(navigation image)
Home American Libraries | Canadian Libraries | Universal Library | Community Texts | Project Gutenberg | Children's Library | Biodiversity Heritage Library | Additional Collections
Search: Advanced Search
Anonymous User (login or join us)
Upload
See other formats

Full text of "Fungi and fungicides; a practical manual, concerning the fungous diseases of cultivated plants and the means of preventing their ravages"

' * 
PJ>ATK 1. ANTHRACXOSE OF RASPBKKRY. 



FUNGI AND FUNGICIDES 

A PRACTICAL MANUAL 



CONCERNING THE 



Fungous Diseases of Cultivated Plants 



MEANS OF PREVENTING THEIR RAVAGES 



BY 

Nt. \VKED, D. Sc. 



e library 
of 
B. Thomson 



I 



NEW YORK 
ORANGE JUDD COMPANY 

1896 



f 




By THE SAME AUTHOR 



INSECTS AND INSECTICIDES 

A Practical Manual Concerning Noxious Insects and the 
Methods of Preventing their Injuries. Profusely Illus- 
trated, 280 pages, handsomely bound in cloth with em- 
bossed cover. Price, #1. 25. 



SPRAYING CROPS 

Why, When and How. Illustrated. Second (Revised) Edi- 
tion. Seventh Thousand. 130 pages. Price, 25 cents. 




Copyright, 1894, by ORANGE JUDD COMPANY 



CONTENTS 



Inttatjuction 1 

PART I. FUNGI AFFECTING THE LARGER FRUITS 



Apple 27 

Pear 41 

Quince 47 



Plum 53 

Cherry 66 

Peach . . 67 



PART II. FUNGI AFFECTING SMALL FRUITS 

Grape 79 i Raspberry and Blackberry .. 97 

Currant and Gooseberry 91 | Strawberry 104 

PART III. FUNGI AFFECTING SHADE TREES, ORNAMENTAL PLANTS 
AND FLOWERS 

Shade Trees Ill I Flowers 119 

Rose 114 I 

PART IV. FUNGI AFFECTING VEGETABLES 



Bean 123 

Beet 135 

Cabbage 138 

Celery 144 

Onion 150 

Cucumber and melon 160 



Potato 164 

Sweet Potato 172 

Spinach > 176 

Tomato 179 

Seedlings 182 



PART V. FUNGI AFFECTING CEREAL AND FORAGE CROPS 



Oals 187 

Wheat 194 

Indian Corn 202 



Sorghum and Broom Corn . . . 214 

Alfalfa 217 

Clover 219 



iii 



Nothing illustrates so practically arid satisfactorily the 
importance and value of scientific investigation as the results 
obtained by recent experiments in spraying with arsenites for 
the destruction of insects, and with the copper solution or 
Bordeaux mixture for the treatment of fungous diseases. 
After long and patient study and experiment, scientific experts 
have discovered several causes of the failure of the fruit crop, 
and have recommended remedies which are proving effective 
and reliable. 

These discoveries are of inestimable value, since without 
the remedies suggested the spread of diseases and the ravages 
of injurious insects would soon have put an end to several 
branches of the fruit industry. W. C. Barry. 

The day is not far distant when fungicides, and the means 
of applying them, will be as much a part of the equipment of 
a first-class farm particularly one devoted to fruit or truck 
as is the cultivator or market wagon. B. D. Halsted. 

We shall conquer when we know how. When we, with 
open eyes and unstopped ears, as true students of nature, acquire 
the knowledge within the possibilities of our reach, we shall 
be able rightfully to assert our royal authority and effectually 
to have dominion over every living thing that moveth upon the 
earth. T. J. Burrill. 

The time is rapidly approaching when a farmer or garden( 
will as little dare to neglect the study of the physiology and 
pathology of plants, as a surgeon dare practice without a knowl- 
edge of anatomy, or a sailor hope to become a captain wit 
studying navigation. H. Marshall Ward. 



iv 



PREFACE 



The fungous diseases of cultivated plants inflict annually 
upon American agriculture an enormous loss, a large propor- 
tion of which might be saved by the application of the various 
methods of prevention and remedy now known to be available. 
The purpose of this book is to bring together in easily accessi- 
ble form, the information concerning the injuries, life-histories, 
characteristics and preventives of these diseases, now widely 
scattered through scores of periodicals, bulletins, reports and 
transactions. In preparing it, free use has been made of all 
accessible "writings upon the subject, a list of which would 
include the contributions of nearly every American economic 
mycologist, and of many in other lands. It pretends only to 
the dignity of a compilation in which the compiler has utilized 
both the facts and very often the language of others. 

It would be difficult to find, in the annals of agriculture, 
an instance in which knowledge of the highest practical value, 
concerning a subject of first importance in the successful pro- 
duction of the fruits of the earth, has been so rapidly evolved, 
as has been the case during the last decade, in the investiga- 
tion of plant diseases and their remedies. Scarcely ten years 
have passed since there were barely half a dozen scientific men 
in the United States working upon these problems, from an 
economic standpoint. Of these, perhaps no one was doing so 
much, both in original investigation, and in urging the neces- 
sity that such studies be fostered by the State and general 
government, as Professor T. J. Burrill, of the University of 
Illinois. In 1886 Hon. Norman J. Colman, Commissioner of 
Agriculture, recognized the importance of the subject, by estab- 
lishing a mycological section of the botanical division of the 
Department of Agriculture, and appointed Professor F. Lamson- 
Scribner to take charge of the work. The wisdom of creating 
the section was soon made manifest to the public at large, by 
Professor Scribner's demonstration of the practicability of pre- 
venting the ravages of the black rot of grapes, and other mala- 

Y 



\1 



PUN(iL AM) FUNGICIDES 



dies of cultivated crops ; and the Department has been, ever 
since, the Hurt' crater of interest in the development of knowl- 
edge upon the subject. In 1888, Professor Scribner resigned, 
for a professorship in the University of Tennessee, and was 
succeeded by Mr. B. T. Galloway, under whose administration 
the mycological section has been elevated to the Division of 
Vegetable Pathology, and has constantly increased in efficiency 
and usefulness, now having a corps of trained experts who are 
doing much to alleviate the ills of American agriculture. 

When, in 1888, the experiment stations were established in 
the various States, the subject of plant diseases was at once 
recognized as one of the important lines of work it being, in 
fact, specially mentioned in the organic law upon which they 
were founded and in many stations, investigators at once 
began work upon the problems involved. Although scarcely 
six years have since passed, results of immense practical 
importance have already been obtained in these investigations 
and experiments such as the demonstration of the value of 
the hot water treatment for grain smuts ; of the effects of the 
Bordeaux mixture, and other fungicides, in preventing potato 
blight and rot, as well as the plum leaf -spot, raspberry anthrac- 
nose, apple scab, pear leaf-blight, and many other maladies ; of 
the nature of various onion diseases, and methods of their pre- 
vention ; and of the final discovery of the cause and cure of the 
potato scab. It is safe to say that, had the experiment stations 
done nothing more for agriculture than to obtain these and 
other similar results concerning plant diseases, the money 
spent upon them by the government would have been wisely 
invested. 

The authors, in connection with whose publications the 
illustrations on the following pages originally appeared, are 
indicated in the following list : After Arthur, figures 78, 79 ; 
Atkinson, figure 53 ; Bailey, plates II, XI, figures 10, 11, 21, 32, 
33, 36, 37, 39 ; Beach, plates VI, XIV, XV ; Burrill, figure 87 ; 
Chester, plate IX, figures 9, 88 ; Clinton, fibres 47, 48 ; Dudley, 
plate XIII, figures 22, 23, 65, 66 ; Miss Detmers, plates I, XII ; 
Fairchild, figures 34, 54 ; Farlow, plate III, figure 7 ; Galloway, 
plates IV, VII, figures 8, 31 ; Garman, figures, 16, 18, 19, 49 ; 
Halsted, 17, 20, 24, 46, 57-60, 64, 70-72, 75, 76; Miss Howell, 
figures 89, 90 (in part) ; Jones, figure 73 ; Kinney, plate XVI ; 
Kellerman and Swingle, figures 77, 80, 81 ; Lamson, plate V ; 
Lugger, figure 2; Maynard, plate X; Pammel, figure 90 (in 



PREFACE Vll 

part) ; Scribner, figures 38, 42-44, 50-52, 61-63 ; Seymour, 45, 
86 ; E. F. Smith, plate VIII ; W. G. Smith, plate XVII ; Soraue^ 
figures 13, 14; Thaxter, figures 56, 67-69; Tulasne, figure 84; 
Waite, figure 15 ; Ward, figure 6. 

I have aimed to treat of only the more destructive and 
wide-spread fungous diseases, especially those for which prac- 
tical remedies are known ; and have endeavored to give such a 
concise account of the more important facts concerning these 
as will enable the cultivator to combat them intelligently. A 
few of the paragraphs in the following pages have already been 
printed in my series of articles on Plant Diseases in the National 
Stockman and the American Agriculturist; and in a few other 
instances I have drawn upon my previous writings. I desire 
also to express my obligations to the directors and other offi- 
cers of a number of experiment stations notably those of 
Connecticut, Cornell University, Delaware, Kentucky, Massa- 
chusetts, New York, New Jersey, New Hampshire, Ohio, 
Rhode Island, and Vermont for the use of plates of illustrations. 

C. M. W. 
New Hampshire College of Agriculture and Mechanic Arts. 

Durham, January, 1894. 



FUNGI AND FUNGICIDES 



INTRODUCTION 



Cultivated plants are beset by many enemies. Some 
of these belong to the animal, and others to the vegeta- 
ble kingdom. Of the former the insects, and of the lat- 
ter the parasitic fungi are by far the most important. 
By the development of these parasitic fungi upon grow- 
ing crops the peculiar maladies known as fungous dis- 
eases are produced ; and to these diseases American 
agriculture annually sacrifices a large percentage of her 
products. The money value of the loss thus sustained 
is believed, by those who have studied the subject, to 
amount to hundreds of millions of dollars yearly. 

It is difficult to determine definitely the amount of 
damage inflicted over a wide area upon a given crop by 
its fungus enemies, but it is safe to say that in most 
cases it is much greater than is ordinarily supposed. 
The following examples will serve to illustrate the mag- 
nitude of the loss in the case of certain crops. 

In 1886 Commissioner N. J. Colman, of the United 
States Department of Agriculture, after careful esti- 
mates, stated : " We may safely assume that the value of 
the corn and wheat annually destroyed in this country by 
diseases induced by fungi is not less than $200,000,000." 
The average annual loss due to the rust of wheat in Illi- 
nois alone has been estimated, by Professor T. J. Burrill, 

1 



2 FUNGI AND FUNGICIDES 

at nearly half a million dollars ; and careful estimates 
made by authoritative observers in widely separated 
States indicate that the average yearly loss of oats in the 
United States due to smut equals, or exceeds, one-tenth 
the entire crop. Professor Kellerman estimated the loss 
in Kansas, in 1888, at $1,382,328.31 ; and in 1889, at 
$850,534.76. The loss in Indiana from the same cause, 
in 1889, was estimated by Professor Arthur at $797,526 ; 
and in 1890, at $605,352. 

It is probable that fruits suffer an even greater pro- 
portionate injury than do the grains. "The blights 
and rots of the fruit plantations," said Professor Burrill, 
several years ago, "would, if exactly and certainly ex- 
pressed in dollars and cents, frighten cultivators from 
their business." The loss from apple scab, throughout 
most of the apple-growing regions of the country, ranges 
from one-sixth to one-half of the entire product. The 
strawberry blight, in many localities, often ruins crops 
of this luscious fruit. The rots and mildews affecting 
grapes have led to the extermination of hundreds of 
vineyards. The loss of peaches from the brown rot on 
the Chesapeake and Delaware peninsulas, in 1888, was 
estimated by competent observers at from $400,000 to 
$600,000. Similar statements could be made concern- 
ing nearly all our fruits. 

The vegetable and field crops, the flowers and orna- 
mental plants, and even the shade trees, do not fare 
much better. Nearly all have enemies that cause serious 
damage. Over a large section of country the usual loss 
of potatoes from fungus enemies varies from ten to 
forty per cent, of the crop. 

