidiophores, as atmosphere of
greenhouse was dry; 1772 showed every cotyledon and five of
the seven leaves infected ; the cotyledons were almost dead at
this time and the dead areas on the leaves were more prominent
than in 1771. Conidia and conidiophores, however, were not
abundant, so sprayed 1772 with water and placed under bell
jar over night and the next morning there was an abundance of
new conidiophores developed at the margin of the dead areas.
Winter Spores. The spores that have been described so far
are thin-walled, temporary bodies that cannot survive over win-
ter and are never produced saprophytically. The hosts, too, are
annuals, and for this reason the mycelium cannot be perpetuated
from year to year in perennial parts, as is the mycelium of the
potato mildew (blight) in the tubers. Both these mildews, how-
ever, belong to the family Peronosporaceae and it is character-
istic of this family to produce, besides the summer spores, large,
thick-walled resting spores, or winter spores, that are formed
within the infected tissues and often liberated only on their
decay. Through the germination of those spores the next
season their hosts are infected anew. These winter, or
27
342 CONNECTICUT EXPERIMENT STATION REPORT, I904.
oospores, have been looked for on the melon, cucumber, etc.,
by a number of botanists, but have never been reported, except
by Rostowzew (40). He claims to have found half-matured
oospores in cucumber leaves infected with this mildew, and he
gives a figure and description of them. He states that appar-
ently they do not 'mature until the leaves have rotted in the
ground, and so are largely saprophytic in their development.
There is some question if what this writer saw really had any
connection with this fungus, as often other fungi develop quite
early in the dead spots of the leaves killed by the mildew. It
is not impossible that the oospores develop only as a sapro-
phyte rather than as a parasite, as is usual with this stage. There
is need, however, of more evidence to show the nature and
identity of the immature spores Rostowzew describes before they
can be accepted or rejected as being connected with this mildew.
The writer has made a special effort to discover oospores of the
fungus on its recognized hosts in this state. All parts of the
hosts, under all conditions of infection and decay and at differ-
ent times of the year, have been examined, but nothing was
found that suggested that the fungus develops such a stage
either as a parasite or a saprophyte. So far there has been
obtained no evidence that the fungus, in the United States,
carries itself over the winter in this way. That such a stage
may develop under certain conditions* or in certain regions or
on certain hosts is entirely possible. Rostowzew seems to have
had some further evidence of this stage, or some other stage,
developing in old leaves in the ground, since he obtained earth
from the infected region in Russia and using this on beds
planted with cucumbers, finally developed the disease, while a
check bed having none of this infected soil on it did not.
Before seeing the experiments of Rostowzew, the writer
thought that possibly the fungus might be carried in the soil
containing the remains of diseased plants, and conducted a
couple of experiments to determine this. In the first experi-
ments, in the fall of 1902, dead leaves from infected vines were
mixed with new earth in crocks and planted with cucumbers ;
also old soil in which diseased plants had grown was placed in
* It is barely possible that the oospores are produced only on the
union of distinct or sexual mycelial strains that do not commonly occur
tosrether.
LIFE HISTORY OF MELON BLIGHT. 343
crocks and planted with cucumbers. These were kept in the
greenhouse and the plants did not grow very luxuriantly, but
though they lived two months no signs of the mildew appeared.
In the second case musk melons were planted in a greenhouse
bed in the winter, and after they were up, soil gathered the
middle of February from ground that had badly diseased melons
in it the fall before was placed around the plants, which were
also sprayed with water drained through this soil. Other
plants had the disintegrated remains of infected leaves placed
on the soil and were sprayed with water drained through the
leaves. No mildew showed on these plants two weeks after
this treatment, but further observation was prevented by sick-
ness. These experiments, while not necessarily contradicting
Rostowzew's results, unfortunately do not confirm them.
If, then, the fungus in Connecticut is not carried over the
winter by summer spores or mycelium, and if, as it appears, the
oospores also are not developed here, how does it manage to be
perpetuated? Two possible ways have been suggested, both of
which may be of service. First, it is quite possible that the
fungus in some places is carried over winter by cucumbers, etc.,
raised in greenhouses and later in hot-beds, finally spreading to
the outdoor plants in the summer. A good many early reports
of this fungus were of its occurrence upon greenhouse cucum-
bers, so that its occurrence there is not uncommon. The writer
has found it on the English and market cucumbers in green-
houses late in the fall, and one year found the first observed
infection of the summer on melons started originally in a
greenhouse where cucumbers were usually grown in the winter.
Second, the fungus may carry over winter in the south on hosts
that grow outdoors the year around. Hume (27) states that
this is true in Florida. The fungus in this case would have to
advance northward with the season, and its appearance, no
doubt, would be greatly influenced by the character of the
weather each year. This would account for the variableness
with which it appears and disappears. Selby, of Ohio, who has
been especially interested in the study of this trouble, strongly
supports this theory.
Effect of Season. As stated before, the downy mildew
develops most vigorously when there is a very moist and cold
season, especially during July and August. The cold is per-
344 CONNECTICUT EXPERIMENT STATION REPORT, I904.
haps not so favorable for the development of the fungus, but
when the seasons are unusually moist they are apt to be cool as
a consequence. Periods of foggy or damp, cloudy weather,
with perhaps not much rain, offer better opportunities for the
development of the disease than violent rain storms followed by
clear weather. Aside from any injury from the fungus, a cold,
wet season, in itself, is just the opposite of what musk melons
need in this state for their best development. For instance, the
failure of musk melons in 1903 was as much due to the unfavor-
able season for growth as it was to injury by fungi. The cold,
damp weather retarded the growth of the vines so that they
were very late in coming into bearing, and this, coupled with
fungous attacks, made the crop a failure. The development of
the cucumber is not influenced so much as the musk melon by
weather conditions.
Injury to Hosts. The mildew is one of the most injurious
pests of the cucurbits. Ordinarily the cucumber and musk
melon have suffered most, though the squash and watermelon
have been reported as seriously injured. Halsted (17) reported
that Sturgis found watermelons in this state severely injured,
but Sturgis made no statement of such injury in the Reports of
the Station. The writer has found the fungus only a few times
on this host, and then doing no serious injury. These speci-
mens showed a few dead areas on the leaves, but no external
evidence of the fungus, whose presence was established only
by microscopic examination. On the cucumber the fungus
developed much more aggressively. There was a greenish
yellow spotting of the leaves on their upper surface, while
beneath usually could be seen a growth of the conidiophores,
whose purple black spores became quite conspicuous under a
hand lens. Later the leaves often became more conspicuously
spotted or withered away, new growth ceased to take place and
the plants finally died. With the musk melon the trouble
seemed to be most severe, as the yellowish spots soon changed
into dead reddish brown areas, with the resultant death of the
intervening tissues and withering of the leaves. With weather
favorable for the spread of the disease, the vines very quickly
succumbed. The growth of the fungus on the under side of
the leaves of the musk melon was not usually so evident as on
the cucumber and became most pronounced at the border of the
LIFE HISTORY OF MELON BLIGHT. 345
dead areas. Even when the vines were not killed outrig-ht they
rarely matured their fruit, or if some of the melons ripened they
always lacked the requisite flavor. (See Plates XXIX, XXX.)
Financial Loss. It is difficult to estimate the financial loss
caused by any disease. In this state the injury, due chiefly to
this fungus, and partially to other fungi and unfavorable weather
for growth, was so great during the years 1901, 1902, 1903
that the area devoted to musk melons was gradually cut down
until it reached almost a zero limit in 1904, which year proving
a fairly favorable season, no doubt the acreage will gradually
go back to the maximum. In 1901, and especially in 1902, the
fungus practically destroyed the melon fields in a few days.
The loss from injury to cucumbers in this state, while possibly
equalling that of the melons, was not so evident. These plants
often lag along under the disease and give a partial crop, espe-
cially the early plantings, and the flavor of the fruit is not an
important question. Late cucumbers grown for pickles, how-
ever, suffer worse than the early, since the disease is often at its
height when these are just starting, and the vines are usually
killed before any fruit is obtained. Raising pickling cucumbers
for the factories is not an important industry in this state, and
so the loss here has been very much less than on Long Island
and in Ohio.
Conftision with other Diseases. There are a number of other
diseases of the cucurbits that have been in part responsible for
the injury of these hosts. It is not always possible for one not
well acquainted with these to distinguish them from the downy
mildew. With this the most distinguishing macroscopic char-
acter is the growth of the fungus on the under surface of the
spots, especially at the margins, the purplish black spores on the
conidiophores becoming quite evident when a hand lens is used.
The distinguishing characters of the other troubles as deter-
mined by the naked eye or a hand lens are as follows :
Scab, Cladosporium cucumerinum, occurs on the leaves, stems
and fruit, producing sunken areas on the latter two, and the
dead spots become covered with a more or less evident olive,
moldy fungous growth.
Leaf Spot, Alternaria Brassicae var. nigrescens, usually forms
roundish, dead, reddish brown spots on the leaves ; these spots
often show faint concentric rings of development, but no evi-
346 CONNECTICUT EXPERIMENT STATION REPORT, I904.
dent fungous growth. This sometimes becomes a serious
trouble, considerably resembling the downy mildew in its
ultimate effect and appearance.
Anthracnose, Colletotrichnm Lagenarium, is a common and
widespread trouble present more or less each season. It is most
conspicuous on the ripening fruit, but this is often attacked
while quite green, showing sunken, rotten areas that are usually
covered with pinkish, often sticky, exudations of spores. The
minute spore exudations on the leaves are easily washed off by
rain, and the reddish brown spots are very similar to those of
the leaf spot, but angular and often more extended.
Bacterial Wilt, Bacillus tracheiphilus Sm., often wilts down
the whole vine without any spotting of the leaves, which merely
dry up on their petioles. Sometimes, however, there appear
distinct, often semi-pellucid, areas in the leaves. In the former
case the bacteria merely clog the water ducts and cut off the
supply of water from the leaves, which then wither and die,
while in the latter case the bacteria also cause disease of the
leaf tissues. A soft bacterial rot of the fruit, apparently, is
sometimes connected with this trouble.
Prevention.
Cucumber. So destructive has the downy mildew proved to
cucumbers grown in the eastern United States that a number
of experiment stations have made experiments to determine if
it could be controlled. Practically all of the experimental work
has been done by spraying with Bordeaux mixture, the chief
points of interest being to determine if the disease could be con-
trolled, when and how often it was necessary to spray, and if
spraying could be done on a paying basis.
Halsted (20) of New Jersey was the first to report spraying
experiments against this trouble, conducted in 1895. He wrote
in part as follows : "Spraying with Bordeaux gave very favor-
able results in the cucumber belts so treated. Two fungi
peculiar to the cucumber, namely, the mildew (Plasmopara
Cubensis B. & C.) and anthracnose {Collet otrichum Lagena-
rium Pass.), were sufficiently abundant to do serious injury.
. . . By August 20 the combined attack of fungi and insects
resulted in the destruction of most of the vines in all of the belts
PREVENTION OF MELON BLIGHT. 34/
except in the two sprayed with Bordeaux. ... As a result
the Bordeaux vines were green and vigorous for over a month
after those in the adjoining belts were dead. The yield of
fruits was considerably increased and the percentage of fruit-
rot greatly diminished."
The next year Stewart (53) of New York carried on experi-
ments on Long Island to prevent this trouble on late or pickling
cucumbers, which were being severely injured in that region.
He says in his report of these experiments : "The downy mildew
first appeared on the unsprayed plants August 7, and by August
21 it had injured the foliage to such an extent that scarcely any
cucumbers were produced after this date. The thirty-two rows
of plants which had been sprayed were in perfect health and
vigor on August 21, and after this date produced two hundred
and sixty dollars worth of cucumbers, which represents approxi-
mately the benefit resulting from spraying." In 1897 and in
1898 Stewart and Sirrine carried on other successful spraying
experiments, both with early and late cucumbers. These experi-
ments were conducted on a large scale and gave satisfactory
financial results.
Selby (44) of Ohio, in 1897, also conducted successful spray-
ing experiments on late or pickling cucumbers. He makes the
following statement: "For Wayne County, Ohio, this fungus
disease has caused in 1897 a loss of about GGYs per cent, of the
crop. Computed at an average of about 210 bushels per acre,
and one-third large pickles, this loss at factory prices reaches
almost $45,000 for the single season in Wayne County. . . .
These two diseases (mildew and anthracnose) may be very
largely, if not entirely, suppressed by spraying about seven times
with Bordeaux mixture, making the first application as the
plants begin to vine and keeping the leaves covered with the
fungicide thereafter, until about September 10. The cost for
these sprayings need not exceed $10 per acre, and may be
reduced to $7.50."
Since these earlier and most extensive experiments several
other investigators have reported more or less successful experi-
ments. With those conducted by the writer, chiefly against the
mildew on the musk melon, one row of cucumbers was also
sprayed, and the results obtained in this case were sufficient to
show that ordinarily the mildew, anthracnose, leaf spot and scab
348 CONNECTICUT EXPERIMENT STATION REPORT, I904.
could be controlled on this host by spraying a sufficient number
of times with Bordeaux, and that when these troubles were bad
such treatment was a paying venture. The bacterial wilt, how-
ever, seemed to be as bad on the sprayed as on the unsprayed
vines.
The consensus of opinion, then, seems to be favorable for
spraying cucumbers, especially late cucumbers raised for
pickling, when suffering from mildew, anthracnose, etc. Of
course, in the years when these fungous troubles are not
injurious spraying would not pay for itself. Bordeaux mixture
(four pounds copper sulphate, four pounds lime and forty to
forty-five gallons water) is the best fungicide for this purpose.
The spraying should begin about July 5 to 15, according to the
season, but the first application should always precede rather
than follow the first appearance of the disease. From five to
seven sprayings are necessary to keep the foliage well covered
with the fungicide until the first part of September. Where an
acre or less of cucumbers are grown the small barrel pump
mounted on two wheels and dragged by hand is a very con-
venient outfit. The vines can be trained about every fifty feet
so that a path of sufficient width for the cart can be kept open.
From this the vines on each side can be sprayed by using a
twenty-foot hose, one man pumping and pulling the cart and
another spraying the vines. Where more than an acre of
cucumbers are grown it is advisable to leave roadways (perhaps
planted with some early maturing crop), and from these the
vines can be sprayed from a barrel pump carried in a light
wagon. Before each spraying the ripe cucumbers should be
picked, otherwise no attention need be paid about the spray
getting on the fruit.
Musk melons: experiments elsewhere. The spraying experi-
ments against this trouble on the musk melon are not nearly so
favorable as those on the cucumber. In fact, when the mildew
is severe it is doubtful if any good results, and even taken year
in and year out very little will be gained if the failures are
counted in. This does not mean that good does not result some-
times from spraying, as regards moderate attacks and especially
with anthracnose, leaf spot or scab, which are more easily con-
trolled, but in general the results do not warrant the extra cost
and trouble of spraying.
PREVENTION OF MELON BLIGHT. 349
Selby (46) of Ohio was one of the first to report spraying
experiments, made in 1898, against the mildew on musk melons.
His experiments were not so extensive with the musk melon
as with the cucumber, and while favorable results were reported
in one case, he states : "On the whole, we cannot conclude that
the use of Bordeaux mixture for the fungus parasites of the
musk melon has proven a decided success."
Lamson (33) reports that spraying experiments in 1901 made
on garden musk melons after the mildew appeared gave little,
if any, good results, while in 1902 (34) treatments started
earlier and repeated five times kept the musk melons alive two
or three weeks later than those not sprayed.
Stone and Smith, in the 15th Ann. Rept. of Mass., write as
follows: "The subject of spraying as a preventive for this
trouble has received considerable attention from this division
for several years. During the past season [1902] experiments
were made in cooperation with a local grower along the lines
which previous experience had suggested. The details of this
work will be reserved for a bulletin ; but it may be said here
that, even where plants were thoroughly sprayed with Bordeaux
mixture, commencing early in July when the first leaves devel-
oped, no effect could be seen upon the development of the
mildew, sprayed and unsprayed plots and fields were alike a
complete failure."
Bennett (i) of Storrs Station, this state, reports spraying
experiments in 1903, as follows : "Three plots of musk melons
were planted, two of which were sprayed, the third being left
unsprayed. Owing to the cold season none of the melons
matured fruits. The result of the spraying was practically the
same with the melons as with the cucumbers. Traces of blight
could be seen on the sprayed foliage, but they were not suf-
ficiently abundant to do any harm. The unsprayed plants
succumbed to the disease even before the cucumbers did."
Musk melons: experiments in Connecticut. During the three
seasons 1902, 1903, 1904, the writer conducted a number of
experiments to determine how efficient and practical spraying
was in preventing the downy mildew and other fungous troubles
of the musk melon. Each year presented weather conditions
somewhat different, varying from exceedingly favorable to
unfavorable for the development of the mildew. From the
350 CONNECTICUT EXPERIMENT STATION REPORT, I904.
results of these experiments, coupled with the experience of
others, we have come to the conclusion that spraying musk
melons with Bordeaux as a yearly practice will give no better
average financial results than where no spraying is practiced.
There are probably seasons when spraying would pay, if these
could be foretold, but again there are seasons when it will be
money thrown away. The results of these experiments are as
follows :
In ig02 the mildew, which evidently had been very injurious
to musk melons the year before, was first found in New Haven
in a private garden about the middle of July. From then on to
the first of August it appeared on practically all of the cucum-
bers and musk melons raised in this vicinity. With the musk
melons the injury was sudden and severe, so that all of the
vines were dead before any fruit ripened thoroughly. This was
a cold, wet year, especially in July, which was unusually cold
and foggy.
1. July 19 the writer examined three small patches of musk
melons in the garden of Mr. Sperry, New Haven, and found
the first outbreak of the mildew observed this year. The plants
of the oldest patch had been started in the greenhouses, to mature
them earlier, and these showed the disease rather badly, while
the two younger patches were not yet visibly infected. Upon
the advice of the writer, the gardener sprayed these younger
vines a few days later. August 2 visited the garden again
and found this spraying had not prevented the appearance of
the disease on these melons, which were now in about the con-
dition of the older melons when first seen. Numerous rains,
however, had washed off all the spray. The vines soon died,
with no melons matured.
2. M. W. Frisbie & Son, of Southington, on July 28, sprayed
part of their commercial field at the writer's suggestion. At
this time no mildew was seen in the field, though some bacterial
wilt was present. When examined again, August 8, a few
leaves showed the presence of the mildew. It was intended by
the writer that other sprayings should be given, but wet weather
prevented at the proper time, and then the owners were afraid
the spray might injure the appearance of the fruit. No good
resulted from this single treatment and the crop was a failure.
3. August 4 the writer sprayed a row of melons in each of
two fields on the farm of Mr, Nesbit in Hamden. At this time
PREVENTION OF MELON BLIGHT. 351
the mildew was just beginning to appear scattered through the
fields, though a week previous the anthracnose and bacterial wilt
had been noticed in spots. August 9 examined the field and
found the mildew spreading rapidly, with little difference
between sprayed and unsprayed plants. August 13 one of these
fields was pulled up, as both sprayed and unsprayed plants were
beyond recovery. Sprayed the second field again on this date,
but expected little or no good to result, as plants were severely
injured. This field also was soon pulled up, as no melons were
expected from either sprayed or unsprayed plants.
4. August 5, a little mildew was first seen on a few melons
grown on the Experiment Station grounds, and on August 7
a part of these were very thoroughly sprayed with Bordeaux
mixture. A few vines were sprayed above and then turned
over and sprayed on their under surface. On August 20 the
vines were sprayed thoroughly again. The mildew carried off
the unsprayed vines finally. Those thoroughly sprayed on both
surfaces did not develop the mildew much further, but they
failed to make sufficient new growth to mature their fruit.
Plate XXX, b, shows the condition of sprayed and unsprayed
vines on August 30.
5. August 23, sprayed the greater part of a small patch of
musk melons in the garden of Mr. Hartley at Centreville. The
blight had rather severely injured these, but the spraying was
made to see if its advance could be checked and the melons
recover by new growth. September 2, examined the patch
again, but as no beneficial results of the spraying could be seen
no further treatments were given. No melons matured.
It will be noticed that most of these experiments were started
after the appearance of the mildew on the vines. This was
because the writer did not take up his work at the Station until
July and so did not know what to expect from this trouble. It
was thought desirable, however, to make these tardy treatments
to see if the disease could be checked and a partial crop obtained.
The experiments show that this certainly cannot be done when
the disease is at all serious and the season unfavorable for the
growth of the vines. However, it is quite certain that very few
or no melons would have been obtained even had the spraying
■ been started early and applied thoroughly through the season, as
the following reports from Connecticut growers for this year
show :
352 CONNECTICUT EXPERIMENT STATION REPORT, I9O4.
6. Mr. J. C. Eddy of Simsbury sprayed melons five times,
twice in the greenhouse before transplanting. These vines were
somewhat better than those not sprayed, but still "blighted"
and produced no marketable fruit.
7. Mr. J. S. Eddy of Unionville thoroughly sprayed his
melons, but they did not amount to anything. When examined
by the writer on August 26 no mildew was found, but there was
a small amount of leaf spot. The cold, damp season, appar-
ently, was chiefly responsible for their feeble growth, which the
owner described as "hide bound." The crop was a failure.
8. Mr. C. B. Meeker of Westport sprayed his melons six or
seven times, beginning as soon as the vines started to run. He
got no results from his spraying.
9. Mr. E. M. Ives of Meriden sprayed a few melons in his
garden. He sprayed both sides of the leaves, turning the vines
over to reach the under surface. He reports a few melons for
his trouble.
In ipo^ the growing season was also wet and somewhat cool,
but not so bad as the previous one. The mildew was very much
later in its appearance, being first found in the vicinity of New
Haven September 14. On the whole it did no more damage to
musk melons than did anthracnose, leaf spot, scab or wilt, all
of which were found during the season, sometimes several
occurring together in the same field. Taken altogether, these
various fungus pests perhaps did not do as much injury to the
melons as the cold, wet growing season did in preventing favor-
able growth of the vines. Little or no fruit was gathered from
any of the fields and gardens.
10. A spraying experiment this year was made at the
Experiment Station grounds on musk melons especially planted
for this purpose and carefully watched during the whole season.
A row each of Early Gem, Jenny Lind and Hackensack (also
one of cucumbers) was planted and divided into five equal
plats. These, except the fifth, or check plat, were all sprayed
five times, as follows : July 14, July 28, August 8, August 26,
September 10. The season was late, so that the first spraying
was made on the plants when quite small and with no sign of
any fungous disease on them. Bordeaux mixture was used on
all four plats for the first three treatments, after which plat i
received two treatments with resin Bordeaux, plat 2 two treat-
PREVENTION OF MELON BLIGHT. 353
ments with soda Bordeaux, plat 3 two treatments with potas-
sium sulphide, and plat 4 two treatments with fresno (ammo,
sol. cop. carb.). These other fungicides, except resin Bor-
deaux, were used in the last two sprayings to avoid any sediment
on the fruit when ripe, as some growers seem to be afraid to
spray after the melons begin to ripen.
The conclusions drawn from this experiment are as follows :
(a) The sprayed plats, especially the Bordeaux plat i, gave
the best results in freedom of the foliage from fungi and in size
and vigor of plants and number of young melons started. The
unsprayed plat 5 was the poorest in these respects and
developed considerable anthracnose and scab, and possibly a
little mildew at the very end of the season, (b) The spraying
did no good in preventing the bacterial wilt, as a few plants
were killed in all of the plats and the fruit suffered some from
a soft rot, possibly caused by the same organism. Some of
the earlier sprayings did some slight injury to the leaves, shown
by their turning yellow at the margins and slowly dying,
(d) Resin Bordeaux adheres better than Bordeaux, but is more
expensive and difficult to make, and so will not generally be
used. If any spraying is to be done, everything considered,
Bordeaux mixture is the most desirable fungicide, even for the
late sprayings, as little spray reaches the melons if the ripe
ones are picked before spraying, and no injury or harm can come
from any little sediment that may remain when the fruit is
picked subsequently, (e) The spraying in this experiment did
not pay for itself, since practically no marketable melons were
obtained. The failure of melons on the sprayed vines was
chiefly due to the cold, wet season, which prevented vigorous
growth of foliage.
In ip04 the season was warm and fairly dry during July and
August, so that it was favorable for the growth of the vines,
and also unfavorable for the development of fungous troubles.
No mildew was found by the writer anywhere, except a little
on some garden cucumbers on September lo. So this fungus
did no damage whatever this season ; neither were the other
fungous diseases troublesome, so far as observed, except the
wilt, which did less damage than usual. For the first time in
several years, due chiefly to the warmer, drier growing season,
a fair crop of musk melons was generally obtained throughout
354 CONNECTICUT EXPERIMENT STATION REPORT, I9O4.
the state, though this was shortened somewhat by a kilHng frost
on September 21.
II. A spraying experiment this year was conducted on the
farm of Andrew Ure of Highwood to determine whether spray-
ing with Bordeaux mixture was a desirable and profitable
treatment to advocate to market gardeners for their melons. A
patch of about a quarter of an acre was planted by Mr. Ure for
this purpose and two-thirds of this was thoroughly sprayed four
times. These treatments were made July 6, July 21, August 4
and August 18, and as the season was not very wet the vines
were fairly well coated with the spray during the entire season.
The results may be summarized as follows: (a) No mildew
appeared on either sprayed or unsprayed plants. A little leaf
spot was finally observed on some of the unsprayed plants, but
there was not enough to do any damage. The bacterial wilt
injured and killed a few vines and there was considerable injury
from a soft bacterial rot of the fruit about the time of its
maturity, probably also caused by the wilt organism. (See
Plate XXIII, c.) As shown last season and in this experiment,
spraying was of little or no benefit in preventing the wilt,
(b) Th^ first spraying was really made on all of the vines,
except two rows, but as it looked as if the treatment had caused
some yellowing of the foliage, over one-third of the patch was
left unsprayed thereafter. No evident or permanent injury
resulted from spraying, however. At the end of the season the
sprayed vines looked fully as vigorous, if not a little more so,
than those which were not sprayed. The spraying, then, was
of little or no benefit to the foliage and vines, (c) A fair crop
of melons was gathered from both sprayed and unsprayed vines.
No effort was made to determine the exact number from each,
as it was evident that if any difference existed (and it would
have been small) it would scarcely be due to the spraying.
CONCLUSIONS FROM EXPERIMENTS. Summing up the
results of these three seasons' experiments, ■we conclude : First —
When the dovyny mildew is very severe, as in 1902, spraying musk
melons is useless. Second — When the seasons are cold and damp but
fungi not unusually destructive, spraying may show some benefit to the
foliage, but the unfavorable influence of the weather will not be over-
come by this treatment. Third — Warm, fairly dry seasons (moisture
well distributed) are necessary for the best development of musk melons
■in Connecticut and such seasons are not likely to bring serious attacks
LITERATURE ON MELON BLIGHT. 355
of fungi, so that spraying in these seasons is of little or no advantage.
Fourth — Everything considered, spraying musk melons scarcely merits
recommendation in this state. These statements do not apply to the
cucumber, which host vvithout doubt is often benefited by thorough
spraying.
Literature.
The following references include all the more important
articles and even notes which the writer has found in literature
relating to this mildew. As a natural consequence of the
fungus being found, until recently, chiefly in this country, and
because of its severe injury to cultivated plants, the literature is
largely from our Experiment Station workers.
1. Bennett, E. R. Bordeaux Spraying for Melon Blight. Storrs Agr.
Exp. Stat. Bull. 30:17. 1904.
Reports favorable results from spraying seven times with Bor-
deaux mixture, especially vi^ith the yield and foliage of the cucum-
bers, while with musk melons the foliage was improved.
2. Berkeley and Curtis. Peronospora Cubensis B. & C. Journ.
Linn. Soc. Bot. 10 : 363. 1868.
Describe this new species collected on cucurbitaceous host by
Wright in Cuba.
3. Berlese, A. N. and De Toni, J. B. Peronospora cubensis Berk, et
Curt. Sacc. Syll. Fung. 7:261. 1888.
Give Berkeley's description of this fungus.
4. Berlese, A. N. Plasmopara cubensis (B. et C). Riv. Pat. Veg.
9 : 123-6. 1901. [Illustr.]
Gives botanical description, hosts, distribution and general dis-
cussion of this fungus, for which he creates a new sub-genus,
Peronoplasmopara.
5. Cazzani, E. Sulla comparsa della Peronospora cubensis Berk, et
Curt, in Italia. Centr. Bakt. Par. Infekt. 12 : 744. 1904. [Reprint
from Atti Inst. Bot. Pavia 9 : 14. 1903-4.]
Reports this on melon leaves from Pavia and Rimini, Italy,
in 1903.
6. Clinton, G. P. Report on Fungous Diseases of 1903. Conn. Pom.
Soc, Ann. Vol. 6 : 23. 1904.
States that downy mildew appeared later and did less damage
in Conn, in 1903 than it did the previous year.
7. Clinton, G. P. Downy Mildew (Blight) Plasmopara Cubensis (B.
& C.) Humph. Conn. Agr. Exp. Stat. Rept. 1903:318-19, 330-31,
370. 1904. [Illustr.]
Gives a short account of the fungus, with its hosts and the
injury done in Conn.
8. Cooke, M. C. Cucumber and Melon Rot Mould. Journ. Roy. Hort.
Soc. 27 : 823. 1903.
35^ CONNECTICUT EXPERIMENT STATION REPORT, I904.
Gives short note on this fungus with suggestions for its
prevention.
9. Eckardt, C. H. Ueber die wichtigsten in neuerer Zeit aufgetretenen
Krankheiten der Gurken. Prakt. Blat Pflanzenb. Pflanzensch. 2 :
[Revievi? by Posch, Centr. Bakt. Par. Infek. 13 : 787. 1904.]
Notes injury in Austria from this trouble, and suggests spraying.
ID. Farlow, W. G. Notes on Fungi I. Bot. Gaz. 14 : 189-90. 1889.
Gives a general account of Peronospora Cubensis received from
Japan, and identifies specimens from Halsted of New Jersey,
the latter being the first collection in the United States.
11. Galloway, B. T. New Localities for Peronospora Cubensis B. &
C. Journ. Myc. 5 : 216. 1889.
Reports this from Fla. and Texas, on cucumbers, which suffer
severely from the fungus.
12. Garman, H. Cucumber Mildew. Ky. Agr. Exp. Stat. Bull. 91: 50-1.
1901.
Notes this fungus especially destructive to cucumbers in Ken-
tucky in 1897 and 1898 ; finds conidia larger than described by
Berkeley.
13. Halsted, B. D. Peronospora upon cucumbers. Bot. Gaz. 14 : 152-3.
1889.
Notes appearance of an unidentified Peronospora (see Farlow)
on greenhouse cucumbers in May, 1889, at New Brunswick, N. J.
This is the first collection of the mildew in the United States.
14. Halsted, B. D. Some Notes upon Economic Peronosporeae for
1899 in New Jersey. Journ. Myc. 5 : 201-2. 1889.
Reports this later very abundant and injurious outdoors upon
squash, pumpkin and cucumbers.
15. Halsted, B. D. Notes upon Peronosporae for 1890. Bot. Gaz.
15 : 322. 1890.
Notes the absence of cucumber mildew this year in N. J.
16. Halsted, B. D. Notes upon Peronosporeae for 1891. Bot. Gaz.
16:339. 1891.
Notes prevalence of Peronospora Cubensis B. & C. in 1891 ;
lists from N. J., Dist. Col., and Conn, (on watermelon).
17. Halsted, B. D. Peronospora Cubensis B. & C. (Cucumber Mil-
dew). N. J. Agr. Exp. Stat. Rept. 12:248. 1892.
Notes prevalence of this fungus in 1891 in N. J. and elsewhere ;
states Sturgis found it in Conn, on watermelon.
18. Halsted, B. D. Fungous Diseases of the Muskmelon. N. J. Agr.
Exp. Stat. Rept. 14:352-3. 1894. [Illustr.]
Briefly describes damage done by downy mildew.
19. Halsted, B. D. The Downy Mildew (Plastnopara Cubensis B. &
C). N. J. Agr. Exp. Stat. Rept. 15:348, 350, 359- i895-
Lists on cucumbers, musk melons and squash from N. J.
20. Halsted, B. D. Bordeaux with Cucumbers. N. J. Agr. Exp. Stat.
Rept. 16: 327. 1896.
LITERATURE ON MELON BLIGHT. 357
Notes favorable results from spraying against downy mildew,
etc., since the sprayed plants lived one month longer than those
not sprayed.
21. Halsted, B. D. Experiments with Cucumbers. N. J. Agr. Exp.
Stat. Rept. 17 : 340-44. 1897.
Sprayed plants with Bordeaux, soda Bordeaux, potash Bordeaux,
but results of little importance in determining value in preventing
downy mildew, as this was not present.
22. Halsted, B. D. Experiments with Cucumbers. N. J. Agr. Exp.
Stat. Rept. 18: 319-22. 1898.
Reports Bordeaux and potash Bordeaux as useful in preventing
the downy mildew.
23. Halsted, B. D. The Blight of Cucumbers. N. J. Agr. Exp. Stat.
Rept. 22 : 437, 440. 1902.
Notes that this was common in N. J. in 1901, and destroyed most
of the musk melons ; a plot of cucumbers was kept in full leaf
and vigor by spraying with soda Bordeaux.
24. Hecke, L. Ueber das Auftreten von Plasmopara cubensis in Oster-
reich. Ann. Myc. 2 : 355-8. 1904.
Reports the mildew from Vienna, Austria, on cucumbers ; gives
historical and botanical account of fungus.
25. Hecke, L. Ueber das Auftreten von Plasmopara cubensis in Oster-
reich. Zeit. Landw. Ver. Oester. 1904. [Review, Bot. Centr.
95 : 640-41. 1904-]
Notes presence in Austria on cucumbers ; gives distribution,
history, etc.
26. Hennings, P. Fungi S. Paulenses I. Hedw. 41 : 104. 1902.
Lists Peronospora cubensis B. et C. on Cucumis sativus from
Sao Paulo, S. Amer., collected in 1900.
27. Hume, H. H. Downy Mildew of the Cucumber. Ann. Rept. Fla.
Agr. Exp. Stat. 12-13 '■ 3°- IQOO-
Reports this serious in Fla. on cucumber; states that it lives
there throughout the year ; gives short botanical and historical
account of fungus, and reports successful spraying experiments by
a grower.
28. Humphrey, J. E. The . Cucumber Mildew. — Plasmopara Cubensis
(B. & C.) Humph. Ann. Rept. Mass. Agr. Exp. Stat. 1890:210-2.
1891. [Illustr.]
Notes injury in Mass. to cucumbers and squash by Peronospora
Cubensis B. & C, which he here places under the genus Plas-
mopara; notes structure and germination of fungus.
29. Humphrey, J. E. The Downy Mildew. — Plasmopara Cubensis (B.
& C.) Humph. Dept. Veg. Path. Mass. St. Exp. Stat. 1902:
1S-19.
Notes its injury to cucumbers grown in greenhouse.
30. Jaczewski, A. de. Note sur le Peronospora cubensis B. et C. Rev.
Myc. 22 : 45-7. 1900. [Illustr.]
28
358 CONNECTICUT EXPERIMENT STATION REPORT, I904.
Reports Plasinopara australis on Scliizopepo hryoniacfolius col-
lected in Manchuria in 1876 [not P. Cubcnsis as reported by
Hecke] ; calls attention to differences between these two mildews,
and gives scientific description of P. Cubensis, but makes mistake
in calling conidia hyaline.
31. Jaczewski, A. de. Plasinopara Cubensis. Bull. Torr. Bot. Club
29 : 649. 1902.
Notes presence of this fungus in Russia.
32. Kornauth, K. Ueber in Jahre 1903 beobachtete Pflanzenkrankheiten.
Zeitschr Landw. Vers. Oester. 1904:159. [Review, Centr. Bakt.
Par. Infek. 13 : 461.]
Notes presence of Peronospora Cubensis on cucurbitaceous plant
in Vienna greenhouse.
33. Lamson, H. H. Downy Mildew of the Cucuinber and Musk Melon.
N. Hamp. Agr. Exp. Stat. Bull. 87: 129. 1901.
Notes this fungus injurious to cucumbers and musk melons in
N. Hamp. ; spraying experiments, begun after appearance of the
disease, did no good.
34. Lamson, H. H. Fungous Diseases and Spraying. N. Hamp. Agr.
Exp. Stat. Bull. loi : 63, 64. 1903.
Reports favorable results from spraying cucumbers and musk
melons with Bordeaux beginning about the middle of July; applied
five times at intervals of about 10 days.
35. Linhart. Die Peronospora-recte Pseudoperonospora Krankheit der
Melon und Gurken in Ungarn. Zeits. Pflanzenk. 14: 143-45. I904-
Reports severe outbreak of downy mildew on cucumbers, musk
and watermelons in Hungary in 1903.
36. Massee, G. Cucumber and Melon Mildew. A Text Book of Plant
Diseases : 80. 1899.
Notes its recent introduction into England, on Cucurbita pepo
and Cticuniis saliva, from Japan.
27. Orton, W. A. Plant Diseases in the United States in 1901. Year-
book U. S. Dept. Agr. 1901 : 670. 1902.
Notes downy mildew did damage to musk melons in Long Island,
N. Y., Mass., Conn., N. J.
38. Orton, W. A. Plant Diseases in the United States in 1902. Year-
book U. S. Dept. Agr. 1902 : 717. 1903.
Reports downy mildew injurious to cucumbers and musk melons
in southern New England.
39. Orton, W. A. Plant Diseases in 1903. Year Book U. S. Dept. Agr.
1903 : 553- 1904-
Reports downy mildew causing large loss of cucumbers in
Florida and S. Car. ; also destructive in West Virg., Penn., N. Y.
and Mich. ; occurred in Ohio, Mass., Conn., R. I.
40. Rostowzew, S. J. Beitrage zur Kenntnis der Peronosporeen. Flora
92:405-30. 1903. [Illustr.]
Describes a new var., Tweriensis, of the downy mildew, from
the province Twer, Russia; places this and the species under a
new genus, Pseudoperonospora; gives detailed botanical account
LITERATURE ON MELON BLIGHT. 359
of the mildew; describes immature oospores; gives experiments
with infected soil, etc.
41. Saccardo, D. Plaswopara Cubensis (B. & C.) Humphrey. Myc.
Ital. 1276.
Issues specimens from Italy and states conidia are 22-25 by
15-17M hyaline, finally olive brown, and not violet, as reported by
Humphrey.
42. Saccardo, P. A. Notae mycologicae. Ann. Myc. 2 : 14. 1904.
Notes mildew was found on Cucuinis Melo at Selva (Treviso),
Italy, in 1903.
43. Selby, A. D. Downy Mildew of Cucumbers. Ohio Agr. Exp. Stat.
Bull. 72, : 234. 1897.
Notes prevalence in Ohio on cucumbers in greenhouses and also
outdoors.
44. Selby, A. D. Cucumber Diseases. Ohio Agr. Exp. Stat. Bull.
89:99-116. 1897.
Notes very injurious effect of downy mildew on late or pickling
cucumbers in Ohio, especially in 1897; gives botanical account of
fungus ; records successful spraying experiments with Bordeaux.
45. Selby, A. D. Studies of the Diseases of Cucurbits and Tomatoes.
Ohio Agr. Exp. Stat. Bull, in: 140-41. 1899.
Refers to work done by Ohio Station in study and prevention of
downy mildew of cucumbers, etc.
46. Selby, A, D. Further Studies of Cucumber, Melon and Tomato
Diseases, with Experiments. Ohio Agr. Exp. Stat. Bull. 105 : 219-
21, 223-29, 230-1. 1899.
Gives notes on downy mildew ; also list of hosts upon which it
spread in the disease garden ; gives successful spraying experi-
ments with Bordeaux on cucumbers, and chiefly unsuccessful ones
on musk melon.
47. Selby, A. D. Additional Host Plants of Plasniopara cubensis. Bot.
Gaz. 27 : 67-8. 1899.
Grew a large number of cucurbits in a disease garden on most
of which the mildew spread from the ordinary hosts. (See hosts
elsewhere in this article.)
48. Selby, A. D. Certain troublesome Diseases of Tomatoes and Cu-
curbits. Reprint Journ. Columbus Hort. Soc. 11: i.
Notes downy mildew becoming common in Ohio, especially in
greenhouses.
49. Selby, A. D. A Condensed Handbook of the Diseases of the Culti-
vated Plants in Ohio. Ohio Agr. Exp. Stat. Bull. 121 : 29, 33, 38,
SI, 54, 58. 1900.
Gives short notes on downy mildew under the following hosts :
cucumber, gourd, musk melon, pumpkin, squash and watermelon.
so. Selby, A. D. Calendar for Treatment of Plant Diseases and Insect
Pests. Ohio Agr. Exp. Stat. Bull. 147: 50, SI. 1904.
Recommends for downy mildew of cucumber and musk melon
at least four sprayings with Bordeaux, at intervals of eight to ten
days, beginning about the time the vines start to run.
360 CONNECTICUT EXPERIMENT STATION REPORT, I9O4.
51. Sirrine, F. A. and Stewart, F. C. Spraying Cucumbers in the
Season of 1898. N. Y. Agr. Exp. Stat. Bull. 156:376-96. 1898.
Give very favorable results of several spraying experiments with
Bordeaux made on a large scale with pickling cucumbers ; recom-
mend first treatment July 15 to August i, repeating every eight to
ten days until frost; give cost of spraying, yields and profits in
their experiments.
52. Stene, A. E. When to Spray. R. I. Agr. Exp. Stat. Bull. 100: 127.
1904.
Notes downy mildew difficult to control, recommends Bordeaux
beginning middle of July and repeating every ten to twelve days
during season of vines.
53. Stewart, F. C. The Downy Mildew of the Cucumber; what it is
and how to prevent it. N. Y. Agr. Exp. Stat. Bull. 119: 155-82.
J897. [Illustr.]
Gives general and botanical account of this fungus, which was
serious in New York in 1896; reports very successful spraying
experiments with Bordeaux on late cucumbers ; recommends
spraying the young plants and repeating every eight to ten days
till frost.
54. Stewart, F. C. Further Experiments on Spraying Cucumbers.
N. Y. Agr. Exp. Stat. Bull. 138 : 636-44. 1897.
Gives favorable results from spraying early cucumbers with
Bordeaux (i to 8 formula) to prevent downy mildew in 1897;
notes impractical results of trying to prevent mildew by shad-
ing with corn ; reports new host, Cucumis moschata.
55. Stone, G. E. and Smith, R. E. Cucumber Mildew (Plasmopara
Cubensis B. & C). Mass. Agr. Exp. Stat. Rept. 13:72-3. 1901.
Note appearance on greenhouse cucumbers in Mass.
56. Stone, G. E. and Smith, R. E. Melon Failures. Mass. Agr. Exp.
Stat. Rept. 14 : 62-6. 1902.
Report downy mildew with Alternaria and CoUetotrichum, the
cause of unusual failure of musk melons ; also bad on cucumbers ;
spraying not entirely effective with musk melon, but advocated.
57. Stone, G. E. and Smith, R. E. Report of the Botanists. Mass.
Agr. Exp. Stat. Rept. 15 : 28, 29-32, 37-8. 1903.
Give general notes on prevalence of downy mildew on cucumber
and musk melon in Mass. ; note growth of plants under tents ;
think mildew can be kept off from plants grown in greenhouse
by proper watering ; report little gain from spraying musk melons.
58. Stone, G. E. Cucumbers under Glass. Mass. Agr. Exp. Stat. Bull.
87 : 36-7. 1903. [Illustr.]
Gives general account of the downy mildew and preventive
measures.
59. Sturgis. W. C. Downy Mildew on Melons. Conn. Agr. Exp. Stat.
Rept. 1899 : 277-78. 1900.
Gives account of damage done at Meriden, Conn., on musk
melons and advocates starting plants under glass to get an earlier
start and escape in part this trouble.
LITERATURE ON MELON BLIGHT. 36 1
60. Swingle, W. T. Some Peronosporaceae in the Herbarium of the
Division of Vegetable Pathology. Journ. Myc. 7 : 125. 1892.
Lists Peronospora cubensis B. & C, under doubtful section of
this genus, on Cucumis anguria from Texas and Florida, and on
Cucumis sativus from Texas and Maryland.
61. Thaxter, R. Peronospora on Cucumbers. Conn. Agr. Exp. Stat.
Rept. 1890: 97. 1891.
Notes appearance of this fungus, for first time in Connecticut,
at South Manchester.
62. Tubeuf and Smith. Peronospora (Plasmopara) cubensis. Diseases
of Plants: 134. 1897.
Merely list as an injurious species.
63. Waite, M. B. Description of two New Species of Peronospora.
Journ. Myc. 7 : 106. 1892.
Notes the resemblance of his Peronospora Celtidis, n. sp., on
Celtis occidentalis to Peronospora Cubensis B. & C.
64. Weed, C. The Cucumber Mildew. Fungi and Fungicides : 160.
1894-
Gives short account of the fungus.
65. Zimmermann, A. Ueber einige an tropischen Kulturpflanzen beo-
bachtete Pilze II. Centr. Bakt. P^r. Infek. 8: 148. 1902. [Illustr.]
Describes Peronospora cubensis var. atra, n. var., from Buiten-
zorg, Java, or Cuciirbita pepo.
66. Zimmermann, A. Untersuchungen iiber tropische Pflanzenkrank-
heiten. Ber. iiber Land- und Forstwirtschaft in Deutsch- Ostafrika
2:11-36. [Review, Centr. Bak. Par. Infekt. 12:316. 1904-]
Lists Peronospora cubensis var. atra on cucumber leaves from
Dutch East Afrika.
Explanation of Plate XXXI.
Detailed drawings of P eronoplasmo para Cubensis. Magni-
fied about 600 diameters, except i, which is only magnified
about 350 diameters.
1. A single conidiophore emerging from a stomate of a leaf.
2. Base of a conidiophore and lobes of the mycelium from
which other conidiophores develop in favorable weather.
3. Top of a conidiophore, showing an immature (a) and a
mature (b) spore still attached.
4-9. Spores (temporary) that were produced on the conidio-
phores. 4. Contents emptied out through pore of dehiscence.
5. Spore about to germinate, showing areas in the protoplasm.
6. Showing last of about a dozen zoospores escaping from the
spore. 7. A zoospore that failed to escape from the: spore.
362 CONNECTICUT EXPERIMENT STATION REPORT, I904.
8. Cross section of an empty spore. 9. Empty spore, showing
the pore through which the zoospores escaped.
10-12. Motile stage of the zoospores ; 10, showing the sepa-
ration of zoospores into individuals.
13. An unusually large zoospore making an unsuccessful
attempt to divide.
14. Zoospores after coming to rest and before their ger-
mination.
15. Zoospores (in an amoeboid condition) that never germi-
nated and finally died.
16. Different stages of the germination, in water, of the
resting zoospores.
17-20. Infection of the host through germinating zoospores
resting on the epidermis. 17. A zoospore settled down over a
stomate. 18. The same zoospore two hours later, with its germ
tube apparently entering the leaf between the guard cells of the
stomate. 19-20. A resting zoospore (a) on leaf near a stomate ;
(b) its final position after starting to germinate two hours later ;
20, its condition twenty-four hours later, apparently trying to
bore into leaf through the epidermis.
PLATE XXIX.
a. Under surface of leaf showing early stage of blight.
b. Under surface of leaf showing later stage of blight.
BLIGHT, OR DOWNY MILDEW, OF MUSK MELON, Pcronoplasinopara Ctihmsis, p. 344.
^:^-
1^^^
:-.*:^^-
a. Blighted vine in the field, p. 344.
b. Vines in foreground sprayed ; those in rear not sprayed, p. 351.
BLIGHT OR DOWNY MILDEW OF MUSK MELON.
PLATE XXXI.
DETAILED DRAWINGS OF Peronoplasmopaya Ciihcns
BLIGHT OF POTATOES. 365
DOWNY MILDEW, OR BLIGHT, Phyfophthora infestans
(Mont.) DeBy., OF POTATOES.
Aim of Investigations. In 1902 the writer began a series of
spraying experiments with potatoes having two objects in view,
namely, first, to determine just how injurious the bhght fungus,
Phytophthora infestans, is in this state year after year, and
second, to determine the most effective and practical method of
spraying to prevent it. No especial originality is claimed for
these experiments, since the object was to apply chiefly what
the general results of others had determined and see how these
were adapted to the conditions that exist here. -We report in
this paper the results and suggestions that have been gained
so far.
No idea was had at the start of a special study of the fungus
that is responsible for blight, as it has had the attention of many
European botanists. There are a number of points in its life
history, however, that the writer has been forced to believe are
not known, or at least have not been positively settled. A com-
plete knowledge of the fungus must have considerable bearing
in determining the very best ways for controlling the disease.
Consequently, during the past year, efforts have been made to
gain all possible information concerning the fungus itself.
This second phase of the subject is not dealt with especially in
this paper, as it is still under consideration, but as a general
knowledge of the blight fungus is necessary to an intelligent
understanding of the methods employed in combating it, we give
briefly what we understand from our own observations and
those of others to be the main facts in its life history.
Life History of Fungus.
Infected Tubers. To the ordinary observer blight begins in
his field when it shows with the sudden or gradual death of the
vines in the middle of July or later. Its first development,
though hidden, really began when infected tubers in that or
some other field were planted in the spring. In other words,
the blight fungus is carried over the. winter in the tubers from
a previous diseased crop. Furthermore, so far as we nozv
knozv, the fungus is perpetuated only by tlie infected tubers,
364 CONNECTICUT EXPERIMENT STATION REPORT, I904.
and not through diseased tubers that have rotted outdoors, or
by the old rotted vines, or through infection of the land, or on
some other host of the fungus. However, there is a possibility
that one or more of these other means may also serve to per-
petuate the fttngus, but as yet proof is lacking. A good deal
of study has been made on this phase of the subject, but it needs
still more.
The appearance of the disease as ordinarily shown at time
of storage on potatoes is a reddish brown rot that develops only
slowly, if at all, when the tubers become dried out and are kept
in a cool, dry place. This discoloration shows at the surface,
often extending inward from the skin to the bundles or further,
and the surface may also become slightly sunken or pitted.
(See Plate XXXIII, b.-c.) In the fields, and while still
damp in storage, the rotting is often very rapid. This is largely
due to the presence of bacteria or the Fusarium fungus that
develop independently or as a consequence of the blight and are
apparently more active agents of decay. Very often tubers are
found having an end rot, usually the stem end, that affects the
whole tuber as it progresses forward. Not infrequently the
freshly diseased, or innermost, tissues have the same reddish
brown color found in blighted tubers, and probably the fungus
is sometimes present, but usually this end rot seems to be caused
by the Fusarium fungus which breaks out in white fruiting
pustules on the surface. This also becomes a slow dry rot in
storage after the tubers have dried out. The bacterial trouble
is usually shown in the field by a slimy, sticky, ill-smelling rot
that, if first started by the blight fungus, soon outstrips it as
the agent of decay and no doubt often starts independently of
this fungus. In storage it gradually dries out and works slower
and is often found in connection with the Fusarium or other
fungi.
The blight fungus persists in the infected tubers by means of
its mycelium, or its vegetative stage. This consists of micro-
scopic threads that have pushed their way slowly between the
cells of the tuber, occasionally sending short, thick-walled
branches inside the cells to obtain nourishment for growth.
This stage has directly to do with rotting the tubers and blight-
ing the vines, but not with spreading the disease. During the
storage of the tubers it apparently exists in a dormant, or at
least not very active, condition.
BLIGHT OF POTATOES. 365
When infected tubers are planted in the spring the myceHum
may push out on the undiseased cut surface of the tuber from
the diseased tissue and there form the temporary spore, or
reproductive stage, the same that it develops in July or August
on the leaves. This spore development is likely to continue only
for a short time, as the blight fungus is easily crowded out by
other fungi and it does not form this stage at all on rotten
tissues. Some of the spores produced here may be carried acci-
dentally by insects or washed by the rains to the young buds of
the sprouting tuber and on germination infect these with the
disease. Or probably the mycelium as often grows directly
from the diseased tissue into the healthy tissue of the develop-
ing buds and secures infection in this way. It is quite probable
that comparatively few plants in the field become infected
through the diseased tubers ; at least we can say positively from
experiments that diseased tubers do not necessarily produce
infected plants. In an experiment by the writer where badly
rotted blight tubers were planted in a greenhouse, the tubers
either failed entirely to produce plants or else developed plants
in which the disease never appeared, though the fungus grew
out on the cut surface in its spore stage. So far the writer has
not observed in the fields stems developed from infected buds,
but the few seen in the greenhouse remained dwarfed and of a
reddish brown color at the surface, as if the fungus was super-
ficial in the tissues. These infected stems do not produce spores
except under proper conditions of moisture. This fact, together
with their scarcity, possibly explains why the disease is so slow
in getting started in a field, rarely ever appearing before the
middle of July, and often much later. Once the spores begin
to be produced above ground, however, with proper weather
conditions they spread the disease through the field and, no
doubt, to other fields. Just how far and how often the
fungus is carried by these spores from one field to another are
points that need further investigation. Also the whole subject
of the very early development of the disease requires more
observations and experiments.
Blighted Vines. This temporary spore stage may be
described very briefly as follows : The fungus once started in
a leaf, through infection from a germinating spore, develops
its mycelium between leaf cells, killing the tissues as it goes,
366 CONNECTICUT EXPERIMENT STATION REPORT, I9O4.
and also sends out to the exterior through the stomates, or open-
ings in the epidermis, erect branched fertile threads that form
the temporary spores. The spores mature very quickly and
can germinate immediately if they fall in a drop of water.
Many of the spores perish, however, as they cannot live long
in dry air. The germination usually consists in the formation
and liberation of several motile animal-like bodies called
zoospores that swim around in the water for a short time and
then come to rest. They then send out a germ thread that
grows into the leaf tissues and develops the mycelium from
which arise the spore-bearing threads as before. This process
of spore formation, germination, infection and development of
mycelium can be kept up indefinitely, or at least as long as
weather conditions are favorable and there are green potato
leaves left. The wind, rain and insects serve in spreading the
spores. Moist, cloudy weather of several days' duration is
best adapted for the growth and spread of the fungus, since the
fruiting threads are then formed most abundantly ; then con-
ditions are also favorable for the germination of the spores and
infection of the leaves and the diseased area in the leaf develops
rapidly. In dry weather the blackened, diseased tissues of the
leaf dry up, but the fungus makes very little further advance,
while very few new fertile threads are developed on the exterior.
The blackened, diseased spots usually start at the margin of the
leaves and develop inward, and on the under side the spore
threads, especially in moist weather, can be seen as a faint
whitish growth just in advance of the discoloration. (See Plate
XXXII, a.) The character of the weather during July and
August determines largely how much injury the fungus will do
to the vines. If after the disease has spread somewhat through
the fields there comes a period of blight weather, the vines may
all be gone in a week ; or if the weather is less favorable for
its development the disease may lag along slowly. Some
seasons it does not appear until the very end.
Rotten Tubers. It has been stated by some writers that the
blight fungus, through its mycelium, passed down the stems
into the tubers. We have seen no evidence that this is so, and
doubt if it ever (perhaps rarely) occurs. With the Fusarium
and the bacterial rots of the tubers this may be true, since the
disease in these cases often starts in the stem end of the tubers.
BLIGHT OF POTATOES. 367
Infection of the blighted tubers takes place through the spores
that fall on the ground from the infected leaves above. If
these are washed down to the tubers, infection takes place on
their germination by the germ threads boring directly into the
tissues and there developing the mycelium. So far as observed
by the writer, the fungus is not apt to send out fruiting threads
on the surface of these tubers while in the ground and spread
the disease this way. Such fruiting threads, however, have
been seen in potatoes freshly dug and kept in a moist atmos-
phere, and probably are formed somewhat in the ground. The
amount of moisture in the soil while these spores fall on the
ground and the nearness of the tubers to the surface are two
factors in determining the extent of the infection. Severity of
blight in the foliage does not necessarily mean a corresponding
severity of rot in the tubers. At least in July, 1902, there was
a sudden and severe blighting of the vines, many fields being
entirely dead a week after the appearance of the trouble, and
yet there was comparatively little complaint of rot that year.
On the other hand, in 1904 the blight made its appearance very
late in the fields, doing comparatively little injury to the foliage ;
but this year the tubers rotted badly from the blight. The rot
in the tubers does not usually start until the vines are dead.
As mentioned before, all the rots of the tubers are not due to
the blight fungus. In 1903, for instance, the tubers rotted
rather badly, but this was caused chiefly by the bacterial rot
and the Fusarium fungus.
Winter Spores. The spores of the blight fungus are tem-
porary and cannot carry the fungus over the winter, but, as
previously stated, this is accomplished by the mycelium in the
infected tubers. Many of the fungi in the group to which the
blight fungus belongs, however, develop thick-walled oospores
(winter or resting spores), and these serve as a means of per-
petuating such fungi. These spores have been looked for in
connection with the potato fungus, but their existence has never
positively been proven, though some investigators have thought
that they found them. The writer has made a special search
for them, and while some suspicious things have been seen,
no positive evidence of their existence has been gained, though
artificial cultures of the fungus have been grown on various
media in test tubes and search has been made in the potato
368 CONNECTICUT EXPERIMENT STATION REPORT, I9O4.
leaves and tubers in all stages of infection and decay. From
these investigations we are inclined to the belief that if such
spores are formed in this locality they develop only in the rotted
tissues, tubers most likely in the very last stages of their complete
decay ; that is, in the late spring in the tubers left in the fields,
and later in the summer, after rotting to pieces, in the infected
seed tubers. Blighted tubers in this condition not infrequently
contain spores of this nature that look suspicious, but as yet no
positive proof of their connection has been obtained, and as a
number of unrelated saprophytic fungi develop in the rotted
tubers they could easily belong to some of these. It has
occurred to the writer, also, that possibly these oospores are
formed only on the union of two strains of mycelia (which may
rarely occur together), as has recently been shown for a some-
what related group of fungi. In any case, whether this fungus
possesses such spores or not, further study along this phase of
the subject is needed.
Spraying Experiments.
Previous Experiments. Both the former botanists of this
Station made a few spraying experiments that may be briefly
mentioned here. Professor Thaxter, in 1889, when blight was
unusually severe, made one of the very first spraying experi-
ments against this trouble that has been reported. He sprayed
three times with Bordeaux mixture, on July 18, July 25 and
August 3, and got a decided difiference in the foliage between
those sprayed and those unsprayed. On August 3 the sprayed
vines retained 50 to 60 per cent, of their foliage, while the
unsprayed were entirely dead, arid on August 10 the sprayed
vines still retained 25 per cent, of their foliage. Unfortunately
(Thaxter thought possibly due to error in harvesting) the
treatment gave no increase in yield. In 1890 Thaxter reported
a successful treatment by Mr. N. S. Piatt, made after the blight
appeared in the field ; in this case the yield was reported con-
siderably increased. Dr. Sturgis also conducted spraying
experiments in 1892 and in 1893, but both these years there was
little, if any, blight in the sprayed fields, so that his experiments
were chiefly of value in showing what effect spraying has in
vears when blight is not troublesome. He reported consider-
SPRAYING FOR POTATO BLIGHT. 369
able benefit resulting from the treatment the first year, but not
the second, which was a very dry year.
Recent Experiments. The following experiments have been
made personally by the writer in order that he might learn of
the disadvantages as well as the advantages of spraying. They
have been conducted on all scales from a small garden plot to
a five-acre field. The various types of spraying apparatus have
been tried to determine their merits and demerits. The number
of sprayings in each case has been reduced to the minimum,
because it was felt that a maximum number of treatments did
not meet with favor among growers generally. Most of the
treatments, however, were made very thorough, for upon this
thoroughness and the proper time of application largely depends
the success of spraying. Bordeaux mixture (four pounds lime,
four pounds copper sulphate, and forty to fifty gallons water)
was used in all cases, with the addition, when needed, of Paris
green for the potato beetle. The check plants were also usually
sprayed once or twice with Paris' green. In making the
Bordeaux, the lime was slaked in a small amount of water and
then strained into a barrel about half filled with water. The
copper sulphate (kept in stock solution of one pound to one
gallon of water) was poured into another barrel, about half
filled with water. The half-barrel of copper sulphate solution
was then poured into the half-barrel of the lime water, stirring
the mixture as this was done.
No direction was assumed of the sprayed fields as to their
culture, fertilization, etc., and these conditions varied consid-
erably in the different experiments. In testing the yields it was
desired to determine how much more or less the sprayed plats
gave over those unsprayed in number and weight of tubers and
the amount of rot in each. These tests were always made from
the same measured lengths of the sprayed and unsprayed rows,
practically side by side, and from at least two places in the field.
This was to eliminate, as far as possible, any other influence
beside the spraying that might affect the yields.
Spraying Experiments in ipo2.
General Notes. This year the blight appeared suddenly in
July and a number of the fields were ruined by it before the end
of the month. (See Plate XXXII, b.) The weather during
370 CONNECTICUT EXPERIMENT STATION REPORT, I904.
July and August was of the kind especially fitted to develop
blight, being- cold, rainy and foggy, often several days occurring
together with little or no sunshine. By the middle of August
there were few green potato fields in the state. For example,
on August 26, while riding on the train from Unionville to
New Haven, there were counted about sixty potato fields, and
in all of these the vines were entirely dead, excepting three or
four, where the vines were still partially green. Except for the
blight, the fields of late potatoes should have lived until killed
by the frost, which this year, according to the weather bureau
at New Haven, did not occur until October lo and October 22.
Little rot developed in the tubers, the injury being thus largely
confined to this very premature death of the vines.
Exp. I, in Ogden field zvith late potatoes. This field, of
about half an acre, was elevated, stony and the soil naturally
rather poor, but it was well dressed with artificial fertilizers and
the culture was fair. The potato vines did not cover the
ground so densely as they often do in richer, moist soil, so it
was easier to protect this field against blight than one of rank
growth. The first spraying, July 30, was made just after a
small amount of blight appeared in the field. This application
was somewhat tardy, about ten days, but it made less difference
in this field than it would have made in one of luxuriant vege-
tation. The second and third treatments were made on August
5 and August 23, and on the latter date there was evident differ-
ence between the sprayed and unsprayed parts in the injury
from blight. On September 2 the unsprayed plants were nearly
all dead, while the sprayed plants were mostly alive, being the
only green field in the vicinity. At the time of digging, Sep-
tember 25, forty-two of the two hundred and twenty sprayed
plants reported in Table I were still partially green. Plate
XXXVI, a-b, shows the condition of sprayed and unsprayed
plants on September 16. The spraying was done with an ordi-
nary barrel pump carried on a light spring wagon. One man
drove and pumped and one man sprayed about six rows, using
a twenty-five- foot hose with a single nozzle. The wagon reach
was about six inches too narrow for straddling two rows per-
fectly, so the vines were run over somewhat. This caused little
permanent injury, much less than is ordinarily supposed, but
by planting the rows at the right distance or by using a cart
SPRAYING FOR POTATO BLIGHT.
;7i
having the right gauge this trouble can be largely avoided.
The results of the spraying are given in detail in Table I.
This shows that the sprayed plat gave an increase of io8 per
cent, in weight of tubers over the unsprayed plat and the
increased yield was evident not only in the number of market-
able tubers, but also in their larger size. Neither sprayed or
unsprayed potatoes rotted at all. This experiment gave the best
results of any tried during the three years.
Table I — Late Potatoes, Ogden Field, 1902.
Large to me-
Medium to
Total
Very
small
Dug.
dium tubers.
small tubers.
marketable.
tubers.
£
Treatment.
.£3
g
|t.S
J3
e
ili
;yi
P
1^4
&
°z
Z
Z
I^
z
^
z
Z
!^
es
Sprayed July 30,
Sept 25,
August 5,
equal
220*
512
237
871
157
138.3
384
296
i4i
2
August 23.
length
in each
plat.
Unsprayed.
IQ7*
264
io6f
479
78I
743
i85i
248
12
5
* Planted rather unevenly by planter, but possibly part of plants in unsprayed
rows destroyed by blight.
E.rp. 2, in Neshit field after blight started. These potatoes
were on rather rich lowland and the vines were very luxuriant,
entirely covering the ground. When first sprayed, the mildew
was well scattered through the field (not consipcuous, except in
a few scattered patches, where the plants were plainly injured),
and all the conditions were favorable to rapid advance of the
blight with the proper weather. The experiment was under-
taken to determine if in a field of this character spraying would
be of any value when tardily applied. The first treatment was
made August 4 on a small part of the potatoes on either side of
a roadway, spraying in as far as could be reached with the
twenty-five-foot hose. Favorable blight weather followed the
spraying-, and when examined again on August 13 those sprayed
on one side of the roadway were little or no better than those
unsprayed, as both were badly blighted. The potatoes on the
other side of the roadway were apparently of a later planting
and were still green, though severely injured by the blight, and
372 CONNECTICUT EXPERIMENT STATION REPORT, I9O4.
these were given a second treatment. These two sprayings,
however, failed to check the progress of the bhght, and when
finally examined on September 15 the only difference seen
between the sprayed and unsprayed parts was an occasional
partially green plant in the sprayed plat. The rest of the field
was entirely dead. As no influence on the yield was expected
from these results, this was not determined. We conclude from
this experiment that it is useless to begin spraying in a field with
luxuriant foliage after the blight has become well established
and the season is favorable for its development.
Spraying Experiments in ipo^.
General Notes. This season was also wet, though not so
cold or damp as the preceding. The blight appeared consid-
erably later ; the very first found by the writer was on August
8. From this time on it spread through the fields, gradually
killing the leaves until August 24 to 31, when in a period of
weather favorable to blight all of the fields where it had a foot-
hold were quickly ruined. The possible yield was not cut down
so much as the year before by premature death of the vines, but
the rot in the tubers was much more serious. These did not
begin to rot, with the late varieties at least, until the plants were
killed by the blight ; yet from an examination of the tubers the
writer could not find the blight fungus as the agent of the rot.
Most of the tubers examined began to decay at the stem end and
the rot seemed to be caused by bacteria and the Fusarium
fungus. The largest tubers suffered the most. By killing the
green vines the blight fungus probably (indirectly) was respon-
sible for starting these troubles.
Most of the spraying this year was made or started with
geared spraying carts in order to test the efficiency of this kind of
an apparatus. ( See Plate XXXV. ) Spraying by hand requires
more time and men than these machines, where the horse, at the
same time he is pulling the apparatus through the field, is pump-
ing (by means of gearing attached to. the wheels) the Bordeaux
from stationary nozzles that project over the potato rows.
Only one man is needed, and he drives, seated on the cart. Two
machines were used that seemed to be as well fitted for the work
as anv. Our experience with these machines, and our observa-
tion and information concerning others, leads us to conclude
SPRAYING FOR POTATO BLIGHT. 373
that such machines are not to be recommended for applying
Bordeaux mixture against potato bHght. There is need, how-
ever, of some cheap machine that will do the spraying more
rapidly and cheaply, and yet about as thoroughly as can be done
by hand. One of the machines tried had single nozzles for
covering four rows, while the other had double nozzles. Neither
machine could place sufficient spray, well distributed, on the
vines, even by going over the potatoes two and three times, at
the same spraying. Usually the Bordeaux showed as a streak
of blue on the tops of the full-grown vines. The use of sta-
tionary nozzles, even with two to a row and a level and evenly
planted field for spraying, occasionally caused parts of a row to
be missed. The slower the geared machine is driven the less
the power, and yet it is desirable to go slow in order to place
more spray on the vines. Even at their best, these machines
used only about a barrel of the spray to an acre and a half,
whereas two or three barrels per acre is needed to thoroughly
protect the mature vines.
The apparatus shown in Plate XXXIV, b, is a type often
used. In this case the stationary nozzles are attached to the
end of an ordinary cart carrying a barrel pump, and the pump-
ing is done by hand. This, too, has some of the objections of
the geared machines. By very slow driving, however, more
spray can be placed on the vines, but because of the stationary
nozzles it will not be done very thoroughly or evenly. In this
particular apparatus better work would have been done if the
pump had been stronger. It was not powerful enough to
readily supply the eight nozzles used.
By far the most satisfactory type of spraying outfit for
thoroughness of work is that shown in Plate XXXIV, a. This
is merely a two-wheeled cart, of sufficient reach to straddle two
rows of the potatoes, which carries an ordinary barrel pump and
a man to pump and drive. Two men follow the cart, each
using a twenty-five- foot hose with a single nozzle, and they each
spray three rows without moving from the row, in which they
travel backward. The man drives the length of the hose and
the men spray their rows up to the cart, which then moves on
again. In this way the ground can be gone over fairly quickly
and the spraying can be done as thoroughly as desired. Two
nozzles to a hose seem to be little better than one and waste
29
374 CONNECTICUT EXPERIMENT STATION REPORT, I9O4.
more of the material. Where onty two men are available for
the work, only one need be used for spraying. Each hose should
be fitted with a cock at the nozzle and a holder for inserting a
short pole for directing the spray. The chief objections against
this method of spraying are that it requires an extra man or two,
and its slowness ; but, taken altogether, it is the best way known
to the writer for spraying any considerable area thoroughly.
Exp. J, in Farnham field with late potatoes. This level field,
of about six acres, has a rich but slightly sandy soil. The culti-
vation and fertilization were good. The first blight was found
in the field August 8, or after the first two sprayings had been
made. These treatments were made with the geared power
sprayer, but this worked so unsatisfactorily that six rows (plat
A, see Table II) next the four unsprayed rows were sprayed on
August 8 and August 24 by hand, as shown in Plate XXXIV, a.
On August 24 the blight had made such progress in the main
part of the field sprayed by the geared machine that part of this
was sprayed more thoroughly by hand, but this was too late to
materially check the advance of the blight. On this date the
thoroughly sprayed six rows, plat A, were in fair condition,
while the unsprayed rows were two-thirds gone with the blight.
On September 3 the unsprayed rows were entirely dead ; the
imperfectly sprayed main field, plat B, was about as badly gone ;
v^hile the more thoroughly sprayed plat A was still green, having
only about half the foliage destroyed. (See Plate XXXVII.)
The yield, as tested on September 4, gave the more perfectly
sprayed plat A 59 per cent, greater yield by weight than the
unsprayed rows next to it, while the imperfectly sprayed plat B,
which was tested quite removed from the check unsprayed rows,
gave 42 per cent, greater yield. At this date little rot had devel-
oped in the field. As the vines in plat A were still partially green
at this time, a second test of this and the check rows was made
on September 25, after all the vines were dead. This test was
made in rows side by side with the first. It showed that while
plat A had made some increase in weight and number of mar-
ketable tubers during this interval, this was completely offset
by the rot that had developed. The unsprayed rows, however,
being entirely dead, had made no increase and had suffered
more severely through rot. So on the second digging the
sprayed plat A showed 91 per cent, increase in weight over the
SPRAYING FOR POTATO BLIGHT.
375
unsprayed. This experiment indicates that the rot starts soon
after the death of the vines, usually in a week or so, as was
shown in the digging of the main field.
Table II. — Late Potatoes, Farnham Field, 1903.
Large to
Medium to
small tubers.
Total
marketable.
Very small
tubers.
Rotten
tubers.
Dug
(200 fe
-t).
c
"H,
Treatment.
g
3
Mm
B
z
u
B
3
s
z
M„-
6
Z
'5-0
(A) Sprayed ;
July 10, Aug. I,
Aug. 8, Aug. 24.
Sept.
Sept.
4
25
129
119
151
53
72
27i
563
651
i5oi
714
704
187
178
125
172
7
8f
0
50
14
Unsprayed, or
Sept.
4
126
29
13
618
I04i
647
ii7i
123
6i
5
Check.
Sept.
25
127
II
6
369
82
380
93
143
9
104
25
(B) Imperfect-
ly sprayed : July
10, Aug. r, Aug.
Sept.
4
130
140
67
444
100
574
167
62
4
4
24.
E;!:/). ^, in Farnham field with late variety planted very late.
This was in the same field reported in experiment 3, but the
potatoes were not planted until about the middle of June.
The experiment was to determine if such late planting on land
used earlier in the season for other crops was feasible if the
potatoes were sprayed to ward oif the blight, which might other-
wise carry them off before the tubers were of marketable size.
Unfortunately only two treatments were made. Doubtless three
would have given better results, especially if the first had been
made a little earlier. At the time of the first spraying, August
8, a little blight was found on these plants, but it was not nearly
so abundant as in the unsprayed part of the earlier planted
potatoes. On August 24, at the time of the second spraying,
the fungus was common in the check rows of the unsprayed
late-planted potatoes, but still was not nearly so abundant as in
the unsprayed early planted potatoes. This confirms DeBary's
statement that blight generally seems to develop most promi-
nently in a field when the vines are in their prime of development.
On September 3 the unsprayed rows were very nearly gone with
376 CONNECTICUT EXPERIMENT STATION REPORT, I9O4.
the blight, while the sprayed rows still retained half of their
foliage. The sprayed plat was dug September 25, when the yield
was found to be a little greater and the rot a little less than in the
unsprayed plat of the early planted portions of the field. It was
not possible to compare it with its proper check, since this had
been dug by accident a few days before, but the man in charge
said that these unsprayed rows had yielded very poorly. It
would seem from this experiment, then, that where it is very
desirable to use a field for another crop until the middle of June,
a moderate yield of potatoes can be secured from it afterward if
these are thoroughly sprayed three times to ward off the blight.
Exp. 5, in Ogden field with early and late potatoes. This
field contained about one acre and a half of rather level and
medium rich land. The day before planting the potatoes the
green rye on the field was plowed under. Dry weather fol-
lowed, so that the potatoes were a long time coming up, and
a very uneven stand was made, as many of the plants never
came up or were rotted ofif below the ground by a bacterial rot.
Without much question, the humus of the decaying rye had
much to do with this stem rot and the severe rot of the tubers
that developed later. The field was very poorly cultivated and
became very weedy. All of these conditions were against the
potatoes. The vines were sprayed three times (July 5, August
II, September i), twice with the geared spraying machines
and once with the stationary nozzle outfit shown on Plate
XXXIV, b. It was impossible with either of these appliances
to properly cover the foliage, even by going over the field two
and three times each spraying. Consequently the spraying was
done very imperfectly. August 11, at the time of the second
spraying, blight was first noticed in the field, being most
abundant on the unsprayed early potatoes. September i the
blight was quite prevalent in the field and with but slight dififer-
ence in favor of the sprayed parts. When dug on September
21 all of the vines had been dead for some time. The rot,
which developed very badly, was largely a soft bacterial rot. A
field nearby suffered very little from rot. The sprayed plat of
the late variety, which constituted most of the field, gave 20 per
cent, less yield by weight than did its unsprayed plat. This
was the only experiment during the three years in which a
smaller yield was got from a sprayed than from an unsprayed
SPRAYING FOR POTATO BLIGHT.
377
plat, but even here the yield was originally greater in the sprayed
plat, but lost through more severe rotting of the tubers. The
early variety, however, gave an increase of loo per cent, for the
sprayed over the unsprayed vines. Because of the imperfect
spraying and the development of severe rot, probably due to
plowing under the green rye, the experiment was not very
satisfactory. See Table IIL for details.
Table III. — Late and Early Potatoes, Ogden Field, 1903.
Dug.
(loofert.)
a,
S
Z,
Large to
medium
tubers.
Medium to
small
tubers.
Total
marketable.
Very small
tubers.
Rotten
tubers.
Treatment.
C
E
Z
s
1
1"
E
1
u
s
3
A. Late variety.
-
Imperfectly
sprayed :
July 15, Aug. II,
Sept. I.
Sept. 21
64
6
3
92
17
98
20
96
4
165
22
Unsprayed :
Sept. 21
64
2
I
131
23
133
24
188
9
81
II>^
B. Ea7'ly variety.
Imperfectly
sprayed :
July 15, Aug. II,
Sept. I.
Sept. 21
60
2
^%
223
35
225
36>^
126
6
74
10
Unsprayed :
Sept. 21
55
0
0
92
18
92
18
73
4
39
6
Spraying Experiments in 1^04.
General Notes. This year was drier and warmer than either
of the two preceding years and did not develop special blight
weather during July or August. The very first blight seen was
on August 3, but September found most of the late potato fields
still green, and it was during the moist weather of this month
that most of the injury to the foliage was done. Coming so
late in the season, however, this injury would have been insig-
nificant, and a large crop would have been harvested, but for
the fact that this late blighting served to supply the spores that
during the moist weather of September and October started a
very serious and widespread rot of the tubers. Unlike the pre-
3/8 CONNECTICUT EXPERIMENT STATION REPORT, I904.
ceding year, this rot could be directly traced in its beginning
to the blight fungus. The rot started at any place on the tubers,
attacking small as well as large ones when severe, and showed
the characteristic sunken areas with reddish brown discolora-
tion of the superficial tissues beneath. There is little doubt,
however, that after the blight fungus started the trouble, bac-
teria were often responsible for extending it, even outstripping
the blight fungus in their progress and injury.
Exp. 6, in Farnham field with early potatoes and early spray-
ing. This was a level, rather low field of rich but slightly
sandy soil, and was well fertilized and thoroughly cultivated
during the season. The aim of the experiment was to deter-
mine if spraying would prove profitable in a field of early
potatoes that were to be dug and sold, at least in part, as soon
as they were of marketable size. As the earliest potatoes are
often dug for the market about the time that the blight appears,
it was not expected that benefit would result so much from
preventing blight as it would from better protection against
potato bugs and flea beetles, and from the stimulation that
Bordeaux mixture seems to give potatoes even when free from
fungus attack. Blight was so late in appearing that it was not
found in this field even on the unsprayed vines. The gain
from spraying, therefore, resulted entirely from better protec-
tion of the foliage from insect attack and from the stimulative
action of the Bordeaux mixture. The spraying was made with
the barrel pump mounted in a cart and was done very thor-
oughly. The first treatment was given June 17, and the second,
on July 7, was made on only part of the field next the unsprayed
rows. The difiference in appearance of foliage between the
sprayed and unsprayed plats on July 7 was marked. In the
plats sprayed with Bordeaux mixture one pound of Paris green
per barrel was used, and as the foliage was thoroughly covered
and the sediment adhered through the season, this protected
the vines completely from the potato beetles. The check rows
also had been sprayed twice with Paris green only (by the
owner), with a geared spraying machine. The spraying by
this method was imperfectly done and there was nothing to keep
the poison from washing off by rains, so these vines suffered
severely from attack by the bugs, and as no lime was used with
the Paris green this also burned the foliage considerably. The
SPRAYING FOR POTATO BLIGHT.
379
•first digging was made on July 20, as soon as the tubers were
ready for market. Despite the injury from the bugs and Paris
green burn, the unsprayed plat at this digging yielded about as
well as either the plat sprayed once, which gave only 3 per cent,
greater yield by weight, or the plat sprayed twice, which gave
5 per cent, greater yield. As the sprayed plants at this time
were still in their prime and the unsprayed plants nearly dead,
a second test was made August 5, after all the plants were about
gone. The test showed an increase of 8 per cent, in those
sprayed once and of 17 per cent, of those sprayed twice over
the unsprayed plat. There was no loss from rot. This experi-
ment indicates that, where early potatoes are dug as soon as
marketable, spraying with Bordeaux mixture does not pay, but
when these potatoes are left until the vines are entirely dead
the spraying will be of greater value, especially if early blight
has been injurious or the late blight appears before the end of
their season. There is no doubt that Paris green used in Bor-
deaux is more effective in repelling attack of the potato beetle
and even the flea beetle than when used alone, and there is then
absolutely no danger of burning the foliage. It is the extra
cost of applying the Bordeaux mixture, especially if labor is
an important factor, that largely offsets its benefits in spraying
early potatoes, unless these are severely injured by preventable
fungus attack. For details of experiment, see Table IV.
Table IV. Early Potatoes^ in Farnham Field^ 1904.
Dug.
(200 ft.)
c
"3.
E
a
2;
Large
dium
to me-
ubers.
Medium to
small tubers.
Total
marketable.
Very small
tubers.
u
Treatment.
u
S
3
2
>
S
3
2
.a
B
Z
43
S
z
J5
3
C
0
Pi
Sprayed once, June 17.
July 20
Aug. 5
146
4
22
3
13
1007
1022
I97K
206
lOII
1044
200^
219
319
356
I2>^
15
0
2
Sprayed twice, June
17, July 7.
July 20
Aug. 5
148
4
34
2^
20
III4
1034
210
224>^
III8
1068
212'/^.
244 ^^
294
400
13
16
0
2
Unsprayed.
July 20
Aug. 5
148
17
20
12
998
184
1 96
932
IOI8
195'/^
208
387
334
15
15
0
0
380 CONNECTICUT EXPERIMENT STATION REPORT, I904.
Exp. Y, in Farnham field with late potatoes. This was an
acre field of about the same character as the preceding, except
the cultivation given the potatoes was very poor. As a result
the field became very weedy, which somewhat hindered spray-
ing, and the tubers were formed so close to the ground that they
were easily reached by the spores of the blight fu7tgus and so
suffered severely from rot. All the potatoes except three check
rows were sprayed four times, using the barrel pump mounted
on a cart, namely, on July 7, July 20, August 5 and August 20.
As the potatoes were planted very late, the first spraying was
made when they were only eight to ten inches high. The vines
were severely attacked by potato bugs, especially the check rows,
though these were sprayed twice by a geared machine with Paris
green only. On August 5, or at the time of the third spraying,
no blight was found in the field. The writer was not present
at the fourth spraying, but when examined again on September
8 the unsprayed vines were all dead, though the stems were still
green, having apparently been injured chiefly by the potato
bugs. The sprayed vines were still green, but now showed
many blighted leaves scattered through the field. The fungi-
cide at this time was almost all off the foliage and the wet Sep-
tember weather that followed rapidly developed the blight, so
that at the end of the next ten days the vines were mostly dead.
The effect of this delayed appearance of the blight was to
develop a serious rot of the tubers, especially in the sprayed plat,
for the vines in the unsprayed plat had largely died before the
appearance of the blight. If the potatoes had been properly
cultivated, and especially if the tubers had been buried deeper
under the soil by some system of ridge culture, it does not seem
likely that the rot would have developed nearly so badly. The
potatoes were not dug for the test until October 4, when it was
found the rot had become very serious, especially in the center
of the field, which was slightly lower and probably more moist.
The rot apparently had developed recently, as the lower end of
the field when dug a week or ten days before revealed little
rot. The test showed that while the sprayed plat developed
much more rot (half the tubers were rotted) than the unsprayed
plat, it still gave a yield of sound tubers 73 per cent, greater in
weight. For details, see Table V.
SPRAYING FOR POTATO BLIGHT. 38 1
Table V. Late Potatoes planted late, in Farnham Field, 1904.
Dug.
(200 it.)
Number
plants.
Large to
medium
tubers.
Medium to
small
tubers.
Total
marketable.
Very
small
tubers.
Rotten
tubers.
Treatment.
u
E
1
1
£
1
.£3
e
1
e
s
.5?
1
J3
a
XI
Sprayed, July
7, July 20,
Aug. 5, Aug.
20.
Oct. 4
Not
Recorded
5
4
367
68>^
372
72i
190
7i
370
82
Unsprayed.
Oct. 4
3
2
265
40
268
42
441
14
44
4
^^.r/j. 5, w Clinton garden with early and late potatoes. This
garden is in an isolated spot, well shut off by trees and hills
from any other garden or field, and has been in use only two
years. Whether this accounts for it or not, it is a fact that dur-
ing these two years blight has been slower in appearing here and
less injurious than in almost any place observed by the writer.
The location is rather low, and moist at one end, and the soil
is derived largely from red rock, but with plenty of humus.
These potatoes were sprayed with one of the compressed air
knapsack sprayers, which work fairly well when comparatively
small patches are to be sprayed. The blight did little damage
to the early potatoes and developed in the late abundantly only
Table VI. Late and Early Potatoes, in Clinton Garden, 1904.
Dug.
(50 ft.)
c
"3.
\^
s
Large to
medium
tubers.
Medium to
small
tubers.
Total
marketable.
Very small
tubers.
Rotten
tubers.
Treatment.
J3
S
■ 3
6
3
Z
J3
B
3
a
3
z
Mm
"Exi
a
3
z
'53x1
A. Early Potatoes.
Sprayed June 23,
July 2
Unsprayed
Oct. 6
Oct. 6
33
33
4
0
2i
0
184
38i
29
192
150
41
29
30
53
2i
3
17-
f
3f
B. Late Potatoes.
Sprayed July 2,
Jiily 27
Unsprayed
Oct. 6
Oct. 6
32
36
11
II
8
8
161
163
47
42
172
174
55
50
27
27
li
7
6
2^
f
382 CONNECTICUT EXPERIMENT STATION REPORT, I9O4.
at the very end of the season. These latter should have had one
or two more sprayings. There was very little rot, probably
because the tubers were well covered by earth through ridge
culture; the patch was a decided contrast, in this respect, with
the Farnham field, Exp. 7, which was dug- a few days before.
The early potatoes gave an increase of 41 per cent., but the late
only 10 per cent, over their unsprayed rows.
Summary and Conclusions.
The blight fungus, Phytophthora infestans, while by far the
worst fungous pest of the potato in Connecticut, is often held
responsible for any serious injury to the vines or rot of the
tubers. The Rhizoctonia fungus, the early leaf blight, the
Fusarium fungus, the bacterial stem rot, the wet bacterial rot
of tubers and the well known scab are all parasitic agents at
work in our potato fields and cause more or less injury. Con-
siderable burning of the leaves is also done by the careless use
of Paris green. In dry seasons, due to uncontrolled loss of
moisture, tip burn of the leaves may develop.
During the three seasons 1902, 1903, 1904, which were years
more moist than the average, the potatoes in this state suffered
rather severely from blight, the crops being cut down at least
25 per cent. In 1902 the sudden and early blighting of the
vines prevented a large yield, but there was little rot; in 1903
the yield was affected somewhat by the blighting of the vines,
but was decreased chiefly by bacterial and Fusarium rots of
the tubers that were apparently started by the premature death
of the vines ; while in 1904 blight was so late in developing
that it did little injury to the vines, but did develop a serious
rot of the tubers that carried off a large percentage of the
crop.
Early potatoes suffer very much less from blight, especially
in limiting the life of the vines, than the late varieties. This,
is because the blight often appears only toward the end of their
season and sometimes not until they are entirely gone. It
might be advocated, then, that early potatoes should largely
supplant the late varieties. The yield from the late varieties,
however, aside from serious injury from blight, is considerably
greater, and because of this, and probably for other reasons, the
late varieties generally seem to be much more in favor with
SPRAYING FOR POTATO BLIGHT. 383
growers. Early potatoes, too, are not exempt from serious
troubles.
There is no doubt that the character of the season is the
dominant factor in determining how little or how much damage
will be caused by blight. Rainy weather in July and August
starts the fungus in the fields, and if there then comes a con-
tinuous period of rainy, cloudy or foggy weather the foliage
will soon be destroyed. Wet weather in August or September
following the blighting of the vines determines largely the
amount of rot that develops in the tubers.
Besides the weather conditions, the moisture capacity of each
field or portion of a field no doubt determines largely in a wet
season the amount of rot that develops. This moisture in the
soil is determined largely by elevation, drainage, mechanical
character of the soil and its humus content. Other conditions
heing equal, well-drained, light, sandy soils apparently develop
the least rot. As manure adds to the humus of the soil and is
a carrier of certain troubles, as scab, etc., artificial fertilizers,
rather than manure, should be used on the land the year it is
planted with potatoes.
As the blight fungus, so far as known, carries over the winter
only in the seed potatoes, the first step in lessening the disease
should be with the selection of seed as free as possible from
this and any other fungus disease, as scab, Rhizoctonia, etc.
The selection of even perfect seed will not secure freedom from
blight, as this trouble is often carried from one field to another
after its general appearance ; but it possibly may defer the time
of its attack and lessen the injury.
Thorough cultivation tends to conserve the moisture of the
soil in a dry season (when there is little danger of rot) and in a
wet season it helps to keep the ground from becoming wet and
soggy. Ridging the rows as late as possible in July holds up
the vines from the ground and thus aids in a quicker evapora-
tion of moisture from the foliage and ground, and in so doing
aids in retarding the spread of the blight. It also covers the
tubers deeper in the soil and so protects them better from the
l)light spores that fall from the leaves. Where spraying is
practiced it also makes this operation easier. The objection to
ridging is that in a dry season it may cause the plants to suffer
for lack of moisture.
384 CONNECTICUT EXPERIMENT STATION REPORT, I904.
The results of spraying with Bordeaux mixture vary vyith
different seasons, but depend largely on the thoroughness of
the treatments and their application at the proper time. It is
much easier to secure an increased yield of potatoes from spray-
ing than it is to prevent rot in these afterward. This increased
yield varies from almost nothing to sometimes over loo per
cent., and the rot of the tubers is usually less in the sprayed than
in the unsprayed fields. An average gain of 15 to 20 per cent,
should be had in order to pay for the extra cost and trouble of
spraying ; any gain above that is profit.
When late potatoes are to be sprayed for blight, the writer
advocates three or four thorough applications, the first to be
made July 5 to 15, according to the weather, and the final one
the last of August or first of September. Paris green, if
needed, can be used in the Bordeaux, half a pound to the barrel.
Two to three barrels of the mixture should be used per acre at
each spraying. Aim to have the vines thoroughly protected
with the fungicide when the Ijlight weather appears.
Geared spraying machines are rather unsatisfactory for spray-
ing Bordeaux mixture, since they cover the vines very imper-
fectly with the spray. If used, the vines should be gone over
two or three times each spraying. The barrel pump mounted
on a cart that can straddle two rows of potatoes, and one man
to drive and pump and one or two men to follow on foot, each
with a twenty-five-foot hose, treating three or four rows, is
the most thorough way of spraying a field. (See Plate
XXXIV, a.)
When there is danger from rot the potatoes should be dug
only in bright weather, after the dew is off the vines, and they
should be spread out to dry off and be gathered up before
evening. When the vines are blighting it is difficult to dig the
potatoes without the spores coming in contact with the tubers,
so some advocate leaving the potatoes in the ground at least
ten days or two weeks after the death of the vines. Potatoes
should be dried as thoroughly as possible before storage and
should finally be stored in a dry, cool place. A little dry air-
slaked lime dusted over them no doubt aids somewhat in their
drying out.
PLATE XXXII.
a. Green leaves showing early stage of blight, p. 366.
b. Blighted field which less than week before photographed was perfectly green, p. 369.
BLIGHT OF POTATO, Phytophthora infcstans.
PLATE XXXIII.
b. Section through blighted tuber, p. 364.
a. Late stage of bliglited leaves, p. 366.
c. Blighted tuber, pitted and discolored reddish brown.
BLIGHT OF POTATO, Phylophthora infcstans.
PLATE XXXIV.
a. Best method for spraying potatoes, because the work can be done thoroughl}^ p. 373.
b. Less satisfactory, laecause of stationary nozzles ; pump, also, was not powerful
enough to use the eight nozzles, p. 373.
SPRAYING FOR POTATO BLIGHT.
PLATE XXXV
(X
PLATE XXXVI.
a. Spra3'ed plant in Ogden's field ; photographed Sept. i6, igo2, p. 370.
b. Check or unsprayed plant in Ogden's field ; photographed same dale, p. 370.
SPRAYING FOR POTATO BLIGHT, Pliylophlliora iii/rslaits.
PLATE XXXVII.
CJ
CT-
T3
M
o
'o
Ul
0 (o
State of Connecticut
REPORT
OF
The Connecticut Agricultural
Experiment Station
FOR THE YEAR 1905
PART V
REPORT OF THE STATION BOTilNIST
CONNECTICUT
AaRICULTURAL EXPERIMENT
STATION
REPORT OF THE BOTANIST
G, P. CLINTON, Sc. D,
I. Notes on Fungous Diseases, etc., for 1905.
II. Downy Mildew, Phytophthora Phaseoli Thaxt., of Lima Beans.
III. Downy Mildew, or Blight, Phytophthora infestans (Mont.) DeBy., of
Potatoes. II.
ISSUED MAY, 1906
NOTES ON FUNGOUS DISEASES FOR I905. 263
REPORT OF THE BOTANIST.
NOTES ON FUNGOUS DISEASES, ETC., FOR 1905.
Fungous diseases during the year 1905, on the whole, were
less troublesome to cultivated plants in Connecticut than for
several years past. This was due to the comparatively dry
growing season up to the first part of August. From this time
on, however, the weather was sufficiently moist to develop a
few troublesome diseases, belonging chiefly to the downy
mildew group. The more important of these were as follows :
Brown rot of peach, Sclerotinia fructigena, probably took off
a third of the crop and was much worse than usual, being one
of the most serious fungous outbreaks of the year. The
injury was induced by the rainy weather coming on just about
harvest time. The loss from rot was felt most seriously in the
Wallingford district. Plums, also, were injured but less
noticeably.
The downy mildew of grapes, Plasmopara viticola, was
more abundant than usual this year but no especial complaints
were received concerning it.
Muskmelons, though not now so generally planted because
of injury from fungous enemies, were largely a failure,
partly because of the attacks of the leaf mold, Alternaria Bras-
sicae var. nigrescens, and of the downy mildew, Peronoplas-
mopara Cubensis. The latter fungus was also injurious to the
cucumber, though the injury was not so great as in 1901 and
1902.
The downy mildew of lima beans, Phytophthora Phaseoli,
was more destructive than it has been since 1897. The oos-
pores of the fungus were found for the first time, though the
writer and others had previously looked for them very care-
fully. The fungus is discussed in detail in a special article
later in this report. The rust of string beans, Uromyces
appendiculatus, also seemed to be more prevalent than usual.
The downy mildew, or blight, of potatoes did not appear
until after the middle of August. By that time the combined
injuries of potato bugs, flea beetles, dry weather, and early
264 CONNECTICUT EXPERIMENT STATION REPORT, I9O5.
blight (this last being more prominent than usual) had killed
the potatoes in many fields, so that these, missing the blight on the
foliage, did not suffer subsequently from rot of the tubers.
Those fields, however, that were still green when the blight did
appear were gradually killed by it and the tubers often rotted
considerably. Thus, while there was considerable com-
plaint of rotten potatoes, this injury was not as great as in
1904, and the blight injury to the foliage was still less
conspicuous.
Point-rot of tomato did some damage to the fruit — more
than has been noticed for several seasons. It was not deter-
mined whether this trouble was due to bacteria or fungi,
but superficial observations seemed to indicate both as pri-
mary agents of the disease.
New Diseases.
The following troubles were not necessarily especially
injurious in 1905 but are briefly described here because they
have not been mentioned before (see Reports of Botanist for
years 1903 and 1904) as occurring in Connecticut.
APPLE, Pirus Malus.
Fruit Speck_, Fungus undet. Plate XIII, a. In February,
1905, Mr. E. M. Ives of Meriden gave to the writer for exami-
nation specimens of apples showing superficial small spots or
specks scattered over the skin. This trouble, while observed
by Mr. Ives at harvest time, did not develop conspicuously
until some time after storage. The same trouble has been
observed by the writer the present winter on apples in the
New Haven markets and also on specimens of the Tallman
variety at the mid-winter exhibition of the Connecticut Pomo-
logical Society. These areas of brownish dead tissue usually
varied from the size of a pin head to a quarter of an inch in
diameter and extended but slightly into the flesh. The dis-
eased spots in some cases were even more thickly placed than
on the Tallman Sweet in the illustration given here. Frequently
one could see at the center of the specks small ruptures, as if
made by insect-puncture, or possibly the trouble started at the
lenticels and these were of that nature. Cultures in test tubes
were made at different times by taking diseased tissue beneath
NOTES ON FUNGOUS DISEASES FOR I905. 265
the epidermis with a sterilized knife and these all developed a
fungous growth but in some cases mixed with bacteria. As
the fungus was apparently the same in all the cultures, pre-
sumably it was the primary cause of the trouble, but it cannot
be a very aggressive parasite since the spots remained so small
and developed so slowly even on the stored fruit. Neverthe-
less it is a serious pest for certain varieties in that it greatly
mars their appearance and possibly later opens the way for
more extended and deep-seated rotting. According to Mr.
Ives, Tallman Sweet was the variety most seriously affected,
Northern Spy suffered less, while Baldwin was injured but
little. From this it would appear that the more tender or
earlier maturing winter varieties were more susceptible of
attack. Mr. Ives also informs the writer that these apple trees
were sprayed in 1905 and the disease did not trouble the crop
of that year. No reference in literature has been seen that
relates to this trouble, which apparently is a common one.
BEAN, LIMA, Phaseohts hmatus.
Pod and Leaf Blight,, Phoma subcircinata E & E. Plate
XIII, b. Halsted in 1892 briefly mentioned in the 12th Ann.
Rep. of N. J. Agr. Exp. Stat., p. 287, under the name of Phyl-
losticta sp., a fungus collected on the pods and leaves of Lima
beans. In 1893 Ellis also described, in the Proc. Phil. Acad.
Nat. Sci., a new fungus on the pods of Lima beans, calling it
Phoma subcircinata E. & E. In a more detailed description
in Bull. 151 of the N. J. Agr. Exp. Stat., p. 24-5, Halsted
identifies Ellis' fungus as the one to which he had previously
referred. The past year the writer found a fungus, apparently
the same as described and illustrated by Halsted, on the
leaves of Lima beans in the vicinity of New Haven. It was
not observed on the pods but may have escaped notice because
it was not especially looked for there. While attacking leaves
here and there on the plants, the injury was not especially con-
spicuous in the field. The fungus produced large subcircular,
or more irregular, brown, often bordered, spots that gave
evidence of their development through faint, elevated, con-
centric rings of growth. The spore receptacles showed as
numerous small black specks immersed in the tissues. In time
the dead tissues cracked more or less and wore away, leaving
17*
266 CONNECTICUT EXPERIMENT STATION REPORT, I905.
holes in the leaves. Our specimens do not agree exactly with
those issued by Ellis (N. A. F. No. 2840) on the pods, since
their spores average larger, 5-12/^ by 2.5-3.5/x, and are occa-
sionally septate. This might be considered by some sufficient
to place the fungus under the genus Ascochyta, and Saccardo
has described a species, A. Phase olorum, with spores 10 by
3ju,, that possibly may be the same as this.
BUTTERNUT, Juglans cinerea.
White Mold, Microstroma Juglandis (Berang.) Sacc.
This is not an uncommon parasite of butternut leaves, forming
white moldy growths more or less thickly on their under sides.
Presumably it is not a serious pest. Dr. Britton collected speci-
mens on wild butternuts the past summer at New Canaan.
CATALPA, JAPANESE, Catalpa Kempferi.
Leaf Spot, Macrosporium Catalpae E. & M. Plate XIV, a.
This trouble was conspicuous during the past summer on a
Japanese catalpa at the Experiment Station. Reddish brown,
bordered spots, 5 to 10 mm, in diameter, are formed more or
less abundantly on the leaves. The tissues of these spots are
dead and often crack apart, sometimes falling out. When the
trouble is serious the trees are partially defoliated. It has been
observed on different species of catalpa in various parts of the
United States and has been discussed most extendedly in the
Ann. Rep. U. S. Dept. Agr. for 1887, pp. 364-5. Experiments
are reported there in which spores of this fungus, and also of
another -found with it, failed to produce these spots when sown
on catalpa leaves. From what the writer saw of the disease
he has been led to believe that possibly the Macrosporium
(Alternaria) develops on the leaves as a consequence and not
as the cause of these dead spots. The fungus belongs to a
genus whose species are more often saprophytic than para-
sitic and are apt to occur on dead tissues. . The spores were
found only sparingly on the dead spots and sometimes did not
seem to be present. No other fungus, however, was observed
on these, and so if they were not caused by the Macrosporium
they probably were not the result of injury by any other fun-
gus. Further study of the trouble is needed to definitely
determine its cause.
NOTES ON FUNGOUS DISEASES FOR I905. 267
GELEEIAC, Apium graveolens var. rapaceum.
Leaf Spot^ Septoria Petroselini var. Apii Br. & Cav.
Plate XIV, b. Celeriac is merely a variety of celery having a
swollen base. It is not largely grown in Connecticut, but
specimens raised for the New Haven market were found to be
injured by the leaf trouble which so frequently occurs here on
celery (see Report of this Station for 1903, p. 314).
DANDELION", Taraxacum officinale.