THE DEVELOPMENT OF PARASITIC FUNGI 

To illustrate the life- history of the fungi causing 
the fungous diseases of growing plants, we will begin 
with a familiar example of vegetable life the Indian 



PARASITIC FUtfGI 3 

corn plant. When a kernel of corn is placed in a 
warm, moist soil, it germinates by sending out a pointed 
tube, called the radicle, or first root. This pushes into 
the soil and, after a time, produces other roots, which 
branch off in various directions. Soon after the radicle 
starts, the little plant also sends upward to the air its 
minute coiled leaves. While germinating, the young 
plant is nourished by the food stored up in the starchy 
portion of the corn kernel, but soon after the leaves 
expand in the sunlight this source of food is exhausted, 
and thereafter the plant relies upon its own resources 
for the materials of growth. By means of the contin- 
ually developing rootlets, it is able to draw from the 
soil certain chemical compounds, such as water, potash, 
phosphoric acid, etc., which are taken up through the 
stem and distributed to the leaves, where, by the action 
of the sunlight upon the chlorophyll or the green por- 
tion of the leaf they are combined with the carbonic 
acid of the air, and these simple chemical substances are 
changed from inorganic to organic compounds, forming 
starch, sugar, and various other products. The plant 
continues growing, storing up in its leaves and stem 
more and more of these highly organized materials which 
it produces as it develops. It finally reaches a point 
where it begins preparing for reproduction ; on the mid- 
dle or lower portions of the stem it sends out its pistil- 
late, or silky blossoms, and on the upper it produces the 
staminate, or tassel flowers. The pollen from the latter 
falls upon the former, and fertilizes the ovaries of the 
embryo kernels. These then begin to develop, and 
much of the starchy and other organic matter stored in 
the stem and leaves is transferred to the cob and kernels. 
The latter finally mature, and the cycle of vegetable life 
is complete. 

This is a fair illustration of the life-history of the 
higher plants. Such plants are especially distinguished 



FUNGI AND FUNGICIDES 



by the presence of chlorophyll, and the ability to con- 
vert the inorganic elements of the soil and air into 
highly organized compounds. But such plants form 
only a part of the vegetable life of the globe. There are 
vast numbers of the so-called lower plants, like the l< tad- 
stools, mushrooms, molds, mildews, rusts, smuts, blights, 
and similar organisms, which are classed together under 
the common name of fungus. The plural of fungus is 
fungi pronounced funji or funguses. Tbese fungi 
differ greatly from, each other; some rank comparatively 
high in the scale of existence, and others rank low. 

As an illustration of the higher fungi, we may take 
one of the mushrooms so common in our fields and 

woods. This plant repro- 
duces by means of spores 
minute bodies, corres- 
ponding in function to the 
seeds of higher plants. 
When one of these spores 
falls upon a moist soil, 
rich in decaying organic 
matter, it germinates by 
sending out a little tube 
much as the kernel of 
corn sends out its germi- 
nating radicle and this 
tube, after penetrating the 
soil a short distance, sends 
out side branches, which push about between the decay- 
ing organic particles, absorbing nourishment from them. 
These branches, in turn, send out other branches, and 
these form what is called the mycelium, or vegetative 
portion of the fungus ; this continues developing be- 
neath the surface for some time. Finally an unusual 
development of mycelium takes place at one or a few 
points, and from these there are rapidly produced a few 




FIG. 1. MUSHKOOM. 



PARASITIC FUNGI 5 

mushrooms, which may be sent up "into the air above the 
soil surface in a single night. Each mushroom (Fig. 1) 
consists of a stem commonly surmounted by an umbrella- 
like cap, on the under side of which are many thin ver- 
tical plates. Between thece plates vast numbers of 
spores are soon produced, to fall to the ground, or to be 
wafted hither and thither by the winds. As soon as the 
spores are ripe the fungus dies. It will be noted that 
this plant has no chlorophyll, 
and is simply nourished by 
dead and decaying organic 
matter. Fungi like this are 
said to be saprophytes, or 
saprophytic, a word meaning 
living on decaying materials. 
Such plants, as a rule, do no 
direct injury to other kinds 
of vegetable life. 

There are many kinds of 
fungi which, instead of living 
upon dead or decaying organic 
matter, develop at the expense 
of other living organisms. 
Consequently these are said 
to be parasitic in their nature. 
Some of these live within the 
bodies of animals, often kill-no. 2. CHINCH BUGS AFFECTED 
ing their hosts, and others BY FUNGUS. 

live within the tissues of the higher plants. A good 
example of the former is seen in the fungus which de- 
stroys chinch bugs, represented in Fig. 2. A number 
of dead bugs are shown on a wheat stalk on the left, 
while a single bug, much magnified, covered with the 
fungus, is represented at the right. This fungus belongs 
to a genus of plants called by botanists Entomophthora. 

To illustrate the manner of development of the par- 
asitic fungi affecting higher plants, we may take the 




6 FUNGI AND I-TN-GICIDES 

downy mildew which 'causes th0 well-known rot of the 

Irish potato. It is now believed that this disease does 
much less damage in America than has been commonly 
supposed, the injury attributed to it being often due to 
other fungi, but it is sometimes destructive, and its life- 
history has been carefully studied. 

The first indication of the presence of the downy 
mildew in the potato field usually is the appearance of 




FIG. 3. DISEASED POTATO LEAF. 



brownish spots upon the leaves. As the disease pro- 
gresses these spots gradually enlarge, finally involving 
the whole leaf, which turns dark brown or blackish. 
Then neighboring leaves become affected, and the whole 
plant eventually wilts and dies. 



PARASITIC FUNGI 7 

If one looks closely at the under surface of the leaf 
beneath the brown spots, he will see, in case this fungus 
is present, a whitish velvety mold. By making a thin 
cross-section of the leaf at this point, and putting it 
under the microscope, an appearance similar to Fig. 4 
will be seen. At the right is one of the long pointed 
hairs which grow naturally upon the under surface of 
the healthy leaf ; next to this toward the left is another 
peculiar leaf-hair with a club-like tip ; and beyond this 




FIG. 4, SECTION OF POTATO LEAF SHOWING DEVELOPMENT OP 
MILDEW. 

project the hyphae, or fruiting threads of the fungus, 
which give off branches on which are borne small oval 
bodies. The latter are the spores, or conidia, of the 
fungus. They are uhe bodies by means of which the 
fungus reproduces itself, and are developed on the 
infested leaves in enormous numbers. 

These conidia are easily dispersed by slight air cur- 
rents, and are carried far and wide en the wings of the 



8 



I i N(,l AND FUNGICIDES 




FIG. 5. POTATO MILDEW. 



wind. When one of them falls upon a moist potato 
leaf it germinates hy a very peculiar method : The 
inside of the spore is composed of a granular substance 
which at this time divides into several individual parti- 
cles, that escape through an opening in the smaller end 
of the spore wall, as seen in b, Fig. 5. Each of these 
particles now develops two minute hair-like projections, 
called cilia, as seen at c, by means of which it swims 
around in the drop of water ; these are called swarm- 
spores, or zoospores. 
After a short time these 
swarm-spores come to 
a rest, absorb the cilia, 
and change from the 
oval shape to one more 
spherical (d) ; each 
then germinates by 
sending out a little 

6, same, with contents escaping: rrorrninafi-n rr fnlip 
ores; d, same, come to rest and e * m J n a l T n g tU DC, 

something as a kernel 
of corn sends out its germinating radicle, as shown in 
the two figures beside d. 

In case these swarm-spores germinate on the surface 
of a potato leaf on or near to one of the breathing pores, 
or stomata the peculiar openings with which both sur- 
faces of most leaves are provided the germ tube passes 
to the interior of the leaf through it, as shown at a, 
Fig. 6. If no breathing pore is in the immediate vicin- 
ity, the germinating spore bores through the cell wall, 
as shown at c. 

After the parasitic fungus has thus entered the 
inside of the leaf it develops rapidly at the expense of 
the tissues of the latter. It pushes its threads, or 
hyphm, about between the cells, choking up the cavities 
which occur in the healthy leaf, and absorbing the con- 
tents of the cells. In many species of Peronospora the 



a, conidium; 
c, swarm spores 
germinating. 



PARASITIC FUNGI 9 

threads that run between the cells send into the cells 
themselves little processes called "suckers," or haustoria, 
which assist in absorbing the cell contents. Thus, in. 
the downy mildew of the grape this occurs in a way 
illustrated at Fig. 7. These threads running through 
the leaf lead to the disorganization of its tissues, causing 
the cells to collapse and turn brown. When they have 




FIG. 6. SURFACE OF POTATO LEAF GREATLY MAGNIFIED, SHOWING 
GERMINATING SPORE ENTERING BREATHING PORE AT a, 
AND GOING THROUGH EPIDERMIS AT C. 

developed to a considerable extent they collectively form 
the mycelium of the fungus. 

After the Peronospora plant has reached this stage 
in its existence it is ready to prepare for reproduction. 
It sends out through the breathing pores of the leaf 
branching threads, and on these develops the conidia, as 
already described. 

By means of these conidia, which are produced in 
great abundance, and the swarm-spores originating from 




10 FUNGI AND FUNGICIDES 

them, the fungus is able to multiply with marvelous 
rapidity during the warm, damp weather most favor- 
able to its growth. "In an ordinary potato field the 
abundant foliage, wet with rain and full of juices 
such as would favor the growth of the mycelium, is 
swayed by the wind, and leaf flaps upon leaf over the 
whole area ; quite apart from the wind-blown conidia, 

the active zoospores can 
soon spread from any one 
center, and at once infect 
new leaves. In a few 
hours fresh disease-spots 
are developed, each put- 
ting forth new crops of 
FIG. 7. SECTION or LEAF SHOWING conidia, which again ger- 

MYCELIUM OF FUNGUS, MAGNIFIED. m i na t e and Send Out ZOO- 

spores, and so on." Under these conditions it is easy 
to see that the attack may be sudden and destructive. 

Besides these conidia, or summer spores, many par- 
asitic fungi develop in autumn certain spores, by means 
of which the fungus passes through the winter. The 
latter are usually better protected than the conidia. 
They are sometimes called winter-spores. 

Besides the saprophytic and parasitic fungi discussed 
above, there are some which partake of the nature of 
both, belonging to one class during a portion of their 
development, and to the other during the rest. For 
example, the black rot of grapes is at first a true parasite 
attacking the healthy parts of the vine, but it completes 
its growth as a saprophyte, living upon the decaying 
berries. 

KELATION OF THE WEATHER TO FUNGOUS DISEASES 

There is a common idea that the weather is respon- 
sible for a large proportion of plant maladies. In an 
indirect way this is often true, but the condition of the 



METHODS OF STUDYING FUNGI 11 

atmosphere never directly causes a fungous disease. 
Such diseases, as already indicated, are produced by 
minute plants, which never arise spontaneously, but 
always from some spore, or other reproductive form of a 
previously existing plant of the same species. But 
weather conditions may be favorable to the rapid devel- 
opment of these fungi, and so indirectly cause the 
diseases. 

METHODS OF STUDYING FUNGI 

The successful study of the minute characteristics 
of most fungous diseases requires the use of a compound 
microscope. These, however, can be obtained for a 
comparatively small amount, and will well repay the 
investment in the wonders revealed. By the aid of some 
such little book as Phin's "How to Use the Microscope," 
or Bausch's "Manipulation of the Microscope," almost 
anyone can learn how to manipulate a microscope, and 
can examine the microscopic characters of the various 
fungi affecting crops. One desiring to undertake such 
study would find the following books helpful : 

Bennett & Murray : Cryptogamic Botany. 

Burrill : Parasitic Fungi of Illinois. 

Plowright : British Urediniae and Ustilaginiae. 

Scribner : Fungous Diseases of the Grape and Other 
Plants. 

Smith : Diseases of Field and Garden Crops. 

Ward : Diseases of Plants. 

The bulletins of the United States Department of 
Agriculture, especially the Journal of Mycology, and of 
the various experiment stations, will also prove very 
useful. 

METHODS OF DISTRIBUTION 

There are many ways in which fungous diseases are 
distributed, although the commonest one is by means of 



12 FU.N<;| AM> I IN(,I< IDKS 

the various kinds of summer spores. With the frrr;ti 
majority of diseases these are produced in countless 
numbers, and as they are wafted hither and thither by 
every breath of wind, are washed from leaf to leaf and 
from leaf to root by rains, and germinate quickly in 
their new situations, they are able to spread infection 
with marvelous rapidity. They are also, no doubt, often 
carried from place to place by insects and birds, adher- 
ing to some part of their bodies, especially the feet. 

The various other kinds of spores produced by the 
fungi discussed in the following pages are also distrib- 
uted by similar agencies. Some of the smuts, as well, 
no doubt, as many other diseases, are often spread 
through the field in barnyard manure ; and in cases like 
the onion smut, the spores may be washed, with loose 
soil, from higher to lower levels. The spores of certain 
grain smuts appear to be able to pass from diseased to 
healthy kernels during the process of threshing, and, 
in some cases, the disease may be spread by means of 
hoes and other implements used in cultivation. 

In diseases like the scab and blight, or rot of pota- 
toes, the mycelium of the fungus is often distributed in 
the tubers used for seed, thus being ready to infect the 
new crop as soon as it gets well started. 

METHODS OF PREVENTION 

There are many ways in which the injuries of fun- 
gous diseases may be prevented. Among the more im- 
portant of these are the following : 

Fertilization and Cultivation. As a general 
rule, not, however, without important exceptions, 
plants weakened in vitality are more subject to the 
attacks of parasitic fungi than those in vigorous growth. 
Consequently methods of cultivation and fertilization 
which tend to produce rapid development and early ma- 
turity, are to be adopted as far as practicable. 



METHODS OF PREVENTION 13 

Selection of Resistant Varieties. It has long 
been observed that with many crops certain varieties are 
more liable to fungous diseases than others. The reason 
of this, in many cases, is not well understood, but the 
fact will lead the careful cultivator to select such varie- 
ties as prove most resistant, other things being equal, in 
his locality. Dr. B. D. Halstead has recently shown 
that plants with variegated foliage are much more sub- 
ject to fungus attack than those with green leaves. 

Rotation of Crops. The spores of the great ma- 
jority of parasitic fungi pass the winter on or in the soil 
where the crop attacked was grown, and if a crop of the 
same kind is planted there the next season it is almost 
certain to be infested. The onion smut is a striking 
example of this. In consequence, the proper rotation 
of crops is not only desirable, but often imperatively 
necessary. The rotation should be so arranged that 
each crop will not be liable to attack from the diseases 
of the preceding crop. 

Clean Culture. Injurious fungi may be largely 
destroyed by keeping the farm premises clean and free 
from weeds and rubbish. Burning potato tops, old 
tomato vines, and similar refuse, will destroy millions of 
spores. Some fungi which infest cultivated crops also 
grow upon weeds, and, hence, keeping the ground free 
from the latter may prove of great benefit to the former. 
Care should also be taken not to distribute the spores by 
means of stable manure. 

Mechanical Exclusion. It is often practicable 
to prevent the spores from reaching the crop by methods 
of mechanical exclusion. The most familiar example of 
this is to be found in the practice of bagging grapes to 
prevent their rotting. Small paper sacks are tied over 
the bunches as soon as the fruit is well formed, and 
allowed to remain until it ripens. The sacks exclude 
the rot spores, and also prevent insect attack. 



14 II N-l AND 



Hand Picking. With diseases like the brown rot 
of peaches and plums, plum pockets, etc., much may be 
done in reducing injury by persistent hand-picking of 
the affected parts, which, of course, should be burned 
or buried deeply in the soil. 

Use of Non-infected Seed. Numerous fungous 
diseases start from the seed. For instance, the potato 
rot exists in seed potatoes, and so infects the new crop. 
In such cases care should be taken to obtain seed not so 
infected, or, when possible, so to treat the seed that the 
spores are destroyed. 

Destruction of Alternating Forms. As shown 
on other pages, some of the rusts exist in two or more 
forms on different host-plants. For instance, the apple 
rust has one form that produces " cedar balls" on cedar 
trees. The destruction of the latter will prevent the 
development of the former. 

Use of Fungicides. The most practicable way of 
preventing the great majority of the fungous diseases of 
cultivated crops is by the use of fungicides (a word 
meaning, literally, killers of fungi). These are discussed 
more fully under the following heading. The majority 
of them are applied externally to plants by spraying or 
dusting. In such cases they may act in either or both 
of two ways : (1) By directly destroying any fungus 
spores present at the time of application ; and (2) by 
remaining on the surface in a condition to destroy, either 
before germination or during that process, any spores 
that may light upon the plant thereafter. 

THE IMPORTANT FUNGICIDES 

The following list includes the fungicides that have 
proved of practical value up to the present time. It is a 
list, however, that will probably be extended during the 
next decade, as experiments are constantly progressing 
to learn the fungicidal value of many other substances. 



THE IMPOBTAKT FUNGICIDES 15 

Water. The use of water heated to 132 F. has 
recently come into practice to destroy the spores of grain 
smuts in or on the seed. The water should not get 
above 135, nor below 130, while the seed is immersed. 
Full directions for this treatment will be found in the 
discussion of wheat and oats smuts. 

Bordeaux Mixture. This fungicide originated 
in France, and has become one of the leading combina- 
tions of copper salts. Since its introduction into Amer- 
ica there has been a constant tendency to dilute the mix- 
ture more and more. The results from the diluted 
mixtures have been apparently as good as from those of 
full strength, and, of course, the cost has been propor- 
tionately lessened. The different formulas are indicated 
below : 

Original Formula. Dissolve six pounds of copper 
sulphate in one gallon of hot water in an earthen or 
wooden vessel. In another vessel slake three pounds of 
fresh lime in one gallon of water. Strain the latter and 
add to twenty gallons of water. Now pour in the dis- 
solved copper sulphate and mix thoroughly. Keep the 
mixture stirred while using. 

Half-strength Formula. In 1889, while at the 
Ohio Experiment Station, I experimented with potato 
blight by diluting this mixture a little more than half, 
using six pounds of copper sulphate and four pounds of 
lime to a barrel (fifty gallons) of water, instead of 
twenty-two gallons. This was applied to a number of 
plants besides potatoes, and, apparently gave as good 
results as undiluted mixtures. The same formula was 
also successfully used in 1890, and has since been quite 
generally adopted, being now recommended by the 
United States Department of Agriculture. Mr. Gallo- 
way suggests the following method of procedure : 

" In a barrel that will hold forty-five gallons dissolve 
six pounds of copper sulphate, using eight or ten gallons 



16 FUNGI AND FUNGICIDES 

of water, or as much as may be necessary for the pur- 
pose. In a tub or half barrel slake four pounds of fresh 
lime. When completely slaked add enough water to 
make a creamy whitewash. Pour this slowly into the 
barrel containing the copper sulphate solution, using a 
coarse gunny sack stretched over the head of the barrel 
for a strainer. Finally fill the barrel with water, stir 
thoroughly, and the mixture is ready for use. Prepared 
in this way the cost of one gallon of the mixture will 
not exceed one cent, the price of copper sulphate being 
seven cents per pound, and lime thirty cents per bushel. 
In all cases it is desirable to use powdered copper sul- 
phate, as it costs but little more and dissolves much 
more readily. It is highly important also that fresh 
lime be used." 

Third-strength Formula. In 1891 Mr. AV. J. 
Green, of the Ohio Experiment Station, used on apples, 
plums, pears, cherries, raspberries, etc,, a still more 
dilute mixture, viz., four pounds of copper sulphate and 
four pounds of lime to fifty gallons of water, and ob- 
tained very good results. The cost of the copper sul- 
phate in a barrel of this mixture is less than one-third 
the cost of that in a barrel prepared according to the 
original formula. 

A still more dilute mixture is recommended by the 
Rural New Yorker, and probably, in some cases, is as 
effective as any of the above, while also cheaper. It is 
"one ounce of copper sulphate and three-fourths of an 
ounce of lime to each gallon of water ; that is to say, 
two pounds of copper sulphate and one and one-half 
pounds of lime to thirty-two gallons of water." A 
special advantage of the Bordeaux mixture is, that Lon- 
don purple or Paris green can be added to it, making a 
combined insecticide and fungicide. 

Care should be taken not to use the Bordeaux mix- 
ture on fruit crops too late in the season. Traces of it 



THE IMPOKTA.NT FUNGICIDES 17 

remain for some time, notwithstanding numerous rains, 
and are liable to cause unnecessary suspicions when on 
marketed fruit. When a fruit crop requires treatment 
within a month of the time of picking, it is better to 
substitute some fungicide like eau celeste or carbonate 
of copper, but it is doubtful if even these combinations 
should be applied so near the time of the fruit haryest. 
"With nearly, if not quite, all of our fruit diseases, the 
treatment should begin early and not continue too late. 

It sometimes happens that traces of Bordeaux mix- 
ture remain upon the fruit, even when a considerable 
interval elapses between the last application and 'the 
ripening of the fruit. Such traces may be easily re- 
moved by dipping in a solution made by adding two gal- 
lons of cider vinegar to ten gallons of water. A good 
way is to have three tubs, one holding the vinegar mix- 
ture, and the other two pure water. Then place the 
grapes or other fruit in wire baskets holding fifteen to 
twenty pounds, dip them in the vinegar tub for five 
minutes, and then rinse in the two tubs of clear water, 
afterwards spreading the fruit on frames or shelves, 
something like those used in fruit evaporators. Grapes 
can be treated in this way on a large scale for six cents a 
hundred pounds, and their appearance for market is not 
injured to any appreciable extent. 

The Bordeaux mixture must be kept well stirred in 
the reservoir during application. A paddle in the bar- 
rel, something like that of an old-fashioned churn, is 
one of the most efficient agitators. The addition of 
enough soap to make a slight suds has been recom- 
mended, as causing the mixture to spread more evenly 
over the plants. 

Eau Celeste. This is made by dissolving two 

pounds of copper sulphate in six or eight gallons of 

water in an earthen or wooden vessel (such as the large 

crocks used for butter, or wooden pails or tubs), then 

2 



18 I I N,l AM) 1 I XGICIDES 

adding one quart of ammonia and mixing with fifty or 
sixty gallons of water. 

Modified Eau Celeste. Dissolve four pounds of 
sulphate of copper in ten or twelve gallons of water, 
and stir in five pounds of washing or sal soda ; dissolve 
one and one-fourth pounds of sal soda in hot water, 
then add three pints of ammonia and dilute to fifty gal- 
lons of water. 

Carbonate of Copper. This is commonly used 
in the form of an ammoniacal solution, made by dissolv- 
ing four ounces of carbonate of copper in two quarts of 
ammonia, and then adding to a barrel of water. The 
carbonate will dissolve more readily if mixed with water 
enough to form a paste before it is added to the ammo- 
nia. It is a simple fungicide, easy to make and apply, 
and as it is a clear solution there is no trouble with its 
clogging nozzles. It has been successfully used to pre- 
vent apple scab, various mildews, etc. 

Inasmuch as commercial copper carbonate is rather 
expensive, costing thirty-five to forty cents per pound 
at wholesale, Professor F. D. Chester advises that it 
be prepared at home according to the following method, 
in which case it costs, for materials, but fourteen cents 
per pound : 

"Di&solve in a barrel twenty-five pounds of copper 
sulphate in hot water. In another barrel dissolve thirty 
pounds of sal soda in hot water. Allow both solutions 
to cool, then slowly pour the solution of sal soda into 
the copper sulphate solution, stirring the same. Fill 
the barrel with water and allow the precipitate of copper 
carbonate to settle. Upon the following day siphon off 
the clear supernatant liquid, which contains most of the 
injurious sodium sulphate in solution. Fill the barrel 
again with water, and stir the precipitate vigorously 
into suspension ; again allow the precipitate to settle, 
and again on the following day siphon off the clear 



THE IMPORTANT? FUNGICIDES 19 

liquid. This operation washes the carbonate free of 
most of the sodium sulphate which contaminates it. 
Make a filter of stout muslin, by tacking the same to a 
square wooden frame which will just fit over the open 
top of the second barrel, letting the muslin hang down 
loosely so as to form a sack; through this filter the pre- 
cipitate, so as to drain off the excess of water, and as the 
filter fills remove the precipitate, and allow it to dry in 
the air, when it is ready for use. The operation is not 
troublesome, and can be carried on in connection with 
other work." 

Potassium Sulphide. Dissolve one-half ounce 
of potassium sulphide (liver of sulphur) in one gallon of 
hot water. "When cold apply in a spray. Used to pre- 
vent gooseberry mildew and similar diseases. Commer- 
cial liver of sulphur costs fifteen to twenty cents per 
pound. 

Soda Hyposulphite. Dissolve one-half ounce, or 
one ounce of soda hyposulphite in ten gallons of water. 
This is recommended by some for gooseberry mildew 
and apple scab, but it is not in general use. 

Sulphate of Copper. Besides its use in combi- 
nation with other substance, copper sulphate is often 
applied to vines and trees early in spring to destroy the 
winter spores of fungi. For this purpose it is used in a 
simple solution made by dissolving two pounds of the 
copper sulphate in fifty gallons of water. 

Copper Chloride. This is a greenish crystalline 
salt of copper, readily soluble in water, which has been 
recently tested as a fungicide at the Cornell University 
Experiment Station, with encouraging results. It is 
said to cost, at retail, about ten cents an ounce, or fifty 
cents a pound. Used at the rate of one and one-half 
ounces to twenty-two gallons of water it injured peach 
and apple foliage. So little is now known of it that no 
practical recommendations can here be made, other than 
that it is worth experimenting with. 



J>0 I (Mil AND FUN'.K tDBfl 

Sulphur. Flowers of sulphur form a valuable 
fungicide to use against various mildews and other dis- 
eases. The powder may be applied directly to the sur- 
face of the plants to be protected, or used as a wash, or 
in fumes. 