RusT^ Puccinia Taraxaci Plow. This rust, so common on
dandelions as weeds, was also observed on dandelions cultivated
by a Highwood market gardener ; but it was not causing serious
injury. The spores form dusty reddish brown outbreaks, about
the size of a small pin-head, scattered more or less thickly over
either surface of the leaves.
MAPLE, SUGAR, Acer saccharum.
Leaf Scorch. Plate XV, a. During the past summ.er and
fall maple leaves similar in appearance to that shown in the
illustration were sent to the Experiment Station from different
parts of the state with inquiry as to the cause of the trouble.
Similar specimens and requests have been received in years
past. The leaves die at the margins, forming irregular brown
patches extending inward a greater or less distance. Sometimes
isolated spots are formed wholly surrounded by healthy tissue.
In time there often appears a more or less conspicuous black-
ish growth of saprophytic fungi on the dead tissues. The
appearance of affected leaves moreover is very similar to that
produced by a true fungous parasite of the maple, namely
Glceosporium saccharinum. In no case, however, was this fun-
gus found on the leaves sent in for examination. The trouble
is undoubtedly a physiological one, such .as has been described
by Stone of Massachusetts and Stewart of New York as occur-
ring in those states. For some reason (due probably to drought
or winter injury to the roots) the leaves under certain weather
conditions are not able to replace the water in their tissues from
the roots as rapidly as it is lost through transpiration, and the
death of the tissues from the margin inward results. Accord-
ing to Stone the trouble may be produced by unusually favorable
268 CONNECTICUT EXPERIMENT STATION REPORT, I905.
conditions for the transpiration of water, such as high winds on
clear warm days, when the available water supply of the roots
is small. Most observers report the trouble as appearing sud-
denly, A somewhat similar injury to elm leaves, apparently due
to the same causes, has also been reported frequently in the
state.
NECTARINE, Prunus Persica var, necturina.
Brown Rot^ Sclerotinia fructigena (Pers.) Schrot. The
nectarine is only occasionally grown in the state, but these few
trees seem to suffer considerably from fungous attacks as well
as from winter injury. Specimens of the mummied fruit col-
lected in January showed abundance of the Monilia stage of the
brown rot fungous. While this is very common on other species
of Prunus in the state, it has not been reported before for this
host though apparently not uncommon on it.
Scab, Cladosporium carpophilum Thm. Plate XV, b. In
September specimens of nectarines were received from Thomp-
son, Conn., that were badly injured by the scab fungus which
is so common in Connecticut on the peach. As the nectarine is
a smooth fruit, the injury more nearly resembles that produced
by scab on plums than that on the peach. The skin becomes
more or less thickly covered with the circular, brownish scab
colonies which occasionally merge together. The fungus incites
the formation of a corky growth of tissues and causes more or
less cracking in these. The badly infected fruit is said to drop
prematurely or else mature imperfectly. As in the plum, the
injury to the tissues is more conspicuous than the fungus, while
on the peach it is the olive fungous growth that forms the con-
spicuous spots, the hairy covering no doubt protecting the fruit
somewhat and at the same time permitting a more vigorous
external growth of the parasite. An examination of the twigs
seemed to indicate that the fungus carried over the winter on
these as it does on the peach. The preventive measures are the
same as those for peach scab (see Report 1903, p. 340)-
OKRA, Hibiscus esculentus.
Wilt, Neocosmospora vasinfecta (Atk.) Sm. Plate XVI,
a-b. This fungus is very injurious to cotton in the south and
was first described by Atkinson (Bull. Ala. Agr. Exp. Stat., 41 :
NOTES ON FUNGOUS DISEASES FOR IQOS- 269
19-24) in 1892. He mentions in this bulletin, p. 25, that okra,
which is botanically related to cotton, is sometimes attacked.
Smith (Bull. U. S. Dep. Agr., Div. Path., 17: 31) and
Orton {Ibid, Bull. 2y : 6) both mention okra as having a wilt
disease which they consider the same as that of cotton though
their identity has not been absolutely proved. Okra is a salad
plant occasionally grown in private gardens in this state. Some
plants in the Experiment Station grounds the past year showed
unmistakable signs of the disease in August and September.
The year before some cotton had been grown in the garden a
short distance from where the okra was situated. If the
disease occurred on this, however, it escaped notice. There are
a number of these wilt troubles of cultivated plants that have
been described as distinct, such as wilts of cotton, cucurbits,
potato, tomato, flax, etc. Several of these occur in this state
and the tomato trouble has been especially bad in the Experiment
Station greenhouse for years. As they are all caused by Fusa-
rium soil fungi (of which the mature stage has been observed
only in one or two cases) and these act much the same on all
of the hosts, there may be some question whether they are
really caused by different species or merely strains of the same
semi-parasitic soil fungus.
The diseased okra plants when first seen by the writer in
September looked as if they had been partially killed by the
frost ; see Plate XVI, a. The trouble showed first on the lower
leaves, gradually affecting those above in succession. They
became yellowish in irregular streaks from the margin inward
and eventually brown and dead. In time the whole leaf is killed
and it is usually dehisced at the customary place on the node ;
see Plate XVI, a. Thus a badly diseased plant may gradually
drop all of its mature leaves and finally begin to die at the tip
of the stem. The character of the disease is shown on cutting
transverse or longitudinal sections of the stem. The woody
layer. which occupies a prominent band between the central pith
and the outside bark appears in these cases plainly diseased,
having a dark brown color ; see Plate XVI, b. This discolora-
tion of the wood even shows when the outside of the stem
appears normally green and healthy. Microscopic sections
demonstrate that the diseased condition is caused by the pres-
ence of the Fusarium stage of the fungus which develops
270 CONNECTICUT EXPERIMENT STATION REPORT, I905.
vigorously in the vascular bundles, more or less completely fill-
ing the water-carrying ducts and causing disease of their walls
and the surrounding tissues. The fungus even penetrates
eventually into the bundles of the leaf petioles. Thus the water
supply of the leaf is gradually cut off and the blade finally dies.
These wilt fungi apparently develop to a certain extent on
decaying rubbish in the ground and thus become more trouble-
some from year to year if the land is used consecutively or con-
tinuously for plants liable to infection. In some cases, as
unquestionably with the tomato wilt, the seeds from diseased
plants may carry the trouble and serve as a means of infection.
The continued use of the same soil in hot beds favors the
establishment of the fungus there, when it becomes a means of
infecting the young plants of tomatoes and egg plants. Egg
plants, especially when transplanted to apparently uninfected
fields, often suffer seriously, even though they showed no sign
of the disease in the young plants transferred from the hot-bed.
All these points must be taken into consideration in combatting
wilt troubles. Spraying, because of the infection of the plants
through the underground parts, is of little use. Apparently
soil treatment with chemicals will usually be of little practical
value though based on good theoretical grounds. Orton was
successful, with cotton, in rearing plants that were wilt proof
through selection of wilt resistant individuals in the infected
fields.
ONION, Allium Cepa.
Brittle, Fusarium? Plate XVII, a. Early in June, 1905,
the writer, with Dr. Britton, examined an onion field owned by
Mr. Burton W. Bishop of Guilford to determine the cause of
a disease which is a serious menace to the onion industry in
that region. According to Mr. Bishop, at least one hundred
acres of desirable onion land in the vicinity of Guilford are not
available for growing onions because of this trouble. It usually
starts in some section of a field and spreads in area from year
to year, as the onions are generally grown continuously on the
same land. In Mr. Bishop's field the disease had appeared the
year before near a stone fence and this year was occupying a
considerably larger area. In a neighbor's field the trouble
apparently started from a spot on which a manure pile had
NOTES ON FUNGOUS DISEASES FOR I905. 2/1
recently stood. A report from Mr. Bishop after the onion
season was over showed that the disease did not progress much
later in the season, thus indicating that it is chiefly injurious
to the young plants. At the time of the visit the onions in the
main part of the field examined were several inches high and
well beyond the dampening off stage. In the infected areas
they averaged much smaller and the stand was very poor. Mr,
Bishop stated that the weeds in these infected areas usually
made a poor growth, but this was not evident, at this time, to
the writer.
One of the most general characteristics of the disease is the
brittleness of the onion leaves, from which character the disease
takes its name. Another very evident character is the peculiar
curling of the leaves of some of the plants. In exaggerated
cases these leaves had developed spiral coils of two to three
turns, as is shown in the illustration. Frequently the leaves
are unevenly thickened or constricted and show somewhat
indefinite yellowish spots. The general appearance of the plants
suggested that possibly the disease resulted from insect injury
of some kind, but neither Dr. Britton nor the writer could find
any evidence to support this theory. Neither was there any
evidence of a fungus attack on the parts above ground.
Usually the roots appeared normal when the plants were pulled
up and later examination in the laboratory showed no sign of
any external fungus at work on them. However, when the
plants were taken very carefully from the ground without break-
ing off the smaller roots, examples were found in which some
of the roots, especially toward the extremities, showed slight
irregular swellings, and these roots were more brittle than nor-
mally but otherwise appeared perfectly healthy.
Microscopical sections of these roots, even in places not •
enlarged, showed the presence of an internal mycelium of some
fungus. The m3^celial threads were most evident in the inter-
cellular spaces around the parenchymatous cells and not infre-
quently sent conspicuous irregular branches into these, causing
plasmolysis of their protoplasmic contents, but, so far as
observed at this stage, no evident injury to the cell walls.
Apparently the presence of the fungus caused an unusual local
multiplication of the parench3^ma cells, resulting in the irregular
swellings of the roots. No sign of the mycelium was found in
2/2 CONNECTICUT EXPERIMENT STATION REPORT, I905.
the tissues above ground even when their malformation was
conspicuous. Probably this injury resulted in some way from
the stimulating or irritating action of the mycelium in the roots.
Whether later in the season the fungus penetrated into the leaf
tissues or caused further disease of the roots was not deter-
mined. Specimens of the infected onions left exposed for
a few days in a moist chamber developed growths of several,
apparently saprophytic, fungi, but no special growth showed on
the enlarged roots. The most conspicuous of these external
fungous growths was that of a species of Fusarium.
Soil from an infected field was brought to the Experiment
Station greenhouse and placed in two boxes and a third box was
filled with the soil used in the greenhouse. Onion seed was
planted in each of these, but in one of the boxes of Guilford
soil a heavy coating of a mixture of lime and sulphur was
scattered over the seed in the rows before covering. The young
plants in the untreated Guilford soil dampened off consider-
ably more than in either of the other two boxes, but none of the
plants in any of the boxes developed the peculiar malformation
or brittleness observed on the diseased onions in the fields. The
plants were kept under observation several months. Those
grown in the treated soil made the least growth, as undoubtedly
too much lime and sulphur was used for their best development ;
those in the untreated Guilford soil had a poorer stand but
made a slightly better growth ; while those in the greenhouse
soil made by far the best growth. This might indicate that the
Guilford soil was somewhat deficient in plant food, but Mr.
Bishop states that it had been liberally fertilized.
Everything considered, the trouble seems to be caused by
some soil fungus, possibly a Fusarium, as the mycelium observed
• in the roots could easily belong to such a fungus and it is
known that this genus furnishes several soil fungi. Its devel-
opment in the onion fields seems to be due to the practice of
growing onions continuously on the same land and using
manure as a fertilizer. Probably the disease would cease to be
troublesome if a proper rotation of crops on the land was fol-
lowed, such as corn, onions, rye and clover, using stable manure
only the year the land was in corn and commercial fertilizers
at other times, especially when in onions. Possibly when
infected land is used the trouble could be lessened by isolating
NOTES ON FUNGOUS DISEASES FOR 1905. 2/3
the infected part by a ditch from the remainder of the field and
by the use of chemicals, such as sulphur and lime, in the drills
in the infected area.
PLTJM, Prunus sp.
Bacterial Black Spot^ Pseudomonas Pruni Sm. Plate
XVII, b. In the summer of 1904 Mr. F. L. Perry of Bridge-
port brought to the Station green plums showing a disease,
apparently of bacterial origin, but which was not definitely
determined at that time. The past summer similarly diseased
plums were received from Rhode Island, and at our request
Mr. Perry sent specimens from Bridgeport. This trouble,
apparently, occurs only on the Jananese plums, but may attack
any of the varieties of these, according to growers. The green
plums show conspicuous black-purple spots which are often
slightly sunken. These spots vary in size up to half an inch
in diameter. There are not many on a single plum and these
are usually isolated. The diseased tissue does not extend much
below the skin, so the injury is quite superficial. Usually only
a few plums scattered over the tree show the trouble, but occur-
ring on the green fruit one is apt to fear that later it will
develop into a very serious pest. This does not happen, as
the trouble becomes less conspicuous and vigorous on the
ripening fruit and fails to spread further. Specimens of the
nearly grown but green fruit when placed in a moist chamber
in the laboratory did not show any further progress of the
disease though kept for some time under observation. Cul-
tures made from diseased tissue from the interior uniformly
gave growths of a yellow motile organism, thus showing
bacteria to be the cause.
So far as found by the writer, this disease has been described
only by Erwin F. Smith in short notes (Science, 17: 456-7,
1903, Ibid., 21: 502, 1905) from his extended studies of the
disease, which he found on Japanese plums in Michigan. Dr.
Smith states that the disease also occurs on the leaves form-
ing numerous small water-soaked spots which finally may end
in shot holes. The writer has not had the opportunity to
examine infected trees to see whether the disease affected the
leaves here, but the correspondents have ■ not complained of
injury to these. In the Report of this Station for 1903, page
337, the writer called attention to a bacterial spot of peach
18
274 CONNECTICUT EXPERIMENT STATION REPORT, I905.
leaves about which nothing at that time had been written. The
general appearance of these leaves seems to be similar to that
described by Smith for the diseased plum leaves. No cultures
were attempted from the peach leaves, so it is impossible to
state definitely whether their disease was caused by the same
organism as the plum disease. Smith discovered in his investi-
gations with the plum spot that the bacteria gained entrance
into the leaves and fruit through the stomates and for some time
confined their development to the substomatic cavities. He
also found that the disease was chiefly of meristematic tissue,
which accounts for its failure to progress with the maturity
of the leaves and fruit. While the disease in its present con-
dition is not very serious, one can not assume that it will
remain so since it may spread to other varieties and become more
virulent. Though of bacterial origin, it is quite different from
the bacterial blight that has been found occasionally on the
plum and commonly on the pear, etc., in this state.
RASPBERRY, Ruhus sp.
Grey Mold, Botrytis patula Sacc. & Berl. This fungus was
collected at the Frisbie farm, Southington, in July, 1902, on
the fruiting canes. These were dying prematurely, apparently
from the attack of some fungus. While this fungus was by
far the most conspicuous one found in the stems, it may not
have been the primary cause of the injury, as the cane wilt
fungus, Leptosphaeria Coniothyrium, was also present. The
Botrytis formed a greyish growth which broke out in small sori
on the epidermis, but these were often so closely placed that
they formed a conspicuous felt-like mat, resembling considerably
that of a vigorous downy mildew. The spores are large and
look more like those of the Peronosporeae than they do those
of Botrytis. The fungus is certainly not a typical Botrytis and
possibly does not belong to that genus, but further study with
fresh material would be necessary to determine its exact rela-
tionship, as it is difficult to say from the old material how the
spores are borne. This species was described in 1885 by
Saccardo and Berlese from specimens sent by Ellis from New
Jersey. In the Syll. Fung. 4, p. 25, the host is given as SalLv ( f)
which is apparently S. mistake,* as specimens collected by Ellis
*In the host index, volume 13 of the Syll. Fung., both Salix sp. and
Ruhus strigosus are given as hosts.
NOTES ON FUNGOUS DISEASES FOR I905. 275
at Vineland, N. J., June 28, 1884, and which the writer has
examined, through the kindness of Dr. Underwood, from the
N. Y. Bot. Garci., are labeled "on living red raspberry canes."
Apparently the fungus has been very rarely collected.
SPINACH, Spinacia oleracea.
Leaf Mold, Heterosporium variabile Cke. Plate XVIII, a.
Halsted, of New Jersey, who has issued a bulletin on the fungi
which attack spinach, does not give this fungus in his list, though
he does mention other molds that appear on the old leaves. It
was described originally by Cooke, of England, in Grevillea, 5,
p. 123, in 1877, and the host was given as "languishing leaves
of Spinacia," The specimens collected by the writer were on
leaves of spinach obtained in the New Haven market in January.
Usually only the outer two or three leaves of each head were
attacked by the fungus. These leaveis showed subcircular dead
spots, about a quarter of an inch or less in diameter, which
were more or less densely covered above and also usually below
with a conspicuous olive-black moldy growth. When the spots
were thickly placed the intervening tissue was a sickly yellowish
color and the leaf worthless. Even when the spots were not
so abundant the market value of the spinach was lessened
because of its appearance. The fungus may or may not be a
true parasite, as the writer has often seen spinach leaves in the
fields with spots on them but with no sign of fungous growth.
That it is not a very vigorous parasite was shown by its presence
being limited largely to the older leaves. A species of Alter-
naria which produces a general appearance very similar to this
fungus has also been observed on the older leaves of spinach
in the market.
SaUASH, Cucurhita Pepo.
Downy Mildew, Peronoplasmopara Cubensis (B. & C.)
Clint. The squash is a host not before reported for this fungus
in Connecticut. The appearance of the infected leaves was so
different from that' of the usual hosts that the writer did not
recognize the trouble at the time of collecting it but mistook it
for a bacterial leaf spot. The leaves were thickly covered with
276 CONNECTICUT EXPERIMENT STATION REPORT, I905.
small angular brown spots which were more conspicuous on the
upper than on the lower side and much smaller than those
ordinarily seen on the musk melons and cucumbers. There was
no evident growth of the fungus and the microscopic examina-
tion revealed the presence of only a few conidiophores. The
spores, apparently, averaged smaller than on some of the other
hosts.
STRAWBEREY, Fragaria sp.
Leaf Scorch. About the last of June, 1905, Dr. Britton and
the writer visited Mansfield Bros.' farm at West Hartford
to determine the cause of an unusual trouble of their strawberry
plants. Many of these were drying up and dying. The older
plants suffered more than the younger and the older leaves
before the newer leaves on the same plant. The leaves turned
purplish and then gradually dried up and died. No sign of
insect or fungous work was visible on them and an examination
of the roots and crowns gave no indication of any special pest
as the cause of the injury. The plants suft"ered most where
the matted row method of culture was used. As the early sum-
mer had been unusually dry, the writer finally came to the
conclusion that this was largely responsible for the trouble,
though this injury did not show prominently until the very
dry weather was past. Possibly the trouble was aggravated by
winter injury of the roots and the method of culture, which
was not so well adapted to dry weather.
Powdery Mildew^ Sphaerotheca Humuli (D. C.) Burr.
Plate XVIII, b. This mildew had not been collected in the
state until last June, when Dr. Britton found, at Poquonock, a
few infected plants in a field near a manure pile. It is a trouble,
however, that is rarely reported injurious to the strawberries.
The leaves become covered on either surface, but showing most
conspicuously on the upper, with a mealy white growth of the
fungus. This is the conidial or summer stage and the winter
spore stage is rarely formed on this host.
TOBACCO, Nicotiana Tahacum.
Dampening off, f Sclerotinia sp. Plate XIX, a-b. Several
seed-bed troubles of tobacco have been described by Selby in a
recent bulletin, No. 156, of the Ohio Experiment Station, but
NOTES ON FUNGOUS DISEASES FOR I905. 2/7
apparently the one mentioned here is different from any
described by him. In appearance, Plate XIX, b, the injured
plants were very similar to those figured by Selby for a bed-rot
injury caused by a Rhizoctonia fungus, but examination o°f the
specimens received here did not reveal the presence of this
fungus. The disease showed on the young plants at the base
of the stem as a conspicuous dead area or a complete girdle.
Often the injury was so severe as to cause the death of the plant.
When placed in a moist chamber the infected plants produced
a growth of a sterile white fungus at the injured part. Plate
XIX, a, shows cultures of this fungus growing on potato agar.
These cultures never produced any spores but instead formed
the numerous small sclerotia similar to some of those described
by Smith for the Sclerotinia drop fungus of lettuce, which is
also a soil fungus.
Mr. W. E. Frost of Bridgewater, who sent the diseased
tobacco plants, wrote in part as follows : *Ts there anything
that can be done to stop the rotting of tobacco plants in the seed
beds? Where they rotted last year they are doing so this year.
Can anything be done so that it will not appear in the same beds
another year? Would it be safe to set plants from beds where
there is some rot if the plants appear all right when taken up ?"
Fungous troubles in seed beds are chiefly due to two conditions :
first, keeping the plants too moist by improper watering, insuf-
ficient ventilation or crowding the plants too closely together;
second, fertilizing with manure or using the same soil in the
beds year after year, thereby establishing in these special injuri-
ous soil, fungi. When the trouble is of the second sort, as in
the present case, the soil should be changed or new beds made
and where feasible only artificial fertilizers should be used.
Applications of lime and sulphur to infected soil possibly in
some cases may prove of benefit. In answer to the last question
asked by Mr. Frost, it may be stated that the writer set out
some of the least diseased plants received and these did not
develop the trouble any further and did fairly well during the
whole season. There are some diseases, however, contracted
in the seed beds, as the wilt of egg plants, where the infected
individuals do poorly the whole season.
2/8 CONNECTICUT EXPERIMENT STATION REPORT, I905.
DOWNY MILDEW, Phytophthora Phaseoli Thaxt., OF
LIMA BEANS.
In the Botanical Gazette (18) and the Annual Report of this
Station (19) for 1889, Professor Thaxter, then botanist of the
Station, recorded the discovery of the Lima bean ^mildew, which
he found doing damage in Connecticut. Besides giving a
general and scientific description of the fungus, Thaxter
described and illustrated in detail the parasitic, or summer stage,
but he was not successful in discovering the oospores, or winter
stage. His successor. Dr. Sturgis, also in the Botanical
Gazette (16) and the Reports of the Station (15, 17) added to
our knowledge of the fungus by describing its methods of
infection, especially that accomplished by the aid of insects, and
recorded successful spraying experiments. He, too, failed to
find the oospores, though special search was made for them.
The writer adds, in this paper, his contribution to the knowledge
of the fungus in a description of the missing oospores and of
artificial cultural experiments. Practically all that is known
of the mildew, except its limited distribution, has resulted from
the work of the botanists of this Station. It is fitting, there-
fore, that a detailed account of the fungus, its injury and
methods of prevention, be given in this place.
PARASITIC, OR SUMMER STAGE.
Relationships. The Lima bean mildew belongs to the small
genus, Phytophthora, which is especially characterized among
the downy mildews by the nodular swellings on the conidio-
phores (spore-bearing threads) that mark the position of the
successively developed spores. The genus includes serious
parasitic pests, the most conspicuous of which is the downy
mildew, or blight, of potato. This is the only other species
that occurs in Connecticut. Another species, found in the East
Indies, has tobacco for its host, and a fourth is injurious to
seedlings of beech, Coniferae, etc. One or two other
species have been described recently. Apparently the mildew
of Lima beans is most closely related botanically to the species
that occurs on tobacco.
Distribution. Thaxter first found the Lima bean mildew in
September of 1889 at Hamden, Conn., near New Haven, where
DOWNY MILDEW OF LIMA BEANS. 279
it had been injurious at least two years before his discovery.
In the Report for 1890 (20) he writes: "This mildew (Phyto-
phthora Phaseoli) described and figured in last year's report,
has been again destructive this year and has made its appear-
ance in a number of new localities in the neighborhood of New
Haven. So far as ascertained it extends from New Haven to
Hartford and west to South Norwalk, but has not yet been
discovered outside of Connecticut." So far as recorded, Stur-
gis' work and observations on the fungus were in the vicinity
of New Haven (East Haven, Westville, etc.). The writer's
experience, too, has been limited to this vicinity, though com-
plaint of it has been received from Green's Farms. Probably
the fungus has appeared in Connecticut (in a more or less
conspicuous way) each year since its discovery. Thaxter col-
lected specimens in 1889 and 1890. Sturgis records it as being
injurious "for some years" in 1893 but failed to find it that
year in localities where it had always been abundant; he also
records it for the years 1897 and 1898 and states it was prevalent
for two or three years previous. Rorer collected specimens in
1901 and the writer made collections in 1902, 1903 and 1905.
Outside of Connecticut the fungus was first reported in New
Jersey by Halsted (4) in 1897, and he has found it several
times since in the same state. It was also reported about this
time by Speschnew (13) from Tiflis, Russia, and has been found
by other Russian botanists. Smith (12) states it was injurious
in 1903 in Delaware. So far as the writer has learned, these
are the only published records of distribution. Thinking that
possibly it had been noticed but not reported in other of our
eastern states, where the chances for its introduction and devel-
opment seemed favorable, information on this point was asked
of the Division of Vegetable Pathology and Physiology of the
U. S. Department of Agriculture and of the Experiment Station
botanists of fourteen states, chiefly those bordering on the Atlan-
tic coast. Letters received from these showed that the mildew
had not been observed in any other states than those mentioned
except in two cases. Mr. Stewart, of the Geneva Station,
N. Y., reports the receipt of specimens from Long Island once
each in 1904 and 1905, and Mr. Woods, of the Division of Vege-
table Pathology and Physiology at Washington, states that the
fungus was very injurious in Frederick county, Maryland, in
1905.
280 CONNECTICUT EXPERIMENT STATION REPORT, I905.
Injury to host. So far as reported, only the Lima bean,
Phase olus lunatus, is subject to the attacks of this mildew. The
writer has seen it on both the pole and dwarf varieties, though
rarely on the latter. The dwarf varieties are not usually grown
on a commercial scale in Connecticut and probably do not pre-
sent so favorable conditions, as regards moisture, for the spread
of the fungus, though Sturgis has reported a case where they
were severely injured. The pods are the parts of the host most
subject to attack, but the fungus also occurs to a limited extent
on the young leaves, vines and flowers.
The growth of the fungus on the pods, Plate XXII, a-b, is
often very conspicuous, forming a dense pure white felt of the
conidiophores in irregular patches, or sometimes spreading over
the entire surface, on one or both sides. Both Thaxter and
Sturgis have noted that the mildew often at first is present only
on one side of a pod, and the latter states that this is usually
the side furthest from the vine and least protected by the
leaves. The injury to the pod generally shows but little beyond
the area covered by the fungus, though the green of the healthy
tissue may be separated from the diseased by a more or less
distinct purplish border. As a pod becomes more and more
severely injured it ^yilts and gradually dies, shriveling up in
the irregular form shown in the illustration. The fungus event-
ually penetrates into the interior of the pod, causing the tissues
to become sunken, and the mycelium may enter the seeds. Many
pods are attacked so vigorously in their infancy that they are
killed outright and others are injured so they never mature.
The injury to the large pods varies with the abundance of the
fungus, but even when not preventing maturity of the seeds it
may still affect their market value by injuring their appearance.
The mildew opens the way for further injury to the pods and
seeds by other fungi, so that quickly following its prime devel-
opment there appear such fungi as Fusarium, Alternaria,
Cladosporium, etc. The growths of these eventually discolor
the pure white of the mildew.
The attack of the fungus on the flowers is not usually very
conspicuous, though it is through insect visitation to these, as
shown by Sturgis, that the infection of the young pods often
takes place. So, too, the leaves, petioles and vines are gen-
erally not much injured and apparently are infected only
DOWNY MILDEW OF LIMA BEANS. 28 1
in their young state. The infected leaves often show an
irregular injury of the tissues with more or less of a purplish
discoloration, especially on the veins, and there is no very evident
growth of the fungus showing on them. See Plate XXI, b.
Financial loss. In this state a few Lima beans are usually
grown by each farmer for home consumption and most garden-
ers grow the pole varieties in quantities for the market. They
are probably raised most extensively around New Haven, though
each large city has more or less grown in its vicinity. The
largest grower in the state, A. N. Farnham of Westville, often
plants twelve or more acres and sometimes most of these are
in a single large field. The financial loss due to injury by the
mildew comes chiefly on the market gardeners and is greatest
in those localities where the beans are grown extensively.
Thaxter's statement, based on his observations at Hamden, that
the mildew "bids fair to become the most serious obstacle yet
encountered in the cultivation of this vegetable," especially in
the Atlantic seaboard states, was not exaggerated. Sturgis
wrote that "during the summer of 1897 the conditions were
such that in many places the effects of the fungus have been
most disastrous." In 1898, in a number of counts in a certain
field, he found that the percentage of pods attacked by the mil-
dew varied from 36 to 53 per cent, of the total number pro-
duced during the season. The writer's observations on the
disease began in 1902, when the fungus did considerable dam-
age, especially in the lower, more moist places in the fields.
During the next two years there was comparatively little injury,
but in 1905 the loss caused by it was the greatest since 1897.
In one of the largest fields in the state, the grower estimated
that the yield was cut down about one-third by this pest.
Halsted (4) states that the mildew was so serious in New
Jersey in 1897 that "few or no pods were picked from some
of the fields." He also reports numerous complaints of it in
that state in 1902. Smith (12) records the mildew as injuri-
ous in Delaware in 1903 ; and Woods in a letter to the writer
states that, in Frederick county, Maryland, in 1905, "it is said
to have destroyed from 25 to 90 per cent, of the crop."
Relation to zveather. The prevalence of most parasitic fungi
is largely influenced by the character of the weather, particu-
larly in regard to moisture. This is especially true of the
282 CONNECTICUT EXPERIMENT STATION REPORT, 1905.
downy mildews. An abundance of rainy or cloudy weather at
certain periods of the year determine whether or not these
troubles will be injurious. July, August, and to a less degree
September, are the months in which unusual moisture develops
the downy mildew of the Lima bean, just as it does the downy
mildew, or blight, of the potato. So far as yet ascertained, the
middle of July is the earliest that the Lima bean mildew has
been found in this state and frequently it does not appear
until the middle of August. After its appearance it can be
found more or less abundant, according to the weather, up to
the time the vines die. Halsted (6) notes the fungus as late
as October 24 on green pods, after the leaves had been killed by
frost, and the past year the writer collected it in several fields
on October 4 under the same conditions. Sturgis reports, how-
ever, that in 1897 "for some reason not wholly clear, perhaps
because of lessened insect activity, the mildew ceased spreading
about September loth."
From the published data it seems quite certain that trouble
from the mildew may generally be expected in very moist years.
Halsted (5), writing on this point, says: "The year 1897 had
its counterpart in that of 1889. During the past ten years there
have been in the Eastern States two Julys noted for their
excess of rainfall (1889 and 1897). ... In connection
with what has been said above concerning the influence of
copious rainfall upon the unusual development of the potato
rot, it is in order to report that another member of the genus
Phytophthora [the Lima bean mildew] has been complained of
bitterly during the season of 1897. . . Particular empha-
sis is placed upon the date of the discovery [1889] ^^*^ the fact
that it was very abundant at the time it was taken, because
that was the year in which the three months of July, August
and September gave a total rainfall of 27.33 inches for New
Jersey and presumably as wet in Connecticut; which is 9.54
inches more than the average of those three months for the
past ten years." Besides in 1889 and 1897, the mildew was
unusually abundant in 1902, which year was characterized by
cold damp weather in July and August, and again in 1905, which
though dry previous to the middle of August was rather
moist the remainder of the month and during the first part of
September,
DOWNY MILDEW OF LIMA BEANS. 283
The middle Atlantic seaboard states apparently offer the
best conditions for the development of the fungus, and as it has
spread into most of these, there may be expected increasing
trouble from the pest in their market garden districts in years
with very moist weather during July or August. Not many
Lima beans are grown in New England north of Connecticut.
In the drier middle and western states less injury may be
expected should the fungus become introduced, except possibly
in localities affected, as to moisture, by the Great Lakes.
Methods of distrihution. The means by which the fungus
spreads over the vines after it once gets started in a field and
presumably by which it is carried to some extent from one field
to another, have been discussed somewhat in detail by Sturgis.
He found that both insects and wind were important agents
in its distribution. Rains also aid greatly by washing the
spores from the infected parts over the same plant.
Concerning insects as agents of distribution, we quote from .
Sturgis (15) as follows:
"The occurrence of the mildew on the pods at a very early stage of
their growth, led to the supposition that insects were responsible in a
measure for the spread of the fungus. Examination of the flowers
served to confirm this supposition, and a few words regarding the struc-
ture of the bean flower will explain how infection takes place. The
conspicuous portions of the bean flower consist of an upright petal known
as the standard; two narrower petals, distinct, projecting forward below
the standard and known as the wings; and two petals in the form of
a closed, spirally coiled tube occupying a position between the standard
and the wings, and called the keel. (Fig. 8,^) At the base of the
keel is the ovary or young pod surrounded by the stamens and prolonged
upwards into the style. The long stamens and style are completely
enclosed in and protected by the keel. Under such conditions cross-
fertilization would seem to be impossible, especially as the pollen is
shed abundantly from the anthers which are borne upon the stamens in
close proximity to the upper portion of the style, and neither the stigma
nor the anthers appear beyond the end of the tube in which they are
enclosed. But the wings form a convenient resting place for visiting
bees in search of nectar, and in case a bee lights upon them his weight
deflects them and at the same time draws the keel down and backward,
thus causing the stigma and the hairy portion of the style covered with
pollen to protrude from the mouth of the tube. (Figs. 8,^'^) As the
insect plunges his head into the flower, the stigma and pollen-laden
style come into contact with his abdomen and cross-fertilization is
assured by subsequent visits to other flowers. But fungous infection is
284 CONNECTICUT EXPERIMENT STATION REPORT, I905.
assured with hardly less certainty, provided the bee has previously had
contact with the spores of the fungus. In that case we should expect
to find the first attack of the fungus at the two points where the bee,
in his search for nectar, touched the more moist and delicate tissues of
the flower; viz. on the style and at the base of the ovary or pod. A
large number of flowers was examined and this supposition was
t_V____d.
A—f.
Fig. 8. Showing details of bean blossom with reference to infection with
mildew by bees. i. Parts of blossom: a. standard, b. keel, c. wings. 2.
Showing how the weight of a bee alighting on the wings causes protrusion
of style, d. 3. An enlarged keel in cross-section, showing enclosed pistil
with young ovary or pod at its base, e. 4. Pistil showing growths of mil-
dew (f.) at base and apex of the young pod resulting from spore inoculation by
bee visitation during blossoming period. (1-2 after Gray; 3-4 after Sturgis.)
strikingly confirmed. The mildew was found in many of the flowers,
and in every case it occurred on the spots above mentioned and nowhere
else. (Fig. 8, *) It seems certain, therefore, that the spread of this
mildew is largely due to the agency of insects, particularly of bees, and
this view is further confirmed by the fact that in the case of young pods
the mildew almost always appears first at the base or tip and very rarely
in the middle."
DOWNY MILDEW OF LIMA BEANS.
285
The influence of wind on the distribution of the fungus in
a field is shown by the following account, also quoted from
Sturgis :
"The Lima beans on the
Station grounds are on high
land composed of a light
sandy soil, and have never
been affected with mildew.
The rows run east and west.
Directly south of them at a
distance of about one hun-
dred feet, but separated from
them by a pile of lumber and
a few trees, are two rows of
bush Limas running north
and south. On August 14th,
when the mildew had been
abundant in the neighbor-
hood for a month or more,
the Station vines were exam-
ined and found to be entirely
free from the fungus. A
few mildewed pods were
brought from a distance, and
the spores from one of them
were rubbed and dusted on
the surface of a sound and
nearly ripe pod at the east
end of each row of the pole
Limas. Within a few days
the mildew made its appear-
ance on the infected pods,
and from this point of van-
tage, the prevailing winds at
the time being from the
northeast and north, it swept
down both rows and in two
weeks the whole patch was
completely mildewed. The
spores had also been carried
over a distance of one hun-
dred feet to the bush Limas,
and the mildew, beginning
at the north end of the rows,
that is, at the point nearest
to the pole beans, spread ^^^ ^ Details of conidial stage,
rapidly down the rows. It (After Thaxter.)
286 CONNECTICUT EXPERIMENT STATION REPORT, I905.
is evident then, that spores placed upon the surface of a sound Lima bean
pod were enabled to start the disease, which thereupon spread with
great rapidity in the direction of the prevailing wind."
Microscopic structure. Having considered the more general
character of the fungus and its environmental factors, let us
proceed to a study of its minute structure as revealed by the
microscope. For a preliminary account we can do no better
than to give Thaxter's (19) description:
"Examination of a section of the diseased tissue shows it to be
penetrated by the irregular branching hyphse of the fungus [mycelium]
which run between the cells and, collecting in the air spaces beneath
the breathing pores, push out through them into the air (Fig. 9,^") in
such numbers that the latter are completely obliterated. These hyphse
(Fig. 9,'"), just at their point of exit from the breathing pores, are
usually slightly swollen and give rise to one or more branches [conidi-
ophores] which grow almost vertically into the air, and, taken together,
produce the white woolly appearance already mentioned as characteristic
of the disease. These vertical branches may themselves be once dicho-
tomously branched, that is give rise to two branches, forming a more
or less symmetrical fork; while at their tips they swell out into the
large, terminal, oval conidial spores represented in the figure. A pecu-
liarity of the genus Phytophthora consists in the fact that after a spore
has been produced at the apex of .a hjnpha, the hypha continues to grow
at the point where the spore is attached, pushing it to one side if it
has not already fallen off, and soon swelling into another spore. This
may be repeated several times, the points where spores have been pre-
viously formed being marked by successive vesicular swellings (Fig.
9,"^)."
The myceliiim is similar to that usually formed by the dovvmy
mildews. Its hyaline threads, Plate XX, 1-6, are more or less
branched, are occasionally somewhat irregular in shape and
have a comparatively thin cell wall which on staining with chlo-
roiodide of zinc shows the presence of cellulose. They are
chiefly S'JP- or occasionally even gix. in diameter. The contents
at first completely fill the threads and consist of a very homo-
geneous protoplasm, or this may also contain numerous oil
globules of varying size. As the threads advance in their
growth they often become empty in their older parts and also
rarely develop septa with the recession of the protoplasm. The
writer has not studied the special haustorial branches that push
directly into the cells in search for food, and Thaxter simply
states that the mycelial hyphae rarely penetrate the cells of the
host by irregular haustoria.
DOWNY MILDEW OF LIMA BEANS. 28/
The conidiophores of this mildew are much longer than those
produced by the potato mildew. In the figures shown here
from Thaxter, Fig. 9, ^®' ^°' the young conidiophores have not
reached their full length. In fact they usually become so long
and lax that they form an interwoven mat rather than erect
distinct threads. They also differ from the conidiophores of
the potato mildew (which give off two to several simple
branches along the apical third of their length) in that they are
simple or more rarely dichotomously branched, usually near
their base. Some conidiophores were found having over a
dozen swollen nodes, thus indicating the formation of as many
spores, but usually they have less than half a dozen, which may
be scattered or grouped toward the terminal end. Occasionally
it is difficult to detect any nodal swellings on a thread. From
these statements it is seen that the conidiophores are not so
differentiated into spore-bearing organs as in the potato mil-
dew. For this reason it is hard to tell whether the white
matted growth that covers the exterior of the pods is com-
posed entirely of conidiophores or partly of mycelium from
which the conidiophores develop. The latter, however, are
often found growing directly from the stomates in clusters
which sometimes contain a dozen individuals but more fre-
quently about half that many. Thaxter does not give the length
of the conidiophores and it is difficult in the old matted groAvths
to separate out single ones for measurements. Specimens were
measured that varied from 300 to 475 /a but these were pro-
bably not extreme lengths. In an examination of artificial
cultures, one fruiting thread that was traced measured over
1200/A in length. The diameter of the conidiophores is usually
about 5 or 6/x,, rarely 8.5ft, at their lower end, and they taper
to about 2.5 or 3ft at the apical extremity. The swollen nodes
generally vary from 4 to 6ft in width. At first the conidi-
ophores are filled with protoplasm, but as spore production pro-
ceeds their contents are limited to the distal end and finally they
may become entirely empty. Their walls are thicker than those
of the mycelial threads and give a stronger reaction in the test
for cellulose, as do also the spore walls. Very rarely septa
are seen in the empty conidiophores.
The conidia, or spores, of the Lima bean mildew. Fig. 9, ^^' ^^'
are similar to those of the potato mildew, but larger. The
288 CONNECTICUT EXPERIMENT STATION REPORT, I905.
spores of the latter vary from 17 to 35)U, in length by 11 to
20 fji in width, while those of the Lima bean mildew are chiefly
28 to 42 /a; in length by 17 to 27/A in width, and Thaxter records
some even ^O/x in length. They are hyaline, elliptical to
chiefly ovoid in shape or rarely even broadly ovoid to subspher-
ical. The papilla of dehiscence is very evident at their apical
end, and when shed from the conidiophores the basal end is
usually marked by a short hyphal plug showing the point of
detachment. Protoplasmic contents fill the spores usually
without special differentiation, though sometimes at germina-
tion faint areolations appear.
Germination of spores. The spores do not germinate readily
unless perfectly fresh. The germination of such spores placed
in a drop of water in a Van Tiegham cell takes place in a few
hours and can be easily watched under the microscope.
Thaxter's excellent description of their germination is as
follows :
"The germination takes place in two ways. In the one case a single
hypha of germination is produced, which may enter the host plant
directly or give rise to another, or secondary spore like itself (Fig. 9, ^^' ^")
which germinates in its turn like the ordinary conidia. In the second
case, which is by far the most common, the content of the spore becomes
very faintly lobular, as shown in Fig. 9, '^ and suddenly and rapidly
begins to make its exit, through the ruptured apex of the spore, Fig. 9, ^*
.in the form of a continuous chain of spindle-shaped bodies, consisting
of naked protoplasm; the orifice alternately expanding and contracting
as each body is, as it were, squeezed out by the pressure from within.
In some cases the whole content of the spore makes its exit thus,
the chain winding itself into a round or oval mass above the apex of
the conidium as in Fig. 9, ^^. Usually, however, the chain breaks in the
course of its discharge and almost instantly a rapid motion begins, at
the point of separation, which draws the spindle-shaped bodies suc-
cessively apart. The motion is due to a slender thread or cilium, drawn
out by the pulling apart of the narrow zone connecting two adjacent
bodies, and the rapid vibration of this thread gives rise to the motion
just mentioned. The spindle-shaped bodies, as soon as they are free,
move irregularly for a moment, changing their shape the while, till they
become contracted, the two extremities being drawn together on one
side towards a small clear spot, usually present in bodies »of this nature,
so that in one view the outline is slightly crescent or bean-shaped
(Fig. 9,^°). After or during this change of shape the motion of the
cilia becomes very rapid, and the bodies, which are known as zoospores,
dart away in the surrounding water. After swarming for a certain
time, usually about half an hour, the zoospores come to rest, assume a
DOWNY MILDEW OF LIMA BEANS. 289
Spherical shape, swell considerably, become surrounded by a thin cell
wall and very soon begin to germinate (Fig. 9, ") by giving rise to a
hypha which makes its way into the tissues of the host plant, thus
infecting it with the disease. The whole process, owing to the minute
size of the zoospores which are less than lofo^w of an inch 'in diameter,
may take place upon the moist surface of a leaf or other portion
of the host plant, the thinnest pellicle of water being sufficiently deep
for them to swim in. The usual number of zoospores formed from
spores of average size is about fifteen, so that each spore may give rise
to fifteen distinct points of infection." ,
Perpetuation of the fungus. The zoospores just described
are very short Hved, lasting so far as known but a few hours.
The conidial spores, too, are of a temporary nature, retaining
their power of germination but a comparatively short time even
under favorable conditions and in dry weather perishing in a
few days or even hours. The conidiophores and mycehum are
more persistent, but as the Lima bean is an annual it is impos-
sible for the mycehum to live over the winter (except in the
seeds) as a dormant parasite. It may be thought, possibly,
that the mycelium survives in the rubbish of the diseased beans
and in the spring as a saprophyte gives rise to the conidial
spores. This, however, is contrary to the known habits of the
downy mildews and against all evidence that the writer can find
after a careful examination of this species. Invariably the
Lima bean mildew suffers in development by the decay of the
infected pods and is at a decided disadvantage in competition
with bacteria and saprophytic fungi that follow in its wake.
So far as observed, it then gradually ceases to form conidial
spores and fails entirely to spread further, at least in this spore
stage. If the mycelium does develop as a saprophyte, which
we doubt, it would most likely produce an entirely different kind
of spores — the oospores.
Sturgis made some observations and experiments to deter-
mine if the mildew survived the winter in the refuse of a mil-
dewed crop by means of "resting spores, a perennial mycelium
or any other form." In his search through such material that
had been kept out doors over winter he failed to find "any trace
of a vegetative or reproductive body which could be even
remotely associated with the Phytophthora causing the mildew."
Seeds taken from this refuse and planted all rotted but one.
which produced a perfectly healthy plant. The refuse was used
19
290 CONNECTICUT EXPERIMENT STATION REPORT, I905.
as a mulch on ground at the Experiment Station and planted
with Lima beans, but the beans came up through the mulch with-
out apparent infection and remained free from the mildew
until near the close of the season, when some did appear. In
judging of the results of this experiment one must remember
that Sturgis found no sign of oospores in the refuse he used
and presumably they did not occur in it abundantly if at all.
The writer, however, has found them recently under similar
conditions though mostly in poor shape due to attack of other
fungi on them before they were matured. It must be taken
into account, too, that the mildew did appear on these beans
toward the end of the season, but possibly it was brought in
by insects, though the Experiment Station grounds are far from
any other place where Lima beans are commonly grown and
the mildew has rarely appeared on beans planted there. Stur-
gis evidently considered the experiment largely a failure
because "diseased plants" were not produced from diseased
seed and because the mildew did not appear out of season and
in abundance from primary infections.
In a preceding paragraph it was stated that as the Lima
bean was an annual plant it was impossible for the parasitic
mycelium to be carried over from one year to another by it
except in the seeds. We believe this is sometimes done and
in the report of the Station for 1903, p. 308, expressed the
belief that it was the ordinary way the fungus perpetuated
itself. From our examinations of the past year we now know
positively that the mycelium does often penetrate from the
pods into the seeds. If the pod is badly diseased the seeds
are destroyed, or at least injured so they will not germinate,
by this and other fungi that follow it. There are, however,
probably all gradations between seeds destroyed and those in
which the mildew barely gains entrance. Experiments made
by the writer go to show that diseased seeds that germinate do
not produce "diseased plants" ; that is, the mycelium does not
pass from the seed into the young plant and produce a con-
spicuously injured plant from which the fungus is eventually
spread by conidial spores to other plants. There is reason,
however, for believing that the dormant mycelium may be
carried over the winter in the seeds (just as is the potato
mildew in the tubers) and that on the living tissue of the
DOWNY MILDEW OF LIMA BEANS. 2gi
seed when planted it may form a few of its conidial spores (as
can the potato mildew on the cut surface of the seed tuber) or
that possibly in some cases a delayed production of the
oospores takes place in the cotyledons. In either case the
writer believes that the primary infection of the plants takes
place by the germination of the conidial spores or the oospores
into zoospores and these latter infect the parts of the plant
brought into contact with them in the moist earth. That the
mycelium is sometimes present in apparently sound seed is
shown by the following case, in which nearly matured seeds
were taken from diseased pods in the fall and placed in a damp
chamber on moist cotton. These seeds were taken away from
the diseased part of the pods and to the naked eye showed
no sign of disease or evidence of the mildew. Yet in less
than a week some of them v/ere developing abundance of
oospores in their tissues and some few had a slight conidial
development on the outside. The only point not determined
was how long the mycelium would have lived had the seeds
been dried out ; or in other words, if it could have passed the
Vv'inter in them and then have gone through the same develop-
ment when they were planted in the ground in the spring.
Mention has been made several times of oospores. Such
spores are of an entirely different character from the temporary
conidial spores. They are thick- walled and are usually pro-
duced by the mycelium within the tissues of the host. They
do not, as a rule, germinate when formed but are for the pur-
pose of carrying the fungus over the unfavorable winter period
and on germinating the next season produce the primary infec-
tions of their hosts. Oospores are characteristic of the downy
mildews, but until discovered recently by the writer were not
known for the Lima bean mildew. Let us now pass to a
consideration of this stage of the fungus.
OOSPORES, OR WINTER STAGE.
Where and when found. Although Thaxter, Sturgis and
the writer made especial search for the oospores they escaped
notice until September, 1905, at which time the mildew was
unusually abundant in the region of New Haven. There may
be two reasons why the oospores were not found before ;
namely, either they did not occur commonly or they were
292 CONNECTICUT EXPERIMENT STATION REPORT, I905.
not looked for at the proper place and time. The latter reason
more likely explains the failures to find them. Judging from
the experience of the past year, the oospores should be looked
for toward the end of the season and in the seeds of the pods
badly infected with the mildew. Sturgis searched especially
for them in the pods and the decaying rubbish. The writer
also looked for them chiefly in these places and in fact actually
collected pods in 1902 which a recent examination shows had
immature oospores in the seeds that escaped detection. Not
all of the seeds from infected pods contain oospores and there
is no sure way of determining whether they are present or not
except by microscopical examination. Often after the myce-
lium of the downy mildew penetrates from the pods into the
seeds, the mycelia of other fungi, especially that of Fusa-
rium, develop so abundantly as to seriously interfere with the
further growth of the Phytophthora. Frequently, too, the
mycelia of these other fungi form the more conspicuous grov/th
both outside and inside of the seeds. Plate XXI, a, shows in the
lower row several dried seeds, containing oospores, that were
taken from badly mildewed pods. So far the oospores have
been found in the seed coats and cotyledons of the seeds and
to a limited extent in the tissues of the pods, but not in the
leaves or the stems.
If the oospores generally occur only in those seasons when
the mildew is unusually abundant, it has occurred to the writer
that this might be explained on the supposition that there exist
two mycelial strains of the fungus, possibly sexual in nature,
and that the production of oospores can only result when these
strains occur together on the same pods. Naturally a season
very favorable for the spread of the fungus would multiply
the chances of these occurring together. This idea of dis-
tinct mycelial strains is discussed further in this report in the
following article dealing with the potato downy mildew, where
are given the writer's reasons for believing that such strains
may exist among the downy mildews, as has recently been
demonstrated for the related family of the Mucoraceae.
Description of oogonia, etc. The downy mildews, or the
Peronosporeae as they are called scientifically, have a character-
istic oosporic stage which has been observed for many of
the species and is supposed to exist for all. One of the chief
DOWNY MILDEW OF LIMA BEANS. 293
functions of these spores is to carry the fungus over the
unfavorable winter period. The oospores differ essentially in
structure from the temporary conidial spores in that, as resting
spores, they have thick walls, and are formed singly inside
• a special envelope called the oogonium, and further differ from
them in origin in that they are the result of the conjugation
of differentiated sexual branches of the mycelium developing
usually within the tissues of the host. The male cell of the
mycelium is known as the antheridium and after its contents
are emptied into the special female cell, the oosphere (immature
oospore), it often withers away.
The characters of the oogonia, oospores and antheridia of
the Lima bean mildew, as found by the writer, are as follows:
Oogonia (Plate XX, 22-25) inter- or intracellular in seed coats
or cotyledons of seeds, occasionally in tissues of pods and
more rarely imbedded in mycelium on surface of seeds and
pods, with rather thin scarcely folded walls loosely enclosing
oospore, at first hyaline or slightly tinted but finally reddish
brown, subspherical, chiefly 23-38/1^ in diameter. Oospores
(Plate XX, 22-25) spherical or sometimes subspherical, with
apparently smooth and moderately thick walls (2.5-4)0,, chiefly
3/A in thickness), hyaline or light yellowish, 18-26;"., chiefly
19.5-22.5 /A in diameter. Antheridia (Plate XX, 8, 9, 12- 17b)
temporary, hyaline, variable, sometimes irregular but chiefly
ovoid to ovate, usually applied to oogonia near their place of
attachment to the mycelium, chiefly 8.5-11.5/* in width by 14-17/x
in length.
Development of oogonia, etc. It is not easy to make out
exactly the stages of development of the oogonia even from
living material. This is because the mycelium forms a matted
growth within the tissues, often obscuring details. The very
general notes given here were obtained partly by teasing into
fine bits pieces of the seeds known to contain oospores and
exiamining this material under the microscope and partly from
microscopic examination of cultures of the fungus grown on
artificial media in test-tubes, though some fixed and stained
sections were also prepared for examination. No attempt was
made to study the cytological phenomena. Apparently when
the oospores are to be formed the mycelium becomes more
abundant and is often crowded into matted growths of threads
294 CONNECTICUT EXPERIMENT STATION REPORT, I905.
which are more variable and irregular iii shape than normally.
The mature oospores, therefore, are likely to occur more thickly
in certain places rather than to be scattered uniformly in the
tissues or cultures. So far as could be determined the anthe-
ridia and oogonia are developed on distinct mycelial threads.
It was not possible to trace these threads far, as the mycelium by
the tearing apart is more or less torn, but also it becomes less
distinct on the differentiation of these organs, through loss of
contents. These fertile threads possibly ultimately have origin
on a common mycelium, but more probably they represent dis-
tinct mycelial strains mixed together whose combined presence
is necessary for the production of oospores. The writer is
inclined to the latter view, but was unable to determine any
very distinctive characters by which an antheridial developing
mycelium can be told from that bearing oogonia, if such really
exist. Very often the mycelial threads had swollen places in
them (Plate XX, 4) as if these might be tentative antheridia
but which because of the absence of oogonial contact had run
out again into threads, perhaps developing similar swelling fur-
ther on. It seemed to be true, however, that the antheridia are
not usually entirely differentiated on the thread until after con-
tact with the oogonium. Likewise there were not found many
isolated young swollen cells that represented the early stages
of the oogonia. From this one would expect that, if there be
distinct strains, their mycelia would not show, when grown
separately, any development of antheridia or oogonian but
would both form conidiophores. This would agree with
DeBary's statement that, 'Tn all known Peronosporeae and
Saprolegnieae the antheridia are not formed until after the
extremity of the branch which supports them, and from which
they are afterward separated by a septum, has attached itself
to the oogonium and this attachment takes places in the early
stage of both organs."
In a preceding paragraph the mature antheridia were
described. They are formed as a swollen cell (Plate XX, 12b)
at the end of a mycelial thread or a short mycelial branch as cir-
cumstances determine, so that there are no characteristic anthe-
ridial threads. A basal septum (Plate XX, 14b) soon separates,
the swollen end of the mycelial thread into a distinct terminal
cell, the walls of which remain thin. Usually the contents of the
DOWNY MILDEW OF LIMA BEANS. 295
antheridia did not seem to be so sharply marked off from the
cell wall as those of the oogonia, often appearing empty
because of this lack of contrast. This was probably because
oil drops are not so prominent a constituent as in the oogonia.
Often after the antheridia are cut off the threads bearing them
are empty of contents and difficult to trace any distance. Some
of the antheridia showed, when isolated from the oogonium,
a prominent protuberance (Plate XX, 8) but nothing was
seen like a distinct fertilization tube which penetrated into the
oogonium and through which the contents were emptied into
it, as has been described for some species.
The oogonium also starts as a swelling (Plate XX, loc) at
the end of a mycelial thread or a short branch or in some cases is
intercalary. It gradually enlarges and assumes a subspherical
shape. It is thin-walled, filled with protoplasm and oil drops,
and after empt}dng the thread from which it originates of the
contents is separated from this by a septum (Plate XX, 13c).
Usually before the oogonium has reached large size a young
antheridial branch has reached it and the antheridium is
formed at the base of the oogonium, that is, where it is joined
to the mycelial thread. Soon after the application of the
antheridium the oogonium reaches full size and a further
step in its development appears in the transfer of its
principal contents into a central denser mass, the ooplasm
(Plate XX, 15, 16), which a less conspicuous marginal peri-
plasm surrounds. This central ooplasmic body is soon further
marked off by the formation of a thin limiting wall and is then
known as the oosphere (Plate XX, 19). Though not observed,
presumably by this time the antheridial contents have passed into
the oosphere by means of a fertilization tube. From now on
the contents of the oosphere show changes of development the
character and sequence of which were not definitely made out.
At the same time the wall of the oogonium becomes slightly
thicker and eventually has a reddish brown tint. The periplasm
does not seem to be prominent but probably assists in the
formation of the wall of the oospore. This gradually thickens
until 2.5 or 3/A thick (Plate XX, 22) and is uniform, smooth
hyaline or slightly yellowish tinted and consists of a single
evident layer, but outside of this the periplasm apparently forms
an amorphous envelope which probably serves as a protection
296 CONNECTICUT EXPERIMENT STATION REPORT, I905.
against absorption of water out of season. A large oil drop
often occupies the center of the mature oospore and this is
surrounded by a dense uniform layer of protoplasm. The
oogonial wall permanently invests the mature oospore (Plate
XX, 23, 24) as a loose envelope, but all signs of the antheridium
are often obliterated by this time.
Germination of oospores. The germination of the oospores
was tried several times, but they have failed to germinate up to
the first of April of the year following their development. The
germination of spores in pure cultures left out-doors during
the greater part of the winter will be tried later, since they too
failed to germinate as early as April.
Artificial cultures. This is the first time the downy mildew
of Lima beans has been reported as grown in artificial cultures,
and apparently the first report of the production of oospores
of any mildew in cultures of this character. The writer has
grown the downy mildew of the potato in artificial cultures
during the past two years and even previous to this two French
botanists had published accounts of its growth under similar
conditions. The downy mildew of tobacco is said to have been
grown in the same way. Apparently these three fungi, all
belonging to the genus Phytophthora, are the only species of
the Peronosporeae that have been grown in this manner.
The vigorous development of the Lima bean mildew in the
fall of 1905 suggested that perhaps it could be grown on various
media under control in the laboratory, as had been done with
the potato mildew. As certain precautions are necessary to
secure growths, a short account of the methods are given. In
the first place a culture cannot be obtained by transference of
spore material to a test tube from a growth on the pods. This
is because of sure contamination with other fungi or bacteria
which will stop or seriously interfere with the development of
the comparatively slow-growing mildew. Neither can cultures
be obtained from the spores by the Petrie dish separation
method, because of their slow growth and more natural germi-
nation by zoospores instead of by germ tubes. The best method
for securing pure cultures is to transfer into the culture tubes
pieces of the tissue, or better whole seeds, which contain myce-
lium of the fungus, taking these from the interior of pods show-
ing the freshest and least contaminated external growth of the
DOWNY MILDEW OF LIMA BEANS. 29/
mildew. Care should be taken in breaking or cutting open the
pods and a sterilized knife or forceps are necessary to remove
the tissue or seeds from the interior. The first attempts seemed
to indicate that cultures could be easily obtained in this way
but later experience showed that many of these became impure
with age. Other fungi, especial Fusarium, closely follow the
development of the mildew, and unless seeds or tissues in a very
early stage of infection are selected some mycelium of these
or bacteria will also be included and eventually spoil the cultures.
In the test tube cultures the following media were used:
(i) Living beans on moist cotton. These cultures were obtained
in two ways, (a) Beans were taken with aseptic precautions
from diseased pods and placed in the test tubes. As these beans
were usually already inoculated with the mycelium penetrating
into them from the pod, the subsquent development of the fun-
gus could be determined by examination from time to time,
(b) Beans were removed from perfectly healthy pods with the
same aseptic care and after placing in the test tubes were
inoculated with a culture of the fungus or tissue from a diseased
bean. The beans, especially the (a) cultures, usually formed
a more or less evident, though not luxuriant, external growth
of the conidial stage, but the greatest development was in the
production of oospores within the tissues. The beans generally
turned reddish brown, indicating enzymal action, and in some
cases there was practically no external growth of the conidial
stage. Plate XXI, a*, shows a bean artificially infected in which
oospores were produced abundantly but on which practically
no conidial growth occurred; at a** is shown a perfectly
healthy bean. Most of the successful cultures were made on
these living beans, as there was less interference from bacteria
and other fungi when the cultures were impure. (2) Steri-
lized bean tissues, of which the following combinations were
tried ; (a) whole beans on moist cotton, (b) a mixture of
ground green beans and pods, and (c) a combination of (b)
the corn meal. These were fairly good media, but bacteria,
yeasts and fungi bothered considerably if they were not
inoculated with perfectly pure material. Both the conidial and
the oogonial stages are formed. (3) Agar agar, usually made
with (a) potato juice water but in some cases (b) with sugar,
and peptone and certain salts. The mildew developed poorly
298 CONNECTICUT EXPERIMENT STATION REPORT, I9O5.
in most of these trials, but both conidia and oogonia occurred
to some extent. (4) Corn meal which was made up with
(a) potato juice, (b) peptone, sugar and certain salts, and
(c) ground beans and pods. Corn meal is a good medium
when once the fungus gets started, and in these trials also both
stages occurred. Because of oogonial production the fungus
did not penetrate as deeply into the medium as expected.
Cultures of the mildew were kept going from the middle of
September to the middle of November. At first there was a
more luxuriant growth of the conidial stage than toward the
end of the period and finally this stage seemed to so run out
that it was practically impossible to continue cultures. At
all times it was easier to start cultures from inoculated tissue
than from tufts of the fungus transferred by needle from one
tube to another. There was required, too, a certain degree of
moisture in the culture to insure the best growth. By far
the best results were obtained on the living bean cultures.
Fungi, bacteria and yeast bothered considerably, especially on
the sterilized media. It was very difficult to get cultures that
did not finally develop such impurities, though a number of
these were obtained. The growths of the Lima bean mildew
were in marked contrast with those obtained of the potato mil-
dew in that the development of the conidiophores was incon-
spicuous while the reverse is true in nature. No doubt the
formation of oospores greatly interferes with the conidial devel-
opment, and if this latter could have been secured alone, as it
was with the potato mildew, a much more luxuriant external
growth would have been made. One of the most interesting
questions connected with the cultures of these two mildews is
why in one case oospores were always produced and never in
the other. This question is discussed more fully in the follow-
ing article on the potato mildew.
PREVENTIVE MEASURES.
From the preceding discussion one can see that there are
certain conditions that favor the introduction and spread of the
mildew in the Lima bean fields. Some of these factors can
be controlled, at least to a certain extent, by the grower. In
the following paragraphs are given briefly the means by which
he may hope to prevent or lessen the injury inflicted by this
parasite.
DOWNY MILDEW OF LIMA BEANS. 299
Selection of seed. It has been shown how the dormant
mycelium and the oospores carr}' the fungus over from one'
year to another in the seed. If possible, therefore, the seed
should be gathered from a field entirely free from the disease.
Where this is impossible a very careful selection should be made
from pods that show no sign of the mildew and from these
onl}^ the best and least shriveled should be used.
Rotation. It will do no good to select disease-free seed if
this is planted on land that bore a diseased crop the year before,
as the old seed rotting in the soil will probably furnish oospores
for infection. Each year the beans should be planted on a
different piece of ground, so that three or four years pass before
it is again used for this crop. This is a practice not always
followed, as one large grower in the state, at least, has planted
beans year after year on the same land and his beans are sure
to be attacked by the mildew if any are that year.
Destruction of rubbish. Where rotation is faithfully fol-
lowed each year perhaps little good will be accomplished by
destroying the old vines, as the oospores probabh^ will not live
in the ground more than a year or two. Where, however, the
grower deems it very essential to use the same land the next
year for Lima beans, the chances for infection will probably be
lessened by gathering and burning in the fall all of the rubbish
of the old crop. It should be borne in mind in this work that
the pods and seeds are the parts it is most necessary to destroy.
Methods of planting, etc. The Lima beans are usually
planted to climb upright poles and these are set in rows to allow
cultivation in one direction. They should be set a sufficient dis-
tance apart in the rows (sa}' three to three and a half feet) and
the rows should be of sufficient width (about four and a half
feet) to allow free entrance of the "sunshine to dry off the foli-
age and prevent the enclosed air from being too damp. Neither
should more than two or three vines be grown to a pole for the
same reason. Low moist spots in the field favor the first infec-
tions and the spread of the mildew afterwards, so it is desirable
if such exist to plant some other crop on these spots. So, too,
considering injury from the mildew only, it is more advanta-
geous to use a high dry field than a lower more moist one.
Spraying. Sturgis is the only investigator who has reported
spraying experiments for the prevention of this mildew. His
300 CONNECTICUT EXPERIMENT STATION REPORT, I905.
first experiments were made in 1893 with a number of fungi-
cides, but as the mildew did not appear in this field even on
unsprayed vines no conclusions could be drawn, except that the
fungicides did not injury the foliage in any case. In 1897 he
made further trials using Bordeaux mixture, ammoniacal solu-
tion of copper carbonate, potassium sulphide, and sulphur as
the fungicides. The best results were obtained with a row
that was sprayed three times with Bordeaux and twice with
Amm. Sol. Cop. Car., as this yielded 296 marketable pods
against 25 on an adjacent unsprayed tow. Sturgis says, "The
conclusion to be drav/n from this experiment is that even in a
season most favorable to the Lima bean mildew, thorough treat-
ments of the vines with the Bordeaux mixture will ensure a
crop."
While the writer has conducted no spraying experiments for
the prevention of this mildew, he has watched certain fields in
the vicinity of New Haven that have been sprayed. From these
observations and the results of Sturgis' work the following sug-
gestions are offered: Spraying need not be commenced before
the middle of July, or possibly in very wet seasons about the
first of this month. Bordeaux mixture is the most satisfactory
fungicide and in later sprayings need not be replaced by
Ammo. Sol. of Cop. Car. or potassium sulphide if the market-
able pods are picked before each spraying. Even if some sedi-
ment does still adhere to the pods when picked, this can do
no possible injury unless prejudice militates against their sale.
The spray should be directed chiefly to the young parts of the
vines and should be delivered in a fine mist. It is most import-
ant that the spray reach the pods and least important that the
foliage be covered. Three or four thorough sprayings with
Bordeaux mixture will probably be sufficient for most seasons.
Most of the spraying observed by the writer has been partially
ineffectual because it was done too early in the season and
because the leaves were the parts chiefly protected.
Factors beyond control. Season is the chief factor in deter-
mining the amount of injury by the mildew. As stated before,
very wet weather from July to September is favorable for the
development of the trouble. Of course the weather can not
be controlled, but where one has taken the preceding precau-
tions his loss should be much less than one who has not. A
DOWNY MILDEW OF LIMA BEANS. 3OI
second factor not under control is insect visitation. As shown
by Sturgis, bees may spread the disease in a field and we have
reason to believe that they may carry it to a certain extent from
one field to another. This being- the case, one who makes the
preceding precautions to keep the disease out of his field should
also isolate it, as far as possible, from other fields, especially
from those that are likely to be seriously troubled. Where the
fields are very close together not only insects but also the wind
may help to carry the disease from one to another.
EXSICCATI.
Specimens of the Lima bean mildew have been issued in the
following exsiccati, all the specimens having been collected in
the vicinity of New Haven on Phaseolus lunatus: Seym. &
Earle Eco. Fungi, 9 (Thaxter, Sept. Oct., 1889) ; Ellis & Ev.
N. A. F., 2707 (Thaxter, Sept., 1890) ; Bri. & Car. Fung. Par.,
351 (Rorer, Sept., 1901) ; Ell. Ev. Barth. Fungi Col., 1949
(Clinton, Aug. 29, 1902).
LITERATURE.
The following references to the literature of this mildew
include all of any importance that the writer has been able to
find. Even some of these contain only data taken from Thaxter
and Sturgis.
1. Berlese, A. N. Phytophthora Phaseoli Thaxt. Riv. Pat. Veg., 9:
41-4. 1902.
Gives scientific description and general notes on this fungus,
which he lists only from New Haven, Conn., drawing his data
from Thaxter and Sturgis.
2. Briosi, G. and Cavara, F. Phytophthora Phaseoli Thaxt. Fung.
Par. No. 351. [Illustr.]
Issue specimens from New Haven collected by Rorer and give
figures and descriptions taken from Thaxter.
3. Clinton, G. P. Downy Mildew, Phytophthora Phaseoli Thaxt.
Ann. Rep. Conn. Agr. Exp. Stat., 1903: 307-8. 1904. [Illustr.]
Gives short general account of the fungus and suggestions for
its prevention.
4. Halsted, B. D. Notes upon Mildew of Lima Beans. Ann. Rep.
N. J. Agr. Exp. Stat, 1897: 297-9. 1898. [Illustr.]
Reports this very serious in Bergen Co., N. J., in 1897 ; mildew
worst on low land that had Lima beans on it the year before.
302 CONNECTICUT EXPERIMENT STATION REPORT, I905.
5. Halstead, B. D. The Phytophthora of Lima Beans. Bull. Torr. Bot.
Club, 25: 161-2. 1898. [Illustr.]
Notes this fungus as serious in New Jersey in 1897, which was
a wet season.
6. Halsted, B. D. Late Growth of Bean Mildew — Phytophthora
Phase oli Thaxt. Bull. Torr. Bot. Club, 26: 20. 1899.
Notes late growth of the fungus, Oct. 24, on the green pods
after the leaves had been killed by frost.
7. Halsted, B. D. The Downy Mildew of Lima Beans. Bull. N. J.
Agr. Exp. Stat., 151 : 18-24. 1901. [Illustr.]
Gives a general account of this fungus, which has proved a
serious trouble of Lima beans in New Jersey in wet seasons.
8. Halsted, B. D. The Mildew of Lima Beans. Ann. Rep. N. J. Agr.
Exp. Stat., 1902: 399-403. 1903. [Illustr.]
Reports troublesome in New Jersey in 1902 and gives extracts
concerning it from Bull. 151 of the New Jersey Station.
9. Jaczewski, A de. Phytophthora Phaseoli. Bull. Torr. Bot. Club,
29: 649. 1902.
Salmon quotes portions of a letter from above botanist, who
notes presence of this fungus in Russia.
10. Orton, W. A. Phytophthora Phaseoli Thaxt. Yearbook U. S. Dep.
Agr., 1903: 554. Ibid., 1904: 584.
Lists the fungus as injurious in Connecticut, New Jersey and
Delaware in 1903; but in 1904 it is reported only from New
Jersey.
11. Saccardo, P. A. Phytophthora Phaseoli Thaxt. Sacc. Syll. Fung.,
9: 341. 1891.
Gives scientific description taken from Thaxter and lists only
from New Haven, Conn.
12. Smith, C. O. Mildew of Lima Bean. Bull. Dela. Agr. Exp., 63:
23-4. 1904.
Deals briefly with this fungus and notes its appearance in
Delaware from July on in 1903.
13. Speschnew, N. N. Les parasites vegetaux de la Cakhetie. Arb. Bot.
Gart. Tiflis, lief. 2, 1897. [Review: Zeitsch. Pflanzenk., 11: 113.]
Lists Phytophthora Phaseoli Thaxt. from the Gouvr. Tiflis
(Kaukasus).
14. Sturgis, W. C. Mildew of Lima Beans. Ann. Rept. Conn. Agr.
Exp. Stat., 1893: 77. 1894.
Used several fungicides but as the fungus was not present in
the sprayed field their value was not determined.
15. Sturgis, W. C. The Mildew of Lima Beans (Phytophthora Phaseoli
Thaxt.). Ann. Rep. Conn. Agr. Exp. Stat., 1897: 159-66. 1898.
[Illustr.]
Gives a general account of the fungus and shows how bees
spread the fungus to the flowers ; gives results of successful
spraying experiments with Bordeaux mixture, etc.
DOWNY MILDEW OF LIMA BEANS. 3O3
16. Sturgis, W. C. On some aspects of Vegetable Pathology and the
Conditions which influence the Dissemination of Plant Diseases.
. Bot. Gaz., 25: 191-4. 1898. [Illustr.]
Shows how insects and wind are influential in the spread of
Phytophthora Phaseoli.
17. Sturgis, W. C. Mildew of Lima Beans. Ann. Rep. Conn. Agr.
Exp. Stat., 1898: 236-41. 1899.
Made experiments to determine efifect of thin and thick planting
an upright and slanting poles on amount of mildew, which was
very bad this season ; looked especially for means by which it
carried over winter in old rubbish but found nothing.
18. Thaxter, R. A new American Phytophthora. Bot. Gaz., 14:
273-4. 1889.
Gives a general and a scientific description of this new species,
Phytophthora Phaseoli Thaxt.
19. Thaxter, R. Mildew of Lima Beans -{Phytophthora Phaseoli
Thaxt.). Ann. Rep. Conn. Agr. Exp. Stat., 1889: 167-71. 1890.
[Illustr.]
Includes a general description of the fungus, an account of its
germination, its relation to other species and methods for its pre-
vention.
20. Thaxter, R. Mildew of Lima Beans. Ann. Rep. Conn. Agr. Exp.
Stat, 1890: 97-8. 1891.
Notes distribution of fungus in Connecticut, especially during
this year.
21. Thaxter, R. Phytophthora Phaseoli Thaxt. Journ. Myc, 7: 279.
1893.
Gives scientific description and references to literature of this
fungus.
304 CONNECTICUT EXPERIMENT STATION REPORT, I905.
DOWNY MILDEW, OR BLIGHT, Phytophthora infestans
(Mont.) DeBy., OF POTATOES. II.
In the Report of this Station for 1904 the writer gave the
first installment of his work with the potato blight. This
included a short general account of the life history of the
fungus, so far as known, and of spraying experiments looking
toward the most practical methods for controlling the disease.
The investigations of the past year, reported in this article,
have been made chiefly to determine more minutely and accu-
rately points in the life history of the fungus in the hope that
when this is definitely and completely known, prevention of its
ravages will be an easier task to those who take advantage of
this knowledge. The points that need especial elucidation are
the way or ways by which the fungus first infects the vines in
the summer (that is the primary infections), its history, if any,
in the soil, and the means by which it is carried over from year
to year. To gain such information the writer made careful
observations of the very first appearance of the disease in
various fields, examined the plants and tubers in all conditions
of health and decay, carried on indoor inoculation experiments
and grew the fungus in artificial culture for two years. We
are not yet satisfied with what is known of the fungus and hope
later to make additional reports concerning it.
Primary Infections.
Diseased plants. What conditions do the very first infec-
tions of the year in a given region or field require? We know
that the disease has never appeared, or at least has never been
recorded, in Connecticut before the first week of July, and
sometimes it is not found before the middle of August, and
that the more rainy, cloudy and foggy these months are the
quicker it gets a start and the more rapidly it spreads. Smith
and DeBary also report that the blight is seldom seen in
Europe before July or August, though rarely it has been found
oven in May or June. The common belief, or at least the one
advocated by DeBary concerning the advent of the fungus in a
field, is that it comes from "diseased plants."
Perhaps DeBary's (2) views can be best shown by the follow-
ing quotation: "The facts which have been observed estab-
DOWNY MILDEW OF POTATOES. 305
lish that there are two methods by which the conidia may
pass from the tuber to the foliage. First, it is known that
the mycelium of the fungus in the tuber, even when in the
ground, is able to produce conidiophores bearing conidia
directly from the tuber. We can easily see how the conidia
thus produced could reach the foliage — they might be carried
up either by the growing plant which may have touched them,
or by small animals which frequent both situations. Neither
of these methods can be easily detected. Moreover, the forma-
tion of conidia in the soil cannot be very frequent. There
should therefore perhaps be little weight attached to this
method. The second method can be easily observed and with
great exactness. It consists in the mycelium growing from the
tubers in and with the 3^oung plants and producing conidia on
them in the usual way; and these [diseased plants!] of course
extend the fungus to the healthy plants beside them. In 1861
I called attention to the fact that tubers containing Phytophthora
when they are growing, not unfrequently send out shoots into
which the fungus passes from the tubers. The fungus advanc-
ing slowly in its growth at last kills the shoots, which for the
most part were always in a sickly condition. The same tubers,
as is known, may also send out healthy shoots at the same time.
I further showed that under special circumstances the fungus
in these diseased shoots develops conidia. These were not
conjectures, but facts observed in experiments. The observa-
tions, however, were not made in the open field, but in the house
and laboratory, and had not been confirmed by myself or
observed by others in the open field." DeBary tried to demon-
strate this second theory by planting tubers he infected through
the eyes outdoors along with healthy ones, and obsersdng if,
upon the growth of the plants, the disease spread to the leaves
of all the plants. In his first trial, although he grew a diseased
plant, the fungus never fruited on this and so did not spread
the disease. In the second trial the healthy and diseased tubers
were planted out early in the garden in a box and several
diseased shoots appeared which in time developed a fruiting
condition of the fungus, so that before the end of May the
blight had spread to many of the leaves of all of the plants.
This was long before its appearance elsewhere in the neighbor-
hood.
20
306 CONNECTICUT EXPERIMENT STATION REPORT, IQOS-
The writer, thinking that DeBary's "diseased plants" might
offer the best explanation of the first appearance of the blight,
made special search for them in different fields after the vines
were above ground at various times up to the general appearance
of the disease, but was not successful in finding such plants.
True, one sometimes finds plants stunted by the bacterial stem
rot and also those with cankered areas on the parts below ground
caused by the Rhizoctonia fungus, but no sign of any disease
like or unlike these containing outbreaks of the blight fungus.
For two or three years efforts also have been made in the green-
house to produce blight diseased plants from tubers known to
contain the mycelium of the blight fungus. The badly diseased
tubers often failed entirely to grow ; others, less diseased, pro-
duced plants, sometimes making a poorer growth than usual,
but never showing any signs of the blight. Thinking that
possibly the greenhouse conditions were not favorable for deter-
mining this point, as the atmosphere there was usually rather
dry, a more extended experiment was conducted outdoors in
the spring of 1905. Through the kindness of some thirty
Connecticut potato growers who had suffered from rot of
tubers in 1904, a few potatoes showing disease were obtained
from each. While these growers were requested especially for
tubers showing the reddish superficial rot characteristic of
blight, the potatoes sent showed the Rhizoctonia, scab, and
Fusarium rot troubles as much or more than they did the blight.
The tubers were divided into five lots and planted in five rows,
as follows : ( i ) tubers freest from disease, also treated with
formalin; (2) same as (i) but not treated; (3) tubers badly
scabbed; (4) tubers with abundance of Rhizoctonia; (5)
tubers with Fusarium or blight rots, or both. In the last case
some of the tubers were badly rotted and the plants in this row
came up somewhat slower and less uniformly than in the others,
but there were no blight diseased plants seen at any time and the
first blight that appeared was on leaves of a plant in the row
whose tubers had been selected as freest from disease and then
treated with formalin ! Neither did the tubers produce any
more rot in the fifth row than those in the other rows, while
the row of scabby tubers produced a crop badly scabbed and
the Rhizoctonia row one with that trouble very prominent.
Other experimenters (Smith, DeBary) have also reported cases
DOWNY MILDEW OF POTATOES. 307
in which perfectly sound plants were grown from blight-
diseased tubers.
The only instance in which the writer has seen anything like
a blight-diseased plant, as recorded by DeBary, was in the green-
house, where a healthy tuber, planted in a crock with the top
just above the surface of the soil, was inoculated with the blight
fungus on one of the young buds, which was then covered with
moist cotton and a small bell jar. This bud was finally killed
and the reddish brown rot of the blight extended in time down
into the tissues of the tuber about a quarter of an inch and
spread for some distance beneath the skin, reaching another
eye from which eventually was grown a stem several inches
long. This stem, see Plate XXIV, b, about thirty or forty days
after the inoculation showed a reddish brown discoloration on
the exterior from the base to the tip and the conidial spores of
the blight fungus were produced sparingly upon it. The inte-
rior tissues of the stem, however, seemed to be perfectly healthy
and free from the fungus, and so if the disease came from the
mycelium in the tuber growing up into the stem, this growth
occurred in the external tissues rather than through the bundles,
as one might expect. There was a possibility, even in this case,
that the disease was inoculated externally by lice carrying
spores from the inoculated place on the tuber, since perfectly
healthy stems grew out of the sides of this diseased one. So
far as the writer can judge from reports in literature and his
own experience, DeBary's "diseased plant" method of primary
infection does not seem to have sufficient support so far to jus-
tify the belief that it is the common method in nature.
Contact of leaves with ground. But if the blight does not
generally first spread from a diseased plant, how does it start in
a field? There is offered here an explanation which our obser-
vations of the past year seem to indicate as the ordinary method
of infection. Possibly this idea has been advanced before,
since the writer has not carefully examined the literature to
determine this point. In support of our observations that the
blight does not usually start from diseased plants, let us first
quote the following from Smith (6, p. 293) : "It is obvious
that if the potato disease is annually reproduced by diseased
tubers containing perennial mycelium, the disease must invaria-
bly begin in the seed tuber and ascend the stem ; but it is known
308 CONNECTICUT EXPERIMENT STATION REPORT, I905.
b}^ experience that in the vast majority of instances this is not
the case, but that the disease first invades the leaves." This
corresponds with our observations of the past summer ; namely,
that the disease first appeared on a few leaflets, often on the
outermost leaves, of the fully grown, perfectly healthy plants,
and these conditions of its appearance preclude the belief that
the disease came by the mycelium in the diseased tubers ascend-
ing the stems and growing out into the leaves, all without caus-
ing any injury or evidence of its presence until finally it
produced the characteristic black spots on the isolated leaflets!
But Smith does not state definitely how the disease came on
the leaflets in these cases. We believe it comes by contact of
the leaves with the ground at the critical ivet periods of July and
August zvhen the germs of the blight are probably first generally
available in the soil for infection, and that this is the ustial
method of primary infections in the fields.
In support of the preceding statement we give the following
evidence: The season of 1905 was dry during midsummer, so
the blight was backward in its appearance. A number of fields,
chiefly in the vicinity of New Haven, were examined from time
to time tO' note the very first signs of blight. Weather favorable
for this trouble came on about August 9th to the i6th and the
first blighted leaves found anywhere, August nth, were in an
isolated field at Southington that had not been examined before.
This field of two or three acres had been in potatoes the year
before but was greener and in a better condition than many
fields at this time, as the drought and other agents had been
very injurious. After a careful search of the field the attempt
to find any blighted leaves was about to be given up when two
plants near together were found on which a dozen leaflets
showed a single blight spot each. Two of these leaflets were
still in contact with the moist ground and half of the others
showed by the dirt on them that they had recently been in con-
tact with the soil. Of course it is possible that some of these
spots may have come from secondary infections, as the fungus
was already fruiting on these leaves. There was no sign of a
diseased plant in the field so far as observed and certainly none
in the vicinity of the outbreak, and an examination of the two
plants having the diseased leaflets showed no sign of the fungus
on their stems. The later development of the blight in this
DOWNY MILDEW OF POTATOES. 3O9
field was not observed. The second place where the blight
was found was on August 12th, in the small isolated plat at the
Experiment Station, previously mentioned, where the tubers
showing different kinds of disease were planted. In this case
they were in sod land that had not been in potatoes before. The
plat was carefully watched, so that a diseased plant could not
have escaped observation. Here, too, no such plant occurred
and the blight first appeared on a healthy plant which had
about ten leaflets with single blight spots, in fruiting condition,
when found. Two of these leaflets were still in contact with
the soil and two thirds of them showed dirt on their under
surface, indicating recent contact with it. There were no out-
breaks anywhere on the stem of this plant or even on the parts
below the ground so far as could be observed. The disease
afterward gradually appeared throughout the plat. The third
case found was in an isolated field of half an acre in Whitney-
ville, by which the writer often passed and stopped to look for
the blight. This was first found August i6th, when after a
careful search a plant was discovered with a single leaf showing
the blight. While this leaf was then off from the ground, the
dirt on its under side again showed recent contact with it. A
photograph of this leaf is shown in Plate XXIII, a; only the
badly diseased leaflet was producing conidial spores. No sign
of the blight was found on any other part of the plant, though
looked for carefully. In a second place in the field, but removed
from this, another plant was found with several blight spots on
the leaves, some of which were still in contact with the ground.
Here the blight had spread, in some cases, from the blades onto
the pedicles and petioles, but these were always near the blight
spots and all of the petioles were perfectly free from the disease
at their base. There was again absolutely no sign of the fun-
gus on the stem of the plant. Later the blight gradually spread
over the field. Other fields examined up to this time had shown
no blight, but by the 22d of August it was found appearing
generally in a number, so that from this time on the disease
was not uncommon in fields still green.
Planting potatoes zvithout rotation. It is not an uncommon
practice for farmers in this state to grow potatoes two consec-
utive years on the same land and there is at least one field in the
vicinity of New Haven that has had potatoes on it for several
3IO CONNECTICUT EXPERIMENT STATION REPORT, I905.
years in succession. While the writer has not yet determined
from his own observations whether the fungus can carry over
the winter in the old tubers in the soil, Massee (3) of England
makes the following very definite statement: "I have observed
the important fact that, when the diseased potatoes are planted,
after the crop has been lifted, the remains of the old seed pota-
toes when brought to the surface of the ground will produce
a crop of the fungus bearing myriads of spores. If such old
seed potatoes are kept buried in soil until the following year
and then exposed to light, under favorable conditions, fungus
fruit is still produced, and continues to grow so long as a scrap
of the old potato remains. I have now in the laboratory at
Kew Gardens scraps -of last year's seed potatoes covered with
the fungus, and with the spores thus produced have success-
fully inoculated the leaves of young potato plants." If Massee's
statement is true, then fields used two years in succession should,
as a rule, develop the blight earlier and spread it more rapidly
than fields not in potatoes before for some time. As the writer
knew of three fields which had produced a badly diseased crop
the year before and were used again last year for potatoes,
these were examined to see if this was so. The one most care-
fully watched was in Westville and had abundant rotten tubers
from the preceding crop left on it. In this case, however,
the vines were practically dead before any blight appeared in
the neighborhood, so that all that could be determined was that
its use a second year did not cause an unusually early appear-
ance of blight in it. The other two fields were at Green's
Farms and so could not be watched so closely. When first
examined on August 19th they both showed blight more promi-
nently than other fields in the neighborhood. This was espe-
cially true of the earlier plant field, in which the blight was
very prominent, while another field on the same farm isolated
from this, but on land not in potatoes for years, was at this
time practically free from blight — only a single blighted leaf
being found there. On August 28th at Hamden a fourth field
was examined that was said to have had potatoes on it several
years in succession, and this showed more blight in it than had
been seen in any field up to that time in the vicinity of New
Haven. Other fields examined generally showed an earlier
or a more vigorous start of the blight if they had been in pota-
DOWNY MILDEW OF POTATOES. 3 I I
toes the year before. We do not wish to state positively, from
these observations, that the blight starts earlier and more vigor-
ously in a field that bore a blight-diseased crop the year before,
as such factors as situation of the land, earhness of planting,
etc., may need consideration here, but so far as they go they
seem to point to this conclusion.
Secondary Infections.
By secondary infections are meant all those that take place
from and after the original infections (the outbreaks on a
diseased plant, if such exists, or on leaves infected from con-
tact with the ground), and thus generally spread the disease
to the leaves of these plants, to those throughout the field or
even to other fields. The means cited here (rain, wind, and
insects) have usually been considered agents for the distribution
of the blight spores, though few special observations have been
published showing them to be such or indicating how far the
disease may be carried by them. To determine these points
more fully the following observations and experiments were
made the past year.
Rain. The testimony of all who have written concerning
blight shows that rainy or moist, muggy weather is absolutely
essential to the development and spread of blight in the fields.
This is especially necessary for this fungus because the spores
on germination usually form swimming spores, zoospores,
which are the common agents of infection. Not only is moist
weather necessary for infection, but dry bright weather follow-
ing the infection largely stops the spread and even the devel-
opment of the fungus already within the leaves. The moist
blackened tissues then dry up, and though the disease may seem
to have suddenly caused great damage, it is not progressing
into the healthy green tissues beyond as it would have done had
the weather remained moist. Rain not only induces the for-
mation and germination of the spores, but it serves as an agent
in distributing them. over the infected plants and also washes
them down into the soil to the tubers. It can not of course be
of much service in carrying spores from one plant to another
unless they overlap, and therefore by itself could only very
slowly spread the disease throughout a field if there had been
but a single starting point.
312 CONNECTICUT EXPERIMENT STATION REPORT, I905.
Wind. It is not so easy to prove that wind serves as a means
of distribution, but it no doubt acts as a carrying agent of the
spores to vines in the same field or to fields situated closely
together. The fungus, however, is not especially adapted for
dispersal by the wind, since the spores are borne on the under
side of the leaves and on the whole are not produced in great
abundance. The dry winds of bright weather would be of
little value, as it is in such weather that the spores rapidly lose
their power of germination and would find least opportunity
for germination, even if carried into a field. It does not seem
likely, therefore, that' wind is a common agent in carrying the
spores from one isolated field to another. The case cited in a
previous paragraph — the field the second year in potatoes at
Green's Farms in which blight developed vigorously and early —
seems to indicate that wind may be a prominent agent of dis-
persal for short distances, since the prevailing winds were from
the direction of the infected field toward an adjoining one,
which also soon became infected with the blight.
Insects. Apparently insects are a common agent in the dis-
tribution of the spores throughout a field, and the chief means
of conveying them from one field to another somewhat remote.
In other words, if it were not for insects, the selection of an
isolated field which had not been used recently for growing
potatoes and which was planted with tubers free from the
disease should give a crop exempt from blight. The most
common insects in the potato fields of Connecticut are the flea
beetle and the common potato bug, or Colorado beetle. The
latter is well adapted for carrying spores, since the under side
of the tarsi of the legs, especially the third tarsus, is provided
with a stiff brush of hairs that would easily retain spores tem-
porarily as the insect crawled over an infected leaf. The only
insect examined to determine this point did not actually have
the spores of the blight fungus on the brushes of hairs, but
these did have spores of other fungi, showing they could serve
such a purpose. The soft, somewhat moist body of the larvae
of the potato beetle, too, possibly aids in distributing the spores.
Just how helpful to the fungus the flea beetles are in this work
is not known.
To determine whether insects could carry the blight from
one isolated field to another, an experiment was conducted last
DOWNY MILDEW OF POTATOES. 313
year at Mr. Burr's place near Green's Farms. The potatoes
were planted in a garden on soil that had not contained potatoes
for at least five years. The garden was isolated and well sur-
rounded by trees, etc., and was not situated so that wind would
blow from another field toward it. The nearest potatoes were
at least an eighth of a mile awa}^ and the badly diseased field
mentioned before, about half a mile. The seed tubers were
obtained from Colorado on the recommendation of Mr. Orton
of the Division of Vegetable Pathology of Washington that
this was a region of the United States exempt from blight. So
far as could be learned, the grower of these potatoes had never
been troubled with this disease and Professor Paddock of the
Colorado Experiment Station writes that he has never identified
the blight in that state. These potatoes were examined the
same time, August 19th, that the writer looked through the
other fields on Mr. Burr's farm. After a searching examina-
tion a couple of leaves showing the blight were found, and Mr.
Burr wrote in the fall that eventually these potatoes suffered
from the blight about as badly as the others. Without much
question the potato bug was the means of introducing spores
for the first infection, after which the blight spread from this
throughout the plot. Part of the Colorado potatoes were
planted on land not recently in potatoes, but very close to the
badly blighted field mentioned before, and these on August 19th
showed considerable blight on the leaves. Both the wind and
insects were no doubt the carrying agents here. Some potato
seed was also obtained from this Colorado grower and planted
in the greenhouse during the winter and the young seedlings
set out later on the Experiment Station grounds about five
rods from ordinary garden potatoes. These seedlings, too,
became infected with the blight, but not until sometime after
it appeared on the garden potatoes. The potato bug was again
the most probable carrying agent. From this experience, the
writer concludes that the grower can not depend upon isolation
of a field and absolute freedom of soil and tubers from the
fungus to secure a crop free front blight since insects are very
likely to carry in the disease, though the more isolated the field
the less likelihood of infection. Such conditions, however,
will insure a later appearance of the blight in the field, but
whether retarding the invasion will prove of any practical value
314 CONNECTICUT EXPERIMENT STATION REPORT, I905.
will depend upon how long the infection is delayed and the
weather conditions thereafter.
Artificial Infections.
By this is meant indoor infections produced by the writer,
chiefly with pure artificial cultures of the blight fungus. To
secure infection it is necessary that the cultures be in fresh
spore-producing condition and that the inoculated plants be
kept moist or in a moist atmosphere, not only during the infec-
tion period, but also afterwards if the fungus is expected to
appear in its fruiting stage on the surface of the infected parts.
The few experiments tried were made to determine how easily
infection takes place under different conditions and how soon
the conidial stage appears after the spores are applied. Both
leaves and tubers were used as subjects for infection.
With the leaves. DeBary showed that the germ tubes of the
zoospores of potato blight can enter the leaves either through
the stomates or by penetrating directly through the epidermis.
The usual method in the latter case is for the germ tube to
push its way down between the walls where^ two cells come
together and then grow down into the intercellular spaces of
the leaf beneath, but DeBary also observed cases in which the
germ tubes bored directly into the epidermal cells themselves.
The ability of the fungus to gain entrance in these various ways
greatly aids its spread over its hosts. The stomates are more
numerous on the under surface of the leaf, but most of the
infections probably take place from the upper surface, as the
spores are most likely to be carried here from the conidio-
phores borne on the under surface of leaves above.
In our infection experiments after the spores were placed on
the upper surface of the young leaves, usually by the end of
three days it could be determined if the inoculation was suc-
cessful by the slight discoloration of the tissues. By the end
of the fourth day this discoloration was more evident and
conidiophores were beginning to protude through the stomates,
and by the end of the fifth day the diseased spot was well
marked and a few mature conidiophores and conidial spores
were present. As these spores can germinate immediately, sec-
ondary infections could take place within five days after the
primary. Perhaps the development of the fungus can be shown
DOWNY MILDEW OF POTATOES. 315
best by a detailed account of the infection of the plant shown
in Plate XXIV, a, which was photographed ten days after the
spores were applied. Its history is as follows : January nth,
placed spores in water on three lower leaves, covered each with
a small piece of moist cotton and the plant with a small bell jar.
January 14th (3 days), the two lower leaves showed slight dis-
coloration at points where spores were placed. January i6th
(5 days), the spots were well marked and conidiophores and
spores were formed in small numbers, January i8th (7 days),
about two thirds of the two lower leaves were plainly diseased
(yellowish, limp and partly blackened) and the conidiophores
were developing over the greater part of this area, but most
abundantly on lower surface ; two diseased streaks showed on the
stem but had few conidiophores on them ; petiole of one leaf
was covered with conidiophores, but showed little discoloration.
January 21st (10 days, see illustration), the two lower leaves
were dead and hanging limp ; the third leaf showed yellowish
discoloration over apical half and was producing conidiophores ;
the fourth leaf (apparently a secondary inoculation by lice)
had a few conidiophores on it, but no injury to its tissues showed
as yet; several blackish streaks showed on the stem where the
fungus had gained a foothold from the diseased leaves above.
With the tubers. There are a number of different conditions
under which inoculation of the living tissues of the tubers may
be tried ; namely, on the cut surface in a moist atmosphere, on
various uninjured parts (eyes, buds, skin) before or after
removal of the tuber from the plant, or on these same places
after mechanical injury to them. In the experience of the
writer the development of the fungus varies greatly under these
dissimilar conditions. It grows most luxuriantly, at least exter-
nally, on the cut surface of the tuber in a moist atmosphere.
Before inoculation it is always desirable to soak the whole tuber
in a 2 per cent, formalin bath for half an hour and to use a ster-
ilized knife in cutting it, in order to limit as much as possible the
development of other fungi and bacteria which easily crowd out
the Phytophthora. Discoloration of the tissues, at least for
some time, does not follow the development of the fungus on
the cut surface of the tuber ; this probably indicates very super-
ficial penetration into the tissues.
3l6 CONNECTICUT EXPERIMENT STATION REPORT, I905.
DeBary states that he secured infection of the tubers very
readily through the terminal eyes. Presumably the buds were
slightly developed in the tubers he used. Our experiments,
at least, seemed to indicate that it is very much easier to secure
successful inoculation through the very young buds than it is
at the eyes of a perfectly dormant tuber in which no bud is yet
evident. These experiments, too, go to show that inoculations
on the uninjured skin of a dormant tuber are not likely to be
successful, while at the same spot if the skin is first injured
by a knife puncture the inoculation succeeds. Likewise, in the
single experiment tried, the inoculations were not very success-
ful on the uninjured skin of very young tubers still attached to
the plant, and scarcely more so when the tissues were injured
before inoculation. Possibly some of these results were partly
due to the age of the cultures used, but even then there seems
to be no doubt that there is greater variability and difficulty in
securing infection of the tubers than of the leaves.
Three of these inoculation experiments with the tubers are
recorded here: i, November ipth, tried to inoculate five dor-
mant tubers, using artificial cultures of the blight. Each tuber
was buried in the soil of a crock so that a single lateral, deeply
indented eye, showing no sign of bud formation, was exposed
above the surface of the soil. These uninjured eyes served
as a cavity into which the spores and water were placed, when
they were then covered with watch crystals lined with moist
paper to retain the moisture. The tubers, however, were so
thoroughly seasoned that the water in the eyes was rapidly
absorbed and had to be replaced many times during the next
few days, though the soil around the tubers was also kept moist.
Possibly this dying out influenced the result, for not a single
inoculation was effective, and at the end of 32 days the tubers
were still perfectly sound at these eyes. 2, December 21st,
used the same tubers but placed the spores away from the eyes
on a small spot where the skin had been injured by a knife.
On examination ten days later rots showed at all of the points
of puncture. Some of these were the characteristic dry reddish
brown rot of the Phytophthora, with or without the conidio-
phores showing slightly at the punctured point, while in other
cases bacteria were also agents of the decay. January 9th one
of the tubers was half rotted and a short shoot from it had been
DOWNY MILDEW OF POTATOES. 31/
killed by Phytophthora and bacteria, having, apparently, become
inoculated externally by lice. February 21st, took up all of the
tubers and the plants that had developed from them. All of
the seed tubers were entirely rotted, showing more or less of
the characteristic reddish brown dry rot of the Phytophthora,
especially near the outside, but all but one had produced plants
and small tubers. None of these new tubers showed any sign
of rot; neither were any of the plants diseased. Cross sec-
tions of the stems close to the old seed tubers and of the under-
ground shoots running from these to the new tubers in no case
showed any sign that the mycelium of the blight fungus had
passed or was passing from the diseased tubers into these, j,
February 21st, inoculated four young tubers (about one inch
in diameter, growing in greenhouse bench) with culture of the
blight fungus, — two with and two without injury to tissues.
February 23d the injured spots showed evident but very slight
rot, while the uninjured showed doubtful start. March 20th
the injured spots had rotted but little, being only ^ of an inch
in diameter and extending but slightly into the flesh ; while
the uninjured spots were only about ^ of an inch in diameter
and still more superficial. The fungus did not fruit at any of
these places and bacteria may have been partially responsible
for the rot, though in the case of the check tuber, injured but
not inoculated, no rot appeared.
Artificial Cultures.
So far as known to the writer, the reports of Matruchot and
MolHard (4, 5) made in 1900 and 1903 are the only ones so far
published concerning pure artificial cultures of the blight fun-
gus. The work reported here was begun in the fall of 1904,
before learning of the investigations of these French botanists,
and has been carried on now for about two years. Growth of
the fungus on various media in test-tubes was undertaken
chiefly to see if this would not throw some new light on the
life history of the fungus, especially with regard to the missing
oospores. The general results obtained agree with those of
the French investigators, though the details of methods and
media used were not altogether the same.
Hozv obtained. Pure cultures of the blight fungus are not
so easily obtained as are those of many fungi, since because of
3l8 CONNECTICUT EXPERIMENT STATION REPORT, I905.
their slow growth they are easily crowded out in competition
with other fungi, and because the ordinary Petrie dish separation
method is not available with their spores, which prefer a fluid
medium for germination. Matruchot and Molliard apparently
made most of their cultures by exposing the cut surface of an
infected tuber in a moist chamber until the fungus ran out on
this in its fruiting stage, when material from the growth was
transferred by a sterilized needle to test tubes containing various
media. Such growths on the tubers are nearly always contami-
nated_and usually only a few of the cultures made from them
remain pure. If the tubers are first sterilized on the outside
by a bath in formalin and cut with a sterilized knife, better
results will be obtained. It is desirable, too, if possible, to use
only tubers showing a superficial decay of the Phytophthora
rot. On the whole, the writer was most successful in obtaining
cultures when the reddish brown diseased tissue from the inte-
rior of a tuber next the healthy tissue was removed in small
pieces, about a third of an inch in diameter, by a sterilized knife
and then inserted on the medium in the test tube. In this case
the mycelium from the diseased tissue in time runs out onto
the medium and often produces a pure growth of the fungus.