COMBINING FUNGICIDES WITH INSECTICIDES 

It is often desirable, in applying the fungicides 
used in spraying, to combine with them certain insecti- 
cides, to destroy insects attacking the crop at the same 
time. The advantages of this, in saving time and ex- 
pense, are obvious. The following two combinations 
have been found practicable : 

Bordeaux Mixture and Arsenites. Add four 
ounces of London purple or Paris green to fifty gallons 
of Bordeaux mixture. This is one of the very best 
combined insecticides and fungicides. It can be used 
safely and effectively upon a great variety of crops 
such as potatoes, for Colorado beetles and blight ; apples 
and pears, for insects and scab ; and plums and peaches, 
for curculio and leaf or fruit diseases. To use upon 
fruits the Green formula is probably the best, as too 
large an amount of copper sulphate occasionally prevents 
the perfect development of apples and pears. The 
remarks on page 16, concerning late applications of 
the Bordeaux mixture, are equally applicable to this 
combination. 

Copper Arsenic Solution. The Ohio Experi- 
ment Station recommends the following combination : 
Copper carbonate, six ounces ; Paris green, four ounces ; 
ammonia, two quarts; lime water, fifty gallons. "The 
copper carbonate and Paris green may be mixed and dis- 
solved in the ammonia (more or less ammonia will be 
required, according to the strength), after which add 
the lime water. By lime water is here meant clear lime 
water made by dissolving as much lime in water as it 



COST OF FUNGICIDE MATERIALS 21 

will take up. One- fourth of a pound of lime to a barrel 
of water is as much as is required for the purpose of pre- 
venting the injury to the foliage which the Paris green 
might cause. A convenient method is to put several 
pounds of lime in a barrel, and then fill with water; 
after stirring vigorously allow to settle, when the clear 
water may be used. The barrel may be filled with water 
each time before going to the orchard, and allowed to 
stand while gone." Only sufficient ammonia to dissolve 
the copper carbonate and Paris green should be used, 
and no more lime than directed. 

Care musb be taken in combining the arsenites with 
other fungicide solutions, as one is liable thus to pro- 
duce a compound very injurious to foliage. Paris green 
or London purple added to simple solutions of copper 
sulphate, or to ammonia compounds without lime, in- 
jures foliage vastly more than in simple water mixture. 

COST OF FUNGICIDE MATERIALS 

The approximate wholesale and retail price of the 
more important substances used for fungicides is indi- 
cated below : 

Wholesale. Kctttit. 

Perlb. Perlb. 

Ammonia (22 Ban me) $0.07 $0.20 

Carbonate of copper (Precipitated). . . .40 

Carbonate of ammonia 14 .30 

Liver of sulphur 15 .-'5 

Lime, per barrel (300 pounds) 1.65 

Soda carbonate 04 .10 

Soda hypo-sulphite 06 .15 

Sal soda 01 14 -05 

Sulphate of copper (Powdered) 07 to .09 .12 to 15 

Sulphate of copper (Crystals) 05 .10 

Sulphur 03 .10 

THE APPLICATION OF FUNGICIDES 

Fungicides may be applied to plants, either in the 
form of a dry powder or a liquid solution. In the for- 
mer case they are usually most easily handled by means 
of a powder bellows such as Leggett's powder gun 



FUNGI AND FUNGICIDES 




and in the latter by means of some form of spraying 
pump. In both cases it is important that they be finely 
divided and evenly distributed. 

There are many forms of spraying pumps upon the 
market. In general they are of four sorts : The bucket 

pumps, the knapsack 
sprayers, the barrel spray- 
ers, and the geared auto- 
matic machines. The 
form of the knapsack 
sprayer is shown in Fig. 8. 
It is useful in some cases, 
but in general the carry- 
ing of the reservoir and 
contained liquid should 
not be imposed on human 
shoulders. A convenient 
barrel outfit is shown in 
Fig. 9. The barrel has 
upon it a double discharge pump, to which are attached 
two lines of hose, provided with good nozzles, and fas- 
tened at the end to poles. Three men operate the ma- 
chine, one driving and pumping, and two directing the 
spray. 

Many different kinds of spray nozzles are also offered 
for sale. In several cases, at least, each has a peculiar 
value for certain lines of work. Consequently the fruit- 
grower who -has a variety of vines and trees to spray 
should own four or five nozzles, and use the one best 
adapted to the work in hand. Some of the best forms 
are the Improved Vermorel, Climax, Cyclone, Graduat- 
ing Spray, Mason, and Improved McGowen, No. 7. 

Professor L. H. Bailey uses, for bushes and vines 
which need to be sprayed on the under surface, the 
cyclone nozzle, in connection with a home-made wheel- 
barrow tank, as shown in Fig. 10. A piece of rubber 



FIG. 8. KNAPSACK SPRAYER. 



APPLICATION OF FUNGICIDES 26 

tubing five or six feet long connects the nozzle with the 
pump, the outer end of the tubing being tied to a light 
rod, so that the spray can be sent wherever desired. 




FIG. 9. THE CHESTER SPRAYING CART. 




FIG. 10. METHOD OF SPRAYING BUSHES. 

A fuller discussion of the subject of spraying will 
be found in the author's little manual entitled Spraying 
Crops. 



FUNGI AFFECTING ORCHARD FRUITS 



FUNGI AFFECTING THE APPLE 



The Apple Scab 

Fusicladium dendriticum 

There is, probably, no fungous disease of fruits so 
familiar to the general public as the apple scab, or, as it 
is sometimes called, the black spot. This is due to a 
fungus which produces the well- 
known scabby spots upon the 
fruit, and also attacks the leaves 
and green shoots. It first ap- 
pears upon the leaves in the 
shape of smoky greenish spots, 
more or less circular in outline. 
These gradually enlarge, and 
frequently several of them run 
together, so as to form good 
sized blotches; as they grow 
older their color darkens, finally 
becoming almost black. The 
upper surface of the leaf is usu- 
ally affected. 

FIG. 11. APPLE SCAB SPOTS Sometimes the fungus de- 
ON A LEAF. velops so rapidly on the expand- 

ing leaves in early spring as to blight them, dwarfing 
and killing the younger foliage. An instance of this, 
observed by Professor L. H. Bailey, is illustrated in 

27 




28 FUNGI AND FUNGICIDES 

Plate II, which represents the size of dwarfed leaves late 
in July, as compared with a full-grown one. In such 
seasons the newly formed fruit is also attacked by the 
fungus, which shrivels the young apples and causes 
them to fall off. Occasionally an entire crop is thus 
destroyed. 

The spores, or reproductive bodies of the fungus, 
ure produced in immense numbers on the blackened 
spots on the leaf and fruit, forming most abundantly dur- 




FIG. 12. FRUIT AXD LEAF SPOTTED BY SCAB. 

ing cool, wet weather. They are carried hither and 
thither by wind and rain. When they light upon a 
moist leaf or fruit they germinate, by sending out a 
little tube, and thus form a new center of disease. The 
spores pass the winter on the bark, twigs, and stored 
fruit, as well as on the fallen leaves and fruit. During 
the moist weather of spring they start the disease again. 
Besides the injury to the leaves and the destruction 
of the very young fruit, this disease causes serious losses 



THE APPLE SCAB 



29 



by dwarfing and disfiguring the apples that mature. 
Secretary A. C. Hammond, of the Illinois State Horti- 
cultural Society, estimated the annual loss due to this 
disease in Illinois alone at $400,000, and other authori- 
ties have estimated it at from one-sixth to one-half of 
the entire crop. 

The mycelium, or vegetative portion of the scab 
fungus, consists of brown- 
ish cells which develop 
just beneath the skin of 
the leaf or fruit, but, as a 
rule, do not penetrate 
deeply into the tissues. 
After the fungus has 
grown in this way for 
some time it pushes out- 
ward, rupturing the skin ; 
and on the exposed sur- 
face short vertical brown 
threads are developed, on 
the tips of which the 
small oval spores are pro- 
duced (Fig. 14). When FIG . 13 . SC;A BBY APPLE SHOWING 
mature the spores Sepa- RUPTUKES IN THE SKIN. 

rate, and are scattered by wind and rain in all directions. 
Treatment. In spring, just before the leaf-buds 
open, spray thoroughly with dilute Bordeaux mixture, 
or else spray before the leaf -buds begin to swell, with a 
simple solution of copper sulphate ; repeat the applica- 
tion of Bordeaux mixture a little later, just before the 
blossoms open ; spray for the third time just after the 
blossoms have fallen, adding arsenites for the codling 
moth if desired ; ten days after this third application 
spray again with the combination of Bordeaux mixture 
and Paris green or London purple. Do not apply Bor- 
deaux mixture late to early ripening apples. 




30 



FUNGI AND FUNGICIDES 



Literature. Articles concerning apple scab may 
be found in the following publications : Bulletin Ohio 
Experiment Station, IV, No. ; Report IT. S. Dept. 
Agriculture, 1887, pp. 341-347 ; First Report Wisconsin 
Experiment Station, 1884, pp. 45-56; Cornell Univer- 
sity Experiment Station, Bulletin 48. 

The Powdery Mildew 

Podosphcera oxyacanthce 

About midsummer one may often find on the leaves 
and young shoots of apple, cherry, quince, peach, and 




FIG. 14. SECTION SHOWING SCAB FUNGUS. 

A, spores in position, as developed; B, skin of fruit turned tip; C 1 , parenchyma- 
like cells of the parasite ; D I), tissues of the fruit. Much magnified. 

several other trees, small round whitish blotches of mil- 
dew, which at first have more or less of a radiated ap- 
pearance, due to the spreading of the threads. In a 
short time many of the spots enlarge so that they run 



THE POWDERY MILDEW 



31 



together ; and the mildew often covers the whole surface 
of the leaf, either as a thin coating through which the 
green surface can be seen, or as a thick, felt-like cover- 
ing, which entirely conceals the leaf surface. This mil- 
dew is composed of a great number of minute white 
threads, branching in all directions, which form the 
mycelium of the powdery mildew fungus. In the fungi 
of this group the mycelium is external, i. e., instead of 
developing on the inside of the leaf of the host-plant, it 
develops on the outside, and in order to get nourishment 




c d 

FIG. 15. APPLE POWDERY MILDEW. 

c, Mycelium formingsummerspores; c/, winter spore case (perithecium). Magnified. 
\ 

the mycelium threads send little suckers into the cells 
of the leaf and absorb their contents, for the benefit of 
the fungus. Soon after the mycelium gets well devel- 
oped it assumes a powdery appearance, due to the pro- 
duction of great numbers of the minute white spores, 
called the summer spores, or conidia (Fig. 15 V). These 
are very light, and are scattered by every breath of air. 
When one of them falls upon an unaffected leaf, where 
sufficient moisture is present, it germinates and starts 
the disease anew. By means of these summer spores a 



32 FUNGI AND FUNGICJM 

vast number of which in;iy develop from the mycelium 
of a single leaf the fungus is able to spread very rap- 
idly. Toward the end of summer the mycelium devel- 
ops small round black masses just visible to the naked 
eye, which are the cases containing the winter spores. 
These cases are technically called perithecia, and when 
magnified resemble Fig. 15, d. They remain on the 
leaves when the latter fall in autumn, and tide the fun- 
gus over winter. 

This powdery mildew may develop on either surface 
of the leaf, and is especially likely to appear on the 
^leaves and stems of young shoots. It is also usually 
much more abundant on young trees than old ones, and 
is especially destructive to nursery stock ; so much so, 
in fact, that where no treatment with fungicides takes 
place it often prevents the successful budding of a large 
proportion of the young trees. Leaves severely attacked 
by the fungus drop off prematurely, and so prevent the 
proper growth of the tree. The disease is usually most 
prevalent during seasons of dry weather. 

Treatment. As a rule, it is only in the nursery 
that this disease is sufficiently destructive to require 
remedial treatment. To prevent it, spray with the am- 
moniacal solution of copper carbonate, making the first 
application when the leaves are about half-grown, and 
repeating four or five times at intervals of twelve days. 
Mr. B. T. Galloway has shown that nursery stock can 
be sprayed with this solution five times, at a cost of 
eight cents per thousand trees, estimating the copper 
carbonate at forty cents per pound, and the ammonia 
(26) at eight cents per pound. 

Literature. An excellent general account of this 
disease, by Mr. M. B. Waite, may be found in the 1888 
Keport of the Department of Agriculture (pp. 352-357) ; 
while notices of remedial experiments appear in bulletins 
of the Division of Vegetable Pathology. 