Where infected tubers are not available for cultural work, the
fungus can be started on the freshly cut surface of a sterilized
tuber by suspending over it a leaflet containing a vigorous,
fresh outbreak of the blight. The spores falling on the cut
surface soon start a growth of the fungus, from which material
may be transferred to the test tubes. Here, too, contamina-
tions usually prevail in spite of precautions. Plate XXIII, b,
shows a nearly pure growth of the fungus started in this way.
One of the most common fungous interlopers is a species of
Fusarium and it is often impossible to distinguish between the
growths of this and the Phytophthora and they soon become
intermingled. Microscopical examination is usually necessary to
determine which part of the growth on the cut surface of the
potato presents the blight fungus in a pure condition.
Media, Appearance, etc. Altogether twenty-five to thirty
different cultural media and modifications of the same medium
were tried to determine the most satisfactory ones and also
to see if the fungus could be induced, under different conditions,
to develop any unknown stage. These media fall in four gen-
DOWNY MILDEW OF POTATOES. 3I9
eral classes; viz., i. Plugs of living plant tissue, 2. Sterilized
plant products, 3. Agar agar media, 4. Earth and manure.
The results are discussed briefly in the following paragraphs.
1. The writer found, as did Matruchot and Molliard, that
plugs of living tissue taken with antiseptic precautions from
the interior of a potato, and to a less extent from the pumpkin,
offered a very favorable medium for the growth of the fungus.
These plugs were cut from the interior of a sterilized tuber with
a knife, which had been sterilized with heat and allowed to cool
so as not to sear the tissue, and after slicing off the sides a sec-
ond time were placed in the test tubes on a sterilized cushion
of cotton saturated with water. With proper care these plugs
can usually be obtained free from organisms and if the atmos-
phere of the tube is kept sufficiently moist upon inoculation the
mildew forms a very favorable growth. This is more or less
luxuriant, apparently, according to the conditions of moisture
and the success with which the original infection took place.
Sometimes a scanty growth of normal conidiophores producing
numerous spores occurs or again a conspicuous pure white felt
develops, of which a large part is made up of mycelial threads.
Plate XXV, a, shows (b) a rather scanty and (c) a very luxuri-
ant growth of the fungus, (a) being a check or uninoculated
tube. On the other hand, similar plugs taken from the sweet
potato, apple, and cucumber gave practically no growths.
2. Sterilized corn meal properly mixed with water was the
best medium used. The chief difficulty lies in inoculating
these tubes, as the top of the corn meal usually dries out in a
short time into a hard mass and this may prevent the fungus
getting a proper start. On the other hand, the mechanical con-
ditions allow the fungus, when once started, to gradually work
down toward the more moist base of the tube. To facilitate
inoculations and removal of tufts of the fungus, it is best to
have the corn meal in a slant at its upper end. Plate XXV, b,
shows a growth of the mildew on corn meal, of the same age as
those shown on the potato plugs. In the few trials made, a mix-
ture of ground green Lima bean pods and seeds with corn meal
gave very satisfactory growths and probably this medium with-
out the corn meal would do as well. Sterilized potato plugs,
however, gave scarcely any growth, and according to Matruchot
320 CONNECTICUT EXPERIMENT STATION REPORT, I905.
and Molliard this is due to the mechanical interference of the
swollen starch grains in preventing the spread of the fungus.
3. Agar agar cultures, with various ingredients added, were
tried, but on the whole were less satisfactory than the preced-
ing media. Most of these cultures gave slight growths, while,
in all, the fungus was slow in developing. Usually a slight
growth of the mycelium penetrated the medium and a more or
less conspicuous development of conidiophores and mycelium
was formed on the surface. Potato and pumpkin juice agar
media were as satisfactory as any tried. Plate XXV, c, shows
an old culture on pumpkin juice agaf, in which the development
was more prominent than usually obtained on agar media.
4. Sterilized manure, earth, mixtures of these and of these
with other ingredients were used to a limited extent to see if
they would furnish proper media for the development of the
fungus. It was thought that if this was the case there might
be some ground for believing that the fungus made some such
development in nature. In all of these trials the growths made
were very slight or there was none at all. The very poor
growths noticed were due, in some cases, to the medium added
with the fungus on inoculation. So far as could be learned
from these cultures there is no reason for believing that the
fungus makes any unknown growth in the soil.
Results. These investigations showed that the fungus can be
grown in artificial cultures rather readily under favorable con-
ditions. The cultures can be kept alive for some time, especially
on a medium, as corn meal, allowing the fungus to spread
slowly through it. By occasional re-inoculations the fungus,
apparently, can be kept indefinitely in culture. In some cultures
and under some conditions, there is a more luxuriant develop-
ment of the fungus than in others. The most conspicuous
growths usually indicate a more vigorous mycelial than conidial
development. No sign of an oogonial or other unknown stage
appeared in any of the cultures. In one case, however, there
was a very slight growth from the pieces of an infected tuber
inserted in agar tubes and in this medium some peculiar swollen'
bodies were formed whose nature was not definitely determined.
They resembled somewhat the immature so-called oospores that
Smorawski (7) has figured. A few cross inoculations were
tried with cultures obtained from different sources, but nothing
DOWNY MILDEW OF POTATOES. 321
unusual occurred. These trials were made with the hope that
different mycelial strains might be discovered whose growth
together would result in the production of oospores. As the
different cultures were few in number and were obtained chiefly
from the same vicinity, but during two different years, it is not
desirable to draw even a negative conclusion from the results.
Perpetuation of the Fungus.
The known vegetative and reproductive states of downy mil-
dews in general are mycelium, conidial spores, zoospores and
oospores. The conidial spores and zoospores are so short lived
that these fungi, so far as known, have to depend on the myce-
lium and oospores to carry them over the unfavorable
winter period. In the following paragraphs is discussed how
the potato blight is, or possibly may be, perpetuated.
Dormant mycelium in tubers. So far, this is the only way
in which it is positively known that the fungus survives the
winter. The disease caused by its presence in the tuber does
not need to be conspicuous, and in fact the more diseased the
tuber the less capable this is of germinating and so, presumably,
the less likely it will be of perpetuating the mildew. The fungus
may be present in the tuber and yet escape notice, as the rot is
sometimes very superficial and slight ; in fact DeBary records
a case where the fungus grew out on the cut surface of a tuber
he was using for an experiment on the supposition that it was
entirely free from the fungus. This being true, it is doubtful
if much good would result where tubers were selected to avoid
diseased ones, though it is not advisable, of course, to use those
showing a superficial or even deep-seated reddish brown dry
rot. The mycelium in the tubers seems to be much less active
in the spring than when the tubers are first dug. Ordinarily
in the fall if the cut surface of a diseased tuber is exposed in a
damp chamber the fungus will spread more or less over this
surface. On the other hand, of the thirty samples obtained
from Connecticut growers and tested in this way in the spring,
the fungus developed on only two lots, yet most of those tried
had the appearance of blight tubers. This decreased activity or
vigor of the fungus is apparently due to the drying out of the
tissues of the tuber, which induces a hibernating condition of
21
322 CONNECTICUT EXPERIMENT STATION REPORT, I905.
the mycelium, and in some instances where the tubers have been
stored in unusually dry places no doubt the mycelium does not
survive.
Two views are advanced to explain how the mycelium in the
infected tubers planted in the spring perpetuates the fungus.
First; by growing up from the tuber into the stem, it produces
a "diseased plant." This view has been previously discussed
in the paper. We believe that the mycelium rarely passes up
into the plants in this way, and just as rarely passes down from
the plants after infection into the new tubers, as was formerly
believed by some investigators. Second, the mycelium forms
the conidial stage on the cut surface of the tubers or rarely in
tufts through punctures in the skin, and the conidial spores or
their zoospores, on being carried to the buds of the tuber or
later to older parts, cause infection. The chief objection to this
view is that infection in this way probably could only take place
during a short time in the spring (the writer's and DeBary's
experience indicates that the mycelium forms the conidial spores
only on the living and not on the badly diseased tissue of the
tubers) whereas the first visible outbreaks, so far as known,
do not appear until July or August. Could it be possible that
owing to the rapid growth of the young plants these primary
infections remain isolated in the tissues and do not develop
further until the growth of the host ceases and faf orable blight
weather appears ?
Hetercecism. This means that a fungus has different stages
of its development on different hosts, as is the case of the wheat
rust with two stages on barberry plants and later two more on
wheat. DeBary, who first demonstrated this life cycle of the
wheat rust, has discussed the possibility of the potato mildew
being heteroecious. He concluded that there was no likelihood
of this being so, though at one time false rumors stated he had
found a different stage on another host. There are absolutely
no data in favor of such a supposition for the potato mildew
and no evidence of heteroecism has ever been found for any
of the downy mildews.
Unknozvn stages. Various writers, often to support some
theory, have suggested possible or probabl^e stages of the potato
mildew, not known for other downy mildews, but no real evi-
dence of their existence has yet been produced. For instance,
DOWNY MILDEW OF POTATOES. 323
Smith (6, p. 292) writes : "It is not unreasonable to imagine
that some other condition of the parasite, at present quite
unknown to and unsuspected by us, might be brought to Hght.
The fungus may exist in inconceivably fine dust-like particles
or in the condition of a mucous fluid." This was an entirely
theoretical suggestion, but a Scotchman, A. S. Wilson (8),
advocated a more definite unknown stage. His theory was as
follows : 'Certain bodies were found on the under side of
leaves, in all parts of the stem, especially at the nodes, and in
the tubers, especially around the eyes. These he originally
called sclerotiets (analogous to sclerotia) but later named
them granules of mucoplasm. They are translucent, micro-
scopic globular bodies coated with oxalate of lime. His obser-
vations caused him to believe that these, on germination, gave
rise to the mycelium of the potato mildew and that thus the
disease could break out on any part of the host without trans-
location. As the resting spores are not parasitic but live and
germinate in the soil or in any dead matter, it is contact with
the mucoplasm exuded from their fresh mycelium which
originates the parasitism in the potato. As the tubers are
infected, especially at the eyes, with mucoplasm granules, the
general elements of the parasite are carried over from one race
of potatoes to the following and from one season and country
to another, not requiring invasion from without for a new dis-
play of the disease.' This is apparently a case where there is
too much theory and too little exact observation and no experi-
mentation to back it.
Oospores. These are thick- walled sexual spores often pro-
duced by the downy mildews and constitute the common means
by which they are carried over from one season to another.
Several investigators claim to have found these spores for the
downy mildew of potato, but in no case have they produced
sufficient evidence to satisfy botanists in general of their reality.
Different suggestions have been advanced to account for the
absence or rarity of these spores, and these, briefly summarized,
are as follows: i. That the oospores have never existed for the
potato mildew. 2. That this mildew has lost the power to pro-
duce these bodies. 3. That they may occur only in certain
regions of the world. 4. That they are produced only in cer-
tain hosts, — the potato mildew having been found on a number
324 CONNECTICUT EXPERIMENT STATION REPORT, I905.
of Other plants. 5. That they are formed in the potato more
as a saprophyte than as a parasite. 6. That possibly these
spores are formed only on the union of distinct mycelial strains
which do not commonly occur together — a suggestion by the
author.
The more the writer looks into this matter the more he is
inclined to believe that oospores of the potato mildew do exist,
especially since he has recently demonstrated their presence for
the closely related species occurring on the Lima bean. There-
fore, so far as he is concerned, the first two suggestions given
above may be dismissed as unsatisfactory. Those persons who
suggest special regions where the oospores may be found name
Chili, the original home of the potato, as a possible locality or
region where the genus Solanum occurs in a wild state. This
mildew has been recorded on a number of the Solanaceae, more
especially on the genus Solanum, and even on a couple of the
Scrophulariaceae family. The writer has not had opportunity
to study the blight to any extent outside of Connecticut, and,
besides the potato, has collected it only on the tomato. Spec-
imens of the latter, collected both in Connecticut and Porto
Rico, did not throw any light on the oospores. The question
of hosts and distribution cannot, therefore, be discussed on the
basis of personal experience. The fifth and sixth suggestions,
however, have had our attention during the past two years and
may be discussed further.
Are oospores produced in decaying potato tissues? Worth-
ington Smith, of England, was the most prominent advocate
of the existence of oospores and claimed to have found them
commonly in that country in the decaying leaves and tubers.
The Royal Horticultural Society awarded him a gold medal
for his alleged discovery. While his investigations were made
twenty to thirty years ago, they have never been substantiated
unquestionably. At the same time he was at work, DeBary,
of Germany, the most able mycologist of his time, was also
undertaking a study of the potato disease at the request of the
Royal Agricultural Society of England. He was unable to find
any positive evidence of oospores and he criticized Smith's work
severely and apparently on good grounds. There is no doubt
that Smith did not always record accurate observations, and
there is little doubt that in his study of the developing "oospores"
DOWNY MILDEW OF POTATOES. 32$
he dealt with more than one fungus. The chief question is,
however, did he have under consideration at any time true
oospores of this fungus. Unfortunately the writer can not
give a positive opinion on this question, as he has not seen
Smith's specimens and has so far been unable to confirm his
results. The drawings he gives of the mature spores in his
book (6) resemble such spores, but other of his drawings are
questionable. But even DeBary (2) does not deny that some
of the bodies Smith described might have been oospores, for he
says, "The warty bodies are possibly its oospores." In another
place in this same article DeBary also says: "Ever since the
oospores of a Peronospora were discovered, innumerable
searches have been made for those of Phytophthora. I have
myself looked for them in the stalks, leaves, flowers, fruit and
tubers of the potato. In July of the present year (1875), when
the fungus appeared in this district in sad abundance, I obtained
a very large amount of material for study and at the same time
secured the kindly assistance of two botanists experienced in
researches of this kind, Dr. Rostafinski and Dr. Stahl. But
again only negative results were arrived at." Since Smith's
time, Smorawski and others have claimed to have found the
oospores, but these claims always lack positive proof. How-
ever, most botanists probably believe with DeBary that they
will be found sometime. He said, "That they will be regularly
found somewhere or other is assumed, for our knowledge of the
habits of numerous allied fungi make this more than probable."
Smith stated that it was an easy matter to obtain the oospores
by merely placing a number of diseased leaves overlapping each
other in a moist chamber and examining them as they rotted
down. The writer has tried his method a number of times but
never succeeded in finding spores that were decidedly suspicious.
True, one frequently finds various kinds of rounded, usually
isolated, bodies in such leaves, some of which are apparently
spores of fungi and others merely encysted stages of the lower
animals. Even if one were to find the oospores under these
conditions, it would be a difficult matter to accurately trace their
development because of probable confusion at times with other
things. After considerable search in the dying and dead leaves
and stems, it finally seemed to the writer that the diseased
tubers offered the most likely place for the formation of the
326 CONNECTICUT EXPERIMENT STATION REPORT, IQCS-
oospores. Consequently these have been searched in all stages
of infection and decay and at various times of the year. While
some suspicious bodies have been seen from time to time, no
very definite evidence has been gained that the fungus produces
oospores even here. If they are formed in the tubers it is only
in the decayed parts, as the healthy tissue offers little opportu-
nity for their development and no suspicious signs have been
found there. Examination of tubers decayed from a dry
reddish brown rot usually shows the presence of the peculiar
short haustoria of the blight fungus and these seem to become
more prominent and develop thick, swollen walls with the
advance of the decay. Often two of these haustoria are seen
standing side by side in a cell, and while they indicate a living
mycelium, even in advanced stages oi rot and disintegration
of the tuber, nothing definite concerning any further develop-
ment of them or the mycelium has been made out. Resting
spores with thick walls and somewhat of the type of oospores
have been seen, but there was never any evidence that they
were formed from the mycelium of the blight fungus. The
potato tuber before its final dissolution in the ground is the
workshop of many different fungi, as well as of the lower
animals, hence the necessity of caution in forming decided
opinions of forms found there. These tubers finally, through
the work of the animal life, are more or less scattered through
the .soil, so that if oospores are formed they would secure more
or less of a local distribution in the soil, probably about the
time the blight appears in the fields.
Mycelial strains. In recent papers Blakeslee* has shown that
in a related family, Mucoraceae, certain species possess mycelial
strains, apparently of a sexual nature, that produce zygospores
only when these grow together. Securing artificial cultures
of the two strains, which he calls -|- and — , of such a species, he
was able to produce the zygospores at will merely by inocula-
ting the same cultural tube with both forms. In the study of
various downy mildews it has occurred to the writer that possi-
bly similar conditions are true for certain of these fungi, and in
our Report for 1904 this was suggested as a possibility for the
* Science, 19: 864-6. 1904. Proc. Amer. Acad. Arts Sci., 40: 203-321.
1904.
DOWNY MILDEW OF POTATOES. 32/
potato mildew. Some effort, as stated previously, has been
made to secure such strains in pure cultures and prove the
theory by cross inoculations, but as yet no evidence has been
secured in this way. While no positive proof has been gained
for this belief, there are yet certain facts, as given in the next
paragraph, that may be considered at least favorable to it.
In the first place the oospores of the Peronosporeae, like the
zygospores of the Mucoraceae, are not commonly found in nature.
There are species, other than the potato mildew, for which they
have never been found ; others for which they have been rarely
found; some for which they have been found only on certain
of their hosts ; and finally, some in which they are not uncom-
mon if looked for at the proper time and place. All of these
facts are in favor, rather than against, distinct mycelial strains
(heterothallic forms) except the last, which might indicate a
homothallic form (one which contains both antheridia and
oogonia on the same mycelium). Secondly, our culture experi-
ments with the Lima bean and potato mildews, both species
of Phytophthora, is in accord with this theory. The potato
mildew cultures never produced oospores under any con-
dition, possibly because there was but one strain present, and
our cultures of the Lima bean mildew ran to the production of
oospores, possibly because the cultures were obtained from
material containing both strains. The potato mildew cultures
often gave a very evident aerial growth of the mycelium and
conidiophores, while this development in cultures of the Lima
bean mildew was usually inconspicuous, though in nature its
conidial stage is much more prominent than that of the potato
mildew. Thirdly, Smith, in a drawing of the development of
his supposed oospores of the potato mildew, shows two different
mycelia. side by side, one producing oogonia and the other
antheridia. DeBary at first criticized this on the ground that
the oogonia and antheridia were not on threads in anatomical
relation with each other, but later, according to Smith, withdrew
this criticism. Smith, of course, may have shown in this draw-
ing something having no connection with the potato mildew,
yet in all of the drawings, seen by the writer, of DeBary (i)
and others showing the development of oogonia of various mil-
dews, the antheridia and oogonia are always figured on threads
having no connection with each other. It is true that only a
328 CONNECTICUT EXPERIMENT STATION REPORT, I905.
short piece of each thread is shown in these drawings, but it
is usually difficult to trace these further. In our study of the
Lima bean mildew effort was made to follow these threads as
far as possible, and the evidence, so far as obtained, pointed
to their independent origin, so that they could easily have been
borne on two different mycelia closely interwoven.
Delayed appearance of blight. It is not as yet definitely
known why the blight does not appear earlier in the potato
fields. The weather in May and sometimes in early June is as
favorable for its development as that of July and August, when
it does first appear. On the face this would indicate that the
germs for infection were not generally available so early in the
year, and yet this is the very time when the mycelium* in the
seed tubers underground is best situated for producing the
conidial stage on them. DeBary possibly explains this delayed
appearance in the following statement: "From large exper-
ience I consider it probable that Phytophthora grows more
easily on a plant at the height of its development than on young
stalks and leaves. It would be interesting, but not easy, to
establish this clearly by experiment." In the writer's experi-
ments already given it was found possible to easily infect young
leaves and stems, but whether the subsequent development of
the fungus was more or less vigorous than on old tissues was
not a point at issue. Possibly the point previously suggested
in this article explains the late appearance; viz., that the
mycelium from primary infections on young, rapidly growing
tissue remains localized until after vegetative growth of the
host ceases and then renews its activity on the appearance of
favorable blight weather. If the primary infections, however,
usually take place, as the writer believes, by contact of the
leaves with the ground, this is best accomplished in the full
growni plants. The young plants are rigid and shoot straight
up out of the ground, and by the time they have attained any
* According to DeBary's and our experience the mycelium will produce
its conidial stage only in the living tissues of the tubers, but Massee, on
the other hand, reports this stage in the old diseased tubers even a year
after they have rotted ; if the fruiting stage found by him was developed
by the germination of oospores, this apparent conflict of observations
might be explained.
DOWNY MILDEW OF POTATOES. 329
considerable growth and are likely to lop over on the ground,
the wet weather of the spring is largely past. If it were known
definitely that oospores were produced, the most feasible expla-
nation would be that these did not germinate until the wet
weather of July and August and then their zoospores in the
moist earth infected the leaves that were washed down in con-
tact with them by the rains. This would agree perfectly with
what the writer has been able to ascertain so far, of the primary
infections in the fields.
Literature.
The botanical and general agricultural literature dealing with
the potato mildew is perhaps more extensive than that for any
other fungus. There are given here merely a few articles, to
which reference has been made in the preceding discussions.
1. DeBary, A. Recherches sur le developpement de Quelques Champig-
nons Parasites. Ann. Sci. Nat. Bot. IV, 20: 5-148. 1863.
[Illustr.]
Deals in this paper especially with the Peronosporeae and gives
considerable information, with illustrations, of the potato mildew.
2. DeBary, A. Researches into the Nature of the Potato Fungus,
Phytophthora infestans. Journ. Bot., n. s., 5: 105-26, 149-54. 1876.
[Illustr.]
Gives in this excellent paper the life history of the fungus, so
far as known, and treats especially of his studies made for the
Roy. Agr. Soc. of England and a criticism of Worthington Smith's
so-called oospores.
3. Massee, G. Diseases of the Potato. Journ. Roy. Hort. Soc, 29:
139-41- 1904.
Gives short general account of the mildew and makes two rec-
ommendations, based on field and laboratory observations, for
keeping it in check; namely, collection of the diseased and old seed
tubers at harvest time and use of seed tubers showing no sign of
disease.
4. Matruchot, L. and Molliard, M. Sur la culture pure du Phytoph-
thora infestans DeBary, agent de la maladie de la pomme de terre.
Bull. Soc. Myc. Fr., 16: 209-10. 1900.
Note that they have been able to grow this fungus on living
and sterilized media in pure and artificial cultures.
5. Matruchot, L. and Molliard, M. Sur le Phytophthora infestans.
Ann. Myc, i: 540-3. 1903.
Give further more extended notes on the artificial cultures of
this fungus on living and sterilized slices of potato and pumpkin;
330 CONNECTICUT EXPERIMENT STATION REPORT, I905.
note that the fungus does not discolor the living plugs of potato
if grown pure ; found no oospores.
6. Smith, W. G. Potato Disease, I, II. , Diseases of Field and Garden
f Crops : 275-329. 1884. [lUustr.]
Makes an extended report on Phytophthora infestans in both its
active and passive state; discusses in detail his discovery of
oospores.
7. Smorawski, J. Zur Entwicklungsgeschichte der Phytophthora infes-
tans (Montagne) DeBy. Landwirthsch. Jahrb., 19: 1-12. i8go.
[Illustr.]
Gives a general account of the investigations of others and
records observations and experiments of his own; describes and
illustrates immature oospores that he connects with this fungus.
8. Wilson, A. S. Potato Disease and Parasitism. Trans. Proc. Bot.
Soc. Edinburgh, 19: 656. 1891.
Explains his mucoplasm theory, by which he accounts for the
spread of the blight.
PLATE XIII.
Apple.
a. Fruit Speck, p. 264.
Lima Bean.
b. Leaf Blight, p. 265.
FUNGI OF APPLE AND LIMA BEAN.
PLATE XIV.
Catalpa.
a. Leaf Spot, p. 266.
Celeriac.
b. Leaf Spot, p. 267.
FUNGI OF CATALPA AND CELERIAC.
a. Leaf Scorch, a physiological trouble, p. 267.
Nectarine.
b. Scab, p. 268.
DISEASES OF MAPLE AND NECTARINE.
PLATE XVI.
■**'>!**' "
a. Showing upward progress of disease by cliaracter of leaves.
Diseased. Healthy.
b. Longitudinal and cross sections of stems, showing how tissues are injured.
WILT OF OKRA, p. 268.
PLATE XVII.
a. Onion Brittle, showing peculiar malformation of leaves, p. 270.
b. Bacterial Black Spot of Plum, p. 273.
DISEASES OF ONION AND JAPANESE PLUM.
PLATE XVIII.
Spinach.
^' 'M'-- #
wn
m
I^^R
Wi
W^/
^
^-»^!
^A|^^
**■."•
-in
>
t
'^-
^"ggtfg
*%iivft??S?t"' iT^^M^^
r
b. Powdery Mildew, p. 276.
FUNGI OF SPINACH AND STRAWBERRY.
PLATE XIX.
a. Cultures of the fungus on potato agar, showing sclerotia.
b. Showing how the fungus injures base of stems.
DAMPENING OFF FUNGUS OF YOUNG TOBACCO PLANTS, p. 276.
PLATE XX.
a, mycelium; b, antheridium; c, oogonium; d, oosphere; e, oospore. Figs.
1-7, showing character of myceHum. Figs. 8-21, antheridia and oogonia and
their development. Figs. 22-25, mature oogonia and oospores. Magnified
about 600 diameters.
DEVELOPMENT OF MYCELIUM AND OOSPORES OF LIMA BEAN MILDEW,
Phytop]itlio)-a J'/iaseoli .
PLATE XXI.
• •t
a. Diseased seed containing oospores, except healthy one at **, pp. 292, 297.
b. Showing injury to young stems and leaf, p. 281.
DOWNY MILDEW OF LIMA BEAN, Phytophtlwya Phascoli.
PLATE XXII.
a. Showing- mildew in young and old state on pods.
b. Showing portion of infected pod enlarged two diameters.
DOWNY MILDEW OF LIMA BEAN, Pbyfophthora P/iascoli, p. 280.
PLATE XXIII.
h^
a. Showing primary infection from contact witli ground, p. 309.
b. Artificial infection of the mildew on cut surface of tuber, p. 318.
DOWNY MILDEW OR BLIGHT OF POTATO, Phytophtlwra infcstaus.
PLATE XXIV.
a. Two lower and tip of third leaf killed by fungus, lo days after inoculation, p. 315.
b. Central diseased shoot grown from an inoculated tuber, p. 307.
INFECTION EXPERIMENTS WITH Phytophtlwra infestans.
PLATE XXV.
a. On plugs of living potato, a, check.
b. On corn meal.
c. On pumpkin agar.
ARTIFICIAL CULTURES OF Phytoplithora iufcstans, p. 317-
Agrictaltiara^
CoUegre
State of Connecticut
REPORT
OF
The Connecticut Agricultural
Experiment Station
FOR THE YEAR I9O6
PART V.
REPORT OF THE STATION BOTANIST
CONNECTICUT
AGRICULTURAL EXPERIMENT
STATION
REPORT OF THE BOTANIST,
G. P» CLINTON, ScD,
I. Notes on Fungous Diseases, etc., for 1906, p. 307.
II. Experiments to prevent Onion Brittle, p. 332.
III. Dry Rot Fungus, Mertilius lacry7nans (Wulf.) Schum., p. 336.
IV. Root Rot of Tobacco, Thielavia basicola (B. & Br.) Zopf, p. 342.
ISSUED MAY, 1907
PART V.
REPORT OF THE BOTANIST FOR 1906.
G. P. Clinton, Sc.D.
I. NOTES ON FUNGOUS DISEASES, ETC., FOR 1906.
GENERAL NOTES ON DISEASES PREVIOUSLY REPORTED.
During the year 1906 fungous diseases as a rule were not
especially troublesome in Connecticut. In this respect it was
like the preceding year, though the distribution of the moisture
was somewhat different. In 1905 the drier part of the growing
season came before August, and the moister period was during
August and September; but in 1906 the moist weather came
in June and July, while the latter part of the season was
dry. During last June there was a rainfall of 5.14 inches,
which was over two inches in excess of the average rainfall of
the past 34 years; July also gave a slight excess over the
average. This abundance of moisture was favorable for start-
ing certain fungous troubles, but as it came in thunder showers,
without especially cloudy or foggy weather, and as August and
September were largely free from rains, the fungous troubles
on the whole did not become prominent. A peculiarity of the
season, however, was the large number of leaf scorch or similar
troubles, due to peculiar weather conditions dliring June and
July.
The diseases mentioned in the following paragraphs are old
troubles that were unusually serious or that were less injurious
than usual. They are, grouped according to their hosts, as
follows :
Apple. Sooty blotch, Phyllachora pomigena, was very prom-
inent the past fall on apples all over the state. This is now one
of the most serious fungous troubles of the apple in Connect-
icut. While the fungus was especially conspicuous in the small
3o8 CONNECTICUT EXPERIMENT STATION REPORT, I906.
orchards, and on the few trees kept by each farmer for home
use, it also did more injury than usual in the larger orchards,
even when they had been sprayed. One could scarcely find any
good specimens of Greenings, in the fall and early winter
markets, because of blemishes by this superficial parasite.
Black rot or canker, Sphaeropsis Malorum, was also frequently
sent to the Experiment Station for identification.
Asparagus. A single grower in Norwalk reported one of
his beds seriously injured by the rust, Puccina Asparagi, but
the writer did not have opportunity for determining whether
or not this trouble was common.
Beans. The downy mildew of the Lima beans, Phytophthora
Phaseoli, did some injury, but was probably not quite so injur-
ious as the previous year. A grower in Southport, however,
reported a crop practically destroyed by it. The oospores of
this fungus were again found, thus indicating that they are
probably not so uncommon as supposed. Anthracnose of
string beans, Colletotrichum Lindemiithianum, was more com-
mon and injurious than for several years.
Cucumber and muskmelon. On the whole these plants suf-
fered less than usual from fungous attacks. The growers even
had a fair crop of muskmelons. More or less injury, however,
was done by the downy mildew, Peronoplasmopara Cubensis,
and the leaf mold, Altentaria Brassicae var. nigrescens.
Grape. The black rot, Guignardia Bidwellii, and possibly
other rots, were considerably more injurious than usual. Spray-
ing failed to satisfactorily control this trouble in some cases.
Onion. There was considerable complaint of poor onions in
1906. Most of the trouble was due to the character of the
season and insects. Fungi were responsible to a less degree
in some cases. There seems to be a tendency of onions grown
for seed in the onion districts of the state to deteriorate. The
cause of this decline, however, is not yet satisfactorily deter-
mined, though in some seasons fungous troubles seem to be
largely responsible. Onion brittle was more conspicuous this
year than last, in the infected fields in the neighborhood of
Guilford, since it seems to be a soil trouble that increases in
extent each year. A discussion of this disease, including experi-
ments made to control it, is given elsewhere in this report.
NOTES ON FUNGOUS DISEASES FOR I906. 309
Peach. While last year there was considerable injury from
the brown rot, Sclerotinia friictigena, this year the peaches were
almost entirely exempt from it. Some little rot appeared at
first on the early varieties that are most subject to decay, but
the weather as a whole was so fair and dry during the picking
season that the crop was conspicuous for its fair size, good
quality and freedom from rot.
Pear and qviince. There were a few complaints of the bac-
terial blight, Bacillus amylovorus, on pear, and one grower
informed the writer that he had never seen this trouble so
injurious to his quince trees as it was this year.
Potato. Tip burn and early blight, Alternaria Solani, were
more common than usual. The wet weather of June and July
came at a time most favorable for the development of the early
blight, while the sudden alternation of bright, hot days with
those of abundant rainfall was responsible for most of the tip
burn, rather than any long period of dry weather. There were
some unusual cases of injury to potato leaves in June that were
hard to account for except on this basis. The late blight,
Phytophthora infestans, because of the wet weather of June
and July appeared this year considerably earlier than the pre-
vious year, the first specimens being found on July 23rd, as
compared with August nth, in 1905. However, the dry
weather of August and September prevented the fungus from
causing even the ordinary damage. There was a little injury
to the foliage of the early potatoes, where the vines grew rankly,
and a little rot shov?ed in their tubers; but the injury was soon
checked by the dry weather. Although we had unusual oppor-
tunity for learning of injury in late potatoes, there was abso-
lutely no complaint of rot anywhere in the state. Without
question the late blight did the least damage in the state this
season of any of the five years the writer has had it under
observation.
Raspberry. The wilt of raspberry, Leptosphaeria Coniothy-
rium, which has been complained of in a general way for some
years past, was unusually prominent during June and July of
the past season, since complaints were received from a number
of places scattered! over the state of the wilting of the half
matured fruit. Further mention of this trouble is made under
3IO CONNECTICUT EXPERIMENT STATION REPORT, I906.
new diseases because of a new discovery, concerning its inocu-
lation by insects, which was brought out in our study of the
trouble. Aside from the wilt, this was a very good year for
raspberries.
Tobacco. The early spring seems to have been rather
unfavorable for tobacco seed beds, since dampening off and root
rot troubles were more conspicuous than usual. The' weather
for curing tobacco in the barns at the end of the season, how-
ever, was so unusually favorable that pole burn did no damage
whatever, and the tobacco cured much earlier than usual.
NEW DISEASES.
Each year a certain number of fungi occurring on economic
plants are observed that have not been reported previously in
this state, or old species are found on new hosts, or some new
point is made out in the life history of a fungus. Such data
are recorded in the following paragraphs. Some of the fungi
briefly mentioned, though of little economic importance at
present, may eventually become conspicuous enough for more
extended notice later. By recording from time to time these
new observations, we aim to have finally a complete survey of
all the diseases of cultivated plants of the state. Most of the
troubles reported this year are entirely new, special note being
made of the exceptions. As usual, we distinguish between
those diseases caused by fungi and bacteria, and physiological
troubles caused by unfavorable environment (such as heat,
moisture, wind, cold, etc.). The common names of the latter
class are printed in italics, while those of the former are
printed in small caps, followed by the scientific name of the
fungus.
APPLE, Pints Mains.
Winter Injury and Canker, Sphaeropsis Malorum Pk. Plat6
XVII, a. We have reported before injuries due to the severe
cold of winter, and those caused by the canker fungus, but last
spring Dr. Britton called to our attention a peculiar trouble of
apple limbs that seemed to be due to a combination of these
causes. The specimens were from an apple grower of West
Hartford, who first noticed the trouble while pruning his trees.
The specimens sent to the Station for examination showed large
NOTES ON FUNGOUS DISEASES FOR I906. 3II
dead sunken areas in the bark, usually starting from dead twigs,
and apparently caused by the canker fungus, since it was in
fruiting condition on some of the specimens. Some of the
smaller of the injuries had been outgrown by the development
of a new growth of bark beneath. Another and more peculiar
feature of the trouble was the enlargement of the limbs into
somewhat fusiform swellings, as shown in the illustration. In
some cases several of the swellings followed one another on
the same limb. These enlargements generally showed a greater
swelling on one side than on the opposite, and often the bark
was split down the more swollen side. Cross and longitudinal
sections showed that the swellings were apparently the result
of severe cold, which had injured the limbs unevenly along the
branch, as shown by the blackened wood on the injured portion.
The winter injury was most severe on the side of the limb least
swollen, and had restricted the growth of the woody layers the
following years, while on the swollen side the wood had made a
greater growth, as shown by the larger annual rings. The
growth of the bark had been affected, too, by the winter injury,
but was thickest on these swellings, and as a rule had made a
greater growth on the injured side. The longitudinal cracks
in the bark apparently had not been caused by winter injury,
but by the abnormal and excessive growth of the wood on the
more swollen side of the branch. The cracks only extended
through the outer bark, as a healthy growth of new bark beneath
was healing them over. Here, then, we have a case of winter
injury to limbs acting irregularly (possibly due to unequal
maturity of wood at the time of the injury) so that as a whole
it stimulated the bark to unusual activity at the injured places,
the wood on one side of the limb being so injured as to retard
growth the following years, while on the other side the injury
was so slight as really to act as a stimulus to unusual growth.
The cankered areas occurred on the sides most injured, and
apparently the canker fungus largely got a start here through
the smaller twigs that had been entirely winter killed.
BEANS, Phaseohis vulgaris.
Leaf Scorch. During the early summer Mr. Andrew Ure of
Hamden called the writer's attention to a field of string beans
that had been injured suddenly by some cause that rendered
312 CONNECTICUT EXPERIMENT STATION REPORT, I906.
many of the plants worthless. The injury resembled somewhat
the bacterial blight of this host, but an examination of the
injured tissues 'failed to reveal bacteria or any fungus as the
probable cause. The leaves in some cases were entirely dead,
but in others only a part of the leaves were injured. The irreg-
ular area of dead tissue of the leaves partially injured was
usually separated from the healthy by a reddish purple border,
but there was no water-soaked appearance, as is usually the
case with the bacterial trouble. Examination failed to reveal
any more probable cause than leaf scorch, due to bright, warm
weather suddenly following a very violent rain storm, with high
winds, which occurred shortly before the trouble was first
noticed. A peculiar feature, however, was that some other
bean fields in the neighborhood did not suffer from this trouble.
This, while difficult to explain, might have been due to the
variety of beans, their age, or unknown differences in the soil
conditions.
CARNATION", Dianthus Caryophyllus.
Spot^ Alternaria sp. This disease was called to the writer's
attention by Mr. Walden of this Station, who collected speci-
mens in the greenhouse of Mr. S, Perry Beers of Greenfield
Hill. Mr. Beers had obtained his carnations already rooted
from another greenhouse, where this trouble was also present.
In a few cases the disease was severe enough to kill the plants
outright, but usually the injury was limited to the leaves
dying at their tips or to the whole top of the plant dying as the
result of a girdled area beneath. Generally the injured places
were of a whitish color having a rather inconspicuous black
growth of the fruiting stage of the fungus. The only mention
of .a similar disease of carnation caused by Alternaria that the
writer has seen is that made by Mr. Orton in the Yearbook of
the U. S. Department of Agriculture for 1905 (p. 611). Mr.
Woods, of the Department of Agriculture, who has made a
special study of the fungus, in a recent letter to the writer
says : —
"The disease is quite serious on the softer-leaved varieties, such as
those of the Lawson type, especially the Lawson and the Enchantress.
The disease behaves very much like the other Alternaria diseases,
especially the one on the violet, attacking not only the leaves, but the
NOTES ON FUNGOUS DISEASES FOR I906. 313
Stems, and cutting the plants back very seriously in many cases. In
fact, I have seen w^hole houses of carnations practically stripped of
their leaves and losing a large part of the top. Plants grov^rn out of
doors, exposed to rain and dew, especially in the night, are very subject
to the disease and suffer seriously when the plants are moved into
the house. It is, of course, then rather difficult to free the plants
of the disease without cutting them back very severely and spraying
them thoroughly with soap Bordeaux. The proper treatment is to
spray the plants from the time they are set in the field until the time
they are moved into the house, keeping the young growth well covered
with Bordeaux and continuing the treatment after the plants are in
the house until they become well established. If the plants are grown
in the house all of the year and the leaves are not allowed to remain
wet over night, the disease seldom, if ever, does much injury."
CAULIFLOWER, Brassica oleracea.
Black Rot_, Pseudomonas campestris (Pammel) Smith.
While the black or brown rot of cabbage, turnips and allied
plants is not a rare bacterial trouble, it has never been definitely
reported in this state. From occasional complaints received
from growers, there is little doubt that, while not reported
before, it has been present for some time, doing more or less
injury. Last October the writer made his first collection of
this disease from some cauliflowers grown on the Experiment
Station grounds. The heads were blackened and blasted, much
as if injured by frost. There was also complaint of a rot
of turnips on a Hamden farm which no doubt was also of this
nature, though no specimens were seen. The black rot bacteria
usually enter their hosts through injured tissue or the water
pores at the margin of the leaves. The bacteria develop abun-
dantly in the fibro-vascular vessels, working from the veinlets
into the large veins and ribs, which are turned black as a result
of the invasion. Finally they may reach the stem, and cause
a more general injury. As a result of the clogging and disease
of the bundles, the water supply is gradually cut off from the
fleshy tissue, and the leaves turn yellow, wilt, and finally die.
In diseased cabbage, the bacteria sometimes work their way
directly from the infected leaf through adjacent leaves, causing
an internal rotting while the head from the outside may appear
sound. When this disease appears in a field, rotation with non-
cruciferous crops should follow for a few years. The diseased
314 CONNECTICUT EXPERIMENT STATION REPORT, I906.
plants should be destroyed, and rubbish from the plants should
never get into the manure pile. It has lately been shown that
the bacteria causino- this disease can be carried on the seed and
cause infection of the young plants, so care should be, used to
obtain seed from healthy plants.
CORN, Zea Mays.
Black Mold, Cladosporium Zeae Pk. This is a fungus that
sometimes appears conspicuous on both sweet and field corn,
though it is not strictly a parasite, and possibly not directly
the cause of any injury. It shows as an olive-black growth on
the kernels, usually at the tip of the ears. Apparently it devel-
ops on improperly matured or injured kernels, and makes this
injury appear more conspicuous. When the seed corn is not
properly dried before storage or is left too long stacked in
damp places, the fungus probably extends the injury. While
Peck described this fungus as a distinct species, it is quite pos-
sible that it is not distinct from th"e common saprophytic black
mold, Cladosporium herbarium (Pers.) Lk. The renewed
interest taken by some of our growers in the selection of seed
corn is likely to call their attention to the fungus as one of the
blemishes of perfect seed ears, especially of the sweet corn.
GRAPE, Vitis sps.
Bitter Rot^ Glomerella rufomaculans (Berk.) Spald & von
Schr. This fungus has previously been found in this state on
the apple and pear, but not until the past season on the grape.
On the apple it certainly does not do the damage here that it
does further south, and possibly its injury to the grape is also
inconspicuous. Just how common the grape bitter rot is in
the state, however, cannot be stated at present, as usually all
the rots of grapes are indiscriminately called the black rot.
This season it was found in one place at Westville, where it
seemed to be the cause of considerable decay, and a few berries,
chiefly rotting from other causes, were also found among speci-
mens sent from New Haven and New London. The spores
ooze out in small pinkish masses, and by these the rot can often
be told with the naked eye from the more common black rot.
NOTES OX FUNGOUS DISEASES FOR I906. 315
Blue Mold^ Penicilliiim glaucum Lk. A trouble which has
not been reported before, but which is common, is that caused
by the ordinary blue mold found on cold storage grapes,
especially towards the end of their season. The fungus attacks
the grapes that are more or less bruised by packing or handling ;
also where the grapes are overripe it seems to gain entrance
at their stem end. Along the cracks in the skin the fruiting
stage of the mold shows at first as a whitish, but soon as a
dusty, blue-green growth. Of course all such berries are worth-
less, and the spores from these form the means for a much
more general spread of the trouble through the basket. While
usually but few grapes are injured, if sold soon after removal
from cold storage, after they are out some time the trouble
may even spoil the whole basket. Some of the baskets offered
for sale last fall had as high as a third of the grapes spoiled in
this way. Another quite similar blue mold, (Aspergillus
glaucus) may also at times be partly responsible for this decay,
as one of the cqltures made from the grapes showed that it was
present.
Shelling and Rot. One case of serious shelling off of
Niagara grapes, about the time of maturity, was reported from
New London, and the same variety at the Experiment Station
was similarly injured. As in both of these cases the grapes
rotted more or less, especially after falling to the ground, it is
a question whether or not some fungus might have been par-
tially responsible for the trouble. It is generally conceded,
however, that shelling (without rot) is the result of non-para-
sitic causes. Among the non-parasitic causes the peculiar sea-
sonal conditions of the year, already mentioned elsewhere, which
apparently caused an unusual number of physiological troubles,
may have been the chief cause of this trouble. The grapes on
the ground in time showed the fruiting stage of a species of
Macrophoma. This fungus probably occurred on them as a
saprophyte ; at least Macrophoma flaccida (on the fruit) and
Macrophoma rimiseda (on the branches), which agree some-
what closely with the species reported here, are usually con-
sidered non-parasitic species. The shelling of Niagara grapes
has been mentioned once before, by Sturgis, in the Experiment
Station Report for 1896, p. 278. Since, through oversight, this
3l6 CONNECTICUT EXPERIMENT STATION REPORT, I906.
was not included among the troubles mentioned by the writer
in his general report of diseases, made in 1903, and since it was
probably a common trouble the past season, the following is
quoted from Sturgis' article: —
"Shelling grapes, at least in the case of green varieties, show a
peculiar though indistinct mottling of the surface; the skin is abnor-
mally thick, and the whole berry, therefore, feels harder than healthy
berries at the same stage of development; a section of a diseased
berry shows a narrow brown zone just beneath the skin; the taste of
shelling grapes is noticeably insipid as compared with the tart, astrin-
gent flavor of the unripe but healthy fruit; finally, the woody tissues
of the stem which enter the fruit and, in the case of sound berries,
remain attached to the stem when the berry is pulled off, are so far
weakened in the case of shelling grapes that the weight of the berry
is sufficient to cause them to separate from the stem, and the berries
fall to the ground, leaving the ends of the stem perfectly even, 'as if cut
with a knife.' This dropping of the fruit from two to three weeks
before maturing, is a characteristic symptom of shelling, and may result
in very serious loss, a loss emphasized by the fact that the trouble does
not confine itself to certain bunches on a vine, leaving others unaffected,
but affects portions, generally the end, of every bunch.
After a most exhaustive consideration of all the possible causes of
shelling, Lodeman concludes that neither insects nor fungi are to be
considered as a primary cause of the trouble; that the condition of
the soil, apart from the supply of available plant food, does not exercise
any marked influence on the degree of shelling; that meteorological
conditions are not primarily responsible for it ; and that it is not due
to a lack of phosphoric acid. Among the agencies which may increase
or favor the diseased condition, Lodeman mentions parasitic fungi,
which weaken the function of the leaves ; a weakening of the plant due
to overbearing; the drawing of nourishment from the fruit by over-
production of wood; an excessive supply of nitrogen, emphasized by
too much tillage; long drought or excessive rains following drought;
and a poorly developed root system, resulting in a general weakening
of the plant. The condition of the food supply as regards potash
seems to be the only remaining factor to be considered, and Lodeman
is inclined to attribute the primary cause of shelling to a lack of that
element. This view is in a measure substantiated by observation and
experiment."
OATS, Avena sativa.
Yellow Leaf. This trouble was first seen at Portland, the
second week in June. During June and July it was noticed in
almost all the oat fields examined, and so must have consider-
ably reduced the yield. The leaves, especially the lower, became
NOTES ON FUNGOUS DISEASES FOR I906. 317
a sickly yellow, and many finally died prematurely. In some
respects this trouble resembled the bacterial disease that occa-
sionally occurs in the early summer in the oat fields of the
West; but the leaves lacked the water-soaked appearance of
that disease, and on examination failed to show any bacteria
present. The trouble apparently resulted from unfavorable
weather conditions, possibly aggravated by some root disease,
though the few examinations made of the roots failed to show
any suspicious fungus at work there. June and July had many
heavy rain storms suddenly followed by bright hot days, and
these sudden changes, as in other cases already mentioned,
probably caused the injury. The same trouble was seen to a
less degree on a number of other grasses, both wild and
cultivated.
PEACH, Prunus Persica.
Leaf Fall. Another physiological trouble called to the
writer's attention by J. H. Hale, of Glastonbury, at the annual
meeting of the Connecticut Pomological Society, was the
unusual loss of the peach foHage in his orchard during August
and September. Many of the leaves turned yellow, finally
dying and dropping off. In some cases there was some shot-
hole injury, but otherwise nothing to indicate that any fungus or
insect was the cause of the defoliation. Conversation with a
number of other large peach growers brought out the fact that
this defoliation was a common trouble this year in the state.
Both bearing and young trees were affected, but certain vari-
eties more than others. Alberta and Late Crawford were
among the varieties that suffered most. Some of the growers
were inclined to believe that fungi or insects were the cause
of the trouble. From their descriptions, however, it seems that
neither of these agents, if responsible, was at work on the
leaves themselves. The San Jose scale, if very bad on a tree,
may cause partial defoliation, but there was no likelihood that
it was unusually prominent in the orchards complained of. It
is barely possible that such denudation of the trees might fol-
low root injury. There is no fungus trouble in the state, how-
ever, that has been known to act exactly in this way. The
crown gall and the crown or foot rot are the only root troubles
so far known here, and' it does not seem plausible that either
3l8 CONNECTICUT EXPERIMENT STATION REPORT, I906.
of these was responsible for so general and unusual a trouble.
Among the insects the peach borer is the only one that might
be suspected, but if this was responsible, it would undoubtedly
have been detected by the growers, and its injury is not quite
like that described here. Everything considered, it seems prob-
able that this was also one of the seasonal physiological troubles
that were unusually common this year. The wet months of
June and July no doubt developed a tender and luxuriant leaf
growth on the trees, and the bright, dry months of August and
September offered such different conditions (especially if the
roots still showed any effects of winter injury from the cold
winter of 1903-04) that the evaporation of moisture from the
leaves became disproportionate to the amount supplied by the
roots, and the defoliation of the older leaves gradually followed
as a consequence.
PEONY, Paeonia sp.
Root Injury or Rot? Plate XVII, b. In September com-
plaint was received from Southington of a root rot of peonies,
which had gradually become quite serious. In writing of this
trouble, the grower, Mr. H. R. Whitney, said: "When the
plants first became established they were very beautiful, but
since this disease has come upon them they do not amount to
anything, some not even blooming. The first sign noticed is a
discoloration of the leaves, turning to a chocolate color, accom-
panied by wilting, and finally death of the stalk. Sometimes
the wilting occurs without any discoloration ; the roots seem to
rot to pieces at the surface of the ground much after the man-
ner of the rootstock rot of iris (which, by the way, is very
prevalent hereabouts, and all our iris beds are seriously affected
by it). These peonies were set on a sloping hillside facing the
north, and the lowest plants were the first ones affected. The
disease has now spread to all. They have always had good
care. I am now going to transplant them to higher ground, in
fresh soil, and see what this will do."
I am not certain about the cause of this trouble. The speci-
mens sent for examination showed a dry, rather than a wet
rot, though possibly this was because they had dried out some-
what. The statement that the iris on' his grounds was being
NOTES ON FUNGOUS DISEASES FOR I906. 319
injured by a bacterial rot might indicate that the same agent
was at work on the peony. An examination of the roots, how-
ever, did not lead the writer to the conclusion that bacteria
were responsible for the injury, though some bacteria were
present in the tissues, and cultures made from the diseased
parts usually gave mixed growths of bacteria and fungi.
Microscopic examination of the diseased tissues showed that
there was present the sterile mycelium of some fungus that
looked as if it might be the cause of the trouble. The fungus
was peculiar because of numerous roundish, dark reddish
brown chlamydospore-like bodies that occurred in the threads.
Cultures from this tissue seem to indicate that these were
possibly threads of a Torula developing under unfavorable con-
ditions. In this case the fungus was apparently only a sapro-
phyte that developed in the tissue after the injury, rather than
its cause. A peculiarity of the trouble, at least in the specimens
sent for examination, was the sharpness with which the healthy
tissue was marked off from the diseased, as shown by the
lengthwise section of the root in the illustration given here.
This may indicate that the trouble was not the result of bac-
terial or fungous attack, but possibly a winter injury. Usually
the injury was on one side of the root, but in some cases it
extended up into the interior, with white healthy tissue on either
side. Mention of this trouble has not been found in the liter-
ature of plant diseases, though probably it has not entirely
escaped observation before. Further study of injured plants
is needed to determine definitely the cause.
PINE, Pinus sps.
Leaf Blight^ Hypod'erma Desmazierii Duby. This caused
the pine needles to die from the tip inward, changing the normal
green color to a reddish brown, and in time to a grey brown.
On the lighter areas the spore stage of the sac fungus which
causes the injury developed as small, longitudinal black lines.
The fungus does more or less injury to the large pitch pine
trees, Pinus rigida, in this state, but just how much is not
known. Undoubtedly it causes in time a premature defoliation
of the infested leaves. No complaint has been made in this
country of the fungus, though in Europe Tubeuf & Smith men-
3 20 CONNECTICUT EXPERIMENT STATION REPORT, I906.
tion a similar species on white pine as doing considerable
injury.
RusT^ Peridermiuni acicolum Und. & Earle. During the
spring, complaint was received of a fungus injuring the leaves
of the pitch pine on an estate at South Manchester. ' As the
owner wished to develop the young native trees into a pitch
pine grove for landscape effect, she was anxious that no seri-
ous injury be done by this fungus. The writer made a special
study of the fungus, with the result that some new features of
its life history were brought to light. The fungus forms on
the leaves fragile, tongue-shaped, whitish receptacles filled with
orange-colored spores. By the first of July these had largely
disappeared, as the fungus did not spread further on the pine
leaves. It was found that this stage was merely the aecial stage
of another rust (Coleosporium Solidaginis) that is common on
goldenrods and asters. In July, following the disappearance of
the rust on the pine leaves, this other rust became very abundant
on the leaves of Solidago rugosa in this forest, especially where
these plants were close to the infected pines. The writer was
also able to produce the rust on an indoor specimen of Solidago
rugosa by infecting it with spores taken from the pine leaves,
thus conclusively proving their relationship. The rust at South
Manchester appeared chiefly on the young trees six to fifteen
feet high, whose limbs in many cases reached the ground.
Some few large trees with no limbs near the ground were not
at all infected. In order to prevent the spread of the trouble,
at the suggestion of the writer, the young trees were trimmed
of their lower branches, and the goldenrod, especially under the
trees, was all cut off. In this way it was hoped to prevent
any large amount of reinfection of the pine leaves from the
rust on the goldenrod another season. The writer hopes to
make a more detailed account of his study of this fungus
elsewhere.
Winter Injury f The state forester, Mr. Hawes, recently
had called to his attention a trouble of white pine, Pinus
Strohus, at Windsor. The injured trees were scattered through
the forest, and some were of large size, so that their death
meant considerable financial loss. The injury first showed in
the death of the leaves on the uppermost branches, but gradu-
NOTES ON FUNGOUS DISEASES FOR I906. 32 1
ally progressed downward until the whole tree was dead. An
examination of the injured and dead trees by Mr. Britton, the
entomologist, showed that while some were infested with a
number of borers, these usually confined their attention to the
dead or dying parts of the trunk, and were not species liable
to directly cause such injury. The writer saw several badly
injured trees (but still possessed of a living trunk and some
green leaves) which had blown over, and an examination of
these showed in every case that the roots were all dead except
a few small and apparently new ones near the surface of the
ground. This plainly indicated that the injury was primarily
one of the roots. At first we were inclined to believe that the
roots had been winter killed, but an examination showed that
the mycelium of some hymenomycetous fungus was present in
the dead roots and to some extent on the surface of the living.
This fungus was not determined, as its fruiting stage was not
present at the time of the examination, in March. Of course
it is possible that the fungus was present merely as a saprophyte.
A similar injury in Massachusetts was recently called to the
writer's attention by Professor Stone, who after a thorough
study has attributed it to winter injury.
EASPBERRY, Rubiis sps.
WiLT_, Leptosphaeria Coniothyrium (Fckl.) Sacc. Plate
XVIII, a. This trouble has been mentioned before in the
Reports for 1903 and 1904, but this year there were morecom-
plaints of serious injury from it than any previous year. A
more thorough study of the trouble has developed a new point
in its life history. Apparently the very wet weather of June
offered favorable conditions for the development of the fungus,
as it began to be quite conspicuous in its injury in the fruit
about the middle of the month. At this time the disease showed
on a few of the young canes, which gradually wilted from the
top as if they had been injured below in cultivation. Examina-
tion of these showed no such injury, but rather a rot at the base
or under the ground apparently due to the wilt fungus, though
not in a fruiting condition to fully identify it. Cankered areas
(as described by Stewart, of the Geneva, N. Y., Station, who
23
322 CONNECTICUT EXPERIMENT STATION REPORT, I906.
has made a special study of this trouble) may also occur on
various parts of the plant, and by girdling produce a wilt of
the parts above. On the fruiting or dead canes the fungus
usually appears more generally distributed in its fruiting con-
dition. From minute imbedded receptacles in the bark large
numbers of the spores are shed out on the surface as a dark
reddish brown coating. On the pruned canes the fungus often
gains entrance through the cut ends, killing the tips and pro-
ducing its fruiting stage on the dead tissues. The most serious
injury shows on the green, but nearly full-grown berries,
which begin to wither and diy up about the middle of June.
This usually occurs so prominently and suddenly as to alarm
the grower, who has not previously noticed the trouble, as
indicated by the following letter from Mr. W. B. Eastman of
Bethel: — "This a. m. I noticed that many of the berries
throughout the entire field were dying. I am afraid that the
entire crop will be lost should the dying continue."
The writer had previously had this drying up of the berries
called to his attention, and had attributed it to the fungus at
work in an obscure way at the base of the plants, or in under-
ground parts, as usually there was no evidence of it on these
canes above ground. These plants at Mr. Eastman's were
bearing for the first time and showed, as a whole, good vigorous
canes except for the wilting of the fruit. There was a
little of the wilt fungus present on old stems, and a few new
ones were dying from it, but in general there did not seem to
be any special reason why the fruit of certain canes should wilt
and in other cases not. This, with the fact that the wilting
or drying up of the berries started on certain ones of a bunch
before it did on others, and a single berry might be dried up on
one side while perfectly green and healthy on the other side,
suggested that possibly the trouble was not due to a wilting
caused by the fungus at work at the base of the canes, but rather
was a dry rot due to direct infection of the berries by this
fungus. This same idea had been suggested some years before
to the writer by a grower whose berries had been thus dried
up, but our imperfect examination at that time showed nothing
Jo support the belief. This time, however, it was proved to be
correct by a microscopic examination of the diseased and
XOTES ON FUNGOUS DISEASES FOR I906. 323
healthy tissues. In the healthy green tissues no sign of the
mycelium of the fungus was found, but in the adjacent dis-
eased tissues it was present more or less prominently. In the
berries, for instance, it formed slightly tinted branched threads
that worked their way into and between the cells of the fleshy
parts of the drupelets, but not into the stony tissue or the
embryo. When first infecting the berries, the fungus caused
the normal green color to become slightly tinted, as if ripening
prematurely; then the tissues gradually' turned brown and
dried up from the dry rot, which under favorable conditions
of moisture advanced through the whole berry, into its recep-
tacle and the calyx, and finally even down into its pedicel, kill-
ing the tissues as it advanced. The illustration given in Plate
XVIII, a, shows the upper three berries perfectly healthy while
those in the low^er row are entirely rotted by the fungus except
in the center berry, where the fungus had passed down the
pedicel only halfway, the lower half being still alive and green,
as shown by the lighter color. When going down the pedicels
and peduncle, the mycelium penetrates through the paren-
chyma cells of the bark, kills the young cambium cells, and
is also found in the cells of the pith. Just how far down the
cells of the stem the mycelium may pass was not noted by
later examination of the canes. Certainly it often goes far
enough to wilt other berries in the bunch that may have
escaped direct inoculation, though in this particular case most
of the berries seemed to have been inoculated directly.
While the fungus was not found in fruiting condition on
the berries, the search was not continued later than June.
Neither did specimens brought into the laboratory and kept for
a short time in a moist chamber develop the fruiting stage on
the diseased berries, but in one case where a bunch was kept in
water for some time, the fungus did finally fruit on the com-
mon peduncle. There was no other suspicious fungus in Mr.
Eastman's patch, and while this one was not so common in
Its fruiting condition as seen later in other patches, it was quite
common nearby on wild plants along the roadside, whose fruit
was sufifering from a similar dry rot. There is no doubt in the
writer's mind that the infection took place through the flowers
and very young fruit, and that the spores were carried bv bees
324 CONNECTICUT EXPERIMENT STATION REPORT, I906.
or Other insects that had previously crawled over stems coated
with the spores.
This wilt seems to be most severe on the blackcap varieties.
Among those complained of are the Parmer, Cumberland and
Kansas. To a less extent it has injured the red varieties. As
stated above, it was also found on wild black raspberries and a
few bundles of wild blackberries were seen that possibly may
have been suffering from the same trouble. When once the
fungus becomes established in a patch, it is apt to give trouble
thereafter, and in some instances it has eventually ruined the
patch. The few spraying experiments that have been tried
have not been very effective. Possibly if the spraying was
kept up for two or three years, better results might be expected.
It is quite difficult to make Bordeaux mixture stick to the new
canes, and this may possibly partially explain the failures. Of
course a thorough cutting out of the dead and diseased canes
soon after the fruiting season and again in early spring is
desirable. It might be well, too, to destroy any wild raspberries
in the immediate neighborhood.
TOBACCO, Nicoiiiana Tabacum.
Bed Rot, Corticium vagum var. Solani Burt. A special
study of tobacco diseases the past year has brought to light sev-
eral fungous troubles that have not been reported before in this
state. The Rhizoctonia stage of the above fungus, which is
so common on potatoes, has recently been reported by Selby in
Ohio as the cause of a bed rot of tobacco. He attributed to it
a dampening off of the young plants, and cankered areas on
the stems of the larger ones. This trouble is so similar to the
one mentioned in our last Report and attributed to a Sclerotinia
fungus that we afterward questioned whether it might not be
the same. Our much wider examination of tobacco beds the
past year, however, seems to show that the Sclerotinia fungus is
the common dampening off agent in the tobacco seed beds in
this state. We did, however, find the Rhizoctonia fungus
present in some of the beds, but so far as observed, its injury
was slight, and was confined, as with the potato, to the under-
ground parts. This does not mean that it may not be as serious
a pest here as in Ohio, but so far we have not been able to prove
NOTES ON FUNGOUS DISEASES FOR I906. 325
definitely that it was the cause of any serious injury. Since
it is so well known as a troublesome soil fungus on various
plants, there seems to be no reason why it should not be
responsible for some of our tobacco seed bed troubles. That it
is the same fungus that occurs on potato was shown where
some tobacco plants were left in the beds until about the middle
of July, since on tliese the Corticium or fruiting stage of the
fungus formed a white mealy coating at their base just as it
does on the potato stems. According to Selby, this fungus is
likely to develop most abundantly in an acid soil, so the applica-
tion of lime to such soils may prove in part a remedial meas-
ure. The general treatment for its prevention is the same as
that described later under the Stem Rot trouble.
Canker, A Bacterial Disease? Plate XIX, a, b. After
tobacco has attained considerable size in the field, say from July
on, occasional plants are sometimes found that have the stem
girdled underground or a cankered area reaching up a con-
siderable distance on the stem, as shown in the illustrations.
In time the bark of the diseased area underground may entirely
rot off, and yet the plant above may show the trouble only by
a slight dwarfing and a sickly yellowish color of some of the
leaves. The canker, when reaching above ground, shows a
dark brown sunken area in the bark sharply marked ofif from
its healthy green tissue. This trouble has been known by the
growers in this state for a long time, but as it occurs only
on an occasional plant, nothing has ever been published con-
cerning it. In our study of the root rot trouble mentioned
later, these cankers were noticed, but were believed to be merely
an extended injury of the root rot, as in the first specimens
examined that fungus was at work on the roots and also some-
what on the underground girdled area. Later experience, how-
ever, indicated that this fungus never produces the cankered
areas on the stem above ground, at least it was never found
there in a fruiting condition. In these places, however, there
was a more or less prominent development of bacteria, and
while no special study has been made with them, it seems
probable that they are the direct agents in extending these
cankers. No doubt root rot, stem rot, and even insect injuries,
may be the starting point of these cankers. Delacroix of
326 CONNECTICUT EXPERIMENT STATION REPORT, I906.
France has recently described (Recherches sur Quelques Mala-
dies du Tabac en France) a canker trouble of tobacco stems
caused by bacteria that possibly may be the same as this.
Dampening off, Pythium sp. Plate XXI, b. This fungus
was not found in the regular tobacco beds of the state, though
probably it does more or less injury in them, but it occurred on
some tobacco seedlings grown in the Experiment Station green-
house in rich loam. Though quite a different fungus, it
dampens off the young plants in much the same way as the
stem rot fungus described later, but can generally be told from
that trouble by the absence of any white fungous threads creep-
ing over the decayed plants. This fungus (probably Pythium
DeBaryanum Hesse) is a common dampening off agent of
3'Oung plants in greenhouses and hotbeds, especially if the soil
has been used for some time and contains an abundance of
organic matter and moisture. It can be prevented by the same
means employed against the stem rot trouble.
Root Rot, Thielavia hasicola (B. & Br.) Zopf. Plates
XXIX and XXXI. This was a trouble that was very pro-
nounced in certain tobacco seed beds and fields in the Connecti-
cut valley the past year. While probably not an entirely new
disease here, it certainly has not previously attracted the atten-
tion it did this year, and has never before been reported by
this Station. The injury occurs on the roots, which are often
rotted off the young plants. In this respect it differs entirely
from the dampening off troubles that rot the stem above the
ground. The disease is discussed in detail in a special article
in this report, so no further mention need be made of it here.
Stem Rot, Sclerotinia sp. Plates XX, a-b, XXI, a. This
is the fungus mentioned in our last Report as a "Dampening
Off" trouble of tobacco, but as the Pythium fungus described
above usually goes by that name, and has now been found here,
its name is changed to the Stem Rot trouble. So far as
observed, this is the common trouble with tobacco seedlings
in Connecticut. Its injury is quite similar to that described
by Selby for the bed rot caused by the Rhizoctonia fungus, and
both have very similar sterile mycelial threads. Artificial cul-
tures of the stem rot fungus, however, give rise to a pure white
mycelium which forms numerous small black sclerotial bodies
NOTES ON FUNGOUS DISEASES FOR I906. 327
that are similar to those of the drop fungus (Sclerotinia
Libertiana) of lettuce, and apparently quite distinct from the
artificial cultures of the Rhizoctonia fungus. Cultures made
from diseased plants obtained from the same place in Bridge-
water, Conn., both in 1905 and 1906, gave the same fungus,
which we have called provisionally Sclerotinia sp. In pass-
ing, it might be well to note that Delacroix of France has
described a Sclerotinia trouble of tobacco which occurs on the
mature plants. Our fungus usually appears in spots in the bed,
dampening off all the plants for some distance when they are
crowded and the moisture is abundant. Its white threads,
visible to the naked eye, form a slight cobweb-like coating on
the soil and the base of the plants. When the plants are quite
young, the stems just above ground are injured by a wet rot,
which causes the plants to fall over, and eventually they are
entirely destroyed. Plate XX, a, shows a specimen where the
base of the stem just above ground was rotted, while the stem
above and the roots below were uninjured. Sometimes the
plants are so far advanced that the tissues of the stem resist
the attack, with the result that only cankered spots are rotted
in the bark, as shown in Plate XX, b, and these may heal over
without further injury from the fungus. Such plants are
sometimes transplanted by accident in the fields, but they do
not usually make a satisfactory development, as they are often
broken off at these cankered places, which also offer entrance
for other agents of decay.
The stem rot, like other seed bed troubles, is likely to develop
in beds in which the plants are too crowded, or kept too moist,
either by excessive watering or lack of proper ventilation.
Care in these respects, therefore, will often prevent or stop the
trouble after it is started, but of course wet, cold springs often
make proper regulation of the moisture difficult. When the
trouble has been bad in beds for a year or two, it is likely to
cause more or less injury each season, and it is then desirable
to either change the beds or the soil in them. Beds made in
low, wet spots, or which contain abundant organic matter, are
likely to be most injured by this trouble.
The writer made a couple of experiments with spraying
diseased beds with weak formalin (i to 1500) to see how this
328 CONNECTICUT EXPERIMENT STATION REPORT, I906.
would work in keeping down further injury from the fungus.
Part of a bed at New Mil ford which was sprinkled twice
apparently did not show any improvement over the rest of the
bed. In another bed at Bridgewater, part of which was
sprinkled three times in June, aftet the fungus had caused con-
siderable injury, there was apparently some benefit from the
treatment. The writer did not see plants from this bed until
after they were pulled up, but the owner and his men said that
in the treated part the plants rotted less, cankered spots healed
over quicker, and the fungus developed less prominently than
in the untreated part of the bed. In certain beds at Hockanum,
which had been sprinkled several times for the root rot trouble,
the owner thought that the treatment had been a benefit. So
far as the root rot was concerned, the writer saw nothing to
indicate that the treatment had been helpful, but was inclined
to believe that possibly som-e benefit had been derived from
lessening the dampening off of the plants. While we cannot
state positively from these experiments and observations that
sprinkling the beds with weak formalin is valuable in prevent-
ing stem rot and similar troubles, it seems well worth a trial
in cases where the beds need to be watered more or less. In
such cases we would advise the use of weak formalin (the
standard 40 per cent, formalin, diluted with water at the rate
of I to 1500) entirely in the place of water. Such a strength
does not seem to injure the tobacco seedlings, and the exposed
fungous threads certainly would not develop in this as they
would in ordinary water.
Another method of preventing this trouble, when one does
not wish to change his bed, is by sterilizing the soil. This may
be done either by steam or formalin. The efifect of the for-
malin treatment is shown in Plate XXI, a. In box i the soil
before sowing the seed was thoroughly soaked with a strength
of formalin at the rate of i to 100 of water; in box 2 the
formalin was half as strong, i to 200; and in box 3 the soil
was merely soaked with water. These boxes were covered for
a day to keep the fumes of the formalin in the soil, and then
they were uncovered, aired, and the soil stirred to allow the
escape of the formalin. About a week after treatment they
were seeded similarly with tobacco. The boxes were covered
NOTES ON FUNGOUS DISEASES FOR I906. 329
part of the time with glass, which kept the air saturated with
moisture, and as the plants came up very thickly, the conditions
were excellent for the development of dampening off troubles,
except where the fungus had been entirely killed in the soil.
At first the two treated boxes were much better than the
untreated, showing no dampening off, though the plants were
crowded, while the dampening off soon developed in several
spots in the untreated box. Finally, however, one dampening
off spot appeared in box 2, (the weaker treatment, which appar-
ently had not been quite strong enough to entirely kill the
fungus), and because of the very crowded condition of the
plants at this time, rapidly spread through the box, and even
in time passed, at one corner between the glass partition and
the wooden side, into the box treated with the stronger solution.
The illustration shows the condition of the three sets of plants
about four weeks after seeding.
This experiment shows that the dampening off fungi evi-
dently can be largely killed in the soil if the formalin is strong
enough and the soaking of the soil is thorough. Based on the
results of this experiment, two infected beds were treated late
last fall at Bridgewater. In these cases formalin was used at
the rate of i to 100 of water, and the beds were thoroughly
soaked by gradually sprinkling on them a gallon per square
foot. The beds were then covered with gunny sacks over night
to keep in the fumes. Of course the results of these treat-
ments cannot be determined until later in the season.
TOMATO, Lycopersicum esculentum.
Black Mold, Fumago vagans Pers. Plate XVIII, b. We
have reported this fungus before on pears and apples, follow-
ing attacks of plant lice, and also on the linden. During the
past year it occurred at the Experiment Station on tomatoes
and nasturtiums in the greenhouse and on tobacco outdoors,
in each case following an attack of tlie white fly. On these
various hosts the microscopic characters of the fungus were
not always the same, as the Cladosporium may or may not be
associated with an Alternaria stage, or there may be more or
less of a Torula-like growth. For convenience' we have called
all of the specimens Fumago vagans, since this is the species
33° CONNECTICUT EXPERIMENT STATION REPORT, I906.
credited with growing in the honey dew of insects. The most
striking development of the fungus this year was on tomatoes
grown during the winter in the greenhouse. The white fly
confined its attack to the underside of the leaves, while the
black mold developed only on the upper side, where it formed
a conspicuous olive-black growth, as shown in the illustration.
From casual observation one would have supposed that the
fungus was really an active parasite developing on the tomato,
quite similar to the injurious scab fungus, which often appears
on the under surface of the leaves. The black mold in reality
did not grow as a parasite, but as a saprophyte in the honey
dew secreted by the fly. This honey dew evidently drops on
the upper surface of the leaves from the insects on the under
surface of the leaves above. This was shown in the case of a
tobacco leaf where the leaf had been partly folded on itself,
exposing its lower surface above. Here the black mold devel-
oped on the exposed lower surface, and on the upper surface
except where covered by the fold. It is doubtful if the fungus
itself does any injury to the leaf other than shutting ofif the sun-
light, but it does cause an unsightly appearance. There is a
possibility, however, that such a fungus, after continued growth
on a host in this manner, might become parasitic.
TURNIP, Brassica Rapa.
White Spot, Cercosporella alho-maculans (E. & E.) Sacc.
This fungus forms subcircular, greyish spots, showing on both
surfaces of the leaves, and varying from an eighth to a quarter
of an inch in diameter. When abundant on the leaf it causes
premature yellowing and death. The disease was observed
last September at Kent in a field of turnips, following tobacco,
where it was doing some damage. There is some question
whether or not this fungus is distinct from Cercospora
Bloxami B. & Br., and in general appearance it also resembles
the leaf spot trouble of horseradish caused by a species of
Cercospora.
VETCH, RUSSIAN, Vicia villosa.
Leaf Spot, Ascochyta Viciae Lib. Plate XXII, a. As the
Russian vetch has recently been highly recommended as a
winter cover crop for tobacco fields in this state, any fungus
attacking it becomes of some economic importance. In one
NOTES ON FUNGOUS DISEASES FOR I906. 33 1
field at Suffield, in October of the past year, some plants of
this vetch were observed that were being injured by the above
leaf spot fungus. This fungus forms subcircular, greyish
spots, with a prominent purplish border. The fruiting recep-
tacles are visible as minute black bodies bedded in the center
of the spots, as shown in the illustration. As the leaflets are
small only one or two spots generally appear on each, but these
are often sufficient to cause their premature death. The fungus
has been reported before in this country by Ellis, on the pods
of this same host, and also from Canada, on the leaves of a
different species of vetch. Saccardo lists Ascochyta Pisi,
a common fungus of the pea, on the Russian vetch, and as
this fungus is very similar to the species reported here, there
may be some question as to their distinctness.
VIOLET, Viola sps.
Speck Anthracnose, Marsonia Violae (Pass.) Sacc, Plate
XXII, b. We have previously reported a number of leaf dis-
eases of greenhouse violets. The above is one that has rarely
been reported in the United States. It v/as sent from Niantic
last fall by Miss Angle M. Ryon, who reported considerable
injury to various species of native violets which she was cul-
tivating for scientific purposes. The trouble differs chiefly
from the other leaf troubles of violets so far reported in the
very small size of the reddish spots, which are usually smaller
than a pin head. The spots, however, may become very abun-
dant, being scattered or clustered, and cause a yellowing of the
intervening tissues and serious injury to the leaves.
332 CONNECTICUT EXPERIMENT STATION REPORT, I906.
II. EXPERIMENTS TO PREVENT ONlON BRITTLE.
Nature of injury. In our last Report we described a peculiar
disease of onions, called brittle, that was reported by Burton
W. Bishop of Guilford as being- a serious trouble in that vicinity
when once it became established in a field. Our investigations
at that time indicated that the trouble was caused by a soil
fungus that worked especially in the roots but whose identity
was not fully established. The past season we made some
successful experiments to prevent this trouble but gained
little further information concerning its cause, partly because
of its obscurity but chiefly because this side of the investigation
was not especially considered. The general character of the
disease is briefly given in the following paragraph, but a
somewhat fuller account may be found on pages 270-3 of the
Experiment Station Report for 1905.
The trouble usually starts in some small section of a field
and each year extends out further, so that the land eventually
becomes of little value for growing onions. Weeds in the
infected area also do poorly. In some respects the trouble
resembles an acid soil, and yet this could hardly explain the
spreading of the trouble or the benefit that resulted from the
use of certain soil fungicides. While apparently caused by
a fungus, this is never evident externally on the roots and often
it does not seem abundant enough within their tissues to
cause so prominent an injury. Though not definitely deter-
mined by actual observation, apparently many of the very
young seedlings are dampened off or killed outright, since the
stand in the infected area is usually very poor and irregular.
In fact most of the injury seems to be to the seedlings, though
the older plants do not entirely recover from the backset they
received. The infected plants are much smaller than the
healthy ones near them or those in the part of the field free
from the disease, as is shown in Plate XXIII, a. Another
peculiarity is the brittleness of the leaves, from which the
trouble takes its name. Very often the leaves are quite irreg-
ular or have peculiar spiral coils as shown in h of this same
plate. The onions may also have a sickly yellowish green
color, especially in spots, instead of the normal dark green.
EXPERIMENTS TO PREVENT ONION BRITTLE. 333
PREVENTIVE EXPERIMENTS.
Nature of experiments. Through the courtesy of Mr.
Bishop, one end of his field was used in 1906 for experiments
in preventing the onion brittle. The disease showed first in
this field two years before and when seen by the writer in 1905
had infected an irregular area in one corner about two or
three rods each way. In 1906 this infected spot had greatly
extended itself, in one direction spreading nearly across the
field, though tapering out toward the further end. The
character of the infected area is shown in Plate XXIV, a,
which slightly exaggerates the injury to the onions in 1906
since some plants did come up on the vacant place, but these
were so few and scattered that they were finally plowed up as
worthless.
As the trouble is in tlie soil and injures the plants chiefly
while young, the treatments were made v^^ith this in view. In
the comer of the field where the trouble first showed, the
ends of one to seven rows (each 53 feet long and 14 inches
apart and so representing about one seven-hundredths of an
acre) were used for each treatment. The first set of treat-
ments, made at the time of seeding, April 20, was as follows :
Plot. No. Rows. Treatment.
1 6 (.1-6)...
2 4(7-10)..
3 I (11) ■••
4 7(12-18).
5 7(19-25).
Check ; no treatment.
Formalin (i to 240 water) at rate of 525 gals, per acre.
Limoid at rate of 700 lbs. per acre.
Sulphur and limoid (2 to i) at rate 200 lbs. per acre.
Complete fertilizer (i sol. bone black, i mur. pot., 2;^
sod. nitr.) at rate of 650 lbs. per acre.
6 00 (26-00). . Check ; no treatment.
In each case after the seed was sown the fungicide was
sprinkled or scattered over it and the adjacent earth before
covering. In this way the rates used were much more effective
than if the fungicides were scattered broadcast. The fertilizer
was scattered directly over the rows after the seed was covered.
This complete fertilizer was used partly to determine if the
land was lacking in fertility but chiefly to see if, with quickly
available food, the young plants could be forced to a rapid
development and so outgrow or escape the injurious action of
the fungus which seems to attack the plants most injuriously
while quite small. The land, however, had already been well
fertilized, since Mr. Bishop used at about the rate of 9 tons
334 CONNECTICUT EXPERIMENT STATION REPORT, I906.
of salt hay, Yz ton fish scrap and 3 tons wood ashes per acre.-
He used the salt hay, partly composed of sea weed, to get
more humus in the soil and because he thought that the salt
might have some influence in checking the brittle.
On June 9th, after the plants had made considerable growth,
a second set of experiments (similar lengths of two rows in
each case) was made to determine if the treatments would
have any effect in stopping or lessening the trouble after
it once showed in the plants. These treatments were with
limoid (700 lbs. per acre), ground fresh lime (700 lbs. per
acre), air slaked lime (700 lbs. per acre), fresh lime slaked
in water (^^ lb. to 2 gals, water used at rate 1400 gals, per
acre), and formalin (i to 1500 water in two applications at
rate each of 1400 gals, per acre). These rows all showed at
this time considerable injury from the brittle, especially in the
poor stand.
Results of experiments. The onions in the second set of
experiments (those treated after the plants showed the disease)
in no case at any time showed any very appreciable benefit from
the treatments. This indicates that the injury to the onions is
caused primarily while they are quite small, or at least that
this is the time of infection, and so any treatment to be effective
must be made at the time of seeding.
In the first set of treatments, made at the time of seeding,
the effect was quite evident soon after the plants appeared
above ground. The first examination by the writer, made on
June 4, showed that the stand and size of the plants were much
better in all of the plots treated with formalin, limoid, sulphur
and limoid than in the untreated plots and were practically the
same as the plants in the best parts of the uninfected portion
of the field. The weeds, too, which had been left for obser-
vation, were much more numerous and thrifty in these treated
plots than in the untreated. The relative size of the diseased
and healthy plants at this time is shown in Plate XXIII, a. The
plot on which the complete fertilizer had been placed was not
any better than the worst of the infected rows that had not
been treated at all. This showed plainly that the trouble was
in no way due to an impoverished soil or that the young plants
could be stimulated in growth to escape the trouble. Of the
check plots. No. i, which was on the very edge of the field,
was much better than No. 6, which made such a poor stand
EXPERIMENTS TO PREVENT ONION BRITTLE. 335
that the onions were worthless. Check plot No. i, however,
was not as good as any of the treated rows, but was consider-
ably better than the plot with the complete fertilizer.
On July 12 the second examination was made and about the
same relative condition of the plots was found. The striking
difference between the treated plots (limoid, sulphur and limoid,
and formalin) and the untreated plots (complete fertilizer and
check plot) is shown in Plate XXIV, b. This photograph shows
chiefly the sulphur and limoid and the complete fertilizer plots
and it brings out the sharp differentiation in size and number
of plants even in their two adjacent rows. A more detailed
view of the treated and untreated plants is given in Plate
XXV. In a is shown plants in the complete fertilizer plot
while in b, photographed at the same time and size, is shown
a row each in the sulphur and limoidj, limoids, and formalin2
plots.
The crop was harvested on Sept. 7, when the number and
weight of the onions in each plot was determined. As a whole
the season was very unfavorable for onions, so that the differ-
ence in yield due to the treatment, possibly, was not so great
as it would have been in a more favorable season. The treated
plots gave practically the same yield as the uninfected part of
the field. Mr. Bishop considers 400 bushels per acre a good
yield for this field during a favorable season, but this year
only about half this was obtained. The following table gives
the details of the yields in the different plots.
Yield oj" A Terage per A it. per
Onions. row S3ft. acre.
Plot. Treatment. No. Lbs. No.
Check 920... 54>^--- I53--
Formalin 1161... bo)^ . . . 290..
Limoid 268... 15 268..
Sulphur and limoid. .. . 2072... 99^... 296..
Complete fertilizer (check) 35 . .
Lbs.
Bu.
. 9...
121. . .
. i5i..
205. . .
. 15...
202. . .
. I4i..
191...
. ^%..
15...
The complete fertilizer plot, X^o. 5, and the check plot. No. 6,
were both practically alike and so poor as to be worthless ; so
the yield from the single row given here probably represents
about an average for these and the worst part of the infected
field. It is readily seen from this table that the treatments
considerably increased the yield over the best of the untreated
rows and as the larger part of the infected area was similar to
plot 5 the increase in reality was very considerable.
336 CONNECTICUT EXPERIMENT STATION REPORT, I906.
III. DRY ROT FUNGUS,
Merulius lacrymans (Wulf.) Schum.
Timber-destroying fungi in general. Both parasitic and
saprophytic fungi cause injury to our commercial forest trees,
the former doing- damage to the living trees, and the latter
producing decay of their wood after they have died from vari-
ous causes. Apparently the financial loss caused by the latter
class is much greater than that of the former. Such fungous
injuries in this country have been studied extensively by von
Schrenk of the United States Department of Agriculture, who
has issued several bulletins dealing with special troubles of
certain kinds of timber trees and their lumber. Popular
articles upon fungous injuries to trees have also been written
from time to time by other American botanists. Most of the
injuries to trees by fungi are caused by certain species belong-
ing to a group known technically as the Hymenomycetes, of
which the toadstools and shelf fungi are familiar examples.
In the present article we discuss an injury, caused by one of
these fungi, to the timber after it had been placed in a building.
This dry rot, or house fungus, is peculiar in that it is what
might be called a domesticated fungus ; that is, it rarely, if
ever, causes rot of the trees in the forests.* Mention has been
made in this country of slight injuries caused by this fungus to
the woodwork of cellars, greenhouses, etc., where the moisture
had been favorable for its development, and short popular
articles concerning the fungus itself have been written by Mac-
Bride, Freeman and Atkinson ; but the writer has found no
extended notice of serious injury caused by it. Mr. A. B.
Seymour, in a recent letter, writes that some years ago he
examined the rafters of a noted old church in Boston, and found
them considerably injured by dry rot, which, however, was
then entirely inactive. He also wrote that he was informed
*Appel (Arb. K. Biol. Anst Land. Forstw. 5: 204-6. 1906) recently-
tried to infect seedlings of fir and pine, grown in pots in the greenhouse,
by introducing the mycelium through -wounds in the stems; and -while
he did obtain a growth of Merulius lacrymans this in no way seemed
to be parasitic on the trees.
DRY ROT FUNGUS. 337
that the house at Cambridge in which OHver Wendell Holmes
was born was so injured by dry rot that it could not be moved,
and so had to be torn down to make way for the Hemenway
Gymnasium. In Europe, however, where the literature relat-
ing to this fungus is more extensive, serious injury to buildings
has been reported a number of times. The specific case
described in this article is of injury to North Carolina pine in
the basement of a church, and was called to the writer's attention
the past summer by ex-Senator William J. Clark of Stony
Creek. The writer made several trips to Stony Creek to observe
the fungus and its injury, and is indebted to Mr. Clark for
information concerning its first appearance, etc.
INJURY BY DRY ROT FUNGUS TO W^OODWORK OF A CIIURCH.
General situation. The trouble was called to our attention
about the middle of June, the first examination being made the
29th of that month. This stone church was comparatively new,
and a corner of the basement had recently been partitioned off
for a Sunday school room. The entrance to this room and the
basement was from a tower vestibule above, that also led into
the main auditorium. The steps leading down to the Sunday
school room were enclosed in a narrow passageway. It was
under these steps, close to the entrance of the Sunday school
room, that the trouble was first noticed in an inconspicuous way,
some months previous to our visit, through the rotting of a
few of the boards. These boards had been replaced, and noth-
ing more was seen of the trouble until after the furnace fire
was discontinued in the spring. The walls of the Sunday
school room are formed on two sides by the stone foundations
of the church, and on the other two sides by a board partition
separating it from the remainder of the basement, which is used
as a furnace and fuel room. The Sunday school room was
plastered to the floor directly on the stone on two sides, and on
lath on the other two sides. The baseboard and wainscoting,
of North Carolina pine in natural finish, covered the plastering
to a height of three or four feet all around the room. The
back of the board partitions on the furnace side of the base-
ment was sealed tight by unpainted boards. The steps lead into
the Sunday school room at one corner ; beneath these is a small
24
33^ CONNECTICUT EXPERIMENT STATION REPORT, I906.
dark closet opening into this room, and nearby in the wooden
partition a pair of swinging doors leading into the furnace room.
It was in this corner (see Plate XXVI) under the steps (where
the trouble originally showed) and in the closet that the fungus
started with renewed vigor in the spring. At the time of our
visit, a month or two after the first signs of its renewed attack
were noticed, it had spread on one side along the wooden parti-
tion, past the swinging doors, for a distance of about fifteen
feet; but on the other side of the steps, along the stone wall,
only a very short distance. Only one or two small isolated
outbreaks were found elsewhere, showing on the furnace room
side on a sill that rested on the damp earth. Fortunately the
floor of the Sunday school was cement, for no doubt if wooden
the fungus would have found a very favorable condition for
its development beneath it. The furnace room had no floor,
but contained piles of old boards for fuel, and in a number of
cases where the boards rested directly on the damp ground,
there was a slight development of the fungus.
Conditions favoring development. In Europe there have
been cases where this trouble developed in buildings apparently
because the wood used in their construction was already
infected with the fungus. In the present instance however,
this does not appear to have been the case, for apparently the
fungus started from infected old boards in or under the steps,
and afterwards spread to the new lumber because of the very-
favorable conditions for its development. While this is called
the dry rot fungus, it really requires moisture for its develop-
ment, which was very thoroughly provided in the present
instance. During the winter, while the furnace was going, the
fungus gave no evidence of its development, if present between
the wainscoting and the plastering. After the ordinary damp
spring months came an unusually wet June, with very frequent
heavy rain storms. These, together with the situation of the
church on a rock close to the Sound, made the moisture very
evident in the basement. Then, too, the basement was cool,
and so tended to condense moisture from the saturated atmos-
phere on the woodwork. The leaders on this side of the
church did not carry the water away from the foundation, and
on the other side there was no eave trough. This made the
ground around the basement Sunday school room very wet
DRY ROT FUNGUS. 339
during the frequent rains. The effect of the abundant moisture
was shown by the warping of the wainscoting even where there
was no sign of the fungus at work. The fact that the plaster-
ing extended down to the floor under the wainscoting and that
the back was sealed up was also most favorable for the develop-
ment of the fungus along the wooden partition, since here was
an enclosure that prevented its damp atmosphere from readily
drying out during the dry weather. Lastly, the slight space
between the back of the wainscoting and the plastering fur-
nished a most admirable place for the rapid development of the
fungus along the wall.
Character of the fungous growth. The fungus consists of
three parts: (a) the mycelium, which penetrates into the tis-
sues of the wood, and causes its decay ; (b) sterile mycelial
strands that develop on the surface of the boards, on the
protected side, and serve as a means for rapidly spreading the
fungus from one point to another; and (c) the fruiting stage,
formed by a luxuriant development of fertile hyphae into
special bodies bearing the spores, or reproductive bodies, on
their surface. The mycelium consists of branched microscopic
threads that penetrate into the wood between and into the cells,
and, according to Hartig, dissolve out the coniferin and cellu-
lose of their walls, which causes the cells to become very fragile.
In fact, in time the wood may crack up into little areas as it
dries out, and eventually is easily crushed into a fine powder
between the fingers. The mycelial strands are usually in the
shape of a flat mat, with meshes of irregular size and shape
(see Plate XXVII, b). Where the fungus showed prominently
on the exterior of the woodwork, these flat strands thickly
covered the under side of the boards and even the plastering, as
shown in Plate XXVII, a. They have a greyish color, and a
growing margin of a whitish, fluffy texture, as shown on the
wall in the same illustration. In some cases, especially on the
ground, or where the conditions for growth were limited, the
sterile mycelium, instead of forming a mat, took the shape of
cords or strands, and these often grew for a considerable dis-
tance. Such strands, by creeping through obscure or inac-
cessible places, under the sills, etc., offer a very dangerous
means for spreading the fungus to other portions of the build-
ing. When the moisture conditions of the room became favor-
34° CONNECTICUT EXPERIMENT STATION REPORT, I906.
able during the very wet weather of June, the fungus began
to show its presence by emerging between the boards of the
wainscoting and around the woodwork of the closet and the
swinging door, and developing its fruiting stage. This out-
growth was quite conspicuous, and appeared very rapidly (see
Plate XXVI). The growth at first was a fluffy mat of the
white mycelium, which, after appearing in the cracks, spread
out on either side for an inch or two in width and for a much
longer distance along the crack. While these immature fruiting
mats when fresh were an inch thick, when dried out they
became quite thin and leathery. At first they were white, and
without folds ; but soon they began to turn a reddish brown,
due in part to the formation of the colored spores. Where they
had a chance to fully mature, their surface became sculptured
with irregular folds or corrugations, or sometimes with flat,
tooth-like projections, after the usual manner of the fructifica-
tion of the genus. Plate XXVIII shows at a some of the
immature fruiting bodies on a piece of the wainscoting, while
at h the mature fruiting bodies are shown.
Damage caused. The rapidity with which the fruiting stage
of the fungus developed during the favorable weather of June
is shown in Plate XXVI. The growth as shown in a had all
been scraped off a week or so before this photograph was taken,
while h shows the condition just twelve days after the first
photograph was made. The fungus was so prominent at this
time, and its injury so great, that the trustees of the church
decided to remove all the infected woodwork. Many of the
boards of the wainscoting were very badly rotted, while others
were so badly infected that it was only a question of time
before they would be in the same condition. There was danger,
too, of the fungus spreading to the remainder of the woodwork,
and even above into the church proper. European writers
mention cases where the fungus, starting in a wet basement,
has spread up into the second story even when that part of the
building was dry. The fungus can do this easily by means of
its long sterile strands, which also carry food and moisture for
its development. Often this moisture is given off, and wets
surrounding objects, as the plastering in the present case in
one place well up on the wall. On account of this characteris-
tic, the specific name lacrymans (weeping) has been given to
DRY ROT FUNGUS. 34 1
the fungus. The actual damage in the present case was per-
haps less than one hundred dollars, but there was also the
danger of possible future attacks, which might be even more
serious, especially if the fungus worked into the main part of
the church.
Preventive measures. At the suggestion of the writer, all
of the infected woodwork was cut out, and even the plastering
and laths were removed where the fungus showed. The lower
boards on the sealed side of the furnace room were also taken
off to allow a circulation of air between the partitions. All the
infected material was destroyed, and the basement was also
cleaned of all rubbish. The drainage was carried away from
the walls of the church to keep these from becoming damp.
On July 2 1st, after the diseased wood had been removed, the
writer thoroughly sprayed the ground, plastering, and boards
near where the fungus had been at work, using water contain-
ing two per cent, of formalin and two per cent, of carbolic acid.
This was done in order to kill any scattered spores or superfi-
cial mycelial strands that might have escaped notice. That this
spray was effective against exposed mycelia was shown by
spraying part of a badly infected board. This was then sawed
in two, and the sprayed and unsprayed pieces were placed for
some time in a moist chamber. The sprayed half never made
any growth of the fungus, except a slight development on the
cut end of the board from the deeply imbedded fungus threads.
On the unsprayed board, however, the fungus developed
abundantly.
The partition has not yet been replaced, being left out to
see if the fungus will develop any further. At this date
(March 15th, 1907) it has showed no signs of reappearing.
342 CONNECTICUT EXPERIMENT STATION REPORT, IC)o6.
IV. ROOT ROT OF TOBACCO,
Thielavia hasicola (B. & Br.) Zopf.
GENERAL CONSIDERATION OF THE TROUBLE.
Discovery of the trouble in Connecticut. During the past
season a serious root disease of tobacco has been prevalent in
certain seed beds and fields in this state. While probably not
an entirely new trouble, it certainly has not heretofore attracted
any special attention among tobacco growers. Neither has the
fungus [Thielavia hasicola (B. & Br.) Zopf] causing it been
previously reported on tobacco by the botanists of this station,
though Thaxter in 1891 found it causing serious injury to
violets. Mr. Shamel, of the United States Department of
Agriculture, who is cooperating with this station in a study
of the improvement of tobacco by selection and breeding, was
the first to report it on this plant in the state. In an interview
with Mr. Shamel printed in the Hartford Daily Courant of
May 28, 1906, attention was called to the serious injury
caused by the root rot in the tobacco beds of the Connecti-
cut valley. It was also stated in this article, apparently from
personal observations, that this disease had proved a very
serious pest in Cuba, and had spread to an alarming extent
all over the tobacco-growing districts of America. Mr. Shamel
strongly recommended sprinkling the seedlings, in seed beds
showing the trouble, with formalin. In view of this serious
report, which was partially copied in a number of papers over
the state, and because of its especial interest in the tobacco
industry, this station, through its director and botanist, made a
careful study of the diseased seed beds and the fields during the
remainder of the season. There is given here a complete report
of this investigation.*
History elsewhere. The fungus responsible for this trouble
was first described from England by Berkeley and Broome
in 1850. They reported it as a probable parasite on" the base
* A preliminary report (6) of the investigation was made by the
Director and the Botanist in Bulletin of Immediate Information, No. 4,
of this Station.
ROOT ROT OF TOBACCO. 343
of the stems of peas and another plant. Zopf, of Germany,
in 1876, however, was the first to give a complete account of
the different stages of the fungus. He found it injuring the
roots of a species of Senecio, and some years later also on
the roots of a number of leguminous plants. Thaxter was
the first to report the fungus from America, having found it,
as previously stated, on the roots of violets in this state.
Peglion was apparently the first to find the fungus injuring
tobacco. In 1897 he made a report of injury to the roots of
tobacco in the fields of Italy. He thought that the water-
clogged condition of the soil was in part responsible for the
serious injury done by the fungus. Selby, of the Ohio Experi-
ment Station, was the first to find the fungus on tobacco in
the United States, having seen diseased specimens from seed
beds as early as 1899.
Nature of the fungus. There seems to have been doubt in
the minds of some of the investigators as to the exact parasitic
nature of the fungus. In the first place it belongs in a family
of fungi that consists chiefly of saprophytic forms, having a
few weak parasites. The other two species that have been
placed under the genus Thielavia are both saprophytes, one
having been found on dung and the other on dead stems of
Carduus. The fact that the fungus occurs on the roots also
tends to obscure its true nature and apparently at times to
induce a saprophytic existence.
Berkeley (2) said of the fungus: "It is either destructive
of the plant on which it grows or is developed on it in conse-
quence of previous disease." Zopf (24) considered it a true
parasite producing characteristic injuries to the roots, which he
called "Wurzelbraune." Sorauer (17) concluded that it led
a saprophytic as well as a parasitic existence, as he found it
developing on certain leafmolds, and he also stated that it might
occur in the soil at times without doing injury to the roots of
plants grown there. Peglion (9), as we have already stated,
thought that unfavorable conditions for root development, a
water-clogged condition of the soil, influenced its attack on the
field tobacco in Italy. Selby (13) while noting that the fungus
caused evident injury in the seed beds, stated that "the field
development of the trouble remains open for study with us."
Aderhold (i), who made some infection experiments, failed
344 CONNECTICUT EXPERIMENT STATION REPORT, I906.
to infect Begonia semperflorens, though his cultures originally
were obtained from a diseased Begonia, but he did succeed with
several other species. He was able in these cases, however, to
produce the disease only at the crown of the plants. This
seems peculiar since with tobacco it is the rootlets that were
found most injured. It is quite probable, however, that if
infection experiments were carried on with seedlings that the
roots would be readily infected. Aderhold agrees with
Sorauer that the fungus becomes an aggressive parasite only
under certain favorable conditions. Shamel (15) evidently
considered it a very injurious and aggressive parasite.
In Connecticut some of the growers were inclined to regard
the fungus as only an incidental, or at least a secondary, factor'
in the root rot of the tobacco, especially of that in the fields.
After an extended study of the subject the writer has no doubt
of the parasitic nature of the fungus under certain conditions
and believes that it was directly responsible for the serious
injury in the seed beds this year. Whether or not the very
conspicuous trouble in certain of the tobacco fields of Suffield
was primarily and chiefly due to it is not so easily settled in
our mind, though there is no doubt that it was at least partly
responsible. In any case the development of the fungus and
the consequent injury to its hosts depends largely on certain
environmental conditions (nature of soil, moisture, etc.) which
will be discussed later.
Hosts and distribution. In order to determine how common
this fungus is and how large a number of plants it has for
hosts, the writer made a rather careful examination of the litera-
ture of the subject and also sent inquiries to a number of men
who would be most likely to know of its presence in the various
-tobacco districts in the United States, Cuba and Porto Rico.
As a result of this search no one was found who had observed
the fungus (based on microscopic examination) on tobacco
plants in Cuba, Porto Rico, Kentucky, North Carolina, South
Carolina, West Virginia, Pennsylvania, Tennessee, Florida,
Texas or Wisconsin. This does not mean necessarily that the
disease does not exist in any of those states but simply that no
reliable information is yet at hand for stating positively that it
does. So far, then, the fungus has been found on tobacco
only in Italy, Ohio and Connecticut, but we have reason to
ROOT ROT OF TOBACCO. 345
believe that it also occurs in Massachusetts and possibly in
South Carolina. If it occurs in Cuba, the experiment station
there, at least, is entirely ignorant of its presence.
All of the hosts and localities, with the authorities for the
same, so far noted, are as follows : Aralia quin que folia', Gin-
seng, Ohio (Selby) ; Begonia rubra, Ohio (Selby) ; Begonia
sp., Germany (Aderhold) ; Cochlearia Armoracia, horseradish,
Kazan, Russia (Sorokin) ; Cyclamen sp., Germany (Sorauer) ;
Lupiniis albus, Halle, Germany (Zopf) ; Lupinus angusti-
folius, Halle, Germany (Zopf) ; Lupinus luteiis, Halle, Ger-
many (Zopf) ; Lupinus thermis, Halle, Germany (Zopf) ;
Nemophila auriculata, King's Clifife, England (Berkeley &
Broome) ; Nicotiana Tahacum, tobacco, Italy (Peglion, Cap-
pelluti- Alto mare), Ohio (Selby), Conn. (Shamel, Clinton) ;
Onohrychis Crista-galli, Halle, Germany (Zopf) ; Pisum sati-
vum, pea. King's Cliffe, England (Berkeley & Broome), Halle,
Germany (Zopf), Gembloux, Belgium (Marchal) ; Senecio
elegans, Berlin, Germany (Zopf) ; Trigonella caerulea, Halle,
Germany (Zopf) ; Viola odorata. Conn. (Thaxter).