THE BITTER KOT 33 



The Bitter Rot, Ripe Rot, or Apple Rot 

Glceosporium fructigenum 

The Bitter Rot of apples, frequently called the Ripe 
Rot, or simply the Apple Rot, is caused by a parasitic 
fungus which most commonly attacks the fruit as it 
approaches the ripening period, although it is said often 
to attack the apples tit any time after they are three- 
fourths of an inch in diam- 
eter. The injury is most 
likely first to appear at the 
calyx or blossom end of the 
fruit, but it may start any- 
where upon the surface. It 
gradually spreads from the 
point of infection through- 
out the tissues, causing 
brown and decayed spots as 
it progresses. The larger FIG. IG. APPLE AFFECTED BY BIT- 
fruits usually fall to the "L* 
ground, but many of the THE SKIN. 

smaller ones shrivel up and remain on the tree in a 
mummified condition. Great quantities of spores are 
developed on these withered "hangers-on," and by 
means of them the disease is started again the following 
spring. The fungus seems to be more destructive dur- 
ing damp weather. Professor H. Garman expresses the 
opinion that this disease causes greater loss in Kentucky 
than any other enemy of the orchardist. "It is no 
uncommon thing for three-fourths of all the fruit on a 
tree to be rendered worthless by its attacks. In the 
latter part of summer we find, in many orchards, the 
ground covered with well grown apples, suitable for mar- 
keting, as far as size and maturity are concerned, yet 
3 




34: 



I I Mil AM) FUNGICJM - 



not worth gathering up because of the rot with which 
they are wholly or in part affected." Other southern 
states suffer equally serious losses. One orchard in 
Arkansas has been reported in which, in 1887, the attack 
of the fungus was so severe that seventy-five trees yielded 
less than twenty-five bushels of fruit. A photographic 
view of one of the depressed rotten spots as it appears on 
the maturing fruit is shown in Fig. 17. 

This disease is distinguished after it lias become 
well established by the presence of small blackish PUS- 




FIG. 17. APPLE SHOWING ROT SPOT. 

tules scattered over the surface of the apple. These are 
the fruiting spots of the fungus. The mycelium which 
has penetrated the pulpy tissue of the fruit in all direc- 
tions, disorganizing it and causing the rot, here develops 
a large number of cells, which rupture the skin of the 
apple and produce the spores at the tips of slender pro- 



THE BITTEK ROT 35 

jecting threads. These spores ^ are blown off by the 
wind, or washed downward by rain. When one of them 
lodges upon another apple, where sufficient heat and 
moisture is present, it germinates by sending out a little 
tube, and may thus start the disease in a new situation. 
If the mycelium of the fungus running through the 
apple is carefully examined, one will see at frequent 
intervals on the threads small spore-like bunches, simi- 
lar to those shown in B, Fig. 19. From these other 
mycelium threads may start. In the same figure a ger- 



B 




FIG. 18. SECTION OF PUSTULE. 

A, Mass of fungus threads and cells; B, spore-bearing threads; C C, skin of apple 
ruptured by the fungus. 

minating summer spore is seen in C 9 and one of the pus- 
tules already referred to in A. 

This same fungus attacks grapes, and Dr. Halstead 
has recently found that it will develop upon pears, 
peaches, egg plants and peppers. Consequently it seems 
to have a wide range of hosts, and general clean culture 
is evidently important as a method of preventing its 
injuries. 

Treatment. The first step toward the successful 
prevention of this disease is the removal and burning of 
the mummied apples on the trees. This should be done 
during winter. It would be desirable, also, to rake up 
and burn, or bury, the fallen fruit and surrounding rub- 



3G 



l-TN<;i AND I I M.H IDKS 



bish. Then the Bordeaux mixture treatment recom- 
mended for the prevention of apple scab will have a 
decided influence in lessening the amount of damage. 

An account of experiments with this disease may be 
found in Bulletin No. 44 of the Kentucky Agricultural 
Experiment Station ; and of its nature in the 1889 report 
of the same station. It is also discussed in the 1887 
Report of the U. S. Department of Agriculture, and 
more fully in the Journal of Mycology, v. VI, p. 164. 

The Apple Rust 

Gymnosporangium and Rcestelia 

A peculiarity of many parasitic fungi is that the 
complete cycle of their existence is not passed upon a 
single host-plant, but that, instead, one phase of devel- 




FIO. 19. A, surface view of pustule; /?, mycelium thread; C, ger.ninating spore. 
Magnified. 

opment occurs upon one plant, while another quite differ- 
ent stage of existence is passed on an entirely different 
host. A striking illustration of this is seen in the case of 
the rusts which sometimes affect apple trees, causing the 
leaves to become more or less blistered with orange-yel- 
low spots. In this disease the fungus on the apple is an 
alternating form arising from spores produced by the so- 
called "cedar -apples," or "cedar-balls" of cedar or juni- 




ri,ATK ur. CEDAR APPT.KS (Oymnosporangnlm clavipes). 



38 FUNGI AND FUNGICIDES 

per. The presence of the fungus causes a peculiar 
development of the cedar leaves, as may be seen by ref- 
erence to Plate III, where a normal healthy cedar branch 
is shown at B, and a diseased one at A. The affected 
branch not only has the "apples" developed, but the 
leaves are entirely changed in shape. Reproductive 
spores are produced from these "apples;" they ger- 
minate in a way illustrated at (7, and are blown about by 
the wind. When one is carried to an apple leaf where 
conditions favorable to germination are present, it may 




FIG. 20. APPLE 1UTST. 
1, Cluster cups on under surface of leaf; 2, spores; 3, spores germinating. 

develop and produce the apple rust. The affected apple 
leaf has scurfy bunches on the under surface, the area 
on the upper surface above these becoming orange-yel- 
low, or sometimes almost crimson, in color. As the 
disease progresses the leaf becomes more and more dis- 
torted, and in case the injury affects a large proportion 
of the leaves serious damage to the tree may result. 

The spores are produced in great numbers on the 
orange-yellow areas of the apple leaf, and are blown 






THE APPLE TWIG BLIGHT 39 

away by the wind. Those which light upon red cedar, 
under favorable conditions, may develop, and by so 
doing carry the disease back to the original host plant. 
Thus there is a continual alternation of the generations 
of the fungus. 

The form of the fungus which occurs upon apples is 
commonly called the Rcestelia form. Besides the dis- 
colored areas on the upper surface of the leaf, the pecu- 
liar "cluster-cups" of the fungus are developed on the 
under surface. A group of these is represented in Fig. 
20. The "cups" are usually about a quarter of an inch 
in diameter. In them the chocolate brown spores are 
developed ; some of these are seen in 2, where the thin 
places in the wall through which the germinating tubes 
are to develop are seen at #, while in 3 some germinating 
spores are represented. 

Treatment. The knowledge of the fact that one 
essential stage of the fungus is passed upon red cedar, 
leads to the suggestion that, in a given region, the injury 
to apples may be prevented by destroying the red cedars. 
It is probable that spraying orchards with fungicides for 
scab, or other diseases, will also assist in preventing 
the rust. 

Literature. Dr. B. D. Halstead has published an 
excellent general discussion of the relations of apple 
rusts and cedar apples, in the 1888 Report of the De- 
partment of Agriculture (pp. 370-381). Professor A. B. 
Seymour has also treated of them in the Transactions of 
the American Horticultural Society (v. IV, p. 152), and 
Dr. R. Thaxter, in the 1891 Report of the Connecticut 
Experiment Station. 

The Apple Twig Blight 

Micrococcus amylovorus 

The twigs of apple trees, together with the leaves, 
flowers or fruit which they bear, often turn brown or 




Sprayed. 

PLATE IV. PEAR LEAF-BLIGHT EXPERIMENT. 



THE PEAR LEAF-BLIGHT 



41 



black, and die, in a manner similar to that of pear twigs 
affected by pear blight. Such injuries to apple are com- 
monly called "twig blight/'' or "fire blight." They 
are, however, due to the same germs as the pear blight, 
discussed on a later page under the pear. Cutting off 
and burning affected twigs is the best remedial measure. 



FUNGI AFFECTING THE PEAR 



The Pear Leaf=blight 

Entomosporium maculatum 

This is probably the most generally destructive fun- 
gous disease to which the pear is subject. It appears 
early in spring, soon after the leaves develop, usually 

revealing its presence at 
first by minute, dull red- 
dish spots on the upper sur- 
face of the leaf. A little 
later the spots appear on 
the lower surface also, and 
tho reddish tint gives way 
to brown, with a darker 
center. As the fungus de- 
velops the spots enlarge, in- 
volving more and more of 
the tissues of the leaf, until 

th6 tiSS " 6S diTCCtl affected 




FIG. 21. QUINCE LEAF SHOWING . 

LEAF-BLIGHT. within the spots, and those 

indirectly affected between, include nearly or quite the 
entire leaf, which appears sere and brown. Very young 
leaves sometimes curl up, as a result of the attack. The 
quince is also injured by this fungus, an infested leaf 
being represented in Fig. 21. When leaves are badly 




PLATE V. TEARS INJURED BY LEAF-BLIGHT FUNGUS. 



THE PEAR LEAF-BLIGHT 43 

injured they fall off, and whole orchards are some times 
defoliated by the disease, the trees appearing as bare in 
midsummer as they normally do in winter (Plate IV, 
unsprayed). Of course, the effect upon the tree is very 
injurious; it is unable to store up the materials of 
growth properly, and it becomes weak and impoverished. 
But this fungus does not confine its attention to 
the foliage ; the stems and fruit are also attacked. The 
former become blackish and dead, and the latter is at 
first covered with reddish pimples, which finally become 
blackened and roughened, and generally cause the pear 
to crack open in such a manner as to ruin the fruit. 
Several such pears, photographed by Dr. 11. H. Lamson, 
are represented in Plate V. 

This disease is especially destructive to young pear 
trees in the nursery, and the defoliation caused by it 
quite generally prevents successful budding, unless pre- 
ventive treatment is given. A good general account of 
the fungus occurs in the 1888 report of the Department 
of Agriculture. 

The little black dots in the centers of the spots con- 
sist of the fruit of the fungus. If a vertical section be 
made of one of these and it be placed under the micro- 
scope, it will be seen that the pecu- 
liar two- to six-celled spores shown in 
Fig. 21 are borne upon short stalks 
coming from the mycelium in the 
leaf cells. These spores germinate 
under favorable conditions, sending 
out a tube which burrows its way 
into the tissues of the leaf, and starts 
the fungus again. These spores are 
the conidia, or summer spores. Other 
MAGNIFIED. spores the so-called winter spores 
are said, by some botanists, to be found among the 
fallen leaves. 




44 FUNGI AND l-TN<;i< I 1*1 ~ 

Treatment. Sprjiy with the aramoniacal solution 
of carbonate of copper as soon ae leaves !>r^in to unfold. 
and repeat application two or three times at interval- of 
two weeks; or the dilute Bordeaux mixture may he 
used, spraying in the same manner as recommended for 
apple scab. The effect of treatment with the Bordeaux 
mixture, as shown in one of Mr. Galloway's experiments, 
is illustrated in Plate IV. Discontinue the treatment 
before the fruit is half grown. 

The Pear Blight 

Micrococcus amylovorus 

The literature of American horticulture during the 
present century contains frequent references to the per- 
plexing malady called pear blight. Until recently there 
were innumerable theories as to the cause and cure of 
the disease ; but now, thanks to the investigations of 
Professors Burrill and Arthur, we know that it is due to 
the presence of a specific germ one of the bacteria so 
minute as to require the aid of a powerful microscope to 
sec it. 

Pear blight is easily distinguished from other mala- 
dies. Limbs affected by it become dead and blackened, 
together with the leaves, flowers or fruit which they 
bear. The injury may be confined to one or a few limbs, 
or may gradually extend to the whole tree. The twigs 
of apples and certain other pomaceous fruits are also 
liable to the disease. 

The germs of pear blight are so minute that they 
are carried through the air by the slightest wind. They 
seem to be unable to penetrate healthy bark, but gain 
access to the interior of the tree through the blossoms. 
They light upon the sticky surface of the inside of the 
flower cup, and are able to begin developing there, pass- 
ing down through the stem to the twig below. The 



THE PEAR BLIGHT j 

germs can also gain access through the tips of growing 
branches where the green growth is soft and succulent, 
and, no doubt, they occasionally enter through cracks 
in the bark. 

After the bacteria have gained access to the tissues 
of the tree they multiply rapidly, and generally in the 
course of a few weeks have become so abundant as to 
show their presence by blackening the bark or blossoms. 
"As the disease progresses," says Professor Arthur, 
"the germs exude on the surface, and the gummy sub- 
stance thus produced is washed off ; the gum is dissolved 
and the germs set free and washed into the ground. 
The germs multiply there in rich mold and grow all 
winter, or year after year. In a dry time the wind takes 
up the germs into the air, or they may be taken up by 
simple evaporation. Xow when the surface of the tis- 
sues is tender and moist, as in spring, the air, laden 
with these germs, playing over the trees, brings the 
germs in contact with the delicate tissues. The germs 
are held there by the moisture and enabled to grow ; the 
disease gets a foothold, and in the course of a month or 
two it shows itself by the sudden blackening of the 
leaves." Insects also carry the germs to blossoms. 