Besides the above host Aderhold, by means of artificial
inoculations, infected Scorzonera hispanica, Dauciis Carota,
Beta vulgaris and Apium graveolens slightly and Phaseolus
vulgaris more prominently. There is also some indication that
the fungus attacks somewhat some of the weeds in the tobacco
beds in Connecticut. These references show that the fungus
has a wide range of hosts, which are widely scattered among
the different families of flowering plants, but that, so far as
reported, those of the leguminose family are most generally
attacked.
Structure of the fungus. The mycelium or vegetative part
of the fungus consists of hyaline, septate, branched threads
that penetrate into the tissues of the root eventually causing
their death. The mycelial threads are of rather narrow diame-
ter, chiefly 3 or 4'^/ and their branches are usually formed
near the apex of a cell, the branch being cut off by a septum
at its base, as shown in Fig. 14, a. The mycelium developed
externally on the hosts soon becomes slightly tinted and even-
tually gives rise to three kinds of spores, or reproductive
bodies. Zopf (22) in his original article described a fourth
kind of spores (stylospores or spermatia in pyenidia), but as
346 CONlSfECTICUT EXPERIMENT STATION REPORT, I906.
he did not mention these in his later article, and as others have
not described them, it may be that he was mistaken about their
being connected with this fungus. The writer, at least, has
not seen them, but all of the other kinds were found on the
diseased tobacco roots.
The first kind of spores formed are called endospores, Fig.
14, c, because they are formed inside a special thread of the
mycelium. This special endospore case is formed terminally on
Fig. 14. a, mycelium (a\ fertile); b, endosporous threads; c, endo-
spores (c\ germinating) ; d, chlamydospores (d^ fragmenting, d^,
germinating) ; e, ascospores.
the thread or on terminal, somewhat clustered branches. It has
a slightly swollen base, usually with several short basal cells, and
a long tapering terminal cell. The endospores are gradually
formed in the apex of this terminal cell in a basipetal manner
and are pushed out of the ruptured end by the growth of the
unfragmented protoplasm of the base. Usually these fertile
threads are slightly tinted but have very thin walls, so that it is
ROOT ROT OF TOBACCO. 347
often necessary to use the highest powers of the microscope to
determine that the spores originate internally in the thread and
not by its direct septation. Often one, can see endospores
slightly protruding beyond the case and in old specimens
examples are found where the case projects beyond the terminal
endospores as shown in Fig. 14. In nutrient cultures very
often these endospores remain attached in long strings after
being pushed out of the case. The endospores are hyalin, thin
walled, oblong to linear, and vary in size from 10 to 25 /x, in
length by 4 or 5/x, in width. They have a conspicuous nuclear-
like body in either end. Aderhold does not consider the endo-
spores as sporangial spores but rather as conidia.
The second kind of spores formed are the chlamydospores,
Fig. 14, d, which are thicker walled, dark reddish brown bodies.
They rarel)^ germinate soon after formation and so are in the
nature of resting spores and are adapted for carrying the fungus
over periods unfavorable for growth. They are borne on the
same mycelium as the endospores, often as side branches at the
base of an endospore thread. Some writers have considered
them as simple spores adhering in chains, but they are more prop-
erly considered as compound spores consisting of one or two,
rarely three, sterile basal cells and one to seven fertile cells.
The basal cells are hyaline or slightly tinted, while the fertile cells
are dark reddish brown, thicker walled and eventually separate
into pill-box shaped individual cells. As a whole the compound
spores are oblong with 'the terminal fertile cell rounded and
sterile basal cells tapering slightly toward the base. The length
of the spores, excluding the sterile base, varies from 20 to 50^
and their width from 10 to iSh-. While these spores are
usually formed on the mycelium externally on the root, they
are sometimes produced sparingly inside the cells of the root.
In this case they resemble the Torula fungus, hence Berkeley's
classification.
The third kind of spores are the ascospores, Fig. 14, e. These
are dark colored, single celled, lenticular spores about 12^ in
length by 5)11 in width. They are produced in asci, or hyaline
sacs, each ascus containing eight ascospores and in turn these
asci are enclosed in a special spherical receptacle called the peri-
thecium. While we have found these ascospores common on
the older tobacco roots, especially toward the end of the
34^ CONNECTICUT EXPERIMENT STATION REPORT, I906.
season, they were always shed out on the tissues, which indi-
cated that the asci and perithecia were either very fragile or
temporary. So far as our own observations go we could not
positively assert their relationship to the other spore forms of
the root rot fungus, but from their presence and the observa-
tions of others there seems to be no reason for doubting this
relationship. Though the fungus develops under ground it is
well provided with means for its propagation and dispersal
through these various spore forms.
Artificial cultiires. Aderhold was apparently the first to
make pure cultures of the fungus on various sterilized media.
The writer has also obtained cultures from diseased tobacco
roots. At first some difficulty was experienced in getting any
growth of the fungus, either because the spores did not ger-
minate or because this fungus was easily crowded out by
bacteria and other fungi. Finally, however, several isolated
colonies (possibly from endospores) appeared in a Petrie dish
separation culture of acid potato agar in which spores from a
freshly diseased tobacco root had been used. From these, pure
cultures in test tubes were easily obtained. The fungus grows
very readily on potato agar and soon produces an abundance of-
its endospores and later of the chlamydospores. It forms a
slight aerial growth that at first is greyish but with the produc-
tion of chlamydospores the cultures finally become quite dark
colored. So far the ascosporous stage has not appeared in the
cultures; but, as very often such stages do not appear in cul-
tures, this is no real proof that it is not a stage of the fungus as
declared by Zopf.
These artificial cultures give very favorable opportunity for
studying the fungus in detail and for determining points in its
life history not easily made out otherwise. For example, the
writer has only occasionally seen the endosporous stage on the
roots of tobacco and it might easily be entirely overlooked. In
the cultures, however, this stage is the first to appear and
produces the endospores in great abundance on the surface of
the agar, while the chlamydospores are produced chiefly
imbedded in the agar, to which it gives a blackish color in time.
The endospores germinate readily in drop cultures of potato
agar and manure-water but usually fail entirely to germinate
in pure water. The fungus also grows readily on sterilized
horse dung. These facts seem to indicate that the endospores
ROOT ROT OF TOBACCO. 349
are aerial spores and would develope abundantly in manure
piles, thus greatly facilitating the spread of the fungus. Sev-
eral writers have spoken of finding a whitish growth (appar-
ently an aerial growth of the endosporous stage) at the crown
of infected plants, but so far on tobacco we have seen no such
growth but have found chiefly the chlamydospores forming a
blackish growth occasionally at the crown but chiefly on the
roots or rootlets anywhere under ground. As the fungus is
still under investigation further details of its structure and life
history will not be given here.
Synononiy and relationships. As has been stated, Berkeley
and Broome first described this fungus, placing it under the
genus Torula because of the Torula-like character of the
chlamydospores, which were the only fruiting stage observed
by them. Zopf was the first to recognize the endosporous and
the ascosporous stages and because of the latter he placed it in
a new genus which he called Thielavia. This same year, 1876,
Sorokin (18), of Russia, found the chlamydospores on the
roots of horseradish and, thinking the fungus to be a new spe-
cies, called it Helminthosporium fragile. Sorauer (16), in
1886, apparently, was the first to recognize Sorokin's species to
be the same as Berkeley's, for this same year Saccardo (11)
ignored their identity by placing Sorokin's species under a
different genus, Clasterosporium. The correct name of the
fungus and its synonomy, so far as now known, is as follows :
THIELAVIA BASICOLA (B. & Br.) Zopf. Sitz. Bot. Ver.
Prov. Brandenb. 18; 101-5. Je. 1876.
Torula basicola B. & Br. Ann. Mag. Nat. Hist., II, 5: 461.
1850.
Helminthosporium fragile Sor. Hedw. 15: 113. Au.
1876.
Clasterosporium fragile Sacc. Sacc. Syll. Fung 4: 386.
1886.
Winter (21), Zopf (24) and Saccardo (10) all placed the
genus Thielavia under the family Perisporieae of the Peri-
sporiaceae (the latter also including the family Erysipheae, the
powdery mildews) ; but Fisher (4) did not consider the
genus at all related to the powdery mildews, as he placed it in
the family Aspergillaceae of the Plectascineae. All the writers,
35° CONNECTICUT EXPERIMENT STATION REPORT, I906.
however, consider Thielavia nearly related to the genera
Penicillium and Aspergillus, or the common blue molds. So
far only two other species of Thielavia have been reported and
in both of these only the ascosporous stage is described by
Saccardo. Thielaviopsis is a possibly related genus, though
no ascosporous stage is known, as one of its, conidial stages is
very similar to the endosporous stage of Thielavia hasicola.
DETAILED CONSIDERATION OF THE TROUBLE IN CONNECTICUT.
In the seed beds.
Difference between dampening off and root rot. For years
the tobacco seed beds of Connecticut have been injured more
or less by dampening off fungi. These dampening off troubles
however, are quite distinct from the root rot disease. With
the former, the stems of the young plants are attacked above
ground by certain fungi which, when soil and air are very
moist, may develop on the surface of the beds and on the base
of the plants as delicate, whitish, cobweb-like growths. These
filaments of the fungus penetrate into the tissues of the stem
and induce a soft rot of the tissues which causes the plants to
collapse and a further rot of the leaves takes place, especially
if in contact with the ground. Thus vacant spots appear in
the beds where all the plants have been rotted out; or, when
the trouble is not so bad the stand is thinned by the deatli of
a few individuals. Frequently a plant may be attacked, but,
through rapid growth or moisture conditions unfavorable for
the development of the fungus, escape injury further than a
cankered area on the stem. These dampening off troubles are
augmented by very damp and cloudy spring weather, and not
infrequently are started by lack of skill or care in watering or
ventilating the beds. As the fungi are capable of living in the
vegetable mold of the soil, they become established in the beds
and cause more or less injury each year.
Characteristics of root rot. The root rot fungus, on the
other hand, develops almost entirely underground, attacking the
roots and underground part of the stem. The tap root, which
is prominent in the young plants, is often rotted off close to
the stem or there may be a general rotting of the tap and
secondary roots, as shown in Plate XXIX. Not infrequently
ROOT ROT OF TOBACCO. 351
severely injured plants form new secondary roots further up
on the stem and under favorable conditions partly or entirely
outgrow the trouble. Sometimes the roots are only slightly
injured, having the secondary roots rotted off near their ends
or tliere are scattered diseased spots that may be finally out-
grown, as the fungus does not develop so readily on the larger
and harder roots. All of this injury, except rarely a cankered
spot on the base of the stem, is hidden from view until the plants
are pulled up. When this is done one is often surprised to
find how easily the plants separate from the soil, but an exami-
nation shows that there were few or no roots to hold the plants
to it.
The grower usually first notices the trouble by the plants
failing to make normal growth or coming entirely to a stand-
still. The leaves may show to his critical eye an unhealthy
dark green color which he often describes as "black." In time
there is a very uneven stand of the plants in the bed due to
some plants being more injured than others. Eventually there
may be a sickly yellowing of the older leaves. While some
of the plants are killed when quite young and others may be
carried off later, still it is very remarkable how many of the
plants continue to live even when most of their roots have been
rotted off. On a bright day this lack of root system becomes
evident through the premature wilting of the plants. Later in
the season the beds may show considerable improvement, since
the plants have had time to develop new roots and the warmer,
drier weather is more favorable for their outgrowing the
disease.
Extent of the trouble. In order to determine how general
the trouble was in the seed beds of the state, the writer, by
visits, personal inquiry and correspondence, attempted to locate
as many of the infested beds as possible. Such beds were seen
at Simsbury, Granby, Tariffville, Poquonock, Hockanum and
Portland. In all, however, the disease was definitely located in
the beds of less than twenty growers. Often only one of the
beds of the grower was seriously injured. No doubt this does
not show the complete distribution of the trouble, as some
growers are reticent about giving information concerning such
diseases. Others may have suffered but slightly from the
trouble and so it would easily escape their notice ; still others
352 CONNECTICUT EXPERIMENT STATION REPORT, I906.
may have suffered in ignorance of its real nature, as some
growers at first were inclined to lay the trouble to fertilizer
burn. All of these infected beds were in the Connecticut
valley, the chief tobacco region of the state. Although similar
effort was made to find the trouble in the smaller tobacco region
of the Housatonic valley, not a single case was found or even
heard of in this region.
Loss caused. The disease at its worst practically ruined
the beds, as few of the growers would risk planting from such
beds. This meant the loss of time, etc., in taking care of the
bed, often the purchase elsewhere of healthy plants and fre-
quently a delay in setting out the fields. One grower esti-
mated that this loss to him was equal to one hundred dollars.
In other cases growers, who set from beds that did not show
the trouble badly, became scared afterwards because the plants
did not start promptly, and they plowed these up and reset
with plants from uninfected beds.
Experiments tried, (i) Sprinkling seedlings. Mr. Shamel,
in the article in the Hartford Courant, was reported as strongly
recommending "that upon the first appearance of the pest the
remaining plants in the beds must be sterilized with a solution
of formaldehyde," of a strength of i to 2000 of water. He
recommended sprinkling the affected beds once a week with
the formalin, thoroughly soaking the plants and the soil. Mr.
Shamel based this recommendation on some beds he had
sprinkled with formalin where the treated plants afterward
seemed to make a better growth than those not sprinkled. In
view of this recommendation the writer had treated a part of a
bed badly infected with the root rot at Portland. This bed was
first treated June nth with formalin of a strength about i to
1500. A very thorough sprinkling was given the plants, using
at the rate of a gallon to each six square feet of the bed.
Altogether the plants were sprinkled with the formalin five
times, June nth, 13th, 15th, 19th and 25th. The plants were
finally examined July loth by the writer, and the treated plants
did not seem to be any better, more vigorous, or freer from root
rot than those side by side that were not treated ; neither had
the owner noticed at any time any indication of a better growth
in the treated part of the bed.
ROOT ROT OF TOBACCO. 353
We also had the opportunity to examine several beds at
Hockanum and Simsbury that were sprinkled two to several
times under Mr. Shamel's direction, but in no case were we
able j;o find any positive evidence that the sprinkling had been
of value in checking the root rot or hastening a healthy, growth
of the diseased plants ; and two out of the three growers who
had tried the experiment reported unfavorably for the treat-
ment. One of the growers, however, thought that the treat-
ment had been of benefit to his beds, but in this case, so far as
the writer could determine, this benefit, if any, was not in
preventing the root rot, but rather in lessening dampening off
of the plants, which is another disease altogether.
From the theoretical side this treatment does not seem to
promise much, since the formalin must be used in very weak
solution, so as not to injure the foliage or roots when sprinkled
on the plants. It is quite possible that this weak formalin might
act unfavorably on the very thin-walled endospores of the
fungus, but on the thick-walled chlamydospores, which are the
common spores on the roots, it is doubtful if such a weak
solution would have as injurious an action as it would on the
tender root hairs of the tobacco. Then, too, the mycelium of
the fungus on the diseased roots is largely within their tissues,
and certainly this would not be killed without killing the roots
themselves.
Taking all the evidence into consideration, we do not believe
that sprinkling beds already showing the disease will be of
value in lessening injury from root rot, and -we doubt if such
treatment will be of any considerable value even if it is begun
before the appearance of the rot. Now, in this statement, we
do not include the dampening off and stem rot troubles, since
in some of the beds having these troubles there did seem to be
some benefit derived from the treatment. In these cases, how-
ever, the sterile threads of the fungus creep exposed over the
surface of the ground and on the plants, and considerable
moisture is necessary for their development. If, then, in place
of the ordinary water, the weak formalin is used, while it might
not kill the fungus threads, it certainly would not be so favora-
ble for their further development. This phase of the subject is
discussed under the Stem Rot of Tobacco, page 327 of this
report.
25
354 CONNECTICUT EXPERIMENT STATION REPORT, I906.
(2) Sterilizing the soil. While the sprinkling method does
not appear to the writer to have much value, the use of stronger
formalin on the soil, as a disinfectant, before the beds are
seeded down did seem to be of value in killing out the root rot
fungus, and so exempting the seedlings from its attack. Selby
of Ohio has already obtained encouraging results against other
soil fungi by such treatment. To test this in a preliminary way,
soil from an infected bed was obtained and placed in boxes in the
greenhouse. On June 23d, the soil of box i was thoroughly
soaked with formalin of a strength of i to 100 of water ; the sec-
ond, with formalin of a strength of i to 200, and the third, or
check, merely soaked with a similar amount of water. After
covering for a day to keep in the fumes, the soil was stirred and
aired for a week to allow the formalin to escape. The boxes
were then seeded with tobacco, and afterward treated alike
"throughout the test. Root rot did not develop as badly in any of
these boxes as it had earlier in the seed bed from which the soil
was taken. It did appear in time somewhat prominently in the
untreated box. There was also some in the box treated with
the weaker strength (i to 200) of formalin, thus indicating that
this treatment was not quite strong enough for practical use.
In the box treated i to 100, while there was a very slight trace
of the rot, the treatment practically prevented it. -In neither
of the treated boxes did the formalin seem to retard germina-
tion, or injure the plants afterwards, but instead, these boxes
really gave a thicker stand of plants.
From the preceding experiment it seemed probable that
thorough treatment of an infected bed with formalin of the
strength of i to 100 might prove very useful in preventing
the root rot. Consequently part of a badly infected bed at
Portland was treated on July loth. A thorough soaking
was given, using a gallon to every i>^ square feet. The
treated part was covered with sash for a couple of days to
hold in the fumes, and then aired for about a week before seed-
ing it and the adjacent untreated strip, which was to constitute
the check. The illustration, Plate XXX, a, shows the condition
of the treated and untreated plots of this bed on September
5th. As is seen from this, plants in the treated part were
much larger, being large enough for setting out, and there was
a thicker and more uniform stand. There was no indication of
ROOT ROT OF TOBACCO. 355
disease to the naked eye. A microscopic examination of the
roots showed only traces of the root rot fungus. The untreated
plants, on the other hand, revealed some external signs of the
trouble, by the dwarfed, darker colored foliage, and an examina-
tion of the roots showed the fungus present on all of the plants,
in some cases rotting the roots badly. A later examination, on
September 24th, still showed the plants in the treated soil
superior to those in the untreated ; and the owner stated that
the difference in weeding the beds had been greatly in favor of
the treated part, which indicated that the treatment had been
strong enough to kill many of the weed seeds. The only thing
that prevents the conclusion that this evident difference between
the treated and untreated plants was entirely due to the treat-
ment is the fact that the untreated part of the bed was not
soaked down at the time of treatment with an equal amount of
water. It is barely possible that the thorough soaking the
treated part received was in itself a favorable condition for
better plants during the month of July. This month, however,
was rather moist, and after seeding the treated and untreated
parts were watered alike, apparently as often as needed. Any
great amount of water in the soil in the untreated part would
have been more favorable for the development of the root rot.
Because of this drier condition of the soil, and possibly because
of other seasonal conditions, as heat, the root rot was not so
bad in this bed as in the spring. Even the dwarfed plants had
a better root system, as shown by their not being so easily pulled
from the soil. There was no question, however, that the treat-
ment was at least partially responsible for the difference in the
condition of the plants.
Based on the above experiment, parts of two other seed
beds were treated in the fall to determine the ef^ciency
of this treatment. Another was treated this spring to deter-
mine the comparative value of spring and fall treatment.
In the fall treatments a very thorough soaking with formalin,
I to 100, using one gallon to each square foot, was given. It
is quite possible that this thorough soaking of the ground in
spring, when the soil is naturally moist, will not always allow
it to dry out sufficiently for the most favorable growth of the
plants, so only ^ of a gallon per square foot was used. The
results of these experiments cannot be reported until later.
356 CONNECTICUT EXPERIMENT STATION REPORT, I906.
Besides the sterilization of the soil with formalin, part of
a bed in one of the fall treatments was sterilized with steam
by means of a steam rake, whose teeth were forced into the
soil. Of course the comparative merits of this treatment and
the formalin treatment are not yet determined, but in so far as
cost and quickness of treatment are concerned, the formalin
method without question is far superior. As the result of our
various experiments and observations, later in this article, under
Preventive Measures, we recommend certain tentative treat-
ments for the prevention of the root rot.
In the fields.
Effect on the plants. Beside the backset early in the season,
which many plants entirely or largely outgrew, there were other
cases where the plants made no satisfactory growth the whole
season. Examination of the roots showed that the fungus had
continued its injurious action here during the season. Such
plants usually did not have the normal main and fibrous root
system shown in the healthy plant in Plate XXXI, b ; but the
main roots were more or less rotted off or easil}^ broken when
pulled up from the ground, and the development of the fibrous
roots and rootlets was very deficient (Plate XXXI, b) or abnor-
mally clustered at the crown. The fungus evidently can work
on the young rootlets and the small fibrous roots much easier
than on the larger and more woody secondary roots. While it
sometimes rotted off the larger roots, it more frequently showed
as an encircling banded blackish growth that was apparently
doing comparatively little injury. These blackish growths
(Plate XXXI, a), in the examination of the washed roots,
gave a very good idea of the abundance of the fungus and its
probable injury to the plant. So far as was learned, the fungus
did not attack any part of the plant above ground, though occa-
sionally plants with black sunken areas were found where the
trouble may have had its start from a root rot injury.
Extent of the trouble. In order to determine how general
the fungus was in the fields, the writer made a careful exami-
nation of forty-six different fields scattered over the state.
These were examined chiefly after the tobacco had been cut in
the fall. The roots of at least ten plants in different parts of
ROOT ROT OF TOBACCO. 357
each field were pulled up and washed and then examined for
the characteristic black spots of the fungus. These tests were
verified later by a microscopic examination. Twenty-eight of
these fields were in seven different towns in the tobacco region
of the Connecticut valley. In all of these fields, except two,
the fungus was present, at least to some extent on the roots,
thus showing it to be quite general in its distribution in this
valley. In two towns in the Housatonic valley eighteen fields
were examined, but the fungus was found only in eight of
these.
Damage done. In none of the fields in the Housatonic
valley was the fungus found in any abundance, and in most
of the eight cases only a trace of it was seen on a few of the
roots. Neither was there complaint by the growers of any
trouble that could at all be attributed to this fungus. So it can
be pretty safely stated that in this valley there was no injury
this season from the root rot. In at least eleven of the twenty-
eight fields in the Connecticut valley the fungus was found
abundant enough on the plants examined to have caused appre-
ciable injury. In all of these cases conversation with the
owners showed that the field as a whole or in spots had not
done as well as it should have done. In some cases it was
merely a small spot or portion of the field that did not give a
normal growth, and an examination of the roots from these
places always showed more serious injury by the fungus than
in the rest of the field. Serious damage to the fields as a
whole, however, was confined chiefly to the region of Sufifield,
and here the root rot was most abundant. In this town a num-
ber of the fields of some of the best tobacco growers did
unusually poorly in a year when the crop in general was
unusually good. In these fields the tobacco at harvest time was
smaller than it should have been and on certain areas made no
satisfactory growth through the season and so was practically
worthless. The tobacco from these poorest spots often failed
to cure down properly in the barns, some leaves still remaining
green late in October, when the main bulk of the crop in the
same barn was ready to come down. As some of the most
seriously injured fields were of considerable size, this short
crop meant a serious loss to the growers. According to one
'358 CONNECTICUT EXPERIMENT STATION REPORT, I906.
grower, at least, the quality of this tobacco was not seriously-
affected.
Secondary factors possibly determining the injury in the
fields. Some of the growers, especially with the seed bed
trouble, were inclined at first to look upon the injury as a
fertilizer burn. There seems to be little ground for this belief
as regards the seed beds. Whether or not the presence of more
or less of certain of the fertilizers used would stimulate or
retard the growth of the fungus is another question not so
easily answered. It is not definitely known whether an acid,
alkaline or a neutral soil is best adapted to the growth of the
fungus, which we know can grow in the soil itself apart from
the tobacco root, but it is reasonable to suppose that this factor
may have its influence. Neither can we state positively v/hether
or not certain methods of field fertilization (showing in an
excess or lack of certain fertilizer constituents this season)
had an injurious action on the development of the tobacco aside
from, and possibly in the worst fields greater than, the injury
that was evidently caused by the root rot fungus. One of the
growers whose fields suffered severely was inclined to lay it
to the excessive use year after year of potash fertilizers, which
gradually accumulated in the soil, and especially to the use of
the carbonate of potash. Possibly the use of infected manure
may have had a bearing, as this would be favorable for the
development of the fungus. No special evidence, however, was'
obtained along this last line unless it was in the case of one of
the seed beds.
A very prominent factor, undoubtedly, is moisture. One
grower stated that the worst infected fields in Suffield were
those that had been under tents a couple of years previously.
If this was generally true, it is possible that the more moist
condition of the soil when under the tents gave the fungus a
better chance to develop and infect those fields later. A very
moist soil seems to be most favorable for the development of
the fungus, as the lower or damper spots in the fields usually
showed the most trouble. The nature of the subsoil as regards
drainage also may have had its bearing, especially early in
the summer. The character of the past season no doubt Avas
also an important factor. The cold wet weather of early spring
helped along the trouble in the seed beds, particularly when
ROOT ROT OF TOBACCO. 359
they were not properly ventilated. The rainfall* in June and
July was considerably above the average, which was no doubt
favorable for the growth of the fungus in the fields and may
have had its bearing' on the fertilizer question.
Future injury? The questions arise, is this trouble likely
to occur as seriously in the worst fields another year, and will
it grow more injurious in time in the fields where it is at pres-
ent doing little or no damage? It is not possible to answer
these questions definitely, because of the other factors than the
mere presence of the fungus in the field that have an influence
in determining the injury done. Taking all of these factors
into consideration, and the fact that the trouble appeared so
suddenly and prominently this year when no doubt the fungus
must have been present in the soil, at .least inconspicuously, for
some time (as it now is in some parts of the Housatonic valley,
with no injury to the crop), the writer is inclined to believe that
it is not certain that the trouble will appear next year and there-
after with increasing severity. It seems most probable, aside
from a certain slight injury each year, that the character of the
season will largely determine whether or not serious injury,
like that of the present year, takes place. However, it is very
desirable for the growers to be well informed regarding the
nature of the trouble and to do what is feasible in the way of
preventive measures.
Experiments tried in the field. A number of observations
were made and a few experiments tried to determine the exact
nature of the trouble after plants had been set out in the field,
for it was very soon determined that the fungus was present
in the tobacco fields even in some cases where the growers had
not noticed it in their beds. In these experiments and obser-
vations it was aimed to determine three things, namely; (i)
Effect of transplanting diseased plants in the fields, (2) Effect
of transplanting healthy plants into infected soil, (3) Effect of
environment on the development of the disease. We will dis-
cuss these points briefly in the following paragraphs.
(i) Effect of transplanting diseased plants in the field.
Naturally a grower, when he has a diseased bed, uses only the
* The rainfall at New Haven for June was over 5 inches, giving an
excess of considerably over 2 inches when compared with the average
for thirty-four years. The excess for July was .68 of an inch.
360 CONNECTICUT EXPERIMENT STATION REPORT, I906.
best plants from that bed, if he uses them at all. Some growers
used plants from diseased beds, and seeing that they did not
start promptly, plowed them up. In one case at Portland, a
grower used at first the best plants from his diseased bed, and
then becoming scared, bought the remainder of his plants.
Those used from his own bed in the end made a more satis-
factory crop than those he bought, because calico developed
badly in the latter. He thought, however, that the plants from
the diseased bed did not do quite as well as plants ordinarily
did on the land in which they were planted. Another grower
at Bushy Hill used plants from his diseased bed, but soon after-
ward plowed them all up except one row, and reset with plants
from a healthy bed. At first the plants in the row that was
left did not seem as thrifty as the healthy plants reset later, but
at the end of the season they did not appear from a casual
examination to be much different, except that they had more
calico. In this same field one of the United States Govern-
ment experts had also set out a row each from healthy and
diseased beds. When, through the courtesy of the grower, the
writer examined these two rows at the end of the season, the
difference between them, if any, was not marked. Likewise
some plants from diseased beds set out at Tariffville for the
same purpose did not, to the writer, show any marked injury.
The only experiment tried by the writer was on the Experi-
ment Station grounds, with a few plants obtained from diseased
beds at Simsbury and Poquonock. These plants were set out
in three rows. In the first row the plants were entirely too
small for planting, and the roots were very badly injured.
Such plants were used because they were the worst that could
be obtained. In the second row the plants were in fair shape
and almost large enough for planting, but the roots were rotted
considerably. In the third row the plants were of fair size and
appearance, showing very little rot on the roots, and were
such plants as a grower would select as the best from the dis-
eased beds. The plants were set in soil free from the fungus,
and on a cloudy day, and were watered at first ; but they did not
have any special fertilization or cultivation. Unfortunately,
soon after they were set out, a heavy rain badly washed the
soil over some of the smallest plants in the first row, drowning
out a few, so that this may possibly have had some influence on
ROOT ROT OF TOBACCO. 36 I
their later growth. At the end of the season this test showed
the following facts: (a) That very few plants had been killed
outright by the root rot. (b) That at first those with badly
diseased roots were considerably retarded in growth, since they
had to form new roots, (c) That some of the badly diseased
plants in the first row made only a very stunted growth during
the whole season. Everything considered, those in the second
row made a very fair growth, despite the fact that they started
with considerable rot on the roots. Those of the third row
made the best growth, and were fair plants, (d) The final
examination of the roots on October ist showed that there was
then very little evidence of rot on them, even on the most
stunted plants, so that evidently the fungus had soon been out-
grown ; what damage it had caused was that done to the young
plants, from which injury apparently in the worst cases they
had never recovered. There was no calico on any of the plants.
Plate XXXII, b, shows a photograph of a part of these plants
taken on October ist, those in the foreground being in the
first row.
From these observations and experiments we may reason-
ably conclude that because rot appears in a bed it does not
necessarily mean that good plants taken from it will produce a
poor, or even an inferior, crop. That badly diseased plants will
do poorly, especially at first, there seems to be little doubt. That
good plants showing some disease, under some conditions will
do worse than under others, also seems certain. While we do
not advocate the use of plants from diseased beds if others can
be obtained, we do think that it is possible under certain con-
ditions of soil, moisture, etc., for the best plants from these
beds to do as well as plants taken from a bed not showing the
disease. However, the grower in this case must take a risk
that they will do as well.
(2) Effect of transplanting perfectly healthy plants in
infected soil. As the disease showed in some fields when the
plants were obtained from beds supposed to be free from the
trouble, there is question whether they became infected in the
field. If this were true, the fungus would evidently carry over
in these fields from season to season, doing more or less damage
as conditions were favorable or unfavorable, since tobacco is
grown on the same land year after year. We believe that
362 CONNECTICUT EXPERIMENT STATION REPORT, I906.
the fungus does become established in the fields in this way.
That perfectly healthy plants of the age for setting can become
infected when transplanted in infected soil is shown by the
following experiment. A grower at Poquonock had a bed that
showed the disease prominently, and after the plants were taken
from this bed on June 2d, at our request he set out thirty-nine
plants in it, which showed absolutely no sign of the disease on
their roots. On July 20th, see Plate XXXII, a, we examined
the roots of a third of these plants, and found more or less
root rot on all of them, and in some cases enough to cause
considerable injury. The plants were quite variable in size,
and not as thrifty as they should have been, but this in part was
due to the character of the soil, which was a fine, clay-loam
that easily became water-soaked. Later examination showed
the disease on the roots of all the plants. I have no doubt that
this close, wet soil was favorable for the development of the
root rot fungus, since it was the only bed at this place of this
character, and the only one in which the root rot appeared.
(3) Effect of environment on development of the disease.
We are quite convinced, aside from the presence of the fungus
in the soil, that the character of the season (especially the mois-
ture, and possibly unusually cold, wet spring weather) and the
character of the soil and subsoil (fineness, liability to become
water-soaked, drainage, amount of humus, especially in the
shape of manure) have much to do with determining whether
or not the fungus does much damage. We have tried growing
tobacco in soil from diseased beds and fields in the greenhouse
later in the season, but in almost all of these experiments the
root rot has not been as bad as it was in the open beds and the
fields presumably because the environmental conditions were
different. A fine clay soil that easily water-soaks, as in the bed
mentioned previously, seems to be one condition favoring the
disease, since one of the worst fields seen has a soil similar to
this. In another case, the use of a heavy filling of manure
beneath the seed bed for artificial heat, coupled with careless
watering and ventilating at a critical time, gave what the grower
desired, a rapid growth of the plants, but also admirable condi-
tions for the development of the fungus, which soon appeared.
To determine the action of fertilizers, a series of tests in dupli-
cate were started late in the fall in crocks in the greenhouse.
ROOT ROT OF TOBACCO. 363
with soil from two diseased fields. So far these tests do not
show any marked difference in the amount of rot (which is now
present on many of the roots but not doing conspicuous dam-
age), due to using carbonate of potash, high-grade sulphate of
potash, slaked lime, acid soil, or no fertilizer at all. There
does seem to be more of the fungus in the crocks where manure
was used, and in those crocks where the soil was treated with
formalin there is no rot at all. The experiment of course is
not yet completed, but so far it does not substantiate the com-
plaint made by ^ome growers against injury from artificial
fertilizers. The soil was taken from fields of a grower who
beheved that the excessive use of potash year after year had
been responsible for the injury. In these greenhouse tests
450 pounds per acre of carbonate of potash and 600 pounds of
high-grade sulphate of potash wera used ; but as the experi-
ment was not conducted under the same seasonal or field condi-
tions, this might make some difference in the results.
PREVENTIVE MEASURES.
Danger of infected beds. The common experience of the
growers whose seed beds were worst infected was that the
trouble had appeared in them last year to a limited extent.
This seems to indicate that the fungus, like most other soil
fungi, after it has become established in a bed will do more or
less injury each year — though no doubt the season and the
attention given the bed will influence its development. It
seems desirable, therefore, not to use the infected seed bpds
again for some time when new ones can be conveniently made.
Most growers, however, are reluctant to give up their old beds
either because of their handy location, the fine condition of the
soil or for other reasons. In these cases it will be desirable to
use some form of sterilization to eradicate the fungus.
Sterilisation of beds. Sterilization of the beds is helpful,
not only in preventing or lessening injury by the root rot and
dampening off fungi, but it also destroys more or less of the
weed seeds and insects. Three methods have been used with
more or less success on tobacco and other seed beds: ist,
Burning dry tobacco stalks or other fuel on the beds under a
metal cover, which throws the heat down into the soil, has been
tried somewhat in this state for destroying weed seeds. It is
364 CONNECTICUT EXPERIMENT STATION REPORT, I906.
said to be quite helpful in this respect, and it will probably also
kill the soil fungi, near the surface of the ground at least. Too
hot a fire, however, may burn out the humus of the soil or make
plant food less soluble and so do as much harm as good. 2d,
Sterilization by steam has been profitably employed against
soil fungi and nematodes in greenhouses and hot beds for
some time, and is now used in a few cases in this state to kill
the weeds in tobacco beds. There is no reason why it should
not be as successful in killing the root rot fungus as the other
soil fungi. There is on the market a steam rake whose points
when forced into a bed carry the steam into the soil from any
attached steam boiler. The chief objection to this method of
sterilization is the cost of the apparatus and the trouble and
time taken in heating the beds. 3d, Treating the soil with form-
alin is another method that is coming into use for combating
soil fungi. Preliminary tests with this method, as we have
already stated, were made the past summer against the root rot
fungus in the greenhouse and also in part of one of the badly
infected beds, see Plate XXX, a. The results from these tests
were so encouraging that we give the following tentative
directions for its use :
It is perhaps better to treat the beds in the fall so that they
may have a chance to dry out after the thorough soaking they
receive. If treated in the spring they should be aired for a
week before planting in order to allow the fumes of the form-
alin to escape and the soil to dry out as much as it will.
Whether in fall or spring, the bed should be treated after the
tillage is mostly done, for, if cultivated deeply after the treat-
ment, untreated soil containing the fungus may be brought up
from below. Commercial fertilizers may be used either before
or after the bed is treated, but manure, if used, should be put
on before so that it may be sterilized. Use only the strongest
formalin, guaranteed 40 per cent. This can be bought in car-
boys holding about 100 pounds for 10 cents per pound, or a
better article in pint bottles at about 40 cents. It is not neces-
sary, however, to get the chemically pure article, but it is
necessary to keep the bottles tightly stoppered to avoid loss of
strength through evaporation. One pint of this formalin
should be added to each twelve and a half gallons of water
used, or at the rate of one to one hundred by volume. This
ROOT ROT OF TOBACCO. 365
should be applied immediately to the bed with a sprinkling can
SO as to evenly and thoroughly wet the soil, using two-thirds
to one gallon to each square foot of surface. It may take some
time for the soil to soak in the latter quantity, but if applied
in partial amount it will soak in while the rest of the bed is
being treated. The ground should be covered with the sash
or canvas for a couple of days after treatment to help keep in
the fumes.
Sprinkling seedlings zvith formalin. According to our obser-
vations and experiments, a very weak strength of formalin
(about I to 1500) sprinkled several times on the plants in the
infected beds did not give very favorable results. So far as
the root rot is concerned we do not believe this treatment has
much value after the appearance of the disease. As regards
the dampening off troubles there was some evidence that this
method may have benefited the beds slightly. Possibly if this
treatment entirely supplanted the watering throughout the
whole season of the beds, it would prove more serviceable,
especially against the dampening oif fungi.
Treatment of the fields. It is more difficult to advise as to
the best treatment of the fields. Of course it is not desirable
to use plants from infected beds, if others are available. Care
in this respect, as stated before, does not necessarily mean that
the trouble will be escaped in the fields. One grower has sug-
gested that it might be well to use formalin in the water (i to
1200) when the plants are set out. While it is not likely that
this would prove of any great service, it might be worth trial on
a small scale, to determine its value. Some form of rotation
may be found necessary if the fungus persists in injuring each
succeeding crop. One field was seen the past summer, part of
which had been in corn the two previous years, and this part,
according to the owner, did better than the remainder of the
field; an examination of the roots also showed less of the rot
there. Where one has reason to suspect that his soil is acid,
it might be well to lime part of the field to see if this will prove
helpful to the crop. On the other hand, if a grower has been
using large amounts of potash (and the growers who used the
most were among those whose fields sufifered most) it might
be well to cut down the amount used on part of his field and
carefully compare this part with the remainder of the field
366 CONNECTICUT EXPERIMENT STATION REPORT, I906.
during the season in order to get data for determining the
character of his fertilization another year.
Examination of specimens. During the coming season any
grower who suspects he has this trouble in his seed beds or
fields is at liberty to send specimens of the plants or the roots
to the Experiment Station, at New Haven, for examination.
In cases of severe injury or especial interest, inspection of the
seed beds or the fields will be made if desired.
LITERATURE.
The following include all of the references in literature, of
any importance, that the writer has found relating to this
fungus.
1. Aderhold, R. Impfversuche mit Thielavia basicola Zopf. Arb. Biol.
Abt. Land. Fortw. Kaiserl. Gesundh. 4: 463-5. 1905. [Review :
Centr. Bakt. Par. Infekt. 15: 276-7. 1905-]
Made artificial cultures and inoculation experiments ; did not
find it a very aggressive parasite in the trials made.
2. Berkeley, M. J. and Broome, C. E. Notices of British Fungi.
Ann. Mag. Nat. Hist. II, 5: 461. 1850. pi. 11, f. 4.
Describes Torula basicola B. & Br. as a new species on base
of stems of peas and Nemophila auriculata from King's Cliffe,
England.
3. Cappelluti-Altomare, G. I semenzai del Tabacco e la Thielavia
basicola Zopf. R. Inst. Scafati 1902: 137-47. [Listed: Just Bot.
Zahrb. 30: 858. 1902.]
Have not seen this reference.
4. Fischer, E. Thielavia Zopf. Engl. & Prantl Nat. Pflanzenf. 1^:299.
1897.
Describes the genus and gives notes on the single species ;
places genus under family Aspergillaceae of the Plectascineae.
5. Frank, A. B. Thielavia basicola Zopf. Krankh. Pflanz. 2: 278
1896.
Gives a short general account of the fungus as taken from Zopf.
6. Jenkins, E. H. and Clinton, G. P. Root-Rot of Tobacco. Bull.
Imm. Inform. Conn. Agr. Exp. Stat. 4: i-ii. N. 1906. [Illustr.]
Give a general account of this disease in Connecticut.
7. Marchal, E. In Belgien im Jahre 1901 beobachtete pilzparasitare
Krankheiten. Zeitschr. Pflanz. Krankh. 12: 48. 1902. Ibid, 12:
239. 1902.
Reports Thielavia basicola killing roots of peas grown in water
cultures.
8. Orton, W. A. Plant Diseases. Yearbook U. S. Dept. Agr. 1901:
672. 1902. Ibid., 1903: 554. 1904.
Reports Thielavia basicola injurious in tobacco seed beds in
1901 and in 1903 in Ohio seed beds.
ROOT ROT OF TOBACCO. 367
9. Peglion, V. Marciume radicale delle piantine di Tabacco, causato
dalla Thielavia hasicola Zopf. Atti Reale Accad. Lincei V, 6: 52-6.
1897. [Reprint: Centrb. Bak. 3^: 580-3. 1897.]
Gives literature, botanical description of fungus, and records
injury in tobacco fields of Italy, where water-clogged condition of
soil favored the development of the fungus.
10. Saccardo, P. A. Thielavia basicola Zopf. Sacc. Syll. Fung, i:
39. 1882. Torula basicola. Ibid., 4: 257. 1886.
Describes these as distinct species but notes under former that
the latter is a conidial stage of it.
11. Saccardo, P. A. Clasterosporium fragile (Sorok.) Sacc. Sacc.
Syll. Fung. 4: 386. 1886.
Places Sorokin's Helminthosporium fragile under Clasterospor-
ium.
22. Selby, A. D. Diseases'caused by Nematodes. Bull. Ohio Agr. Exp.
Stat. 73: 228. 1897.
Found Thielavia basicola on roots of greenhouse begonias along
with nematodes.
13. Selby, A. D. Root Rot (Black Root). Bull. Ohio Agr. Exp.
Stat. 156: 95-7. 1904. [Illustr.]
Gives a short account of fungus and reports it in Ohio injur-
ing tobacco seedlings.
14. Selby, A. D. Soil Treatment of Tobacco Plant Beds. Circ. Ohio
Agr. Exp. Stat. 59: 1-3. O. 1906.
Gives suggestions for treatment of root rot based on experi-
ments used with success against the Rhizoctonia fungus.
15. Shamel, A. D. Another Blight strikes tobacco. Hartford Daily
Courant. 28 My. 1906.
Reports Thielavia basicola as causing serious injury to seed-
beds of tobacco in the Connecticut valley; recommends sprinkling
diseased plants with weak formalin.
16. Sorauer, P. Thielavia basicola Zopf. Handb. Pflanzenk. 2: 223-
1886.
Gives short note on fungus and gives Helminthosporium fragile
Son as a synonym.
17. Sorauer, P. Ueber die Wurzelbraune der Cjxlamen. Zeitschr.
Pflanz. Krankh. 5: 18-20. 1895.
Gives account of injury to roots of Cyclamen by Thielavia basi-
cola.
18. Sorokin, N. Ueber Helminthosporium fragile sp. n. Hedw. 15: 113.
Au. 1876. [Illustr.]
Describes the chlamydospores found on horseradish roots in
Kazan Bot. Garden as a new species.
19. Thaxter, R. Fungus in Violet Roots. Ann. Rep. Conn. Agr. Exp.
Stat. 1891: 166-7. 1892.
Reports this on violet roots in Connecticut, being first report of
the fungus in America.
368 CONNECTICUT EXPERIMENT STATION REPORT, I906.
20. Tubeuf and Smith, Thielavia basicola Zopf. Diseases of Plants :
182-3. 1897.
Give a short general account of the fungus.
21. Winter, G. Thielavia. Rab. Krypt. Fl. i": 53. 1887. [Illustr.]
Gives scientific description of genus and the single species
T. basicola, with short general account of injury by latter.
22. Zopf, W. Thielavia Zopf. Genus novum Perisporiacearum. Sitz.
Bot. Ver. Prov. Brandenb. 18: 101-5. 1876. [Reprint: Hedw. 16:
1 14-7. 1877.]
Describes this genus as new, placing Torula basicola B. &
Br. under it as its only species; describes four spore forms.
23. Zopf, W. Thielavia basicola Zopf. Die Pilze : 91. 1890.
Have not seen this reference.
24. Zopf, W. Ueber die Wurzelbraune der Lupinen eine neue Pilz-
krankheit. Zeitschr. Pflanz. Krankh. i: 72-6. 1891. [Illustr.]
Gives extended account of this fungus previously described by
him and a list of plants which he found it injuring.
PLATE XVII.
Apple.
a. Combined Winter and Canker Injury, p. 310.
Peon)'.
b. Root Injury or Rot, p. 318.
DISEASES OF APPLE AND PEONY.
PLATE XVIII.
Raspberry. X2.
a. Wilt of fruit, showing upper healthy and lower diseased, p. 321.
Tomato.
b. Black Mold, p. 329.
FUNGI OF RASPBERRY AND TOMATO.
PLATE XIX.
a. Cankered area extending on stem from ground upward.
b. Stem girdled under ground.
CANKER DISEASE OF TOBACCO, p. 325.
PLATE XX.
a. Showing rot of stem just above ground.
b. Showing cankered spots on older plants.
STEM ROT, Sderotinia sp., OF TOBACCO, p. 326.
PLATE XXI.
a. Effect of treatment in preventing Stem Rot fungus, p. 328.
b. Dampening off fungus at work among 3'oung plants, p. 326.
FUNGI OF TOBACCO SEEDLINGS.
PLATE XXII.
a. Leaf Spot of Russian Vetch, p. 330.
b. Speck Anthracnose of Violet, p. 331.
FUNGI OF RUSSIAN VETCH AND VIOLET, x 2.
Healthy,
PLATE XXIII.
Diseased.
a. Effect of disease on size of seedlings, p. 334.
b. Showing peculiar malformations of leaves, p. 332.
ONION BRITTLE.
PLATE XXIV.
a. Showing how disease spread across end of field, p. 333.
Untreated. + Treated.
b. Showing effect of treatment, p. 335.
ONION BRITTLE.
PLATE XXV.
a. Untreated rows that failed to respond to extra fertilization, p. 335.
Plots- 43 2
b. Adjacent treated rows photographed at same time and size as a, p. 335.
5 4 32 I
;'im^- ^-"^^^^^^
:J. ^^
c. Results of treatment on yields from adjacent rows, p. 335.
ONION BRITTLE, sliowing untreated and treated rows in detail.
PLATE XXVI.
a. After having been scraped oft", this new growth
was made in less than two weeks.
i *
J
' ' -A
i "
■ «'
dl
' i 4 ''it
t
b. Photo,ur;iplied just I2 days after <?, p. 340.
DRY ROT FUNGUS, Mcru/ius lacrvniaxs.
PLATE XXVII.
a. Showing growth made on plastering back of the wainscoting, p. 339.
b. Sterile mycelial strands formed on back of the boards, p. 339.
DRY ROT FUNGUS, Mcriilius hurymans.
PLATE XXVIII.
a. Immature fruiting stage, developing on front of board, p. 340.
Immature
Mature.
b. Fruiting or spore stage of the fungus, p. 340.
DRY ROT FUNGUS, Mcrulius lacrvmans.
PLATE XXIX.
Diseased.
a. Comparative size of healthy and diseased roots of seedlings, p. 350.
b. Showing badly rotted roots of seedlings. X 2.
ROOT ROT, Thidavia Imsicola, OF TOBACCO.
PLATE XXX
Treated.
Untreated.
a. Apparent effect of soil treatment with formalin, p. 354.
b. Showing rot in the fibrous roots of a field plant, p. 356.
ROOT ROT, Thiclavia basico/a, OF TOBACCO.
PLATE XXXI.
Healthy.
Diseased.
a. Appearance of the fungus on the large roots of field plants, p. 356.
Healthy. Diseased.
b. Effect of rot on roots of mature field plants, p. 35O.
ROOT ROT, Thiclavia basicola, OF TOBACCO.
PLATE XXXII.
a. Healthy plants that became diseased on transplanting in a diseased bed, p. 362.
b. Diseased plants transplanted in disease-free soil, p. 361.
ROOT ROT, Thielavia basicola, OF TOBACCO.
0(0
State Of Connecticut
REPORT
OF
The Connecticut Agricultural
Experiment Station
REPORT OF THE STATION BOTANIST, 190r
G. P. CLINTON, SC.D.
BEING PART VI OF THE BIENNIAL REPORT OF I907-I908
CONNECTICUT
REPORT OF THE BOTANIST
G. R CLINTON, ScD.
I. Notes on Fungous Diseases, etc., for 1907, p. 339.
II. Root Rot of Tobacco — II, p. 363.
III. Heteroecious Rusts of Connecticut having a Peridermium for their
aecial stage, p. 369.
ISSUED MAY, 1908
PART VI.
REPORT OF THE BOTANIST FOR 1907
G. P. Clinton, Sc.D.
I. NOTES ON FUNGOUS DISEASES, ETC., FOR 1907.
GENERAL NOTES ON DISEASES PREVIOUSLY REPORTED.
Weather conditions. Even more so than the previous year,
1907 v^as characterized by comparatively little injury to plants
from fungous diseases. This does not mean that it was an excel-
lent year for crops, for, on the contrary, it was an unusually poor
one, since the conditions that proved unfavorable for serious
attacks by fungi also prevented good plant growth. These
unfavorable conditions were chiefly those of the weather. To
begin with, there was some winter injury to the fruit buds,
especially those of the peach, which, except in restricted localities,
were largely killed before spring, so that the peach crop was a
practical failure for the state. Some injury, too, was done to the
young twigs, but there was no such serious injury to the trees
in general, as was experienced during the winter of 1903-04.
The spring was very backward, so that up to the middle of
May the work of the market gardeners was about a month behind
the usual time. Coupled with the late spring were two unusual
frosts on May nth and May 21st, which did considerable damage
to the exposed tender vegetation, and the blossoms developing at
that time. Especially there should be mentioned frost injury
to the unprotected early tomatoes, to strawberry and grape
blossoms, and to the unfolding foliage of the sycamores.
Following this late spring came an unusually dry summer,
including most of the months of June, July and August. The
total rainfall for these months was only 5.49 inches, as compared
with the average of 12.80 inches during the past thirty- four
years, as shown by the records of the United States Weather
25
34° CONNECTICUT EXPERIMENT STATION REPORT^ I907-I908.
Bureau at New Haven. This drought was felt over the entire
state, but was especially severe in certain districts, so that the
yield of most of the crops was very materially decreased. The
drought was not broken in the vicinity of New Haven until
August 24th. Fortunately, the fall, both as to its length and
the amount of moisture, proved fairly favorable for vegetation,
so that crops which were not too severely damaged made good
gains during this period. The more important of the previously
reported fungous and physiological troubles of the year are
briefly discussed under the following heads :
Apple, Little injury was done by either the sooty blotch or
apple scab. On the other hand, the fruit speck trouble, first
described in our Report for 1905, p. 264, was more conspicuous
than usual. We have not been able to study this trouble further,
so that the particular fungus responsible for it is still in doubt.
Since our first report, we have had complaint of it from Pennsyl-
vania and New Hampshire, and this year it was said to have
caused very considerable damage in Maine. The writer was also
told that it was a very common and injurious trouble with apples
on the Boston market the past season.
Baldwin spot is another trouble that was more prominent than
usual. It was seen on the Greening, and some fall varieties, as
well as on the Baldwin. The fruit at storage time showed little
of the trouble, though it soon began to develop, and continued
evident up to the end of the season. The reddish-brown diseased
spots often appear entirely within the flesh, but may work out-
ward so as to form a slightly sunken discoloration in the epider-
mis, as shown in the illustration, Plate XVH, a. On cutting the
apple, the tissue of these spots was often torn rather than cut
sharply across, indicating a tougher or more spongy texture.
Microscopic examination revealed no fungous threads or bacteria
present. The cell contents were more or less disorganized, colored
reddish-brown and in some cases there was more starch present
than in the surrounding healthy tissues. Cultures, attempted both
in December and February from isolated spots in the interior,
gave absolutely no growth of any kind, thus confirming the results
of previous investigators that this is not a parasitic trouble. After
these spots reach the surface they may offer entrance for fungi
causing true rot, especially that caused by the blue mold. The trou-
NOTES ON FUNGOUS DISEASES FOR I907. 34 1
ble seems to be physiological, and possibly bears some relationship
to the weather, especially to drought such as was experienced
the past season. It was suggested by one grower, whose apples
were rather badly affected, that injury by the aphis, when the
apples were quite young, might be the starting point of the
trouble.
Market Garden Crops. Early in the season some of the
cucurbits, especially the cucumber and muskmelon, suffered con-
siderably from the bacterial wilt, but this did not progress, so that
where the stand was sufficient the injury was not so great as was
expected at first. Onion brittle, or something very similar to it,
was more general all over the state than ever before, and some of
the crops while quite young were very severely injured. Further
study of the trouble did not throw any additional light upon its
cause. The onion crop as a whole was fair, since seed onions
suffered little, if any, from the blossom blight, and the black spot
did little injury to the bulbs of the white varieties.
Tip burn was the only serious trouble of the potato ; but this,
because of the drought, was so severe that the crop was cut very
short in many fields. There was practically no complaint of rotten
tubers, and it was only after the most diligent search during the
entire season that the blight fungus was finally found on a few
green vines at Storrs and at this station about the first of October.
In the fall, market potatoes from Maine, however, showed con-
siderable injury from blight, and were seriously objected to by
the buyers for a time.
During the drought the tomatoes suffered considerably from
the point rot trouble, which was a frequent source of complaint
by growers. After the drought it was less evident, which seems
to indicate that it was a physiological rather than bacterial or
fungous trouble. The Lima bean mildew was not seen during
the whole season, though looked for in fields where frequently
it is very troublesome.
Ornamental Plants. No very serious or unusual troubles of
ornamental plants were found other than those reported under
new diseases, except possibly yellows of asters and the leaf spot
of the European horse chestnut, which was certainly unusually
conspicuous after August. Leaf scorch injuries of shade and
forest trees due to the drought were not uncommon.
342 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
Peach. The leaf fall trouble mentioned in our last Report, p.
317, was even more conspicuous than last year. A thorough
examination was made of one of the orchards where it showed
most prominently, and the trees were found with their wood
severely winter injured, while those not suffering were free
from winter injury. This winter injury, coupled with the severe
drought, was, in our opinion, the cause of the trouble, especially
in orchards where the soil could not be thoroughly tilled to con-
serve the moisture. Yellows is another trouble that showed signs
of being greatly on the increase. One prominent grower estimates
that fifty per cent, of the trees in the state are now infected with
yellows. Mr. Waite, of the United States Department of Agri-
culture, states that Connecticut is at the northern end of an area
reaching along the Middle Atlantic coast in which there is a
very severe outbreak of this trouble. Whether or not the outbreak
in this state is as severe as some suppose, remains yet to be seen,
since the premature development of the buds last fall, taken as
one of the signs, may have resulted from the wet fall following
the prolonged summer drought.
Tobacco. There was some complaint, especially in the region
of Granby, of injury to tobacco beds from the root rot fungus.
Tobacco in the field finally did somewhat better than was expected
after its injury by the drought, but upon curing, the quality was
said to be below the average, and the price obtained was much
lower than usual. There was again evident injury in certain
fields near Sufifield that could not be laid to the weather; and,
so far as the writer could determine, did not seem to be entirely
the work of the root rot fungus, but was possibly due to unknown
soil conditions of a chemical nature.
DISEASES NEW TO THE STATE.
While this year developed few serious fungous outbreaks,
at least the usual number of new diseases were found. About
one-fourth of these troubles are of physiological rather than of
parasitic origin, and such are indicated by italicized common
names in the following accounts :
APPLE, Pirus Mains.
Spray Injury. Plate XVII, b. We have mentioned before
(Report for 1903, p. 303) the ordinary forms of Bordeaux
NOTES ON FUNGOUS DISEASES FOR I907. 343
injury, such as spotting of the leaves, and russeting of the fruit.
Last December there were sent to the station, by Mr. E. A. Moore
of New Britain, Baldwin apples that showed a form of injury
which we had not seen before. These apples had been
sprayed several times with Bordeaux and lead, the last application
being made about the middle of August. When examined, the
fruit still showed more or less of the spray in the stem and bloom
ends. The injury consisted of small specks, as shown in the
illustration, reaching but slightly beneath the epidermis, and
clustered chiefly at the bloom and stem ends. Evidently some
injurious ingredient of the spray had in time become dissolved
and been carried into the tissues, probably through the lenticels
or insect punctures, kilHng the cells with which it came in imme-
diate contact. The damage resulting from this kind of injury
is not nearly so serious as the more common forms.
BEAN, LIMA, Phaseolus lunatus.
Chlorosis. The past summer a trouble of Lima beans was seen
on occasional plants that was somewhat similar in appearance
to the calico of tobacco. It shows as a yellow mottling of the
tissues, the chlorophyll usually retaining its normal color in the
vicinity of the larger veins. Attempts to produce the same trouble
on healthy plants by touching the leaves with juice from the
diseased tissue, as can easily be done, in the case of calico of
tobacco, were not successful, thus indicating that the chlorosis
is not of an infectious character. Just what conditions produce
this trouble is not known, and, since not serious, it is chiefly
of interest because of its general resemblance to the chlorosis of
variegated plants.
BELLFLOWER, Campanula rapunculoides.
RusT^ Coleosporium Campanulae (Pers.) Lev. Plate XXV.
This rust was found in October causing some damage to plants
in a New Haven nursery, where it had been noticed by the
owner for a few years past. The uredinial or. II stage is the
one that does most injury, since this is chiefly influential in
spreading the trouble. It shows as dusty orange outbreaks
about the size of small pinheads scattered or clustered on the
under side of the leaves. Sometimes there is a slight discolora-
344 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
tion of the upper surface. The III stage occurs late in the
season, as very small, slightly elevated, reddish, waxy areas also
on the under side of the leaves. Kellerman has shown that the
I stage of this fungus occurs on the needles of the pitch pine, from
which it goes to the Campanula. The III stage carries it back
to the pine. This fungus is further discussed in the last article
of this Report.
BITTERSWEET, JAPANESE, Celastrus artkulatus.
Crown Gall, Bacterium tumefaciens Sm. & Towns. The
above is a new host for the crown gall, at least for Connecticut.
Dr. Britton found the infected specimens while inspecting a
nursery in New Haven. The galls are so similar to those found
on the peach and other hosts in this state that there is no
reason for believing them different or caused by a different agent.
New interest has been aroused concerning the crown gall because
of the recent publications of Smith and Townsend (Science 25:
671-3. Ap. 1907. Centr. Bak. Par. Inf., II, 20: 89-91. D.
1907) of the United States Department of Agriculture, who seem
to have proved that crown gall on its various hosts is caused
by the bacterial organism named above instead of by a slime
mold, as claimed by Toumey, the first extended investigator of
the trouble. They were able to produce galls on peaches and a
variety of other plants by inoculation with pure cultures of this
bacterium obtained originally from galls on cultivated marguerite.
BLACKBERSY, Ruhus villosus.
Rust, Kuehneola alhida (Kuehn) Magn. This forms much
less conspicuous and injurious outbreaks than the orange rust.
which attacks the same hosts. The II stage of the fungus was
found at Storrs on leaves of the cultivated blackberry, but was not
very prominent on these, being much more luxuriant on the wild
swamp blackberry. However, it sometimes proves an injurious
pest, as Stone of Massachusetts (Ann. Rep. Hatch Exp. Stat.
9:74. 1897) has reported a case in which considerable damage
was done in 1894 to cultivated varieties in that state. The II or
injurious stage shows as very small, yellowish-orange, dusty out-
breaks on the under surface of the leaves. The final article of
this Report contains further information concerning the fungus.
NOTES ON FUNGOUS DISEASES FOR I907. 345
CHESTNITT, Castanea sativa americana.
Chestnut Bark Disease, Diaporthe parasitica Miirr. Plate
XVIII, a. Mr. F. V. Stevens, Jr., tree warden of Stamford,
informs the writer that the chestnut disease, which has proved
so serious in the vicinity of New York City and on Long Island,
has become common in the neighborhood of Stamford. He also
reports having seen the trouble in one or two other places in the
state. Dr. Murrill, of the New York Botanical Garden, has car-
ried on extended investigations during the past three years, and
finds that a particular fungus is responsible, for the injury. This
fungus produces cankers in the bark, and in time becomes so
general on an infected tree as often to kill it. While most
injurious so far to the native chestnut, it also occurs on the
chinquapin and the European chestnut, but has been found only
occasionally on the Japanese.
Both Murrill and Metcalf, of the United States Department of
Agriculture, who has also made a study of the trouble, take a
rather alarming view of the danger to all chestnuts in infected
regions. Mr. Metcalf (U. S. Dept. Agr. Bur. PL Ind. Bull. 121,
VI. 1908) says: "Unless something now unforeseen occurs to
check its spread, the complete destruction of the chestnut orchards
and forests of the country, or at least the Atlantic States, is only
a question of a few years' time." While the trouble is no doubt
a serious one, we are inclined to believe that its power of spread-
ing and the likelihood of its annihilating all the trees of infected
regions, have been overemphasized. Spraying against the trouble
seems not to have proved either practical or effective. Pruning
off all diseased branches has not always been successful in
freeing the trees of the disease, or if so, they have become
re-infected through the wounds.
Whether or not the trouble is the same, serious injury to
native chestnuts and chinquapins has been reported before from
different parts of the United States, We quote the following
from an article by Mr. Jones, of Georgia, which appeared in
the American Journal of Science and Arts, vol, I, page 450, in
1846 : "The present remarks are particularly directed to the death
and disappearance of some of our trees and shrubs. The first
that I will mention is the Castanea pumila, which is a tree from
ten to thirty feet in height. In the year 1825, during the months
346 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
from June to September, I observed this tree dying when in full
leaf and with fruit half matured. I examined numerous individ-
uals, and could find no internal cause for their dying. I at first
attributed it to the great fall of rain which took place in the
year 1823, for during the month of July of that year a considera-
ble quantity of land, not subject to overflow, was covered with
water for some time, and the highest lands were completely
saturated. The latter part of 1824 was also very rainy. Knowing
that this tree belongs in our highest and driest soils, I concluded
that it was owing to a too moist state of the ground. But since
that time I am convinced that there must be some other cause,
for the tree continues still to die up to the year 1845, and if the
disease is not arrested, in a few years I fear it will be entirely
exterminated."
Dr. Mohr, writing more recently, 1901, in Plant Life of Ala-
bama, says concerning the chestnut in that state : "The chestnut,
usually one of the most frequent trees of these forests, is at
present rarely found in perfection. The older trees mostly show
signs of decay, and the seedlings as well as the coppice growth
proceeding from the stump, are more or less stunted. It is
asserted by the old settlers that this tree is dying out all over the
mountainous region, where at the beginning of the second half
of the century it was still found abundant and in perfection."
COW PEA, Vigna sinensis.
Leaf Blight, Cercospora Dolichi E. & E. This fungus forms
reddish subcircular or angular spots, about one-eighth to one-
quarter of an inch in diameter, usually scattered over the leaves
and showing through on both surfaces. With age these spots
sometimes have a greyish center. By the aid of a hand lens the
fruiting stage of the fungus can often be seen on the spots
as an inconspicuous coating of very short olive-black threads.
Two or three other species of Cercospora (C cruenta Sacc, C.
Vignae E. & E., C. Vignae Racib.) have been described on species
of Vigna, or Dolichos," as it is sometimes called, which possibly
may not be distinct from this. On some of these spots a species of
Alternaria occasionally occurs, but perhaps only as a saprophyte.
Leaf Spot, Amerosporium oeconomicum E. & T. A second
fungus frequently appears on the same leaves with the preceding,
NOTES ON FUNGOUS DISEASES FOR I907. 347
producing very similar spots. However, the latter can be dis-
tinguished in its mature state by having spots vi^ith a reddish
border and whitish center in which the fruiting stage shows as
minute black imbedded bodies. In the N. A. F. no. 2574, on
Dolichos arvensis, Ellis & Everhart issued a specimen which they
named Amerosporium Dolichi E. & E, n. s., which does not seem
to be different from our species described by Ellis & Tracy three
years before (Journ. Myc. 4: 102. 1888). These exsiccati speci-
mens plainly show that the spores are septate (about three septa)
when 'old, and the specimens collected in Connecticut also indicate
that they would become septate with age. This may mean that
the fungus belongs in a different genus, since the spores of Amer-
osporium are said to be continuous.
In the specimens collected at Storrs in September, besides the
Cercospora and Amerosporium, the leaves also had numerous
more or less elevated reddish spots or specks the size of a pinhead
or less. While these may be the beginning of the fungous
troubles already mentioned, they look very much like injuries
caused by sucking insects. Altogether the spotting caused by
these various agents becomes quite conspicuous, and causes
considerable injury to the leaves.
CURRANT, Ribes ruhrum.
Bitter Rot^ Gloeosporium rufo-maculans (Berk.) Thuem.
Plate XVIII, c. During the latter part of July, in a small plan-
tation at Storrs, the white currant was found rather badly affected
with a fungous trouble that caused the berries to gradually shrivel
and dry up into wrinkled mummies. The fruiting stage of the
fungus shows under a hand lens as minute black specks, fre-
quently with a lighter center, but these may become obscured
by the small masses of pinkish spores that ooze out on the surface.
At the same place, but not necessarily on the same bushes, there
was also found a small amount of anthracnose, Gloeosporium
Ribis (Plate XVIII, b), that often attacks currant leaves. In
passing it might be noted that Klebahn (Zeitschr. Pflanzenkr.
16: 65-83. 1906) has recently shown that this fungus is the
conidial stage of Pseudopesisa Ribis n. s. that develops on the
fallen leaves in the spring. At first it was believed that the fruit
disease was also caused by this Gloeosporium, although it is not
348 CONNECTICUT EXPERIMENT STATION REPORT^ I907-I908.
commonly reported on the fruit, Stewart, in Bulletin No. 199 of
the N. Y. Exp. Station, being the only one known to the writer
who has found it on the fruit and stems as well as on the leaves.
Microscopic examination, however, showed that the spores from
the berries and leaves were quite different in appearance. The
spores from the leaves were chiefly 16 — 20/x by 5 — 6ju,, and
decidedly curved, being usually bow-shaped and often tapering
to the ends ; while the spores from the fruit were straight, less
tapering, and somewhat narrower, varying chiefly from 14 — 22/a
by 4 — 5)U,. So similar are the spores to those of the bitter rot
fungus, especially to grape rot mentioned in our last Report
(1906, p. 314), that we have decided, at least for the present,
to consider the fungus the same, though it has not before been
reported on the currant as a host. We have found no other
Gloeosporium mentioned as occurring on the fruit of currants,
though Gloeosporium ribicolum E. & E. was described on the
fruit of Ribes sp. (cultivated gooseberry). A few days after
collecting the fungus at Storrs, the white currants on the Experi-
ment Station grounds at New Haven were examined, and the
fruit of these was found to be somewhat similarly injured.
Microscopic examination, however, showed that in this case
the Gloeosporium present was different, the smaller spores varying
chiefly from 7 — I5/^ by 3 — 6/x. As many of the shriveled berries
showed no signs of this fungus, it is quite probable that it occurred
here as a saprophyte, and the trouble was really due to some other
cause, possibly the very dry weather. The spores of this fungus
were similar to those of G. ribicolum, except slightly broader.
Powdery Mildew, Sphaerotheca mors-uvae (Schw.) B. & C.
Plate XIX. While the powdery mildew has been reported from
Connecticut on the gooseberry, this is the first mention, so far as
known, of its occurrence on the currant. Specimens were found
in July on red currants in a nursery at Storrs, where it confined
its attacks to the ends of the young branches and their leaves,
the latter being checked in their development. At the same place
the fungus occurred on the gooseberry, but limited its attacks here
to the fruit. The dirty white or brownish mycelium forms a
thickish felt (in which are imbedded the fruiting bodies as dark
specks) on the affected parts, and is thus directly exposed to
fungicides when applied. However, to secure good results, the
NOTES ON FUNGOUS DISEASES FOR I907. 349
treatment must be started before the appearance of the trouble,
since the plants infected in this case had been sprayed, apparently
tardily, with Bordeaux, with little effect.
FALSE INDIGrO, Baptisia australis.
Powdery Mildew, Erysiphe Polygoni DC. This fungus has
been noted before from the state on several hosts, such as the
columbine, crowfoot and pea, but this is the very first report,
apparently from anywhere, of its occurrence on the above host.
The mycelium forms a luxuriant growth on either side of the
leaf and an abundance of the perithecia were developed. Alto-
gether, it caused considerable disfigurement of the infected plants,
which were growing in a local nursery.
FERN, Adiantum Farley ense.
Leaf Scorch. Plate XX, a, gives a good idea of the appear-
ance of this trouble of the Farleyense fern. It was first seen by
the writer in the fall of 1902, in a Connecticut greenhouse, where
it was quite troublesome. Complaint was made of it again in
January, 1907, by Mr. A. N. Pierson, a large grower of ferns at
Cromwell, who sent specimens for examination. The trouble
shows on the leaves as prominent, often wedge-shaped, reddish-
brown areas that extend inward from the clefts of the pinnae.
These spots give a variegated appearance to the plants, which
produce a less luxuriant growth, but otherwise appear in
a healthy condition. A careful microscopical examination of
the roots, stems and leaves showed no indication of any bacterial
or fungous parasite. There seemed to be no unfavorable condi-
tions of the soil to produce the injury. It appeared on the whole
to be a physiological trouble. So far as the writer could deter-
mine, it seemed to be a leaf scorch, not necessarily entirely
due to hot rays of the sun, but to loss of moisture from the
leaves under unfavorable conditions, such as too dry an atmos-
phere, sudden changes of air moisture, etc. A somewhat similar
trouble has been seen occasionally in nature where ferns suffered
from lack of moisture. The Farleyense fern is very delicate, and,
because of its very thin leaf tissues, is much more sensitive than
other cultivated ferns to unfavorable conditions. The fact that
35° CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
the trouble seems to start near the veins, and that under the
microscope the stomates often show discoloration before the sur-
rounding cells, indicate that it is a trouble connected with the
inability to properly control transpiration of moisture. While
no doubt it is a common trouble, and probably noted before in
floral writings, the writer has seen no mention of it in the
literature of plant diseases. Halsted (Ann. Rep. N. J. Exp. Stat.
14: 420. 1894) describes and figures a somewhat similar trouble
caused by a definite fungus (Phyllosticta Pteridis Hals.), and
briefly states that unfavorable environment also often causes ferns
to die and turn brown at their tips. Concerning the Farleyense
trouble, Mr. Pierson wrote : "I do not think it is due to sun
burn or scald, because the disease, which we have always called
rust, is hardly noticeable in the summer time, but rather when
the cold, damp weather comes on in the winter ; particularly is it
so this year. These very same plants that look so badly, with
hardly a perfect leaf on them, will, by cutting the old leaves
away, throw up perfect leaves in the spring, without a spot on
them, and can be sold for decorative purposes." This last state-
ment seems also to indicate that this trouble is a physiological
rather than a parasitic one.
HEMLOCK, Tsuga canadensis.
Rust, Caeoma Ahietis-canadensis Farl. This rust shows as
small orange-yellow pustules on the leaves. Apparently it is never
injurious to cultivated hemlocks, as it has only been found once,
and then in very small amount, on a tree in a yard in Westville.
Rust, Peridermium Peckii Thuem. Plate XXIX, a. Another
rust quite distinct from the preceding also occurs here on the
hemlock. It forms small, cylindrical, white receptacles, usually
in double rows, on the under surface of the leaves. In time these
peridia rupture and discharge the orange-colored spores. The
rust has been collected a number of times the past year, both on
cultivated and native hemlocks, but never occurred in such
abundance as to cause any noticeable injury, though the few
infected leaves are shed prematurely. J3oth of these rusts are
discussed further in the final article of this Report.
NOTES ON FUNGOUS DISEASES FOR I907. 35 1
HERBACEOITS PLAHTS, Delphinium sp., Funkia sp., Pentstemon
harhatus, Valeriana officinalis.
Stem Rot^ Undet. sclerotial fungus. Plate XXI. A serious
soil fungus was found last fall in a New Haven nursery doing
considerable injury to a variety of herbaceous plants, especially
to the Valeriana and Pentstemon mentioned above. The myce-
lium attacks the parts of the plant at or near the surface of the
ground, frequently rotting off the stems. In the fall it forms
subspherical reddish sclerotia both in the tissues and in the soil
nearby. Pure cultures were obtained, and while the fungus
grows luxuriantly, it has never produced a true spore stage. The
sclerotia form as swellings at the tips of clustered threads, and
are at first whitish, but soon turn reddish-brown on the outside.
Their size depends somewhat on the character of the medium
used in the cultures. Plate XXI, b, shows sclerotia on nutrient
potato agar, which are quite similar to those found in nature,
and others, grown in nutrient corn meal agar, which are much
larger and more irregular. In artificial cultures made from the
sclerotia these give rise to similar sclerotia, but what they will
produce in the soil has not yet been determined. According to
Professor Thaxter, they are probably the sclerotia of some
hymenomycetous fungus.
JUNEBERRY, Amelanchier canadensis.
Rust, Gymnosporangium clavipes C. & P. Plate XX, b.
The I stage (Roestelia aurantiaca Pk.) of this fungus has often
been seen on specimens of wild juneberry, but last July it was
also found on cultivated specimens in the nursery at Storrs. It
occurs most commonly on the fruit, the fringed white receptacles,
containing bright orange-colored spores, often thickly covering
the berries. The III, or mature stage, occurs on the cedar, so
that the trouble is easily controlled by excluding this alternate
host.
LAUREL, MT., Kalmia latifolia.
Leaf Spot, Septoria Kalmicola (Schw.) B. & C. The native
mountain laurel is often grown for ornament in Connecticut, and
the last legislature made it the state flower. Any fungus causing
injury to it thus becomes of interest. The leaf spot mentioned
352 CONNECTICUT EXPERIMENT STATION REPORT^ I907-I908.
above is a very common trouble on both the wild and cultivated
plants. Its chief injury consists in greatly marring the appear-
ance of the leaves. The subcircular spots produced by it are
scattered over the leaves, and reach a maximum size of about a
quarter of an inch, except when closely placed, they may run
together and form a more extended injury. They have a definite
purplish border, with a greyish center on the upper surface in
which the small black fruiting receptacles can be seen with the
naked eye. Often on the same leaves other somewhat similar
spots are present, but are distinguished by having a reddish-
brown rather than a greyish center. The immature fungus found
on these could not be determined, but the spots look like those
of Phyllosticta latifoliae E. Si E.
MEADOWSWEET, Spiraea {Ulmaria) sp.
Anthracnose, Cylindrosporium sp. We have not been able
to determine specifically this leaf fungus ; but, from lack of
definite fungous walls in the imbedded receptacles, it seems to
be a Cylindrosporium rather than a Septoria, though the spores
are narrower than those of C. Filipendulae. A number of species
belonging to these two genera have been described as having
Spiraea for a host, and there seems to be some confusion regard-
ing them. This particular fungus has spores more or less curved,
with usually some indication of septa, often five when mature.
The spores vary in size from 35 — 50/^ by 2ju,. Frequently the
spore masses can be seen with a hand lens as minute white
tendrils that have oozed out on the upper surface of the leaves.
The spots are purplish, most evident on the upper surface, rather
thickly placed, and generally are one-eighth of an inch or less in
diameter. This fungus causes considerable injury to certain of
the cultivated varieties of Spiraea; the one mentioned here was
collected in a New Haven nursery on plants labeled Ulmaria
purpurea elegans.
OAK, WHITE, Quercus alba.
Anthracnose, Gloeosporium canadense E. & E. This fungus
injures the leaves, most frequently near the margins, where the
tissues die and dry up into light brown areas of considerable
extent. Isolated spots, surrounded by perfectly green tissue,
NOTES ON FUNGOUS DISEASES FOR I907. 353
also occur. The trouble is very similar to the leaf scorch of
oak, and often one is not entirely sure, even after a microscopic
examination, which is which. The specimens reported here Vv^ere
sent from New Canaan by Mr. A. L. Benedict, who complained
of injury to his trees.
PINE, SCOTCH, Pinus sylvestris.
RusT^ Peridermium pyriforme Pk. Plate XXVIII. The writer
has recently shown that this rust is merely the first stage of
Cronartium Comptoniae Arth., which has the sweet fern for its
alternate host. The first stage has been found in Connecticut
on the pitch as well as the Scotch pine. The rust on the Scotch
pine was first found by the State Forester, who had noticed for
several years that a number of these young pines in the state
plantation at Rainbow were attacked by some fungus. This rust
occurs only on the stems, usually at the base of the young tree,
and as its mycelium is perennial, appears year after year in the
same specimen. It causes a slight swelling of the trunk, and
considerable injury to the bark and young wood, so that badly
infected young trees are no doubt sometimes killed. In time
the spores are scattered, and all signs of the fruiting stage disap-
pear, so that by the end of July the infected trees are not readily
detected. The trouble should be easily controlled by destroying
infected branches and young trees and keeping down the sweet
fern in the neighborhood. This fungus is further discussed in
the final article of the present Report.
PINE, WHITE, Pinus Strohus.
Pine Blight. Plate XXII. This so-called blight was one of
the most conspicuous diseases of the year, since it occurred quite
generally not only in Connecticut, but over most of New England.
More complaints of the trouble, all after the middle of August,
were received at the station than of any other for the year.
Its widespread appearance caused general alarm and discussion,
and an extended and intelligent account of it appeared in the
Boston Transcript of August 20. The same, or a very similar
trouble has been under observation for several years past by Pro-
fessor Stone of the Massachusetts Experiment Station, who first
noticed it after the severe winter of 1903-04. He attributes it to
26
354 CONNECTICUT EXPERIMENT STATION REPORT^ I907-I908.
winter injury, and its prominence the past year to the unusually
dry summer. In our last Report (1906, p. 320) we mentioned
a case in this state which was also apparently due to winter
injury. There is no question that the trouble, whether or not
always due to the same causes, has been more prevalent this
year than ever before.
The most serious complaints were from the northwestern part
of the state, where many of the older trees were reported as
seriously affected. The writer's observations were made after
the first of August, chiefly on small trees from five to fifteen
feet high in a Westville nursery and in the state plantation at
Rainbow. We have seen no sign of the trouble in the nursery
seedlings. In most of the cases examined the leaves were killed
from their tips inward for about a third or two-thirds of their
length, the dead tissues turning a reddish-brown color. Some-
times there was an inconspicuous yellowish spotting on the tissue
below the dead area. This year's leaves were the most frequently
injured, and in all cases were undersized, thus indicating the
trouble at least began before the leaves reached maturity. In the
fall often one or more of the leaves in a bundle dropped out, and
no doubt all are shed prematurely. Occasionally a tree was
seen with all the leaves dead, in which case there was no hope
for it, as usually the roots were also dead. Most of the trees
examined, however, showed no signs of injury to the trunk or
root, such as a severe winter freeze might make ; but the smallest
fibrous roots were sometimes somewhat dried out, thus indicating
possible suffering from lack of moisture.
Most persons have been inclined to consider this trouble the
result of fungous attack. One firm claims to have sprayed trees
with good results. This, if true, the writer believes to be due to
stopping the transpiration of water by clogging the stomates,
rather than to any fungicidal effect. We see absolutely no
reason for believing the trouble due to a parasitic fungus on
the leaves. The fungi found on the injured leaves were of the
nature of saprophytes, being more or less tardy in their appear-
ance. Then, too, the widespread injury to practically all of the
leaves of the affected trees, while adjacent interlocking trees were
often entirely free, is against any such theory. The dry season
was also unfavorable for such a sudden and widespread injury
NOTES ON FUNGOUS DISEASES FOR I907. 355
by fungous agents. We have had seedlings for several months in
the greenhouse with their leaves interlocked with leaves from
diseased trees with no sign of contagion. Since the trouble is
so general in its effect on the tree, a fungus, if the cause, would
more naturally be found at work on the roots. As yet we have
obtained no satisfactory evidence that a soil fungus is the cause
of the trouble. In fact, the evidence in the main is against such
a beHef. We have seen some dead trees with a fungous growth
on their roots and in the surrounding soil ; and in one case young
pines were planted in pots containing soil with such a fungus,
but with no injury to the pines after several months' exposure.
There seems to be no reason in the opinion of the entomologists
who have examined the injured trees for believing that the
trouble is caused by insects.
Everything considered, the trouble seems to be a physiological
one, brought on by adverse conditions. In some cases winter
injury alone probably accounts for it. In this state during the
past year, it is apparently largely due to the drought ; or possibly
the late frosts of May ii and 21 may have injured the protruding
tips of the young leaves and thus have been altogether respon-
sible for the unusual prominence of the trouble. The pine needles
grow from the base, so that the exposed young tips could have
been killed. or injured and a growth still be made from the pro-
tected basal part. In the case of the sycamores, which we know
suffered from these frosts, the whole of the young leaf was
exposed, and so was entirely killed. In view of these possible
and at the same time unusual causes, we do not look for the
trouble to be so prominent the coming season as last year.
POTATO, Solanum tuberosum.
Internal Brown Spot. Plate XXIII, a. The writer first
saw this trouble in Connecticut in potatoes that were imported
from- Scotland in 1906 f6r experimental purposes. It was espe-
cially bad in the Midlothian Early variety. The past year it
was also found not uncommon in certain of Mr. East's numerous
varieties, especially in those of European origin. Among the worst
affected of the varieties were Sutton's Field Ash Leaf, Alderman,
Harbinger, Royal Ash Leaf Kidney, Britannia, Snowball, and
Early Maine, of which the last only is of American origin. A
356 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
few Connecticut growers have complained of trouble similar to
this, and Morse (5) also reports it from Maine in 1907.
The trouble is in no sense a true rot. The affected tubers may-
or may not show the disease on the outside. Usually, however,
some indication of its presence is given by a slightly shrunken
appearance and a reddish discoloration of the skin. When cut
open, the tubers show a conspicuous reddish disease of the tissues.
This may occur in isolated spots scattered through the healthy
flesh, having no apparent connection with the exterior, or there
may be a band starting from the exterior and progressing more
or less deeply inward. Taken as a whole, the trouble most fre-
quently starts at the stem end and works toward the bud
end and inward. In the cases where the trouble shows as a
band at the surface, it can scarcely be told from the blight disease
caused by Phytophthora. In some of the worst affected European
varieties the spotting finally runs all through the tuber, appearing
much worse than that shown in the illustration. Often the
spots have a watery appearance, especially in varieties poor in
starch, but no evident wet rot develops from them.
Microscopic examination shows that the protoplasmic contents,
of the cells in the injured areas are diseased and discolored red-
dish-brown. Often this gives an appearance as if the plasmodium
of some extraneous organism were present. No evidence of
fungous threads or bacteria was detected. Attempted cultures
made from the diseased tissues uniformly gave no growth of any
'kind, except in a few cases where outside contamination had
occurred. Similar cultural attempts made by the writer (I) in
Illinois some years ago, likewise indicated that the trouble was
not of a parasitic nature, and Stewart of New York also failed
to obtain any parasitic organism from the diseased tubers. All
of the investigators in this country agree in considering it a
physiological trouble, and to the writer it appears to be very
much like the Baldwin Spot of apples. -
Poor soil, dry weather, lack of potash or lime, susceptibility of
certain varieties, etc., all have been assigned as probable or partial
causes. In this state last year the drought was certainly severe,
but so far as observed by the writer, the trouble was conspicuous
only in varieties poor in starch. Stewart (6), v/ho made a study
of the disease in New York in 1895, showed that it was not prop-
NOTES ON FUNGOUS DISEASES FOR I907. 357
abated by diseased tubers, and others have had similar results.
The trouble was particularly prominent in this country about
1893-95, as it was then reported by the writer (i) in Illinois,
Green (2) in Minnesota, Stewart (6) in New York, and the
United States Department of Agriculture. It seems to be com-
mon in Europe, and according to Jones (4), it is not generally
regarded there as a parasitic trouble. Sutton (7) notes its
presence in England, where it is very likely to occur on light
loams or sandy soils, when twenty to seventy per cent, of the
tubers may be diseased. Helms (3) reported its presence in
Australia in 1895. The following are the references to this
trouble that have been alluded to here:
1. Clinton, G, P. Interior Spotting. 111. Agr. Exp. Stat. Bull. 40:
138-9. 1895.
2. Green, S. B. Internal Brown Rot of Potatoes. Minn. Agr. Exp.
Stat. Bull. 39 : 212-3. Ibid., 45 : 310. 1895.
3. Helms, R. Report on an Investigation into the Potato Diseases
prevalent in the Clarence River District. Agr. Gaz. N. S. Wales
6: 328. 1895.
4. Jones, L. R. Internal Brown Spot. U. S. Dep. Agr. Bur. PI. Ind.
Bull. 87: 12-13. 1905-
5. Morse, W. J. Internal Brown Spot of the Tuber. Me. Agr. Exp.
Stat. Bull. 149: 318-21. 1907.
6. Stewart, F. C. Internal Browning of Potatoes. N. Y. Agr. Exp.
Stat. Bull. loi : 78-82. 1896.
7. Sutton, A. W. Internal Disease. Journ. Roy. Agr. Soc. Engl., Ill, 9:
599-600. 1898.
ScuRF^ Spondylocladium atrovirens Harz. Plate XXIII, b-d.
In the spring of 1907 this potato disease was first called to my
attention by Mr. East, who noticed it on a few tubers among the
many varieties to be tested that year by the station. It was also
found not uncommon that fall on a still larger number of these
same varieties. While not a serious potato trouble, it is interesting
because it has not before been reported in this country. It has
been known for some time in Europe, and apparently was intro-
duced into Connecticut on imported varieties. On unwashed
tubers the trouble does not show very plainly, but on perfectly
clean ones it appears as a slightly sunken area, of greater or
less extent, which has a darker brown color. It is not nearly so
conspicuous or injurious as scab, though it finally causes the
tubers to shrink somewhat over the affected areas, and may offer
entrance for decay germs.
35^ CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
The fungus that causes this trouble is usually evident, when
tubers are kept for a time in a moist chamber, as a scanty growth
of short, upright, blackish bristles, easily seen with a lens. These
are the conidiophores, and bear irregular whorls of spores on
their upper end (see illustration, Plate XXIII, c). The conidio-
phores are dark reddish-brown, often with a slightly swollen
base, and taper somewhat toward their free extremity. They
are septate (6 — i6 septa), and vary in length from i6o — 425jw.,
and in width from 6 — 127*. While stiff, and generally erect,
they are sometimes somewhat bent or kneed, and rarely branched
toward their base. They arise singly, or more than one, from
a knot of fungous cells which infest the epidermal cells. The
spores are reddish or greyish, but lighter colored than the coni-
diophores, and easily fall from them. They vary from oval
to chiefly obclavate, and are 4 — 8, usually 6, celled. They are
fastened to the conidiophore by the broader end, and are usually
acute at the apex, but will occasionally be rounded at both ends.
On falling off, they generally show the point of attachment as an
evident dark ring at their base. They vary from 23 — 52 /a, chiefly
30 — 40 /A in length, and from 6 — 9 /a in greatest width. In
germination they put forth a single tube at the pointed end.
This fungus was apparently first found and described in
Vienna, Austria, by Harz, in 1871 (Einige Neue Hyphomyceten :
129-30), Frank, in 1897 (Kampfbuch gegen die Schadlinge unsere
Feldfriichte) and again in 1898 (Ber. Deut. Bot. Ges. 16: 280-1)
called attention to a new sterile fungus, named Phellomyces scler-
otiophorus, which formed very minute dark colored sclerotia in
the epidermal cells, and which he held responsible for a sort
of dry rot of potatoes under some conditions. Johnson (Econ.
Proc. Roy. Soc. Dublin i : 161-6. 1903) and Smith and Rea
(Trans. Brit. Myc. Soc. 1903-04: 59-67) have also called
attention to this Phellomyces causing injury to potatoes in Great
Britain. In 1905 Appel and Laubert (Ber. Deut. Bot. Ges. 27,:
218-20) succeeded in getting these sterile sclerotia to produce a
fruiting stage which they recognized to be the Spondylocladium
atrovirens of Harz. In 1907 they gave a further account of the
fungus in Arb. Kaiserl. Biol. Anst. Land. Fortw. 5: 435-41.
In some of the specimens which we have seen, very small black-
ish spots or "sclerotia" occurred on the surface of the tubers apart
NOTES ON FUNGOUS DISEASES FOR I907. 359
from and with the fruiting stage of the Spondylocladium ; these
we have considered to be the Phellomyces sclerotiophorus of
Frank. These sclerotia are composed of compacted colored cells
of the fungus, which more or less completely fill the epidermal
cells (see Plate XXIII, d). The mycelium of the fungus evidently
at first does not penetrate very deeply .into the tissues, and so
forms only a superficial injury.
Saccardo (Syll. Fung. lo: 662) describes another species of
Spondylocladium, S. ahietinum (Zuk.) Sacc. on potato tubers,
also from Vienna, Austria, that very probably is the same as
this, though the spores are said to be only 3 — 4 septate, but
are 38 by 9/*. The spores of our specimens are smaller than
the measurements given by Appel and Laubert for 5. atrovirens,
but agree in the number of septa, while they agree in size with
the other species, but not in the number of septa. Specimens were
sent to Appel, who states that he is not yet sure whether these
two species are distinct or not, though there seem to be at least
two forms, one having larger spores than the other. If the
species are distinct, our specimens apparently belong to the
smaller spored species.
ROSE, Rosa sp.
RusT^ Phragmidium speciosum Fr. Sturgis, in his Report for
1893, p. 86, mentioned injury to cultivated roses by another species
of rust, P. suhcorticium, but this is the first note in the station's
Reports of the above species. It was found on cultivated roses in
Westville, causing considerable injury to the stems, to which it
was limited. As usual, only the III stage appeared on the
infected stems, forming small, hard, black pustules, usijally
occurring in clusters.
SWEET PEA, Lathyrus odoratus.
Dampening Off, Pythium sp., Rhisoctonia sp. During last
July, when sweet peas were about one-third to one-half grown,
occasional vines showed evidence of trouble by turning yellowish,
wilting, and finally drying up entirely. An examination of such
plants .showed that they were more or less separated from their
roots near the surface of the ground by a reddish-brown rot.
Microscopic examination of the injured tissues revealed the
360 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
presence of one or the other of the above fungi as the cause of
injury. Although the trouble was quite common, usually enough
plants escaped to make a fair stand. As manure encourages the
growth of such fungi, it should be used with care, especially at
the surface of the ground. The cold, backward spring was
apparently largely responsible for the unusual amount of dampen-
ing off this year.
SYCAMOEE, Platanns occidentalis.
, Frost Injury. One or both of the severe frosts of May ii and
21 severely injured the unfolding leaves of the sycamore trees
throughout the state, so that practically all of those out of the
buds were killed outright. The injury was evident immediately
afterward, but became even more conspicuous later, when the
remaining leaves began to assume some size, through the very
scanty foliage, which in many cases was confined entirely to the
tops of the trees. While some trees had all their leaves killed,
and so were destitute of foliage for a time, most of them finally
put forth about one-fourth to one-half the normal foliage, but
even then the injury was evident all summer. This injury to the
sycamore was not limited to this state, since von Schrenk (Rept.
Mo. Bot. Gard. 1907: 81-3) has pubHshed a short article in
which he calls attention to similar injury extending from the
Mississippi Valley eastward. The writer did not notice any
serious damage to the leaves of other trees, but probably the
sycamore leaves were the only ones just in the right condition
for such an injury when the frosts came. Murrill (Journ. N. Y.
Bot. Gard. 8: 157-61. Jl. 1907), Lloyd (Plant World 10: 213.
S. I807) and Halsted (Ann. Rep. N.J. Agr. Exp. Stat. 1907: 381.
1908) have made the mistake of attributing this trouble to the
fungus Gloeosporium nervisequum, which frequently injures
the foliage of sycamores.
TOBACCO, Nicotiana Tabacum.
Sumatra Disease, fBacterial. Shamel has previously called
attention to this trouble in Bulletin 150 of this station. The
seed from which the Sumatra tobacco was grown was imported
by the United States government a few years ago. Last June Mr.
Shamel showed the writer a small experimental seed bed at
NOTES ON FUNGOUS DISEASES FOR IQO/. 36 1
Granby in which most of the plants had been killed by this
disease; the surviving plants had ceased to grow, at least for
the time, and a few that were transferred to crocks in the
greenhouse never made any further growth. The injury was
not exactly like either the dampening off troubles or the root
rot disease. So far as could be determined from this bed, the
disease started in the roots, and was most manifest in the vicinity
of the bundles, up which it developed a short distance above
ground. The roots and the base of the stem, in time, were so
severely injured that most of the plants succumbed. Those alive
usually showed the lower leaves, with a sickly, yellowish color,
and within their tissues was sometimes found a Pythium-like
fungus, which was apparently an after-comer. The disease
appears, on the whole, like a bacterial trouble of the bundles,
but specimens of the older plants were not seen to throw further
light on the subject.
Concerning this trouble in the field, Mr. Shamel in his bulletin
says : "A field was set out with plants grown from imported
seed, which were attacked by a fungous root disease and all died
with the exception of a few plants. These resistant or immune
.plants were found irregularly over the field, and produced ripe
tobacco of excellent quality. All the other plants were com-
pletely destroyed, with the exception of one or two semi-resistant
plants that produced a large amount of seed, but very few and
extremely small leaves. The seed was saved separately from
the resistant and semi-resistant plants, and sowed in separate
sections of the seed beds. The resistant seeds produced perfectly
resistant plants, both in the seed bed and in the field where the
plants were destroyed the previous year. Most of the seedlings
from the semi-resistant seed died in the seed bed. Enough were
finally secured to set out one or two rows in the field. These
plants grew slowly, some died, and none reached maturity, all
having the characteristics of the diseased plants in roots, stem and
leaves. Some of the resistant seed was sown on the seed bed
where the diseased seedlings had been destroyed, and this immune
seed produced perfectly resistant plants under these circum-
stances."
Mr. Shamel seems to think that our native varieties are not
subject to this trouble, and so far it has not been found on them.
362 CONNECTICUT EXPERIMENT STATION REPORT^ I907-I908.
Stevens (N. C. Exp. Stat. Bull. i88. 1903), however, has
described a bacterial wilt of tobacco from North Carolina that
possibly may prove to be the same as this. Uyeda also has
described a similar bacterial trouble from Japan, and Delacroix
from France. All of these, however, describe it as a field disease,
and little or no mention is made of its injury in the seed bed.
TOMATO, Lycopersicum esculentum.
Chlorosis. Last fall in Westville the writer saw a large field
of tomatoes in which many of the plants showed leaves more or
less mottled with yellowish-green. This unhealthy coloring was
quite similar to the injury that can be transferred to tomatoes
from calicoed tobacco. On inquiry, it was found that the tomatoes
had been severely injured by the late frosts of May, but had
finally recovered and had borne a fair crop. It looked to
the writer as if this chlorosis of the plant was one of the after
effects of the frost, and was of the nature of the so-called calicoed
tobacco, but whether or not it was infectious through the juice
of the injured plant was not determined. Woods claims that a
similar trouble in tomatoes can be produced by a very severe
pruning back of the vines, and possibly the frost injury was in
effect merely such a pruning.
TKTJMPET CREEPER, Tecoma radicans.
Leaf Blight, Cercospora sordida Sacc. This fungus shows
on the under surface of the leaves as small, angular, olive-brown
patches, either distinct or more or less run together. The spore
stage which forms these patches consists of short, dark, olive-
brown conidiophores bearing lighter colored spores. The spores
vary from linear to linear-obclavate, are smoky tinted, 4 — 12
septate, straight or somewhat curved, and range in size from
40 — 120/U, by 2.5 — 5.5/^- The injury to the leaf first shows
on the upper surface as a yellowish discoloration which in time
may change to reddish-brown, but ordinarily it is not very
severe. Two other species of Cercospora have been described
from the United States on this same host, but it is doubtful if
all three are distinct.
ROOT ROT OF TOBACCO. 363
II. ROOT ROT OF TOBACCO— II.
In the Report for 1906 the writer gave a somewhat extended
account of the fungus Thielavia hasicola (B. & Br.) Zopf, and
the injury it caused to cultivated plants, especially to the tobacco
in Connecticut. In this article is added such additional informa-
tion as came to hand during the past season, when the investiga-
tion was brought to a close. Dr. E. A. Bessey, of the Govern-
ment's Subtropical Laboratory in Florida, writes that he has
found this fungus on the roots of tobacco sent from Cuba, on
cultivated violets from the District of Columbia, on the garden
pea in South Carolina, on sugar beets from Utah, and on various
plants in Florida. Galloway, in his book on violet culture, also
reports it as a serious pest on violet roots. No doubt, it is a com-
mon and widely distributed soil fungus, at least much more so
than reports have hitherto indicated.
Cultures. During the past year and a half the fungus has
been under observation in cultures with various media in an
attempt to develop the ascospore stage. This has not been
obtained, though the fungus was grown on tobacco roots on
which this stage occurs in nature in Connecticut. Fresh tobacco
roots containing the fungus were sent to Professor Thaxter,
who tried to isolate the ascospores by the Barber method, and
obtain cultures directly from them — our cultures having come
originally from the endospores, or possibly from the chlamy-
dospores — but he was not successful in obtaining such cultures.
Professor Thaxter has, on the other hand, a culture of another
species of Thielavia which forms the ascospores, but never the
endospores and chlamydospores. These facts possibly may indicate
that the ascospore stage has no relationship to our fungus, and
that it occurs on the tobacco roots as a parasite of the fungus
rather than as a stage of it. However, the mature stage of certain
other fungi, the apple scab, for example, is rarely, if ever,
obtained in artificial cultures, while the other stages readily grow
there. For the present it is perhaps best to consider the ascospore
form as the mature stage of the fungus with the under-
standing that further study is needed to positively prove this
connection.
364 CONNECTICUT EXPERIMENT STATION REPORT^ I9O7-I908.
Seed beds. There was more or less complaint of the root
rot in the tobacco seed beds the past spring, especially in the
neighborhood of Granby. Some growers lost their beds, and
others gave them up because of previous injury, and made new
ones. Where it can be done conveniently, this is perhaps the
wisest thing to do. If it is of advantage to retain the old beds,
our experiments have shown that they can be treated successfully
with either formalin or steam, and the injury will be largely or
entirely prevented.
Several beds were treated with formalin last fall and spring,
all of which showed that the treatment had done no harm, and in
most of them some benefit resulted even when the root rot or the
dampening off troubles were not present to any injurious extent
in the check beds. The two beds at Bridgewater, mentioned in
our last Report, p. 329, which were treated in the fall of 1906 for
the stem rot, did not give a fair idea of how effective this treat-
ment would prove for this trouble, since no serious injury from
the stem rot developed in the treated or untreated parts of the
beds the next spring. In both cases, however, the plants upon
the treated parts were a little more advanced than those on the
untreated, and there were also fewer weeds and angle worms
in them. In a bed treated for root rot at Poquonock in the fall,
the soil had been covered with a layer of sand two or three
inches deep just before the treatment, and this apparently inter-
fered somewhat with the full action of the formalin on the
infested soil beneath, since a little root rot was found the next
spring in the treated part, though not as much as in the untreated.
The injury in either case, however, was not severe, the sand
apparently, when spaded in, having helped the mechanical char-
acter of the soil, or in some other way prevented as serious
injury to the tobacco from the fungus as had occurred the year
before.
The most extended experiments were made by the Director
and the writer in a bed grown especially for the station by Mr.
E. S. Hale of Portland, and upon these we report more in
detail. This bed, which was one that had been injured consid-
erably by the root rot the year before, was ninety-one feet long
by six feet wide. In the fall, before treatment, it had been
manured and tilled in the usual way, and in the spring such com-
ROOT ROT OF TOBACCO. 365
mercial fertilizers as were needed were used. It was sown with
sprouted tobacco seed April 25, covered with cloth, and watered
as needed. The only difference in the treatment of the various
plots into which the bed was divided was as follows :
(i) In the fall, November 9th, a twenty- five foot plot vi^as treated with
formalin, strength i to 100 water, this being sprinkled on at the rate of one
gallon to each square foot.
(2) In the fall a seventeen foot plot was treated with steam by means
of a steam rake whose teeth were pushed about eight inches into the soil.
The rake was wide enough to take in the width of the bed, and two
lengths made the seventeen feet. The rake was covered with sacks and
boards to hold in the steam. The treatment with the first length was made
for two and three-quarter hours, because of some difficulty with the
steam. At the end of the treatment tests of the temperature of the soil
midway between the teeth showed an average at two inches of 96° C,
at four inches of 99° C, at eight inches, 97° C, and at ten inches,
82° C. Between the rake and the boards on the outside of the bed the
temperature was not nearly so high. The second treatment was made
only for one and one-half hours, and probably the temperature did not
reach quite so high, but no difference in the plants was noticed on this
account.
(3) In the fall a nine foot plot was treated with formalin, strength
I to 200 of water, using one gallon to each square foot.
(4) In the spring, April i6th, a fourteen foot plot was treated with
formalin, strength i to loo, using two-thirds of a gallon to each square
foot.
(5) After the plants were up, a ten foot plot was sprinkled with weak
formalin water, about i to 1000 or 1200, nine times (May 3, 15, 22, June i,
8, 12, 15, 20, 25) instead of being watered, as was the rest of the bed on
those dates.
(6) A sixteen foot plot was reserved as a check; that is, it had no
unusual treatment.
The final results of these treatments, in general, were as
follows :
(a) The steam heated plot (No. 2) produced the best stand,
with plants most advanced, though at the time for pulling it
had lost much of this lead over the formalin treated plot (No. i),
which was next best, and had a fine stand of plants. The formalin
treated plots (Nos. 3 and 4), though somewhat behind plots 2
and I, produced a good lot of plants. The formalin sprinkled
plot (No. 5) and the check or untreated plot (No. 6) were both
about the same, and made a very poor stand and groivth. The
contrast between these two poorest plots and the two best at
pulling time is shown by the illustrations in Plate XXIV.
366 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
(b) Sprinkling zuith weak formalin (plot 5) evidently injured
the plants, as the stand was very uneven, and the plants small
at pulling time. This was possibly due to the large number of
treatments, and began to show about the time of the third treat-
ment, though by accident the first was about twice as strong as
the others. Apparently the sprinkling method is not of much
value.
(c) The steam treatment very materially reduced the number
of weeds, and apparently the formalin treatment had somewhat
similar effect. The formalin and steam both killed the angle
worms, and the latter, undoubtedly, wire worms, insects, etc.
The total number of weeds taken from each plot and the rate
per square foot for each was as follows: Plot No. i, 11 59, a
rate of 8 per square foot; plot No. 2, 104, or a rate of i per
square foot; plot No. 3, 606, or a rate of 11 per square foot;
plot No. 4, 388, or a rate of 5 per square foot; plot No. 5, 885,
or a rate of 15 per square foot; plot No. 6, 3188, or a rate of 33
per square foot. The rate of the last two was raised considerably
by the poor growth of the tobacco, which thus failed to crowd
out the weeds; in plot 5, this may have been offset by injury
to the weeds from the formalin.
(d) The untreated plot (No. 6) had considerable root rot in
it, but this was not so severe as to entirely rot off the roots of
many of the plants, since these usually retained a firm hold on
the ground. In the formalin plots (Nos. i, 3, 4) and the steam
heated plot (No. 2) only a very little root rot was finally found,
not enough to cause any harm whatever.
(e) We do not believe that the marked difference between
these steam and formalin treated plots and the untreated plot
was entirely due to the prevention of the root rot, as this did
not seem so prominent as to have caused this difference. It is
possible that part of the difference was due to a disturbance of the
bacterial flora of the soil, in favor of the species more beneficial
to plant growth, such as has been reported in Europe in the
treatment of the soil of vineyards with carbon bisulphide.
Conclusions. From all of the experiments we have made
during the past two years, we believe that the formalin treatment
is a very efficient and convenient method of protecting tobacco
beds against the root rot and possibly the dampening off trouble.
ROOT ROT OF TOBACCO. 367
The formalin is best applied in the fall, after the beds are pre-
pared for seeding-, but may also be used early in the spring, if
the beds are thoroughly aired afterwards. Formalin, 40 per cent,
strength, used at the rate of i to 100 of water, should be
gradually sprinkled on the beds, using about one gallon to each
square foot of surface treated. The bed should then be covered
for a day or two to keep in the fumes. The steam treatment is
fully as effective against the root rot, and even more efficient in
kilhng weed seeds, but is more cumbersome and expensive,
especially if the necessary apparatus is not at hand. The soil in
this case should be steamed for at least an hour after the appa-
ratus is in good running order.
In the fields. The drought of the past summer had consid-
erable effect on the growth of tobacco at that time, but the moist
weather coming toward the end of August helped many of the'
fields to partially recover. Because of the drought the root rot
fungus apparently was not so conspicuous in the fields as last year,
though no doubt the injury it did cause was more or less obscured
by the injury from the drought. As in the previous year, the
tobacco in the region of Suffield, especially in certain fields, suf-
fered severely from root rot or some other cause. From our
examinations there, we are more convinced than before that the
trouble is not alone caused by the root rot fungus, though this
is the only agent of injury that we can be sure of so far. It
is very probable, however, that in the worst affected fields such
matters as fertilizers, drainage, poisoning of the land through
continued use for tobacco, may have had as much or more to do
with the failure of the crop than this fungus.
Our crock experiments (see Report of 1906, p. 362) with
fertilizers, etc., in soil from two fields in Suffield that gave very
poor crops in 1906, did not throw very much light on the subject
except that those crocks treated with formalin gave by far the
best plants all through the test. At first the best plants in all
the crocks were apparently those whose roots were freest from
'root rot, but the single plants finally left in each crock at the
end of the experiment did not show so much difference in the
amount of fungus on their roots as they did in their vigor of
growth. We have noticed in the fields, too, that it is often
difficult to entirely explain the dift'erence in size of individual
368 CONNECTICUT EXPERIMENT STATION REPORT^ I907-I908.
mature plants by the amount of fungus on their roots. However,
this possibly may be explained by the fact that the injury which
counts most is that given to the young plant when some main
or tap root is rotted off and thus stunts the growth, at least for
the time, rather than a general, but not so severe, injury distri-
buted over the root system, and which in mature plants might
show as conspicuously as in the other case, so far as the total
amount of root rot is concerned.
No field experiments were conducted directly by this station,
but the writer had the privilege of seeing those made under
Mr. Shamel's directions at Suffield with various fertilizers, etc.
While there was some slight difference between these plots
(most prominent in the plot where the ground had been treated
with formalin, and in one of the fertilized plots), there did not
■seem to be sufficient difference to indicate any practical way
of successfully treating infected fields. These plots were part
of a field that had been in tobacco before, and the rows con-
tinued onto land that was new, or at least, not in tobacco the
year before. The difference in the size of the tobacco on the
new and the old land, in favor of the new land, was the striking
thing to be seen here, rather than that due to any difference in
the treatment. In other instances that we have known, the
tobacco on the new land seemed to do much better than that
on the adjacent old land.
Conclusions. There seems to be, so far as now known, no
effective treatment for a field in which the tobacco has been
gradually going backward in spite of good care. In such a
case the best thing is rotation for a year or two. Of course,
on many farms the land available for tobacco is no more than
is needed, and this is one of the reasons why rotation is not more
commonly practiced. In such instances the amount of injury
the crop suffers will determine whether or not the farmer can
afford to use this land for other purposes. We saw one field
last year, however, where there was no question but that the
owner would have saved money if he had not used it at all, and
no doubt there were other cases of the same sort.
HETEROECIOUS RUSTS. 369
III. HETEROECIOUS RUSTS OF CONNECTICUT
HAVING A PERIDERMIUM FOR THEIR
AECIAL STAGE.
GENERAL CHARACTER OF RUSTS.
Appearance. Rusts are among the most common and widely
distributed forms of parasitic fungi. While it is difficult to
describe their general appearance so that one unacquainted with
the rusts can readily distinguish them from other fungi, still
they do possess characters by which the expert readily recognizes
these fungi with the naked eye. Perhaps to mention such com-
mon forms as the grain, asparagus, and chrysanthemum rusts,
the cluster-cup of apple, and the cedar-apples of red cedar, is
one of the best ways to describe them. In appearance they more
nearly resemble the smuts than any other fungi, and in some
cases are easily confused with these. In general their outbreaks
occur scattered or clustered on the leaves or stems of plants
(hosts), forming small roundish or linear spore clusters or sori.
These sori, as a rule, are less dusty and more highly colored than
the smuts. Early in the season the rusts often have a reddish,
and later, a blackish color, as seen in the grain and asparagus
rusts, due to the production of different stages.
Stages. The rusts are fungi that usually have more than
one spore stage, in some cases having four different forms. The
earliest stage, called the pycniwn (O, spermagonium), is the
most inconspicuous, and the one about which the least is known,
for botanists are not yet certain whether it is a spore stage
or the male element in sexual reproduction, and whether in either
case it is now functional. It is generally associated with the next
stage, often occurring on the upper side of the leaf, while the
latter occurs on the lower, and is usually distinguished as
minute blackish specks situated on discolored spots. (Plates
XXVI, b; XXX, a.) The next, and generally considered the
first spore stage, is called the aecium (I, aecidium, etc.). This
usually has a distinct covering or cup-like receptacle called the
peridhmi, which, when it opens, becomes toothed, fringed, or
irregularly worn away, disclosing the enclosed mass of yellowish
or orange-colored spores. The peridia in different species vary
27
37° CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
from the size of a small pinhead up to about one-third of an
inch in diameter. (Plates XXVI ; XXVIII, a-b.) The next stage,
known as the uredinium (II, uredo-stage), usually forms numer-
ous, small, naked outbreaks of reddish-brown spore' masses on
the surface of the leaves, etc. (Plates XXVII, a; XXVIII, c;
XXIX, b.) It is the stage most commonly seen, as its function is
to spread the fungus over the infected plants and to new ones.
The last stage, called the teli-um (III, teleuto-stage), is usually
formed late in the season, and is the one that generally carries
the fungus over the winter, so it is considered the mature stage.
(Plates XXVII, b; XXVIII, d; XXIX, c.) The sori in this
case may be developed externally on the plants or be imbedded
in their tissues, and so the spores do not always form a dusty
mass to be easily scattered, as in the uredinial stage. With the
germination of the telial spores (usually forming in this process
very temporary thin-walled secondary spores called sporidia) the
rust may start anew the cycle of its life history on successfully
infecting its proper host.
Heteroecism. It will be seen from the preceding account that
rusts possess, in some cases, a complicated life history. The I,
II and III stages are so different that they were considered by the
early botanists as distinct genera (now known as form genera),
and so they were frequently described under different specific
names. When the life history of a rust is fully determined, all
of its stages are then united under one name, the generic name
being decided by its telial form. The relationships of the rusts
are further complicated by the fact that, with some species,
certain of their stages may occur on one plant and the others
on an entirely different plant. This is known as heteroecism.
In such cases there is no general rule by which a person can
definitely determine what hosts the different stages will occupy,
though investigations are throwing considerable light on this
matter. Therefore the life history of each species must be worked
out by itself. Clues to the alternate host often may be obtained
by closely watching the fungus in nature and determining what
other related rusts with their hosts occur in the neighborhood
of the one under observation. For instance, the farmers of
England years ago noticed that the wheat rust was worst in
the neighborhood of barberries having the cluster-cup rust; and
from this clue De Bary, the great German mycologist, by infection
HETEROECIOUS RUSTS. 37 1
experiments on these two hosts was the first to prove definitely
their relationship and the phenomenon of heteroecism.
Kinds of aecia and their relationship. With the heteroecious
rusts usually the O and I stages occur on one host and the II and
III on the alternate host. The use of the I stage is to carry
the fungus to the second host, that of the II stage to spread
it on this host, while the III stage carries it back to the first,
usually early the next year. Now, the I stage, or aecium, may
have the spores without a peridium (when it comes under the
form genus Caeoma) ; the peridium may have the margin merely
toothed (Aecidium) ; its margin may be more or less decidedly
fringed (Roestelia) ; or the fragile peridium may break up
rather indefinitely (Peridermium). The Caeomae species are
not very common in this country, and their relationships have in
but few cases been definitely worked out. From the investiga-
tions that have been made in Europe one may expect that most
of them are stages of the Melampsora-like rusts. The species
of the Aecidia are very numerous, and the American heteroecious
forms have been found by Arthur and Kellerman to belong
chiefly to the Pucciniae and Uromyces that inhabit grass-like
plants. The American species of Roesteliae, which occur only
on rosaceous hosts, through the studies of Farlow, Thaxter,
Arthur and Kern, are now very completely connected with the
species of Gymnosporangia, which occur only on cedar-like hosts.
Relationships of the P eridermia. The Peridermia, some thirty
odd species of which Arthur and Kern (5) have described in
their recent American monograph, limit their attacks to coniferous
hosts. In this form genus the peridia generally extend promi-
nently above the tissues of the host, the walls are white, very
fragile, and separate in a rather indefinite fashion upon the
wearing away of the aecia. All Peridermia, apparently, belong
to heteroecious rusts, but so far the relationship of less than a
dozen American ones to their telial stage is known. Added
interest is given to the Peridermia because they are the aecial
stages of at least seven telial genera, as now understood, namely,
Calyptospora, Coleosporium, Cronartium, Melampsorella, Me-
lampsoridium, Melampsoropsis, Pucciniastrum, and possibly
Necium and Kuehneola (in case of K. alhida). It is with the
Connecticut species of these telial genera and their known or
possible Peridermia that we are to deal especially in the present
372 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
paper. So far, in America, Shear (i6) has shown that Perider-
miuni cerebrum on trunks of Pinus sps. belongs to Cronartium
Quercus on Quercus sps.; Kellerman (13), that Peridermium
Rostriipi on leaves of Pinus rigida is connected with Coleospo-
rium Campanulae on Campanula sps. ; and the writer (6, 7), that
Peridermium acicolum on Pinus rigida belongs to Coleosporium
Solidaginis on Solidago, etc., Peridermium pyriforme on trunks of
Pinus sps. to Cronartium Comptoniae on Comptonia asplenifolia,
and Peridermium consimile on leaves of Picea nigra to Melamp-
soropsis Cassandrae on Cassandra calyculata. The probable rela-
tionship of several of our other species is known through the
work of European investigators, especially that of Klebahn.
Farlow (9, 10) and others have suggested possible relationships
of still other species.
Injury. While rusts in general are among the most injurious
fungi, the forms discussed here are none of them very serious
pests, at least in Connecticut. In Europe more or less complaint
has been made of certain of the Peridermia attacking forest trees.
Stone, a few years ago, recorded injury to blackberries in Massa-
chusetts by Kuehneola alhida, so far found here only once on
cultivated blackberries. The rust on the leaves of the pitch
pine was very common in a forest reserved for landscape effect
at South Manchester, and caused the owner some uneasiness lest
it become of more serious trouble. A rust which was found on
the trunks of the Scotch pine in the state plantation also would
become a serious pest if more abundant, since its injury to the
young tree is very considerable. While one or the other of
the hosts of all of the forms discussed here are of some
economic importance, so far the injury to them by their rusts
has not been such as to attract any considerable attention. It is
not, therefore, because we consider these rusts at present of
great economic importance in the state that we have made a
special study of them, but rather because of their very interesting
problems of heteroecism and a desire to solve more completely
their life histories and to awaken a more general interest in them.
Classification. Because of their variable number of stages and
of the heteroecism of certain species, the classification of the rusts
is more difficult than that of most fungi, and gives a basis for hon-
est differences of opinion among investigators. Some botanists lay
more stress on the host than others, thus greatly multiplying the
HETEROECIOUS RUSTS. 373
number of species. A further source of trouble arises from the
fact that morphologically similar rusts often infect entirely-
different, though closely related hosts, as proved by infection
experiments. This gives rise to further confusion, since some
botanists consider such rusts as distinct species, while others
classify them as physiological species, or consider them merely
as strains. These differences of opinion cause a grouping together
of species and genera on the one hand, or to their splitting up on
the other, according to the attitude of the investigator. In this
paper we have used the nomenclature of Arthur (2), as given
in his recent monograph, because he has made the most extended
and thorough study of our American rusts ; and, to avoid
unnecessary confusion, we prefer to follow his work until fur-
ther investigations shall have more definitely determined the
nomenclature and relationships of the forms discussed.
Species considered. As stated before, we deal here only with
Connecticut rusts supposed to have a Peridermium for their
aecial stage. So far only four species of Peridermium {P. acic-
oluni, P. pyriforme, P. consimile, P. Peckii, Plate XXXII, i)
have actually been found in the state. It is quite probable that
other species exist here, since the search has extended only over
a period of two years, and has not been made in the northwestern
part of the state, where these species probably occur most
abundantly. From their hosts and distribution, other species
likely to occur here are P. Rostrupi on leaves of Pinus rigida,
P. Laricis on leaves of Larix sps., P. cerebrum and P. glohosiim
on branches of Pinus rigida, P. globosum and P. Strobi on
branches of Pinus Strobus, P. conorum-Piceae on cones of Picea
nigra, P. elatinum, which forms witches' brooms, and P. bal-
sameum, which does not, on leaves of Abies balsamea. On the
other hand, the uredinial or telial stages of thirteen species have
been found in this state, namely, Coleosporium Campanulae, C.
Solidaginis, C. Vernoniae, Cronartium Comptoniae, Kuehneola
(Chrysomyxa) albida, Melampsoridium Betulae, Melampsoropsis
Cassandrae, M. Pyrolae, Neciuni Farlowii, Pucciniastrum Agri-
moniae, P. minimum, P. pustulatum, P. Pyrolae. Besides these
there are six to ten other species that possibly may be found
here in time. See list at end of this article. A special discussion
of those already found here follows.
374 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
SPECIAL DISCUSSION OF CONNECTICUT SPECIES.
I. Coleosporium Campanulae (Pers.) Lev. (I. P eridermium
Rostrupi E. Fisch.)
I. Plate XXV, a, (from Ohio Fungi 104). The aecial stage
of this fungus has not yet been found in Connecticut. The fact
that it occurs on the same host as P eridermium acicoliim and is
scarcely to be distinguished from the latter may indicate that it
has been confused with this species. While the relationship
between a Peridermium on pine leaves and a Coleosporium on
Campanula was first shown by European investigators, Kellerman
(13) was the first in this country to produce Coleosporium Cam-
panulae from a Peridermium on Pinus rigida, collected in Ohio.
Arthur arid Kern (5, p. 416) later called the aecial stage Perider-
mium Rostrupi, after the European form, though previously it
had not been considered distinct from our common P. acicolum.
II, III. Plate XXV, b-c. These stages have been found in
Connecticut only once, in October, 1907, on Campanula rapuncu-
loides growing in a nursery at Westville. The II s^tage was
common on the leaves, causing some injury, and the owner stated
that he had noticed the rust on these plants for a few years past.
The writer did not find the III stage on the plants outdoors, but
it appeared later, after some of them were removed to the
greenhouse for further observation. By the end of November
the outdoor plants were entirely dead above ground. This shows
that the fungus did not carry over the winter through the imma-
ture uredinia on the leaves, which in some plants escape winter
injury. The III stage, of course, with all heteroecious rusts, is of
use only in carrying the fungus to the alternate host, in this
case, the leaves of Pinus rigida. There was little likelihood, how-
ever, that the Peridermium occurred on the pine trees in this
vicinity, since these were watched rather closely without finding
it. The question, then, as to how the fungus passes the winter
and again appears on the Campanula is interesting. Of course
it is barely possible that this is accomplished through an occa-
sionally undeveloped infection on the underground perennial
parts. As the uredinial stage is hardly to be distinguished from
that of the Coleosporium on Solidago, and as the uredinia of the
latter were common in this neighborhood, it occurred to the
writer that possibly the rusts on these two hosts were not
HETEROECIOUS RUSTS. 375
distinct, as supposed. The germination of the uredinial spores
of the two (Plates XXXII, 2), however, was somewhat different,
those from the Campanula sending out irregular and much more
branched germ tubes than those from the Solidago. The uredinial
spores from the Campanula, too, sown on Campanula, produced
the II stage in about eleven days, but failed to infect Solidago
rugosa and Aster sps., upon which they were also shown. A
later attempt to infect the Campanula with spores of the Coleos-
porium. from a species of Aster likewise failed. The evidence as
a whole seems to indicate that these species are distinct, and so
how Coleosporium Campanulae passes the winter in this nursery
is left unsolved.
2. Coleosporium Solidaginis (Schw.) Thuem. (I. Perider-
mium acicolum Und. & Earle.)
I. Plate XXVI. The earlier writers in Europe, and even
more recently in America, called the common forms of Perider-
mium on species of Pinus, Peridermium Pini, sometimes dis-
tinguishing the leaf form as acicola and the stem form as corticola.
Later Fuckel called the corticolous form P. Pini and the leaf form
P. ohlongisporium, and more recently a number of other Euro-
pean species have been distinguished. Arthur and Kern, in their
Peridermium paper, consider the American specimens on the
leaves of Pinus rigida, which they call P. acicolum, distinct from
the European species, P. ohlongisporium, on Pinus sylvestris,
and the writer follows their usage, though not entirely convinced
that they may not be the same. The European Peridermium was
long ago connected by Wolff with a Coleosporium on Senecio, and
the writer (6) has recently connected the American Peridermium
with a Coleosporium on Solidago. Though both rusts possess
different alternate hosts, these hosts are related, and as the
morphological characters of the various stages of th'e rusts are
so similar, it may be merely a question of physiological, rather
than true specific difference that distinguishes them. Solidago
and Aster are very uncommon genera in Europe, and Senecio is
not so common here as in Europe, while Pinus rigida is an Ameri-
can and Pinus sylvestris an European species. Thus the rusts, if
the same, would of necessity have different hosts in the two
countries.
376 ' CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
P eridermium acicolum was first called to the writer's attention
in May, 1906, by Mr. Schults, a forester in Hartford, who found
it very abundant on Pinus rigida in a private grove at South
Manchester that was being developed for landscape purposes.
The owner was afraid the rust would become a serious pest, and
so Mr. Schults asked for information concerning spraying the
trees to keep it in check. The writer advised against this, but
recommended that a search be made for its alternate host, which
at that time was not known to science, and that this, if found,
be eradicated as a means for keeping the pine rust under control.
An examination late in June, when the Peridermium on the pine
was passing its prime, showed that Coleosporium Solidaginis on
Solidago rugosa was just beginning to become prominent. This
was the only rust present that could at all be connected with the
Peridermium, and besides occurring on the above Solidago, it
was found sparingly on two or three other species. The con-
nection between the Peridermium and the Coleosporium was
very plainly indicated by the fact that the Coleosporium on the
Solidago only occurred prominently under the infected pine trees,
and as the pines were mostly young, the branches reaching to the
ground, several cases were found where infected branches inter-
locked with unusually badly infected plants of the SoHdago.
Upon our advice, these young pine trees were pruned of their
branches for a distance of two to three feet up the trunk, and
the goldenrod, especially beneath the trees, was mowed to the
ground during the season. The next year an inspection failed to
show any rust on the pines, except a small amount on one or
two very small seedlings that were overtopped by some goldenrod.
So this procedure seems to be an effectual method for control-
ling this rust. So far as was observed, the rust limited its attack to
the limbs nearest the ground, and consequently was not found on
the very large trees with no branches near their base. The
young trees most badly infected were on low ground, with an
abundance of infected goldenrod around them, so that conditions
were unusually favorable for the development of the rust on both
hosts.
Inoculation experiments in the greenhouse were made during
1906 and 1907 with spores of this Peridermium from different
sources, and on three different occasions the Coleosporium was
produced on plants of Solidago rugosa. The II stage of the
HETEROECIOUS RUSTS. 377
Coleosporium generally showed inside of two weeks after the
spores were placed on the leaves, and later in the season the III
stage appeared in two cases. In van Tieghem cell tests of the
spores their germination was never abundant, and in some cases
entirely failed, though the spores were fresh. From these obser-
vations and experiments, there can be no question but that this
Peridermium has for its alternate host in Connecticut Solidago
rugosa, and presumably other species of Solidago and Aster on
which the Coleosporium occurs. So far the attempts to infect
the other species have not succeeded; but these were made only
with one other species of Solidago and a species of Aster, and
possibly not under favorable conditions. It is possible, however,
that the Peridermium does not infect all of the hosts upon which
the Coleosporium occurs, but that some of these may have
become infected originally through the uredinial stage.
The infection of the pine leaves, so far as was determined, takes
place in spring, and if then, only through the leaves of that year's
growth. If this is correct, it is the year after infection before
the aecial stage appears, as in all the cases examined the leaves
of the present year's growth did not show the Peridermium. The
other possibilities are that infection takes place in the late fall,
or in the very early spring, before the leaves of the year appear.
The first sign of the fungus was detected early in November on
a few leaves which had fully developed pycnia, the aecia appar-
ently following the next spring. The pycnia (O, Plate XXVI, b)
are prominent, few in number, situated on a yellowish spot (not
shown in the illustration), and open by a longitudinal slit.
While Arthur and Kern (5, p. 414) list only six collections of
this Peridermium from the United States, one of which was
from Connecticut, and limit it to a small area along the Atlantic
Coast, this does not necessarily mean that the fungus is very
rare, since collections have been made from five different locali-
ties in Connecticut alone during the past two years. These were
all on the leaves of Pinus rigida, as follows : South Manchester,
May 28, June 6, June 29, 1906, May 29, 1907 ; Rowayton, June
4, 1906; Rainbow, June 15, 1907; Storrs, July. 22, 1907; Union,
August I, 1907.
II, III. Plate XXVII. On the other hand, the Coleosporium
is a very common rust, widely distributed over North America
on a large number of species of Solidago, Aster, and a few other
378 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908,
closely related genera. Arthur (2, p. 91) lists over sixty of
these hosts that have been reported so far. Even in Connecticut
the Coleosporium is much more widely and commonly distributed
than the Peridermium, as shown by the following- collections
made during the past two years : Aster cordifoUus, Poquonock,
II, July 20, III, Sept. 8, 1906; A. diffusus, S. Manchester, II,
Sept. 8, 1906; A. paniculatus, Poquonock, II, Nov. 5, 1906; A.
vimineus, New Haven, II, Nov. 26, 1907 ; Callistephus hortensis,
Kent, II, Oct. 29, 1906, Storrs, II, Sept. 30, 1907, Westville, II,
Aug. 28, 1902, II, Oct. 17, 1903, II, Oct. 25, 1905 (Britton) ;
Sericocarpus asteroides, Centerville, II, June 6, 1907; Solidago
caesia, Poquonock, II, Sept. 7, 1907; 6". canadensis. East Haven,
II, Sept. 22, 1877 (Herb. J. A. Allen), Kent, II, Sept. 29, 1906,
Poquonock, II, Sept. 8, 1906; S. juncea, Centerville, II, Sept. 25,
1907; vS*. lanceolata, S. Manchester, II, June 29, 1906; S.
puberula, Woodbridge, III, Sept. 13, 1879 (Herb. J. A. Allen) ;
5. rugosa, Centerville, II, Sept. 25, 1907, Fair Haven, II, Oct.
8, 1906, Kent, II, Sept. 29, 1906, New Haven, II, Sept. 20, 1906,
S. Manchester, II, June 29, 1906, II and III, Sept. 8, 1906,
Westville, II, Nov. 3, 1906, II, Oct. 19, 1907, West Willington,
II and HI, Sept. 28, 1907; vS'. sempervirens, New London, II,
Sept. I, 1905, Woodmont, II, Aug. 1907. Besides the preceding
hosts, Arthur (2, pp. 91-2) lists the following from this state
upon which the fungus has not been observed by the writer :
Aster novae-angliae, Solidago serotina, and 5". ulmifolia.
The data in the preceding paragraph show the second stage
to be by far the most frequent, and that this occurs more com-
monly in the fall than at any other time of the year. A micro-
scopic examination of the uredinial spores also showed that
there is a marked variation, especially as regards the abundance
and coarseness of the echinulations, on the different hosts. The
extremes in this respect are certainly as great as those which
exist between the typical uredinial spores of this and other
closely related species. Just what this variation means, we
are not prepared to state.
A very interesting question concerning the fungus is how
it passes the winter. We have seen that the first stage on the
pine has not been collected very frequently, and then only in
a limited region along the Atlantic Coast, while the stages on
the goldenrod, etc., are very widely distributed over the country,
HETEROECIOUS RUSTS. 379
and frequently collected. That the I stage is no more necessary
for the appearance of the Coleosporium than is the I stage for
wheat rust, is made certain by the frequency with which the
Coleosporium is collected in Illinois, where the Peridermium has
never been found. Since the III stage can infect only the pine,
how does the Coleosporium. carry over on the SoHdago, etc., in
regions where the Peridermium does not occur? These regions
are often too remote for infection by wind-blown spores of the
Peridermium, even if such were common enough for this method
of infection, neither is it likely, in the writer's opinion, that
such infection comes from the II stage gradually working
northward from southern regions, where it may occur the year
round.
The possibility of the mycelium of the fungus being perennial
in the plants was not borne out by a microscopic examination of
stems of infected specimens of SoUdago rugosa. Badly infested
specimens of these were also marked in the field, and after all
their parts above ground were dead, their underground root-
stocks were placed in crocks in the greenhouse. Half
a dozen plants produced from these were kept under obser-
vation for nearly a year, and no rust ever appeared on them,
so the mycelium is certainly not perennial. Of course it is
barely possible in some cases, though this experiment seemed
to show that it was not a common method, that a localized infec-
tion late in the fall might take place (by uredinial spores being
washed down to the partially developed imderground rootstocks)
and thus carry the fungus over the winter.
In the writer's opinion, however, there is no question but
that the fungus is commonly carried over the winter, in all
parts of the country, by late fall infections of the II stage on
the leaves which often occur in rosettes, especially in young
plants, at the surface of the ground. We know that when
more or less protected such leaves frequently survive the winter
in Connecticut. Asters and goldenrod that are mowed late in
the season send out great numbers of basal rosettes, and, in
the fall as late as the first of December, the II stage often occurs
as abundantly on these as at any time in the year. We have
collected the II stage on such plants in December, January,
February, March and April. Germination tests of the uredinial
spores collected late in January gave as vigorous and abundant
380 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
germinations as at any time of the year. No doubt some of these
infections occur so late that the sori are not developed until
spring, since by the first of April the mature sori found are
not numerous. One of the earliest spring infections of Coleos-
porium we have found was on April 29th, on Solidago sp. and
Sericocarpns asieroides, where the, new sori occurred only on
the lower leaves, indicating that these infections had come from
sori or mycelia wintering over on the surviving basal leaves.
3. Coleosporiiim Vernoniae B. & C.
We have never found this species in Connecticut, but Arthur
(2, p. 89) lists a specimen on Vernonia novehoracensis from this
state. It is a rather common fungus on species of Vernonia in
the Middle West, where these hosts are more common than here.
The I stage is not known, and so far, apparently, no suggestions
have been made concerning it, though the connections of related
species indicate that it is a Peridermium on the leaves of some
species of Pinus.
4. Cronartium Comptoniae Arth. (I. Peridermium
pyriforme Pk.)
I. Plate XXVIII, a-b. Ever since proving the connection
between the Peridermium on pine leaves and the Coleosporium
on Solidago, we have been on the lookout for a Peridermium
on the stems of pines to connect with the only species of Cronart-
ium (on sweet fern) that occurs in this state, since the work
of various investigators has shown that the corticolous forms
of Peridermia occurring on pine are the aecial stages of Cro-
nartia. Mr. Hawes, the state forester, gave the first clue to
the occurrence of the Peridermium on pine trunks when, on
questioning, he recalled that he had seen some fungus that
worked on certain of the pine trees in the state plantation at Rain-
bow. He agreed to watch for this fungus, and early in June,
1907, sent specimens of Pinus sylvestris that were badly infected
with a Peridermium that proved to be P. pyriforme Peck. The
writer visited the plantation June 15th and found about a dozen
trees, five or six years old, that were badly infected with the
Peridermium. These trees were in a clearing near a small grove,
but a careful search of this failed to show any rust on the
sweet fern (Comptonia as pleni folia) growing there, or the Peri-
HETEROECIOUS RUSTS. 38 1
dermium on the native trees of Pinus rigida upon which P. pyri-
forme ordinarily occurs. As the rust had been noticed at least
two or three years on the infected pines, and as they had been
grown in seed beds, a mile or two away, very close to which
the sweet fern occurred, there was no question but that they
had been infected before transplanting while very young. A
short time later the writer learned that this same Peridermium
had been found at Storrs, on native specimens of Pinus rigida,
by Mr. Graff, a botanical student, and on July 21st, through the
kindness of Dr. Blakeslee and Dr. Thom, specimens were col-
lected in this locality. On Aug. ist, specimens were also found
in the state forest at Union on the same host.
The Peridermium is perennial in the trunks of the infected
host, and does considerable injury to the young specimens,
stunting their growth, and probably, in severe cases, killing
them. In all the specimens seen, the fungus occurred only on
young trees, less than fifteen feet in height. In all of these it
was confined to the lower branches, usually next the main
trunk, and in the very young trees, to the base of the main
trunk and its branches. It caused a slight swelling, and seemed to
be confined chiefly to the bark and outer wood. When in its
prime the Peridermium is conspicuous, the peridia being much
larger than any of the other forms found here, and they are
crowded together, encircling the infected stem, and extending up
some distance upon it. The interlocking teeth or spiny processes
(see illustration, Plate XXVIII, b) that show when the peridia
break open, are also a distinguishing character. The orange
spore mass is gradually emptied, and the peridia flake away,
finally leaving few signs by which the infected trees can be
detected. This Peridermium is found from the first of June
until the last of July.
Arthur (4), in a recent paper, mentions receiving specimens of
the Peridermium from Dr. Thom of Storrs, and noting the
possible relationship to Cronartiiim Comptoniae, suggests inocu-
lation experiments by those favorably situated to prove this
relationship. Some time before, however, the writer had already
proved this connection by indoor inoculation experiments in
two different tests. In each case spores from the peridia found
on Pinus sylvestris were sown on the leaves of Comptonia
asplenifolia, and in about twelve days the uredinia began to
382 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
appear. Spores sown on species of Solidago and Quercus pro-
duced no result. Curiously enough in several germination tests
in water in van Tieghem cells, the spores failed entirely to
germinate. From our experience with the spores of the differ-
ent species of Peridermia, however, we have always found them
difficult to germinate in this way. The relationship of the
Peridermium and Cronartium was plainly indicated both at
Storrs and Union, since the infected pitch pine trees were sur-
rounded by sweet fern upon which the rust was common, while
it was not found elsewhere in the neighborhood at that time.
This, and our infection experiments, also show that the
Peridermia on the pitch and Scotch pines are the same species.
II, III. Plate XXVIII, c-d. This Cronartium has been found
along the Atlantic States from Canada to North Carolina, but
only on the. sweet fern and a related species. In this state, the
II stage begins to appear about the middle of July, while the
telial stage can be looked for about the end of August. The
uredinia show as very small, dusty, yellowish pustules on the
under surface of the leaves, while the telia are slender, reddish,
hair-like growths, more or less clustered into tufts, as shown
somewhat poorly in the illustration. So far, in Connecticut, we
have seen the Cronartium on the sweet fern only in the neigh-
borhood of infected pine trees. This, and its somewhat limited
distribution, indicate that the rust does not commonly carry over
the winter on this host, and so would depend each year on renewed
infection from the aecial stage. So far as we know, too, the
leaves of the sweet fern do not survive the winter, so that the II
stage would not be carried over on them.
This rust has been com.monly known in this country as Cronart-
ium asclepiadeum (Willd.) Fr., a species which occurs in Europe.
This is probably the correct view rather than that of Arthur,
who considers it as strictly an American species. The infection
experiments made in Europe by Klebahn and others have shown
that the aecial stage can produce the Cronartium on a number of
hosts not very closely related, one of which is an African plant
from a region in which the fungus never has been found. This
wide range of hosts, and the facts that the different stages of the
Cronartmm asclepiadeum in Europe are at least similar in
appearance to those of the American Cronartium, and that Pinus
sylvestris is a host for the aecial stage in both places, all indicate
HETEROECIOUS RUSTS. 383
the identity of the species. However, successful inoculation of
one of the European telial hosts with the American Peridermium
is needed to decide the matter finally.
5. Kuehneola alhida (Kuehn) Magn.
The above rust is commonly known under the name Chrys-
omyxa alhida Kuehn. There seems to be some doubt as to its
exact systematic position, since some botanists think that it is
more closely related to Phragmidium than to Chrysomyxa
(Melampsoropsis of Arthur). The writer inclines to the
Chrysomyxa relationship, since the telial spores are thin-walled,
colorless, and septate like those of Chrysomyxa, and the uredinial
stage is not provided with paraphyses, as are the uredinia of
Phragmidia on Rubus species. Studies were made to. determine
its first stage, so that this question could be settled more definitely,
but unfortunately the results were not conclusive. If closely
related to Chrysomyxa, the I stage no doubt is some species of
Peridermium {P. Peckii, for instance), while, if closely related
to Phragmidium, such an aecial stage is improbable, and
might be supplied, as has been suggested, by Uredo Muelleri.
We give a discussion of these two fungi before proceeding to
the known stages of the Kuehneola.
? I. Plate XXIX, a. Peridermium Peckii Thm. has for its
host Tsuga canadensis, and is apparently confined to North
America, while Kuehneola alhida has a much wider distribu-
tion. The Peridermium occurs on the under side of the leaves
in two parallel rows, one on either side of the midrib, and
forms slender, white, fragile peridia that usually split into
temporary filaments upon their dehiscence. Ordinarily this
aecial stage does not occur abundantly, usually only one infected
leaf showing on a branchlet. According to Arthur and Kern
(5, p. 434), who report only seven collections, P. Peckii has so
far been reported only from the Eastern United States. The
writer has found this species, while not usually abundant, still
not uncommon in Connecticut, the following specimens having
been collected here: Coventry Lake, July 20, 1907; Stafford
Springs, July 31, 1907; Storrs, July 22, 1907; Union, Aug. i,
1907; Westville, July, 1888 (Thaxter), July 12, 27 and 28, Aug.
4, 1907. In some of these collections only a very few infected
leaves were found, but at Storrs the fungus was very common
384 CONNECTICUT EXPERIMENT STATION REPORT^ I907-I908.
on certain trees. In practically all of the cases the leaves near
the ground were the ones infected, but on one very badly infested
tree the fungus was found as high as twenty feet from the
ground.
As soon as this Peridermium was found a search was com-
menced for the stages on the alternate host, but without find-
ing anything suspicious until at Storrs the swamp blackberry
(Rubus hispidus), underneath abundantly infected hemlock trees,
was found infested with Kuehneola albida. Examples were seen
here where the two hosts almost touched each other, each
infected with its fungus, and in general the swamp blackberry
had its rust only when situated beneath infected hemlock trees.
A few days later, at Stafford Springs, another case was found
where infected leaves of the hemlock were close to rusted leaves
of the swamp blackberry, while other specimens of the blackberry
further away were free. As no other rust was at any time found
so situated as to suggest a probable relationship, the writer
became convinced of the connection of these two.
Infection experiments in the greenhouse, using spores from
this Peridermium on leaves of Ruhus hispidus, were tried on
three different occasions, but no infection resulted, except pos-
sibly in one case when one sorus of the II stage of this Kuehneola
appeared about sixteen days afterward. As the plants used were
recently transplanted, most of the leaves finally dropping off,
this might explain the failure to infect the host; but on the other
hand, as the plants came from an infected region, though from
a spot apparently free from the rust, the single sorus that finally
developed may not have come from the spores used, but from
a previous outdoor infection.
The most unfavorable point against the relationship of Peri-
dermium Peckii and Kuehneola albida, however, is that with this
Peridermium on the hemlock leaves there occurs a pycnial stage,
while with the Kuehneola on the Rubus host there is sometimes
found a uredinial stage known as Uredo Muelleri also having
pycnia. This Uredo is believed by some, though its exact rela-
tionship apparently has never been proved by cultures, to be
merely the primary uredinium (IP) of the Kuehneola. If it
really is, then the Peridermium probably has no relationship to
the Kuehneola, since no rust is known that has pycnia connected
with more than one of its stasres. From these considerations it
HETEROECIOUS RUSTS. 305
readily appears that further infection experiments are necessary
to determine the relationship, if any, of Peridermium Peckii,
Uredo Muelleri, and Kuehneola albida. Farlow (lo, p. y2) has
also suggested a possible relationship of P. Peckii to Calyptospora
Goeppertiana; and it is barely possible, though not likely, that it
is connected with the Necium discussed later.
ir. Plate XXIX, b. Uredo Muelleri Schroet. differs from
the II stage of Kuehneola albida in having its sori in groups
usually on the upper side of the leaves, a few large uredinia and
pycnia occurring together there, while the smaller uredinia of
Kuehneola occur scattered on the under side of the leaves and
without pycnia. Mueller, who first described the species as
Uredo aecidioides, according to Schroeter (Krypt. Fl. Schl. IIP:
375) thought that it might possibly be the aecial stage of
Chrysoniyxa albida, since both were found together. That they
have some relationship is further indicated by the fact that not
only have they been found together in Europe and also in
America, but on several different species of Rubus. In the speci-
mens collected in Connecticut on Rubus hispidus, both at Storrs
and Stafford Springs, this Uredo occurred on the same plants
with the II and III stages of Kuehneola albida. The two have
also been found elsewhere in New England associated on this
same host. Dietel (Hedw. 44: 122. 1905) has recently sug-
gested that Uredo Muelleri, instead of being the aecial stage of
Kuehneola albida, is a primary uredinial stage of it that merely
functions as the aecial stage.
II, III. Plate XXIX, c. The II or uredinial stage of
Kuehneola albida is the more common and injurious of these
two stages. It has been reported on several species of Rubus
from the United States, and extends over a wide district. While
not a very common fungus, when it does occur it is often abun-
dant. The sori are very small, and show as yellowish circular
outbreaks scattered over the under side of the leaves. The telial
sori often occur on the same leaves with these, but are easily
distinguished by their white color. The telial spores found here
last summer had all germinated before the middle of July. In
the specimens first found on the swamp blackberry both of these
stages occurred on the old leaves (the III being limited to these)
that had lived over the winter, and as we have also found the
II stage as late as November 30th, we have no doubt but that on
28
386 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
this host the fungus carries over the winter through the uredinial
stage, and so the I stage is not essential for its appearence the
next year. The collections so far made in this state are as fol-
lows : Ruhus hispidus, Storrs, II and III, July 22, II, Oct.
18, 1907; Stafford Springs, II and III, July 31, 1907; West-
ville, II, Nov. 30, 1907; Ruhus villosus, Storrs, II, July 23,
II, Sept. 30, 1907.
6. Melampsoridium Betulae (Sclium.) Arth.
Plate XXXI, b. (From a specimen in Seym. Econ. Fungi
2^ij b). This is a fungus that is not very often collected in the
United States, but apparently occurs as frequently in New Eng-
land as anywhere. Though careful search was made for it in
Connecticut the past season, it was not found. The writer, how-
ever, is indebted to Professor Farlow for specimens collected
on September 20, 1890, by Setchell at Norwich, on Betula populi-
folia. Only the II stage occurs on these. While both the II and
III stages have been found in the United States, the I stage has
never been seen here. According to Klebahn (Zeitschr. Pflan-
zenkr. g: 18. 1899) this stage occurs on the leaves of Larix, and
has been found in several places in Europe. A careful search for
this [Peridermium Laricis (Kleb.) Arth. and Kern] on wild and
cultivated larches in this state last year gave no evidence of its
presence. Just how the fungus passes the winter in this country
and reappears on the Betulae is unknown. As the leaves of the
Betulae do not survive the winter, reinfection from the II stage
on them is not probable. Though not known, possibly the
uredinia sometimes occur on the young twigs, and by this means
carry over the fimgus.
7. Melampsoropsis Cassandrae (Pk. & Clint.) Arth.
(I. Peridermium consimile Arth. & Kern.)
I. Plate XXX, a. The writer (7) has recently shown the
relationship of Peridermium consimile on Picea nigra to
Melampsoropsis Cassandrae on Cassandra calyculata. Both of
these fungi were found in Connecticut for the first time last year.
The only locality in which the Periderm.ium was found was in
a spruce swamp along the railroad just beyond West Willing-
ton toward Stafford Springs. When first seen there on July 31st,
HETEROECIOUS RUSTS. 387
the aecia were just beginning to shed their spores, and when
seen again on September 28th, they were far beyond their prime.
The aecia occur irregularly in one or two rows on the leaves,
usually four to eight on each leaf. The infected leaves are dis-
colored yellowish, and look as if they would be shed prematurely,
but there is no indication of a witches' broom formation. The
peridia, as shown in the illustration, are somewhat flattened, and
about as long as high. They break open irregularly at the top
to shed the orange-colored spores, and then gradually wear away.
A striking feature of this species is the very conspicuous reddish-
brown pycnia, which show plainly in the illustration as the small
black specks.
The only rust suitable for the alternate stages found in the
vicinity of this Peridermium during the season was the II stage
of Melampsoropsis Cassandrae on the leather leaf under the
infected spruce trees. Specimens of the leather leaf from the
edge of the swamp, away from the infected spruces, were col-
lected and transplanted in crocks in the greenhouse. These
were watched carefully, and two or three plants, upon which a
sorus or two of the Melampsoropsis appeared, were discarded.
Other specimens apparently entirely free from the rust were
inoculated with the spores of the Peridermium, and about six-
teen days later the uredinial sori appeared on a number of the
plants. This experiment was repeated a short time later, using
spores from leaves for a short time in a damp chamber, and the
infection took place in this case in about eight days. Infection
experiments with the spores on Rubus hispidus and Pyrola
elliptica failed to produce anything. While necessity compelled
the use of Cassandra calyculata from the infected locality, the
results indicated that the sori obtained came from the Perider-
mium spores used in the experiments. It is hoped, however, to
repeat the inoculations again the coming year with plants
entirely above suspicion.
II. Plate XXX, b. The uredinia occur as minute orange-
yellow dusty outbreaks on the under side of the leaves. So far
we have been unable to find any suggestion of the telial stage on
this host, though a careful search was made for it during July,
September, October, January and February.* Arthur describes
this stage, but apparently from other hosts. Last October the
II stage was found on the leather leaf in Beaver Swamp, at
*See addenda, p. 396.
388 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
Westville, and as no spruce trees are anywhere near, there is no
doubt that the fungus can survive without the aid of the aecial
stage. In January a careful examination of the plants in this
locality was made, and a few old uredinia were found on the
living leaves, which largely remain on the plants over the winter.
Some of the branches, after the infected leaves were removed,
were placed under a bell jar indoors, and a few new uredinia
soon appeared, no doubt from nearly matured sori. No others
showing during the next week, the branches were left undis-
turbed for about a month, when an examination revealed several
hundred uredinia present. These observations show that the
fungus can pass the winter, on the old but living leaves that
adhere to the plants, through the more or less matured uredinia,
or no doubt in some cases, when infection takes place late in the
season, through localized mycelia which gives rise to the uredinia
in the spring.
8. Melampsoropsis Pyrolae (DC.) Arth.
Plate XXXI, a. This is commonly known as Chrysomyxa
Pyrolae, and occurs in the United States chiefly in the North-
eastern States and the Rocky Mountains on various species of
Pyrola. So far in this state only the II stage has been found,
and this is striking when once detected, since the under surface
of the infected leaves is thickly covered with brightly colored
uredinia. The collections for this state are as follows : Pyrola
elliptica, Storrs, May, 1904 (Graff) ; Pyrola rotundifolia, Pine
Rock in Westville, May, 1894 (Sturgis, Fungi, Col. 18 14) ; West
Rock, 1902 (Clinton); Vernon, May 25, 1907 (Weatherby).
No aecial stage has yet been discovered for this species.
According to Arthur and Kern (5, p. 432), Rostrup has sug-
gested that P eridermium conorum-Piceae (Reess) Arthur and
Kern may have this connection, since both are found in some-
what the same localities in Europe and America. A search for
this Peridermium failed to reveal its presence in Connecticut,
though possibly it occurs in the northwestern part of the state
since it has been found in New York and Northern New Eng-
land. Apparently the aecial stage is not necessary for the
appearance of the rust, as the leaves of the Pyrolae frequently
live over the winter and could easily carry over the uredinial
stage.
HETEROECIOUS RUSTS. 389
9. Necium Farlowii Arth.
This species, found on hemlock, Tsuga canadensis, has recently
been made the type of a new genus by Arthur (2, p. 114), who
bases his description on material furnished by Farlow, and col-
lected by Seymour at Chebacco Lake, Mass., and by Farlow at
Lake Sunapee, N. H. Arthur describes only the telial stage, and
characterizes the genus as having only telia and possibly pycnia.
He neglects to state, however, that Seymour collected at the
same time, and possibly on the same trees, a species of Caeomia
which might very well be the aecium of this fungus. Farlow
(9) was the first to call attention to these fungi. He says : —
"Besides our common Chrysomyxa on Pyrola, a species was
found on Abies Canadensis at Chebacco Lake, Essex Co., Mass.,
by Mr. A. B. Seymour, in June, 1883. This is probably the same
as Chrysomyxa Abietis of Europe, although, as the spores were
not quite ripe, one cannot be certain. If there is a difference,
it is to be found in the fact that the teleutospores are arranged
in threads, which branch less than the European forms. But at
a later stage of development, this supposed difference might
disappear. At the same time and place Mr. Seymour found
another interesting species of Urediniae, also on Abies Canaden-
sis, not on the same branches as the species last mentioned, nor on
the same trees, as far as can now be ascertained. Sper-
magonia were abundant on both sides of the leaves, on whose
under surface were elliptical or elongated sori of a pale yellow
color, arranged in two rows parallel to the midrib. The spores
were globose, or somewhat elliptical, about 13-17 /a in length,
and appeared to be borne in chains, composed of a small number
of spores. It is possible that this form is Caeoma Abietis-pec-
tinatae Reess, of which I have seen no specimens. From the
description of Reess, however, this species has larger spores than
ours, and no mention is made of spermagonia. It may be well
to designate our form under the name Caeoma Abietis-Cana-
densis until more exact information can be obtained."
The writer is indebted to Professor Thaxter for a specimen
of this Necium collected by him on the cones of hemlock at
Hamden, Conn., July 18, 1889, and for another on the branches
and leaves from North Carolina. While these specimens show
only the telium, Thaxter wrote on the label of the Hamden
specimen, "teleutospores of Caeoma on hemlock cones," and in
39° CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
a letter written to Professor Farlow, July 12, 1890, said: "I
sent you yesterday fresh cones with mature teleutospores, one
having both Caeoma and teleuto forms side by side. I found a
quantity of material at New Hartford, Conn., but a careful
examination of the leaves on branches where the infected cones
were hanging by dozens revealed nothing. The 'Chrysomyxa'
which I formerly sent you from North Carolina on the same host
occurred only on young shoots, running from them into the
leaves. Though very common in North Carolina, I did not find
it on the leaves of any but affected shoots. I find nothing of
the sort here, though I have looked for these affected shoots,
which are conspicuous. I have found the Caeoma on shoots, of
which I sent you a specimen, twice only." The writer has never
collected this Necium in Connecticut, though Thaxter found it
not uncommon at the time of his collections, but has seen a
specimen of Caeoma Abietis-canadensis found by Dr. Britton
very sparingly in June, 1906, on hemlock leaves in Westville.
Arthur describes the Necium as occurring on the leaves, while
Thaxter's specimens show the telia on the cones and young stems
as well, thus indicating that it is sometimes perennial. On the
cones and twigs, at least, the spores seem to originate beneath
the epidermal cells instead of in them, as stated by Arthur. The
sori on these parts are also often crowded together so that the
spores from a continuous layer (especially on the cone scales),
across the entire microscopic section. (Plate XXXII, 5.) This
gives them the general appearance ®f being an epidermal layer
of the plant tissues, though they are quite unlike the true epi-
dermal cells. The sori, where distinct, range from 60 — 120 /u.
in depth by 70 — 300 in length. The simple, slightly tinted
oblong spores are very closely compacted together, so that in
mature sori they are narrower and more elongated than in the
immature. Frequently they are slightly broader and more deeply
tinted at the apical end, and very rarely have a septum above
their base. They seem to be somewhat larger than those on the
leaves, as given by Arthur, since they vary from 40 — 85 /j. in
length by 6 — 14 /j- in width, the shorter and broader often being
immature. They arise from septate basal cells of about equal
diameter, which in turn develop from the mycelial threads that
ramify through the plant tissues beneath. In sections of the stem
the mycelium shows ver}^ abundantly and no doubt is responsible
HETEROECIOUS RUSTS. 391
for the. distortion of the young stems, which are slightly swollen
and sometimes more or less curved. The fungus gives a reddish
tinge to both the infected stems and cones, due to the superficial
colored sori.
While not exactly like Chrysomyxa Ahietis, which has septate
spores, and even less like Calyptospora Goeppertiana, this species
has perhaps more the characters of the Melampsora-like genera,
so everything considered, it will perhaps rest easiest for the time
being in the new genus created for it by Arthur. While there is
no positive proof that Caeoma Abietis-canadensis has any con-
nection with the Necium, the fact that a Caeoma has been found
on the leaves, cones and stems, and in some cases associated
with the Necium, very strongly indicates a relationship. If this
is so, or if Arthur is correct in believing that the Necium has no
other stage, of course the fungus does not really come within
the limits of this article. It is included here because of the
possibility that it may have for its aecial stage some species of
Peridermium. For example, Peridermium Peckii occurs on the
same host, and there is a bare possibility that the two are con-
nected, since Professor Farlow writes that he found them near
together at Lake Sunapee.
ID. Pucciniastruni Agrimoniae (Schw.) Tranz.
Plate XXXI, c. So far no aecial stage has been found for
this fungus, which in its uredinial stage is rather common in
Europe and America. Presumably if it possesses an aecial stage,
this is one of the Peridermia since, where known, species of
this genus have such connection. The uredinia occur on the
under side of the leaves of various species of Agrimonia, forming
numerous, scattered, pale-orange or yellow, minute outbreaks,
as shown in the illustration. The uredinia of this genus have a
rather definite peridium, which opens by a pore, guarded by
more or less differentiated neck cells. In this species the peridia
are not sunken very deeply in the tissues, and are held in place by
the overlapping epidermis. In general they are lenticular to sub-
circular in cross section, and vary from 90 — iSoju. in height by
160 — 360 fx in width. The neck cells are somewhat differentiated,
but are not nearly so characteristic as in some of the other species
(P. arcticiim americanum, see Plate XXXII, 3), being somewhat
larger, thicker walled, and more spore-like in appearance than the
392 CONNECTICUT EXPERIMENT STATION REPORT^ I907-I908.
Other peridial cells, which are frequently rather indistinct and
semi-gelatinized. The spores are rather sparsely covered with
inconspicuous echinulations, vary from ovoid to subspherical,
occasionally flattened or more irregular, and are 15 — 20 /x, rarely
24 /A, in length.
The telia of this fungus were first described by Dietel (Hedw.
29: 152) in 1890, but are not commonly recognized, probably
because they develop late in the season, and in the specimens we
have collected do not show to the naked eye. In cross sections
of the leaf of one of the collections made on October 17, this
stage was shown to be present. The sori occurred beneath the
epidermal cells, and were characteristic of true Pucciniastrum
telia; that is, in cross section the spores showed as twin cells,
but when viewed from above, as four cells firmly bound together
(see illustration, Plate XXXII, 4). Where the sori are abundant,
the individuality of the cells is almost entirely lost by being
crowded together. The compound spores vary from oval to sub-
spherical, and are about 19 — 28 ju. in length.
11. Pucciniastrum minimum (Schw.) Arth.
Neither the aecial or telial stage is known for this fungus
according to Arthur. We found its uredinal stage on cultivated
Azalea sp., August 14th, 1902, in a Westville nursery, where
it was very abundant. No clue was obtained to its other stages,
and as these plants were soon disposed of, it has not been seen
since. The aecia show as very minute orange-yellow out-
breaks on the under side of the leaves. The peridia are slightly
imbedded in the tissues, are hemispherical to conical flattened,
and about 70 — 85 ju, high by 140 — 180 /a wide. The neck cells
are thick-walled, and not especially marked or prominent. The
spores are ellipsoidal or occasionally more elongate, minutely
echinulate, and 16 — 25/1* in length.
12. Pucciniastrum pustulatum (Pers.) Diet.
In Europe the above species has been connected by Klebahn
(Zeitschr. Pflanzenkr. 9: 22-6. 1899) with a Peridermium on
Abies pectinata, but so far the aecial stage has not been found
in this country. Possibly Peridermium balsameum Pk., a related
species on Abies balsamea, is this stage, though according to
Farlow (10, p. 20) it has been conjectured that this Perider-
HETEROECIOUS RUSTS. 393
mium belongs to the American species of the Calyptospora on
Vaccinia. Blakeslee sent the writer, in August, 1907, Perider-
mmm balsameum from the Adirondacks, where the only suspi-
cious alternate forms found were the II and III stages of Puc-
ciniastrum arcticum var. americanum Farl. on Rubus strigosus.
(Described in Rhodora 10:13. Ja. 1908.) Thus, while the
specific ties of this Peridermium are doubtful, it seems certain
that it is connected with some Pucciniastrum (in the wide sense,
including Calyptospora).
The II and III stages of Pucciniastrum pustulatum occur on
various species of Epilobium scattered over the United States.
Only one collection, and then only of the II stage, has been made _
in this state, on Epilobium sp., at Hartford, Oct. 20th, 1902.
The peridia seem to be composed of plant and fungous cells, and
are hemispherical or decidedly flattened, slightly immersed in
the tissues, and about 45 — 115 /j. high by 165 — 300 /a wide. The
neck cells, while somewhat more prominent than the other peri-
dial cells, have no especial markings, and seem to be rather
fugacious.
13. Pucciniastrum Pyrolae (Pers.) Diet.
This is another species of Pucciniastrum widely distributed
over the United States, whose aecial stage is unknown, but
which, like the others, is supposed to be a Peridermium. The
only specimens collected in this state were of the II stage, found
at Storrs, July 24, 1907, on Pyrola elliptica. This is a much less
conspicuous fungus than the Melampsoropsis Pyrolae which
occurs here on the same host. Apparently the fungus carries
over the winter through the uredinia on infected leaves. While
no clue to its aecial stage was obtained, it is not likely to be either
Peridermium Peckii or P. balsameum, since infection experi-
ments with these species on this host failed to give results.
SPECIES NOT YET REPORTED BUT PROBABLY OCCURRING IN CONN.
The following species have not yet been found in this state,
but very probably will be collected here sometime as they have
been Hsted from adjacent states.
I. Calyptospora columnaris (Alb. & Schw.) Kuehn (C. Goep-
pertiana) on Vaccinium sps. (I. Peridermium columnar e
(Alb. & Schw.) Schm. & Kze. on Abies sps. Not yet
394 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
reported in America. Peridermium Peckii and P. balsameum
have been suggested as possibly belonging to this Calyptos-
pora.)
2. Coleosporium Helianthi (Schw.) Arth. on Helianthus sps.
(Peridermium unknown.)
3. Coleosporium Senecionis (Schum.) Fr. on Senecio sps. (I.
Peridermium oblongisporium Fckl. on leaves of Pinus
sylvestris. Not yet found in America.)
4. Cronartium Comandrae Pk. on Comandra umhellata. (Peri-
dermium unknown.)
5. Cronartium rihicola Waldh. on Ribes sps. cult. (I. Perider-
mium Strohi Kleb. on branches of Pinus Strobus. Liable
to be introduced on white pine imported from Europe.)
6. Melampsorella elatina (Alb. & Schw.) Arth. {M. Caryo-
phyllacearum) on Caryophyllaceae. (I. Peridermium elati-
num Alb. & Schw., Schm. & Kze. on A^ies balsamea.)
7. Pucciniastrum arcticum americanum. Farl. on Rubus strigo-
sus. See PI. XXXII, 3. (Peridermium unknown but pos-
sibly P. balsameum; see page 393.)
8. Pucciniastrum Myrtilli (Schum.) Arth. (P. Vacciniorum)
on Gaylussacia sps. and Vaccinium sps. (Peridermium
unknown.)
LITERATURE.
The following are a few of the American references relating
to our Peridermia and their probable alternate stages :
1. Arthur, J. C. Peridermium on Pinus rigida. Joum. Myc. 11: 52.
Mr. 1905.
Failed to infect leaves of Lobelia syphilitica with spores of above
fungus.
2. Arthur, J. C. Uredinales. North Amer. Flora. 7: 85-123. Mr.
1907.
Gives within these pages the heteroecious rusts of N. A. having
Peridermia for their aecial stage, describing all the stages so far
as known.
3. Arthur, J. C. Cronartium Quercus (Brond.) Schroet. Journ. Myc.
13: 194. S. 1907.
Produced above fungus on Quercus velutina, but not on Q. alba,
by using spores of Peridermium cerebrum from Pinus virginiana.
4. Arthur, J. C. Peridermium pyriforme and its probable alternate
host. Rhodora 9: 194-5. S. 1907.
Suggests from observations made by Dr. Thorn of Conn., that
the above is the aecial stage of Cronartium Comptoniae.
HETEROECIOUS RUSTS. 395
5. Arthur, J, C. and Kern, F. D, North American species of Peri-
dermium. Bull. Torr. Bot. Club 33: 403-38. Au. 1906.
Give general discussion, keys, descriptions, synonyms, hosts, and
distribution of thirty species.
6. Clinton, G. P. Peridermiwn acicolum, the aecial stage of Coleo-
sporium Solidaginis. Science 25: 289-90. F. 1907. (Also note in
Ann. Rep. Conn. Agr. Exp. Stat. 1906: 320. My. 1907.)
Proves by observations and inoculation experiments the rela-
tionship of the above rusts.
7. Clinton, G. P. Notes on certain rusts with special reference to their
Peridermial stages. Science 27: 340. F. 1908.
Proves by infection experiments the relationships of Peridermium
pyriforme to Cronartium Comptoniae and P. consimile to Melamp-
soropsis Cassandrae, and suggests possible relationship of P. Peckii
to Chrysomyxa albida.
8. Farlow, W. G. Appalachia 3: 239-43. Ja. 1884.
Gives notes on Peridermia of the White Mountains.
9. Farlow, W. G. Notes on some, species of Gymnosporangium and
Chrysomyxa of the United States. Proc. Amer. Acad. Arts Sci.
20: 322-3. 1885.
Gives notes on Chrysomyxa Ledi, II, III, and Uredo Ledicola, on
Ledum, and suggests Peridermium (probably P. Abietinum) on
Abies nigra may* be associated with former; thinks Aecidium
pseudo-columnare of Kuehn may be the same as P. balsameum of
Peck; also gives notes on Chrysomyxa Abietis (?) and Caeoina
A bietis-Canadensis.
10. Farlow, W. G. Aecidium sps. Bibl. Ind. N. A. F. S. 1905.
Gives bibliography of the species of Peridermium (under the form
genus Aecidium) with notes upon the following: Aecidium Abie-
tinum (p. 13), A. balsameum (p. 20), A. carneum (p. 25), A. cere-
brum (p. 2y), A. conorum-Piceae (p. 35), A. decolorans (p. 38),
A. deformans (p. 39), A. elatinum (p. 40), A. ornamentale (p. 71),
A. Peckii (p. 72), A. Pini (p. 75).
11. Farlow, W. G. and Seymour, A. B. Prov. Host Index Fungi U. S. :
158-170. 1891.
List, under the various hosts, species of Peridermia that have
been reported for the U. S.
12. Freeman, E. M. Minnesota Plant Diseases: 275-7. Jl- 1905.
Gives notes on pine stem rust, leaf rust of pines (suggests rela-
tionship to rusts on asters and goldenrod), and witches' broom of
balsam fir.
13. Kellerman, W. A. Pine rust, Peridermium Pini. Journ. Myc. 11: 32.
Ja. 1905.
Sowed spores of "Peridermium Pini" obtained from Ohio on
Campanula Americana outdoors and produced urediniospores, thus
proving the fungus on the pine to be the aecial stage of Cole-
osporium Campanulae.
396 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
14. Peck, C. H. Perideriniuvi pyrifonne Pk. Bull. Torr. Bot. Club
6: 13. F. 1875.
Describes this as a new species on pine branches, probably from
Newfield, N. J.
15. Seymour, A. B. Peridermium Pini Lev. var. acicolum Wallr. Eco.
Fungi 223. 1893.
States that this species on Pinus rigida is commonly associated
with Cronartium on Myrica asplenifolia.
16. -Shear, C. L. Periderviiuni cerebrum Pk. and Cronartium Quer-
cuum (Berk). Journ. Myc. 12: 89-92. My. 1906.
Gives results of outdoor inoculation experiments by which the
Peridermium is shown to be the aecial stage of the Cronartium;
gives hosts and distribution of each.
17. Underwood, L. M. and Earle, F. S. Notes on pine-inhabiting
species of Peridermium. Bull. Torr. Bot. Club 23: 400-5. O. 1896.
Give notes on three species from Eastern U. S., and mention
three others from the western part which they have not examined.
ADDENDA.
(i) See Kuehneola albida, p. 383. The writer is indebted to Professor
Farlow for calling his attention to an infection experiment with this
rust by Ernest Jacky, published in the Cent. Bak. Par. Infek. 18: 91-3.
February, 1907. This writer claims to have produced Uredo Muelleri on
Rubus fruticosus from Phagmidium [Kuehneola] albidum on the same
host. As this experiment was conducted in the woods merely by laying
infected leaves on the plants, and as these leaves came from plants which
also contained Uredo Muelleri at that time, there may be some question
about his conclusion. In a late more careful experiment, using Uredo
Muelleri he produced Uredo Muelleri, apparently as he claims.
(2) See Melampsoropsis Cassandrae, p. 386. On May 4, 1908, just as this
paper was going to press, the writer succeeded in finding the III stage of
the above fungus on Cassandra calyculata, at Beaver Swamp, Westville,
on the same plants that the II stage was found on during the previous
fall and winter. The sori are small, about one-eighth of an inch or less
in diameter, are situated on the under surface of the leaves (though
also discoloring the upper surface) and show to the naked eye as slightly
elevated, waxy, chestnut-red areas. These may be distinct or somewhat
run together, and under a hand lens seem to consist of more minute
divisions really caused by the leaf venations. The sori at this time were
scarcely mature, but undoubtedly some of them would mature very
shortly. Their season, apparently, is from May to June, which is
the only time of the year I had not before looked for this fungus.
PLATE XVII.
a. Baldwin Spot, p. 340.
b. Spray Injury, p. 342.
TROUBLES OF THE APPLE.
PLATE XVIII.
a. Chestnut Bark
Disease, p. 345.
b. Anthracnose of Currant, p. 347.
c. Bitter Rot of VViiite Currants, p. 347.
FUNGI OF CHESTNUT AND CURRANT.
PLATE XIX.
a. On young Currant shoot.
b. On fruit of Gooseberry.
POWDERY MILDEW, Spimcroihcca iiiors-itvar, p. 348.
PLATE XX.
a. Leaf Scorch of Farleyense Fern, p. 349.
b. Rust of Juneberry, p. 351.
DISEASES OF FERN AND JUNEBERRY.
PLATE XXI.
HERBARIUM
CONN. AGR.
e:x
.p. STA
• l^
w
^p ^^^
•
% <
^
9
^3
«
9 #
%.
Q
•
#
1 %
#
%
*l
a. Sclerotia from the soil. X 2.
b. Artificial cultures on corn meal and agar.
STEM ROT FUNGUS OF HERBACEOUS PLANTS, p. 351,
PLATE XXII.
Healthy.
Diseased.
a. Showing effect on size of leaves.
b. Showing injury to leaves. X 2.
BLIGHT OF WHITE PINE, p. 353.
PLATE XXIII.
a. Internal Brown Spot, a
physiological trouble,
p. 355.
b-d. Scurf, caused by Spondylocladiinii fungus, p. 357.
b.
Surface of tubers greatly X .
■•',>jjj?f -■-
c. Spore stage. d. Sclerotia.
DISEASES OF POTATO TUBERS.
PLATE XXIV.
a. Formalin. (Plot i]
b. *Steam. (Plot 2)
c. Weak formalin sprinkled.
(Plot 5)
d. Check, no treatment.
(Plot 6)
(♦Shortly before photographing, the best plants were pulled, so this should really show-
somewhat better than a.)
TREATMENT OF TOBACCO SEED BEDS FOR ROOT ROT, p. 365.
PLATE XXV.
a. I on Pinus rigida. X 4.
b. II on Campanula rapiinculoides. X 2.
4>-^<(^SC''^4>*4»
c. Ill on Cainpanula rapiinculoides. X 4.
{Peridermiuni Rosliiipi), II, III STAGES OF Colfosporim/i Caiiipa/iiilat', p. ^,74.
PLATE XXVI.
a. Showing a bunch of infected leaves natural size. I.
O. I.
b. O, I on Finns rigida. X 8.
0, I {Pei-ideruiiimt acicoluin) , STAGES OF Coli-ospoiiinii So/idai;iiiis, p. 375.
PLATE XXVII.
a. II on Solidago rugosa. Natural size and X 8.
b. Ill on Solidago ntgosa. X6.
II, III STAGES OF Coleosporiioii Solidaginis, p. 377.
PLATE XXVIII.
On Pimis sylvestris.
"i^^B^H^r^^^ ^S^y^*^^
w^
Lj^S^„„- i^^'^alF^^:::,^ '-^
\. wK^^^m^^'' 1
^
^^^prlj^JNi^^^
p-^
*^hIO^^ ifflK*". ^''^^"^
^^HbbBBhII^IIKi "^^P* ^^ --Jk
a. I natural size. b. 1X2.
On Comptonia asplenifolia .
c. II X 4. d. Ill X 4-
{Peridermiujii pyrifonne), M, III STAGES OF Croiiar/ium Ccnnp/oniae, p. 3S0.
PLATE XXIX.
a. I Peridennium Peckii on Tsiiga canadensis.
b. ir Uredo JMiielleri on Rubus hispidus.
c. Ill Kiteluieola albida on Rubus Iiispidus.
ir, 111 STAGES (X 4) POSSIBLY OF THE SAME RUST, p. 383.
PLATE XXX.
a. O, I on Pice a nigra.
b. II on Cassandra calyciilata.
0, I {Peridcrmiuvi consimile), II STAGES (X 4) OV Mclauipsoropsis Cassa)idrac, p. 386.
Melampsoropsis Pyrolae, p.
PLATE XXXI.
3felainpsoridiuiJi Betulae, p. 386.
a. On Pyrola rotundifolia. X 4.
b. On Betula puiiiila. X 2.
c. Piicciniasfruui Agrimouiae on Affriuioiiia sp., p. 391. X 2.
II STAGE OF THREE HETEROECIOUS RUSTS.
PLATE XXXII.
a. spores; b. germ tubes; c. peridial cells; d. peridium; e. neck cells
of peridium; f. epidermal cells of host; g. parenchymatous cells of host;
h. mycelium; i. fertile cells of mycelium, i'""* (i) Peridet'iniiini acicoluui;
(2) P. pyriforme ; (3) P. Peckii; (4) P. consii)iile. 2'"'^ Germination of II
spores of (i) Coleosporiiim Solidaginis and (2) C. Campanulae . 3. Partial
section through peridium of Pncciniastruni arcticuui var. a)iiericanii}>i.
4'^'^ Compound spores, III, of Piicciniastriim Agrhnouiae, shown in longi-
tudinal (i) and cross (2) section. 5' - Cross section through telia of
Neciuin Farlowii on stem (i) and on cone (2).
I, II, III SPORE STAGES OF CERTAIN RUSTS.
,U to
>- _?:> X i_%i t,.t 'i.e**
i\
i f '--
^ cl-in^etts
A:
ultural
State of Connecticut
REPORT
OF
The Connecticut Agricultural
Experiment Station
REPORT OF THE STATION BOTANIST, 1908
G. P. CLINTON, SC.D.
BEING PART XII OF THE BIENNIAL REPORT OF I907-I908
CONNECTICUT
AGRICULTURAL EXPERIMENT
STATION
REPORT OF THE BOTANIST
G. P, CLINTON, ScD,
PAGE
I. Notes on Fungous Diseases, etc., for 1908, 849
A. General Notes on Diseases previously reported, . . . 849
B. New Observations on Diseases previously reported, . . 853
C. Diseases not previously reported, S58
II. Peach Yellows and so-called Yellows, 872
III. Chestnut Bark Disease, Diaporthe parasitica Murr., .... 879
IV. Artificial Cultures of Phytophthora, with special reference
to oospores, 891
ISSUED JULY, 1909
PART XII.
REPORT OF THE BOTANIST FOR 1908.
G. P. Clinton, Sc.D.
I. NOTES ON FUNGOUS DISEASES, ETC., FOR 1908.
A. GENERAL NOTES ON DISEASES PREVIOUSLY REPORTED.
Weather conditions. The winter of 1907-08 was on the whole
rather mild, so that no very general winter injury resulted to the
shrijbs and trees. During the latter part of January and in
February, however, the cold was sufficient to kill a good many
of the peach buds. Likewise, certain peach trees suffered some-
what from the collar girdle injury, which is described elsewhere.
The spring of 1908 was one of the earliest and driest that we
have had in some years, the early vegetables being a week or two
in advance of the average year, and considerably more than that
as compared with the year of 1907, which was tmusually late.
The summer, like that of 1907, was unusually dry, but differed
in that the drought came in two periods. The first drought
extended into the middle of July. The latter part of that month
and most of August were sufficiently moist for the needs of.
vegetation in general ; but the last of August and practically all
of September were again free from rains. The splitting of the
drought by the scattered rains during midsummer had the effect
of keeping down drought injury much below that of 1907, when
the dry weather lasted from June until August.
While the drought did harm to certain of our crops, such as
alfalfa, asparagus, potatoes and celery, on the other hand, some,
like the peach, muskmelon and tobacco, were in the end benefited
by the dry weather, especially by that of the late summer and
fall. The comparatively dry weather of the growing season as
a whole was sufficient to keep down most parasitic fungi, so that
1908, like the past few years, was not one in which these pests
(with a few exceptions) did any great injury to our cultivated
plants.
60
850 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
The fall frosts held off somewhat later than usual, the first
one of consequence coming on October 12th, the slight frost of
October 5th merely injuring the cucurbits.
Market garden and other plants. There were a number of
complaints of the premature yellowing and dying of alfalfa
plants, these being affected sometimes in spots. While we did
not have the opportunity of examining the plants in the fields,
from the absence of any sure signs of fungous or insect attack
on the specimens sent to the station, we were inclined to believe
that the trouble was due to the dry weather. Certain weeds,
such as the pigweed, often showed similar injury, due to the
drought.
While the rust of asparagus was more common than usual, it
did not do as much harm as the drought. Nearly all asparagus
beds suffered from the dry weather, so that the tops were fre-
quently dead early in September. Such injury from drought is
likely to show itself the following spring in a lower yield of tips.
The anthracnose of string beans was conspicuous by its absence
this year, and the downy mildew of the Lima beans only appeared
at the very end of the season, when it was too late to do any
harm.
The muskmelons were better this year than for some years
past, in yield and especially in quality. Connecticut melons on
the Boston market were unusually fine. This was due to the
warm, dry weather which is so essential to this crop, and which
also helped to keep down its fungous enemies. However, during
the latter part of the season many of the vines were injured or
prematurely killed by the attacks of the downy mildew and the
leaf spot blights.
The blight, or downy mildew, of the potato, so far as the writer
could discover from a careful search during the season, did not
occur at all, it being the first time in seven years, at least, that it
was not found. This meant that there was no injury by rot to
the tubers. But while the potatoes escaped the blight, due to the
dry season, from the same cause they suffered unusually from
tip burn, so that practically all the vines, especially of the late
varieties, were prematurely killed, and the yield very greatly
reduced. In some fields the tubers were scarcely marketable.
There was some scab, it being reported as quite bad in certain
fields.
NOTES ON FUNGOUS DISEASES FOR I908. 85 1
The midsummer rains prevented much injury resulting from
the drought to the tobacco fields, while the dry spell of the fall
favored its harvest and curing in the barns. As a result the
tobacco crop was unusually good. No complaint was made of
serious root rot in the seed beds, and, so far as we have heard,
the trouble in the fields, due to the Thielavia fungus and other
causes, was not especially conspicuous in the Suffield region. In
some fields there was more or less calico. (Plate LXVIb.)
This is a trouble to which we have paid especial attention during
the past two years, and we expect next year to give an account
of these investigations.
Fruits and berries. While the apple crop was comparatively
small and of rather poor quality, this was not due to any especial
attacks from fungi. By far the most conspicuous apple fungus
of the year was the leaf rust (Roestelia pirata). Conditions
must have been unusually favorable in the spring for its spread
from the "cedar apples," its winter stage on the red cedars, for
it occurred on apple trees in some cases quite distant from any
cedars. It was one of the fungi most frequently sent in for
identification.
The peach apparently suffered more than any other fruit tree
from fungous and physiological diseases the past year. While
the scab and brown rot were less noticeable than usual, the latter
largely because of the favorable dry weather at harvest time, the
bacterial spot was more common than at any time since we first
called attention to it in 1903. There was also considerable injury
from collar girdle in some orchards. Yellows and so-called
yellows were very prominent, especially in certain orchards.
While the peach crop was not as large as some years, the quality
was above the average.
With the quince, as with the apple, rust (Plate LX c) was
unusually prevalent, especially in the vicinity of New Britain.
The quince rust (Roestelia aurantiaca), however, generally
attacks the fruit and the young stems, especially the fruit-spurs.
Its mycelium in the stem, so far as we have been able to learn,
is not perennial, so that infection each year depends upon the
"cedar apple" stage. It forms elongated but quite fragile white
peridia that rise above the infected parts and are filled with
bright orange-colored spores. The half-tone shows a quince in
which these peridia have worn off.
852 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
Among the diseases of the small fruits, the downy mildew of
the grape and the yellows of raspberries were the only ones to
which our attention was called as being unusually common. We
also noticed one case of leaf spot (Septoria Ruhi) of raspberry
which was as bad as any we have ever seen on this host.
Forest and shade trees. Because of the articles that have been
written and the great damage it has caused, the chestnut hark
disease is now attracting much more attention in this state than
it has before. It is a question whether this trouble is on the
increase or whether it is merely being reported in new localities
because of the search that has been made for it. We treat of
it more at length in a special paper later in this Report.
The fungus most frequently sent to the station for identifica-
tion during the year was the black spot (Rhyfisma acerinum) of
the maple, and our own observation also showed that it was
unusually common. This fungus is conspicuous because of the
evident black spots, something like finger prints (see Plate
LXIV a), that develop on the leaves. These are slightly elevated
on the upper, and often concave on the lower surface, showing
less prominently beneath. So far as known, this occurs only on
the leaves and does not mature on them until the next spring.
The evident method of combating it is to rake together and burn
the leaves in the fall. While the cultivated cut-leaved variety
of the soft maple is the one most commonly attacked, we have
also found it on the soft and red maples.
The blight of white pine, which attracted so much attention
last year, was very much less conspicuous this year and we
received no complaints of it. Of course last year's leaves which
were killed at the tips still showed the injury, and in some cases
the leaves put out this year also showed the trouble somewhat.
Early in the spring the Forester marked all of the injured young
trees in a certain block at the state plantation at Rainbow. This
block will be watched for a year or two to see if the trouble
spreads and what its effect is on the trees already diseased.
When examined last (fall, 1908), the trouble seemed not to
have spread (at least to any extent) and the marked trees were
improving, the leaves put out this year being usually in much
better shape than those of last year. The results so far seem to
confirm our statement made in the last Report, that this disease
is not primarily due to fungous attack, as believed by some, but
NOTES ON FUNGOUS DISEASES FOR I908. 853
is rather the result of adverse weather conditions which
culminated in the drought of last year.
The sycamore trees, which were severely injured last year by
late frosts in May, just as the leaves were appearing, still show
the effects by their scantier though healthy foliage. Some
writers erroneously attributed this injury to the anthracnose.
B. NEW OBSERVATIONS ON DISEASES PREVIOUSLY REPORTED.
APPLE, Pirtis malus.
Rust, Gymnosporangium macropus Lk. Plate LX a-b. The
aecial stage of this fungus (Roestelia pirata), while common on
apple leaves, has not before been reported on the fruit itself in
this state. In the fall of 1907, Mr. A. B. Cook sent the first
specimen that we have seen. The past year, because of the rust's
imusual abundance, the fruit was also attacked more frequently
than usual. On a roadside seedling near Meriden, in September,
we found it quite abundant on the apples as well as on the leaves.
The peridia on the fruit varied so in the character of their split-
ting open that we thought possibly both of the species of
Roestelia which occur here were present, though the spores
seemed the same. Mr. Kern, however, to whom we sent the two
specimens shown in the halftone, pronounced them the same.
The infected apples showed a progressive development of the
mycelium, so that eventually the whole apple became involved.
Cutting across one of these apples, the presence of the mycelium
was shown by its endochrome, which gave an orange tint to the
invaded tissues. This infected area was always evident at the
surface, narrowing down, in wedge shape, toward the core in
the cross section. Another peculiarity that, so far as we know,
has not been described before, was the development of immature
pycnia within these tissues ; and, in the seed cavities of the core,
the formation, in a number of cases, of perfectly mature peridia.
As these apples offered an easy method of obtaining tissue
containing the mycelium of the fungus free from other germs,
for artificial cultures, attempts were made to grow the fungus in
this way on apple juice agar, but in none of the cultures did the
fungus develop. However, so far none of the rusts have been
grown in such artificial cultures.
854 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
AZALEA, Azalea sps.
Rust, Pucciniastrum minimum (Schw.) Arth. In the Report
of the station for 1903, p. 306, we reported the uredinial stage
of this fungus under the name Pucciniastrum Vacciniorum (Lk.)
Diet., to which it has commonly been referred. Arthur in N. A.
Flora 7^, p. 109, however, considers the rust on Azalea distinct
from that on Vaccinium, and describes it under the name P.
minimum, but states that the telial stage has never been reported.
The past fall we again found this rust on Azalea nudiflora (and
apparently other cultivated species) in the local nursery where
it was seen before, and on specimens gathered the latter part
of October we were able to find the telial stage. The sori of this
stage are so inconspicuous that it is necessary to cut sections of
the leaves in order to be sure of the presence of the spores.
These compound spores are of the normal Pucciniastrum type,
showing (when not too much crowded together) as four cells
in surface view and two cells in longitudinal section. They
occur, one or more, in the epidermal cells of the upper side of
the leaves above the uredinial sori, but sometimes appear to be
situated between the epidermal cells and the cuticle. They vary
in size from 21 to 2^[i, in surface view, to 23 to 29/A in longi-
tudinal section. Their walls are reddish-brown in color. So
far nothing is known of the aecial stage of this fungus, which
is supposed to occur on some coniferous host, and the collections
made by us give no clue to this stage or its possible hosts, though
we have looked for suspicious Peridermia on the Coni ferae in
•that vicinity.
GRAPE, Vitis sp.
Downy Mildew, Plasmopara viticola (B. & C.) Berl. & De
Toni. This fungus is not uncommon on the leaves and green
fruit, but the past year for the first time we have found it here
on the ripening fruit, causing the brown rot described by Scrib-
ner (Fungous Diseases of the Grape, etc., p. 48). In September
specimens of rotting white grapes were sent to the station from
Hartford by Mr. A. H. Newton. An examination showed that
this fungus was responsible for the trouble, though the grapes
were quickly infected by other fungi that fruited on them and
so gave the appearance of being the primary cause of the rot.
NOTES ON FUNGOUS DISEASES FOR I908. 855
On the young green grapes the conidial stage is developed on the
exterior, but with the brown rot of the ripening fruit neither this
stage nor the oospores developed, though the specimens were
examined in all stages of decay, for the latter, until the end of
the season. The characteristic haustoria of the mycelium, how-
ever, easily distinguishes the fungus.
As the mycelium penetrates all through the tissue of the grape,
attempts were made to secure artificial cultures of the fungus,
as we have done with the downy mildews of the potato and Lima
bean, by placing infected tissue in nutrient agar medium in steri-
lized test tubes. In this case we did not succeed, for all the
grapes apparently were contaminated with other fungi that
prevented the development of the mildew, or else crowded it out.
The past )7ear a careful search of grape leaves from different
sources late in the fall disclosed the presence of the oospores
occasionally in these. Farlow years ago reported finding these
spores, but they are rarely found except when a very careful
search is made for them. There is no external indication on the
leaf of their presence, and the only way to find them is to boil
small fragments of the suspected leaves in potash, crushing the
tissues so that they can be examined under the microscope, and
then search until the oospores are discovered. We were most
successful in finding them in the tissue next the larger veins, but
did not find them on the twigs, though they have been reported
on these in France.
Powdery Mildew, Uncinula necator (Schw.) Burr. Plate
LXII c. During September an unusual appearance of this
commoji fungus of the grape was found (in a single variety only,
on the station grounds) where it produced small circular dis-
colorations on the stems of this year's growth, as shown in the
illustration. These reddish spots, about one-quarter inch in
diameter, appeared to be made up of much smaller, closely placed
dots. The fungus in its conidial stage occurred inconspicuously
on these and in time disappeared, so that the cause of the injury
would then have been difficult to determine. The mycelium of
this fungus ordinarily develops externally on the host, sending
only short branches, haustoria, into the tissues for nourishment,
but in this case there is a possibility that the mycelium secured
a firmer foothold in the plant, which might enable it to live over
the winter there.
856 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
PEACH, Prunus Per ska.
Bacterial Spot, Pseudomonas Pruni Sm. Plate LXIX a.
In the Station Report for 1903, p. 337, the writer noted an
unnamed bacterial disease of peach leaves from Pomfret, Con-
necticut, this apparently being the first mention of the disease in
literature. In the Report for 1905, p. 273, a bacterial spot of
plums, causing a purple-black spotting of the fruit, was described
from specimens sent from Bridgeport. This was determined to
be the bacterial disease of plum named by Erwin F. Smith
Pseudomonas Pruni (now called Bacterium Pruni by Smith),
and it was suggested by the writer that these two bacterial
diseases might be caused by the same organism. Recently Rorer
(Mycologia i : 23-7. 1909) has practically demonstrated the
identity of the two diseases, Rorer found the peach trouble
quite common in Arkansas, where it occurred on the twigs and
fruit as well as on the leaves. In this state, on the peach, we
have found the disease only on the leaves, where it causes small
reddish-brown spots which often fall out, producing shot holes,
and when abundant, the premature yellowing and fall of the
leaves. This year it was more abundant and injurious than we
have seen it before. We also received for the first time speci-
mens of diseased plum twigs from Sound View that possibly^
were caused by this organism.
Collar Girdle and Root Injury. Plate LXVIII b-c. In a pre-
vious Report (1904, p. 323) we briefly mentioned winter injury
of the roots of peach trees (Mr. Warner's of North Haven)
caused by the severe winter of 1903-04. The winter of 1907-08
apparently caused more of this trouble — aggravated in part
possibly by a weak condition of the trees due to the 1907
drought — than has yet been reported in the peach orchards of
this state. The trouble was first called to the attention of the
station by Mr. J. H. Hale, who asked for an investigation of
the trouble. Mr. Hale wrote: "There has been a tremendous
dying of peach trees around these parts the past two or three
weeks, after they began to leaf out. Yesterday morning Albert
Carini, who lives in the eastern part of South Glastonbury, came
to me with a tale of practically six hundred dead and dying trees
in an orchard that looked all right four or five days before."
Other growers in the state lost occasional trees, but in few
orchards was the injury so severe as in Mr. Carini's.
NOTES ON FUNGOUS DISEASES FOR I908. 857
In the absence of the writer Dr. Britton investigated this
trouble, and we are indebted to him for the photographs and
notes used here. The examination showed that the diseased trees
had started to develop their foliage, but this soon turned yellow
and dropped off before maturing. Some of the trees by June 2d
had dropped all of their foliage except small tufts at the end
of the twigs, but the fruit still adhered. The trouble was found
to be due to winter injury, which killed the roots and girdled the
bark at the base of the tree, reaching above the ground two or
three inches and forming the so-called "collar girdle." This bark
could easily be peeled off, as shown in the illustration, Plate
LXVIII b, and the demarcation between the injured and living
bark was pronounced. Some indication of injury to the wood at
the girdle was also shown by its brownish color. Some of the
trees were dead only on one side, and in that case the roots were
not all killed or the bark completely girdled ; see Plate LXVIII c.
The trouble at Mr. Carini's was chiefly on one variety, apparently
a tender one, which had been bought for Elberta, but did not
prove true to name.
This injury to peach trees is most likely to occur on places
where the soil is not properly drained, or where the trees are
exposed so that the snow is blown off from the ground around
the trees. The snow acts as a mulch, and is of great value in
protecting the roots and base of the tree. Cover crops or a
vegetable mulch is of similar service where injury of this kind
is likely to occur. Likewise, growers in this state have found
it profitable, especially with young trees, to throw up the dirt
around the base in the fall and then scrape it away again in
spring.
TOMATO, Lycopersicum esculentum.
Chlorosis (Infectious). Plate LXVI b. In the last Report
(1907, p. 362) we mentioned a chlorosis trouble of tomatoes seen
in the field and supposed to be due to the effects of frost, the
plants having been injured by it in the spring. Whether or not
this was the cause we cannot say positively, but attempts to
produce this trouble in young greenhouse plants by exposing
them to the cold so that they were more or less seriously injured
were not successful. The past season we saw this trouble again
in two or three different fields, and by using juice from these
858 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
plants in one case were able to produce the same disease on
healthy tomatoes, and also on tobacco. This shows that this
tomato chlorosis is infectious and of the same nature as the calico
of tobacco. In greenhouse experiments we have frequently pro-
duced chlorosis in tomatoes from juice from calicoed tobacco and
then carried it back to the tobacco again from the tomato. In
one of these experiments (see illustration) the effect on the
tomato was to produce little visible calico, but rather a severe
bacterial-like disease of the tomatoes. This possibly (though we
hardly think so) was of the nature of a burn, since it was worse
in plants sprinkled with water after handling them with the
calicoed juice on the hands to produce the infection. However,
we have at other times seen these small bacterial-like spots both
on calicoed and healthy tomatoes.
C. DISEASES NOT PREVIOUSLY REPORTED.
ASPARAGTJS, Asparagus officinalis.
Smoke (Gas) Injury. Early in October the writer was called
to examine a field of asparagus claimed by the owner to have
been seriously injured some time before (late August or Sep-
tember) by the smoke from an adjacent brick kiln. It seems that
in muggy weather, when the wind was right, the smoke was
sometimes swept down across the field for a time, and the tops
were killed or severely injured. In the previous year such injury
had resulted and the owner of the brick kiln had paid damages
for the same. This year the owner of the kiln claimed that
before the smoke was blown over the field the plants were as
nearly dead as when seen later by the writer. Refusing to pay
damages, he was sued.
After a careful examination, the writer came to the conclusion
that while there was some slight indication of gas injury to the
field (as shown by a streak through the center with more com-
pletely dead tops in an adjacent field), the main injury had not
been caused by the smoke of this year. The asparagus tops in
fields in the near vicinity and elsewhere were in no better shape
than those here at this time, due to the severe droughts of the
year. The asparagus in this field had been very severely ridged,
even for a wet season, and so must have suffered during the
present dry one, which no doubt was largely responsible for the
NOTES ON FUNGOUS DISEASES FOR IQOS. 859
dead roots rather than the gas. As the tops had been injured
the year before by the gas, this no doubt weakened the plants and
made them more susceptible to injury by the drought. This
previous injury, however, had been settled for. It is generally
understood that it is the sulphurous gas in the smoke that causes
injury to vegetation under such conditions.
AZALEA, Azalea sps.
Powdery Mildew, Microsphaera Alni (Wallr.) Wint. The
mildew on this host seemed to confine itself to the under surface
of the leaves, forming there a more or less conspicuous white
coating, with the perithecia scattered. See also New Jersey Tea.
BALM, BEE, Monarda didyma.
Rust, Puccinia Menthce Pers. This forms the II and III
stages, frequently together, as light and dark, very small, dusty
pustules, chiefly on the under side of the leaves, causing more or
less spotting of the upper surface. It was found in a local
nursery in September (rather abundant), on cultivated specimens
of the above host and its variety alha. It is not an uncommon
rust on some of the wild mints, especially the peppermint, Mentha
piperita.
BEAK'S, Phaseolus sps.
Chlorosis {Infections?). Plate LXI a. In the last Report of
the station, 1907, p. 343, a chlorosis trouble of the Lima bean
was described which did not seem to be infectious. (Plate
LXI b of present report.) During September of the past year
certain of the plants of both Lima and string beans on a market
garden farm in Westville showed a chlorosis somewhat different
from that noticed the year before, and which in general appear-
ance resembled very closely the chlorosis (mosaic, or calico)
troubles of tobacco, tomatoes and muskmelons (g. ■z^.). The illus-
tration gives a general idea of this trouble, the tissues around the
veins showing usually the normal green, and those between a
lighter green color, thus giving a mottled or mosaic effect. With
the non-infectious chlorosis of the Lima bean mentioned above,
the lighter green had more of yellowish cast, quite similar to
insect or drought injury. Preliminary experiments in the green-
S6o CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
house, using dried specimens of both Lima and string bean leaves
three months old, soaked in water for a short time which was then
applied to young Lima and string beans, were not successful in
producing this disease, at least not very evidently. Neither did
tobacco water from dried calicoed tobacco leaves produce it,
though such water will easily produce calico in young tobacco
plants. However, these experiments were not extended enough
to say definitely that the disease is not infectious. Experiments
with the fresh juice will be tried later, if possible, as we are
strongly of the opinion that this is an infectious chlorosis.
BEETS, Beta vulgaris.
Drop Dampening-off, Sclerotinia Libertiana Fckl. The
same fungus which caused the drop trouble of parsnips and
lettuce (q. v.) at Farnham's, also caused a serious dampening
off of seedling beets (also somewhat, apparently, of lettuce,
cabbage and radishes) in the hotbeds about the middle of March,
1909. So many of the seedling beets were dampened off that
some of the frames had to be replanted, and in these the seedlings
again dampened off, but not nearly so badly as at first. This
indicates that the extra warm condition of the hotbeds soon after
making was an important factor in the trouble. Also with the
later planting the beds could be aired, when necessary, with less
danger. Unlike the greenhouse conditions, where this fungus
damaged the parsley and lettuce, there was seen little growth of
the mycelium exposed on the soil, probably because there was
little dying vegetation there for its development.
About the time of the second planting, a portion of the bed,
under two frames at the end, was treated with formalin (at the
rate of one part formalin to eighty parts of water, and used at
the rate of two-thirds gallon per square foot of bed). The bed
was left for five days to allow the fumes to escape, and seeded
again with beets. In this treated soil by far the best stand any-
where on the beds was obtained and practically no dampening off
occurred. The only check in this experiment was the adjacent
frames, reseeded eleven days before, where the dampening off
had made the rows quite irregular. One objection to treatment
in this way is that the beds after being made must lie vacant a
week before seeding in order to allow the fumes to escape.
Whether or not the compost used over the manure could be
NOTES ON FUNGOUS DISEASES FOR I908. 861
treated some time before placing it in the beds, and the same
results be obtained, can only be determined by experimentation.
If so, then the beds could be seeded as soon after making as
the temperature allowed.
CHKYSANTHEMTJM (POMPON), Chrysanthemum indicum.
Rust, Puccinia Chrysanthemi Roze. We found this rust not
uncommon on pompons, especially a variety called Sunset, last
October, on outdoor plants in a local nursery; the rust, as on
greenhouse chrysanthemums, formed only its uredinial stage.
These uredinial sori, which occur on the under surface of the
leaves, were, however, somewhat smaller than those on green-
house varieties, but the spores did not appear to be different.
The rust often kills the tissue so that variable-sized, reddish-
brown spots show on both surfaces of the leaves.
DAHLIA, Dahlia variabilis.
Dry Weather Injury. During the past summer there were a
number of complaints of injury to dahHas from some cause.
In the vicinity of New Haven the writer observed that they did
poorly, and the trouble apparently was noticed in other states
than this. The trouble was something like the yellows of asters.
The plants were more or less undersized, and the foliage (less
luxuriant, somewhat misshapen, and turning yellowish at the
margins) frequently slowly died. The plants also flowered much
less than usual, and the flowers were of smaller size and often
one-sided.
A careful examination of diseased plants sent by Mr. H. M.
Robinson of Danbury, who complained that while the trouble
showed somewhat in 1907, it was much worse in 1908, revealed
no sign of any insect or fungus as the cause of the trouble.
Cross sections of the stem under the microscope showed certain
cells of the bark with discolored walls and contents shrunken;
not infrequently lines of these injured cells extended out from
the fibro-vascular bundles toward the surface of the stem. No
signs of fungous threads were found as a cause of these diseased
and dead cells. Everything taken into account, there seems to
be no doubt that the trouble was a physiological one, due to the
dry weather of the early part of the season, mention of which has
862 CONNECTICUT EXPERIMENT STATION REPORT, I907-1908.
already been made. Many of the ornamental plants suffered
from this drought, but more or less recovered during the later,
more moist weather. The injury to the dahlias, however, was
sufficient to severely affect them, especially at the flowering
period. Perhaps the injury may have been slightly accentuated
by injury to the tubers from the drought of the previous season,
in which case the plants the coming season may show the effect
somewhat, even if it proves a favorable season.
DANDELIOIT, Taraxacum officinale.
Leaf Spot, Ramularia Taraxaci Karst. This forms roundish
spots, at first purplish but finally brownish, on the leaves, having
fine concentric rings and often a purplish border. They vary
in size from a pin head to nearly half an inch. While not uncom-
mon on the wild dandelion, it does comparatively little harm to
the cultivated plants, probably because these are renewed each
year from the seed rather than grown continuously from the
roots. There seems to be little or no reason for considering
Peck's species, Ramularia lineola, distinct from this.
GOURD, BOTTLE, Lagenaria vulgaris.
Downy Mildew, Peronoplasmopora cubensis (B. & C.) Clint.
This mildew was seen for the first time last summer, in a West-
ville garden, on this host. It was likewise on the common gourd,
Cucurbita Pepo. In both cases the fungus produced on the
leaves numerous conspicuous reddish-brown spots about one-
quarter of an inch in diameter, which soon ran together. The
fungus showed somewhat as a faint growth on the under surface.
Although a careful search was made on these hosts, as well as on
the numerous varieties of muskmelons in our experimental tests,
throughout the entire season, we were still unable to discover
the oospores, or winter stage, of this fungus.
LAEKSPTJR, Delphinium sp.
Bacterial Spot, Bacillus Delphini Sm. Plate LXIVc.
While we have seen this disease before, we have paid no especial
attention to it, thinking it probably due to injury by sucking
insects. The past summer cultivated specimens of larkspur on
the Experiment Station grounds showed the trouble quite promi-
NOTES ON FUNGOUS DISEASES FOR I908. 863
nently. It is chiefly a leaf injury, developing as purple-black,
irregular spots (evident on both surfaces) which vary from those
scarcely discernible up to a quarter of an inch in diameter, and
where thickly placed, become more or less merged. An exami-
Eiation of the diseased tissue under the microscope showed the
presence of plenty of bacteria. No cultures or inoculations were
made, however. So far as the writer is aware, the only mention
of a bacterial disease of this host is in a short note by Erwin F.
Smith (Science 19: 417. 1904), which is an abstract of a paper
given before the A. A. A. S. A brief account of this disease and
the organism causing it (which is named as a new species), is
given there. Smith produced the disease on various varieties of
Delphinium from pure cultures. In his Bacteria in Relation to
Plant Disease, 1905, Smith also gives a photograph of diseased
leaves.
• LETTUCE, Lactuca sativa.
Drop, Sclerotinia Libertiana Fckl. Plate LXIII. While this
fungus has been known for some time as a serious enemy of
greenhouse lettuce, especially in the great Boston lettuce district
(see Bull. 69, Mass. Agr. Exp. Station, by Stone and Smith),
and no doubt has occasionally done injury to some extent in this
state, we have not previously come across it. In Mr. Farnham's
greenhouse, where parsley {q. v.) was injured by this fungus,
that crop was followed by lettuce without changing the soil.