Treatment. No successful method of preventing 
the disease by artificial applications to the trees has yet 
been found. But it has been shown that if the trees are 
carefully watched during the season of growth, and the 
affected twigs cut off (at least a foot below the lowest 
point of injury) and burned, the damage done may be 
greatly lessened. Professor Burrill advises the examina- 
tion of the trees once a fortnight, and states that the 
bark reveals the damage best after a shower, when the 
surface is wet. It is important, also, to keep the bark 
free from wounds. 

The fact that slow growing pear trees are less liable 
to injury by blight than those of rapid growth has long 



46 FUNGI AND FUNGICIDES 

been noticed. Consequently, such cultural methods as 
will tend to produce a slow, steady growth are to be 
adopted. 

Literature. The really valuable publications con- 
cerning pear blight date from Professor Burrill's an- 
nouncement of the genuine cause in 1880. His articles 
may be found in the following publications : Transac- 
tions Illinois State Horticultural Society, 1880, pp. 157- 
167 ; 1883, pp. 46-49 ; Report American Pomological 
Society, 1880; Report Trustees Illinois Industrial Uni- 
versity, 1880 ; Transactions Illinois Department of Ag- 
riculture, 1880, pp. 433-436. Professor J. 0. Arthur 
has also published a number of valuable papers. A sum- 
mary of his results may be found in the Report U. S. 
Department of Agriculture, 1886, .pp. 125-129; Report 
of the American Pomological Society, 1885 ; and Report 
of the Michigan Horticultural Society, 1885, pp. 173-177. 
More recently Mr. M. B. Waite has been investigating 
the disease. His results may be looked for in the publi- 
cations of the Division of Vegetable Pathology. 

The Pear Scab 

Fusicladium pyrinum 

This disease is very similar to apple scab, the fun- 
gus, in fact, being believed by many botanists to be the 
same species. At any rate, the chief points in the life- 
history and remedial treatment are the same as for the 
apple disease. 

Care should be taken not to apply the Bordeaux 
mixture too late in the season. Early varieties should 
have but one spraying with this mixture after the fruit 
ff sets," and late varieties but two. Where additional 
applications are needed, use the copper carbonate solution. 



FUNGI AFFECTING THE QUINCE 



The Leaf=blight and Fruit=spot 

Entomosporium maculatum 

The leaves of quinces often become dotted with 
small round brown spots, resembling Fig. 23, which 
gradually become more numerous, 
and may finally run together to 
form large blotches, as shown in 
Fig. 21 (p. 41), involving, occa- 
sionally, the whole leaf, and caus- 
ing the premature dropping of 
the foliage. This is the same 
fungus that causes the leaf-blight 
of the pear, and the main points 
in its development have already 
been described (pp. 41-44). 
Quince fruit, as well as foliage, is 
attacked by it, the effect on the 
FIG. 23. QUINCE LEAF-BLIGHT f ru jfc k e i n g see n in small brown, 
or blackish spots which appear on the surface, and have 
given the disease the name of fruit-spot. Several of 
these spots frequently run together, and sometimes a 
large part of the surface becomes affected. The fungus 
dwarfs the fruit, and renders it less salable. The defo- 
liation of the trees, of course, greatly reduces their 
vitality. Young quince trees in the nursery are espe- 
cially liable to injury by this disease, as it causes the 

47 




FUNGI AND FUNMi tDB 



leaves to fall off during summer, and so prevents t In- 
growth necessary for successful grafting. 

Treatment. The treatment recommended for the 
pear (p. 44) is equally applicable to this fruit. The 
benefits of spraying with the Bordeaux mixture were 




FIG. 24. YOUNG QUINCES INJURED BY RUST. 

illustrated in a striking manner, by the results of some 
experiments made at the Connecticut Agricultural Exper- 
iment Station by Dr. Roland Thaxter. The sprayed rows 
had been treated both that season and the previous one, 
and so the year before had had an opportunity to store up 



THE QT1XCE KUST 



49 



nourishment for fruit production. Three applications 
were made, the first May 11, the second May 28, and 
the third June 22. Two sprayed rows yielded seventy- 
one and one-half baskets of marketable fruit, while five 
untreated rows yielded one basket of marketable fruit. 
"Comparing the yield from the untreated rows, and 
estimating it at one-third basket per row, which is more 
than was actually obtained, the net income from a single 
treated row was one hundred times as great as from an 
untreated row." 

The Quince Rust 

RoRstelia aurantiaca 

Young quinces are sometimes disfigured by the 
presence of a rust fungus, in the peculiar way repre- 
sented in Fig. 24. On some por- 
tion of the distorted surface orange 
spots eventually appear; they are 
usually more or less elevated. From 
them the spores of the fungus are 
produced in immense numbers, to 
be borne hither and thither by the 
wind. A peculiar fact concerning 
these spores is that they do not de- 
velop on the leaves and fruit of 
other quinces, but, instead, are 
only able to develop upon the 
branches of red cedar and low jun- 
iper. Those spores which are 
blown to these plants under favor- 
able conditions, produce on them the "cedar balls," or 
"cedar apples," so often noticed. One of these is repre- 
sented in Fig. 25. On the cedar or juniper other spores 
are produced, for the wind to carry back to quince to 
start the rust again. Thus there is constantly what is 




FIG. 25. CEDAR BALL. 



50 FUNGI AND PUHG1I tDEfl 

known as an alternation of the grin-rations of the fun- 
gus, and two entirely different plants arc rc<|iiind for 
its continued growth. 

This rust is very similar to that which occurs upon 
the apple, discussed on a previous page. One important 
preventive measure consists in the destruction of cedars 
and junipers ; and, probably, spraying with fungicides 
will prove to be another. 

The Black Rot 

Sphceropsis malorum 

The fruit of the quince is subject to injury by sev- 
eral fungi which cause rot. The ripe rot of apples due 
to Glceosporium fructigenum often attacks them ; a 
species of Phoma causes what has been called the "pale 
rot," and other fungi occasionally induce decay. The 
most destructive of these fruit diseases, however, is the 
black rot, which usually first appears upon the fruit 
when it is half grown, or larger, in the guise of a small 
brownish spot on the surface, generally at the blossom 
end. The spot increases in size rapidly, and blackish 
pimples soon appear; later the skin ruptures at these 
pimples, and the spores of the fungus escape, to be dis- 
tributed by the wind. The infested fruit often becomes 
mummified, and may remain on the bushes over winter. 
This fungus also attacks apple and other pomaceous 
fruits. Quince orchards in the vicinity of apple or pear 
trees are liable to infestation from them, and vice versa. 

While it is probable that the use of fungicides will 
prevent this disease, it usually appears so near the time 
of harvest that their application may not be advisable. 
Diseases of this kind may be prevented, to a considerable 
extent, at least, by clean culture, the destruction of 
the rotting or mummified fruits, by means of which the 
disease is propagated. This may often be supplemented 



THE TWIG BLIGHT 51 

to advantage by comparatively late spraying with the 
ammoniacal solution of copper carbonate. 

An illustrated account of this and other quince fruit 
rots will be found in Bulletin 91 of the New Jersey Ex- 
periment Station. 

The Twig Blight 

Micrococcus amylovorus 

Quinces are sometimes attacked by the "fire blight," 
or "blight" of tbe pear, discussed on Pages 44 to 46. 
Branches so attacked turn black and are easily distin- 
guished. Cutting and burning, as recommended for 
the pear, are the best remedial measures. 




PLATE VI. BRANCHES OF YOUNG PLUM TREE AFFECTED BY BLACK 

KNOT. 



FUNGI AFFECTING THE PLUM 



The Black Knot 

Plowrightia morbosa 

No fungous disease of fruits is easier to recognize 
than this; the black, wart-like excrescences upon the 
twigs and branches of plum and cherry trees are too 
well known to the majority of fruit growers. In many 
of the older settled portions of the country the disease 
prevails to such an extent, that it has led to the practi- 
cal abandonment of the culture of these fruits; and a 
similar condition is threatened in other localities unless 
preventive measures are vigorously applied. The fun- 
gas attacks nearly all varieties of wild and cultivated 
plums, and most varieties of cherries. 

During the earlier years of the present century there 
was much discussion concerning the cause of black knot. 
Some horticulturists contended that it was due to in- 
sects ; some that it was a constitutional affection of the 
trees ; and some that it was due to fungi. The latter 
proved the correct supposition, the life-history of the 
fungus having been first worked out in 1875 by Dr. 
W. G. Farlow. Like other fungi, this one reproduces 
by means of spores. The knots first appear as swollen 
places on the twigs ; as the swelling increases the bark 
cracks open longitudinally, and the fungus produces 
quantities of spores within these cracks, making them 
appear as if covered with a velvety olive coating. These 
are the summer spores ; they are blown through the air 
by wind, and washed from twig to twig by rain ; those 

53 



54 



FUNGI AND FUNGK I 




FIG. 26. SPORES OF BROWN ROT. 
MAGNIFIED. 



that lodge upon the tender bark of young shoots send 
out germinating tubes and start other knots. 

"As the season advances," says Dr. Halsted, "the 
young knots and the fresh growth of older ones lose 
their olive, velvety appearance, turn a dark color, and 

develop a hard incrusta- 
tion on the surface. AVi th- 
in the substance of this 
black and brittle layer 
many spherical pits are 
formed, and, as winter 
advances, minute sacs are 
produced upon the wall of 
the cavity, that toward 
spring bear each eight 
oval bodies that are known 
as sac spores. These 
escape from their long 
sacs and pass out through a pore at the top of the cav- 
ity, and are then carried by the winds to the surface of 
a young cherry or plum 
twig, and thus begin 
another knot, which, in 
the course of time, pro- 
duces a new crop of sum- 
mer, and another of winter 
spores, and thus the dis- 
ease is preserved and 
propagated." 

Treatment. The only 
successful treatment for a badly infested tree is to cut 
and burn it, trunk, branch and all. All knots on trees 
but little affected should be cut and burned. Never 
throw the removed knots on the ground, as spores are 
developed off as well as on the tree. When young 
knots appear on large limbs, or on limbs that one does 





FIG. 27. BROWN ROT SPORES GER- 



THE BLACK KNOT 55 

not wish to remove, it is believed that painting them 
with a mixture of red oxide of iron in linseed oil will 
destroy them. Probably an application of the Bordeaux 
mixture would prove equally effective. All trees liable 
to injury by this disease should be examined at frequent 
intervals, and any signs of forming knots be at once 
removed. 

Concerted action is necessary among all the fruit 
growers of a neighborhood, if the disease is to be stamped 
out. Local horticultural societies should agitate the 
matter and create a public opinion that will render it 




FIG. 28. PLUMS AFFECTED BY IJROWN ROT. 

uncomfortable for any one to allow the knots to remain 
on his trees as a source of contamination for his neigh- 
bors' orchards. In some states laws have been enacted 
compelling the destruction of the knots. Wild cherry 
trees should be included in the examination for diseased 
trees. 

Literature. Dr.^Farlow's article was published 
about 1875, in the Bulletin of the Bussy Institute. An 



FUNGI AND FUNGICIDES 



excellent popular account of the disease, by Dr. Hal- 
sted, appears in Bulletin 78 of the New Jersey Experi- 
ment Station. There are many other short accounts 
scattered through our horticultural literature. 

The Brown Rot 

Monilia fructigena 

The brown rot of stone fruits is probably familiar to 
every grower of plums, peaches or cherries in the older 
portions of the United 
States. It is one of the 
most destructive fungous 
diseases of fruits, attack- 
ing not only the fruit 
itself, but also the twigs, 
leaves and blossoms. It 
is occasionally found upon 
the apple and pear, but in 
the Northern States is 
seldom destructive to 
these fruits, although in , Chains of spores; 6, branching mycelium. 

some southern localities it is reported to do serious dam- 
age. The annual cycle of the fungus of brown rot may 
be briefly outlined as follows, starting with its attack 
upon the fruit : A minute spore (Fig. 26) falls upon a 
green plum on which there is a little water, left by rain 
or dew, and sends out a germinating tube which pene- 
trates the skin of the fruit. Once inside it grows rap- 
idly, pushing its branches through the pulp in all direc- 
tions, and thus forming a dense mass of mycelium, 
which absorbs the contents of the cells, disorganizing 
the tissues and causing the so-called rot. The affected 
plum at first turns brown in one or two spots; these 
gradually enlarge until, finally, thje whole plum becomes 
brown and "rotten." When it has reached this stage it 




BROWN ROT. MAGNIFIED. 



THE BROWN ROT 



57 



soon becomes covered with a brownish, or ash-colored 
velvety coating, which consists of vast numbers of mi- 
nute spores produced by the mycelium of the fungus. 
If one of these velvety masses be shaken over a glass 
" slide," and the slide be put under the microscope, it 
will be seen that a great many of the spores have sepa- 
rated and fallen off, as shown in Fig. 26. The spores 
are blown about by the wind, and when one of them 
lodges on an unaffected plum where sufficient moisture is 




FIG. 30. MUMM1KI) PLUMS. 

present it starts the disease again. The rotten plums 
continue hanging upon the tree, gradually shriveling up 
(Fig. 28), until . finally they become dry and mummied 
husks, roughened by ridges of the skin, and in this state 
they remain on the trees through the winter (Fig. 30). 
On many of these mummied plums some spores will 
adhere, even until the following spring, when they ap- 
parently have the power of germinating ; and in all, or 
nearly all, of them the mycelium remains in a dormant 



58 FUNGI AND FUNGICIDES 

condition, so that during the warm, damp weather of 
early spring this mycelium is able to produce u new crop 
of spores. These spores are scattered everywhere, and 
many of them develop in the blossoms and young It, 
Serious losses are sometimes occasioned by this kind of 
injury to the blossoms. As soon as the fruit is well 
formed it also may be attacked. 

Treatment. The first essential to success in pre- 
venting this disease is to pick oif and burn, as early in 
winter as possible, all mummied plums hanging upon the 
frees ; and the spraying treatment recommended below 
should also be supplemented by an occasional inspection 
of the bearing trees, and the removal and burning of 
such rotting plums as may be seen. The most success- 
ful results so far obtained in spraying for this disease, 
have followed the use of the dilute Bordeaux mixture 
and the ammoniacal solution of carbonate of copper, 
especially the former. Spray first before the blossoms 
open ; then as soon as the fruit is well formed spray 
again, and repeat the application twice later at intervals 
of two weeks. If the Bordeaux mixture is used, Paris 
green may be added for the earlier sprayings, to destroy 
the curculio at the same time. 

Literature. One of the first general accounts of 
this disease w r as published in 1885, by Professor J. C. 
Arthur, in the Fourth Eeport of the New York Agri- 
cultural Experiment Station. This was followed, in 
1888, by an extended article, illustrated by two excellent 
plates, by Mr. B. T. Galloway, in the Report of the 
United States Department of Agriculture for that year 
(p. 349-352) ; and since then Dr. Erwin F. Smith has 
contributed to the Journal of Mycology (v. Y, p. 123 ; 
v. VII, p. 36) some valuable additional information. 
Professor J. E. Humphrey has also published a popular 
account of the disease in the Eighth Report of the Massa- 
chusetts Agricultural Experiment Station. 




LATi: VI. I'M'M POCKETS. 



60 FUNGI AND FUNGICIDES 

Plum Pockets 

Taphrina pruni 

Although this remarkable disease has been known 
for many years (having, indeed, been described as early 
as 1593), its real cause has been recognized only compar- 
atively recently. It was formerly supposed to result 
from the attacks of insects, or from improper fertiliza- 
tion of the ovule ; but it is now known to be due to the 
growth of a fungus. 

Mr. Galloway states that "the 'pockets' (Plate VI) 
make their appearance soon after the flowers have fallen, 
attain full size and drop from the trees toward the mid- 
dle or last of June. At first they are more or less glob- 
ular in shape, but as they grow older they become 
oblong, or oval, and frequently more or less curved. 
They vary in size, but, as a rule, are from one to two 
inches in length, and from one-half to one inch in diam- 
eter. When young they are nearly smooth, and can be 
distinguished from the healthy fruit by their pale yellow 
or reddish color. As they grow older the color changes 
to gray, the surface appearing as though it had been 
sprinkled with fine powder, and at the same time the 
pockets become " wrinkled. Finally they turn black, or 
dark brown, and rattle like bladders when brought in 
contact with any hard substance. They remain on the 
tree in this condition for two or three days, then fall to 
the ground and perish. Sections through the diseased 
fruit show that the walls are quite thick, and that in 
place of a stone there is a large cavity filled with fun- 
gous threads and air." 

The leaves and young branches are also sometimes 
attacked by the fungus; both become swollen and dis- 
torted. When a tree once begins to bear the pockets it 
usually continues bearing them during following seasons, 
unless vigorously pruned. The red and purple varieties 



PLUM POCKETS 



61 



are the ones most often attacked, but all kinds are liable 
to injury ; and the fungus is occasionally found upon 
wild cherries. 

The mycelium of this fungus consists of numerous 
colorless threads which ramify through the tissues of 
the young fruit. A special development of these threads 
occurs just beneath the outer skin (cuticle), and from 
this there are sent upward numbers of short cylindrical 
bodies (Fig. 31 ), which finally burst through the skin 
and grow till quite long, as seen at I, being filled with a 




TfWt 



FIG. 31. PLUM POOKKT FUNGUS. MAGNIFIED. 

granular matter. Then a transverse partition is pro- 
duced a short distance from the upper end, and the 
granular matter gathers itself together in six or eight 
little spores (c). These spores finally escape from the 
cell in which they are held, and, under favorable condi- 
tions, germinate. In so doing each of the spores pro- 
duces on one side a bud having a shape similar to the 
spore itself; this bud produces another bud, and this 
another, until the substance of the original spore is 
exhausted. But botanists have not yet been able to 
infect healthy plums with these spores or their buds. 



ii \i;i AND i i N(,K IDI:S 



The mycelium of the fungus also winters over in the 
tips of the young branches. 

Treatment. A vigorous pruning of all affected 
branches some distance from the tips, in order to remove 
the mycelium in the tissues, seems to be the most prac- 
ticable remedial measure. The pockets should, of 
course, be removed before maturing, and the safest way 
will be to burn all the material so cut off. 

Literature. The best article upon this subject so 
far, published in America, occurs in the United States 
Department of Agriculture Report for 1888 (pp. 
3G6-369). 

The Plum Fruit-scab 

Cladosporium carpophilum 

In Iowa and some other localities a comparatively 
little known disease has recently been noticed on native 





ripening, in the 



d 

FIG. 32. PLUM DISEASES, 
a, 6, Fruit scab; c, fruit spot. 

plums. It appears when the fruit is 
shape of minute round specks, of a paler or grayer color 
than the surrounding skin. These usually enlarge as 
the fruit ripens, finally attaining a diameter of a quarter, 
or even half an inch. Several spots sometimes run 
together to form a blotch. The mycelium of the fungus 



THE PLUM LEAF-BLIGHT 63 

does not penetrate deeply into the fruit, and in itself 
the disease visually causes little direct damage ; but indi- 
rectly it is often injurious, by making cracks in the skin 
through which the spores of other fungi get entrance to 
the pulp of the fruit. Presumably spraying with Bor- 
deaux mixture will have a preventive effect upon it. 

THE PLUM FEU1T-SPOT 

Professor L. H. Bailey has called attention to a 
fruit spot affecting certain native varieties of plums in 
the south (Fig. 32 c). It is caused by a species of 
Phoma, and is believed to be allied to the black rot of 
the grape, and to be controlled by the Bordeaux mixture. 

The Plum Leaf=blight 

Cylindrosporium padi 

The leaves of plum and cherry trees are often at- 
tacked by a fungus which produces a blight that some- 
times becomes very destructive, causing whole orchards 
to drop their foliage prematurely, and thus interfering 
with the normal development of the trees. Small dis- 
colored spots, generally of a purplish hue, are the first 
indications shown by the leaves, of the attack. In a 
short time these spots turn brown, the tissues being 
destroyed, and later the leaves become yellow, while 
many of the affected areas separate from the surround- 
ing portion of the leaf and drop to the ground, leaving 
holes, which have given the disease the name of "shot- 
hole fungus." It is also called the leaf-spot disease. 
Under a lens the brown spots show a few black dots, 
where the reproductive spores are developing. The 
fungus is believed to live over winter on and in the 
fallen leaves. 

Some confusion exists in horticultural and myco- 
logical literature concerning the nomenclature of this 



64 



FUNGI AND FUNGICJM 



disease. Various names of fungi have been used in 
connection with it, one of the commonest being Seploria 
cerasina. The name printed above is the <nr now 
accepted by botanists. 

The leaf-blight is especially destructive in the nur- 
sery, the young trees often 
being defoliated before the 
middle of August. Bear- 
ing plum trees also lose 
their leaves prematurely 
on account of it. 

Treatment. Exper- 
iments conducted on an 
extensive scale by the Ohio 
Experiment Station show 
that in the orchard this 
disease may be prevented 
by spraying with dilute 
Bordeaux mixture. Two 
or three sprayings early in 
the season are deemed suffi- 
cient. It should not be 
used too late, on account 
of the liability of the mix- 
ture to remain on the 
ripened fruit. In the nur- 
sery the Bordeaux mixture 
is also a preventive ; the 
results of its use are well 
represented in Fig. 34, re- 
duced from photographic FIG - 
views of experiments conducted by the Division of 
Vegetable Pathology. 

Literature. This disease has frequently been dis- 
cussed in our horticultural literature, although very 
little of value concerning remedies has been published 




PLUM LEAF. 



THE PLUM LEAF-RUST 



65 



until quite recently. An account of the Ohio experiments 
mentioned above will be found in the Bulletin of the 
Ohio Experiment Station for December, 1891 (v. IV, 
pp. 216-217), and of the nursery experiments in the 
Journal of Mycology (v. VII, No. 3). 




FIG. 34. SPRAYIJSTG FOR PLUM LEAF-BLIGHT. 

The Plum Leaf=rust 

Puccinia pruni-spinoscB 

This is a disease somewhat similar to the last. 
Leaves affected by it become spotted with reddish above, 
and yellowish-brown below, and when the attack is se- 
vere the trees may be defoliated. The remedial treat- 
ment is the same as for the leaf-blight. 
5 



FUNGI AFFECTING THE CHERRY 



The Brown Rot 

Monilia fructigena 

As stated on page 56, where this disease is discussed 
in its relations to the plum, 
it frequently attacks cher- 
ries, as well as plums and 
peaches. Its life-history on 
the cherry does not differ 
materially from that on the 
plum, although it usually 
does not pass from fruit to 
fruit so often on the cherry, 
because the individual fruits 
do not touch each other so 
much. Fig. 35 represents a 
sound ripe cherry, together 
with one mummified by this 
disease. 

FIG. 35. DISEASED AND SOUND 




GHEBBY. 



The Black Knot 

Plawrightia morbosa 

This disease is often as destructive to cherries as to 
plums, under which it has already been discussed 
(pp. 53-55). The account of its life-history and the 
means of exterminating it there given applies with equal 
force when it affects the present fruit. 

The fungus which causes plum leaf-blight also 
attacks the cherry, and frequently does great injury. 

66 



FUNGI AFFECTING THE PEACH 



The Peach Leaf=curl 

Taphrina deformans 

It often happens that in spring, soon after the 
leaves begin to expand, the foliage of peach trees be- 
comes curled and misshapen. The 
leaves are usually thickened and 
discolored, and fall off in a short 
time. All the branches may be 
attacked, or the injury may be 
confined to only a part of the tree. 
When the disease is severe the 
young fruits fall off, and the crop 
for the year is destroyed. The 
defoliated trees soon push out a 
new set of leaves, but too late to 
repair the damage done to the 
fruit crop. 

This, leaf -curl is most injuri- 
ous during wet springs. It often 
rnins the peach crop over large 
areas. It is uncertain in its 
attacks, and comparatively little 
is known of the life-history of the 
fungus which causes it. 

If a thin section of one of the 
swollen leaves be placed under a 
high power of the microscope, the 
FIG. 36. PEACH LEAF-CURL, threads of the mycelium of the 
fungus can be seen between the leaf cells, and sometimes 
extending through them. The mycelium is most abund- 

67 




68 FUNGI AND FUNGICIM- 

ant just beneath the outer skin, and it pii-ln-s out 
through the skin numerous "spore-sacs," each continu- 
ing a half dozen or more spores. These spiv> ;nv -up- 
posed to spread the disease to other peach leaves but as 
stated above, very little is known of the life-history of 
this fungus. 

Treatment. No practical remedy for this di 
lias yet been found. The removal and burning of dis- 
eased leaves, whether on the tree or ground, is commonly 
recommended ; and spraying the trees early in spring, 
before the leaves expand, with some of the fungicides, 
has been suggested. The latter method is worthy of 
trial. 

Literature. The peach leaf-curl is very frequently 
mentioned in our horticultural literature, but few im- 
portant articles concerning it have been published. The 
best popular discussion that has come to my notice is in 
Professor Lamson-Scribner's excellent little volume on 
the "Fungus Diseases of the Grape and Other Plants" 
(pp. 126-131). 