While some damage resulted to the lettuce, the injury on the
whole was not so great as one might expect, knowing that some-
times as high as ninety per cent, of the lettuce heads have been
killed by this fungus in Massachusetts. However, before setting
out the lettuce, all the refuse containing the fungus was removed
from the soil; the lettuce was frequently cultivated to keep the
fungus from developing on the surface of the soil, and greater
care was taken with watering, especially during cloudy weather.
Out of the whole, only about five per cent, of the lettuce heads
were finally carried off by the drop.
A portion of the soil in this greenhouse shortly before the
lettuce was set out was treated with formalin, rate of one part of
formalin to one hundred of water. This was sprinkled over the
soil gradually until there was used about three-fourths of a
gallon per square foot. The ground was covered with canvas
61
864 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
for a day and then aired for a week before setting the
lettuce. This, however, did not prove long enough for the fumes
to get out of the soil, although it was also lightly spaded three
days before use, and as a result the lettuce began to wilt the
next day, and in less than a week was all dead. We have used
the soil in greenhouse benches inside of eight days after treat-
ment, but as this bed was on the ground itself, it did not dry out
so easily. So it is not wise to use the treated soil under ten
days where plants are set out, or for a week where it is seeded.
The second set of plants, put out a few days after the first were
removed, started off very nicely, and eventually formed the finest
looking lot of heads in the greenhouse. They had a finer green
color, grew somewhat faster and more uniformly, and not a
single one was lost.
Possibly where the sclerotia are present abundantly in the soil,
the formalin treatment would not be so effective. Stone and
Smith found that the use of hot water, heating the soil up to 176°
to 186°, was very beneficial in destroying the fungus and pre-
venting subsequent trouble from the drop. Steam has also been
used for the same purpose.
The trouble is called the drop because the fungus attacks the
base of the leaves, rotting them there and causing them to fall
over. This is shown very nicely by Plate LXIII c, which pic-
tures a check and an inoculated plant. The inoculated plant had
a small amount of the fungus from a pure culture placed on the
base of the leaves that show the drop just two days before the
photograph was taken; at the end of four days all of the leaves
had fallen over, and by the end of the week the plant was entirely
dead.
LILY, COMMON WHITE, Lilium candidum.
Bacterial Spot ? Plate LXIV b. This disease was found on
cultivated lilies during October in a local nursery. The oval
spots are quite conspicuous, the largest varying from one-half
inch to one inch in length. The greater portion of the spot is
occupied by a semi-transparent portion in which the chlorophyll
often entirely disappears, and surrounding this is a smaller
purplish border. In dried specimens one can read print through
the transparent portion if the leaf is placed on the page. The
spots contain numerous bacteria, but also occasionally some
NOTES ON FUNGOUS DISEASES FOR I908. 865
mycelial threads of a fungus, though there was no sign of this
fruiting on the exterior. As yet cultures and inoculations have
not been made, so that it is not positively known that the disease
is of bacterial origin, though from general appearances there
seems to be little reason to disbelieve that it is such. So far, the
writer has found in literature no mention of a similar trouble of
lilies due to bacteria.
MTISKMELON, Cucumis melo.
Chlorosis {Infectious?). Plate LXI c. This physiological
trouble was first seen the past summer on certain varieties of the
muskmelons grown for the station by Mr. Frisbie of Southington.
It appeared first and most prominently on the Extra Early Grand
Rapids. In general, the appearance of the disease is very similar
to the calico disease of tobacco, as the leaves are irregularly
mottled with lighter and darker green areas, the darker green
patches surrounding the larger veins, as shown in the illustration.
The trouble is not severe enough to kill the tissue of the leaves,
and therefore does not very seriously interfere with their normal
functions. Mr. Frisbie said that he had observed this trouble
before on muskmelons. So far as the writer is aware, it is not
recorded in the literature of plant diseases on this host, though
Selby of Ohio has briefly described the same or a very similar
trouble on cucumbers (Ann. Rept. Ohio St. Hort. Soc. 1902: 109.
1903. Ihid. 1903: 128. 1904). In Bull. Ohio Agr. Exp.
Station 156, p. 90, he says : "It seems now that we must class the
mosaic disease of tobacco, the yellows of the peach, peach rosette,
the mosaic disease of tomatoes, and the mosaic disease of forcing
house cucumbers, which the writer has recently investigated at
Ashtabula, Ohio, in one and the same group of maladies."
This disease is very similar in appearance to the calico of
tobacco ; and, as the melons were on land that had recently been
in tobacco, it seemed quite likely that the disease was due to the
same cause. In order to determine if it were infectious, the
writer made a preliminary experiment in the field, similar to
experiments that will produce the calico in tobacco. Some cali-
coed muskmelon leaves were crushed in the hands, and then seven
healthy plants of different varieties at the end of the rows were
handled, and bits of the crushed leaves left on them. Unfortu-
nately, the plants were not examined until some three or four
866 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
weeks later, when all of them showed more or less of the
chlorosis, but as some of the neighboring untouched plants also
showed the trouble it was impossible to say positively that the
disease was induced by the touching in the experimental plants.
Infection experiments will be tried again. The same, or a very
similar trouble, was seen the past year on Lima and string beans
and tomatoes, as well as on tobacco.
HEW JEESEY TEA, Ceanothus americamis.
Powdery Mildew, Microsphaera Alni (Wallr.) Wint. Plate
LXVI a. This mildew was found on French seedHngs of the
above host in a local nursery. There seemed to be considerable
difference as to its abundance on the different plants. It forms
a white coating on both the upper and lower surface of the leaves,
but showing more prominently on the upper. Sometimes this
coating entirely covers the surface of the leaf, as if painted over
with a white paint. In such cases the perithecia often stand out
quite plainly in small circular dark colonies about a quarter of
an inch across, as shown in the illustration. This same mildew
is common on this host here in its wild state. We have reported
it before only on the lilac, but in this Report it is listed also on
the azalea and the Pagoda tree, q. v. Its appearance on these
different hosts varies somewhat.
OAK, Quercus sp.
Limb Gall {Bacterialf). Plate LXV a-b. For a long time
the writer has observed galls on the limbs of various trees, such
as the oak, hickory and maple, but has never definitely known the
cause of these. They vary somewhat in size and duration on the
different hosts, and may not, of course, all have the same causal
agent, though their general character is the same. The general
impression seems to be that these are the results of insect attack,
but Dr. Britton states that the entomologists do not recognize
them as such. The writer, in common with some other botanists,
has believed that possibly they are the result of bacterial action,
and since the researches of Smith and Townsend have shown
that the galls of peach, etc., which in appearance have consider-
able in common with these galls, are due to bacteria, this belief
has been strengthened.
NOTES ON FUNGOUS DISEASES FOR I908. 867
The past winter the Hartford Superintendent of Parks, Mr.
G. A. Parker, sent the writer specimens of the gall on oak, from
Keney Park. Mr. Parker stated that the trouble was first
noticed several years ago on a single tree, and had since slowly
spread over the tree and to two adjacent trees. An examination
showed that the galls varied in size from that of a pea up to a
small-sized pumpkin. There was no evidence of insect work on
them, though other small galls on the twigs were of that nature.
The galls in cross section (see illustration) showed that the
swelling was due to an unusual enlargement of the wood (and
to a less degree, of the bark), and exhibited a semi-radiating
structure from a common center, with black spots showing fre-
quently in the otherwise normally colored wood. The large galls
were apparently some years old, and had increased in size each
year. Some idea of their age could be obtained by cross sections,
though the annual rings of growth were not very distinct. In
the largest knots, not more than ten or twelve of these rings
could be made out, but usually after four or five years the galls
seem to stop growth and begin their gradual decay. The largest
knots had ceased to grow; the bark and wood were both dead,
and the former was more or less decayed also. On the whole,
the oak galls attain a larger size and are more lasting than the
hickory galls, whicli seem to be largely annual, and perpetuate the
trouble by new galls at the margin of the old ones. The surface
of the galls shows a corrugated and rougher character than the
bark of the limbs on which they occur. Unlike the crown gall,
these galls occur on the limbs high up in the tree.
The writer, early in March, made a number of inoculations in
Lima bean agar with tissue from the interior of these galls, but
obtained no growths. Perhaps such growths were prevented by
the tannin-like substance that diffused from the tissues and dis-
colored the medium for some distance around. Possibly cultures
from new galls in the spring might give different results.
OKEA, Hibiscus esculent us.
Powdery Mildew, Erysiphe cichoraceartim DC. This fun-
gus forms a greyish-white, mealy, and rather inconspicuous
growth, in spots, or eventually covering the whole surface, on
the upper sides of the leaves, rarely forming a very slight growth
868 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
on the under surface. Only the conidial stage was found, as is
always the case on the squash, pumpkin, etc., and as this stage
cannot be distinguished from that on those hosts, I have placed
it under the same species. Apparently the powdery mildews do
not occur commonly on the Malvaceae, as Farlow lists only one
host in his Host Index, and Salmon, in his monograph, apparently
only two. Neither gives this host. deThiimen, however, judg-
ing from his description (Grev. 6: 102) described this fungus
under the name Oidium Ahelmoschi, having received it on this
host from Egypt.
PAGODA TREE, Sophora japonica.
Powdery Mildew, Microsphaera Alni (Wallr.) Wint. This
host is a small tree that comes from China and Japan and is
occasionally grown for ornament here. The mildew, apparently,
has not been reported on it before, at least this host is not in
the host indexes of Farlow, Saccardo or Salmon, or in the'latter's
Hosts of Japanese Mildews. It was found not uncommon in a
local nursery, where, in September, it formed a grayish-white
mealy growth, chiefly on the upper sides of the leaves, usually
covering the entire surface of the leaflets. Very few perithecia
were formed. See also New Jersey Tea.
PARSLEY, Petroselinum sativum.
Drop, Sclerotinia Libertiana Fckl. Plate LXIII. In Febru-
ary, 1909, Mr. A. N. Farnham, the market gardener of West-
ville, called my attention to an unusual trouble he was having
with parsley in his greenhouse. The parsley was grown on the
ground in rows, much after the manner of its cultivation in the
field. As the soil is changed each year, hitherto no trouble had
been had with soil fungi, but this year the soil had become
infected in some m^anner, perhaps from the manure used, and
this, with difficulty in properly regulating the watering at the
time the plants were well covering the ground, started the drop
fungus to work in good shape. This fungus develops its sterile
mycelium as a white growth on the surface of the ground,
especially on the decaying vegetation, and also works into the
living stems and leaves, rotting them off. Occasionally it forms
small, black, tuber-like bodies, called sclerotia (see artificial
NOTES ON FUNGOUS DISEASES FOR I908. 869
culture shown in Plate LXIIIb), slightly embedded in these
rotted stems. Where the soil is used year after year this trouble
is likely to become increasingly serious, as these sclerotial bodies
carry the fungus over from year to year, even if the soil thor-
oughly dries out in the summer time. While the fungus in this
case injured the plants so severely as to make an uneven growth,
killing them out entirely in spots, after the first cutting, by
gathering up all the refuse containing the fungus, and by
cultivating the ground frequently and using extra care in water-
ing, the trouble was kept down so that the injury was consider-
ably lessened in the second cutting. This same fungus is often
quite injurious to greenhouse lettuce. A fuller description is
given here under that host, as part of the house was afterwards
planted to that crop.
PEACH, Prunus Persica.
Gummosis. Plate LXVIII a. The branches shown in the
illustration were from a small orchard in Centerville in which a
number of the trees developed this trouble. An examination of
the orchard showed that the wood of most of these trees had been
more or less severely winter injured a few years previously, and
had not been pruned since to start new growth. Apparently the
gummosis trouble was a secondary result of this winter injury,
due possibly to bacteria or fungi that gained entrance to the
branches because of their weak condition and produced diseased
places in the bark, which cracked open and formed a deposit of
gum around the wound. Gummosis has been attributed to a
variety of causes, but we doubt if any particular organism, in the
present case, was wholly responsible for the trouble.
Little Peach. At the " annual meeting of the Connecticut
Pomological Society at Hartford in February, 1908, Mr. C. E.
Lyman of Middlefield called attention to a trouble in his peach
orchard which he took to be little peach. The past season this
trouble has been definitely identified by Mr. M. B. Waite, of the
United States Department of Agriculture, and has been noticed
in other orchards, apparently more abundant than hitherto. As
this trouble is said to be quite serious in Michigan, its appearance
in this state is worthy of careful attention. Little peach was first
investigated in Michigan, by Erwin F. Smith, who found the
870 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
fibrous rootlets of the diseased trees more or less dried up. Mr.
Waite holds that it is a trouble quite similar to the yellows and
that it is contagious, so that infected trees should be promptly
dug up and destroyed. By this means the trouble is said to be
held in check in certain orchards in Michigan. The trees usually
die quicker from little peach (about three years) than from the
yellows.
Concerning this disease Waite (Rept. Conn. Pom. Soc. 1908:
64) says : "The little peach resembles yellows in many respects,
particularly in the foliage symptoms ; and yet certain of its symp-
toms are exactly the opposite, namely, those of the fruit. Fruit
on trees affected by little peach is undersized and belated in
ripening. It is often a week, or two weeks or more belated. Its
size may be only slightly reduced in mild cases, down to little tiny
peaches less than three-fourths of an inch in diameter. Little
peach trees rarely throw the wiry growth. I have only seen it
produced where they were cut back, or on very vigorous young
trees. It is rarely bushy and prominent, as in the case of the
yellows. The foliage characters of the little peach are so nearly
like peach yellows that when the fruit is absent and no wiry
growth occurs, as is frequently the case on yellow trees, it is
impossible to distinguish the two diseases."
The writer is inclined to believe that little peach, like much of
our so-called yellows, is indirectly due to weather conditions,
such as the droughts of 1907 and 1908, and possibly to winter
injury. At least, it has shown up most prominently since the
drought of 1907, and Smith's statement that the fibrous roots of
the trees seem to be injured, goes along very well with the
drought theory. See article relating to peach yellows and
so-called yellows, later in this Report.
POPPY, Papaver sp.
Bacterial Spot? During the past two seasons the writer
has noticed the leaves on poppies in his yard badly spotted from
some cause. These spots are dark reddish-brown, somewhat
watery, irregular, and about one to three millimeters in length,
and usually are quite numerous. An examination of dried
specimens, collected last fall, shows these diseased spots crowded
with bacteria, which appear to be the cause of the trouble. So
NOTES ON FUNGOUS DISEASES FOR I908. 87 1
far no such bacterial disease of this host seems to have been
described, so that before a positive statement can be given,
cultures and inoculations will have to be made.
EADISH, Raphanus sativus.
Spindling. This is a trouble which sometimes appears in
radishes grown in hotbeds, where they have not been watched
closely enough after they germinated. The trouble is due to
too great heat at this time, so that the radishes grow too rapidly,
forming a long slender hypocotyl, often two or three inches above
the ground. Such radishes are largely worthless, and are usually
pulled up and the bed reseeded, as the bottoms of the small
turnip-shaped radish will not form or will be irregular under
such conditions. The way to prevent such trouble is not to use
the beds too soon after making, and to watch them carefully to
see that the temperature is properly controlled by ventilation, so
that the radishes will not grow too rapidly for a time after they
break through the ground.
RHODODENDRON", Rhododendron maximum.
Leaf Spot, Phyllosticta maxima E. & E. This is found
occasionally on leaves, forming reddish-brown areas (often
grayish with flaking away of the epidermis) of greater or less
fetent, usually at the margins or tips. Other fungi sometimes
occur on the spots, so possibly this is not entirely the cause of
the trouble.
SUNFLOWER, ORNAMENTAL, Helianthiis multiflorus.
Powdery Mildew, Erysiphe cichoracearum DC. This forms
a whitish-gray, mealy coating over the upper surface of the
leaves. On these specimens, collected on September 12th, the
perithecia were not present.
Rust, Puccinia Helianthi Schw. This rust was found on the
same specimens with the above mildew, but was confined chiefly
to the under surface of the leaves, the II and III stages showing
as numerous minute, dusty, reddish or blackish outbreaks.
Apparently the rust has not been reported often on this host,
though on the various wild species it is quite common. (See
Report of 1903, p. 361.)
872 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
II. PEACH YELLOWS AND SO-CALLED YELLOWS
General statement. During the seasons of 1907 and 1908
peach trees in Connecticut have shown an unusual amount of
injury variously classed as yellows, so-called yellows, little peach,
collar girdle, winter injury of wood, drought injury, leaf fall,
gummosis, etc. Some persons have been inclined to lump
these troubles largely into so-called "yellows," and others have
made very nice distinctions, especially as to cause, apparently
where such did not exist.
There is no question that there has been an unusual amount of
typical yellows present, such as shown in Plate LXIX b (a
photograph of a peach tree made by Dr. Britton in East Haven
in 1902), and there is likewise no question that much of the.
so-called yellows has not been typical. For instance, many of the
trees cut down last fall as suffering from yellows bore a crop
of peaches of good quality, and often with no indication of the
red streaking in the interior which is taken to be one of the very
first signs of this trouble. What the writer wishes to bring out
in this article is that these various troubles are largely the result
of the unusual weather conditions that have prevailed during the
past seven years. That secondary causes, such as germs and
enzyms, may have afterward entered into the problem and pro-
duced the various dififcrences that show in different trees, is quit^
possible, but these alone we do not believe are to be held
responsible. What have been these weather conditions and their
effects, as shown by our observations covering this entire period,
and of which there can be no question? They are as follows:
Relation of Peach Troubles to Weather.
Winter injury in ipo2. On December 9, 1902, after a very
open fall in which late growing trees had no chance to properly
mature their wood, there came a sudden drop to zero weather.
As a result apple and peach trees in the nursery and those
recently set out in the orchards had their wood prematurely killed
or badly injured. Specimens were sent to the station by nursery-
men immediately after this injury, and the writer also had
abundant opportunity during the next two years to study such
trees in the nurseries and orchards. Such trees showed the
PEACH YELLOWS AND SO-CALLED YELLOWS. 873
normally white wood darkened nearly or quite up to the bark,
but when not too severely injured, the next year a small annual
growth of white wood was formed around this. (See Plate X a,
Rept. 1903.) Trees suffered most that were set out in low
places, and in the nurseries where the trees had been stimulated
to late growth by forcing them with chemical fertilizers and late
cultivation. ,
No one seemed to know much about such a trouble, even
among the nurserymen ; one firm built a large storage shed the next
summer to avoid future trouble to the season's stock. Some of
the least injured of these trees were sold the following year, but
where complaint was made that they died, the nurserymen made
good the loss. In other cases the young nursery trees were cut
back near to the ground and a new trunk started. In some
instances such trees had to be cut back again the next year
because of further winter injury. We have seen two orchards
set out by nurserymen from these twice winter-injured and cut-
back trees which the past year have gone with the so-called
yellows. In one case the trees showed winter injury subsequent
to setting the orchard, and in the other practically none. Now,
we hold the winter injury, the severe pruning back, and the
droughts of 1907 and 1908 as primarily responsible for the
decline of these orchards, rather than yellows.
Severe zvinter of igo^-04. The winter of 1903-04 did not find
the trees so unprepared, because of an open fall, as the previous
year, yet it was so unusually severe that even greater injury was
done. This was especially true in the older orchards. Many
trees were killed outright all over the state. Most frequently the
injury showed in the wood, which was blackened to the snow
line, while the bark and roots were uninjured. Severe injury
of course killed the cambium, and then the trees were past any
help. This injured or prematurely killed wood undoubtedly set
up unusual chemical activities that may have resulted in dele-
terious enzyms or other products that were carried in time to the
new growth. Anyway, after some years I do not find that the
sharp demarcation between the darkened winter-injured wood
and the subsequent growth of normal white wood shows as
plainly as it did at first.
In some places, often depending upon low elevation or
exposure to moist winds, parts of, or even whole orchards, were
874 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
SO severely injured that they were taken up. Many of the trees
least severely injured were severely pruned back and new growth
started. The illustrations on Plate LXVII show two trees that
were severely injured but not pruned back until the early spring-
of 1906; one of the trees failed to respond, but the other made
in three years the vigorous growth shown in the illustration, and
in 1908 bore a fine crop of fruit. Such trees, however, go much
quicker than trees not injured, and where the injury was severe,
even with the help of severe pruning, they have been dying from
year to year, often from yellows or so-called yellows. No one
has disputed the winter injury to the trees that were killed out-
right; but with the trees that have since gone into decline, the
fact that they were thus handicapped has been overlooked by
many who attribute this whole trouble to "yellows."
Subsequent winter injuries. Since the winter of 1903-04 (as,
for instance, in 1906), there has been some further injury, chiefly
to the young twigs and buds, but nothing nearly so severe or
unusual. During the winter of 1907-08, however, winter injury
from collar girdle and root killing was unusually evident,
especially where the ground was not properly drained or where
there was no mulch of snow to protect the base of the trees and
the roots.
Droughts of ipo/ and ipo8. But while these subsequent
winters have not been so severe, certain of the summers have
been, especially the summers of 1907 and 1908, when unusual
droughts prevailed. In 1907 by far the most injury resulted, as
the dry period lasted from June to August, when the rainfall was
less than half that of the average year. In 1908 the drought was
broken by rains in midsummer, which lessened the otherwise
severer injury that would have resulted from the unusual early
and late dry spells.
, After the summer drought of 1907, which at the time showed
its effect on all vegetation, came the moist fall weather, and in
many cases this set up a late growth of the dormant buds on the
peaches. The yellow, curled leaves, due to the drought, and this
premature fall growth of buds, were taken even by some experts
to be the first symptoms of yellows. That such persons were
mistaken in some cases, at least, was demonstrated with certain
nursery trees showing these signs and pronounced typical
yellows, by setting them out by themselves and keeping them
PEACH YELLOWS AND SO-CALLED YELLOWS. 875
under observation the following year, when all trace of the
so-called yellows disappeared. Likewise certain orchards pro-
nounced infected with yellows, the next year under special care
showed decided improvement. There seems to be little doubt
that these dry seasons injured the trees partly through the death
of the fibrous rootlets. We know of one orchard planted with
winter-injured stock and showing subsequent winter injury,
situated on the top of a high, very rocky hill, where all attempts
at cultivation merely increased the loss of water from the soil
during the drought, and where the fibrous rootlets were killed
or severely injured. No wonder this orchard has since dis-
appeared because of the unfavorable environmental conditions
that have surrounded it!
Theories Concerning Yellows.
Winter injury theory. Now from the above we do not wish it
to be understood that we believe that the yellows never can occur
on trees not injured by unfavorable weather conditions. It is
past dispute that it can be budded into healthy trees, and there
seems to be some reason for supposing that it is even contagious,
though no positive proof of this seems to exist. What we do
wish to offer is that seasonal injuries are the starting point and
main factor of these so-called waves of yellows. This is no new
theory. William Saunders, of the U. S. Department of Agri-
culture, writing to Penhallow in 1883 (Bull. Houghton Farm
III, 3: 53) said: "About thirty years ago I came to the conclu-
sion that this disease was one which originated from frost acting
on the unripened wood. I have never known a tree to have the
yellows when placed in conditions where the wood became thor-
oughly ripened before frost, a circumstance, as you are aware,
which never occurs in the Northern States. Any application
which will hasten ripening of the wood, will, therefore, have a
tendency to ward off the conditions which make it possible for
the tree to show yellows. This disease is to be seen on other
plants which are similarly placed, and it was that observation
which first led me to look for the cause of peach yellows in that
direction."
In support of this connection between yellows and winter
injury, we present the following points: (i) The apparent rela-
tion of the present unusual development of yellows, not only in
876 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
Connecticut, but elsewhere, to the very severe and widespread
winter injuries that have occurred to peaches since 1902. (2)
The fact that both winter injuries and yellows come in unusual
severity at irregular periods, and the seeming fact that the waves
of yellows gradually develop some time after these severe
winters, often not reaching full development for some years.
Besides the present case, there seems to have been some relation
between the severe winter of 1881 and the yellows that developed
in New York, Connecticut and Delaware in the following years.
(3) The apparent limitation of yellows to the northern part of
the United States and the mountainous regions in the South,
where winter injury occurs. (4) The fact that the peach is now
a highly developed sensitive plant, as compared with its native
condition, and is grown out of its natural climate, and so is more
likely to succumb to unfavorable environment.
Potash theory. A second theory regarding the cause of
yellows, not now held to any great extent, apparently, was that of
soil exhaustion of the food elements necessary for the best
development of the peach, Penhallow came to this conclusion,
after a careful survey of the subject from all points of view,
basing his belief largely on the chemical analyses of Dr. Goess-
man* of Massachusetts which showed a lack of potassium oxide
in peach yellow fruit and wood. (Jenkins also later reported a
similar result in this state.) Penhallow advocated fertilization
with chemical fertilizers of which muriate of potash is a promi-
nent constituent. The possible lack of potash in the diseased
trees, the general need of fruits for this element, and its easy
exhaustion from the soil, all are facts which are in favor of <"Iie
use of potash fertilizers. Hale and others have found it of
benefit, but Erwin F. Smith's extended experiments (U. S. Dept.
Agr., Div. Veg. Path., Bull. 4. 1893) have shown that it is not
a cure or preventive for yellows, and presumably its depletion in
the soil is not the cause. Perhaps its value can be well summed
up in the words of Hale (Rept. Conn. Bd. Agr., 1891, p. 65),
who said: "My own experience has been that trees fertilized
with muriate of potash and given the same treatment as other
trees to which it was not applied have been freer from the
yellows, have lived longer and produced better fruit, although
* Smith in his paper (Bull. 4) reports analyses at variance , with this
idea.
PEACH YELLOWS AND SO-CALLED YELLOWS. 877
some of them have been diseased, than trees around which potash
in that form was not used at all * * * It is not a cure-all,
but it is to a certain extent a check." A good illustration of the
effect of a potash fertilizer on a peach orchard not in good shape
was shown in the case of one of Mr. Lyman's orchards at Middle-
field the past season. The year before, apparently due to the
drought, the orchard was in such shape that an expert pro-
nounced it an incipient case of yellows. Mr. Lyman gave it a
treatment with saltpeter (potassium nitrate), with the result that
the orchard last season took a decided step forward instead of
backward. Of course if the trouble really was yellows, such
improvement will probably prove of only temporary benefit.
Enzym theory. A third explanation of yellows has been that it
is a physiological disease somewhat of the nature of indigestion,
due to derangement of the chlorophyll of the leaves, as is seen in
variegated plants. Such trouble is thought to be brought about
by the presence of some deleterious enzym in the plant, and it is
this enzym, when carried by budding from diseased to healthy
stock, that causes the yellows to develop in the latter. Smith
(U. S. Dept. Agr. Farmers' Bull. 17: 10. 1894) and Woods
(U. S. Dept. Agr., Bur. PI. Ind. Bull. 18: 22. 1902) were the
first to present this or a similar theory, though they did not
account for the origin of the deleterious enzym. This theory,
modified by the belief that it is the unfavorable weather condi-
tions (winter freezing and summer drought) that are directly
responsible for the development of the injurious enzyms or
toxins, is the theory held by the writer. (See also in Rept. Conn.
Pom. Soc. 1909, Report on Fungous Diseases for 1908.)
Germ theory. The fourth prominent theory to account for
yellows is the bacterial, or germ theory. This was probably first
advanced by Burrill. Smith, in a recent conversation, and
Waite (Rept. Conn. Pom. Soc, 1908, p. 59), also, seem inclined
to this view, though all admit that nothing definite has
yet been found to support it. The chief point in its support is
the supposed, but not definitely proven, contagious character of
yellows.
Preventive Measures.
From the above consideration we may present the following
precautionary measures for the -guidance of Connecticut peach
growers :
878 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
(i) Location. Peach orchards should be planted only in the
southern half of the state, preferably not too close to the Sound.
Along the Connecticut Valley they may extend farther north
than the center of the state. Low lands should be avoided, and
as a rule only the higher hills selected, where the exposure is
such as to avoid as much as possible moist winds in winter and
early development of the buds in spring. Good drainage is
necessary to avoid root injuries.
(2) Inspection. Only the best nursery stock should be used,
free from all suspicion of winter injury or yellows. Winter
injury can be told by the blackened wood. As it is not always
possible to detect yellows in nursery trees, the young orchard
should be watched during the first few years, in order to
promptly remove any suspicious trees, for it is generally supposed
that yellows is contagious. In the bearing orchards, also, any
tree showing signs of yellows should be promptly cut down and
burned. Such trees are of little value anyway, and it is best to be
on the safe side of the question. Such is also the practice of
good orchardists in the best peach-growing districts.
(3) FeHilization. As shown above, potash is a very neces-
sary element for peach growing, and so fertilizers should be well
supplied with it. Care, however, should be used not to force
trees too much, especially with late applications of commercial
fertilizers. This is especially true of sodium nitrate. Such
trees are apt to go into the winter with the wood in an immature
condition, and are then especially subject to winter injury.
(4) Cultivation. Good and frequent cultivation during the
first of the season is very desirable, but after midsummer should
be discontinued, since late cultivation, like late applications of
fertilizers, may prevent proper maturity of the wood. Perhaps
after cultivation is over it will be well in some cases to seed down
the land with a quick-growing leguminous cover crop which can
be plowed under the next spring. This will help to supply the
nitrogen, and also give more or less protection against winter
injury to the roots, especially where the snow blows off or is
lacking. Green (Ohio Agr. Exp. Station Bull. 157. 1904)
found in the study of winter injury to peach trees in Ohio that
where the trees were mulched or protected by crimson clover, or
other cover crops, root injury was much less. A mulch of earth
thrown up around the younger trees in the fall and removed in
the spring also seems to be of value in lessening collar girdle.
CHESTNUT BARK DISEASE. 879
III. CHESTNUT BARK DISEASE, Diaporthe parasitica
Murr.
General statement. In the Report for 1907, p. 345, this
serious trouble of chestnuts was briefly described. The writer
first heard of the chestnut disease in 1905, through an article in
a New York newspaper which discussed a serious disease of
chestnuts in the Zoological Park. Specimens had been sent to
the U. S. Department of Agriculture at Washington for identi-
fication and suggestions for control. Flora W. Patterson
reported it as a species of Cytospora and suggested spraying with
Bordeaux mixture.
A short time later, Dr. Murrill of the New York Botanical
Garden, who has since made an extended study of the fungus
and its havoc, sent the writer specimens of diseased chestnut
bark for his opinion as to the cause. We reported the presence
of a Cytospora, but from our experience with similar fungi at
that time, stated that we believed it might be follojving winter
injury to the trees rather than be the direct cause of the trouble.
Dr. Murrill later found the Cytospora to be the conidial stage
of an ascomycetous fungus which he described as a new species,
Diaporthe parasitica. In his first articles Dr. Murrill noted that
the trouble probably resulted in part from winter injury to the
trees, but later he and all others who have written concerning
the disease lay the responsibility entirely on the fungus.
Through the kindness of Dr. Murrill the writer has several
times visited Bronx Park, where great damage was done, and has
seen something of his experimental work with the fungus.
Forest Park, Brooklyn, was also visited in the fall of 1908, and
a number of localities in Fairfield and New Haven counties, this
state, have been especially examined both by the writer and by
Mr. Hawes. The writer has not aimed to make a special study
of the particular fungus ordinarily associated with the trouble,
as that has already been done very ably by Dr. Murrill (Jour.
N. Y. Bot. Card. 7: 143-153. Je. 1906. Ibid. 7: 203-11. S.
1906. Ihid. 9: 23-30. F. 1908. Torreya 6: 186-9. S. 1906).
However, our extended experience since 1902 with trees of all
kinds which have shown various unusual troubles, due primarily
to seasonal injuries, does not permit us to agree entirely with
62
88o CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
Dr. Murrill, and apparently Mr. Metcalf, that this trouble is due
alone to the fungus Diaporthe parasitica.
General character of the disease. In the vicinity of New York
City the disease took chestnut trees of all ages, the large trees
suffering as much as the younger trees or the sprouts. In most
places there the trouble has now made a pretty clean sweep, so
that few living, or at least healthy, chestnut trees are left. But
as we come over into Connecticut, the injury gradually
diminishes, being as yet serious only in Fairfield County, and
growing less toward its northern and eastern borders. Here,
though many large trees were killed, not all were taken, and as
we go toward its outer limits the damage is only to the chestnut
sprouts and small trees. In New Haven County it seems to be
almost entirely the sprout growth that was injured.
Where large trees are infected, they begin to die from the top,
and their decline is gradual, until the tree is killed to the base.
Whether the roots of such trees are ultimately killed I do not
know, but in one tree examined by the writer at Middlebury,
while the trunk was dead to the ground, the main roots did not
yet show injury. This at least proved that the tree was not
dying as the result of root injury, unless possibly to the very
small fibrous rootlets. Sometimes these dead trees show no
fungus growth, but usually in time there can be found the char-
acteristic orange or chestnut-brown pustules of this fungus
breaking through the cracks of the rough bark, being developed
gradually lower and lower down the tree. The tree dies because
the bark and cambium are killed, but the fungus does not develop
into the wood very deeply.
On the sprout growth and younger trees with smooth bark,
however, the trouble shows much more plainly (see Plate
LXII b) through cankered areas in the apparently healthy bark,
and these frequently completely girdle the trunk or branches. In
late fall and winter the fruiting stage of the fungus shows on
these as small, reddish- or chestnut-brown cushions thickly break-
ing through the bark. It is these cankered areas on the smooth
bark that afford the best evidence that the trouble is entirely due
to the fungus. Such cankered spots, however, usually start from
a winter-killed twig or other injury.
General distribution. The trouble has now made a nearly
clean sweep of the chestnut trees in the New York City and
CHESTNUT BARK DISEASE. 88 1
Brooklyn parks. Dr. Murrill (Bull. N. Y. Bot. Gard. 6: 137.
23 Mr. 1909) says concerning Bronx Park: "All of the chestnut
trees on the grounds have either been killed or seriously damaged
by it." Mr. J. J. Levison, arboriculturist of Brooklyn parks,
writes concerning Prospect Park: "We have removed fourteen
hundred chestnuts, practically all the trees of that species but
six." He also reports (Mycologia i: 36. Ja. 1909) concern-
ing Forest Park that 16,695 chestnut trees were killed in 350
acres of Avoodland there. About seven thousand of these were
over one foot in diameter. Mr. John Mickleborough has also
made a somewhat similar report (Conservation 14: 585-8. N.
1908) concerning the condition of these two parks and else-
where. He estimates the total damage in the eastern United
States as at least ten million dollars.
Metcalf, of the U. S. Department of Agriculture (Bur. PL Ind.
Bull. 121®: F. 1908), gives its distribution as follows: "The
bark disease of the chestnut, caused by the fungus Diaporthe
parasitica Murrill, has spread rapidly over Long Island, where
it was first observed, and is now reported from Connecticut,
Massachusetts, Vermont, New York as far north as Pough-
keepsie. New Jersey, Pennsylvania, and possibly Delaware."
Murrill adds Maryland, and possibly Virginia and Washington,
D. C, to the list.
Distribution in Connecticut. This trouble was first called to
our attention in this state in the fall of 1907 by Mr. F. V. Stevens
of Stamford, Fairfield County, and it is in this county, which is
in the southwest part of the state, next New York and the Sound,
where the chief injury has occurred. The disease has been
found also in New Haven County, which is on the Sound next to
Fairfield, but it occurs here only on the sprout growth, and not
usually doing any serious damage as yet. Outside of these two
counties we do not know of the presence of the disease, as deter-
mined by the examination of specimens, though inquiries have
come concerning it from Willimantic and Pom fret Center, in
Windham County.
Mr. Robert T. Morris (Conservation 15: 226. Ap. 1909)
has recently called attention to the serious damage done near
Stamford and Greenwich, and states that unless soon cut, the
larsre trees will be of little value for lumber. Because of the
882 CONNECTICUT EXPERIMENT STATION REPORT, 1907-I908.
glut on the market, they are of little or no value for cordwood at
present.
In New Haven County the disease has been reported in the
following places : In the vicinity of New Haven the writer has
found only a few specimens, with no damage whatever; — at
Morris Cove, in a low grove, one or two sprouts were found with
large cankers in fruiting condition; in Westville, along Beaver
Creek, a few small trees were found with small cankers in the
otherwise healthy bark, but no fruiting pustules except in one
case. These cankered spots were almost all on the south side
of the trees.
W. A. Henry sent specimens from Wallingford, where he says
that "many sprouts show the disease, though none are yet dead."
We are indebted to Newton J. Peck of Woodbridge for the
specimen shown in the illustration, Plate LXH b. This was on
an eight-year-old sprout tree. Mr. Peck says that only the sprout
growth is affected in Woodbridge, and that he has noticed the
trouble there for four or five years. With Mr. Filley, the acting
Forester, we recently (April, 1909) visited Mr. Peck's woods and
also others in Woodbridge, and found considerable of the fungus
present, but almost all of it on small sprout growth or small trees.
We saw many cankers, often quite small, as yet showing no signs
of the fungus ; and by far the larger part of these were on the
south or southwest side of the trees.
W. M. Shepardson of Middlebury reported the disease in that
region, and the writer on a visit there found the fungus in two
difllerent woods. The situation here threw more light on the
relation to weather conditions. On a dry hill on the Whittemore
estate, many of the trees, oaks as well as chestnuts, showed that
they were not in prime condition, especially their bark. Some
few were dead, and others had dead bark on one side of the tree,
but there was no evidence of the fungus. There is little question
but that here the droughts of 1907 and 1908, especially of the
former year, had seriously injured the trees. On a low spot in
another grove, owned by Mr. Shepardson, over half the trees
were injured or dead. While many of them showed character-
istic Diaporthe cankers, others showed growths of different
fungi, and some had no fungous growth at all ! It looked to the
writer as if winter injury and drought might just as well be
CHESTNUT BARK DISEASE. OS 3
given the responsibility for the trouble here as the bark disease
fungus.
Mr. Hawley, of the Yale Forest School, has reported the fun-
gus common in the woods of the Water Company near Ansonia.
Dr. Graves, of the Yale Bot. Dept., found specimens near the
North Branford line on the road to Twin Lakes. Mr. Metzger
reports a few infected sprouts in his woods at Mt. Carmel. No
doubt other infected regions occur besides. those given.
In Fairfield County, the writer has examined forests near
Stamford and Danbury. At the former place, due to the kind-
ness of P. V. Stevens, the writer and Mr. Hawes, in April, 1908,
got a very good idea of the damage done in one of the most
seriously affected districts in the state. This examination gave
the writer his first evidence of possible relation to winter injury.
In one place chestnut sprouts showing signs of winter injury
(indicated by blackened wood) were found on the border of an
old orchard that also showed the same trouble. In cutting
through the diseased sprouts, nearly all showed this dark wood
back about four years, when the severe winter of 1903-04 did
much damage to trees of all kinds. Of course it is not always
possible after several years to distinguish between winter-injured
wood and the normally colored heartwood, but in our opinion the
dark color of the inner wood of the sprouts (see Plate LXII a)
as seen almost everywhere is too close to and sharply marked off
from the sapwood to be natural.
In order to determine if this disease was contagious, the writer
had Mr. Hawes send Mr. Stevens one hundred small healthy
chestnut trees from the state nursery at Rainbow. These were
set out among the diseased trees late last spring. In a recent
letter Mr. Stevens states that these trees as yet show no sign of
the fungus, and are all living except a few that died when set out.
He also writes regarding sprouts showing the disease: "All the
sprouts from the cut of 1906 were very badly infected, in fact,
seventy-five per cent, of the season's sprouts on our place and
elsewhere in the near vicinity are a total loss, but I have not
found a single sprout of the cutting of the winter of 1907 that
shows the least infection, although I have spent considerable time
looking over the woodlands in our section of the state." This
condition might be explained by the fact that the drought of 1907
884 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
was unusually hard on the sprout growth of that year, or possibly
by the fact that the sprouts of 1908 have had only one season
yet for infection, as compared with two for the others.
At Danbury the writer did not get into the worst infected
woods, but the few diseased trees examined showed chiefly small,
reddish-brown cankered spots on the smooth greenish bark, much
like what winter injury will produce on pear and other fruit trees,
and which Sorauer attributes to winter injury on various trees
in Europe. These cankered spots usually had no fungous growth
on them, and frequently were split through the center, but in
some few cases the injury seemed to have been grown over. In
one specimen brought back, that at the time was taken for the
Diaporthe fungus, it was found on closer examination to be a
species of Discomycetes, a species of Dermatea, as determined
by E. J. Durand. The impression gained here was that these
cankered spots might have resulted from winter injury, as they
were most frequently found on the southwest side.
Mr. Hawes, in his recent forest survey of Fairfield County,
had his assistants, Messrs. Moon and Hodgson, make notes in
each town on the prevalence of the chestnut disease. I am
indebted to Mr. Hawes for the following notes taken from their
reports: "As I" (F. F. Moon) "came eastward from Stamford,
where the effects were the worst, the number of infected trees
decreased and the size and age as well. In the last three towns
(Fairfield, Bridgeport, and Stratford) the infected trees seem to
be almost wholly young sprouts along the road, while chestnut
sprouts in the center of the stand seem to be free from the
fungous disease." The record for the different towns in Fairfield
County is as follows :
Bethel. "Disease spread over whole town and in a good many
cases has done a good deal of damage."
Bridgeport. "A few cases of disease in open grown trees along
road."
Brookfield. "Disease is- scattered over town here and there, but
not doing as much damage as further west."
Danbur3^ "The chestnut bark disease has spread from New
York State into this town, all through its woodlands, and into
adjoining towns. The affected trees are more numerous near the
New York line, but they are in good numbers throughout the town.
Upon examining a good many trees I find that most of the diseased
branches and trees are discovered at a point near a wound, scar,
or crack. In the crotch of two limbs which have slightly cracked
apart seems to be a favorable place for the fungus to enter."
Darien. "The disease has its victims, but not over ten per cent.
show the red branch of distress, and very few are killed."
CHESTNUT BARK DISEASE. 885
Easton. "Disease scattered lightly over most of the town."
Fairfield. "Only small per cent, of trees infected with chestnut
bark disease."
Greenwich. "Disease has infected fully forty per cent, of the
trees, but has not killed many in the town. Most of the trees have
one or two branches affected, but as far as any serious injury is
concerned it does not seem anywhere nearly so grave as in
Stamford."
Huntington. "No chestnut bark disease reported."
Monroe. "Town at present is not badly infested by the disease
except in south central portion, where there are a few very badly
damaged sprout stands."
New Canaan. "Disease found here, but not over ten to fifteen
per cent, of the trees are infected, and these only slightly, not many
dead trees being seen."
New Fairfield. "A few chestnuts along western boundary are
affected with the disease."
Newtown. "Bark disease has appeared only on scattered trees
along western boundary. It is quite certain that the town will be
infected badly with it next year if the present rate of spreading
continues."
Norwalk. "Disease is found here, but not to such a great extent
as further down the coast. It seems to diminish as one comes
eastward. From ten to fifteen per cent, of trees infected. Few
have been cut."
Redding. "Disease is spread over whole town, but is not so bad
in eastern part."
Ridgefield. "Disease has spread over entire town, and in some
cases the trees are infected quite badly, though only a few trees
killed."
Sherman. "Chestnut bark disease appearing in western part of
township."
Stamford. "Estimated that fifty to sixty per cent, of all chestnut
trees in township are infected by chestnut bark disease, and probably
five per cent, killed. Conditions especially bad in northern part of
town."
Stratford. "No signs of any disease barring a few cases of
Diaporthe, which seem to occur chiefly on roadside trees."
Trumbull. "Chestnut bark disease has not as yet done much
damage. Only a few scattered trees noticed that were attacked
by it."
Westport. "Trees infected by chestnut bark disease estimated at
five to ten per cent."
Weston. "Chestnut bark disease is generally distributed over
town."
Wilton. "The disease is found here but not so much of it as in
Stamford. Not over fifteen per cent, of the trees infected, and
not over two or three per cent, killed."
The fungous agent. Whether or not the fungus always
develops its fruiting stage in the cankers the first year, I cannot
state. If it does not, then this fungus, rather than winter injury,
might explain the numerous cankers seen without any fruiting
pustules whatever. On some, however, the small fruiting
cushions or pustules, much like lenticels in appearance at first,
are to be found developing during the summer, but apparently
886 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
not before September does their spore stage appear to any extent.
At first these pustules are light orange-brown, but by winter
become dark chestnut-brown. They are composed of fungous
threads and plant cells. The fungus has two spore stages, both
of which develop in these pustules.
The Cytospora spore stage appears usually during the fall, and
can be found more or less abundant until late spring. In cavities
which appear in these pustules, certain slender fungous threads
produce on their extremities very minute oblong spores in great
abundance. These ooze to the surface, under moist conditions,
as minute tendrils or globules. One can easily see that because
of their enormous production, they would, when washed by rains
over the tree, soon infect it badly, if entrance was readily gained ;
or if carried by insects, birds, or the wind to other trees, how the
disease would rapidly spread.
Usually, along the latter part of December, the second or
winter spore stage reaches its maturity. These spores are
formed in special small spherical receptacles, to be made out with
a hand lens, something like light-colored insect eggs, down in
the tissue at the base of the pustule and around its margin.
These spore receptacles open to the exterior by long slender necks
that run from the receptacle through the pustule. These necks
can be seen as small black specks on the surface, or in cross sec-
tion of the pustule when in their prime. The receptacles are
filled with spore sacs (or asci), and each sac has eight oval to
oblong spores arranged within it, usually in a single row. These
spores are hyaline, and are divided at the center (often slightly
constricted there) by a cross wall into two cells. These spores
are also shed out of the cushions during the late winter and early
spring, so that finally the pustules gradually disappear, leaving
small cavities in the bark.
With care, artificial cultures of the fungus can be obtained by
taking tissue from the inside of cankers in the early stage of
their development. Such cultures of the fungus on Lima bean
agar at first show a growth of whitish threads, but with the
development of the spore stage the growth gradually changes to
a bright orange. The threads form a rather hard crust on the
surface of the medium, and in this the Cytospora fruiting stage
develops as numerous small elevations. The spores, after
maturity, ooze out on the pustules as lemon-yellow drops, which
CHESTNUT BARK DISEASE. 887
later become light chestnut-brown in color. The asco-stage did
not develop, and I believe Murrill has not obtained it in his
cultures on various other media.
The writer has made no infection experiments. Murrill,
however, found the fungus (in his inoculation tests) to be a
wound parasite, but after it once gained entrance it killed the
invaded tissues and eventually the young inoculated trees.
Relation to weather. From the preceding account one can
readily see that the writer believes that the fungus alone is not
entirely responsible for the havoc that has been wrought to the
chestnut trees during the past few years. Winter injury in
1903-04, aggravated by the droughts, especially that of 1907, we
believe to have been important factors in handicapping the trees
so that the way was opened for further serious injury by the
fungus. An account of the unusual weather conditions that have
prevailed here since 1902 is given in the article relating to peach
yellows and so-called yellows. We hold that these winter and
drought injuries have affected chestnut trees as follows:
(i) Probably in some cases trees died outright from winter
killing of the roots. In such cases no sprout growth would
result.
(2) Serious injury occurred to the sapwood, changing it pre-
maturely into heartwood, and thereby greatly reducing the
capacity for carrying water to the leaves. Some sprouts, due to
the droughts, now show only two annual rings of normal white
wood, but most of them four or five, with a sharp demarcation
between the white and colored wood indicating possible winter
injury in 1903-04,
(3) Numerous cankered areas show in the smooth bark
(often without any fruiting stage of the fungus on these
sprouts), and in such cases these are chiefly on the south or
southwest side of the trunk. These cankers often crack open,
offering ready entrance for the fungus. Sometimes they heal
over, or are not deep enough to cause subsequent injury.
(4) Numerous branches and twigs have been winter killed
on otherwise healthy trees.
(5) Injury probably occurred to the fibrous rootlets from the
droughts, especially on rocky knolls and hills, in 1907.
We give below briefly our reasons for believing that weather
conditions are partially responsible for the chestnut disease.
888 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
(i) The chestnut disease was first noticed soon after the
winter of 1903-04. Its appearance was sudden and widespread,
and winter injuries rather than fungous troubles show up in this
way. Since its appearance possibly it has spread further, but
this may be more apparent than real, since discussion of the
disease has caused persons to look for it in places where it was
not looked for before.
(2) This trouble has gone over areas with greater total
destructiveness than any purely fungous disease, especially of
trees, that we have ever seen or heard of, and our experience has
not been a limited one. We have known of winter injuries in
peach orchards, however, just as severe, and both of these trees
are here near their northern limit.
(3) The nature of the fungus is not such as to place it among
the virulent parasitic forms. Murrill found it a wound parasite,
and wound parasites are rarely, if ever, so aggressive as to totally
destroy their hosts. We have seen cankers in apple trees pro-
duced, without doubt, by winter injury in 1903-04, very similar
to the cankers of chestnut. On some of these cankers we found
a Cytospora fungus which at first we thought might have caused
them. We have also found Cytospora fungi on twigs of other
trees killed by winter injury. The genus Diaporthe is made up
almost entirely of saprophytic species, some of which occur on
chestnut. We are not yet sure that Diaporthe parasitica has not
been collected before under some other name. Professor Farlow
calls our attention to the fact that it comes more naturally under
the genus Endothia, and is closely related to E. gyrosa. In
deThiimen's Myc. Uni. No. 769 is a specimen under this name on
Castanea vesca collected by Saccardo in Italy in 1876, whose
Cytospora stage (the only stage showing in our specimen) seems
quite like that of our chestnut fungus. Rehm (Ann. Myc. 5 : 210.
1907) has placed D. parasitica under the genus Valsonectria.
(4) The distribution of the injury shows that the vicinity of
New York City was the center of the trouble, which gradually
lessens in severity as we go away from there and the Sound,
except perhaps, as it heads up the Hudson and Housatonic
Rivers. Now this means either that the disease is spreading
from this center, or that this region, due to soil or atmospheric
conditions, sustained severer injury to the chestnuts during the
severe winter of 1903-04. If due to the former, why, in so
CHESTNUT BARK DISEASE. 889
distant a locality as Woodbridge, New Haven County, where the
disease has been known for four or five years (as long as in New
York) has not the disease spread to the old chestnut trees and
worked similar havoc ?
(5) While of the forest trees the chestnut has suffered far
more than others, especially in the regions indicated, yet in both
Massachusetts and Connecticut during the past few years Dr.
Stone, of the Amherst Experiment Station, and the writer, have
had called to their attention numerous cases of trees killed or
injured, as we believe, by the unfavorable weather conditions
since 1902. Dr. Stone, in a recent letter, says: "All through this
region the winter of 1903-04 caused a great deal of injury to a
large number of trees. The red maples have been dying by the
hundreds here, due to root killing, and I have seen a great many
oaks and large elms four or five feet in diameter injured at that
time, although their death may not occur until three or four years
afterward. It is interesting to note, in the diagnosis of trees,
of which I do a great deal, that the injury can be traced back-
wards four or five years."
The writer has frequently called attention in his previous
reports (Repts. 1903, pp. 280, 303, 324, 328, 341, 351 ; 1904, pp.
312, 323, 326, 327; 1906, pp. 310, 317, 320; 1907, pp. 353, 360)
to winter injuries of apple, grape, Koelreuteria, peach, privet,
white pine, raspberry, and sycamore. In a number of cases
these troubles were afterwards complicated with fungous
growths that to those unacquainted with the conditions would
lead them to beHeve the fungus the only cause of the trouble.
The past year we have also seen numerous red maples, as
mentioned by Stone, that seemed to be dying from the effects of
winter and drought injuries. We do not include the elm here
because it is difficult to determine whether or not the elm leaf
beetle has been entirely responsible for the death of many of
these trees which have died in recent years.
(6) As we showed in a previous article, chestnuts have been
subject to severe injuries of unknown cause in the past, and
have not been annihilated thereby. The cause of their dying was
not made evident at the time.
Future outlook. If the chestnut disease is due alone to the
Diaporthe fungus, as Murrill and others now believe, then it
seems quite likely that Metcalf is correct in his statement that
890 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
unless something intervenes, it means the destruction of all the
chestnuts in the Atlantic States. But both Murrill and Metcalf
are puzzled to explain the sudden and devastating attack of the
fungus. The latter has suggested that possibly the fungus is an
importation from Japan, and that, while it is comparatively
harmless to the Japanese species, on our native species it found
a host upon which it developed with unusual virulence. Murrill,
however, has shown the writer a Japanese chestnut upon which
the disease was as aggressive as on the native species. He
thinks that the fungus is a native species that has by some means
acquired unusual virulence. To the writer neither of these
theories explains the situation so well as the winter-drought
explanation, which is not entirely theoretical, at least.
It means much to the Connecticut owners of forest land
whether or not this disease is due alone to the fungus or is due
in part to seasonal injuries. In the former case they may expect
that they are just beginning to see the results of a devastating
agent. In the latter case, the writer believes that the trouble is
now probably about at the height of its development, so that not
much additional harm may be expected, especially if the follow-
ing summer or two prove reasonably moist and the winters are
normal. No efficacious treatment for the prevention of the
trouble has yet been found, though spraying, pruning and
burning of infected trees have been advocated.
ARTIFICIAL CULTURES OF PHYTOPHTHORA, 89 1
IV. ARTIFICIAL CULTURES OF PHYTOPHTHORA,
WITH SPECIAL REFERENCE TO OOSPORES.
General Consideration.
Previous zvork. The downy mildews (Peronosporales) have
not, to the writer's knowledge, been grown in pure artificial
cultures, with the exception of the genus Phytophthora. Matru-
chot and Molliard of France (Bull. Soc. Myc. Fr. i6: 209-10.
1900. Ann Myc. i: 540-3. 1903) were the first to grow the
potato blight fungus, Phytophthora infesians, in such cultures,
and the writer (Ann. Rept. Conn. Exp. Station, 1905: 317-21)
was the first one in this country to report somewhat similar
results. Jones and Giddings of Vermont (Science 29: 271. F.
1909) have also in recent years been working along this line.
J. van Breda de Haan (Mededeel. Uit's Lands. Plantentuim XV.
1896), according to Matruchot and Molliard, has made cultures
of the mildew of tobacco, Phytophthora Nicotianae, but the
writer has not seen this publication. The writer {loc. cit. p. 296),
at the same time with his work on the potato mildew, also gave
the results of artificial cultures of the Lima bean mildew,
Phytophthora Phaseoli. These references apparently include
most of the work that has been done along this line.
This method of attack admits of a more thorough study of the
life history of these mildews. All of these fungi are supposed
to possess two spore stages in their life cycle, one asexual spores,
conidia, and the other sexual spores, called oogonia. The
oogonia, however, are not usually produced very abundantly or
frequently, and so are rarely found. In fact, for some of the
species they have never been discovered. This has been the case
with the potato mildew; and unfortunately the artificial cultures
did not throw any further light on this stage, as none of the
investigators obtained them. With the Lima bean, however, the
writer, in his first investigations, obtained these spores somewhat
in moderation in the artificial cultures. They had only recently
been found in nature.
The results of the writer in obtaining the oospores of the
Lima bean mildew in artificial cultures, but not those of the
potato, together with other considerations, led him to advance
the theory that with this group of fungi there might exist distinct
892 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
sexual strains of mycelia. In this case it would be necessary to
have both strains of mycelia present for the formation of the
oospores. A somewhat similar condition had been recently
found for certain species of the related group of Mucorales, by
Blakeslee. In our work at that time this phase of the subject
was tried to a limited extent with the few cultures on hand, but
nothing very definite was determined.
In our previous cultural work the media found most successful
for growing these fungi were living plugs of potato, cut by
aseptic methods and placed on moist cotton in a sterilized test
tube; living Lima beans, taken from unbroken pods in the same
way; corn meal, mixed with water or various juices, etc.; and
potato, or pumpkin juice, agar. While the fungi grew on these
media, there were certain drawbacks for each that made it rather
difficult to obtain pure cultures that were easily renewed and
made vigorous growths.
Present work. Last fall we had opportunity to obtain further
cultures of both the potato and the Lima bean mildews, and their
investigation was again taken up with two points chiefly in view ;
viz., 1st, to obtain a perfectly satisfactory medium for their
artificial culture, and 2d, to determine if they possess mycelia of
distinct sexual strains. As another mildew, Phytophthora
Thalictri, on Thalictrum, including its oospores, was found here,
some attention was paid to this in the hope that it might throw
some light on the latter problem. In fact, we have had for con-
sideration all of the species of Phytophthora that are known to
occur in the United States.
Altogether over a thousand cultures of the potato and Lima
bean mildews have been made on various media. The general
results are given under the following accounts of the fungi. By
far the most satisfactory medium, however, is that described
under Lima bean juice agar. With this medium one can grow
either of these fungi, but especially the Lima bean mildew, almost
as easily as any saprophytic fungus. They make a progressive
growth on this medium which often covers the whole surface.
With the Lima bean mildew this growth retains its vitality for
some months, so that cultures are readily renewed at any time.
With the potato mildew the mycelium does not live so long; so
the cultures have to be renewed more frequently, every three or
four weeks, and more care is needed in its renewal.
ARTIFICIAL CULTURES OF PHYTOPHTHORA. 893
As regards the sexual mycelia theory, we have worked from
two points of attack. Our chief efforts have been with the
downy mildew of the Lima bean, to lose the oospores. We have
tried to accomplish this by Petrie dish separation cultures of
the conidia, and by the use of very miinute fragments of the
mycelium from the edge of the cultures. We have not succeeded
in a single instance in permaneiTtly doing away with the oospores
by either of these methods, and in some cases we have tried both
on the culture in hand. With unfavorable media one can tem-
porarily prevent the formation of oospores, but these always
readily develop when the transfer is made to a medium favorable
for their growth. With the potato mildew, we have tried to
produce the oospores by crossing the fungus with cultures from
different sources. While we have had the fungus from only a
few different localities, none of the crosses between these have
given any indication of oospore formation. These results have
thrown very considerable doubt upon the theory of sexual
mycelia.
With the discovery of the oospores in both P. Phaseoli and P.
Thalictri, their continued absence in P. infestans, especially when
the theory of sexual mycelia does not seem to throw light on the
subject, becomes a matter of still greater interest. In our
previous report (p. 323) we gave some of the theories that have
been advanced to explain their absence, of which one was that
this species had lost the power to produce such bodies. Both
Jones and the writer have found, under certain conditions, bodies
in the cultures that possibly may indicate imperfect attempts on
the part of the fungus to produce these spores. It is barely
possible, with the continued renewal of the potato by the asexual
method of propagating it by the tubers that the fungus has like-
wise been continually renewed asexually by its mycelium in these,
and that both (the potato its seeds, and the fungus its oospores)
have thus lost, at least largely, the power to reproduce them-
selves sexually. In this case one would probably find the
oospores only where the fungus developed on the wild species of
Solanum in its native habitat.
Pliytophthora Thalictri Wilson & Davis.
Distribution. This species was first described by Wilson
(Bull. Torr. Bot. Club 34: 392. 1907) from specimens col-
894 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
lected by Davis in June, 1907, on Thalictrum purpurascens, in
Kenosha Co., Wisconsin. Dr. Davis informs the writer that he
has since collected the fungus there and in another locality in the
same state. On October 2, 1908, at Centerville, and again on
October 10, at Westville, the writer found this species on
Thalictrum polygamum in Connecticut. These collections are
apparently the only ones that have yet been made, but from its
occurrence in both Wisconsin and Connecticut it seems very
likely that careful search will reveal its presence in at least the
intervening states.
Life history. Davis did not find the oospores, so Wilson
described only the conidial stage. The mycelium causes black
spots on the leaves, practically like those of P. infestans on the
potato leaves. The conidiophores are produced only sparingly
on the under surface of the leaves. The most important of the
minor differences which Wilson gives as distinguishing this mil-
dew from that of the potato are the shorter and more slender
conidiophores (300-400x5-7^, with" one or two branches), and
slighter smaller and more elongated conidia (20-27 x 1 3-1 7ju,).
The writer found the conidiophores varying from 2^o-^ooix, and
with one to three branches, each bearing one to three conidial
swellings.
The writer was fortunate in finding a few of the oospores
which as yet had not been described. These were formed only
rarely and in moderation in a few of the leaves found at the very
end of the season. Their presence in the tissue could be deter-
mined only upon careful search with a microscope after boiling
the leaf tissue in caustic potash and mashing it apart. Those
seen by the writer did not differ very materially from the
oospores of P. Phaseoli, so that we may expect those of P.
infestans, when found, to be of similar character.
The oospores were not in all cases mature, but they seemed to
have an oogonial wall somewhat more deeply tinted than those
of P. Phaseoli. So far as could be determined, the antheridia
and oogonia were developed from different mycelial threads.
The oogonia are chiefly subspherical, with moderately thin,
reddish-brown tinted walls, loosely enveloping the oospore, and
25-33/^ in diameter. The oospores are spherical, hyaline or
slightly yellowish tinted, with medium thick and smooth wall
(3-4/a) and vary from 18.5 to 25^ in diameter.
ARTIFICIAL CULTURES OF PHYTOPHTHORA. 895
As the Thalictrum does not have any thickened tissues within
which the myceHum penetrates, having so far been found only
in the leaves, it was impossible to obtain artificial cultures of
this fungus after the manner employed with the other two
species.
Infection experiments. Since P. Thalictri resembles P.
infestans so closely, the writer has thought that possibly they
might not be distinct species. Worthington G. Smith (Diseases
of Field and Garden Crops, p. 275-6) gives a list of different
hosts of P. infestans which include even two Scrophulariaceae.
Our specimens were found only at the end of a very dry season,
and were not in very good shape for inoculation tests. At that
time there were no living plants of potato available for experi-
mentation. Tests of the spores on the cut surface of a potato
and on leaves of a young greenhouse tomato failed to give any
results. Some of the infected specimens of Thalictrum were
taken up and placed in a moist atmosphere in the greenhouse,
but the disease did not develop much further. The past spring,
on some of the check plants of Thalictrum, developed pre-
maturely in the greenhouse, the writer failed to produce infec-
tion with spores from artificial cultures of P. infestans, though
these succeeded on the potato. While these experiments were
perhaps not extended enough to speak positively, still they at
least indicate that these fungi are distinct strains, if not distinct
species.
Phytophthora infestans (Mont.) DeBy.
Life history. This phase of the subject, especially with refer-
ence to the conidial stage, has been so thoroughly presented by
DeBary and others that we will not enter particularly upon it
here. Some idea of the character of the conidial stage may be
obtained from the photomicrographs shown in Plate LXXI. In
our former article (p. 304) we made some observations upon
the manner of primary infection in potato fields, which were
somewhat different from the views formerly held. Such obser-
vations as we have been able to make since are still in favor of
this view. If it could be proven that oospores develop in the
decaying seed-tubers, this would further strengthen it. But so
far we have never been able to positively identify oospores in
the tubers under any conditions, though one often runs across
63
896 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
suspicious looking bodies in some of the tubers in the last stages
of their dry decay.
Upon its host in nature this fungus confines its mycelium
largely to the intercellular spaces of the tissues. This necessi-
tates special branches, or haustoria, for penetration into the cells
for the food supply. The haustoria are lacking in the artificial
cultures on agar medium. The mycelium in cultures on living
potato plugs, while invading superficial tissues and cells, does not
penetrate very deeply or set up a special decay. This certainly
suggests that in nature much of the soft rot following attack of
the tubers is due to bacterial action. Often this latter becomes
so bad as to crowd out the original invader. The haustoria
often seem to develop further in storage tubers, or at least their
walls become thickened. This thickening possibly may be due to
an envelope of the plant cellulose. When one sees two of these
knobbed, thickened haustoria within a cell bending towards each
other as if about to conjugate, the impression is gained that this
may be the first step toward the formation of oospores. But,
though we have examined these haustoria carefully, even after
the infected tubers were planted, we have never seen any further
development along this line.
Smith (loc. cit. p. 295) claimed to have discovered the oospores
of the potato fungus. We have tried to obtain specimens of
these from him and others, but have not succeeded. Smith wrote
us in 1906: "No doubt you know that the oospores became a
kind of political subject — oospores of P. infestans or not oospores
of P. infestans? ; and I had no wish to go on. Botanists and
popular writers followed what they took to be the safer authority,
just as Saccardo has done; this is right enough in a way."
Massee thinks that Smith's oospores were the chlamydospores of
a Fusarium, as he writes me : 'T have very carefully examined
W. G. Smith's type slide preparation, and am positively certain
that the so-called oospores are nothing more that the globose,
thick-walled chlamydospores belonging to a Fusarium." From a
study of Smith's drawings and an experience with the flora and
fauna of decaying potatoes the writer is led to the conclusion
that he did not find the oospores of P. infestans; or that, if he
did, he also got other things mixed up with them. Our studies
with the oospores of F. Phase oli and P. Thalictri would also
indicate that those described by him for P. infestans were too
ARTIFICIAL CULTURES OF PHYTOPHTHORA. 897
different to be such. Since his time others, as Smorawski, have
described what they called immature oospores, but the general
belief to-day is that these bodies have not been found.
Our culture work has thrown very little light on this subject.
In some few of the earlier cultures we found occasional bodies
that looked something like an attempt at oospore formation.
Jones recently (loc. cit.) has further studied these bodies, and
has succeeded in producing them in considerable numbers in a
special potato juice gelatine medium. Our impression of those
seen in our own cultures has been that they might be unusual
mycelial branches produced under unfavorable conditions (pres-
ence of certain bacteria, etc.) ; and from what we have seen of
Jones' cultures and slides, they resemble chlamydospores as much
as oogonia. In our experience with the oospores of P. Phaseoli
the oogonia were developed after rather than before the anther-
idia, and in Jones' cultures we saw no signs of antheridia. It is
possible, however, if there really are sexual mycelia, that this
was an attempt of the female strain to produce the oogonia; or,
on the other hand, if this species has lost the power of producing
oospores, such cultures might indicate strains in which this
process had not entirely disappeared.
Cultural methods. In our previous report we described the
method by which cultures are obtained from the mycelium of
infected tubers by taking out this tissue by aseptic methods and
inserting it on cultural media. The chief precautions which have
to be observed are the use of tubers in which the infection is in
its first stages and so has merely tinted the superficial tissue
reddish-brown without any soft rot ; also the sterilized knife used
to take out the infected tissues should be allowed to cool so that
the cut surface is not seared. It is best not to have liquid in the
bottom of the agar culture, or if so, to insert the tissue above
this, as the water may spread bacteria that may be included, and
so spoil the culture. Out of such cultures, at least some with
pure growths, or growths that permit of pure transfers, can be
obtained.
The potato mildew forms its growth more in the air and less
embedded in the medium than the Lima bean mildew. Likewise
the mycelium loses its contents quicker, and so renewal from old
cultures is often unsuccessful. A series of cultures on Lima
bean juice agar, varying from 44 to 64 days old, failed to grow;
898 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
others, from 21 to 34 days old, grew readily, and even in one case
a culture 54 days old grew. It is best, however, to renew the
cultures on this medium at least once every month. The
mycelium in the air easily collapses, so that care has to be taken
in making transfers; especially should the needle be completely
cooled ofif before inserting. Both aerial and embedded material
should be taken, preferably with a sharpened platinum wire, in
these transfers.
Media. Of all the media tried the Lima bean juice agar gave
by far the best results. The fungus on this, if properly started,
formed a luxuriant growth in the air (see Plate LXX a) and
usually a progressive growth, covering the surface of the agar.
This medium likewise proved best for the Lima bean mildew,
and as that mildew formed oospores unusually abundantly in it,
it was thought that the potato mildew might make some effort in
this direction, but there was no more indication of these bodies
in this medium than in those in which the potato mildew grew
poorly. The following notes give the result with the potato
mildew on the various media tried.
Lima bean juice agar (504-10 + 500). While the fungus grew
readily on both the weak Lima and white bean agars (made from
sliced beans and so not as nutritious as when ground), on the whole,
the strong Lima bean agar, as given below, was the most satis-
factory. It makes on this a luxuriant aerial growth of mycelium
and conidiophores, that tends to cover the surface eventually.
Conidia were produced in abundance, but no oospores or peculiar
swollen mycelial branches. One or two drops of lactic acid added
to it usuallv prevented the development of the fungus. See illus-
tration in Plate LXX b A-B.
As this medium has proved by far the most satisfactory for this
mildew and that of the Lima bean, as well as for certain other
fungi, we give our method of making it. We used a 50 -j- 10 -|- 500
formula; that is, 50 grms. of dried ground Lima beans, 10 grms.
of agar-agar and 500 cc. of water. The beans are ground, as fine
as possible with a fruit grinder, and then 50 grms. soaked one-half
hour in tepid water (use as much water as necessary, but of course
not to exceed 500 cc. finally) and then simmered slightly for
another half-hour. Strain off liquid through fine wire strainer, add
agar-agar (better dissolved in small amount of water) and water
necessary to make 500 cc. of medium ; heat long enough to thor-
oughly mix agar-agar and strain again through wire and fine cheese
cloth into test tubes.
Corn meal juice agar (50-I- 10 + 500). This proved a far more
satisfactory medium, as regards aerial growth, for this than for the
Lima bean mildew. In general, it gave results about like those
with potato juice agar; that is, a pure white, aerial growth around
place of inoculation, but not generally progressive. There were no
oospores, peculiar chlam'ydospore-like bodies, or unusual swellings
of the mycelium. See Plate LXX b C.
ARTIFICIAL CULTURES OF PHYTOPHTHORA. 899
Potato juice agar (150* + 10 + 500). This gives a localized but
evident aerial growth, one-half to one inch in diameter around
inoculation. Similar growths on pumpkin juice agar (see Plate
XXV c, Report 1905) were obtained in 1905. Mycelium same as
with corn meal agar. See Plate LXX b D.
Lima bean phaseolin agar ; Nucleic acid peptone sugar agar ;
Phaseolin Pot. Phos. agar; sugar peptone water (see Lima bean
mildew cultures) all proved unsatisfactory, as little or no growth
resulted.
Lima bean juice gelatin (S0-|- 50+ 5oo). Not extensively tried,
but apparently about the same, or a little better, than next.
Potato juice gelatin (150 -}- 50 -|- 500). Very poor medium,
especially for aerial growth. In specially prepared potato juice
gelatin in stab cultures, Jones succeeded with certain strains in
getting the peculiar chlamydospore-like bodies (or immature
oogonia?) spoken of earlier. In our cultures these did not appear
as with him, though certain branches did produce unusual swellings
that had a bacterial-like deposit around them.
Living plugs of potato, etc. As reported in 1905, living plugs of
potato and of pumpkin, especially the former, offer a good medium
for a (usually sparse) conidial growth of the fungus. These plugs
should be on moist cotton. The growth does not cause any soft
decay, though the superficial tissues often turn reddish-brown. The
mycelium does not penetrate very deepl}-, but sometimes invades the
cells. The haustoria are not formed so frequently as in nature.
Jones found considerable difference in the growth on different
varieties. This probably affords a means for testing resistance of
varieties, but I am under the impression that those showing most
resistance will prove to be undesirable varieties, as the less starchy,
soggy ones. (See 1905 Report, Plate XXV a.)
Corn meal (moisten with water or potato juice). In my 1905
tests this proved the most satisfactory medium used, as when
started it favored a luxuriant, progressive growth. The objection to
it is that the corn meal dries out so that it is difficult to get cultures
started, and the medium interferes somewhat with microscopic
examination. (See 1905 Report, Plate XXV b.)
Cross cultures. In order to test the mycelial sexual strain
theory, the writer has from time to time inoculated the above
media with this mildew from different sources. The Lima bean
juice agar affords by far the best one for such tests, as it allows
progressive growths. The usual method has been to inoculate
the bottom of the tube with a culture from one source and above
this — one-half to one inch — with a culture from a second source.
With the Petrie dish (see Plate LXX a) three or four inocula-
tions can be made if extreme care is used against contamination.
Such cross inoculations have been made with cultures obtained
from tubers from several sources in Connecticut, and one each
from Maine, Long Island, Vermont and Holland, the writer
being indebted to Jones for cultures from the last two sources.
*Took 150 grms. peeled potato, thinly sliced, soaked in tepid water, and
then simmered for half-hour, and used juice from this.
900 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
While these cultures have not been extended enough, perhaps,
to speak positively, yet in none of them was there any indication
of an unusual mycelial development or of the formation of
oospores. We have noticed some difference in the vigor of these
growths, as Plate LXX a shows, but this may be due to more
material used in one inoculation than in another, or to the age of
the cultures used, as a culture not frequently renewed tends to
run out.
Hybrid? cultures. Blakeslee found that when certain distinct
species of Mucoraceae were crossed with opposite strains there
was an effort to form the sexual spores. As the Lima bean mil-
dew cultures possessed both of these strains, if they exist, it was
thought that cultures containing both P. infestans and P. Phaseoli
might induce the former to make an attempt at oospore forma-
tion. Certain tubes, therefore, were inoculated with the Lima
bean mildew below and the potato mildew above. Petrie dishes
were also inoculated with the Lima bean mildew in the center and
the potato mildew from several sources around this. Of course
one would expect the Lima bean mildew to produce its oospores
within the area covered by its own mycelium, but at the juncture
of the area covered by the potato mildew one might look for
attempted hybrid oospores if the same condition prevailed as with
the mucors.
At first the writer was inclined to believe that such hybrid
oospores did result. At the juncture of the cultures and within
the area occupied by P. infestans occurred certain immature
oogonia that were larger, somewhat thicker- walled, and of a
darker reddish-brown tint than those produced by P. Phaseoli
under ordinary conditions. One of these doubtful hybrid
oogonia is shown in Plate LXXIV B. In all of these cultures
there appeared in time mature oospores, more or less abundant,
around, in and under the P. infestans colonies, but these were not
different from the oospores of P. Phaseoli. Moreover, the
renewal cultures made from the edge of the P. infestans colonies
on the opposite side of the tube from the P. Phaseoli colony
always gave what seemed to be pure growths of P. Phaseoli.
These results apparently mean that the Lima bean mildew
mycelium being more aggressive, penetrated into the potato
mildew colony and, forming its oospores under somewhat
unfavorable conditions (due to toxins in the medium produced by
ARTIFICIAL CULTURES OF PHYTOPHTHORA. 90 1
the growth of the former mildew), certain of these had been
arrested or otherwise affected in their development, as sometimes
occurs in unfavorable media. The potato mildew mycelium,
being shorter lived, was entirely crowded out by the more
aggressive Lima bean mildew when the renewals were made.
Phytophthora Phaseoli Thaxt.
Life history. In our previous report we gave rather complete
details concerning the life history of this fungus. The general
character of the mycelium, the conidia, and the conidiophores is
shown by the photomicrographs of Plate LXXIII. Such infor-
mation as has been gained during the present investigation has
been chiefly concerning details in the development of the sexual
spores. Due to improvement in cultural methods, we have been
able to produce the oospores in great abundance in artificial
cultures (see Plate LXXIVA). Usually it takes from six to
ten days after the start of the culture before there are any very
evident signs of these bodies, but with a favorable medium, such
as strong Lima bean agar, they then develop very rapidly, so
that practically full-grown oospores can be found in ten to fifteen
days. If the culture gives a progressive growth, different stages
may be found starting from the edge inward, the outermost
growth, of course, being free from them. While the Lima bean
juice agar gives by far the greatest development of oospores, it
is not quite so favorable for their study, because of the usually
abundant aerial growth, as corn meal juice agar. This latter
medium gives a very scanty growth, there being practically no
aerial development. The embedded threads are largely con-
cerned in producing the oospores, which are very slowly
developed, and in old cultures show all stages, most of them never -
reaching maturity.
The first step toward sexual reproduction seems to be the large,
irregular swellings that develop in certain of the threads (see
Plate LXXIVC). We have not been able to determine any
fusion of the mycelial branches that proceeds or accompanies
these swellings, but often they are more or less massed. Very
frequently a terminal swelling develops a normal thread much
like a germ-thread, into which the contents pass, and this may
give rise to subsequent swellings. Such empty swellings in size
902 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
and shape are often quite similar to the antheridia, and perhaps
may be tentative antheridia that fail of full development because
of lack of contact with tentative oogonial branches.
It is impossible in the majority of cases to determine whether
the antheridium and the oogonium come from the same or from
different mycelial branches. In quite a number of instances,
however, we have been able to satisfy ourself that they originated
on distinct branches (see Plate LXXIV J, K) and in some cases
have traced these as independent for some distance. Of course
such branches might originate finally from the same mycelium,
but inasmuch as they remain independent as far as they can be
traced, they admit of the possibility of distinct sexual mycelia.
However, in a few cases (see Plate LXXIV H, I) we have seen
them where they seemed to come from the same thread. Our
results, in failing to permanently lose the oospores, would also
indicate their final common origin.
In the development of the sexual stage, the antheridium is the
first to appear, and is often apparently fully developed before
there is much evidence of the oog'onium (see Plates LXXIV E
and LXXVA). Whether or not the peculiar swellings spoken
of earlier develop into antheridia as a result of contact with
certain other threads or swellings, it is difficult to determine, but
it seems most probable (Plate LXXIV D). This potential
oogonial thread, with or without a swelling, becomes attached
to the base of the antheridium and grows up along its surface
toward the apex. Very often it can be seen when it has only
partially covered the length of the antheridium, as shown in
Plate LXXV B. For a long time it was difficult to decide
whether or not these threads did not actually penetrate the
antheridium and grow through it, and we are not yet certain that
this does' not sometimes occur. Certainly the optical effect is
frequently that of an internal thread with its apical wall very
thin as compared with the side walls, as shown in Plate LXXV A,
B. In time, however, the oogonial thread reaches the top of the
antheridium, and curving around its apex, begins to swell into
the oogonium (Plates LXXIV E and LXXVC), which by this
time is usually cut off from its basal thread by a septum. The
various stages of its enlargement are shown in Plate LXXIV F,
G, H. After the full size is reached the contents begin to be
differentiated, marking off the oosphere (Plate LXXIV G, H)'.
ARTIFICIAL CULTURES OF PHYTOPHTHORA. 903
About this time fertilization by the antheridium usually takes
place, but whether by means of a penetration tube or merely by
a local opening where the walls of the two bodies are in contact,
was not made out. If the oogonial thread really ever penetrates
the antheridium, a union of certain of their protoplasmic contents
no doubt takes place at that time.
After the demarcation of the oosphere by the thin wall, the
subsequent evident change is in the gradual thickening of this
wall until there is formed the fully developed oospore loosely
enveloped by the oogonial sac (Plate LXXIVI-K). These
oospores in cultures vary considerably in size (Plate
LXXVD-G), and often there are a good many that never reach
maturity. They are hyaline or slightly yellowish tinted. We
have made no study of the cytological phenomena that accompany
their formation, but the profusion with which they are developed
in cultures should readily permit such study. We have not yet
succeeded in germinating such spores, as they apparently require
at least a winter's rest before this takes place.
Cultural methods. The Lima bean mildew may be obtained in
cultures by care in selecting beans from pods recently attacked.
It is usually best to use pods showing a fresh and comparatively
slight growth that has barely penetrated into the interior, using
the beans beneath that show little or no sign of attack to the
naked eye. Such beans, if transferred by aseptic means to test
tubes containing moist cotton, will in time give an aerial growth
that is frequently uncontaminated by other fungi or even by
bacteria. From these pure cultures on Lima bean juice agar
can be secured.
In my previous work, the cultures finally ran out, after two
or three months. This was because of contamination, and the
use of poor media for growth. In my recent work, by getting
pure cultures to start with, and the use of a favorable medium
for growth, I have had no trouble of this kind. In fact, the
mildew grows as readily (perhaps a little more slowly) as most
saprophytic forms, and is easily renewed by transfers. In these
renewals, the needle should be cooled after flaming, and then a
quantity of the mycelium and agar should be dug out and
embedded in the base of the new tube. By such means cultures
have been kept growing for over seven months and there seems
to be no reason why they cannot be continued indefinitely.
904 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
The mycelium of the Lima bean mildew lives in these cultures
much longer than that of the potato mildew, probably because of
a more embedded growth in the agar, due to the formation of
oospores, and so the cultures are renewed much easier, and can
be left without renewal for a longer time. A series of trials was
made to determine how old a culture on Lima bean juice agar
could be, and still retain its vitality. In the first test, ten cultures,
varying from 28 to 43 days old, were used. These all grew
readily. Renewals from the same cultures were made when they
varied from 49 to 64 days old, again from these, when 65 to 95
days old, and still again, when 92 to 136 days old; and every one,
except two spoiled by bacteria, made fine vigorous growth, with
oospores in abundance. Renewals from cultures older than 136
days have not been tried, but presumably would be successful.
As the oospores did not germinate, the renewed growth was made
from the mycelium, since the conidia were probably too old for
germination in most cases.
Media. As with the potato mildew, the strong Lima bean
juice agar forms by far the best medium for the growth of the
Lima bean mildew. Not only did the conidial stage develop a
more or less luxuriant aerial growth, but oospores were formed
usually in great luxuriance (see Plate LXXIV A), at the surface
and slightly embedded in the agar. Usually there is no indica-
tion to the naked eye whether or not oospores are produced in
the cultures, but in this medium with certain old cultures, after
the aerial growth had collapsed or when formed less abundantly
than usual, their presence in great abundance could be told by
two or three reddish-brown bands showing somewhat faintly
toward the outer, thinner part of the culture. These darker
bands contained more oospores than the intervening lighter ones.
In general, the oospores were produced more abundantly in the
more nutritious media; also the presence of acid limited or
prevented their formation. The details of the growth of the
fungus in different media is given in the following notes.
Lima bean juice agar (50 -f- lo-j- 500). While on this medium
(Plate LXXIIbB, C) the mildew formed a more or less vigorous
aerial growth of mycelium and conidiospores, it was never quite so
luxuriant as was the potato mildew. Oospores were always
developed in abundance in the strong Lima bean agar, but were not
so numerous in the weak Lima or white bean agar. A progressive
growth of the fungus nearly always occurred on these media, often
covering the surface. With the strong Lima bean agar, even when
ARTIFICIAL CULTURES OF PHYTOPHTHORA. 905
it was apparently made up under about the same conditions, there
was noticed considerable difference in the growth of the fungus on
it. This was probably due to slight variations in the medium
(differences in cooking, sterilizing, etc.) rather than to the fungus,
as it showed most strongly in sets of tubes made at different times.
This variation showed in greater or less luxuriance of aerial
growth, and in greater or less luxuriance of oospore production,
and especially in the banded appearance already spoken of. This
latter usually occurred where less luxuriant aerial but progressive
embedded growth took place above the base of the tube. A cul-
tural medium made from fresh green Lima beans did not prove any
more satisfactory than from the dried beans. The addition of one-
half gram nucleic acid to weak Lima bean agar affected the growth
somewhat unfavorably, often limiting it to a dense, white aerial
development around the inoculation material. This was largely
mycelium, as few conidia or conidiophores were formed, and
oospore formation was almost, if not altogether, prohibited. One
or two drops of lactic acid usually prevented any growth whatever.
Powdered willow charcoal (one teaspoonful to 500 cc. of the
medium) made a black background in striking contrast to the
white aerial growth, but did not seem to affect particularly the
development of the fungus. Cultures of the fungus grown on
white bean juice agar failed to infect young white beans (always
exempt in nature), though the young Lima beans inoculated at the
same time were killed.
Corn meal juice agar (5o-|-io4- Soo). This gave practically no
aerial growth, and but a slight embedded growth, that spread slowly
for a short distance from the point of inoculation. The production
of oospores took place, and because these showed in all stages
(many failing entirely to develop further) and with no aerial
growth to bother, such cultures were well adapted to the micro-
scopical study of the sexual organs, merely by mashing small pieces
of the medium under a cover glass. Plate LXXII b E.
Potato juice agar (150 -|- 10+ 500). The growth differed quite
markedly from that of potato mildew on this medium, as there was
no aerial development. The embedded growth was more evident
than on the corn meal, and consisted of a rather matted develop-
ment of mycelial threads, with very few conidiophores and conidia.
Practically no oogonia were formed, and the few attempted did not
produce oospores. The mycelium did not form irregular swellings
so abundantly as usual, and so was more like that of P. infestans.
Plate LXXII b D.
Sugar peptone agar (4-|- 2+ 10 + 5oo). The fungus failed to
grow, or made only a slight growth around the inserted material,
but with one-half gram of nucleic acid added, it made a somewhat
more evident growth at the point of inoculation. Very few
conidia were formed, and practically no mature oogonia. Phaseolin
Pot. Phos. agar (^ -1- i^ -f- 10 -(- 500) cultures practically failed to
grow. Sugar peptone water (4 -|- 2 -j- 500) failed entirely to grow.
Lima bean juice gelatin (50 -|- 50 -f 500). This is 3. poor
medium, and usually only a slight aerial growth of mycelium and
conidiophores with conidia takes place in surface cultures, and in
stab cultures only a slight development of mycelium, with no
chlamydospore-like bodies. No mature oospores occurred, and
there were few attempts to start these, but the mycelium had more
or less of the swellings. The walls of the imperfect oogonia were
thicker and more strongly tinted than usual.
Potato juice gelatin (1504- 50 -f 500). Similar to, but even
poorer than the preceding, but with no sign of oospore_ production
and mycelium even with few swellings. Surface of medium in time
god CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
becomes darkened in color, due to oxidation, and the conidia, conidi-
ophores and mycelium take on this tint somewhat. There was
no development of the peculiar chlamydospore-like bodies found by
Jones with the potato mildew in his special preparation of this
medium.
Ground Lima beans (with just water enough to keep moist after
sterilization). Used both green and dried beans, and also green
beans with the pods ground with them, but the addition of the
latter proved of no particular value. The fungus formed a rather
luxuriant, fluffy, aerial growth, composed of mycelium and conidio-
phores. Some oospores formed in time in the tissues. On the
whole, not so convenient a medium for study as the agar mediuni.
Plate LXXII b A.
Living Lima beans. These were taken from the interior of
unbroken pods by aseptic means, and placed in sterilized tubes on
moist cotton, and then were inoculated. Or they were taken already
inoculated from the infected pods. Sometimes an evident aerial
growth of mycelium and conidiophores appeared on these, and
sometimes, when the surface was unbroken, no external growth
showed, though the seed coats were discolored by a reddish-brown
dr}^ rot. Oospores were formed more or less abundantly within
the tissues.
Corn meal (with water enough to keep moist after sterilization).
The fungus practically failed to grow in this medium. With our
cultures in 1905, when it was mixed with ground Lima beans and
pods, etc., growths were obtained. The drying out of this medium
in itself often prevents growth starting, and corn meal certainl}' is
not so favorable for this as for the potato mildew.
Attempts to lose oospores. Our cultures of this fungus
obtained last fall were from seven infected beans from the
Experiment Station grounds and a market garden at Westville.
These cultures have been continued distinct ever since. Our
idea in connection with the sexual strain theory had been that
possibly by obtaining cultures of the fungus early in the season,
certain ones might be run across in which oospore production did
not take place owing to the presence of only a single strain.
Last year the mildew did not appear on the Lima bean until the
very end of the season, our first cultures being obtained Sep-
tember 29th. The cultures from these seven beans all produced
oospores. In fact, they have continued to do so ever since,
except when grown under unfavorable conditions.
It being settled that both strains were present, if such existed,
the next attempts were to get rid of one by means of the Petrie
dish separation method with the conidia. It was found by Van
Tiegham cell tests with nutrient agar medium that these spores
did not usually germinate very readily, and when they did it
was by means of germ tubes that did not make a very extended
growth. However, in the poured Petrie dishes from the melted
Lima bean agar tubes, having the introduced mass of spore-
ARTIFICIAL CULTURES OF PHYTOPHTHORA. 907
bearing mycelium shaken through them, it was found that usually
numerous more or less isolated growths started up (see Plate
LXXII a). These usually were so closely situated that they ran
together, so that distinctly isolated colonies, presumably from a
single spore, did not often occur after the first few days of
growth. That these growths, at least sometimes, came from the
germinating conidia rather than fragments of the mycelium, was
shown on microscopic examination of the very young colonies.
From the most isolated of these growths, and as early as possible,
transfers were made to individual tubes. Petrie dish separation
cultures were even made from these a second and a third time,
but always with the result that the oospores eventually appeared
if the medium used was a favorable one. In some cases where
the medium was unfavorable, as potato juice agar, or where it
was made acid, these oospores largely or entirely disappeared,
but they always came back as abundantly as ever when transfers
were made to strong Lima bean juice agar. These results are
very strongly against the theory of distinct mycelial strains, the
chief loophole being that the colonies were never from isolated
spores, which seems quite improbable from the numerous
transfers made from time to time.
The second method employed to get rid of the oospores was
by means of transferring single isolated threads from the edge
of the growth. This fungus does not afford a very good oppor-
tunity for such attempts. However, with the aid of a magnifier,
one can sometimes get very small fragments from the mycelium
that shows slightly embedded on the surface of the agar. Unless
submerged hidden threads extended further than these visible
ones, which seems improbable, it is certain that, in some of the
numerous trials, fragments of a single thread were transferred.
The results with these, however, were the same as with the ordi-
nary renewals, namely, an abundance of oospores on the Lima
bean juice agar.
PLATE LX.
Apple, p. 853.
a. Showing peridia not split open. X 2.
Quince, p. 851.
Apple, p. 853.
?■ 'W-'^'^^V* '^'^^
b. Peridia split open. X 2.
c. Peridia worn away.
RUSTS OF APPLE AND QUINCE.
String Bean, p. 859.
PLATE LXI.
Lima Bean, p. 859.
a. Chlorosis (infectious ?).
b. Clilorosis (non-infectious).
c. Clilorosis (infectious ?) of Musk Melon, p. 865.
CHLOROSIS TROUBLES OF BEANS AND MUSK MELON.
PLATE LXII.
Chestnut, p. 879.
a. Winter injury of wood ?
b. Diaporthe canker.
I I
c. Powdery Mildew of Grape, p. 855. X 2.
DISEASES OF CHESTNUT AND GRAPE.
PLATE LXIII.
a. On parsley refuse, p.
b. Artificial cultures, p.
Check. Inoculated.
c. Showing drop of lettuce leaves two days after inoculation, p. 864.
DROP FUNGUS, Sclerotinia Libcrtiana, OF PARSLEY, LETTUCE, ETC.
PLATE LXIV.
c. Bacterial Spot of Larkspur, p. 862.
DISEASES OF MAPLE, LILY AND LARKSPUR.
PLATE LXV.
a. Showing large galls. Reduced.
b. Showing structure of small galls. Natural size.
LIMB GALL OF OAK, p. 866.
PLATE LXVI.
a. Powdery Mildew of New Jersey Tea, p. 866.
b. Calico from tobacco on tomato and then back to tobacco, p. 857.
SOME DISEASES OF NEW JERSEY TEA, TOBACCO AND TOMATO.
PLATE LXVII.
a. Showing manner of cutting back, spring of 1906.
b. Showing growth made by fall of 1908.
PEACH TREES WINTER INJURED IN 1903-4, p. 874.
PLATE LXVIII.
a. Gummosis, following winter injury, p. 869.
b. Collar Girdle with c. resulting death of tree ;
due to winter injury in 1907-8, p. 856.
SOME RESULTS OF WINTER INJURY TO PEACH.
PLATE LXIX.
a. Bacterial Spot, showing shot hole effect, p. 856.
b. Last stage of Yellows, showing adventitious growths, p. 872.
SOME DISEASES OF THE PEACH.
PLATE LXX.
a. Petrie dish cross cultures from three sources, p. 899.
A 9 8 V C
b. Growths on various media, p. 89S.
ARTIFICIAL CULTURES OF POTATO MILDEW, P/iyfop/it/iora iiifcsfans
PLATE LXXI.
a. mycelium; b. conidiophores; c. conidia. X 600 (about).
DETAILS OF CON I DIAL STAGE OF Phytophthora hifcstaiis, p. 895.
PLATE LXXII.
a. Petrie dish separation culture, p. 907.
u
b. Growths on various media, p. 904.
ARTIFICIAL CULTURES OF LIMA BEAN MILDEW, Phytophthonx I'hascoli.
PLATE LXXIII.
a. mycelium; a', mycelial swellings; b. conidiophores; c. conidia. X6oo(about).
DETAILS OF CONIDIAL STAGE OF Phyfophthora P/iascoli, p. 901.
PLATE LXXIV.
.
'2
H
-c
SI-
-• c
<i--
a. mycelium; b._ potential antheridia ? ; c. antheridia; d. anthcridial tlireads;
e. oogonia; f. oogonial threads; g. oosphere; h. oospores.
X 600 (about) except A.
DETAILS OF SEXUAL STAGE OF Phytopiithora Phascoli, pp. 901-3.
PLATE LXXV.
a. antheridia; b. antheridial threads; c. oogonia; d. oogonial threads;
e. oospores. X 1200 (about); oil immersion; G. stained.
DETAILS OF ANTHERIDIA AND OOGONIA OF Pliyfophlliora /Viasco/i, pp. 902-3.
INDEX.
Page.
Acetanilid 687
headache powders, discussion of analyses of 689
Acetphenetidin 687
headache powders, discussion of analyses of 691
Acetylene 798
Acid phosphate, analyses of 31, 483
Agronomist, report of 397
Agronomy, extension work in 448
Albulac 711
Aleyrodes vaporariorum 806, 815
Alfalfa, yellowing of 850
Allspice IS4, 157
Alsophila pometaria 783, 795
American Agricultural Chemical Co. : —
A. A. C. Co.'s Complete manure with 10% potash 3, 62, 63, 455, 462
Complete tobacco manure.,. 3, 104, 105, 455, 558, 559
Grass and lawn top dressing.. 3, 96, 97, 455, 544, 545
H. G. tobacco manure 3, 10, 455, 462
Southport XX special 3, 58, 59
Superphosphate 3, 68, 69, 455, 520, 521
Tobacco starter and grower. . .3, 88, 89, 100, loi, 455,
540, 541, 554, 555
Dry ground fish 3, 44, 46, 47, 455, 498, 499
Fine ground bone 3, 42, 43, 455, 494, 495
Grass and oats fertilizer 3, 98, 99, 455, 554, 555
Acid phosphate 3, 32, 33, 455, 462
Castor pomace 3, 30, 455, 481, 482
Muriate of potash 3, 36, 37, 455, 488, 489
Nitrate of soda 3, 13, 14, 455, 465
Bradley's Complete manure for potatoes and vegetables. . .3, 86, 87,
455, 544, 545
top dressing grass and
grain 3, 86, 87, 455, 540, 541
Corn phosphate 3, 96, 97, 455, 550, 551
Eclipse phosphate 3, 70, 71, 455, 524, 525
Farmers new method fertilizer. .. .3, 66, 67, 455, 520, 521
Niagara phosphate 3, 72, 73, 455, 524, 525
Potato fertilizer 3, 92, 93, 455, 550, 551
manure 3, 90, 91, 455, 548, 549
9IO INDEX.
Page.
American Agricultural Chemical Co., cont'd —
Church's Fish and potash 3, 64, 65, 455, 522, 523
Crocker's Ammoniated corn phosphate 3, go, 91, 4^, 548, 549
Potato, hop and tobacco fertilizer. .3, 92, 93, 455, 548, 549
Darling's Blood, bone and potash. . . .3, 60, 61, 455, 512, 513, 528, 529
Dissolved bone and potash. .3, 62, 63, 455, 516, 517, 528, 529
Farm favorite 3, 68, 69, 455, 518, 519
General fertilizer 3, 72, 73, 455, 524, 525
Potato manure 3, 88, 89, 455, 544, 545, 554. 555
East India A. A. Ammoniated superphosphate 3, 66, 67, 455, 522, 523
Potato manure 3, 78, 79, 455, 540, S41, S42, 543
Great Eastern General 3, 70, 71, 455, 516, 517
H. G. vegetable, vine and tobacco fer-
tilizer 3, 90, 91, 455, 544. 545
Northern com special 3, 92, 93, 455, 546, 547
Packer's Union Animal corn fertilizer 4, 92, 93, 456, 546, 547
Gardeners complete manure. .4, 62, 63, 456, 514, 515
Potato manure 4, 88, 89, 456, 542, 543
Universal fertilizer 4, 70, 71, 456, 520, 521
Quinnipiac Climax phosphate 4, y2, ^z^ 456, 524, 525
Corn manure 4, 90, 91, 456, 552, 553
Market garden manure 4, 56, 57, 456, 510, 511
Phosphate 4, 64. 65, 456, 518, 519
Potato manure 4, 88, 89, 456, 542, 543
phosphate 4, 90, 91, 456, 546, 547
Read's Practical potato special 4, 98, 99, 456, 554, 555
Standard superphosphate 4, 70, 71, 456, 524, 525
Vegetable and vine fertilizer 4, 86. 87, 456, 546, 547
Wheeler's Bermuda onion grower 4, 100, loi
Corn fertilizer 4, 98, 99, 456, 552, 553
Havana tobacco grower 4, 100, loi, 456, 531, 532, 536, 537
Potato manure 4, 94, 95, 456, 550, 551
Williams & Clark's Americus Ammoniated bone super-
phosphate 4, 68, 69, 456. 522, 523
Corn phosphate 4, 94, 95, 456,
550, 551
H. G. special fertilizer. . . .4, 62, 63,
456, 516, S17
Potato manure 4, 94, 95, 456,
548, 549
Potato phosphate 4, 94, 95, 456, 548, 549
Ammonia water 704, 714
analyses of 706
Anasa tristis 805, 81 1
Ancyhts nubeculana 847
Anisopteryx pomcfaria 267, 778
Anopheles 800, 801, 802, 804
INDEX. 911
Page.
Anthonomus signatus 846
Anthracnose of meadowsweet 352
of string beans 830
of white oak 352
Aphis gossypii 805, 813
pomi 267
Aphis, apple 267
melon 805, 813
squash 805, 814
Apple borer, round-headed 333
brandy, analysis of 712
fruit speck, notes on 340
leaf- folder 847
leaf-miner 267, 768
leaf rust 851
rust 853
scab, notes on 340
spray, injury of 342
Armour Fertilizer Works : —
All soluble 4, 62, 63, 456, 518, 519
Ammoniated bone with potash 4, 68, 69, 74, 75, 456, 522, 523
Bone, blood and potash 4, 58, 59, 456, 512, 513
Complete potato 4, 90, 91, 456, 552, 553
Corn king 4, 86, 87, 456, 532, 546, 547
Fish and potash 4, 60, 61, 456, 522, 523
Fruit and root crop special 4, 78, 79, 456, 542, 543
Grain grower 4, 88, 89, 456, 552, 553
High grade potato 4, 82, 83, 456, 542, 543
Market garden 4, 58, 59, 74, 75, 456, 514, 515
Bone meal 4, 42, 43, 456, 494, 495
Artificial color in catsup 129
Ashes, analyses of lime-kiln 114, 115, 567, 568
miscellaneous 568
from household fires, composition of 566
of rice hulls, analysis of 117
Asparagus, injury of, bj'^ smoke 858
Assassin bug 822
"Available phosphoric acid," explanation of term 33, 483
Azalea, powdery mildew of 859
rust of 854
Bacillus Delphini 862
Bacterial spot of larkspur 862
peach 856
lily 864
poppy 870
Bacterium pruni 856
tumefaciens 344
64
912 INDEX.
Page.
Bag-worm 337
Baker, H. J., & Bro. :—
Baker's Castor pomace 4, 30, 456, 481, 482
Baldwin spot, notes on 340
Balm, rust of bee 859
Banding trees 792-794
Barley products 726, 754, 755
Barnyard, analysis of wash from 569
Basic slag 34
Bean, chlorosis of Lima 343
Beans, chlorosis of 859
Beef, wine and iron 673
analyses of 676-679
claims of manufacturers of 682
discussion of analyses of 680
methods of analysis of 685
volume and selling price of 675
Beet pulp 175, 733
refuse, analysis of 568
Beetle, a fungus-inhabiting 337
Beets, dampening off of 860
Bellflower, rust of 343
Benzoic acid in catsup 129
Berkshire Fertilizer Co. : —
Berkshire Ammoniated bone phosphate 4, 72, 73, 456, 524, 525
Complete fertilizer 4, 62, 63, 456, 514, 515, 516, 517
Grass special 4, 84, 85, 456, 544, 545
Long Island special 56, 57, 456, 514, 515
Potato and vegetable phosphate . .4, 96, 97, 456, 550, 551
Tobacco special 4, 82, 83, 456, 530, 538, 539, 544, 545
Fine ground bone 4, 41, 42, 43, 456, 494, 495
Bitter rot of currant 347
Bittersweet, crown gall of Japanese 3-44
Blackberry, rust of 344
Black potash, analysis of 487
Blight of pine 353
Board of control, report of ix
Boardman, F. E. : —
Boardman's Complete fertilizer 4, 56, 57, 456, 510, 511
Bohl, Valentine: — . .
Self-recommending fertilizer 4, 42, 43, 456, 494, 495
Boletotherus hifurcus 337
Bone black, analysis of 120
manures 39, 491
guaranties of 41, 493
analyses of 42, 43, 494, 495
cost and valuation of 41, 493
INDEX. 913
Page.
Bone, method of valuation of 40, 493
Borax 710
Borer, maple 336
poplar 335
round-headed apple 333
Botanist, report of 339, 849
Bowker Fertilizer Co. : —
Castor pomace 5, 30, 456, 481, 482
Muriate of potash 5, 36, 37, 456, 488, 489
Nitrate of soda 5, 13, 14, 456, 465
Bowker's Acid phosphate 4, 32, 33, 457, 483, 484
Complete alkaline tobacco grower 4, 104, 105, 457,
558, 559
Corn phosphate 4, 100, loi, 457, 554, 555
Early potato manure 5, 90, 91, 457, 546, 547
Farm and garden phosphate 5, 72, 73
Fine ground fish 5, 44, 47, 457, 498, 499
Fisherman's brand fish and potash 5, 68, 69, 457, 520, 521
Fresh ground bone 5, 42, 43, 457, 494, 495
Gloucester fish and potash 5, 72, 'j'i, 457, 526, 527
Hill and drill phosphate 5, 66, 67, 457, 524, 525
Lawn and garden dressing 5, 100, loi, 457, 554, 555
Market garden fertilizer 5, 64, 65, 457, 520, 521
Middlesex special 5, 70, 71
Potato and vegetable fertilizer 5, 94, 95, 457, 550, 551
Potato and vegetable phosphate ... 5, 98, 99, 457, 554, 555
Pure unleached Canada hard wood ashes 5, 112, 113,
457, 462, 564, 565
Sure crop phosphate 5, 72, 73, 457, 526, 527
Tobacco ash elements 5, 104, 105, 457, 558, 559
starter 5, 90, 91, 457, 548, 549
XX bone 5, 42, 43, 457, 494, 495
Stockbridge Special complete manure for corn and grain . .5, 86, 87,
457, 540, 541
Special complete manure for potatoes and
vegetables 5, 88, 89, 457, 540, 541
Special complete manure for top dressing and
for forcing 5, 84, 85, 457, 538, 539
Tobacco manure ■. .5, 82, 83, 457, 538, 539
Brainard, H. K. : —
"High Grade" 5, 56, 57
Brewers' grains, dried 177, 204, 205, 727, 754, 755
Brown-tail moth 313
new law regarding 308
Buckwheat flour 127
Buckwheat products 175, 202, 203, 726, 754, 755
914 INDEX.
Page.
Buffalo Fertilizer Co. : —
Buffalo Tobacco producer 5, 78, 79, 100, loi, 457, 462
Celery and potato special 5, ^^, 96, 97, 100, loi, 457, 540, 541
Farmers' choice 5, 48, 49, 50, 72, 73, 457, 514, 515
Fish guano 5, 70, 71, 457, 512, 513
Garden truck 5, 48, 49, 50, 62, 63
H. G. manure (or fertilizer) 100, loi, 457, 501, 512, 513
Ideal wheat and corn 5, 76, 77. 96, 97, 457, 538, 539
Top dresser 5, 48, 49, 66, 67, 72, 73, 457, 510, 511
Vegetable and potato 5, 76, TJ, 94, 95, 98, 99, 457, 538, 539
Bone meal 5, 41, 42, 43, 457, 494, 495
Floats 486
Acid phosphate 483, 484
Muriate of potash 5, 36, zi, 488, 489
Nitrate of soda 5, I3, I4
Butter and butter substitutes 162, 713
Cabbage butterfly 768
maggot, treatment to prevent 832-83^
Caeoma Abietis-Canadensis 350, 389, 390, 391
Abietis-pectinatae 389
Calosoma calidum 786
scrutator 786
Calyptospora columnaris 393
goeppertiana 385, 391
Canker worm 769, 777-796
description 782
fall 783
spring 782
natural enemies 786
postal card bulletin on 767
remedies 786-792
summary 794
Carbon disulphide 797
used against peach sawfly 292
for fumigation 272
tetrachloride 798
used for fumigation 275
Carum copticum, analysis of 733
Castor pomace, analyses of 30, 481
Catarrh remedies 714
Catsup 129
Cercospora Dolichi 346
sordida 362
Chestnut bark disease 345, 852
character of 880
distribution in Connecticut 881
future outlook 889
INDEX. 915
Page.
Chestnut bark disease, general distribution 880
general statement concerning 879
relation to weather 887
the fungous agent 885
trees injured by beetles 845
Chili sauce 129, 713
Chionaspis pinifoliae 335
Chlorine, used for fumigation 277
Chlorosis of bean 343, 859
muskmelon 865
tomato 857
Chocolate 134, 713
compound 135
sweet 135
Chrysanthemum, rusted 86x
Chrysobothris femorata 333
Chrysomyxa Abietis 389, 391
albida 383, 385
Pyrolae 3^
Chrysopa sp ' 822
Cinnamon IS7
Clark Seed Co., Everett B. : —
Clark's Special mixture for general use 5, 54, 56, 57, 457, 500, 501,
510, 511, 512, 513
Special 10% brand 60, 61, 457, 510, 511, 526, 527
Clover worm, green 769, 828
description 830
remedies 832
Cloves 155- 157
Cocoa 134
Coe-Mortimer Co. : —
Genuine Peruvian guano, Chincha grade 6, 60, 61, 457, 500, 508, 514,
515, 528, 529
Lobos grade 6, 60, 61
Gold brand excelsior guano 5, 50, 66, 67, 457, 518, 519
H. G. ammoniated bone superphosphate 5, 70, 71, 457, 516, 517
Peruvian market garden fertilizer 6, 48, 50, 68, 6g
Peruvian tobacco fertilizer 6, 75, 84, 85, 88, 89
Tobacco and onion manure 457, 538, 539
E. Frank Coe's Celebrated special potato fertilizer 5, 94, 95, 457,
536, 537
New Englander corn and potato fertilizer 5, 98, 99,
457, 550, 551
Peruvian vegetable grower 6, 50, 62, 62, 457, 536,
537
Red brand excelsior guano 5, 48, 50, 64, 65, 458,
512, 513
91 6 INDEX.
Page.
Coe-Mortimer Co., cont'd —
E. Frank Coe's XXX pure ground bone 6, 42, 43, 458, 494, 495
H. G. sulphate of potash 488, 489
Acid phosphate 483, 484
Muriate of potash 488, 489, 490
Nitrate of soda 13, 14
Tankage 496, 497
Cofifee 137, 713
hygienic 141
Coleosporium Campanulae 343, 374
Helianthi 394
Senecionis 394
Solidaginis 375, 376
Vernoniae 380
Commercial feeds, average composition, digestibility and selling
price, 735
Commercial feeds, containing weed seeds 736
Connecticut Fat Rendering and Fertilizing Corporation: —
Tankage 6, 41, 45, 458, 496, 497
Connecticut Valley Orchard Co. : —
C. V. O. Co.'s H. G. special ...6, 56, 57, 74, 75, 458, 508, 510, 511,
526, 527, 528, 529
Contents, table of v
Cooper's Glue Factory, Peter : —
Pure bone dust 6, 42, 43, 458, 494, 495
Coi-n and oat feeds 178, 204, 205, 728, 754-757
breeding at present in progress 400
practical use of Mendelism in 407
ear-worm or boll-worm 847
Corn, caring for seed 401
dent-sweet crosses 41 1
flint-dent crosses 41 1
flint-sweet crosses 410
germination tests 403
inbreeding of 419
inheritance of characters in 407
oats and barley 179, 206, 207
prospects for better seed 397
purple-white crosses 413
purchase of seed 405
red-white crosses 415
summary of law of inheritance 416
yellow-white crosses 412
Corrections and additions xxiii
Cotton hull ashes, analyses of 109, 560
"Cotton hulls," analyses of charred no
Cotton seed meal IS, 169, 192, 193, 466, 717, 742, 743
INDEX. 917
Page.
Cotton seed meal, composition and value of 19, 469
guaranties 18, 468
standard classification of 16, 467
tables of analyses of 22-29, 470-480
Cow pea, leaf blight of 346
Cream, analyses of 162, 712
Cream of tartar 138
Creatin, method of determining 614
Creatinin, method of determining 613
Cronartium asclepiadeum 382
Comandrae 394
Comptoniae 353, 380
ribicola 394
Crown gall of bittersweet 344
Cryptorhynchus lapathi 335
Cucumber beetle, striped 805, 807
Culex 800, 801, 802, 804
Curcurbits, insects attacking 805
Currant, bitter rot of 347
powdery mildew of 348
Currant worm 768
Cuterebra ciiniculi 338
Cylindrosporium Filipendulae 352
Dahlia, dry weather injury of 861
Dairy and stock feeds, proprietary 180, 206-209, 729, 756-759
Dampening off of beets 860
sweet pea 359
Dandelion, leaf spot of 862
Dennis, George L. : —
Bone 6, 42, 43, 458, 494, 495
Diabetic flour, analyses of , 712
foods 138, 71 1
Diabrotica xii-pimctata 805, 809
vittata 805, 807
Diaporthe parasitica 345, 879
Dissolved rock phosphate, analyses of 31, 483
Distillery grains, dried 176, 202, 203, 726, 754, 755
Downy mildew of gourd 862
grape 854
Dried blood, analyses of 15, 465
brewers' grains 177, 204, 205, 727, 754, 755
Drop of lettuce 863
parsley 868
Drugs, summary of results of examination of 715, 716
Eldredge, T. H. :—
Eldredge's Special fish and potash fertilizer 6, 70, 71, 458, 524, 525
superphosphate 6, 72, 73, 458, 524, 525^
9l8 INDEX.
Page.
Elm leaf beetle 337, 767, 769, 815-828
description 818
natural enemies 821
outfit for spraying 825
remedies 823
summary 827
Ennomos subsignarius 842
Ensilage, analyses of maize 721
Entomological features of 1907 267
1908 768
Entomologist, report of 266, 763
Epilachna borealis 805, 810
Eriophyes pyri 770
Erysiphe dehor acearum 867, 871
Polygoni 349
Essex Fertilizer Co. : —
Essex A I Superphosphate 8, 72, 72
Complete, potatoes, roots and vegetables 8, 80, 81, 458, 530,
546, 547
Corn, grain and grass 8, 82, 83, 458, 531, 548, 549
Grass and top dressing 8, 80, 81, 458, 532, 550, 551
Market garden and potato manure ...8, 92, 93, 458, 552, 553
Special tobacco manure 8, 78, 79, 458, 540, 541
Tobacco starter 8, 90, 91
and grower 458, 548, 549
XXX fish and potash 8, 64, 65, 458, 520, 521
Dry ground fish 8, 44, 47, 458, 498, 499
Ground bone 458, 494, 495
Estigmene acraea 843
Eumenes fraternns 786
Euproctis chrysorrhaea , 313
Euvanessa antiopa 267, 768
Fall canker worm 267
Feeding stuffs, digestibility of 183, 735
explanations of analyses of 166
law regulating sale of 165
sampling of commercial 166
uses of analyses of 168
weight of one quart of various 189, 762
Fern, leaf scorch of 349
Fertilizer elements, trade values of 39. 49-2
law, observance of 2, 454
Fertilizers, analyses of ii, 463
classification of 12, 464
duties of manufacturers and dealers i, 453
method of valuation of 39> 49i
on which analysis fees have been paid, list of — 3, 455
INDEX. 919
Page.
Fertilizers, sampling and collection of 10, 462
selection and purchase of commercial 52, 503
Fish, analyses and valuations of 46, 500
of dry ground 44 47, 496, 499
guaranties of 46, 498
Flax feed and flax flakes 179, 206, 207, 727, 756, 757
Floats, value of 485
Food products, summary of results of examination of 715, 716
work in 1907 163
1908 715
Forester, report of 211
Forest plantations 211
in Conn, older 251
recent 242
private 248
planting experiments, description of 213
map of 228
summary of 230
visitor's guide to 228
plantings by educational institutions 246
Forests, state 242
Frisbie, L. T., Co. : —
Frisbie's Fine bone meal 6, 42, 43, 458, 494, 495
Fruit preserves 581
Fumigating nursery stock for San Jose scale 796
with gases, tests 270
Fungous diseases, of 1907, notes on 339
of 1908, notes on 849
Galerucella liiteola 337, 815
Gases for fumigation, tests of 270
Germof ert Mfg. Co. : —
Germofert Patented fruit and flower fertilizer 458, 534, 535
General fertilizer 458, 512, 513
Vegetable fertilizer 458, 534, 535
Natural plant food 528, 529
Ginger 156, iS7, 7I3
ground 574
Gloeosporium canadense 352
nervisequum 360
ribicoluni 348
Ribis 347
rufo-maculans 347
Gluten feed 172, 198-201, 722, 748-751
acidity of 723
artificial color in 722
meal, analysis of 118
Golden-rod devoured by beetles 844
65
920 INDEX.
Page.
Goodsell. W. O. :—
Special grass mixture 458, 532, 534, 535
Gourd, downy mildew of 862
Grape, downy mildew of 854
powdery mildew of , 855
Grape vine flea beetle 337
Gummosis of peach 869
Gymnosporangium clavipes 351
macropus 853
Gypsy moth, control work 300
funds for work 307
Gypsy moth in Connecticut 7^7
infested localities near Connecticut 776
legislation concerning 307
in other states 310
new law regarding 308
parasites 311
present condition at Stonington 776
scouting for egg-masses — Eastern Connecticut 774
Hartford 774
New Haven to Hartford 775
Stonington 773
statistics 306
suppression work 77^-777
funds 77^
summary 777
Halisidota caryae 332, 843
tessellaris 843
Haltica chalybea 337
Headache powders 7^4
analyses of 692-705
preparations 686
methods of analysis of 688
Heliothis obsoleta 847
Hemlock, rust of 350
Heterocampa guttivitta 848
Heteroecism 370
Hickory tussock caterpillar 842
moth 332
Home mixtures 107, 559
analyses of 106, 107, s6o, 561
Hominy feed I74, 200-203, 725, 750-753
Honey I39, 162
compound I39
Hops, analyses of spent 733
Horse feeds, proprietary 180, 206, 207, 729, 756, 757
"Humus Fertilizer," analysis of 570
INDEX. 921
Page.
Hydrocyanic acid gas, used for fumigating 280
Ichneumon utilis 786
"I. M. P. Plant Food," analysis of lig
Indigo, powdery mildew of false 349
Infant and invalid foods, methods of analysis of 601
tables of analyses of 602-605
foods 599
Insect notes 842
notes, miscellaneous 334
Invalid foods 599
Iodine, tincture of 707, 714
Ithycerus noveboracensis 845
James, Ernest L. : —
James' Bone phosphate 6, 74, 75, 458, 526, 527
Ground bone 6, 42, 43, 458, 494, 495
Jams 581
and jellies, the labeling of compound 582
Jellies 581
Jelly powder 583
Julus hortensis 337
June berry, rust of 351
Kainit, analyses of 38, 490
Kelsey, E. R. :—
Bone, fish and potash ..6, 56, 57, 74, 75, 458, 509, 510, 511, 526, 527
"Kill-o-Scale" 282
Kuehneola albida 344, 372, 383, 384, 385
Lard 143
compound 144
Larkspur, bacterial spot of 862
Laurel, leaf spot of 351
Laws regarding foods and drugs 121
Lead arsenate ySj, 823
Lead arsenate, analyses of 323
chemical composition of 321
vs. Paris gi-een 843
Leaf blight of cow pea 346
trumpet-creeper 362
scorch of fern 349
spot of dandehon 862
laurel 351
rhododendron 871
Lehia grandis 844
Lema trilineata 844
Lemon extract 144, 713
Leopard moth 847
Leptinotarsa decemlineata 768
Lettuce, drop of ^ 863
92 2 INDEX.
Page.
Liebig process for meat extract 606
Lily, bacterial spot of 864
Limb-gall of oak 866
Lime, analyses of 114, 115, 567, 568
carbonate of 567, 568
Lime and sulphur washes, various kinds 840
Linseed meal 170, 192, 193, 718, 742, 743
analysis of 31
Lister's Agricultural Chemical Works : —
Lister's Ammoniated dissolved bone phosphate 6, 64, 65, 458, 514, 515
Potato manure 6, 82, 83, 458, 530, 531, 538, 539
Special corn 6, 86, 87, 458, 552, 553, 554, 555
potato 6, 86, 87, 458, 462
tobacco 6, 96, 97, 458, 531, 544, 545
Standard pure bone superphosphate of lime 6, 62, 63, 458,
516, 517
Success fertilizer 6, 66, ^"j, 458, 522, 523
Animal bone and potash 458, 524, 525
Bone meal 6, 42, 43
Celebrated ground bone acidulated 458, 494, 495
Little peach 869
Maize ensilage 721
meal , 172, 721
Malt sprouts 176, 202, 203, 754, 755
Manchester, E., & Sons : —
Manchester's formula 6, 56, 57, 459, 500, 510, 511
Manure, analysis of shredded 116
Mapes F. & P. G. Co. :—
Average soil complete manure 6, 58, 59, 459, 514, 515
Cereal brand 6, 98, 99, 459, 554, 555
Complete manure "A" brand 6, 70, 71, 459, 522, 523
Corn manure 6, 92, 93, 459, 552, 553
Economical potato manure 6, 84, 85, 459, 544, 545
Fruit and vine 6, 94, 95, 459, 552, '553
Potato manure 6, 86, 87, 459, 542, 543
Seeding down manure 6, 80, 81, 459, 536, 537
Tobacco ash constituents 6, 104, 105, 459, 558, 559
manure, wrapper brand 6, 104, 105, 459, 558, 559
starter, improved 6, 84, 85, 459, 558, 559
Top dresser, improved, full strength 7, 56, 57, 459, 510, 511
half " 7, 66, 67, 459, 516, S17
Vegetable manure, or complete manure for light soils 7, 60, 61, 459,
512, 513
Dissolved bone 6, 56, 57, 459, 512, 513
Maple, black spot of 852
Maple borer 336
syrup 150, 712, 713
INDEX. 923
Page.
Marine mud, analysis of 119
Meadowsweet, anthracnose of 352
Meat extracts 606
analyses of fluid 642
chlorine in fluid 643
claims of manufacturers of fluid 647
discussion of claims of the manufacturers of 634
fluid 640
fluid, statement of brands found pure, misbranded
or adulterated 651
how to value ■ 609
methods of analysis of 611
net weight and selling price of 615
nitrogenous constituents of fluid 644
paste 614
phosphoric acid in 624
physiological effect of 607
potash in 624
preservatives in 633
in fluid 647
review of literature of 664
sodium chlorid in 622
standards of composition of 609
statement of brands found pure, misbranded or
adulterated 639
table of chemical analyses of ^ . . . 618-621
the meat bases in , 629
fluid 646
the nitrogenous constituents of 625
juices 652
powders and meat capsules 659
preparations 606
fluid proprietary 655
scrap 182, 208, 209, 732
Melampsorella Caryophyllaceum 394^
elatina 394
Melampsoridium Betulae 386
Melampsoropsis Cassandrae 373, 386
Pyrolae 373, 388, 393
Melittia satyriniformis 805, 806
Mendelism in corn breeding, practical use of 406
Mendel's law of inheritance 408
Microgaster .* 786
Microrophala vittata 844
Microsphaera Aim 859, 866, 868
Milk 162, 712, 713
analysis of dried 734
924 INDEX.
Page.
Mites 770
Molasses 162, 713
analysis of 183
grains 179, 206, 207, 731
Monophadnoides rubi 846
Mosquito breeding conditions 318
Mosquito work, Beaver Swamp 802
East Haven rifle range 800
Stamford 804
Muck, analyses of swamp 569
Muskmelon chlorosis 865
Mustard 156, 157, 714
Myriapod, an injurious 2>Z7
National Fertilizer Co. : —
Chittenden's Ammoniated bone phosphate 7, 10, 459, 526, 527
Complete fertilizer 7, 62, 63, 459, 518, 519
tobacco 7, 84, 85, 100, loi
Connecticut Valley tobacco grower ...7, 104, 105, 459,
558, 559
starter 7, 80, 81, 459,
536, 537
Fish and potash 7, 60, 61, 459, 518, 519
Formula "A" 7, 56, 57, 459, 512, 513
"B" 7, 58, 59, 459> 462
H. G. special tobacco fertilizer 7, yy, 80, 81, 459,
536, 537
Market garden fertilizer 7, 64, 65, 459, 518, 519
Potato phosphate 7, 86, 87, 459, 540, 541
special 459, 546, 547
Tobacco special with carbonate of potash ..7, 104, 105,
459, 558, 559
XXX fish and potash 7, 56, 57, 459, 514, 515
Soluble bone and potash 7, 70, 71, 459, 526, 527
Dry ground fish 7, 46, 47, 459, 498, 499
Nitrate of soda 13, 14, 459, 465
Dried blood 466
Castor pomace 481, 482
Necium Farlowii 389
Nectarophora cuciirbitae 805, 814
New England Fertilizer Co. : —
New England Com and grain fertilizer ...7, 100, loi, 459, 554, 555
H. G. potato fertilizer 7, 88, 89, 459, 546, 547
Perfect tobacco grower 7, 104, 105, 459, 540, 541
Potato fertilizer 7, 96, 97, 459, 554, 555
Superphosphate 7, 64, 65, 459, 518, 519
Ground bone 7, 42, 43, 459, 494, 495
Muriate of potash 488, 489
Tankage 496, 497
INDEX. 925
Page.
New Jersey tea, powdery mildew of 866
Niantic Menhaden Oil & Guano Co. : —
Bone, fish and potash 459, 514, 515
Nitrate of soda, analyses of 13, 464
Nodonota puncticollis 845
North Western Fertilizing Co. : —
North Western Bone, fish and potash 459, 518, 519
Empire special manure 7, 58, 59, 459, 510, 511
Market garden phosphate ..7, 60, 61, 459, 518, 519
Superphosphate 7, 60, 61, 459, 514, 515
10% manure 7, 56, 57, 459, 510, 511
10% potato fertilizer 7, 92, 93, 459, 550, 551
Universal fertilizer 459, 518, 519
Nothrus ovivoriis 786
Nursery firms receiving certificates in 1907 269
1908 771
inspection 268, 765, 770
Oak, anthracnose of white , 352
limb-gall of 866
Ogdoconta cinereola 828
Ohio Farmers Potato and Tobacco Special 77, 92, 93
Okra, powdery mildew of 867
Olds & Whipple:—
O. & W.'s Complete tobacco fertilizer ....7, 104, 105, 460, 558, 559
Corn and potato fertilizer 7, 82, 83, 100, loi, 460, 536,
537
Fish and potash 460, 516, 517
Grass fertilizer 7, 82, 83, 460, 540, 541
H. G. potato fertilizer 7, 82, 83, 460, 536, 537
Special phosphate .7, 62, 63, 460, 510, 511
Dry ground fish 460, 498, 499
Grey pomace 7, 30, 460, 481, 482
Vegetable potash 7, 108, 460, 487
Precipitated bone 34, 485
Carbonate of potash 486, 487
Olive oil 151, 714
analyses of 151
O tiorynchus sulcatus 846
Pagoda tree, powdery mildew of 868
Paleacrita vernata 782, 794
Pamphilius persicum 285, 767
Paris green 767, 824
analyses of 328
chemical composition of 321, 326
Parmenter & Polsey Fertilizer Co. : —
"A. A." brand 7, 58, 59, 460, 462
Plymouth Rock brand 7, 64, 65, 460, 516, 517
926 INDEX.
Page.
Parmenter & Polsey Fertilizer Co., cont'd-^
Special potato fertilizer 7, 88, 89, 460, 462
Star Brand 7, 10
P. & P. Potato fertilizer 7, 98, 99, 460, 552, 553
Ground bone 7, 42, 43, 460, 494, 495
Muriate of potash 460, 488, 489
Nitrate of soda I3> i4
Parsley, drop of 868
Peach, bacterial spot of 856
collar girdle 856
gummosis 869
injury from droughts 874
leaf-fall of 342
httle 869
sawfiy 285, 767
description 295
yellows 872
preventive measures 877
theories concerning 875
winter injury 873
Peanut refuse 183
Pear injured by weevil 843
Peas and beans, ground I75
Peat, analyses of ' 569
Pegomyia brassicae 832
Pepper, black I54, i55, i57, 7i3
white 156, 157
Percentage difference, explanation of 5I) 502
Peridermia, literature of 394
relationships of 37i
Peridermium acicolum 374. 375
balsameum 392, 393, 394
columnare 393
conorum Piceae 388
■ consimile 386
elatinum 394
Laricis 386
oblongisporhim : . . 375. 394
Peckii 350, 383, 384, 391, 394
Pini 375
pyriforme • • 353, 380
Rostriepi 374
Strobi 394
Per 0110 plasmopora cubensis 862
Phellomyces sclerotiophoriis 358
Phragmidium speciosum 359
siibcorticium 359
INDEX. 927
Page.
Phyllosticta maxima 871
Pteridts 350
Phytophthora, artificial cultures of with reference to oospores . . . 891
Phytophthora infestans 891, 893, 894, 895, 900
cross-cultures 899
cultural methods 897
hybrid (?) cultures 900
life history 895
media 898
Nicotianae 891
Phaseoli 891, 893, 894, 900, 901
attempts to lose oospores 906
cultural methods 903
life history 901
media 904
Thalictri 893
infection experiments 895
life history 894
Pine blight 353, 852
leaf scale on hemlock 334
rust of white 353
Pines for forest planting 212
Plagionotus speciosus 33^
Plant lice 77^
Plasmopara viticola 854
Plathypena scabra 769, 82S
Platygaster 786
Platynus punctiformis 822
Podisus maculiventris (spinosiis) 769, 822
Pontia rapae 7^8
Poplar borer 335
Poppy? bacterial spot of 870
Potash, analyses of carbonate of 35, 486
double sulphate of 35, 36, 488-490
high grade sulphate of 35, 36, 487, 488
muriate of 36-38, 488-490
Potato beetle 768
breeding, some assential points in 429
Potato, characters of pollen 435
correlations between characters 443
description of flowers 435
growth of the seed berry 440
internal brown spot of 355
notes on tip-burn of 34^
scurf of 357
summary of procedure in hybridizing 442
variety variation in flowering 430
928 INDEX.
Page.
Potter wasp 786
Poultry feeds, proprietary 181, 208, 209, 731, 760, 761
Powdery mildew of azalea 859
currant 348
false indigo 349
grape 855
New Jersey tea 866
okra 867
pagoda tree 868
sunflower 871
Praying mantis 822
Precipitated bone, analyses of 34, 485
Preservatives in meat extracts 633
fluid meat extract 647
Preserves, fruit 581
Priophorus acericaulis 298
Proteoses, method of determining 613
Pseudomonas Pruni 856
Pseudopesiza Ribis 347
Pteronus ribesii 768
Pterostichus lucuhlandus 844
Puccinia Chrysanthemi 861
Helianthi 871
Menthae 859
Pucciniastrum Agrimoniae 391
arcticum americanum 391, 393, 394
balsameum 394
minimum '. 392, 854
Myrtilli 394
pustulatum • 392, 393
Pyrolae 393
Vacciniorum 394
Purin bases, method of determining 614
Pyramidal caterpillar 848
Pyrophila pyramidoides 848
Pythium sp 359
Quedius molochinus 822
Quince, rust of 851
Rabbit bot-fly 338
Radish, spindling of 871
Ramularia Taraxici 862
Raspberry syrup 585
Red dog flour 720, 748, 749
Reduvius novenarius 822
Report of agronornist 397
board of control ix
botanist 339, 849
INDEX. 929
Page.
Report of entomologist 266, 763
forester 211
treasurer xix, xxi
on feeding stuffs 165, ivj
fertilizers i, 453
food products 121, 573
Rhizoctonia sp 359
Rhododendron, leaf spot of 871
Rhytisma acerinum 852
Rice feed 734
products I75> 202, 203
Roestelia aurantiaca 35i) 831
pirata 851, 853
Rogers & Hubbard Co. : —
Hubbard's Complete phosphate 7. 68, 69, 460, 520, 521
Fertilizer for oats and top dressing 7, 78, 79, 460, 536,
537
Grass and grain fertilizer 8, 80, 81, 460, 540, 541
Market garden fertilizer 8, 58, 59
Potato phosphate 8, 86, 87, 460, 538, 539
Soluble corn and general crops manure 8, 62, 63, 460,
516, 517
potato manure 8, 80, 81, 460, 534, 535
tobacco manure 8, 80, 81, 460, 534, 535
Pure raw knuckle bone flour 8, 42, 43, 460, 494, 495
Strictly pure fine bone 8, 42, 43, 460, 494, 495
Rogers Mfg. Co. : —
All round fertilizer 8, 48, 64, 65, 68, 69, 460, 522, 523
Corn and onion 8, 78, 79, 460, 531, 532, 536, 537
Fish and potash 8, 66, 67, 460, 500, 518, 519
Grass and grain 8, 78, 79, 460, 534, 535
H. G. soluble tobacco 8, 78, 79, 100, loi, 460, 534, 535
Oats and top dressing 8, 78, 79, 100, loi, 460, 529, 534, 535
Potato and vegetable 8, 88, 89, 460, 538, 539
Tobacco and potato 8, 82, 83, 460, 534, 535
grower 8, 80, 81, 460, 530, 534, 535
starter 8, 84, 85, 460, 544, 545
Fine ground bone 8, 42, 43, 460, 494, 495
Knuckle bone flour 8, 42, 43, 460, 494, 495
Black potash 487
Tankage 496, 497
Root rot of tobacco 363
method of sterilizing seed beds 364
Rose, rust of 359
Russia Cement Co see Essex Fertiliser Co.
Rust of apple 853
azalea 854
930 INDEX.
Page.
Rust of bee balm 859
bellflower 343
blackberry 344
chrysanthemum 861
hemlock 350
June berry 351
rose 359
sunflower 871
white pine 353
Rusts, Heteroecious of Connecticut having a peridermium 369
Rye products 174, 202, 203, 726, 752-755
Salt, Cerebos 595
Ivory Compound 598
Shaker 598
table 586
Salt-waste, analysis of 118
Saltpeter waste, analysis of 118
Sanderson Fertilizer & Chemical Co. : —
Atlantic Coast bone, fish and potash 8, 66, 67, 460, 522, 523
Sanderson's Corn superphosphate 8, 94, 95, 460, 546, 547
Formula A 8, 60, 61, 460, 512, 513
B for tobacco 8, 82, 83, 84, 85, 100, loi, 460,
538, 539, 554, 555
Potato manure 8, 96, 97, 460, 544, 545
Special with 10% potash 8, 50, 68, 69, 460, 512, 513
Top dressing for grass and grains 8, 84, 85, 460, 546,
547
Fine ground bone 8, 42, 43, 460, 494, 495
fish 8, 46, 47, 460, 498, 499
Blood, bone and meat 461, 496, 497
Acid phosphate 461, 483, 484
Kainit 461, 488, 489
Muriate of potash 8, 36, 37, 461, 488, 489
Nitrate of soda 8, 13, 14, 461, 465
Sulphate of potash 8, 36, 37, 461, 488, 489
Special mixture No. i 526, 527, 528, 529
No. 2 528, 529
Fenn's formula No. i 526, 527
No. 2 526, 527
Special top dressing 528, 529
San Jose scale 768
Saperda calcarata 336
Candida 333
Sawfl}'-, peach 285, 767
description 295
raspberry 846
'"Scalecide" 282
INDEX, 931
Page.
Sclerotinia Libertiana 860, 863, 868
Screenings, botanical analysis of 182
Scurf of potato 357
Selandria obsoletum 286
Separator skim milk 162
Septoria Kalmicola 351
Shay, C. M., Fertilizer Co. : —
Shay's Corn fertilizer 8, 78, 79, 461, 532, 546, 547
Grass and lawn 8, 78, 79, 461, 534, 535
Potato 8, 78, 79, 461, 509, S34> 535
Pure ground bone 8, 42, 43, 461, 494, 495
Muriate of potash 488, 489
Tankage 496, 497
Sheep manure, analyses of 114, 116
Shoemaker, M. L., & Co. : —
"Swift-Sure" Guano for truck, corn and onions 9, 82, 83, 461, 536,
537
Superphosphate for general use 9, 58, 59, 461, 510, 511
potatoes ..9, 82, 83, 461, 536, 537
Bone meal 9, 42, 43, 461, 494, 495
Snow-white linden moth 842
Soldier bug, spined 769, 822
Soluble oils, home-made 837
various kinds 840
"Soluble oils," spraying tests with 282
Southern com root-worm 805, 8c^
Special manures 74, 528
cost and valuation of yy, 532
guaranties of 76, 532
tables of analyses of 78-101, 534-555
Sphaerotheca mors-uvae 348
Spices 152
Spiny elm caterpillar 267, 768
Spondylocladium abietinum 359
atrovirens 357
Sporotrichum globuliferum (entomophilum) 821
Spray injury of apple 342
Spraying for the peach sawfly 294
with "soluble oils" 282
Squash aphis 805, 814
borer 805, 806
bug 805, 81 1
lady-beetle , 805, 810
Siagmo mantis Carolina 822
Star feed 726, 752, 753
Starch, arrowroot 574
corn 574
932 INDEX.
Fage.
Starch, potato 574
Station, officers and staff of iii
Stem-rot of herbaceous plants 351
Sulphate of ammonia, analysis of 15
Sulphuretted hydrogen, used for fumigation 275
Sumatra disease of tobacco 360
Sunflower, powdery mildew of 871
rust of 871
Superphosphates, analyses of nitrogenous S6-7S, 510-529
cost and valuation of nitrogenous 50, 501
guaranties of nitrogenous 49, 501
nitrogenous 46, 500
Sweet pea, dampening ofi 359
Swift's Lowell Fertilizer Co. : —
Swift's Lowell Animal brand 9, 66, 67, 68, 69, 461, 509, 514, 515,
516, 517
Bone fertilizer 9, 98, 99, 461, 524, 525
Dissolved bone and potash 9, 70, 71, 461, 520, 521
Empress brand 9, 98, 99, 461, 524, 525
Market garden manure 9, 60, 61, 461, 501, 512, 513
Perfect tobacco grower ...9, 104, 105, 461, 542, 543
Potato manure 9, 76, 96, 97, 461, 552, 553
phosphate 9, 76, 80, 81, 92, 93, 461, 542, 543
Special grass mixture 9, 82, 83, 461, 540, 541
vegetable manure 9, 77, go, 91
Ground bone 9, 42, 43, 461, 494, 495
Tobacco manure 461, 538, 539
Acid phosphate 9, 32, 33, 461, 483, 484
Muriate of potash 9, 36, 37, 461, 488, 489
Nitrate of soda 9, 13, 14, 461, 465
Dried blood .' 15, 466
Tankage 44> 45, 496, 497
Sycamore, frost inj ury 360
Syntonin, method of determination of 612
Table of contents v
Tables showing results of fumigating with gases ...274, 276, 278, 279, 281
Tankage, analyses of slaughterhouse 41, 45, 493, 497
valuation of 40, 493
"Target Brand Scale Destroyer" 282
Tarred paper disks 835, 836
Tartar pomace, analysis of 118
Tetranychus bicolor 770
Tetrastichus xanthonielaenae 821
Thielavia basicola 363
Three- Lined leaf beetle 844
Thyridopteryx ephemeraeformis 337
Tincture of iodine 707
INDEX. 933
Page.
Tischeria malifoliella 267, 768
Tobacco beds, methods of sterilizing 364
in 1908, root rot of 851
manures containing potash as carbonate 102, 556
guaranties 557
tables of analyses of 104, 105, 558, 559
Tobacco, root rot of 342, 363
Tobacco stalks, analysis of 117
analyses of ashes of 117
Tobacco, Sumatra disease of 360
Tomato, chlorosis of 362, 857
Treasurer, report of xix, xxi
Trirhabda canadensis 844
Trumpet creeper, leaf blight 362
Uncimda necator 855
Uredo aecidioides 385
Muelleri 383, 384, 385
Valuation of fertilizers 39, 491
Vanilla extract 158, 714
Vegetable potash, analyses of 108, 487
Vinegar 162, 714
Visco Cream 713
Water sheds, planting of 244
Weather conditions in 1907, notes on 339
1908, notes on 849
Weevil, New York 845
strawberry 846
Wheat and corn-cob feeds 178, 206, 207, 727, 756, 757
bran 170, 192-19S, 7^9, 742-745
feed 171, 196-199, 719, 746-749
middlings 171, 194-197, 719, 744-747
products 170, 718
Wheeler Bros. :—
Wheeler's Special potato 461, 536, 537
Ammoniated bone and potash 516, 517
Corn special 534, 535
White fly, greenhouse 806, 815
Wilcox Fertilizer Co. : —
Wilcox's Complete bone superphosphate 9, 58, 59, 461, 516, 517
Fish and potash 9, 64, 65, 461, 512, 513
Grass fertilizer 9, 82, 83, 461, 536, 537
H. G. fish and potash 9, 56, 57, 461, 510, 511
tobacco special 9, 74, 78, 79, 461, 536, 537
Potato fertilizer 9, 86, 87, 461, 548, 549
onion and vegetable manure 9, 80, 81, 461, 536,
537
Special superphosphate 9, 62, 63, 461, 520, 52:
934 INDEX.
Page.
Wilcox Fertilizer Co., cont'd —
Wilcox's Dry ground fish 9, 44, 47, 461, 498, 499
Pure ground bone 9, 42, 43, 461, 494, 495
Acid phosphate 9, 31, 32, 461, 483, 484
Muriate of potash 9, 36, 37, 38, 461, 4S8, 489
Nitrate of soda 9, 13, 14, 461, 465
H. G. sulphate of potash 9, 36, 37, 488, 489
Special mixture No. i 526, 527
No. 2 526, 527
Willow curculio 335
Witch hazel, analysis of 712
Wood ashes m, 562
tables of analyses of 112, 113, 564, 565
Woodruff, S. D., & Sons :—
Woodruff's Home mixture 9, 46, 48, 56, 57, 461, 510, 511
Muriate of potash 36, 37. 488, 489
Nitrate of soda 13, I4, 46S
Acid phosphate 483. 4^4
Yield tables of even aged forests 262
Zeuzera pyrina 847
State of Connecticut
PUBLIC DOOUMEl^T IsTo. 24
Thirty-first and Thirty-second Annual Reports
OF
The Connecticut Agricultural
Experiment Station
Being the biennial report for the two years ended October ZU
1908
PRINTED BY ORDET{ OF THE LEGISLATURE
HARTFORD
Published by the State
1908
publication
approved by
The Board of Control.
THE TUTTLE, MOREHOUSE & TAYLOR COMPANY
CONNECTICDT AaRICUlTDRAL EIPERIMEKT STATION.
BOARD OF CONTROL.
His Excellency, Rollin S. Woodruff, Ex officio. President.
Prof. H. W. Conn, Vice President Middletown.
Prof. W. H. Brewer, Secretary New Haven.
B. W. Collins Meriden.
Charles M. Jarvis Berlin.
Frank H. Stadtmueller Elmwood.
J. H. Webb Hamden.
E. H. Jenkins, Director and Treasurer New Haven.
STATION STAFF.
Chemists.
Analytical Laboratory.
John P. Street, M.S., Chemist in Charge.
E. Monroe Bailey, M.S. C. A. Brautlecht, Ph.B.
C. B. Morrison, B.S. Clarence W. Rodman, B.S.
Laboratory for the Study of Proteids.
T. B. Osborne, Ph.D., Chemist in Charge.
Botanist.
G. P. Clinton, S.D.
W. E. Britton, Ph.D.
Assistant in Entomology.
B. H. Walden, B.Agr.
Forester.
Austin F. Hawes, M.F.
Agronomist.
Edward M. East, Ph.D.
Seed Testing.
Mary H. Jagger.
Stenographers and Clerks.
Miss V. E. Cole.
Miss L. M. Brautlecht.
Miss E. B. Whittlesey.
Miss C. A. Botsford.
In charge of Buildings and Grounds.
William Veitch.
Laboratory Helper.
Hugo Lange.
Sampling Agent.
V. L. Churchill, New Haven.
TABLE OF CONTENTS.
PAGE.
Officers and Staff iii
Contents v
Report of Board of Control ix
Report of Treasurer xix
Corrections and Additions xxiii
Report on Commercial Fertilizers i, 453
Duties of Manufacturers and Dealers i, 453
Observance of the Fertilizer Law 2, 454
Sampling and Collection of Fertilizers 10, 462
Raw Materials chiefly valuable for Nitrogen 13-31, 464-482
Raw Materials chiefly valuable for Phosphoric Acid ..31-34, 483-486
Raw Materials of High Grade containing Potash ...35-38, 486-491
Raw Materials containing Nitrogen and Phosphoric
Acid 39-46, 491-499
Nitrogenous Superphosphates and Guanos 46-74, 500-528
Special Manures 74-106, 528-559
Home Mixtures 106-108, 559-560
Ashes, Cotton Hull and Wood 108-114, 560-567
Lime and Lime-Kiln Ashes 114-115, 567-568
Various Manurial Wastes 1 14-120, 568-570
Report on Food Products {See also below, p. 57s et seq.) 121
Buckwheat Flour 127
Catsup and Chili Sauce 129
Chocolate and Cocoa 134
Coffee 137
Cream of Tartar 138
Diabetic Foods 138
Honey 139
Hygienic Coffee 141
Lard 143
Lemon Extract 144
Maple Syrup 150
Olive Oil 151
Spices 152
Vanilla Extract 158
Miscellaneous 162
Samples sent by Dairy Commissioner 162, 713
Summary 163, 715
Report on Feeding Stuffs -. 165, 717
Sampling and Explanations 166
Uses of Analyses 168
vi CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
PAGE.
Report on Feeding Stuffs, cont'd —
Oil Seed Products 169-170, 717-718
Wheat Products 170-172, 718-720
Corn Products 172-174, 721-726
Rye Products 174, 726
Buckwheat, Rice and Miscellaneous Products 175, 726
Barley Products 176-177, 726-727
Various Mixed Feeds 178-179, 727-728
Proprietary Horse Feeds 180, 729
Proprietary Dairy and Stock Feeds 180, 729
Proprietary Poultry Feeds 181, 731
Miscellaneous Feeds 183, 72,2
Digestibility of Feeding Stuffs 183, 735
Regarding the Purchase of Feeds 185, 735
Weight of One Quart of Various Feeds 189, 762
Commercial Feeds containing Weed Seeds 72>^
Analyses of Feeds 190-209, 740-761
Report of Forester 211
Forest Plantations 211
Description of Forest Planting Experiments 213
Summary of Results 230
Recent Plantations in Connecticut 242
Plantations in State Forests 242
Planting Water Sheds 244
Educational Institutions 246
Private Plantations 248
Older Forest Plantations in Connecticut 251
Yield Tables of Even Aged Forests in Europe 262
Report of Entomologist {See also below, p. 763) 266
Nursery Inspection 268, 770
Tests of Gases for Fumigating Stock 270, 796
Spraying Tests with Soluble Oils 282
The Peach Sawfly 285
Progress of Work in Controlling the Gypsy Moth 300, 772
The Brown Tail Moth 313
Mosquito Studies 318, 800
The Chemical Composition of Lead Arsenate and Paris Green 321
Notes on Various Insects 332-338, 842-848
Report of Botanist (See also below, p. 850) 339, 849
Notes on Fungous Diseases 339, 849
Root Rot of Tobacco 363
Heteroecious Rusts of Connecticut 369
Report of Agronomist 397
The Prospect of Better Seed Com in Connecticut 397
Practical Use of Mendelism in Com Breeding 406
Inbreeding in Corn 419
Some Essential Points in Potato Breeding 429
Extension Work in Agronomy 448
TABLE OF CONTENTS. vii
PAGE.
Report on Food Products {See also above, p. 121) 573
Starches 574
Ginger 574
Jams, Jellies and Preserves 581
Salt 586
Infant and Invalid Foods 599
Meat Extracts 606
Fluid Meat Extracts 640
Other Meat Preparations 655
Bibliography of Meat Extracts 664
Report on Drugs :
Beef, Wine and Iron 673
Headache Preparations 686
Ammonia Water 704
Tincture of Iodine 707
Borax 710
Miscellaneous Foods and Drugs 711
Foods and Drugs Examined for the' Dairy Commissioner 713
Summary ^ 715
Report of Entomologist {See also above, p. 266) 763
Financial Reports y62,
Entomological Features of 1908 768
Canker Worms yyy
Insects attacking Cucurbits 805
Elm Leaf Beetle 815
Green Clover Worm 828
Treatment of Cabbage Plants to Prevent Injury by Cabbage
Maggot 832
Soluble Oils, home-made 837
Report of Botanist {See also above, p. 339) 850
Peach Yellows and So-called Yellows 872
Chestnut Bark Disease 879
Artificial Cultures of Phytophthora 891
Report of the Board of Control
OF THE
CONNECTICUT AGRICULTURAL EXPERIMENT
STATION.
To His Excellency, Rollin S. Woodruff, Governor of Connecticut:
The Board of Control of the Connecticut Agricultural Experi-
ment Station, as required by law, herewith submits its report for
the two years ending November ist, 1908.
Professor Wilbur Olin Atwater, of Wesleyan University, died
in Middletown, Conn., September 22d, 1907.
The members of the Board of Control of the Connecticut Agricultural
Experiment Station, with this notice of his death, desire also to record
their appreciation of the great work which Professor Atwater did for the
cause of Agricultural Research, both in Connecticut and in the country at
large. Active and helpful in encouraging an interest in the subject and in
urging the estabhshment of an Agricultural Experiment Station in Con-
necticut, he became Director in the first Station established on this conti-
nent, in 1875, and his influence contributed very largely to the successful
establishment of agricultural experiment stations in other states.
He was also for fourteen years Director of the Storrs Station.
After the United States Department of Agriculture had been created
and when the office of Experiment Stations was organized within it,
Professor Atwater was appointed its first director, which office he held for
three years and did much in shaping its policy and work.
For nearly twenty-seven years and until his last illness, he was a valued
member of this Board, contributing to the management of its affairs the
faithfulness, experience and good sense which had made him so success-
ful in his other work.
Edwin Hoyt, a member of the Board of Control of this Station
continuously since its incorporation in 1877, died at his home in
New Canaan, on April 17th, 1908.
Born in 1832, educated in the schools of his native town, he spent a
year in further study at the Potter School, at Niagara Falls, and a winter
at the Sheffield Scientific School of Yale University, and in 1856 entered
the nursery business estabhshed by his father, and continued in it until
his death.
X CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
The nursery became the largest in New England, and Mr. Hoyt became
known throughout the country as an expert nurseryman and orchardist.
He was a member and an officer in the State Grange, the State Pomo-
logical Society, and other agricultural organizations, both state and
national, and his papers presented at meetings of such bodies were always
concise, convincing, and valued as the opinion of a disinterested and
honest expert.
In his native town he was a prominent worker in the cause of temper-
ance, a member of the Congregational Church, and an office holder in it
for more than forty years, and interested in every movement for the
advancement of his town and the welfare of its citizens.
He had represented his town in the General Assembly, and at the time
of his death was President of the First National Bank of New Canaan.
In all the relations of life he showed himself scrupulously honest,
generous and broad-minded, a lover of righteousness and a hater of
iniquity.
The members of this Board desire to place on record their appreciation
of the long, faithful and valuable service which Mr. Hoyt rendered to
the Agricultural Station. His interest in it and his services for it began
while it was still only talked of as a possibility, and continued as long as
he lived.
The General Assembly, by joint resohition approved May ist,
1907, accepted the provisions of the so-called Adams Act of the
Congress of the United States and directed that one-half of the
fund appropriated by this act should be given to this Station and
one-half to the Storrs Station.
An act of the last General Assembly concerning Printing, Chap-
ter 133, limits the edition of the Station report to 12,000 copies,
the number of pages to 400, and provides that it shall be issued
biennially. Authority is, however, given to the State Board of
Control to limit the number of copies printed and to permit the
printing of a larger number of pages of such reports as were made
biennial by this act. The Board has authorized the printing of
ten thousand copies of the report, not to exceed 900 pages, at the
state expense, and allows it to be issued in parts as the material is
prepared, so as to place the results of the work before the public
as soon as they are ready.
A third act of the Assembly affecting this Station is the P'ood
and Drug Law, Chapter 255, which is quite like the National
Law, and charges this Station with the examination of drugs as
well as food products, but makes no appropriation for the drug
work. The Station, however, has been able to do something in
the examination of druefs.
REPORT OF THE BOARD OF CONTROL. XI
Mr, F. H. Stadtmueller, of Elmwood, was appointed a member
of this Board to fill the unexpired term of Mr. Hoyt.
On May ist, 1907, Dr. A. L. Winton, chemist in charge of the
analytical laboratory, after twenty-three years of most valuable
service to this Station, resigned to accept the position of chief
of the United States Food and Drug Laboratory in Chicago.
On September ist, 1907,' Mr. E. J. Shanley resigned his position
as chemist, to take a similar position in the Chicago Food and
Drug Laboratory.
On October ist, 1907, Dr. Kate G. Barber, the Station micro-
scopist, resigned to take a similar position in the Bureau of Chem-
istry of the United States Department of Agriculture at
Washington.
Mr. John Phillips Street, a graduate of Rutgers College, and
for eighteen years connected with the New Jersey Station, was
appointed to succeed Dr. Winton, on May ist, 1907.
Mr. C. B. Morrison, a graduate of the Rhode Island Agricul-
tural College, and employed at the time by the Sewage Purification
Department of the City of Providence, R. L, was engaged as
chemist in September, 1907, and in November, 1907, Mr. Harry
R. Stevens, a graduate of the University of Vermont, was also
added to the staff as chemist, but was obliged to resign in May,
1908, on account of ill health.
Mr. K. G. Mackenzie, a graduate of Yale University, also served
the Station as chemist for five months in 1908.
Mr. C. A. Brautlecht, a graduate of the Sheffield School of
Yale University, was appointed to the Station staff as chemist in
April, 1908.
In January, 1908, Miss Mary H. Jagger was employed to
attend to the work of seed testing.
In October of the same year Mr. Clarence Rodman, a graduate
of the University of Pennsylvania, and employed at the time as
a chemist in the Philadelphia Water Works, was engaged as
chemist.
During the summer months of 1907 and 1908, Mr. Paul Graff
was employed to put in order and arrange the additions to the
herbarium which are noticed later in this report.
Messrs. F. F. Moon and Allen Hodgson, during the same
time, assisted Mr. Hawes in the forest survey of the state.
xii CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
Six hundred and fifty-one analyses of fertilizers were made in
1907, including all of the two hundred and seventy-nine brands
registered for sale in the state, and the results published with
appropriate discussion as Part I of the biennial report.
In 1908 six hundred and thirty-one fertilizer analyses were
made, and the results are already in type.
In 1907 fifteen hundred and ninety-four food products were
examined with reference to adulteration and all cases of adultera-
tion reported to the dairy commissioner, with whom rests the
enforcement of the law. A full report on all the samples was
issued as Part II of the report.
In 1908 ten hundred and seventy-four analyses of foods, and
four hundred and four of drugs were made and reported to the
commissioner as before. The results are nearly ready for
printing.
Two hundred and thirty-seven samples of feeding stuffs, includ-
ing nearly if not quite all the brands sold in Connecticut, were
analyzed in 1907, and the results published and discussed in Part
III of the report. In 1908 about the same number have been col-
lected and are now being examined.
Examinations and analyses have been made of all the brands
of arsenical insecticides which could be found in the state, twenty-
three in number, and the results printed in Bulletin 157.
As usual, a good deal of miscellaneous analytical work has
been done, and also work in testing and improving analytical
methods.
One hundred and fifty-four pieces of measuring apparatus for
the Babcock test have been tested for creameries and individuals.
Nine pieces were condemned as inaccurate.
The work done during 1907 and 1908 in the laboratory for
protein research, supported in part by the Carnegie Institution
and in part by the Adams fund, may be summarized as follows :
A full report on the Chemistry of Protein of the Wheat
Kernel has been made and published by the Carnegie Institution
as Publication 84.
A new substance, a dipeptide of proline and phenylalanine, has
been isolated from one of the wheat proteins. This substance
is important, not only in connection with the structure of wheat
protein, but in connection with the chemistry of proteins in
general.
REPORT OF THE BOARD OF CONTROL. Xlil
Quantitative determinations have been made of the proportions
of decomposition products yielded by a considerable number of
vegetable proteins, and the results have been published.
Similar determinations have been made in a number of animal
food substances to compare with the others, and to determine
whether or not wide differences in decomposition products
existed between animal food substances similar to those in
vegetable proteins.
The extended study of the determination of the different forms
of nitrogen in a large number of vegetable and animal proteins
has been finished.
Experiments with the nucleic acid of wheat have settled an
important point in the chemistry of this class of substances which
has been the subject of much controversy.
The results of the work of this laboratory have been given in
twenty-one papers published in scientific journals.
During 1907 and 1908 the entomological department has spent
much effort in subduing the gipsy moth at Stonington, the only
place in the state where it has been found. The infested area has
been isolated as well as could be by the destruction of shrubs and
bushes on all sides of it, and has been made considerably smaller,
and within the area all larvae, pupae and egg masses discoverable
by men working from November, 1906, to September, 1908, have
been destroyed. Fourteen thousand trees were banded and
inspected daily during the caterpillar season of each year, and
fifty-five hundred caterpillars, two hundred pupae, and one hun-
dred and forty-one newly laid egg masses were destroyed.
By act approved June 5th, 1907, the General Assembly of 1907
appropriated $1,000 for fighting the gipsy moth, and provided that
the State Board of Control might supply additional funds to the
amount of $10,000, if, in their judgment, it should be necessary.
Five thousand dollars have been spent from this appropriation,
one hundred dollars supplied by the State Board of Agriculture,
and $1,513.34 from the regular state appropriation for the
entomologist.
A new orchard pest, the peach saw-fly, which proved to be a
new species, was studied, and its life history determined and
described. It was very abundant in the peach orchards of one
sections of the state, and threatened great injury. Under the
direction of the entomologist spraying with arsenate of lead
controlled the pest perfectly.
xiv CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
Experiments on the effectiveness of the fumigation of nursery-
stock with five different gases have been concluded.
Tests of remedies against the cabbage maggot and squash borer
have been completed on the Station grounds at Mt. Carmel.
Examinations of localities where mosquitoes breed have been
made, particularly at Beaver Swamp, New Haven, infected with
the malaria-bearing mosquito, and by request of health officers,
at the state rifle range. East Haven, and in the region about
Stamford.
A paper on the Orthoptera of the state has been prepared for
the Natural History Survey by Mr. B. H. Walden, and a gen-
eral introduction to the insects of the state by Dr. Britton.
The insect collection now contains nearly 3,500 species, and
over 30,000 specimens.
Ninety-two nurseries and seventy orchards and gardens have
been inspected, and 338 samples of insects identified in answer
to inquiries.
Four papers on entomological subjects have been prepared for
scientific journals or reports.
The work of the agronomist, in large part supported by the
Adams fund for scientific research, may be summarized as
follows :
Dr. East has finished a preliminary study of the factors
involved in the improvement of the potato, the relation of physical
and chemical characters to quality, and the amount of fluctuation
of these characters, a work begun at the University of Illinois,
in 1 90 1, completed here, oft'ered as a thesis for the doctorate
degree, and pubHshed by the Illinois Station as Bulletin 127.
A study of the physiology of the production of seed and of
the difficulties attending hybridization in the potato, in which over
seven hundred varieties have been under observation, has been
finished and the results published.
In a study of inheritance of fluctuations within a bud propa-
gating line (potatoes), using the nitrogen fluctuation for the
observed character, the second generation has been grown.
The crosses between varieties of potatoes made in 1907 were
grown in 1908, in order to study the inheritance of different unit
characters.
In a study of the graft hybrids in potatoes it has been shown
that no transference of coloring matter can be made, and cer-
tain errors in published work on the subject have been explained.
REPORT OF THE BOARD OF CONTROL. XV
Some interesting results on bud variation have been obtained
which offered a new explanation for the phenomenon.
The experiment at Elmwood in increasing by selection the pro-
tein content of a variety of corn has been continued. At the
station at Granby several hundred crosses of corn have been made
to determine the inheritance of various characters, and the second
generation of several previous crosses have been grown, as well
as the third generation of certain inbred varieties.
The cooperative tests in corn breeding, started in I905» have,
in 1908, been left entirely to the cooperators.
In studying the laws of inheritance with tobacco, which is a
plant better suited to the purpose than any other of economic
value grown here, 125 varieties have been grown for classifica-
tion, for observation as to commercially desirable kinds, and,
chiefly, to obtain varieties with different unit characters to use in
heredity experiments.
In the greenhouse an experiment with tomatoes is in progress
to determine whether it is possible by abnormal treatment of the
developing seed to change in any way the usual characters of
the offspring. The question is one of great economic importance.
Field, laboratory, and pot experiments have been made to test
the availability of potassium in fine ground feldspar, so far
without decisive results.
On the Station farm land the study of soil needs and improve-
ment by rotations, cover crops, green manures and fertilizers has
been continued with observations on fall and spring seeding with
clover, together with experiments in spraying and other means
of combating insect and fungus attacks ; the latter under the
direction of the entomologist and botanist.
Four papers on the subject of Dr. East's work have been read at
meetings of specialists or published in scientific journals.
The botanist, Dr. Clinton, was absent on leave for two months
in 1908, to do some preliminary work on the inoculation of the
brown tail moth with the Empusa disease for the State of Massa-
chusetts. This was done at Harvard University under the direc-
tion of Prof. Thaxter, formerly botanist of this Station.
Besides study and observation on the fungous troubles of crops
in all parts of the state, collecting and arranging additions to
the herbarium, and conducting experiments on the Station experi-
Xvi CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
ment land and in the greenhouse, the study of the botanist dur-
ing the last two years has been chiefly on the following subjects :
1. The "Calico" disease of tobacco and chlorosis in other
plants.
2. The downy mildew of Connecticut. (For the State Nat-
ural History Survey of the state.)
3. A study of 100 varieties of muskmelons, especially regard-
ing their resistance to blight and adaptability to Connecticut
conditions.
4. The root rot of tobacco.
5. Certain Peridermia and their telial stage.
6. Potato blight.
On the Station's experimental forest the forester has con-
tinued experiments on the economic planting of white pine, and
on different methods of seeding and planting forest trees, on
fertilizing young trees by growing cow peas, on the progress of
the white pine disease, and the best treatment of the pine weevil.
The forest nursery contains about 950,000 seedling trees, mostly
one-year-olds, and 300,000 seedlings in addition have been sold
at cost to landowners.
Four acres of pine growth 30 years old have been bought in
Enfield for experiments in thinning.
The increased interest in forest planting is shown by the facts
that about 100,000 forest trees were planted in the state in 1906,
350,000 in 1907, and 600,000 in the present year.
A number of landowners in marketing their mature lumber
are doing the work by improvement thinnings planned by the
Station forester.
As state forester, Mr. Hawes has carried on improvement thin-
ning and planting work both at the Portland and Union forests.
A tract of 130 acres of waste land frequently burned over has
been bought for a state forest in Simsbury, and 20,000 trees
already planted.
The fire warden service has been greatly improved and a pam-
phlet of instructions to fire wardens, containing also a list of
wardens with telephone calls of those who have them, has been
distributed.
In 1908, alone, the wardens reported 156 fires, burning over
10,807 acres, of which 6,100 were sprout and timber land. 568
REPORT OF THE BOARD OF CONTROL. XVll
cords of cut wood were destroyed. i,347 men were employed
in fighting fire, and the total amount paid them by state, county,
and town was about $9.00 per fire.
In Simsbury, alone, a single patrol during the danger season
of April and May put out 35 fires before any considerable damage
was done.
A forest survey has been made of Litchfield and Fairfield
counties, and in cooperation with the Yale Forest School of New
Haven County, estimating the quantity and kind of the standing
timber. All wood lots of over ten acres are plotted on topo-
graphic sheets. The map is completed and the report prepared
on the wood supplies and wood industries of these counties.
Miss Jagger has made five hundred and thirty-five examina-
tions of seeds, a part on samples sent by seedsmen and buyers,
and a part bought by our sampling agent in different parts of
the state.
Twenty-eight thoroughbred Guernsey cows and twenty-nine
Jerseys have been tested for advanced registry by monthly deter-
minations of production of milk and of butter-fat. The tests of
twelve Guernseys and ten Jerseys have been finished, and eleven
were withdrawn before the year's test was finished.
At present seventeen Guernseys and eighteen Jerseys are being
tested.
Within the period covered by this report the Station has
acquired by purchase for its collections several hundred species
of European fungi, and the herbarium of J. N. Bishop, of Plain-
ville, containing between two and three thousand specimens.
Dr. W. A. Murrill, of the New York Botanical Garden, has
given the Station one hundred specimens of the common Poly-
porei.
Mr. James Shepard, of New Britain, has given the Station the
herbarium of his daughter, recently deceased. Miss Celia Antoi-
nette Shepard, containing one thousand or more species, chiefly
from Connecticut, but including many from other states and
foreign countries.
Prof. S. W. Johnson, formerly director of this Station, has
given, conditionally, to its library five hundred bound volumes
and many pamphlets from his valuable agricultural library.
These include sets of a number of valuable journals, almost
impossible to get now from book dealers, and works on scientific
Xviii CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
agriculture which represent its history and development from
the early years of the last century.
Members of the staff have made addresses at one hundred and
six institutes, grange meetings, and other agricultural gatherings.
The Station has cooperated with the United States Department
of Agriculture in tobacco breeding work and in a study of the
improvement of sweet corn by selection of seed.
In the two years the Station has published one report of four
hundred and twenty-three pages, with thirty-three plates, and one-
half its biennial report of four hundred and fifty-three pages,
with forty-seven plates. It has also issued six bulletins aggre-
gating one hundred and forty-one pages, with nine plates and
figures, and four bulletins of immediate information, aggregating
twenty-three pages and nine figures. The editions range from
eight thousand to ten thousand copies.
In the two years fourteen thousand three hundred and forty-
two letters and manuscript reports have been written and mailed
from the Station.
All of which is respectfully submitted.
(Signed) William H. Brewer, Secretary.
New Haven, Conn., November i, igo8.
REPORT OF THE TREASURER, 1907
E. H. Jenkins, in account with The Connecticut Agricultural Experi-
ment Station for the fiscal year ending September 30, 1907.
Receipts.
Balance on hand, October i, 1906 :
Analysis Fees $522.15
Insect Pest Appropriation 650.00
$1,172.15
State Appropriation, Agriculture $10,000.00
State Appropriation, Food 2,500.00
State Appropriation, Insect Pest 3,000.00
State Appropriation, Gypsy Moth 2,500.00
United States Appropriation, Hatch 7)5oo.oo
United States Appropriation, Adams 3,750-00
Analysis Fees 2,900.00
Miscellaneous Receipts 46-45
From the Lockwood Estate 10,800.00
42,996.45
Total $44,168.60
Disbursements.
E. H. Jenkins, Salary $2,800.00
W. H. Brewer; " 100.00
V. E. Cole, " 800.00
L. M. Brautlecht, " 600.00
A. L. Winton, " 1,458-33
J. P. Street, " 1,041.67
T. B. Osborne, " 2,200.00
E. M. Bailey, " 1,350.00
Kate Barber, " 1,066.66
E. J. Shanley, " 991.66
C. B. Morrison, " 18.75
W. E. Britton, " 1,700.00
G. P. Clinton, " 2,000.00
A. F. Hawes, " 1,291.66
E. M. East, " 1,700.00
J. B. Olcott, " 375-00
H. Lange, " 866.67
V. L. Churchill, " 760.00
William Veitch, " 633.33
T. E. Keitt, " 60.00
W. Drushel, " 150.00
R. W. Langley, " 358.90 ^
Labor 3,366.21
Publications 583.29
XX CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
Postage $ 160.45
Stationery 283.94
Telephone and Telegraph 211.65
Freight and Express 149.98
Gas and Kerosene 32921
Coal 1,302.05
Water 157-39
Chemicals and Laboratory Supplies i, 194-35
Agricultural and Horticultural Supplies 33i-i7
Miscellaneous Supplies 250.26
Botanical Supplies 72-20
Fertilizers 255.29
Feeding Stuffs 118.53
Library and Periodicals 594-68
Tools and Machinery 300-74
Furniture and Fixtures 137-40
Scientific Apparatus 82.33
Traveling by the Board 79-40
Traveling by the Staff 623.19
Traveling in connection with Adams' Fund Investi-
gations 178.76
Tobacco Experiment 75-30
Fertilizer Sampling 206.27
Food Sampling 34i-2i
Insurance 28.20
Insect Pest Appropriation to State Entomologist 3,650.00
Contingent 193-45
Forestry and Lockwood Expenses 2,256.85
Gypsy Moth Appropriation to State Entomologist . . . 2,500.00
New Buildings 88.12
Betterments ii5-27
Repairs 698.22
Rental of Land 120.00
Balance on hand, October i, 1907:
Analysis Fees $307-79
State Agricultural Appropriation 502.82
$43,357-99
810.61
Total $44,168.60
New Haven, Conn., November 5, 1907.
This Certifies that we have examined the accounts of E. H. Jenkins,
Treasurer of The Connecticut Agricultural Experiment Station, for the
year ending September 30, 1907, compared the same with the vouchers
therefor and found them correct.
William P. Bailey,
Edward S. Roberts,
Auditors of Public Accounts.
REPORT OF THE TREASURER, 1908
E. H. Jenkins, in account with The Connecticut Agricultural Experi-
ment Station for the fiscal year ending September 30, 1908.
Receipts.
Balance on hand, October i, 1907 :
Analysis Fees .' . . $307.79
State Agricultural Appropriation 502.82
$810.61
State Appropriation, Agriculture $10,000.00
State Appropriation, Food 2,500.00
State Appropriation, Insect Pest 3,000.00
State Appropriation, Gypsy Moth 2,500.00
United States Appropriation, Hatch 7,500.00
United States Appropriation, Adams 4,750.00
Analysis Fees 8,799.98
Sale of Tobacco 65.97
Sale of Farm Products 228.25
Miscellaneous Receipts 433-52
From the Lockwood Estate 9,177.40
48,955-12
Total $49,765.73
Disbursements.
E. H. Jenkins, Salary $2,800.00
W. H. Brewer, " 100.00
V. E. Cole, " 850.00
L. M. Brautlecht, " 650.00
J. P. Street, " 2,500.00
T. B. Osborne, " 2,200.00
E. M. Bailey, " 1,550.00
C. B. Morrison, " 925.00
H. R. Stevens, " 500.00
K. G. Mackenzie, " 363.50
C. A. Brautlecht, " 450.00
R. S. Graves, " 70.00
W. E. Britton, " 2,000.00
G. P. Clinton, " 1,833.32
A. F. Hawes, " » . . . 1,800.00
E. M. East, " 1,900.00
J. B. Olcott, " 200.00
H. Lange, " 925.00
V. L. Churchill, " 825.00
William Veitch, '" 675.00
H. W. Kiley (Labor) 728.00
Wm. Pokrob, " 728.00
C. D. Hubbell, " 728.00
xxii CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
M. Howley (Labor) $ 280.00
Labor 2,426.42
Publications i,445-i7
Postage 229.91
Stationery 210.79
Telephone and Telegraph 144.92
Freight and Express 128.49
Gas and Kerosene 428.36
Coal 1,469.00
Water 189.96
Chemicals and Laboratory Supplies 1,283.56
Agricultural and Horticultural Supplies 209.91
Miscellaneous Supplies 164.42
Botanical Supplies i5-00
Fertilizers 241.14
Feeding Stuffs 102.53
Library and Periodicals 612.28
Tools and Machinery 75.85
Furniture and Fixtures 462.63
Scientific Apparatus 85.47
Traveling by the Board 53.28
Traveling by the Staff 1,149.18
Traveling in connection with Adams Fund Investi-
gations 19380
Tobacco Experiment 1,272.47
Fertilizer Sampling 164.10
Food Sampling 229.83
Insurance 275.25
Insect Pest Appropriation to State Entomologist .... 3,000.00
Contingent 1 19.50
Forestry and Lockwood Expenses 1,899.88
Gypsy Moth Appropriation to State Entomologist . . . 2,500.00
Betterments 795-51 i
Repairs 1,412.90
Grounds 200.00
Rental of Land 130.00
$48,902.33
Analysis Fees on hand, Sept. 30, 1908 863.40
Total $49,765-73
New Haven, Conn., October 14, 1908.
This Certifies that we have examined the accounts of E. H. Jenkins,
Treasurer of The Connecticut Agricultural Experiment Station, for the
year ending September 30, 1908, have compared the same with the
vouchers therefor and found them correct.
William P. Bailey,
Edward S. Roberts,
Auditors of Public Accounts.
CORRECTIONS AND ADDITIONS.
Bulletin 163, page 13. Second paragraph from bottom. The Stearns
Lime Co. offer water-slaked lime at $5.00 in bulk, $6.00 in bags,
and delivered about $7.25. This makes the cost of pure lime and
magnesia 60 cents per 100 pounds, instead of 73, as given in the
Bulletin.
Report, page 4, twentieth line, strike out "Wheeler's Havana Tobacco
Grower."
page II, sixteenth line from the bottom, for 652 read 651.
pages 56, 60, 74. The fertilizer bearing the name of E. B. Clark
Co., Milford, Conn., is made by that firm at its works at
Communipaw, N. J. On pages 56, 60 and 74 of the Report it is
stated that the fertilizer is "made for" E. B. Clark Co. This is
an error.
pages 56 and 57. The price of Olds and Whipple's Home Mixture
is $38.00 per ton, instead of $28.00, as given in the table. The
percentage difference is 13. i.
page 115. Lime-Kiln Ashes, last line, under 18944, for "103" read
54; for "loi" read 39.
page 119. The statement that the L M. P. Plant Food contains
essentially 55 per cent, of nitrate of potash and 45 per cent, of
phosphate of soda is incorrect. It consists essentially of phos-
phate and nitrates of the alkalies. A more particular statement is
not justified by the figures.
page 271, second line from top, for "weight" read weigh,
page 510. The cost price of Manchester's Formula, No. 20767, is
$30.00 per ton, instead of $32.00, and the percentage difference 4.4,
instead of 11.3.
page 528, last line of table, the dealer's price is $45.00 and the
calculated valuation $34.56.
page 534, note, read 530 instead of 529.
page 725, last paragraph. The Hominy Feed sold by M. F. Bar-
ringer, Philadelphia, was shipped with a guaranty of composition,
as required by law.
page 727, second paragraph. After One ex, strike out Ai. The
manufacturer states that the One ex is the lowest grade of
distillers' grains and the mark Ai had never been used in connec-
tion with it.
The feed represented by sample 20710 was not made by the Biles
Co.
To the explanation regarding Dried Distillery Grains on pages 176
and 726 may be added the following note regarding the several
kinds of distillery grains sold by the J. W. Biles Co. :
xxiv CONNECTICUT EXPERIMENT STATION REPORT, I907-I908.
Four ex is the product of alcohol distilleries, consisting of 88 to
90 per cent, of corn residues with 10 to 12 per cent, of "small
grains," chiefly malted barley, with a few oats coming as an
unavoidable mixture in the barley.
Two ex, the product of Bourbon whiskey distilleries, contains 60
to 80 per cent, of corn residues and 20 to 40 per cent, residues of
"small grains," chiefly rye and malted barley, with a few oats.
Rye grains, the product of rye whiskey distilleries, may
consist wholly of rye residues, or of rye and malted barley, with
a few oats, or they may have a large admixture of corn.
One ex grains are from vinegar and yeast factories, containing
about 50 to 60 per cent, of com residues and 40 to 50 per cent, of
"small grains."
page 729, after the words, "Biles' Union Grains contain," insert
cotton seed meal. The manufacturers state that the oat product
is very small in quantity and comes entirely from the oats which
all malted barley contains as an accidental mixture, the ingredients
of the mixture being distillery grains, linseed and cotton seed
meal, hominy feed, wheat middlings and bran and barley malt
sprouts,
page yyy, last line, for "Ridley" read Riley.
State of Connecticut
REPORT
OF
The Connecticut Agricultural
Experiment Station
REPORT OF THE STATION BOTANIST, 1909-1910
G. P. CLINTON, Sc.D.
toNG PART X OF THE BIENNIAL REPORT OF 1909-1910
CONNECTICUT
AGRICULTURAL EXPERIMENT
STATION
REPORT OF THE BOTANIST
1909 and 1910
G. P. CLINTON, ScD.
PAGE
I. Notes on Plant Diseases of Connecticut, 713
A. Diseases in Relation to Weather in 1909 and 1910, . . . 713
B. New Observations on Diseases Previously Reported, . . 716
C. Diseases or Hosts Not Previously Reported, 723
II. Spraying Potatoes in Dry Seasons, 739
III. Oospores of Potato Blight, Phytophthora infestans, 753
ISSUED JUNE, 1911
PART X.
REPORT OF THE BOTANIST FOR 1909 AND I9I0.
G. P. Clinton, Sc.D.
I. NOTES ON PLANT DISEASES OF CONNECTICUT.
A. DISEASES IN RELATION TO WEATHER IN I909 AND I9IO.
Weather Conditions in ipop. The winter of 1908-09 was
not especially severe, so that trees did not show any unusual
injury, except from a couple of ice storms in February, 1909.
These storms so heavily coated the limbs that considerable
damage resulted, especially to shade and forest trees in the
northern half of the state, where the storm was more severe.
The spring of 1909 was rather wet and backward, so that such
fungous troubles as peach leaf curl, apple scab, etc., that gain
their foothold at this time of the year, were unusually prominent.
The summer, however, especially in July and August, like
the two preceding seasons, was one of drought, but it was
broken in August by rains that prevented serious damage to
rriost of the crops. The late fall proved to be very dry. The
first killing frost did not occur until October 13.
Diseases Prevalent in ipop. The following troubles were
conspicuous or unusually injurious during this season. Apple:
Black Rot (Leaf Spot form). Rust, Scab, and Spray Injury
(Bordeaux). Ash: Rust. Chestnut: Bark Disease. Egg
Plant: Wilt (Fusarium?). £/w; Leaf Spot. Muskmelon:
Leaf Mold, Anthracnose. Peach: Brown Rot (spring form on
twigs, etc.). Leaf Curl. Plum: Black Knot. Potatoes: Tip
Burn, Scab. Quince: Leaf Blight. Rose: Rust. Spinach:
Leaf Mold. Strawberries: Powdery Mildew, Winter Injury
(root killing). Tobacco: Calico.
Of the above diseases the leaf spot of elm, which was quite
serious in some places, is discussed later in this Report (p. 717).
50
714 CONNECTICUT EXPERIMENT STATION REPORT, I909-I9IO.
The winter seemed in some way to have weakened the spinach
crop in the vicinity of Greens Farms, for there were reports
that several of the crops there failed because of the subsequent
action of the leaf mold fungus described in the Report for 1905,
page 275. Mr. Joseph Adams, writing of this trouble, said: "1
have a patch of spinach (sown last September in connection with
Mr. L. P. Wakeman), which is practically worthless from a black
spot which covers the leaves. This is the worst I ever saw. This
piece contains about an acre, and we have another piece that is
not quite as bad." This fungus was identified by us previously as
Heterosporium variable Cke., and Professor Thaxter, who
examined these later specimens, writes that it was also described
by Cooke as Cladosporium subnodosum (see Grev. 17: 67. 1889).
Specimens of strawberry plants were received about the
middle of June, both from Essex and Naugatuck, with complaints
that some trouble was killing off certain fields in those places.
Examination revealed no fungus or insect as responsible, but
showed that the rootlets were dead, while the crowns were
still alive. This was a trouble similar to that seen once before,
and discussed in the Report for 1905, page 276. Apparently
there was enough life and food in the crowns to put forth
leaves in the spring, but with the approach of warm weather
these suddenly died off from lack of moisture, etc. The trouble
seems to be due to winter injury of the roots, which had either
suffered from drought the previous year or else had not been
properly protected by snow or mulch during the winter.
Weather Conditions in ipio. The winter of 1909-10 was
not especially severe on the whole, though one or two quite
cold spells were recorded in . January. March proved to be
unusually warm and open, and the spring started early, but
afterwards cool, rainy weather in May kept back the vegetation
so that, as in the preceding spring, it was somewhat backward,
and developed an unusual amount of spring fungous troubles.
There were two very late frosts, in May and early June, that
did more or less injury to fruit blossoms in certain parts of
the state, especially cherries, apples and strawberries, and also
killed or injured the foliage on certain shrubs, etc., especially
in low places. At Windsor we saw small scrub oaks whose
leaves were all killed as if by fire. Some injury to coniferous
plants was also observed, and no doubt much of the russeting
NOTES ON PLANT DISEASES OF CONNECTICUT. 7^5
of apples, so common this year, was traceable in part to these
frosts.
Again the summer proved to be one of drought, thus making
four years in succession that may be so classed. However, like
the preceding one, it was temporarily broken in midsummer by
rains that saved most of the crops from serious injury, though
potatoes, especially early varieties, were a very light crop. The
fall months were unusually dry, and this late drought was not
broken until late in December, so that a water famine threatened
many communities. As in the preceding year, the first fall
frost was delayed until the middle of October, thus favoring
the late crops.
Diseases Prevalent in ipio. Among the most conspicuous
diseases of the year may be mentioned the following. Apple:
Rust, Scab, Frost and Spray Injury. Cherry and Plum: Black
Knot. Chestnut: Bark Disease, Drought Injury. Corn: Smut.
Hollyhock: Rust. Maple: Leaf Scorch. Muskmelon: Mildew
Blight. Peach: Leaf Curl, Brown Rot (chiefly spring infection
of twigs, etc.). Pear: Scab. Pines: Pine-Sweetfern Rust.
Potatoes: Rot (Blight), Tip Burn. Rye and Barley: Powdery
Mildew. Quince: Rust. Sycamore: Anthracnose.
Concerning the spray and frost injury of apples, there
appears a discussion in Part VII of this Report. There was
more peach leaf curl than we have seen before in this state,
and while the wet spring favored twig infection with brown
rot, this did little harm to the mature fruit except during a wet
week in September, when some injury was done to certain
varieties in the vicinity of Wallingford. Potatoes suffered
most from tip burn, but the rains came so that blight developed
slightly on the late varieties and caused some rot of the tubers
for the first time in several years. Blight, in late August and
early September, carried off many of the melon fields that had
not been sprayed.
The effect of successive droughts of the past four years has
begun to be manifest on our shade and forest trees, so that an
unusually large number of them are dying. This is especially true
of the chestnuts, where the blight fungus plays a very important
part on these weakened trees.
On the whole, 1909 and 19 10, because of their dry summers,
were not years in which fungi became especially troublesome,
7l6 CONNECTICUT EXPERIMENT STATION REPORT, I9O9-I9IO.
except those starting during the wet springs. In Parts B and C
of this paper we discuss certain diseases that are new to the
state, or concerning which special information was obtained.
B. NEW OBSERVATIONS ON DISEASES PREVIOUSLY REPORTED.
APPLE, Pyrus Mains.
Spray Injury. Both during 1909 and 19 10 there was con-
siderable injury resulting from spraying apples in this state
with Bordeaux mixture. As previously reported, this injury
was of the nature of leaf spotting and fruit russeting. Experi-
ments conducted in 19 10 with different fungicides to replace
Bordeaux, because of this tendency to injure, showed that there
was danger of serious leaf spotting and subsequent fall with
"One for All" (rate 5 or 6 lbs. to 50 gallons of v/ater), and
also with "Sulfocide" (rate i to 200) when either Paris green
or arsenate of lead was used with it, though the injury with
Paris green when lime was added was lessened. Even without
these insecticides, this strength of "Sulfocide" sometimes pro-
duces more or less leaf spotting. Some leaf injury was also
caused by Bogart's "Sulphur Compound" used at the rate
of i^ to 50. Practically no russeting or leaf spotting was
produced by any of the straight commercial lime-sulphur
sprays, with arsenate of lead added, even at the rate of i^^ to
50, except what occasionally occurred in the shape of sun
scald on the most exposed side of the fruit. While this rarely
occurred, when it did it produced rather serious injury. On
the whole, the straight commercial lime-sulphur sprays were
the most satisfactory as regards least spray injury. For further
information, see Part VII of this Report.
CHESTITUT, Castanea dentata.
Chestnut Bark Disease, Diaporthe parasitica Murr. In
our Report for 1908, page 879, we gave an account of this
trouble. At that time it had been reported in every one of
the twenty-three towns of Fairfield County, and in eight towns
in New Haven County, making thirty-one towns altogether.
At the time of writing this article (March 20, 191 1), its known
distribution is as follows : Fairfield County, twenty-three towns ;
New Haven County, twenty-one towns; Litchfield County,
NOTES ON PLANT DISEASES OF CONNECTICUT. 7^7
fourteen towns; Hartford County, seven towns; Middlesex
County, two towns; Tolland County, three towns; Windham
County, one town; New London County, one town. This
makes a total of seventy-two towns, of which only seven are
east of the Connecticut River, We have no doubt that a more
thorough survey of that region would reveal its presence, in
an inconspicuous way, in quite a few more towns.
This increased distribution in the last three years may indicate
that the disease has spread to those new localities, or it may
mean that a more thorough search has revealed its presence,
and that it has also become more prominent because of the
four years of drought that have occurred, beginning with 1907.
There are those who believe, however, that unfavorable weather
conditions have nothing to do with the prominence of this dis-
ease, which they suspect to be a recent importation into this
country from Japan. If this theory is true, then we are just
beginning to feel the ejffects of its devastation in this state.
Personally, we have not yet found convincing proofs to cause
us to change our views expressed in the above-mentioned Report.
These views, briefly given, are (i) that the fungus is a native,
weak parasite, usually very inconspicuous in its damage, and
therefore rarely noticed; and (2) that the unusual winter of
1904, by severely injuring chestnut trees, gave it a chance to
spring into unusual and sudden prominence, which it has since
maintained and even increased by reason of four successive years
of drought, that have injured not only chestnuts, but many other
trees.
We do not, and never have, questioned its seriousness. Trees
that have been marked in two localities by the botanical and
the forestry departments have uniformly showed injury greatly
in excess of that indicated when first examined. If our theory
is correct, we do believe, however, with the return of several
normally wet years the trouble will gradually grow less rather
than more conspicuous as it should if weakened vitality of the
trees has nothing to do with its development.
ELM, Ulmus americana.
Leaf Spot_, Gnomonia Ulmea (Schw.) Thuem. Plate XXXIV.
During the summer of 1909 several complaints came to the
station of elm trees shedding their leaves where the elm leaf
7i8 CONNECTICUT EXPERIMENT STATION REPORT, I909-I9IO.
beetle had not been at work. The most serious injury seemed
to occur in the vicinity of Chapinville. At the request of Mr.
Walter Angus, manager of the Scoville estate at that place, Mr.
Walden first visited there in August, and as he found no insect
responsible for the trouble the writer made an investigation
early in September to determine if a fungus was the cause of
it. By July, or earlier, some of the trees had almost entirely
shed their leaves, and later put forth a new crop, and these,
when examined by the writer, were quite free from fungous
attack. Other trees, however, not originally so severely injured,
showed the leaves quite badly infected with the above fungus,
and these had been shedding their leaves more or less during
the season. Where the defoliation had been rather severe, the
young branchlets of the season had also frequently fallen off.
While the fungus was present on some trees more than on
others, and while some of the fallen leaves showed no sign of
the fungus, it seemed quite evident, after a careful examination,
that this fungus was primarily responsible for the trouble, but
that drought had helped to exaggerate it. The illustration shows
the condition as regards foliage of one of the trees photo-
graphed by Mr. Walden in August.
The fungus produces very numerous, small, black eruptions
on the upper surface of the leaves, and these often merge more
or less in small groups. In time the specimens show a whitish
or grayish margin around these black cushions, due to the
wearing away of the epidermis. We have been unable to find
any fruiting stage in any of the specimens we have gathered
in different years, as the only known stage produces its asco-
spores on the fallen leaves the subsequent spring. Infection
seems to take place only early in the season, since the trees
early denuded did not have their second crop of leaves attacked
to any extent. Apparently the weather conditions in the spring
determine the character and amount of infection, and these
conditions seem to have been unusually favorable in 1909. In
1910, on the same estate in Chapinville, the fungus did practi-
cally no harm, though the trees bore a smaller crop of leaves,
due to the shedding of the small twigs the previous year and
to the death of others that were severely injured.
Spraying the unfolding leaves with Bordeaux would probably
control this trouble, though the uncertainty of its appearance
would make such a treatment rarely practical.
NOTES ON PLANT DISEASES OF CONNECTICUT. 719
This fungus was placed by Ellis under the genus Dothidella
as D. Ulmea (Schw.) E. & E. It is, however, quite distinct
in its microscopic appearance, as Ellis states, from Dothidella
Ulmi (Duv.) Wint., although the two have ascospores very-
similar. The latter fungus has its perithecia embedded in a
distinct black stroma, and the necks open on the upper surface
of the leaves. The former, by the crowding of the perithecia
together, has something of the appearance of an imperfect
stroma, while the perithecia open on the under surface of the
leaves mature their asci later, and apparently have no other
stage connected with them.
HEMLOCK, Tsuga canadensis.
Hemlock-Heath Rust, Pucciniastrum Myrtilli (Schum.)
Arth. (I. Peridermium Peckii Thuem.) The I stage of this
fungus (see Report 1907, pp. 350, 383), which is not uncommon,
though rarely abundant, in this state on hemlock, has now been
connected by us, through artificial infections, with the H and
III stage of the above Pucciniastrum, which we found in 19 10
for the first time on various species of blueberry and huckleberry.
Pucciniastrum minimum on cultivated azaleas, also found here
(see Reports 1907, p. 392 and 1908, p. 854), is probably not
distinct from this Pucciniastrum.
PEACH, Prunus Persica.
Spray Injury. Sturgis (Report 1900, p. 219) has recorded
spray injury to the foliage of peach by Bordeaux and other
fungicides used in his experiments to prevent peach rot and
scab. He found potassium sulphide to be about the least
injurious fungicide when used at the rate of i lb. to 50 gallons
of water. In our experiments with spraying peaches in 1910,
this strength was used, and very little injury, except shot-holes
in a few of the leaves, resulted. However, when arsenate of
lead (rate of 3 lbs. to 50 gallons potassium sulphide) or Paris
green (i lb. to 100) was added, the most serious injury resulted.
Not only were the leaves badly injured by shot-holes, but in
time they all fell off. Many of the young twigs were also badly
spotted (purplish spots much like those produced by the scab
fungus), arid some were killed. A few young trees were so
severely injured that they finally died.
720 CONNECTICUT EXPERIMENT STATION REPORT, I9O9-I9IO.
Very similar results were obtained when either of these insecti-
cides was used with "Sulfocide." This spray, even when used
without them, at a rate of i to 200 produced more or less injury,
and even some on young trees at i to 400. With both potassium
sulphide and "Sulfocide" the injury resulting from the addition
of the poisons was due to the production of a soluble arsenate
which burned the tissues.
PINE, WHITE, Pinus Strobus.
So-called "Blight." In our Report for 1907, page 353, we
described the white pine "blight," which was general that year
not only in Connecticut but all over New England. We took
the view that it was a physiological trouble due to adverse
weather conditions (such as winter, drought, and frost injuries),
though there were those who believed that it was of a contagious
nature, due to fungous attack. We now have data at hand
to prove that we were correct. In general this disease becomes
evident by the leaves being killed to a greater or less extent
from their tip downward, the dead portion turning reddish
brown, and also by the undersized leaves, which remain bunched,
due to the failure of the branches to lengthen out.
That the disease is not contagious was suggested strongly in
our previous studies, since leaves on one tree may all be badly
affected while those of an adjacent tree show no signs of the
trouble. This noncontagious nature has been clearly proved by
observations made in the station's forest plantation on a lot of
white pine trees eight years old, in 1910, from planting. At
our request the forester, Mr. Hawes, early in the spring of
1908 had all the diseased trees of this plot marked by permanent
stakes. There were one hundred and twenty-four of these so
marked, but it seems quite likely that some few that showed
the disease slightly at the time were not included. We examined
them that fall, and found that their condition on the whole
seemed somewhat improved, and that there was no general
increase of the trouble, though some trees that had not been
marked showed signs of the disease. In July, 1909, and again
in November, 19 10, careful examinations were made of the
plot, and the condition of each diseased tree noted. The com-
parative condition of these trees as regards foliage is shown
in the following table :
NOTES ON PLANT DISEASES OF CONNECTICUT. 72 1
Diseased, but
Date of not marked Not
Examination in 1908 Dead Improved Improved Cured Total
July, 1909 24 5 54 38 21 142
Nov., 1910 18 6 9 65 44 142
This shows that there has bten gradual improvement since
the trouble first showed in 1907, and that there has been practi-
cally no subsequent spreading of the trouble. That is, in 19 10
there were only eighteen trees showing the disease, among the
3,000 to 3,200 in the plot, that did not show it in the spring of
1908. Of these eighteen, at least thirteen were included as
questionable; that is, there was not positive evidence that it
was this trouble, as the leaves were only slightly affected. No
doubt, too, some of these were trees that were not marked
originally because they were not badly injured. It is also quite
probable that some were trees whose leaves were injured by
the frosts of 1910, of which we shall speak later, as the injured
leaves were often largely on lower branches. Finally, there
was no relationship in position between these trees and those
badly diseased.
Concerning the effect of the so-called "blight" on the sub-
sequent growth of the trees, we may state that those that were
very badly injured have either died, or remained so stunted
in growth that their subsequent usefulness is quite doubtful.
Others that were rather severely injured have made some
growth, and their foliage condition, especially as to color, has
improved considerably, though the leaves often remain more or
less stunted and bunched. Those least injured have recovered
their normal leaf appearance, but are still somewhat backward
in their growth. Some few seem to have almost entirely recov-
ered from the effects, and are scarcely to be distinguished in
size and appearance from the surrounding trees that were not
injured.
Concerning the cause of the sudden appearance of this
"blight" in 1907, we are now quite convinced that it was due
to the severe frosts that occurred on May 11 and 21 of that
year. We mentioned these as a possible cause in our previous
Report, but at that time we had no proof as to their connection,
as the "blight" was not called especially to our attention until
August. In 1910, however, we saw the same trouble produced
on certain pines by the late frosts of May and June of that
year. Soon after these frosts we found the leaves of scrub
722 CONNECTICUT EXPERIMENT STATION REPORT, I909-I9IO.
oaks in certain regions entirely killed by the frosts, just as had
been the case with the leaves of sycamore trees in 1907. In
1910, however, the frosts were much more local in their effects,
and in a given region often killed the leaves only on the lower
trees and the shrubs, especially those in low places. Shortly
after the last of these frosts we visited the white pine planta-
tions on the Whittemore estate at Middlebury, and here we
found not only small oaks and other trees in low spots with
injured foliage, but also the young pines in these low places
showed "blight" injury on the tips of their leaves. Often a
difference of only a few feet in the level of the ground on
which these stood determined whether or not they were injured.
We have also noted elsewhere in this Report injury by these
frosts to pine seedlings in the seed beds. Whether or not a
pine tree is injured by the late frosts seems to be determined
by the state of development of the foliage at the time, as well
as by the lay of the land and the character of the frost.
Previous to 1907 we had some few complaints of pine "blight,"
which we may attribute to winter injury of the roots, and no
doubt drought or other injury to the roots, if severe, produces
a similar effect. Hartig, in his Diseases of Trees, English ed.,
p. Ill, notes a similar "blight" trouble in Europe, due to frost
and drought injury.
PLTJM, Prunus sp.
Bacterial Spot, Pseudomonas Pruni Sm. This has been
reported here before on peach, causing spots on the leaves, and
on the plum, causing large black spots on the fruit. In July,
1910, it was seen at the Ives farm, Meriden, for the first time
causing a shot-hole spotting of plum leaves, similar to that
not uncommon on the peach.
SPRUCE, NOEWAY, Picea excelsa.
Smoke Injury. During the summer of 1910 the writer saw
young spruce trees at East Rock Park, New Haven, that had
been injured by smoke from a brick kiln about half a mile
distant. The injury occurred suddenly on a day when the atmos-
pheric conditions were just right for blowing the smoke among
the trees. The young leaves of this year were killed and sub-
sequently dropped off, but those of the previous • year were
NOTES ON PLANT DISEASES OF CONNECTICUT. 723
not injured. Some other conifers were also slightly injured,
but the deciduous trees escaped injury, though in the vicinity
of the kiln the maples and other trees are sometimes injured.
Previous smoke injury, complicated with drought injury, to
asparagus fields in the vicinity of this kiln, was mentioned in
our Report for 1908, page 858, and similar injury is claimed
to have been caused again this year.
C. DISEASES OR HOSTS NOT PREVIOUSLY REPORTED.
APPLE, Pyrus Mains.
Fruit Spot, Cylindrosporium Pomi Brooks. Plate XXXIII a.
In our Reports for 1905, page 264, and 1907, page 340, we
described a fruit speck of apples that formed small, brownish,
spots in the skin of apples, being especially prominent after stor-
age. Cultures proved this trouble to be of fungous origin, but as
these cultures did not produce a fruiting stage of the fungus, we
were not sure of its identity.
More recent study has shown that there are three fungi that
occur in fruit spots or specks of apples. One of these is the
black rot fungus, Sphaeropsis Malorum, which is more commonly
known not as a spot trouble, but as a general rot of the fruit,
especially on summer and fall varieties following insect injury.
This fungus is the one that we have most commonly isolated from
the fruit specks of market apples. Ordinarily it does not fruit
in the culture media on which we have grown it, and so it was
probably largely responsible for the fruit speck we describe in
the above reports, though Cylindrosporium Pomi was possibly
present in some cases. Besides the black rot, we have also occa-
sionally isolated a species of Alternaria which seems to be respon-
sible for speck injury, though we have as yet made no inoculation
tests to prove this.
. The third fruit spot, which we have seen frequently on the
fruit before it was gathered from the trees, as well as afterwards,
is that caused by Cylindrosporium Pomi, which was described a
few years ago as a new species by Brooks, who found it respon-
sible for a serious spotting of apples in New Hampshire. This
fruit spot on the market apples is usually very difficult to distin-
guish from that of the black rot. Perhaps the black rot fungus
724 CONNECTICUT EXPERIMENT STATION REPORT, I909-I9IO.
may finally crowd it out in many cases. However, on certain light
skinned varieties, especially seedlings, it shows in the summer as
small spots in the skin having a decidedly pinkish or reddish
purple color. We have seen roadside seedlings made very con-
spicuous by it in late fall. In storage the color of the spots is
darker. So far we have not seen the fungus in fruit on these
superficial spots, and ordinarily they do not seem to reach any
considerable size, except perhaps when developed further by the
presence of the black rot fungus. In one instance we isolated
this Cylindrosporium from market quinces, a new host, and we
have frequently seen similar spots, showing no fruiting fungus,
on quinces before and after picking.
On our oat juice agar medium the fungus forms a large, yeast-
like, pinkish colony with no aerial growth, but producing an
abundance of spores. With age it turns a darker color, sometimes
black, though in such cases it may be due to the presence of
another fungus frequently associated with it, which we have
isolated, but whose identity has not yet been determined.
AZALEA, Rhododendron indicum.
Pocket Curl, E.vobasidium Vaccinii (Fckl.) Wor, Plate
XXXIII b. Galls and hypertrophy caused by this or closely
related species are not uncommon in this state on various wild
species of the heath family, but this fungus on a cultivated
species was called to our attention for the first time in the fall
of 1909. Specimens of the above azalea, purchased a few months
previously for a private greenhouse, were very badly injured.
These plants were apparently infected when purchased, having
been grown out of doors in a neighboring state, but did not
show the trouble at that time. The disease appeared on th'b
leaves, usuahy involving the apical part and causing a decided
thickening of the tissues. This infected part covered more or
less of the leaf, which often became decidedly concavo-convex,
as shown in the illustration. The infected tissues were quite
sharply marked off from the healthy part, both by their dis-
tortion and by their whitish color, being eventually covered by
a mealy coating of spores, etc.
Cultures were made, and a fungus obtained that seems to
be a conidial stage of this fungus, though its identity has not
been thoroughly established.
NOTES ON PLANT DISEASES OF CONNECTICUT. 725
The question whether or not the various forms of Exohasidium
found on the different genera of the heaths are distinct or not
has not been definitely decided. Often their macroscopic
appearance on different hosts is quite distinct, but as Richards
(Bot. Gaz. 21: loi. 1896) succeeded in producing the ordinary-
leaf form from spores of the unusual large bladder form on a
different host, it looks to the writer as if these differences were
largely due to the age or parts of the host infected. Shirai
has described two species of Exohasidium on Rhododendron
indicum, to one of which our fungus possibly may belong if
they are really distinct, though the spore measurements do not
seem to agree entirely.
CELERIAC, Apium graveolens var. rapaceum.
Leaf Blight, Cercospora Apii Fr. We have reported before,
on celeriac, the leaf spot due to Septoria, but not this fungus.
Both produce brownish or grayish spots of considerable size
on the leaves, often causing them to turn yellow and die pre-
maturely. They are often found associated, the Cercospora
being distinguished by its minute threads arising from the
surface of the leaves, while the Septoria forms small, embedded,
black specks.
CHESTNUT, Castanea sps.
Chestnut Bark Disease, Diaporthe parasitica Murr. Speci-
mens of this serious disease of our native chestnuts have been
collected on the Japanese chestnut, Castanea japonica, in a local
■ nursery. Dr. R. T. Morris, who grows a large number of
varieties of chestnuts on his Stamford farm, also reports (Conn.
Farmer, March ii, 1911, p. 2) that, besides the Japanese species,
the European species, Castanea sativa, and the American Chin-
quapin, Castanea pumila, have been more or less subject to this
blight at this place. See page 716 of this Report.
CHESTNUT, Castanea dentata.
Powdery Mildew, Microsphcora Alni (Wallr.) Wint. We
have not reported this host because we have found the mildew
on it previously only in the woods, but in September, 1907,
it Avas observed on cultivated trees in a small nursery at Storrs.
It forms evident, mealy, whitish growths, in which the perithecia
726 CONNECTICUT EXPERIMENT STATION REPORT, I909-I9IO.
are embedded as small black specks, chiefly on the upper surface
of the leaves. It is not an important disease of this host.
CHIVES, Allium Schccnoprasum.
Rust, Puccinia Porri (Sow.) Wint. This rust was collected
by Dr. Britton during June, 1910, on chives in his garden in
Westville, where it was doing considerable injury to the plants.
Both the II and III stages were present, the former showing
as minute, reddish, dusty pustules, and the latter as black, granu-
lar ones, more permanently covered by the epidermis. The
leaves, when fairly abundantly infected, turned yellow and died
prematurely. I have not seen any account of injury by this
rust to cultivated species of Allium in this country, though in
Europe it is not uncommon. Worthington Smith, in his Dis-
eases of Field and Garden, page 39, mentions it, under the name
Puccinia mixta Fckl., as causing serious injury to a crop of chives
in England. There is more or less difficulty in deciding the
proper genus of this fungus, since the telial spores in some
specimens on certain hosts are almost or entirely single-celled,
and so properly come under the genus Uromyces; other speci-
mens show these spores largely two-celled, and so place it more
properly under the genus Puccinia. Our specimens run more
nearly to the former type, as not over one or two per cent,
of the spores are two-celled. Winter considered the two as
a single species, and we have followed him. Other writers
place the single-celled form under Uromyces ambiguus (DC.)
Fckl., and the form with most of its spores two-celled under
Puccinia Porri, as given here. The rust on chives in Europe
is generally reported under this latter name. Our specimens,
however, have fewer two-celled spores than those we have seen
from Europe on the same host. Puccinia Allii (DC.) Rud.,
also on species of Allium, is quite a different fungus.
CORNFLOWER, Centaurea Cyanus.
Rust, Puccinia Cyani (Schl.) Pass. Both the II and III
stages of this rust were found, causing severe injury to the
cornflowers in the writer's garden during the summer of 1909.
The sori, while numerous, form rather inconspicuous, dusty
outbreaks on both surfaces of the leaves and on the stems
NOTES ON PLANT DISEASES OF CONNECTICUT. 727
Apparently this fungus has rarely been reported in this country.
Another rust, P. Centaurece DC, also occurs on other species
of Centaurea both here and in Europe. Both of these species
have frequently been grouped with other Puccinias, the species
here reported being usually placed under P. suaveolens, along
with the rust on Cnicus now commonly known by that name.
ELM, Ulmus sp.
Anthracnose^ Septoglceum Ulmi (Fr.) Br. and Cav. This
fungus was found on an escaped seedling of Ulmus campestris
(apparently) along the roadside in Centerville. It produces
numerous, minute, at first yellowish but finally reddish-brown
spots on the upper surface of the leaves, while below the
fruiting stage shows as minute, glistening, yellowish globules.
The fungus has usually been reported as Phleospora Ulmi
(Fr.) Wallr., but the writer agrees with Briosi and Cavara
that it belongs more properly under the above genus. Cylindro-
sporium ulmicolum Ell. and Ev. possibly is not distinct from
this species, as its description is very similar. This Septoglceum
is thought by some writers to be the spermagonial and Piggotia
astroidea B. and Br., the pycnidial stage of Dothidella Ulmi
(Duv.) Wint. [Phyllachora Ulmi (Duv.) Fckl.], though neither
of these two stages were found associated with our specimens.
The asco stage of Dothidella Ulmi, while not uncommon in
Europe, does not seem to have been reported in this country
except the doubtful specimen sent by Torrey to Schweinitz.
GOOSEBERRY, Ribes sp.
Rust, ^cidium Grossularice (Pers.) Schum. This rust was
found on the leaves of a species of gooseberry, apparently
escaped from cultivation, in the woods of an abandoned farm
belonging to the water company at Ansonia. The fungus forms
rather small clusters of cup-shaped fruiting bodies on the under
surface of the leaves, producing discolored spots above. It is
probably connected with some species of Puccinia on Carex
as its mature stage, as has been found to be the case with several
European forms on Ribes sp. We have never seen this ^cidium
causing much harm to its hosts, and it seems to occur chiefly
on the wild species.
51
728 CONNECTICUT EXPERIMENT STATION REPORT, I9O9-I9IO.
HOESECHESTNTJT, ^sculus sps.
Powdery Mildew, Uncinula flexuosa Pk. This mildew was
found on a species of Msculus with colored blossoms, on an
estate at Chapinville in the fall of 1909. The conidial stage
formed a conspicuous whitish coating on the upper surface of
the leaves, while the perithecia were less prominent, though
abundant, on the lower surface. The fungus has not been
reported by us before, though Thaxter collected it in New
Haven in 1888 on another cultivated species, ^sculus Hippo-
castanum.
MONKSHOOD, Aconitum Fischeri.
Stem Rot, ? Hypochnus sp. In our Report for 1907, page 351,
we described this stem rot, which was found on a variety of
herbaceous plants in a local nursery. This year it was sent
to us from Westbrook, where it was injuring specimens of
larkspur, one of the hosts reported before. Since our first
report we have also found it on monkshood, in the same nursery
where it was found originally. So far we have been unable
to identify the fungus, as our cultures form only the sclerotial
stage — small, reddish, usually subspherical bodies about 2 to
5 mm. in diameter. We have a similar fungus from potato
stems, forming considerable small sclerotia, that was given to
us by Morse of the Maine Station. While in Japan, we saw
in Professor Hori's laboratory artificial cultures of a number
of these sclerotial fungi, which he had described as species
of Hypochnus, though we are not sure of this identification
from what we have learned concerning them.
PINE, Pinus sps.
Pine-Oak Rust, Cronartium Quercus (Brond.) SchrcKt.
(L Peridermium cerebrum Pk.) On specimens of jack pine,
Pinus Banksiana, in the nursery of the station forest plantation
at Rainbow in the spring of 1910, Mr. Filley, and later the
writer, collected the I stage of this fungus. These seedlings
were about four years old, and had been brought in 1908 from
Michigan, where no doubt they were originally infected, as
this fungus in none of its stages has ever before been found
in this state. The fungus on the pine forms conspicuous
NOTES ON PLANT DISEASES OF CONNECTICUT. 729
swellings, usually globular in shape, and in early spring the
fruiting stage shows under the denuding bark as orange-colored,
dusty spore masses, with the peridia rarely forming distinct cups,
as in the next species. The II and III stages occur on species
of oak. So far as could be seen, these did not appear on
the oaks in the vicinity, and as all the infected pines were
destroyed, it is not likely to become established there. Infec-
tion experiments made in the laboratory from the I stage,
however, produced the III stage only very readily on seedlings
of both red and white oaks. So far this fungus has not done
much damage elsewhere on either host. See Plate XXXVI b.
PiNE-SwEETFERN RusT, Cronavtium Comptonice Arth. (I.
Peridermium pyriforme Pk.) In the Report of 1907, page 380,
the writer reported the I stage of this rust on both Pinus rigida
and P. sylvestris from this state. It had become established
on the latter host in the station forest plantation at Rainbow.
In.ipio it was found there also on Pinus rigida, P. austriaca,
and P. maritima. It was also found in its II and III stages
on the sweetfern, to which it had spread since its introduction.
Apparently most of these pines had become infected in their
nursery beds at Poquonock before transplanting here some
years ago, as thousands of seedlings of Pinus rigida grown from
the first in their vicinity showed practically no infection. The
specimens of P. maritima, however, had become infected there
in their seed bed, yet we could find no infected sweetfern in
their immediate vicinity this year. In order to prevent further
spread of the rust, all infected pines were destroyed or the
infected branches cut off, and the forester had all the sweetfern
in the vicinity mowed off. Most of the pines, having the fungus
on their main trunk, were of little value. Where infection
takes place after the pines are a few years old, the damage is
not likely to be nearly so severe as when it takes place in the
seed bed. See Plate XXXVI c.
PIITE, WHITE, Pinus Strobus.
Drought Injury. In the fall of 1909, Mr. Spring noticed a
few spots in one of the seed beds at the station forest plantation
where the white pine had been entirely killed out for the space
of a few inches. Specimens of these and some of the adjacent
living pines were brought to the writer at the time for examina-
73° CONNECTICUT EXPERIMENT STATION REPORT, I909-I91O. .
tion. On the stems of the dead pines, and also somewhat on
the Hving ones, was a conspicuous felt of mycelium of a
hymenomycetous fungus which Professor E. A. Burt determined
as Coniophora byssoidea (Pers.) Fr. At first we thought that
this fungus was responsible for the death of the seedlings, but
we were unable to find any account of injury caused by it
elsewhere. A bunch of these young pines was kept in a crock
in the greenhouse for several months, and there was no indi-
cation that the fungus injured the healthy young pines on which
it originally occurred, or that it spread further. The fungus
evidently ran up on the stems merely as a saprophyte, from
various leaves on the ground on which it also occurred. The
pines in the seed beds were probably killed by the drought,
which was so severe in 1909, and the dead and injured seedlings
offered a better condition for the development of the fungus
than the surrounding mulch of leaves, as Professor Burt states
that out of nine specimens in his herbarium seven are on pine
and two on spruce. See Plate XXXV a.
Frost Injury. Plate XXXV b. In examining the seed beds of
white pines at the station plantation at Rainbow in the fall of
1910, the writer found sn^all spots scattered in the beds where
the leaves of this year's growth had been killed. The injury
was evidently caused by the late frosts of May and June of
that year, as these had killed the leaves of the scrub oaks in
this vicinity, as observed at the time. The young pines had
developed their terminal branches an inch or two in length,
and these had been severely injured or killed by the frost on
both the one- and two-year-old seedlings. The leaves of the
previous year remained uninjured. Afterwards these injured
pines put out several lateral buds from or below the injured
tip, but even as late as November i, when seen by the writer,
these had not usually attained a length of half an inch. This
injury had severely stunted the growth of the plants during
the season, as is indicated by the photograph, which shows
one of the uninjured plants, besides several of the injured ones
of the same age. A few seedlings of Pinus montana were also
injured, but not so extensively as were those of the white pine.
PiNE-CuRRANT RusT, Cronartium ribicola Waldh. (I. Peri-
dermium Strohi Kleb.) Plate XXXVI a. In our article on Heter-
cecious Rusts of Connecticut, published in the Report for 1907,
NOTES ON PLANT DISEASES OF CONNECTICUT. 731
page 374, we mentioned this rust as one likely to be brought
into this state on imported white pine seedlings from Europe.
Its introduction really occurred sooner than was anticipated.
Mr. F. A. Metzger first found specimens on a lot of three-year-
old seedlings from Germany that had been imported by our
State Forester for Mr. C. F. Street, and planted at Wilton.
Mr. Metzger, who was employed to set them out, found in the
10,000 seedlings from fifty to one hundred that were infected
with the rust. He brought specimens to the station the last of
April, 1909, but as the writer was in Japan at that time, nothing
further was done.
In the meantime Messrs. Metcalf and Spaulding, of the U. S.
Department of Agriculture, who had been looking up infected
seedlings in other states, came to this state about the middle
of June, and with the forester examined the plantations of the
New Haven Water Company at West Haven and the Ansonia
Water Company near Ansonia, and found a few very suspicious
specimens at these places. Arrangements were made soon after-
ward by which Mr. Spaulding and Mr. Graves for the Govern-
ment and the botanical department for the station undertook
during July to go over the plantations in the state where white
pine seedlings had been imported from Europe, and inspect them
for this rust, and to destroy any infected seedlings, if found,
and any wild gooseberries or currants in their vicinity, as the
II and III stages occur on the latter as alternate hosts. It
was really then too late in the season to find the fungus on
the pines, except far past its prime. However, twenty-four
plantations, including about 580,000 seedlings, were inspected,
and very suspicious or positively identified infected specimens
were found at two additional places; viz., at the Plant estate
plantation at East Lyme and at the Groton Water Company
plantation at Poquonock. In none of the five places where
signs of the pine rust were found were more than a dozen
specimens seen, except at the Street plantation, where the dis-
eased plants were noticed as they were being set out. A
descriptive letter concerning the rust and its reputation was
sent to all those who had used imported seedlings.
In 1910 the botanical and forestry departments of the station
undertook to again go over these and other plantations, beginning
early in the season, as soon as the rust ordinarily makes its
732 CONNECTICUT EXPERIMENT STATION REPORT, I909-I9IO.
appearance. During May and June four inspectors visited
twenty-six plantations, inspecting about 425,000 seedlings, and
made very careful examinations for the rust, in many cases
examining every individual seedling. In spite of this thorough
examination, not a single rusted plant was found! No doubt
the severe drought of the preceding year had killed off those
seedlings weakened by the rust, if such existed. Of course
it is possible that examination another year might reveal a few
rusted plants, as it is usual for the seedlings to go one or
possibly more years after infection, before the secial stage of
the rust appears on them.
During the years 1907, 1908 and 1909, there were imported
into the state, chiefly from Germany, under the supervision of
the station's forestry department, about 640,000 white pine
seedlings, which were set out in fifty-five different localities,
and private individuals have imported at least 100,000 more.
All of these seedlings, except about 95,000 set out mostly in
small lots in twenty different localities, have now been inspected
once or twice for the rust. No doubt, too, at the time they
were set out the men would have discarded any specimens
showing evidence of the rust. In all of the plantations exam-
ined, watch was kept for any signs of currants or gooseberries
in the vicinity of the pines, and these were destroyed when
found. Fortunately, species of Ribes in a wild or escaped state
are comparatively rare here, so that even if this rust occurred
on the pines, it would be much more difficult for it to pass
to these hosts than in some of the more northern states
where they are more frequent. In 1910 the station did not
import any white pines because of the danger of bringing in
this rust, and only one lot, to our knowledge, was imported by
others. Examination of these showed no signs of the rust.
From now on it is probable that most of the seedlings set out
will be native grown stock, as plenty of this seems to be in
evidence at fair prices. There does not seem to be much likeli-
hood, therefore, that the rust will obtain a foothold in the
state, though watch will still be kept for it. Anyone finding
suspicious specimens should send them to the station for exami-
nation.
Infected white pine seedlings, out of the season vv^hen the
fruiting stage appears, may be recognized in a general way
NOTES ON PLANT DISEASES OF CONNECTICUT. 733
by the somewhat fusiform swollen stems and by the bunching
of the leaves, shown by the halftones in Plate XXXVI a. Not
all swellings of the stem, however, are due to rust, as insect
and other injuries may produce such distortions in young seed-
lings. During the months of May and June the fruiting stage
shows on the swollen stems as small, white, oblong blisters
that upon rupture reveal an orange mass of spores. These
gradually wear away, and then positive evidence of infection
is more or less difficult. The mycelium remains in the infected
tissues, gradually spreading to the new growth, and renews its
fruiting stage each spring, unless the death of the host intervenes.
The spores produced on the pine do not spread the disease to
other pines, but develop two other spore stages on both goose-
berries and currants, the last stage carrying the fungus back
to the pines.
Many writers consider this rust as a very serious menace
to white pines. The writer is not so much afraid of it in this
state because of the scarcity of the alternative hosts, and also
because it looks to him as if most of the damage comes from
the use of infected seedlings, which we should be able to largely
eliminate here. Such infection as might occur after the pines
once got a good start in the forests we are inclined to believe
would be rare, and not nearly so injurious to the host. We
have heard of one large importer of white pines who intends
also to import a large number of currant bushes for commercial
purposes. Such a condition offers a chance for the rust to do
considerable harm if it once gets started in either of his plan-
tations.
The native pine-sweetfern rust, which we describe elsewhere,
seems to us to be just as virulent as this rust, and one much
more likely to spread generally here, on account of the frequency
of its alternate host, the sweetfern. Yet, with the exception of
the plantation at Rainbow, where pines were infected in the seed
beds, we have seen and heard of no damage by this rust. This
rust does not occur on the white pine, though it has several
other species for its hosts.
PRIVET, Ligustrum vulgare.
Anthracnose, Glceosporium cingulatum Atk.* Mr. Coe, of the
Elm City Nursery Company, first called the writer's attention
734 CONNECTICUT EXPERIMENT STATION REPORT, I909-I9IO.
to this disease on a variety of privet called italicum, which was
imported from France in the spring previous to our examination
in the fall of 1910.' The fungus causes diseased areas on the
stem and branches, which are not very conspicuous, being slightly
sunken and a different color, but when these cankers entirely
girdle the branches, the leaves and finally the whole branch above
die, and the trouble becomes very evident. The injury at this
place was quite noticeable, through the dead branches and one
or two dead bushes, but probably the shock of transplanting
may have weakened the plants so that the trouble was more
conspicuous than it would be under more favorable conditions
for the host.
When Atkinson originally described this fungus (Bull. 49,
Cornell Exp. Sta.) in 1892, he said nothing about the injury
to the host, and we have seen no reference where it is said
to have caused conspicuous injury, though it seems to be capable
of it. Atkinson obtained cultures of the fungus, described the
conidial stage, and suggested that it had a mature stage, which
his student, Miss Stoneman, later described (Bot. Gaz. 26:
loi. 1898) as belonging to the genus Gnomoniopsis, now known
as Glomerella.
Cultures of the fungus were easily obtained by the writer
from the cankers, and these produced both the conidial and the
asco stages. Miss Stoneman notes the presence in the cultures
of setae connected with the conidial stage, but did not find these
on the host. The writer, however, found some of these setae
with the conidial stage on the host.
RASPBERRY, Ruhus strigosus.
Rust, Puccinastrum arcticum var. americanum Farl. This
rust, which was described a few years ago by Professor Farlow
(Rhodora 10: 13. 1908), has ordinarily been confused with
the uredo stage of Kueneola alhida, as, like that species, it forms
very small orange outbreaks on the under side of the leaves.
Microscopically, however, the two are quite distinct. The uredo
stage was sent to the writer from Stamford in September, 1909,
on cultivated raspberry, this being the first time it has been
found in the state. It apparently did little harm to its host.
The ^cial stage 'is unknown, though it may be Peridermium
balsameum on the balsam fir.
NOTES ON PLANT DISEASES OF CONNECTICUT. 735
RYE, Secale cereale.
Powdery Mildew, Erysiphe graminis DC. In our Report
for 1903 we listed the conidial stage of this mildew on cultivated
barley. In 1910 specimens on rye were received from J. F.
Shepard, of New Haven, and others were collected by the writer
at the station farm at Centerville, these being the first collections
on this host in the state. In the latter locality the perithecial
stage was very conspicuous and abundant on rye, but on barley
was practically absent. Considerable injury was caused to both
these hosts through severe infection of the leaves, which died
prematurely. Apparently the season was favorable for an
unusual development of the fungus. It forms an evident
grayish felt in small clusters, thickly covering the leaves, and
the perithecia, when produced, show as small but evident black
specks embedded in this. As usual with this species, none of
the asci matured their spores on the living plants.
SaUASH, Cucurbita Pepo.
Chlorosis. In previous Reports we have mentioned chlorosis
troubles of Lima and string beans, muskmelon, tobacco and
tomato. Of these so far we have been able to prove only those
of tobacco and tomato to be infectious, that is, capable of
producing the trouble in healthy plants when juice from the
chlorosis plants is placed on the young leaves. In June, 1910,
we saw plants of summer squash in cold frames at the Farnham
farm in Westville that were subject to a chlorosis trouble,
though from its appearance it did not impress us as being
of an infectious nature. The leaves were quite prominently
streaked with irregular areas of lighter yellowish-green, the
normal green color remaining more commonly around the veins.
The cause of the trouble was not determined, though possibly
too much manure in the beds may have had something to do
with it.
SWEET PEA, Lathyrus odoratus.
Powdery Mildew, Erysiphe Polygoni DC. Previous to this
we have reported in this state only one trouble of the sweet pea ;
viz., a rot disease. This powdery mildew forms a mealy, whitish
growth on the leaves through the production of its conidial
stage, but the perithecial stage was not found. Apparently the
736 CONNECTICUT EXPERIMENT STATION REPORT, I909-I9IO.
mildew is not a conspicuous parasite of the sweet pea, as it
is not listed on this host in the more prominent works on the
mildews. The absence of the mature stage renders its deter-
mination somewhat doubtful, but as the conidial stage agrees
with the above species, and as this has been reported on several
other species of Lathyrus, it is more likely to be this than any
other species.
WALNUT, ENGLISH, Juglans regia.
White Mold, Microstroma Juglandis (Ber.) Sacc. We have
reported this fungus before on cultivated specimens of our
native butternut. It was sent to the writer in July, 1909, by
Dr. R. T. Morris on the variety Kaghazi of the English walnut,
grown on his farm at Stamford. While this fungus forms
conspicuous white patches on the under sides of the leaves, it
is not usually a very serious pest.
WHEAT, Triticum vulgare.
Stinking Smut, Tilletia foetens (B. and C.) Trel. Very
little wheat is grown in this state at the present time, so that
this smut has not been collected here in the fields. However, it is
of economic importance in another way. At least four times
during the last few years samples of commercial wheat feeds,
usually in the shape of middlings, have been sent to the station
for examination because animals refused to eat the feed. Two
of these samples have come from feed men and two from farm-
ers. A microscopical examination in each case has shown the
presence of the spores of the stinking smut. In a sample
recently received from Mr. R. A. Jones of Bethlehem, the smut
spores were unusually abundant. Mr. Jones said that the mid-
dlings had been fed to hogs, that it made them sick, and that
some of them refused to eat more. After changing to other
food the hogs got over their trouble.
Feeds that contain these spores indicate not only that they
are made from middlings, but from badly smutted or injured
wheat, which would be of no value for flour. Whether or
not the smut spores are themselves the injurious principle might
be questioned, but there seems to be no question, if they are
not, that the action of this fungus, or its opening the way for
NOTES ON PLANT DISEASES OF CONNECTICUT. 737
bacteria to act, produces in the plant tissues deleterious products
that injure or render dangerous their use for feeding purposes.
Tubeuf, in the English edition of his Diseases of Plants, page
306, says concerning Tilletia Tritici (a very closely related smut,
also found in grain in this country) : "The smut also possesses
poisonous properties which make flour contaminated with it
dangerous to human beings and the straw or chaff injurious
to cattle. . . . The symptoms in the few cases of disease observed
do not agree very closely. A paralyzing effect on the centers
of deglutition and the spinal cord seem to be regularly present.
As a result one generally finds a continuous chewing movement
of the jaws and a flow of saliva, also lameness, staggering,
and falling. Cattle, sheep, swine and horses are all liable to
attack."
McAlpine, in his Smuts of Australia, page 8i, records a case
in which six hundred and fifty Leghorns dropped in a few days
from a daily average of one hundred eggs to sixteen when they
were fed on smutted wheat, and when this was stopped and
clean wheat substituted, they regained in three weeks an average
daily yield of eighty eggs. He also records an experiment with
pigepns in which one pair was fed smutted wheat for twenty-
two weeks, while the other pair was fed sound wheat. The
doves fed good wheat laid seven eggs during this period, while
the others laid only two. Both pairs of pigeons at the start
were in good plumage, and the pair fed on good wheat retained
the good plumage and was fat at the end of the experiment,
while the other pair was in poor condition, with the feathers
all standing out.
While writing on this subject of deleterious animal foods,
we might mention that we have also occasionally had whole
oats sent in that horses refused to eat. We have never found
any fungus that might be the cause of a musty condition of
these oats. It has been thought that in these cases the
oats were bleached by some sulphur process, and that this had
left them unpalatable to the horses. We have also recently
heard of a case where certain farmers last year purchased oats
for feeding purposes, and as they looked plump and white they
were also used for seed. None of the fields sowed with these
oats came up, and as they were to serve as a cover crop for
grass seed, the latter also failed. It seems quite probable that
738 CONNECTICUT EXPERIMENT STATION REPORT, I909-I9IO.
these oats had been sulphured, and their vitality entirely
destroyed. Seed at all suspicious should be sent to the station
to have its germination tested.
We have also had one or two cases called to our attention
recently where animals have been made sick and some have
died from eating silage. In such cases the silage had not been
properly made and had become moldy, and the fungous growths
no doubt had produced poisonous products in the decomposition
of the silage. Similar troubles have been noticed elsewhere
from feeding moldy silage (see Pammel's Manual of Poisonous
Plants, p. 24).
SPRAYING POTATOES IN DRY SEASONS. 739
II. SPRAYING POTATOES IN DRY SEASONS.
General Considerations.
Object. In our Report for 1904, page 363, we gave the results
of spraying potatoes during the three wet years, 1902 to 1904,
when bhght was unusually severe in this state. The sprayed
parts of these fields showed increased yields, varying from 18
up to 108 per cent., according to the season, thoroughness of
the spraying, etc. During these experiments certain points came
up for consideration upon which we had no data to base con-
clusions. For example : ( i ) Would manure tend to increase
the amount of rot in a field badly blighted over the amount
of rot in the same field in which a commercial fertilizer was
used? (2) Would the use of the same land for two or three
years in succession tend to increase the amount of rot in the
successive crops, other things being the same; and would blight
tend to appear earlier in such a field? (3) Would ridging the
rows help to prevent the blight spores from being washed down
to the tubers, and so decrease the per cent, of rot as compared
with level culture under the same conditions?
In order to answer the above questions, the writer started a
series of experiments in 1906, which were carried on for the
four years ending in 1909. Unfortunately for the primary
objects of the experiments, these years proved to be ones in
which blight did very little harm in this state. In fact, in three
of these years we were unable to find any of the blight fungus
on potatoes in this experimental field, and in the other year
it was so scarce as to cause practically no harm. However,
while the main objects of the experiments remained unanswered,
we still obtained data regarding spraying in dry seasons, also
some data regarding scab, which we present in this paper.
Conditions of Experimentation. The experiments were carried
on each year on the same plot of ground; viz., two-thirds of
an acre of level, uniform, light loam, with a very leachy subsoil,
at the station's temporary experimental farm leased of Mr. Webb
at Centerville. This land had not been cultivated or fertilized
for some years before our experiments began, and so was in
very poor shape for growing crops of any kind. Amount of
yield, however, except in a comparative way, was not contem-
plated in these experiments.
*
740 CONNECTICUT EXPERIMENT STATION REPORT, I909-I9IO.
The land was divided into plots as follows : The east half
each year was fertilized with manure at the rate of sixteen to
eighteen tons per acre, while the west half received about the
equivalent of the nitrogen in the manure in the shape of two ap-
pHcations of nitrate of soda (rate of 450 lbs. per acre) . Each half
received the same amount of muriate of potash (rate of 300 lbs.
the first and second years, and 450 lbs. the other two years, per
acre) and bone meal (rate of 200 lbs. per acre each year).
As the manure had also some phosphorus and potash in it, this
naturally gave that half of the field a somewhat better fertili-
zation than the half on which sodium nitrate was used, and as
a matter of fact it showed this each year in a more luxuriant
growth and a larger yield.
Running crosswise of the manured and sodium nitrate halves,
the field was divided into halves, one of which received level
culture and the other modified ridge culture. This ridged half
was really cultivated the same as the level until the first to the
middle of July, when, during the last two cultivations, the
potatoes were ridged by the shovel cultivators as much as
possible, and in some seasons hilled further with a hoe. In
order to bring the tubers in the level culture near the ground
and those in the ridged culture as deep as possible, the former
were planted only three or four inches deep, while the latter
were planted five to seven inches. Ordinary cultivation, not
averaging once a week, was given the whole field. Some hand
work with the hoe was also given. Each year the halves given
level and ridged culture were reversed, so that any inequality
of land might be cancelled.
The central halves of the ridged and level cultivated rows
were sprayed with Bordeaux mixture (4-4-50 formula), leaving
similar unsprayed rows on either side. Usually about three
sprayings with Bordeaux were given, and as these were made
by hand, they were very thorough. The first spraying was
generally given about the middle of July, and the last about
the first of September. All the potatoes were sprayed for insects,
either with Paris green or with arsenate of lead, so as to make
conditions the same so far as insect injury was concerned.
These treatments divided the field into eight equal areas, each
receiving some diflFerent point of treatment, as follows : ( i )
sprayed, manured, ridged; (2) unsprayed, manured, ridged;
SPRAYING POTATOES IN DRY SEASONS. 74^
(3) sprayed, sodium nitrate, ridged; (4) unsprayed, sodium
nitrate, ridged; (5) sprayed, manured, level; (6) unsprayed,
manured, level; (7) sprayed, sodium nitrate, level; (8)
unsprayed, sodium nitrate, level.
The potatoes were dug in October, after all the vines were
dead, and comparative yields determined by taking the counts
and weights from fifty-foot lengths in two separate rows of each
plot for comparison, but the figures given in the tables are for the
combined one hundred feet. To avoid any unevenness due to the
difference in the land, the sprayed and unsprayed rows, which
otherwise received the same treatment, were always taken as near
together as possible.
Results. Sprayed versus Unsprayed. In the four years, out
of the forty-four comparisons of fifty feet of sprayed vines with
the corresponding unsprayed vines, the sprayed lots in every case
except three gave a greater yield. In these three exceptions the
average of the two tests of fifty feet of sprayed vines in each
case was greater than the corresponding average of the two fifty
feet of unsprayed vines, so that it can be stated that during the
four years' tests the sprayed lots invariably gave a higher yield
than the unsprayed. Table i gives the averages for the four
years of these sprayed and unsprayed potatoes, and from this we
find that the average increase of all the sprayed vines over un-
sprayed vines was about 32 per cent. The increased yield of the
sprayed over the unsprayed by years was as follows : In 1906,
30 per cent. ; in 1907, 24 per cent. ; in 1908, 17 per cent. ; in 1909,
53 per cent. Plate XXXVII b shows the comparative yields in 1906
on the sodium nitrate half (i) sprayed, ridged; (2) unsprayed,
ridged; (3) sprayed, level; (4) unsprayed, level. As shown in
our previous experiments, the increased yield of the potatoes was
not only due to increased numbers of marketable tubers, but also
to increased weight of the tubers, especially the larger ones.
In every one of these years, the spraying, theoretically, more
than paid for itself, despite the fact that none were blight years.
Stewart, in the 1906 Report of the Geneva, N. Y., Experiment
Station, shows that out of fourteen cooperative experiments with
farmers in different parts of the state in 1905, it cost from $2.44
to $6.84 per acre to make the sprayings, or an average cost for
all of $4.25 per acre. We think that in this state, to be on the
safe side, we may estimate the cost, including bother, of spraying
742 CONNECTICUT EXPERIMENT STATION REPORT, I909-I9IO.
at $10.00 per acre. It often requires more time to cart water and
make up the mixture than it does to apply it. If the spraying is
done by hand, it also costs more than when done with spraying
machines, but a more thorough job can be done in this way with
three sprayings than with five by any power sprayer we
have seen. Taking the cost of spraying then, at $10.00 per acre,
and the average yield of an unsprayed field in this state at the
conservative figure of 130 bushels per acre, we find that the low-
est increase in yield due to spraying, namely, 17 per cent., means
22 bushels, and the highest increase, 53 per cent., means 69
bushels. At the very low price of fifty cents per bushel, the
lowest increase would mean $11.00, or one dollar net profit, and
the highest, $34.50, or $24.50 profit. We have made these esti-
mates especially conservative by taking comparatively low yields
and a high cost of spraying per acre. Years when blight really
did harm in the fields would of course make the gains very consid-
erably greater, if the spraying were well done. '
The question naturally comes up, why did the sprayed potatoes
give this increased yield over the unsprayed if there was no par-
ticular injury caused by the late blight fungus? Some little
benefit was no doubt derived from the prevention of the early
blight, but this must have been scarcely appreciable because this
fungus was not at all conspicuous these years. Again, some very
small benefit may have been due to lessening insect attack, since
potatoes sprayed with both Bordeaux and Paris green keep off
the insects somewhat better than where sprayed only with Paris
green. This is especially true as regards the potato flea beetle.
But here again the gain was of a very minor kind. Ordinarily
botanists have explained this increase as due to some stimulative
effect the Bordeaux mixture has on the chlorophyll of the potato
leaves in increasing starch production. Personally, the writer
believes that the results are largely due to conservation of mois-
ture in the leaves in dry seasons by clogging up the stomata and
zvater pores with the sediment of the spray. The reasons for this
belief are (i) that the potato leaves, through their numerous
stomata and terminal water pores, lose water very easily, and are
especially susceptible to what is known as tip burn in dry seasons ;
(2) that the unsprayed vines uniformly suffered earlier and more
severely from tip burn than the sprayed, which were green for
about two weeks after the unsprayed were dead; (3) that in
SPRAYING POTATOES IN DRY SEASONS. 743
1 910, which was a season Hke the preceding years, except with a
little injury from blight at the very end of the season, spraying
with "Sulphocide" and commercial lime-sulphur, sprays with
comparatively little sediment, did not prolong the Hfe of the
vines or give increased yield, while spraying with Bordeaux
mixture did.
Results: Ridged versus Level Culture. As to the primary
object of these two methods of culture, we have very little data,
since there was practically no rot in the potatoes during the four
years. We hope to continue the experiment until seasons favor-
able for rot shall give us data on this subject. That there is some
basis for the belief that ridging will be of help in lessening the
rot was shown in our experiments in 1910 in another field, where
the ridged rows, both sprayed and unsprayed, gave practically no
rot against a small per cent, in the level rows. This was espe-
cially true of the unsprayed level rows, which gave about nine
per cent, of tubers rotted against only one-half per cent, in the
sprayed level rows, though the blight appeared on the foliage only
in a small way toward the end of the season.
While our data are not very enlightening on this point, still the
experiments do show results along a related line, namely, that the
ridging did not materially lessen the yield. There are those in
this state who advocate level culture because of the supposed
increased yield over ridging, and if this is so, then any increased
yield due to prevention of rot in the ridged potatoes might be
more than outbalanced by the increased yield due to level culture,
especially taking the yields year after year, many of which show
no rot. However, with our modified ridged culture (as explained
previously) we do not find in averaging the four years that the
ridged potatoes gave any very materially smaller crop than the
level, since the average of the latter was only about 6 per cent,
higher than the former, and to offset this, the 19 10 crop in a
different field slightly favored the ridged. Taking the yields by
years, the level culture gave slightly better crops in 1906, 1907,
and 1908, and the ridged in 1909 and 1910. As these last four
years were chiefly drought years, the test was even more severe
than it v/ould be in wet seasons. Likewise, the data that we
obtained in some cooperative experiments with farmers in 1906
did not seem to show that the ridged potatoes were at a disad-
vantage, judging from the yields given and the general opinion
of the growers where no measurements were taken.
52
744 CONNECTICUT EXPERIMENT STATION REPORT, I909-I9IO.
In connection with the spraying, it may be noted that the
averdge for the four years gave a slightly greater proportional
increase in the sprayed ridged over the unsprayed ridged than
was given by the sprayed level over the unsprayed level, on both
the manured and the sodium nitrate plots, though in two of these
years (1907 and 1909) the proportional increase was greater for
the level. This perhaps may be explained by the unsprayed
ridged potatoes suffering on the whole slightly more from the
droughts.
Results: Manure versus Sodium Nitrate. Here again we did
not get any data relative to whether or not manure increased
the amount of rot in fields in blight seasons. From our corre-
spondence with farmers, they seemed to favor the opinion that
manured fields rot worse than those where chemical fertilizers
«
only are used. While we did not get data on the blight, we did
obtain data regarding scab and the use of manure, which we will
mention later.
Of course the manured half of the field each year gave a greater
yield than the sodium nitrate half, since it was better fertilized.
The average increase for the four years of the manured over the
sodium nitrate was about 47 per cent. There is no doubt that
manure is a very good fertilizer for potatoes, but at the same time
there is greater danger of injury from scab and apparently from
rot with its use. The most sensible way to use manure seems to
be either in a heavy application on corn the previous year, using
only a commercial fertilizer the same year with the potatoes, or
at least to put it on the land and plow it in the preceding fall rather
than in the spring just before planting the potatoes, as was done
in our experiments. As regards spraying, the sodium nitrate
sprayed rows uniformly gave a higher per cent, of increase over
the checks, either ridged or level, than did the sprayed manure
roAvs over the unsprayed checks. We are not sure of the reason
for this, unless it was because the manured rows suffered earlier
and more severely from the drought. Our manured plot also had
more weeds than the sodium nitrate plot.
Results: Scab. These experiments showed very strikingly how
the continued use of the same land for potatoes greatly increases
the amount of scab. Even if it were of no benefit in the prevention
of rot, rotation certainly is of value in lessening scab. The first
year the potatoes were on the land the per cent, of scab v/as so
SPRAYING POTATOES IN DRY SEASONS.
745
small that it was not determined. It certainly was below 5 per
cent., and probably not over i per cent. The second year, 1907,
the scabby tubers had increased to 22 per cent., in 1908 to 47 per
cent, (the same potatoes in our general rotation fields this year
gave only about i per cent, scabby), and in 1909 to 63 per cent.
The last two years the scab was so bad as to seriously affect the
market value of the potatoes. The scab on the manured half
was more serious than on the sodium nitrate half, since the
average scab for the three years 1907 to 1909 for the former was
48 per cent., while on the latter it was only 33 per cent. As
regards level and ridged rows, there was more scab in 1907 and
Table I. — Spraying Experiments — Average, 1906, 1907, 1908 and 1909.
(i) Spraj'ed, Manured, Ridged
(2) Unsprayed, Manured, Ridged ..
(3) Sprayed, Sod. Nitrate, Ridged ._
(4) Unsprayed, Sod. Nitrate, Ridged
(5) Sprayed, Manured, Level _
(6) Unsprayed, Manured, Level
(7) Sprayed, Sod. Nitrate, Level
(8) Unsprayed, Sod. Nitrate, Level .
Average — Spra3'ed
Average — Unsprayed
Very large
Large to
meaium
Medium to
small
Total
marketable
Very
No.
Wt.
2
No.
Wt.
No.
Wt.
No.
Wt
No.
2
77
25
161
25
240
52
82
0
0
61
19
141
21
202
39
74
3
2J/2
64
20
102
14
170
3b
40
0
0
50
14
90
12
140
25
45
2
i^
7B
2.S
1^3
27
264
54
119
I
I
68
18
168
22
236
43
151
0
0
66
20
131
17
iq7
3«
74
0
0
4.'5
13
116
15
162
28
80
I
I
71
23
144
21
217
45
77
0
0
5&
16
68
17
185
34
87
1909 in the ridged rows and less in 1908, and in the average for
the three years the ridged ran slightly higher, though whether this
means anything or not we do not know. As the level and ridged
halves were alternated each year, this shows that it was the same
side of the land that each time gave the most scab, and so the
nature of the land rather than the manner of cultivation may have
been the determining factor. It is certain, however, that the
level rows suffered much more from sun scald.
Details of Experiments in igo6.
Treatment. May' 2: Planted with Carmen No. 3. June 21:
Sprayed all with Paris green. July 6: Gave second spraying with
Paris green. July 16: Gave first spraying with Bordeaux mixture
(4-4-50) by hand. Used Paris green in Bordeaux, and gave un-
746 CONNECTICUT EXPERIMENT STATION REPORT, I909-I9IO.
sprayed half the third treatment with Paris green, as bugs were
unusually bad. Also gave first ridging to ridged half about this
time. July 24: Gave final ridging. July 2'/: Made second treat-
ment with Bordeaux. August 8: No blight, but a little early
blight and considerable tip burn, especially on unsprayed vines.
Augiist 11: Gave third spraying with Bordeaux. Found a very
few blight leaves on unsprayed vines. August 26: Difference
between sprayed and unsprayed vines quite marked in favor of
former, due to tip burn and insect injury. September 6: Un-
sprayed vines fully two-thirds dead from tip burn, while on the
sprayed not one-half the leaves were dead. Gave two rows only
Table II. — Spraying Experiments in 1906.
(i) Sprayed (3), Manured, Ridged...
(2) Unsprayed, Manured, Ridged
(3) Sprayed (4), Sod. Nitrate, Ridged
(4) Sprayed (3), Sod. Nitrate, Ridged
(5) Unsprayed, Sod. Nitrate, Ridged
(6) Sprayed (3), Manured, Level
(7) Unsprayed, Manured, Level
(8) Sprayed (4), Sod. Nitrate, Level.
(9) Sprayed (3), Sod. Nitrate, Level.
(10) Unsprayed, Sod. Nitrate, Level
Average — Sprayed (3)
Average — Unsprayed
Very large
Larj
med
'e to
ium
Medi
sm
um to
all
Total
marketable
Very
small
No.
Wt.
No.
Wt.
No.
Wt.
No.
Wt.
No.
Wt.
5
33/
154
43
159
l^Vz
318
65^
28
%
0
0
125
32U
140
H%
265
4i>y2
22
%
2
i^
167
45U
106
12^
273
sg'A
15
1/5
5
SVz
122
32 3^
134
143^
261
51
16
Vs
0
0
103
25
109
loi/.
212
35 'A
22
%
8
5
171
51
166
19?^
345
ISVz
35
y.
.3
2^3
140
27 'A
201
20 3^
344
boU
29
K
2
I'A
159
41
15a
iby2
31S
59
24
u
0
0
146
42 J^
143
ibVz
289
583^
21
%
0
0
102
29^
164
nU
266
47
26
H
3
3
148
42
150
17
303
bi
25
'A
I
r
117
28
153
16
272
47
25
yi
Rot
No.
2
14
5
I
r
o
4
2
o
5
I
6
a fourth treatment, as vines were too far gone and blight was
doing no particular harm.
Results: It is a question whether the fourth treatment did much
good, though in the ridged rows it gave a better yield than the
ridged row sprayed only three times. There was more rot this
year than any other, yet not enough to do any harm. Besides
the evident difference in the life of the vines, the yield also showed
a corresponding difference in favor of the sprayed rows. The
sprayed (3) manured ridged lot gave a 40 per cent, increased
yield over the unsprayed manured ridged, as compared with 24
per cent, increase for the sprayed manured level over their un-
sprayed rows ; the sprayed sodium nitrate ridged gave 43 per cent,
increase over the unsprayed sodium nitrate ridged, while the
sprayed sodium nitrate level gave 25 per cent, increase over the
SPRAYING POTATOES IN DRY SEASONS.
747
unsprayed check rows. The average of all the sprayed rows
over the unsprayed was about 30 per cent., or the second best
results of the four years' test. The details of yields are given in
Table II.
Details of Experiments in ipoy.
Treatment. On May i planted Green Mountain variety. July
j; Gave first application to all rows of insecticide, as bugs were
late in starting this year. July 8: Gave first ridging to ridged
half. July 16: Gave first spraying with Bordeaux, and used
Table III. — Spraying Experiments in 1907.
Treatment (
(i) Sprayed (3), Manured, Ridged
(2) Spraj^ed(2), Manured, Ridged
(3) Unsprayed, Manured, Ridged
(4) Sprayed (3), Sod. Nitrate,
Ridged
(s) Sprayed (2), Sod. Nitrate,
Ridged .-.
(6) Unspra3'ed, Sod. Nitrate,
Ridged
(7) Sprayed (3), Manured, Level.
(8) Sprayed (2), Manured, Level.
(9) Unsprayed, Manured, Level.
(10) Sprayed (3), Sod. Nitrate,
Level
(11) Sprayed (2), Sod. Nitrate,
Level
(12) Unsprayed, Sod. Nitrate,
Level .
Average — Sprayed (3)
Average — Unsprayed
Very large
Large to
medium
Medium to
small
Total
marketable
Very small
Rot
No.
Wt.
No.
Wt.
No.
Wt.
No.
Wt.
No.
Wt.
0
0
0
0
0
0
19
20
21
7
143
140
112
21^
21%
17
162
160
133
28K
29
23^
164
130
97
6^
5%
4X
0
0
0
0
0
24
7
93
12^
117
19;^
87
2%
0
0
0
33
10
96
I3K
129
23%
68
2%
0
0
0
0
0
0
0
0
0
19
13
22
9
3'A
92
162
155
127
r2>^
25K
25X
III
175
177
136
18
91
162
130
262
4X
10
0
0
0
0
0
0
28
m
117
14
145
22^
122
3%
0
0
0
10
3U
118
18^
128
22X
148
S%
0
0
0
0
0
0
0
7
21
14
2X
7
5
102
128
108
I5K
19
16
109
149
122
1714:
26
21
149
128
150
6X
5
6
0
0
0
Scab
Per
Cent.
34
41
32
10
16
35
19
16
18
14
16
20
25
insecticide with it and alone on unsprayed vines. July ip: Gave
final ridging and cultivation of potatoes. August 3: Made second
spraying with Bordeaux. No signs of blight, but tip bum bad,
especially on unsprayed potatoes, and showed more with those on
manured rows than on sodium nitrate rows. September 6: Gave
third spraying to six rows only (three ridged and three level),
as it was rather late to do much good. No signs of blight this
season. Unsprayed vines with level culture more uniformly dead
than the unsprayed ridged. Sprayed rows still showing consider-
748 CONNECTICUT EXPERIMENT STATION REPORT, I909-I9IO.
able percentage of green leaves, especially on sodium nitrate part,
but difference not so marked as in previous year.
Results. On account of drought, the yield this year was con-
siderably less than any of the other years. The third spraying
was too late to do any good at all. If the first spraying had been
made about the first of July and the third the last of August, the
results would have been better. The sprayed (3) manured ridged
rows gave an increase of 20 per cent, over the unsprayed manured
ridged portion, while this was increased to 27 per cent, on the
sprayed manured level over the corresponding unsprayed portion.
The sprayed (3) sodium nitrate ridged rows gave only 8 per cent,
increase (30 per cent, in the case of those sprayed twice) over
the unsprayed, while the sprayed (3) sodium nitrate level gave 28
per cent, over the unsprayed portion. The average increase of
all the sprayed over the unsprayed was 24 per cent. Table III
shows details of yields.
Details of Experiments in ipo8.
Treatment. On April 2p, planted Green Mountain variety.
July 5 to 10: Gave first ridging. Vines were sprayed twice with
arsenate of lead for bugs, which were not bad this year. July
I/: Gave first spraying with Bordeaux. This was rather late, as
the tip burn was already evident, especially on manured half.
July 2/: Gave second spraying with Bordeaux. Sodium nitrate
half with less tip burn than the manured half, and sprayed vines
somewhat better than unsprayed. August ij: Gave third spray-
ing with Bordeaux. Very little early, and no late blight. Sprayed
rows somewhat better than unsprayed. September 11: Vines
nearly all dead except a few scattered ones. Sprayed vines
showed less difference over unsprayed this year than any other,
due no doubt to the fact that drought was bad and the first spray-
ing was not given until tip burn began to show its effects^on the
vines. No blight at all.
Results: The spraying this year gave the least results of any
year, showing only an average increase of 17 per cent, over the
unsprayed. Had the first spraying been made earHer, there would
no doubt have been less injury from tip burn, with a consequent
increase in yield. As the drought affected the manured rows
most, the increased yield due to spraying was least in these. The
sprayed manured ridged gave 12 per cent, increase over the
SPRAYING POTATOES IN DRY SEASONS.
7 49
unsprayed, while the sprayed manured level gave only 5 per cent,
increase over the unsprayed part. On the other hand, the sprayed
sodium nitrate ridged gave 46 per cent, increase over the un-
sprayed rows, while the sprayed sodium nitrate level gave 20 per
cent, increase over the unsprayed portion. See Table IV.
Table IV. — Spraying Experiments in 190S.
(i) Sprayed (3), Manured, Ridged
(2) Unsprayed, Manured, Ridged
(3) Sprayed (3), Sod. Nitrate,
Ridged
(4) Unsprayed, Sod. Nitrate,
Ridged
(5) Sprayed (3), Manured, Level
(6) Unsprayed, Manured, Level.
(7) Sprayed (3), Sod. Nitrate,
Level
(8) Unsprayed, Sod. Nitrate,
Level
Average — Sprayed
Average — Unsprayed .-
Very large
Large to
medium
No. Wt
71
56
61
44
6g
77
40
43
60
55
20^
24 >^
24
12%
21
17
Medium to
small
128
126
75
67
163
158
92
122
III
20>^
20X
CO
23^
21^4
I7X
I2>^
18
16
■ Total
marketable
200
182
137
III
232
235
160
135
182
166
45X
40K
34
23X
48
451^
243/
39
33
Very small
55
103
39
108
174
76
56
68
93
2%
3H
3%
5^
2^4
2
3
Rot
No.
Scab
Per
Cent.
46
29
23
71
58
51
43
52
43
Details of Experiments in ipop.
Treatment. Used Green Mountain variety this year, not plant-
ing until May 11, as the season was late. Gave all a couple of
sprayings with arsenate of lead for bugs on June 24 and July 7.
About the middle of July gave first ridging, and the final one on
July 27, when first treatment with Bordeaux was also made.
August p: Made second spraying with Bordeaux. September 2:
Gave third spraying with Bordeaux. Sprayed rov/s now much
greener than unsprayed, especially those ridged, as the vines in
the unsprayed ridged rows were all dead from tip burn. Sep-
tember 28: Vines all dead except one here and there. No late
blight, and very little early blight. Practically all of premature
dying due to tip burn.
Results. The spraying this year gave the best results of any
of the four, since the average increased yield was 53 per cent.
The yields this year were better than any other year except 1906.
The sprayed manured ridged gave an increase of 45 per cent, over
75° CONNECTICUT EXPERIMENT STATION REPORT, I9O9-I9IO.
the unsprayed manured ridged, while the sprayed manured level
gave 48 per cent, over the unsprayed check. On the other hand,
the sprayed sodium nitrate ridged gave 60 per cent., and the
sprayed sodium nitrate level 79 per cent, over their unsprayed
checks, the last being the greatest increased yield due to spraying
obtained in any of the experiments during the four years. See
Table V.
Table V. — Spraying Experiments in 1909.
(i) Sprayed (3), Manured, Ridged
(2) Unsprayed, Manured, Ridged
(3) Sprayed (3), Sod. Nitrate,
Ridged
(4) Unsprayed, Sod. Nitrate,
Ridged
(5) Sprayed (3), Manured, Level
(6) Unsprayed, Manured, Level
(7) Sprayed (3), Sod. Nitrate
Level
(8) Unsprayed, Sod. Nitrate
Level
Average — Sprayed
Average— Unsprayed
Very
large
Largre to
Medium to
small
Total
marketable
Very
small
Rot
No.
Wt.
No.
Wt.
No.
Wt.
No.
Wt.
No.
Wt.
4
VA
64
24'/^
212
39>^
280
67>^
79
■h)i
0
0
0
44
15
185
31/2
229
4(3/2
73
2%
0
5
^%
50
18
108
17K
163
40
28
IX
0
0
0
^4
11'/^
qi
I3J4
125
25
28
IJ4:
0
0
0
61
22
242
39 K3
303
61/2
173
5K2
I
0
°
46
16
184
25K
230
41/2
139
i%
0
0
0
51
i8>^
145
21
196
39K
78
2X
0
0
0
2q
q
108
13
137
22
89
^y^
0
2
2
.S6
21
177
2Q
235
52
89
3
0
0
0
38
13
142
21
180
34
82
3
0
Scab
Per
Cent.
77
66
67
60
65
42
62
64
Recommendations.
(i) Seed. The blight fungus carries over in the tubers, and
the infected ones may be recognized in the spring by the slightly
sunken, often pitted, reddish-brown, superficial dry rot. While
the use of such tubers is not advisable, still blight may do much
harm in a field in which the seed tubers were perfectly free from
the fungus. As to varieties, we know of no good standard variety
grown in this state that is not subject to blight of the vines and
rot of the tubers, though there may be more variation in the latter
respect than in the former. Such varieties as have been found by
experiment to possess more or less resistance to either blight of the
foliage or rot of the tubers seem to have it at the expense of
quaHty of tubers. However, this is a subject for further investiga-
tion, and probably offers greater possibilities than have yet been
developed.
SPRAYING POTATOES IN DRY SEASONS. 75 ^
(2) Planting. For early varieties early planting, in order to
mature them as soon as possible to escape injury by blight or
drought in midsummer, is no doubt advisable. But for late
varieties we rather favor only medium early planting, say the last
of April to the first week of May, because if planted too early,
late potatoes suffer more in the years of drought than if planted
later, since they are usually so far matured that a dry July or
August will kill them, while the later planted fields, especially if
sprayed, will manage to pull through until the moist fall season,
and so really have a longer period of growth. We recommend
that the seed be planted fairly deep, five to seven inches, to
develop the tubers in the ground as deeply as possible as a protec-
tion against rot and sun scald.
(3) Rotation. We advise rotation, having potatoes on a dif-
ferent piece of land each year. A four years' rotation, such as
the following, is not bad for this state: (i) Corn. (2) Potatoes.
(3) Rye. (4) Leguminous crop (sow in fall with the rye, or the
following spring). Growing potatoes on the same land two or
more years in succession increases scab and possibly in favorable
seasons an earlier appearance of blight and greater rot, though so
far as the blight is concerned this is largely conjecture.
(4) Fertilisation. Manure plowed into the land in spring just
before planting the potatoes increases the amount of scab and
possibly the amount of rot in blight seasons. If a heavy coat of
manure was used with the com the previous year, commercial
fertihzers only may be used with the potatoes. Or if manure is
used, plow it in the preceding fall. Horse manure is probably
the least objectionable. The following home-mixed fertilizer (per
acre), recommended by Dr. Jenkins, seems to merit extended use
in this state: Nitrate of soda, 150 lbs.; muriate of potash, 200
lbs. ; acid phosphate, 400 lbs. ; tankage, 350 lbs.
(5) Cultivation. We recommend a thorough cultivation, to
conserve the moisture, in the nature of a combined level-ridge
culture. That is, give the vines thorough level culture up to the
last two cultivations, and then begin sometime early in July to
ridge up the rows with the shovel cultivators, moderately at first,
and as much as possible the second time. After both of these
ridgings, mulch up the soil between the ridges by shallow cultiva-
tion as much as possible without pulling down the ridges, so as to
hold in the moisture. This ridging, we think, protects the tubers
752 CONNECTICUT EXPERIMENT STATION REPORT, I909-I9IO.
more against rot, by burying them deeper under the soil, so that
the blight spores are not washed down to them so easily. It also
gives better ventilation to the vines, by allowing water on the
foliage to dry off quicker, and by holding the vines erect and off
the ground makes spraying easier and more effective.
(6) Spraying. As year after year, wet or dry, we have got
increased yields due to spraying potatoes with Bordeaux mixture
(4-4-50), we recommend the spraying as a yearly feature in
growing late potatoes in this state. The spraying should be done
thoroughly, whether by hand or by power, which means that it
will take from two to three barrels of the mixture per acre. With
the ordinary horse-power sprayers using fixed nozzles, it is
necessary to go over the rows twice, in opposite directions, at each
spraying, in order to properly coat the vines. The first spraying
should be given about the first of July, and if desired, an insecti-
cide, either Paris green, rate of Yz lb., or arsenate of lead, rate of
3 lbs., to 50 gallons of Bordeaux, may be added. AVe do not
believe from our trials with various other sprays that there is
anything as good for potatoes as the home-made liquid Bordeaux
mixture.
For the late blight alone, the middle of July is early enough for
the first spraying, but we advise the first of July, since better
results against tip burn and early blight may be expected, and
then, too, by the middle of July it is more difficult to reach the
lower parts of the vines when a luxuriant growth has been made.
The number of times of spraying will depend upon the weather
and the manner of spraying. When it is done with leads of hose
by men on the ground, only three or four sprayings are necessary.
When stationary nozzles attached to the back of the wagon are
used, whether the power is furnished by hand or by horse, it will
take from four to seven sprayings, depending on the weather, to
do good work. In any case it is essential that the vines be kept
covered with spray up to the time of their death, otherwise the
blight may develop slowly on the green foliage in the fall, and
while doing no harm in preventing tuber formation, may work
great havoc by rotting the tubers already formed by the spores
washing down on them. See Plate XXXVII a.
OOSPORES OF POTATO BLIGHT. 753
III. OOSPORES OF POTATO BLIGHT, Phytophthora
infestans.
Importance. Very few fungi have caused the serious and
widespread injury that in certain seasons has been wrought by
the potato bhght. So great was this damage in Europe about
1845, that three governments appointed commissions to investi-
gate the trouble and determine surely the cause, as there was
considerable difference of opinion on this latter point. In North
America the blight was very destructive at the same time.
Thoreau, in his book "The Maine Woods," written about 1846,
says : "The potato rot had found him out here, too, the previous
year, and got half or two-thirds of his crop, though the seed was
of his own raising." A similar condition existed in Canada, as
shown by a letter written in 1844 to Dr. Bellingham of Dublin
(see Berkeley in Journ. Hort. Soc. London i : 11. 1846), which
reads as follows :
During the months of July and August we had repeated and heavy
showers, with oppressive heat and an atmosphere strongly charged with
electricity. Toward the close of the month of August I observed the
leaves to be marked with black spots, as if ink had been sprinkled over
them. They began to wither, emitting a peculiar offensive odor; and
before a fortnight the field, which had been singularly luxuriant and
almost rank, became arid and dried up, as if by a severe frost. I had the
potatoes dug out during the month of September, when about two-thirds
were either positively rotten, partially decayed and swarming with worms,
or spotted with brownish colored patches, resembling flesh that had been
frost-bitten. These parts were soft to the touch, and upon the decayed
potatoes I observed a whitish substance like mould.
Concerning the condition at this time in Europe, Berkeley, in
the article mentioned above, writes : "Few subjects have attracted
more attention, or have been more variously canvassed than the
malady with which potatoes have been almost universally visited
during the autumn of 1845." Since that great outbreak, which
resulted in famine in Ireland, the blight has been frequently
reported in the potato districts of the cooler temperate regions,
but only under special conditions of moisture, such as rainy or
foggy weather of some duration in July and August, has it
developed in epidemics of widespread and unusual importance.
754 CONNECTICUT EXPERIMENT STATION REPORT, I9O9-I9IO.
When the writer first came to this station in 1902, the potato
blight was at the height of one of its periods of destructiveness.
In that year the injury resulted largely from the very premature
killing of the vines, some fields going down in a week during
the latter part of July. In 1903 the vines were killed somewhat
prematurely, and there was serious rotting of the tubers. This
tuber rot was even more serious in 1904, being in fact more
destructive in this respect than in any other of the ten years
in which we have gathered data. Correspondence at the time
with farmers over the state brought out the following items :
J. B. Gelston, East Haddam, — "almost a total failure" ; Vine
Hill Farm, Elmwood, — "lost about sixty per cent, of crop" ; W. S,
Thomas, Groton, — "saved about one-third of crop" ; W. S. Lee,
Hanover, — "I probably lost three-fourths of my crop" ; W. M.
Shepardson, Middlebury, — "about one-half crop rotted" ; E.
Healey, Mystic, — "I think three-fourths rotted before they were
dug" ; C. M. Ladd, North Franklin, — "estimated two-thirds crop
rotted." Since that year there has been comparatively little injury
in the state from blight, especially during the dry years from
1907 to 1909. In 1910 some little rot started, but the vines
were too far gone from tip burn before the appearance of the
blight for it to get a good start.
With the reappearance of a season having a wet or muggy
July and August, we may expect further outbreaks of this trouble.
The work of this and other stations, however, has shown that
much of the injury may be prevented by spraying and other
protective measures, and that an increased yield even may be
expected by spraying in seasons with practically no blight. (See
preceding article, also our Report for 1904, p. 363.) This part
of our object in studying potato blight has been largely accom-
plished.
Historical Interest. Another feature of potato blight that is
of especial interest is its historical importance from a botanical
standpoint. Some idea of the early study made of it is well
illustrated by the following extract, published in 1846 in The
Amer. Journ. Sci. and Arts, vol. 2, page 281, and written by J. P.
Norton :
Little has as yet been done on any organized plan in this country
(United States). In Europe the case has been very different. In Holland
and Belgium a committee was first appointed to collect facts calculated to
OOSPORES OF POTATO BLIGHT. 755
throw light on the nature of the disease. In one of the Dutch provinces,
Groningen, a separate commission was appointed for the same purpose.
In Germany, Liebig, among others, has turned his attention to the potato,
and has lately published some observations on its nitrogenous constituents.
A number of the French philosophers, both alone, and under the auspices
of the Central Society of Agriculture, have also attended to the subject.
M. Payen has lately published three or four reports containing the results
of elaborate microscopic and chemical researches. The English govern-
ment sent a commission to Ireland of three distinguished scientific men,
with directions to obtain as much information as possible on the nature
and extent of the disease. In Scotland originated the most extended
schemes of all. The subject was taken up in its several branches, as it is
connected with botany, meteorology, entomology, and chemistry. Each
branch was referred to a competent person, and the investigation is still
in progress.
Object of Investigation. Many investigators since have made
careful studies of the life history of this fungus. Considerable
interest was excited by the Smith-De Bary controversy concern-
ing its disputed winter spore stage, known as oospores. It is
upon this point that the writer has become especially interested
by reason of several years' study of the fungus in artificial cul-
tures. Our object was to secure these oospores in cultures
through the use of special strains of the fungus or by particularly
favorable cultural media, since in our first cultures no indication
of their existence was revealed. In. this respect we have finally
been successful, though their abundant production has not yet
been accomplished. We have made a special study of cultural
media, environmental conditions, etc., in the hope that some light
might also be thrown on the related question why certain stages
of a fungus, usually the«conidial ones, are grown readily in arti-
ficial cultures, while other stages, usually the mature one, rarely
if ever appear, though not uncommon in nature. We cannot
say that we have yet accomplished much in this direction, though,
it often takes tedious preliminary work of seemingly little impor-
tance to lead up to the final successful results.
Previous Work by Others. We have referred to the Smith-
De Bary controversy, carried on in the seventies over the so-
called oospores of potato bhght. The former claimed to have
found these sexual spores in old leaves and tubers injured by
the blight fungus. The latter, a more careful investigator, failed
to find any oospores of this nature that he could connect with
the blight fungus, and he threw so much doubt on the conclu-
756 CONNECTICUT EXPERIMENT STATION REPORT, I909-I9IO.
sions of Smith that botanists generally have regarded that the
existence of these oospores has not been proven. Since that time
other investigators have claimed, on a few occasions, to have found
bodies like immature oospores. The writer has found various
suspicious bodies in the leaves and tubers of infected plants,
but has never been convinced of their real nature. Some of
these bodies are much like oospores in appearance, but in our
experience they have never been so abundant or typical as to
convince us of their connection with the blight fungus. Plate
XXXIX G-I shows some of these bodies which are easily dis-
tinguished from the true potato oospores shown above.
Two French investigators, Matruchot and Molliard, were
apparently the first to grow the blight fungus in artificial cultures.
Their reports were made in 1900 and 1903. They were not suc-
cessful in gaining any Hght concerning the oospores from their
cultures.
In 1904 the writer first made artificial cultures of the bhght
fungus, and about this time Jones and his assistants at the Uni-
versity of Vermont took up the study of the fungus in the same
manner. The results of their work have not been published
in detail, though the main points have been presented in two
papers before our botanical societies, and brief abstracts of these
have appeared in Science. In their work, so far as published,
they have had more success than the writer, up to the present
investigation, in obtaining curious, immature, and apparently
somewhat abnormal bodies, apparently of an oogonial nature, but
whose exact identity was left in doubt, since there were no signs
of antheridia or of oospores. The writer previously has been
inclined to call these bodies chlamydospores. From the results
of our present investigations we believe that they are essentially
abnormally and imperfectly developed oogonia (possibly function-
ing as chlamydospores) due to lack of fertilization by normal
antheridia.
Previous Work by the Writer. The results of our previous
work with the blight fungus in artificial cultures have been pre-
sented in the Reports of this station for 1905 (p. 304) and 1908
(p. 891). In these investigations, while we occasionally obtained
swollen and differentiated threads in the cultures, we were
unable to produce these at will, or to further their development,
so their nature was largely a matter of speculation. Jones and
OOSPORES OF POTATO BLIGHT. 757
his assistants in the meantime had been much more successful
with the development of these bodies, but with culture media
much less suited to the vigorous development of the fungus.
Our efforts, however, were rewarded at the time by learning
how to best obtain cultures of the fungus, and what media were
best suited to its luxuriant development. In this respect we
believe our cultures have proven better than any of those yet
attempted. The Lima bean juice agar described in our Report
for 1908 was up to that time the most satisfactory of these media.
It has been by continued efforts to develop a specially favorable
medium that, for the greater part, we have finally accomplished
the desired results.
Present Investigations.
Nature of Work. We shall give in the following pages the
general results of our recent endeavors to produce the oospores
of Phytophthora infestans in artificial cultures. A short prelim-
inary account of this work has recently appeared in Science,
vol. XXXIII, p. 744. We wish here to acknowledge indebtedness
to our assistant, Mr. E. M. Stoddard, who has made most of these
cultures under our direction, and has been very helpful in deter-
mining the results thus obtained, since it has required hundreds
of cultures, and the examination of these several times, to obtain
the required data. The main lines of procedure have been to
secure favorable strains of the fungus for the work, and to
induce these strains to produce oospores by means of favorable
media or special environment. We shall discuss these points in
detail in the following paragraphs.
Strains. The cultures used in our previous work were lost or
allowed to die out from time to time, so that these reported here
are from different sources, except the one from Holland. These
strains, besides representing a variation in origin, also present
different lengths of time of growth in artificial cultures. For
example, we have continuously grown the Holland strain, A,
for over two years, and we do not know how much longer
Professor Jones had it in culture ; while the E strain has been
cultivated less than two months. There seems to be no diminu-
tion in the vigor of their growth under continued artificial cul-
tivation, though we do not know whether or not their power of
infecting potato plants has declined. They all still retain this
758 CONNECTICUT EXPERIMENT STATION REPORT, I909-I9IO.
power, however, as determined by recent tests. These strains
are designated by letters, A, B, C, etc., as a matter of easy identi-
fication. They have exhibited some sHght variation in the
luxuriance of their mycelial and conidial development, and even
more in the matter of oospore production. A short description
of their source of origin, development, etc., follows :
Strain A. This was obtained about February, 1909, from Jones, who
isolated it from tubers grown in Holland. From this culture we have
grown at least twenty-two generations, represented by many cultures under
varying conditions. It has formed a very fair growth on suitable media,
though it is the least vigorous now of any of the strains. It was the
first in which we noticed the appearance of imperfect o5gonial formation,
though this was perhaps more owing to the medium employed than the
strain, since the B strain soon afterwards gave even better results in the
same medium. It now stands about fourth in the matter of oospore produc-
tion, being less variable than D, but the oospores produced are never very
abundant, and are usually imperfect.
Strain B. This culture was isolated by the writer in November, 1909,
from tubers furnished by Mr. Ellicott Curtis, and grown at Bantam,
Conn., that year. His crop had been sprayed during the season and kept
green until late in the fall, when the rains washed off the spray, and the
blight got a foothold too late to injure the vines much, but enough to
thoroughly infect the tubers, which were dug very late, and found
to be badly rotted. We have grown this strain for at least nineteen genera-
tions, perhaps in more cultures and under more dififerent conditions than
any of the other strains. It makes a good vigorous growth, perhaps the
best of any, though not always the most luxuriant. On the whole, the
best results in oospore production have been obtained with it. The most
perfect oogonia, antheridia and oospores have also been found in cultures
of this strain.
Strain C. Cultures of this strain were obtained by the writer in January,
191 0, from infected tubers purchased at a Westville grocery, and probably
grown either in Maine or Long Island. About fifteen generations have
been grown in cultures after the manner of A and B. For a long time
this strain gave no indication of oogonial formation, though grown con-
tinuously on the medium most favorable for that purpose. About the
tenth generation immature oogonia were first noticed, and succeeding
generations developed these better and more abundantly, until finally
antheridia also began to appear, and somewhat rarely, mature oospores.
At present it ranks about third as regards oogonial development. It ranks
high in conidial production.
Strain D. This strain was separated by the writer in October, IQIO,
from the descendants of diseased tubers obtained from Mr. Curtis (see
Strain B) and grown in 1910 on our experimental farm at Centerville.
It has the general characteristics of B, and has given some cultures with
a good development of oogonia, antheridia and mature oospores, but as
OOSPORES OF POTATO BLIGHT. 759
yet it seems much more variable than B in this respect, and so not to be
depended on, though it has not been in culture nearly so long, as it has
been carried through only seven generations. However, it now stands
about second in oospore production.
Strain E. Mr. Stoddard obtained this strain in February, 191 1, from
Maine grown tubers purchased at a local grocery. As yet it has not been
thoroughly tested, as comparatively few cultures have been made, repre-
sented by only three generations, but in these oogonial production has not
made its appearance even in a slight way.
Media. Synthetic media, because of known composition, offer
the best means for determining the cause of oospore production,
if such depends on some particular chemical substance or element.
Yet such media, especially when in liquid form, are not as favor-
able for general growth of fungi as media containing vegetable
nutrients whose ingredients are quite complex and whose exact
chemical nature cannot be determined. Consequently, we have
not used synthetic media except in the sense that certain sub-
stances of known composition have been added to our vegetable
media to determine their individual effect. Potassium and phos-
phorus are more or less fixed in literature as having importance
in vegetable reproduction, and yet we have not in any way by
the addition of potassium phosphate increased oospore production
in our cultures. Likewise, toxic or stimulative substances have
an influence on vegetative growth, yet such substances as we have
tried in a small way, copper sulphate, chloroform, ether, etc.,
have given no response in increased oospore production.
Various Media. Most of our cultures have been on vegetable
media, usually in combination with agar-agar. We have tried
some few liquid media, but they have shown no special advantage,
such as might be expected from the supposed relationship of
Phytophthora and Pythium, and the reported favorable develop-
ment of the oospores of the latter in liquids. Likewise, we have
not found gelatine a favorable medium in what little use we
have made of it, though this was used largely by Jones in his
cultures. In our work, besides various agar-agar media^ we
have tried a considerable variety of substances and combinations.
We have used living aseptic vegetable tissues and quite a num-
ber of sterilized ones, either in whole or ground condition. We
have also used filter paper soaked with nutrient liquid. Taking
into consideration all of the various media, and their modifica-
53
760 CONNECTICUT EXPERIMENT STATION REPORT, I909-I9IO.
tions, we have tried about seventy-five different combinations
in over 1,200 cultures.
Most Favorable Media. Out of all these combinations, three
media stand out as being especially favorable for the growth of
the fungus. Of these the Lima bean juice agar was described
in a previous paper. (Report, 1908, p. 898.) This has never
given us mature oospores, and immature ones only once. A
second very favorable medium for aerial growth of the fungus,
perhaps the most favorable of any we have used, is a "combina-
tion medium" consisting of the following ingredients, ground to
powder in a food-chopper: Lima beans, 15 grms. ; oats, 25
grms. ; peanuts, 10 grms,; potato, 15 grms.; sweet com, 10
grms. ; wheat, 10 grms. ; with agar, 10 grms., and water, 500 cc.
This, however, has shown no special virtue so far as oospore
production is concerned. Potato juice agar gives a fair mycelial
growth of the fungus, but not as luxuriant or vigorous as the
other two media mentioned here. It needs to be used for the
best development somewhat stronger than we first tried it, and
we are now using at least 300 grms. of the sliced tubers to 500 cc.
of medium. But potato juice agar, like the preceding, has so
far been of no value in producing oospores. The one medium
that has stood alone so far as production of oospores is con-
cerned is our oat juice agar. Without this, apparently, we
would never have produced perfect oospores in cultures.
Oat Juice Agar. We have varied somewhat from time to
time in the manner of making this, but in order to have as uni-
form a product as possible, we have finally adopted the following
method: Fifty grms. of ground oats, such as are ordinarily fed
to horses, are stirred into about 300 to 350 cc. of water, and
steam from an autoclave, by means of glass and rubber tubing
connected with the stopcock, is run into this in a covered dish
for half an hour. This cooks the material without burning and
at a uniform temperature. The coarse sediment of the oats is
then strained off through an ordinary fine wire strainer, and 10
grms. agar is added to the liquid, which is again treated to the
steam for half an hour to thoroughly melt the agar. Some water
passes over with the stream during these cookings, so that what
little, if any, is needed to bring it up to the required 500 cc. is
added after the whole is drained into a graduated cyclinder.
After the added water is uniformly distributed by repouring, the
OOSPORES OF POTATO BLIGHT. 761
medium is placed in the test tubes and these are sterilized in the
autoclave for fifteen minutes under 7 to 10 lbs. pressure.
Chemistry of Oats. We are not sure what particular ingredient
of oats, if any, is responsible for stimulating oogonial develop-
ment in the oat juice agar. Chemical analyses of oats show
that they have higher percentages of ash, fat, and lecithin than
the other cereals. Taking the ash content, however, it seems
that this higher per cent, is due largely to silica, so that the per-
centages of phosphorus and potash are even lower than in most
of the other cereals, as well as in beans, though perhaps higher
than in potatoes. So these constituents of the ash are apparently
not the favorable factors. While the licithin is higher than in
the other cereals and potatoes, it is lower than in beans. On
the other hand, the fat is considerably higher than in the beans,
or any other cereal except conii, which it slightly exceeds.
Lecithin is phosphorized fat (contains fatty acids, cholin and
esters of phosphoric acid), and is more soluble than ordinary fat,
being the form in which it is said by some to be digested.
According, to Loew* : "By the transformation of fatty matter
into lecithin the higher fatty acids are offered to the protoplasm
in a soluble form, and after being oxidized, other molecules of
fatty acids may enter into the place of the former, and thus the
same molecules of the glycerol-phosphoric acid can serve repeat-
edly as vehicles for the oxidation of fatty acids." In this man-
ner the amount of lecithin really available in the oats, because
of the much higher per cent, of fat, may greatly exceed that of
the bean. Lecithin also, according to Loew, has considerable
therapeutic value in cases of nervous debility, and is a high con-
stituent of the nervous system (and it is also a prominent
constituent of the spermatozoa of animals), and this might
explain its value in stimulating the potato blight to sexual repro-
duction, especially in its effect on the antheridia, which seem to
have most nearly disappeared.
Fat alone, possibly because not available for the fungus, does
not explain the production of these oospores, since com, though
but little lower than oats in its fatty content, did not stimulate
their production. Likewise peanuts, very high in fat and prob-
ably higher in lecithin, failed to even produce a mycelial growth
of this fungus, though several other fungi grew rather vigor-
*Bull. 45 Bur. PI. Ind. U. S. Dept. Agr.
762 CONNECTICUT EXPERIMENT STATION REPORT, I909-I9IO.
ously in the peanut juice agar. The fat is so evident in this
medium that it shows plainly, even when only 25 grms. of ground
peanuts are used per 500 cc. of medium, which is not the case
with our oat juice agar. While the comparatively high per cent,
of fat in oats, and the possibility of its easy conversion into
lecithin, might explain the phenomenon of oospore production
in the potato blight fungus, we have no sure proof that this
is so. In any case the fungus seems to "feel its oats" more
or less.
Likewise, this oat medium seems to stimulate ordinary spore
production with some other fungi. For example, Monochcetia
Desmazierii fruits abundantly in it, whereas it does not fruit
at all, or very little, on several other media in which we have
grown it. We have also several times had the sclerotia of
Sclerotinia Libertiana attempt to form its asco stage in this
medium, by developing long stalks which just fail to expand
and develop the terminal fruiting cups. Several other fungi also
produce in this medium a more luxurious fruiting condition than
they do in the other media in which we have grown them.
Environmental Factors. Having secured this favorable medium
and using the various strains at hand, we have attempted to
determine if certain changes in the medium or its surroundings
might not act more favorably on oospore production. We will
briefly discuss these factors in the following paragraphs. In
summary, however, it may be stated that we have not found any
very decidedly favorable factors, though there seem to be "ten-
dencies" in certain directions, and that as yet we fail to uni-
formly insure or gradually increase oospore production by taking
advantage of these apparently favorable conditions.
Acid versus Alkaline Media. As made up by us, oat juice
N
agar takes about 15 cc. of — NaOH to neutralize 250 cc. of the
natural medium, as determined by the phenolphthalein test. In
order to test the effect of acid, neutral, and alkaline oat agar
the following strengths were made at different times and the
potato blight fungus grown in them: (i) 15 cc. acid (natural
N
medium) ; (2) 5 cc. acid (used 10 cc. of — NaOH to neutralize
N
250 cc. of medium) ; (3) neutral (used 15 cc. of — NaOH,
OOSPORES OF POTATO BLIGHT. 763
etc.) ; (4) 5 cc. alkaline (used 20 cc. of — NaOH, etc.) ; (5)
15 cc. alkaline (used 30 cc. of — NaOH, etc.) The strains
A to D acted somewhat differently on these five strengths,* but
as a rule vigorous mycelial growth occurred only on the 15 cc.
and 5 cc. acid, and practically no growth on the 5 cc. and 15 cc.
alkaline tubes. However, by gradually acclimating the various
strains through the different strengths from the natural 15 cc.
acid, they were all finally brought so that they would grow
more or less on the 15 cc. alkaline tubes.
As regards oospores, they formed less abundantly and more
im.perfectly on the alkaline tubes than they did on the acid tubes.
On the whole, perhaps the 5 cc. acid tubes gave the best results,
though in some of the comparative tests the 15 cc. acid and the
neutral media did as well or even better. We had thought that
perhaps a slightly alkaline medium would favor oospore produc-
tion, since in previous work with the Lima bean mildew (P. Pha-
seoli) we had found that by making the medium slightly more
acid we had first cut off oospore production, then conidial, and
finally the mycelial development itself, and our first results with
the potato blight seemed to indicate that a neutral or less acid
medium than the natural oat juice agar favored better oospore
development. Out of the total of our experimentations, how-
ever, we can only say that alkaline oats agar is apparently less
rather than more favorable, and that between neutrality and
15 cc. acidity is the best condition for oospore production as
far as this particular factor is concerned.
Light and Darkness. Some investigators have found that
light favored spore germination in the smuts. We tried strong-
light, partial and total darkness, to see if light or its absence
had any effect on oospore production. Cultures kept in a jar
exposed to full light of a north window made a less vigorous
growth than those kept in an adjacent jar entirely protected
from the light, while neither did quite as well as the cultures
kept under our usual conditions of partially diffused light (in
the same room in a glass front cupboard in open tin cans, for
*For instance, one tube of C grew fairly well on the 15 cc. alkaline
tube when transferred directly from the 15 cc. acid tube.
764 CONNECTICUT EXPERIMENT STATION REPORT, I9O9-I9IO.
convenience in holding them). Neither did those cultures
exposed to the stronger light or those in total darkness show
an increase in oospore production, as the difference, if any, was
in favor of our ordinary conditions of partially diffused light.
Temperature. The fact that ordinarily we have found the
oospores of P. Phaseoli on beans in the fall, about the time of
the first frosts, indicated, as is the case with many other fungi
which develop their mature stage in late fall or early spring,
that cold is an important factor in the production of the sexual
stage. Our experiments along this line, however, gave no indi-
cation that oospore production in the potato blight could be
stimulated in this manner. Comparative tests were made, and
repeated with similar results, under four different conditions of
temperature, the temperatures being taken three times a day
during the duration of the tests, (i) Cultures were kept in
an incubator varying from 29 to 33° C, and averaging 32.6°.
(2) In another incubator they were kept at a temperature of
24 to 27° and averaging 24.6°. (3) Check cultures were kept
under our ordinary room conditions of 16 to 22°, averaging
19.4°. (4) Cultures were kept in a box connected with an
indirect ventilator to the outside of the building, in which the
temperature ranged from 1.5 to 20°, averaging 14.5°.
The results of these tests showed that the fungus failed to
grow at all in the higher temperatures of the incubators. The
best growth was made under our ordinary room conditions, where
the temperature averaged 19.4°. The cultures that were kept
in the low and quite variable temperature, averaging only 14.5°,
did very well and made fair growths despite these conditions.
It would seem that the best temperature conditions for mycelial
growth of the fungus were between 1 5 and 20° .
These temperature tests agree with the general prevalence
of the disease in our more northern temperate regions, and its
most severe outbreaks in seasons that are slightly below the
average in temperature as well as above it in moisture. How-
ever, in spite of the great variability with those cultures grown
under the colder conditions, there was no indication of increased
vigor in oospore production. In fact, these tubes did no better,
if as well as the check tubes, under our ordinary temperature
conditions. Low temperature, then, does not seem to be the
factor determining oospore production in this case.
OOSPORES OF POTATO BLIGHT. 7^5
Air. So far as we have seen, oospore production takes place
in the medium sHghtly below or at the surface of the agar. In
fact, this, as well as most other fungi when grown on agar
media, makes only a slight invasion into the medium itself.
Jones, in his experiments with this fungus, however, seems to
have used stab cultures to a very large extent, and here the
oospore-like bodies were produced deep in the medium, away
from the air. We have not used stab cultures largely, but so far
as we have tried them we have not obtained odspores as abun-
dantly or as perfectly developed as in the ordinary agar slant
tubes. Jones, however, used gelatine in the place of agar. We
have not used this in our work nearly so much as the agar, but
so far as we have tried it we have not found it as desirable as
agar. It would seem from our work that the exclusion of the
air by stab cultures in gelatine media was not necessarily a favor-
able factor in oospore production, and that Jones got his results
in spite of, rather than because of, this condition. Possibly the
strains he used were the real factors in his partial success.
Moisture. Moisture seems to be a very important factor in
the spread of the potato blight fungus, since infected leaves of
a plant, if kept in a dry atmosphere, develop the disease no
further. Likewise, in cultures there seem to be certain condi-
tions of moisture most favorable for success, but here excessive
moisture is as imfavorable as too little moisture. Cultures inocu-
lated into the base of a tube containing water do not do so well
as those inoculated above and kept free from the water. Like-
wise, as a general rule, cultures inoculated toward the base of
a tube do better than those inoculated in the drier upper edge.
We have had the best results by inoculating the tubes at the
base, if not bothered by water there, inserting a small amount
of the medium with the fungus, and slightly imbedding this
into the agar.
The chief difference in a tube seems to come in the production
of the oospores, which if present are most likely to be found
in the upper and drier part of the tube. Whether the passing
of the fungus from the more moist lower portion into the upper
and drier portion (dries out quicker because thinner) explains
this we do not know. We do know that the use of either a
more or less dilute agar (we ordinarily use lo grm. to 500 cc.
of water) does not increase oospore production to any appre-
766 CONNECTICUT EXPERIMENT STATION REPORT, I909-I9IO.
ciable degree. We have tried rolled tubes in a few cases, inocu-
lating them at the base. These dry out much quicker than the
ordinary slant tube, but we cannot say that they gave us any
very unusual results. We have also tried running the water,
when present in the base of the tubes, over the growth occasion-
ally, and have pulled off the aerial growth every few days, but
neither of these methods gave us unusual results as regards
the oospores. We have also tried growing the fungus in Petrie
dishes, which offer a difference in moisture conditions, but our
luck here has been no better than with the tubes.
While speaking of the Petrie dish cultures we might mention
that we devised methods by which, with temporary slips of paraf-
fined paper, we could pour a plate containing from two to four
different kinds of media. Inoculating these at the center, the fun-
gus gradually spreads out over theSe different media; or by a
special contrivance it can be made to pass successively from one
kind to another. But these variations have not given any par-
ticularly favorable results in oospore production.
Clear versus Sedimentary Media. Besides stab cultures in a
gelatine medium, a third factor in which Jones' methods have
differed from ours has been his use of a clear or filtered medium,
while we have largely used sedimentary media, in which only
the coarser food particles have been filtered off. That his use
of filtered media does not explain his partial success in imperfect
oospore production seems apparent, since we failed in our previous
experiments to obtain oospores under conditions employed by him,
so far as the use of stab cultures in a filtered, potato juice gelatine
goes. So it must be some other factor than this that gave him
oogonia where we failed to obtain them. In fact, we have found
with our oat juice agar that the sediment in the medium favors
rather than retards oospore production.
On several occasions we have placed a batch of hot oat agar
in a centrifuge and whirled it in the machine for ten to fifteen
minutes, until it hardened, when we have been able to cut off
the upper perfectly clear portion from the lower portion contain-
ing the extra sediment. Comparative cultures made in tubes
of the clear and sedimentary portions have always shown that
the fungus makes a much weaker growth in the former, and
so far no signs of oospore formation have been found in it,
while in the sedimentary tubes the mycelial growth and oospore
OdSPORES OF POTATO BLIGHT. 767
production remain about the same as in our ordinary tubes, from
which they differ only in a Httle more sediment. Tubes made
from oats in which none of the coarse sediment is removed
also act about the same as our ordinar}^ tubes with only the finer
sediment present. Since it might be that the clear tubes were
very deficient in soluble food matter, we have made cultures in
which the ground oats were soaked over night in water, pro-
tected from bacterial action by chloroform, and then used,
this for making the oat juice agar. The clear and sedimentary
portions of such a medium, separated in a similar manner in
the centrifuge, showed no different results than before on inocu-
lation with the fungus. It seems from these experiments quite
evident that the fungus gets from the solid food particles in the
sediment something favorable not only for more vigorous
mycelial development, but also for inciting moderate oospore
production. Whether or not it is the fat, which might be held in
greater amount in the sediment, we have not determined.
Variability of Oospore Production. Despite the fact that oat
juice agar will usually produce oospores with most of our strains,
while Lima bean juice agar practically fails to do so, there still
remains much to be desired in stability and productiveness of
oospore formation in this favorable medium. In fact, we are
never sure even now when Ave make a culture from a very good
tube as regards oospores that its descendant tube will be equally
good. While our success in obtaining oospores to-day is much
greater than it was over a year ago, when they first began to
appear, it is only in looking back over this long period that we
notice improvemerrt, since cultures made a month or two ago
may have been even better than those of recent date.
Variability in the Same Tube. Just what causes this varia-
bility of oospore production we do not know, since it manifests
itself even in the same tube. We have mentioned before that
ordinarily we are more likely to find the oospores at the top of
the culture than anywhere else. We may take out for micro-
scopic examination small pieces of the medium from several
different places, and find no oospores, or only a few, and then
we may strike a spot where they are rather common. This may
be due to the fact that localized portions of the mycelium are
concerned in their production, and that these are scattered. We
have some evidence in favor of this view in the oospore pro-
768 CONNECTICUT EXPERIMENT STATION REPORT, I909-I9IO.
duction of P. Phaseoli, where we find oospores more abundant
in some places than in others, and occasionally we find them
developed in more or less luxuriant bands, so evident as to be
detected by the naked eye. Yet with this species it is rare that
they do not occur very abundantly in every slide made from the
surface of an oat agar tube; while the opposite condition is
more likely to be true of the potato blight. Perhaps this restric-
tion and scarcity in the case of the potato blight is due to their
development in certain spots where the available food, especially
in the sediment, is most abundant.
Variability in Different Tubes. We have also found that cul-
tures made from the same source into tubes of the same batch of
the medium may vary considerably. Perhaps variation in dif-
ferent batches of the same medium might be accounted for by
some very slight variation in the manner of making, but we
would hardly expect this to hold true in the same batch unless
it was some variation in the settling of the sediment, too slight
to be detected by the eye.
We have tried to increase oospore production by propagating
from tubes showing the greatest luxuriance in their development.
While there seems to be something in this, still on the whole
we have no very clear proof of it. Perhaps one difficulty in
the way is that in these renewals we are never sure that we have
used a portion of the culture that was richest in oospore produc-
tion, since it is usually impossible to detect their presence with
a hand lens in our uncleared media. With Jones' cleared gelatine
media, however, this method of renewal was more feasible,
as the oospore groups were quite evident with a hand
lens, and this may account for such success as he has attained by
his continued use of these oogonial groups.
Age of Cultures as Regards Oospore Production. As a usual
thing, with our oat juice agar cultures we can find immature
oospores in the tubes, if such appear at all, two weeks after
inoculation. With P. Phaseoli mature oospores are usually
quite abundant by this time. In order to be sure, however, we
have usually examined the tubes again about a month after
inoculation, as the oospores are then frequently more mature
and abundant. One of the very best tubes produced showed
about a hundred oospores, in different stages of development,
on a single slide from it. Ordinarily, however, the number of
OOSPORES OF POTATO BLIGHT. 7^9
oospores does not ran over from six to twenty on a slide, and
most of these are imperfect. A slide that will give two or three
oogonia from which mature oospores can be crushed out is
considered a good one. Most of the oogonia fail entirely to
mature, apparently through lack of fertilization. Those that
reach maturity with a perfect oospore usually have attached
a well-developed antheridium. Whether or not we can develop
oospore production to the luxuriance which is the usual thing
with P. Phase oli in both Lima bean and oat juice agar, time only
will tell. What we are sure of so far is that we have produced
perfectly matured oogonia with normal and apparently functional
antheridia, and that the oogonia in such cases have often con-
tained mature and apparently functional oospores. As yet we
have not germinated these oospores, but this is equally true of
those of P. Phaseoli, as it apparently takes an exposure to win-
ter conditions to bring about germination.
Microscopic Characters of the Oospores. We have not been
able to follow the different steps in the development of these
oospores as closely as in the bean Phytophthora because of their
comparative scarcity. In general the oogonium develops as a
much more prominent factor than the antheridium, since the latter
is so frequently missing. Then, too, the oogonium seems to be
able to attain a much more advanced stage of development inde-
pendent of any fertilization than does P. Phaseoli, if we can judge
by the size and condition of the oogonium in the latter when
the antheridium first appears. The oogonia of the potato fungus
(see Plate XXXVIII) first made their appearance in our cul-
tures as swollen terminal threads, cut off from the normal myce-
lium by a septimi. Not infrequently, by bif ucation of the mycelial
thread, there were two of these swollen bodies together. The
terminal portion of these swollen threads gradually assumes
a globular shape and is cut off from the rest of the thread. In
the meantime the swollen thread, especially its spherical tip,
becomes more or less deeply tinted. The wall is thickened by
the deposition on the outside of the original coat of a more or
less irregular, thick, reddish-brown coat (see Plate XXXVIII J).
The protoplasmic contents of the oogonium may now begin to
contract into the oosphere. If no antheridium is present, how-
ever, this seems to be as far as the development toward an oospore
proceeds, and this is the fate of most of the oogonia.
77° CONNECTICUT EXPERIMENT STATION REPORT, I909-I9IO.
When an antheridium is present (see Plate XXXIX), it is
very similar to those of P. Phaseoli. We have not yet been
able to detect antheridia in their younger stages, having seen
them only when they were practically mature, and the oogonium
is then well along in its development. With P. Phaseoli we
found that the antheridium was matured, as to size and general
appearance at least, when the oogonium was just beginning to
develop. (See Report, 1908, Plate LXXIV E.) Perhaps a
similar condition would exist with the potato fungus if the
antheridia were produced as abundantly. The presence of the
antheridium further stimulates, apparently through fertilization,
the protoplasmic contents into forming a definite spherical
oospore with a thin limiting cell wall, which gradually thickens
until there is formed a perfectly normal oospore. Plate
XXXIX F shows an oogonium crushed open to reveal more
plainly its enclosed oospore, well filled with protoplasmic con-
tents. In this case the oogonium, antheridium and oospore are
certainly as perfect as any of those ever produced by P. Phaseoli
(see Plate XL A-C).
The thick, colored, outer wall of the oogonium sometimes
becomes so opaque (see Plate XXXIX D) as to hide all signs
of its oospore. This outer coat is also quite variable in thickness
and in the irregularity of its markings. Apparently the medium
in which it is grown has some effect on the irregularity of the
markings as Jones got some apparently quite abnormal sculptur-
ing on those grown in his potato gelatine medium. Then, too,
the outer wall is somewhat brittle, and, when slightly crushed
under a slide, the thick walled oogonia appear more irregular
than they really are. If these oogonia were produced in the
plant tissues we doubt if the outer wall would be as thick, or
present as great irregularities of surface as it does in the
artificial cultures. Some of the oogonia, however, are very
nearly smooth, and some have rather thin walls or thin places.
The oospores have a medium to rather thick wall when mature.
This wall is smooth and hyaline, though in some cases we have
seen a slight tint and some unevenness of surface. Those we
have measured vary from 24 to 35 fi in diameter. The oogonia
vary from 34 /x to 50 fx, mostly 38 to 42 ix, depending somewhat
on the thickness and irregularity of their outer coat. The
antheridia are usually somewhat irregular-oval in shape, vary
OOSPORES OF POTATO BLIGHT. 771
in size usually from 14 — 25 X 12 — 18 /x, and, like P. Phaseoli,
often show the superimposed oogonial thread (see Plate
XXXIX D-F). We have not been able to trace the point of
origin of antheridium and oogonium, but they seem to come
from separate threads, and perhaps it is the contact of these
threads that stimulates the beginning of their development, as
seems to be the case with P. Phaseoli.
Hybrids. In our Report for 1908, page 900, we described
attempts to produce hybrid oospores of P. injestans and P. Pha-
seoli by inoculating a tube of Lima bean juice agar above with
the former and below with the latter fungus. At first we v/ere
inclined to believe that such a hybrid resulted, as in, around,
and below the P. injestans colony there were developed numerous
oospores. As these did not differ essentially from those of P.
Phaseoli, however, we finally came to the conclusion that they
all belonged to the latter fungus.
When, however, in our present work we tried this same cross-
ing on oat juice agar, the results were entirely different, since
we obtained oogonia, usually only in the vicinity of the P.
injestans colony, which were entirely different from the normal
oogonia of P. Phaseoli that were produced abundantly all
through the culture. These different oogonia were oj the P.
injestans type, which at that time we were just beginning to get
in a small way in our pure cultures of P. injestans on oat juice
agar, and they differed in that they usually produced mature
oospores, and were jar more abundant than we have ever
obtained them in pure cultures oj P. injestans. Plate XL shows,
in the upper row, the oogonia of P. Phaseoli as grown in Lima
bean juice agar; the second row shows these P. Phaseoli
oogonia as grown in a cross culture in oat juice agar with P.
injestans; while the two lower rows show the hybrid P. injestans
oogonia as appearing in the same culture with those of P. Pha-
seoli shown in the row above. These photomicrographs easily
convince one that the hybrid oogonia are of an entirely different
type from those of P. Phaseoli, and that they closely resemble
those of P. injestans, as shown in Plate XXXIX A-F.
As stated before, they differ from those of P. injestans in
their greater abundance and more perfect development, espe-
cially of the oospores. They also differ, perhaps, in not being
so deeply tinted, and there are some that seem to grade into
772 CONNECTICUT EXPERIMENT STATION REPORT, I909-I9IO.
P. Phaseoli, or at least are not very different from those of that
species, as the oogonial walls are only slightly tinted and thick-
ened. In one of these cross cultures we measured fifteen
oogonia and oospores each of P. Phaseoli and the hybrid P.
infestans, and found that in the former the oogonia varied from
24 to 34 /i, averaging 29 fi, and the oospores from 18 to 26 /a
averaging 22.5 ja, while the oogonia of the latter varied from
34 to 47 IX, averaging 40 ix, and the oospores from 25 to 35 /*,
averaging 30 /x. These hybrids, then, are about the same size
as the uncrossed oogonia and oospores of P. infestans when
fully matured.
We have crossed most of the strains of P. infestans with P.
Phaseoli on two diiferent occasions. Some of these cross cul-
tures have been much better than others as regards production
of the hybrid oospores. We have continued these hybrids in
renewal cultures in some cases through six generations. Plate
XL, L, shows one of these oospores in the fifth renewal from
the original cross. It does not look essentially different from
the original hybrids, as its lighter color is not lighter than some
that were produced in the original crosses. Now in these
renewal cultures from the original cross, the oospores are not
descendants of the hybrid oospores, since these never germinate
in the cultures, but apparently are merely new crosses each time,
and so are produced only by the conveyance of the mycelia of
both species, which became closely mixed in the original cul-
ture. All of the renewal cultures produce an abundance of the
normal oospores of P. Phaseoli, and those cultures which pro-
duce few or none of the hybrid oospores are therefore ones
in which the P. infestans mycelium has been largely or entirely
crowded out by that of P. Phaseoli.
Of course there are those who may think that these oospores
are not hybrids, but true oospores of P. infestans which have
been stimulated to oospore production in some way by the
presence of P. Phaseoli, just as the oat juice agar has stimu-
lated this production to a less degree. We do not believe this
to be the case, however. The potato blight has evidently lost
its power of antheridial development much more completely
than it has its oogonial development. The history of all our
cultures shows this to be so. In these cross cultures, the
antheridia of P. Phaseoli take the place of the missing ones of
OOSPORES OF POTATO BLIGHT. 773
P. infestans when situated more favorably to the potato oogonia
or oogonial threads than they are to their own. Naturally they
are more favorably situated on the whole to their own than they
are to those of the potato, and so the hybrids are much fewer
in number.
Not only has P. infestans been crossed with P. Phaseoli, but
also with P. cactorum. Our results in crossing with the latter,
however, have not been nearly so satisfactory, as comparatively
few hybrids were found in the cultures, and only where the
B and the D strains were used. We think that this is probably
due as much to mechanical difficulties in having the antheridia
of P. cactorum free to fertilize the oogonia of P. infestans, as
to physiological incompatibility. Our cultures of P. cactorum
on oat juice agar run almost entirely to oospore production, with
little or no aerial growth of mycelium and conidiophores. This
makes it probable that the antheridia are much more favorably
situated to fertilize their own oogonia than those of P. infestans,
so that the chances of crossing are thereby greatly lessened.
Those hybrids that were formed were of the potato type, but
were not nearly so deeply tinted as those obtained with the bean
Phytophthora, being more of a golden than a chestnut brown.
Photomicrographs of the normal oospores of P. cactorum
in a cross culture with P. infestans are shown in Plate XXXIX J
while K of the same plate shows one of the hybrid oospores.
Four of the hybrids had oogonia varying from 35 to 40 /x, and
oospores from 25 to 28 ijl, while the variation of P. cactorum
in the same culture was 20 to 35 fi for the oogonia and 18 to
28 fi for the oospores. The oogonia and oospores of P. cactorum
are very similar to those of P, Phaseoli, being hyaline, smooth,
and moderately thin- walled. Sometimes the oogonia of both
these species become slightly tinted.
Theories. At one time we suggested as a reason for the
absence of the oospores of potato blight in nature and cultures
that there might be male and female mycelial strains and that
oospore production could therefore take place only when these
occurred together. So far as our culture work has gone with
both P. Phaseoli and P. infestans, this theory does not seem
to hold good, as we explained in our last Report.
The more probable theory is that the potato blight fungus
has, at least in most instances, lost its power of sexual repro-
774 CONNECTICUT EXPERIMENT STATION REPORT, I909-I9IO.
duction to af large degree. This is shown by failure to produce
oospores in media in which both P. Phaseoli and P. cactorum
produce them abundantly. It is further shown by oat juice agar
stimulating the production of oogonia in varying degrees from
imperfect to fully matured specimens, and by the varying
response of different strains of the fungus to this favorable
medium.
That the absense of oospore production is due more largely
to the absense or loss of vigor of the male than the female fac-
tor, is shown by the appearance of oogonia in cultures more
frequently than of antheridia, their evident attempt to form
oospores in the absence of the latter, and their success when
normal antheridia do appear. Likewise, the ease with which
P. infestans crosses with P. Phaseoli seems to be due to the
vigorous antheridia of the latter species.
It is perhaps idle to speculate as to how this loss of sexual
vigor came about, though it may be due to the same cause that
has induced the decline of sexual reproduction in the potato
itself. Very rarely do the blossoms of the potato set seeds,
apparently due largely to the sterility of the pollen. Varieties
long propagated seem to have lost the power of seed production
more completely than those recently originated, especially if the
latter are from a cross with a species nearer the wild condition.
This loss of sexual vigor is explained, at least in part, by the
continued propagation of our cultivated varieties by the asexual
tubers. As the potato blight, so far as is known in nature, carries
over from one season to another only through the vegetative
mycelium in the tubers, it may be that continued asexual propaga-
tion of the fungus in this manner has also resulted in its loss
of sexual vigor, especially of the antheridia.
PLATE XXXIII.
<* ♦
a. Fruit Spot of Apple, p. 723.
b. Pocket Curl of Azalea, p. 724.
FUNGI OF APPLE AND AZALEA.
PLATE XXXIV.
a. Showing an elm defoliated in mid-summer.
b. Appearance of fungus on the leaves.
LEAF SPOT OF ELM, p 717.
PLATE XXXV.
a. Drought injury, followed by fungus, p. 729.
b. Frost injury, p. 730. Healthy
INJURIES OF WHITE PINE SEEDLINGS.
PLATE XXXVI.
a. Pine-Currant Rust, p. 730.
b. Pine-Oak Rust, p. 728. c. Pine-Sweetfcrn Rust, p. 729.
STEM RUSTS OF PINES.
I
PLATE XXXVII.
i^ <^ ... ^mV
^ ifP^^HMk «-^^^^^fe.- .jl^ti^^jkw """^
"M"^J,y -^ -^v
a. Spraying by hand with stationary nozzels.
b. Comparative yields from sprayed (1,3) and unsprayed (2, 4) vines, p. 741.
SPRAYING EXPERIMENTS WITH POTATOES.
PLATE XXXVIII.
■ 'C***. \
b
B
~F^
h—
\y ^S'
>k - — c C
b
L?",
— e
a. mycelium; b. oogonial thread ; c. oogonium; d. ocisplierc; e. oospore;
f. antheridium.
DEVELOPMENT OF OOGONIA OF PHYTOPHTHORA INFESTANS, p 769.
PLATE XXXIX.
A-F. Mature oogonia, oospores and antheridia of P. infesfans, p. 770.
G-I. Oogonia-like bodies found in bliglited leaves and tubers of potatoes, p. 756.
J. Oogonia of P. cactoriivi and K, hybrid of this and /'. infcxiam, p. 773.
OOGONIA, OOSPORES, ANTHERIDIA OF PHYTOPHTHORA sps, etc.
PLATE XL.
A-C, P. Phaseoli grown in Lima bean agar. D-F, P. Phaseoli grown in same tul)e
of oat agar with P. infestans. G-L, Hybrids produced by fertilizing /'.
infesfaus oogonia with antheridia of /*. P/iasro/i, p. 771.
OOGONIA, OOSPORES, ANTHERIDIA OF PHYTOPHTHORA sps.