The Peach Yellows 

The peculiar affection of peach trees called the 
"yellows," has been known to occur in America for at 
least a century, and during that time it has ravaged 
many of the fairest orchards of the country. Although 
most commonly affecting peaches, it also occurs in nec- 
tarines, almonds and apricots. 

No disease of fruits has proved so difficult to investi- 
gate as this. Until very recently there were numberless 
theories as to its cause, but the investigations of Dr. 
Erwin F. Smith, to whom we are indebted for much of 
the positive knowledge now possessed concerning it, 
indicate that it is a germ disease, due, probably, to some 
obscure bacterium-like organism. 



70 



FUNGI AND FUNGICIDES 



Peach yellows now occurs over a large portion of 
the States east of the Mississippi River. During recent 
years it has destroyed thousands of trees in Michigan, 
Maryland, Delaware, New Jersey and New York. 

Symptoms. According to Dr. Smith, "the earli- 
est unmistakable symptom of the yellows is the prema- 
ture ripening of the fruit. Diseased trees ripen their 
fruit, in whole or in part, from a few days to several 
weeks in advance of the proper time. Often the peaches 
on one or two limbs only will be diseased, all the rest 
ripening in a normal manner. In such cases the prema- 
ture peaches are full-grown, ripe, and high colored, 
when those on the rest of the tree are green and but half 
grown. These peaches, no matter what their natural 
color, are more or less red and purple spotted on the 
skin, and splashed and streaked within. Sometimes 
the normally white or yellow flesh is very beautifully 
mottled, or almost entirely crimson ; again there is 
hardly a trace of the abnormal color. The flavor of 
immature peaches varies considerably, but they are usu- 
ally insipid, and sometimes bitter. 

"The next symptom, which generally appears the 
same season, but is sometimes delayed until the next, is 
the appearance of diseased, dwarfed growths upon the 
trunk and limbs. These growths bear diminutive leaves, 
which are pale green, yellowish, reddish or white. They 
often show a marked tendency to repeated branching, 
sometimes as many as four sets of branches being devel- 
oped within a few months. These growths may arise 
either from obscure buds on the trunk and main limbs, 
or from the ordinary winter buds. They may appear at 
any time during the season, from spring until late au- 
tumn. Often the winter buds push in October or No- 
vember, after the foliage has fallen, or even in August 
and September, while it is still green and vigorous. 

" When attacked the tree is very often in a vigorous, 
healthy looking condition, and sometimes during the 



THE PEACH YELLOWS 



71 



whole of the first season there is no sign of disease be- 
yond the appearance of a few premature peaches, the 
foliage being fully grown and dark green, and the shoots 
in no way dwarfed or sickly. As already intimated,, the 




FIG. 37. YELLOWS TUFT. 



disease usually appears first in one limb or one side of 
the tree, but sometimes in all parts of the tree at once, 
or on opposite sides. No matter to how slight an extent 
the tree is first diseased, it never recovers, but becomes 



73 FUNGI AND FUNGICIDES 

entirely diseased in the course of two seasons, or at 
most, three. 

"The limbs first attacked are badly diseased the 
second year, their entire growth, shoots and foliage, 
being much dwartVd and of a sickly green, tinged with 
yellow or reddish-brown. In course of two or three sea- 
sons the entire growth of the tree assumes this appear- 
ance, and is then a sufficient warrant for the common 
name, such trees especially, when massed in orchards, 
being distinguishable at some distance by their yellow 
or reddish-brown appearance, which is in marked con- 
trast with the beautiful dark green of healthy foliage. 

" Trees not infrequently die outright the second 
year of attack, but ordinarily they languish for a num- 
ber of years, dying gradually from the extremities down- 
ward. Often such trees are barren after the first year, 
or they may bear another crop of premature peaches, 
which are, however, of small size and very inferior 
flavor." 

An orchard ruined by yellows is represented in 
Plate VII, while in Fig. 37 is shown a tuft of diseased 
twigs. 

Treatment. No remedy for this disease is known. 
The only successful treatment yet found is that of 
promptly digging out and burning all affected trees. 
In several States this is made compulsory by special 
laws, and in Michigan, at least, it has proven quite a 
satisfactory method of stamping out the disease. 

Literature. A very elaborate report upon the 
peach yellows, prepared by Dr. Erwin F. Smith, was 
published in 1888, as Bulletin No. 9 of the Botanical 
Division of the United States Department of Agricul- 
ture. A short summary of the same results was also 
published in the Department Report for the same year 
(pp. 393-398). Since then Dr. Smith has published 
various reports of progress in the publications of the 



THE PEA.CH ROT 73 

Department and elsewhere, especially in Bulletin 1 of 
the Division of Vegetable Pathology. 

The Peach Rosette 

The name Peach Rosette has been given to an ob- 
scure disease affecting trees in various States, character- 
ized by the presence of rosettes of leaves upon the 
branches. It has been studied by Dr. Smith in connec- 
tion with peach yellows, and is treated of in the publi- 
cations referred to above, especially in the Journal of 
Mycology (v. VI, No. 4). 

The Peach Rot 

Manilla fructigena 

The main points in the development of this fungus 
have already been discussed under the plum (pp. 56-58). 
It also attacks peaches, and probably causes more loss 
on this fruit than on the other. Dr. E. F. Smith, who 
has made a special study of peach enemies, says : " This 
fungus is more common and far more destructive than 
any other observed on the peach in this country. It is 
rarely absent from the orchard, and in rainy weather it 
frequently destroys from one-half to three-fourths of the 
crop, in some cases the entire crop. Under its influence 
the fruit quickly loses its normal color and flavor, and 
becomes an entire loss to the grower. As the fungus 
invades the healthy tissues of the fruit the latter become 
leather-colored, or dark brown, and the peach is said to 
rot, although, as Yon Thiimen first pointed out, the 
change is not strictly a 'rot.'" 

During unusually wet springs the blossoms of peach 
trees are frequently destroyed by this fungus, and the 
young twigs are also attacked. The spores are propa- 
gated in vast numbers by the mummied peaches hanging 
on the trees, and are blown through the orchard, carry- 




PLATE VIII. PEACH BLOSSOMS BLIGHTED BY ROT FUNGUS. 



THE PEACH ROT 75 

ing destruction wherever they light on a blossom. This 
injury is sometimes called "peach blight." Some blos- 
soms so injured are represented at the right in Plate VIII, 
from a drawing published by Professor F. D. Chester. 
Some tufts of spores on a twig are shown at the left of 
the same figure. 

Treatment. The remarks upon this subject con- 
cerning the plum (p. 58) are equally applicable to the 
peach. Experiments made in Delaware indicate that a 
considerable proportion of the rot may be prevented by 
proper treatment. Professor Chester recommends the 
following procedure : Pick off late in autumn or early 
in winter all mummied fruit on the trees. It would be 
better to remove it at the time of picking, or soon after. 
Spray with simple solution copper sulphate (one pound 
to twenty-five gallons water) early in spring before fruit 
buds begin to swell. Spray again with ammoniacal so- 
lution copper carbonate as soon as these buds begin to 
swell, and repeat the application just before the buds 
open, to prevent injury to blossoms. "As soon as the 
fruit shall have reached full size and begins to show 
signs of color, make a third application. This should 
be followed by two or three other applications at close 
intervals of five or seven days during the ripening period. 
A heavy rain followed by warm weather may, at this 
vital period, cause the peaches to rot rapidly ; hence, 
due regard should be given this point in regulating the 
exact time when a spraying should be made. Due atten- 
tion to this principle may save hundreds of baskets of 
fruit, and the grower can well afford to make spraying 
at the right time his first business." It may be doubted, 
however, whether these late applications are advisable, 
from a sanitary standpoint. Treatment with copper 
mixtures at frequent intervals during the ripening 
period means the presence of copper salt upon the mar- 
keted fruit, unless it is washed off after picking. 



76 



FUNGI AND FfNUK IDi:> 



Literature. Dr. Smith's an ides concern in ir the 
injuries of peaches caused by this fungus mav IK- found 
in the Journal of Mycology, v. V, pp. 123-134, and >ul>- 
sequent issues. An account of Professor Chester's < \- 
periments is given in Bulletin XIX of the Delaware 
College Experiment Station. 



IP.A_:R,T iz 

FUNGI AFFECTING SMALL FRUITS 



FUNGI AFFECTING THE GRAPE 



The Black Rot 

Lcestadia bidwellii 

This is the most generally destructive fungous dis- 
ease of the grape in the United States. It is most inju- 
rious in southern latitudes, being much less virulent as 
far north as Northern Ohio or Western New York than 
in Tennessee or the Carolinas. Like most fungous dis- 
eases, it develops with greatest rapidity during damp, 
hot weather, or when nights with heavy dews alternate 
with hot days. 

The black rot fungus usually first appears on the 
leaves early in summer in the shape of small, sharply 
defined reddish-brown spots, having yellowish centers, 
and dark brown or blackish borders, with numerous 
minute black pustules scattered over the surface. A 
short time afterward generally about a fortnight the 
attack upon the fruit becomes noticeable. 

According to Professor F. D. Chester, who has 
studied this disease in Delaware, "the first appearance 
of rot upon the berry shows itself as a light brown spot, 
caused by the decay of the underlying pulp, this spot 
increasing in size so as to involve the entire berry. 
Simultaneous with this change, the parts first affected 
turn black and become covered with minute black pus- 
tules. Finally the entire berry dries and shrivels, the 
skin crumpling into angular folds. The entire berry is, 
at this stage, profusely and uniformly covered with the 
pustules. If a thin section be made through a rotting 
berry, the microscope will reveal the presence of minute 

79 



80 



FUNGI AND FUNGICIDES 




threads growing into and between the cells. These 
threads which form the vegetating portion of the fun- 
gus, technically mycelium, are in diameter only about 
one-sixth that of a single fiber of cotton wool. It is the 
growth of these threads through the tissues of the berry 
which causes the decay and shriveling, externally mani- 
fest as black rot. 

Microscopic Characters. At points beneath 
the cuticle the mycelium collects into little knots, which 
afterwards develop into the black pustules seen upon 

the surface. These pus- 
tules are globular thick- 
walled sacs or concept a- 
cles, technically pycni<lin, 
which at maturity are filled 
with elliptical spores, 

FIG. 38. BIT OF SKIN SHOWING PUS- kllOWI1 aS ^lOSpOTeS. The 

TITLES, WITH ESCAPING COILED stylospores commonly es- 

MASSES OF SPOKES. MAGNIFIED. ^ thrQUgh fln aper t Ure 

or pore in the summit of the pycnidium in the form of 
threads ; these threads are masses of spores glued to- 
gether by some adherent substance. Fig. 38 represents 
a small bit of the cuticle or skin of the grape, with the 
pustules considerably magnified; through the pore in 
the summit of four of them the coiled masses of spores 
are escaping." 

These stylospores are scattered through the vine- 
yard, and those which lodge upon green grapes with a 
drop of moisture present, germinate by sending out a 
little tube, whjch penetrates the skin and starts the dis- 
ease anew. 

Besides these stylospores, there are three other 
kinds of spores produced by the black rot fungus. They 
are called by botanists the spermatia, the conidia, and 
the ascospores. The latter are produced in May and 
June, by the mycelium in the berries destroyed the pre- 



THE BLACK EOT 



81 



vious year, and so are supposed to start the disease for 
the season. Full accounts of the development of these 
various spores will be found in the articles referred to 
below, under the head of Literature. 

Treatment. Spray with the ammoniacal solution 
of copper carbonate or the Bordeaux mixture five to 
eight times, making the first application when the buds 
begin to swell, early in May in the Northern States, and 
repeating at intervals of fifteen days. In case Bordeaux 




FIG. 39. OUTFIT FOR SPRAYING GRAPES. 

mixture is used, substitute the ammoniacal solution for 
the last one or two sprayings, to avoid spotting the fruit. 
The time of the first application will, of course, vary 
with the latitude, earlier in the South than at the 
North. A convenient spraying outfit for vineyard use 
is illustrated in Fig. 39. It consists of a barrel with 
pump attached, mounted crosswise in a wagon. One 
man drives and pumps, and another sprays the vines 
behind the wagon. The hose terminates in an S-shaped 
6 



82 



FUNGI AND FUNGICIDES 



pipe, by means of which the operator can spray any part 
of the vines. The great increase in value of sprayed 
over unsprayed graprs has bcm repeatedly demonstrated. 
It has been found that spraying with Bordeaux mixture 
not only prevents the disease, but keeps the vines in a 
much healthier and more thrifty condition than un- 
sprayed vines not diseased. 

Literature. The black rot fungus has been very 
frequently discussed in recent horticultural literature, 
especially by Messrs. Scribner, Galloway, Chester and 
others. The principal articles are to be found as fol- 
lows: United States Department of Agriculture, Re- 
ports, 1886, pp. 109-112; 1887, pp. 326-327; 1888, pp. 
326-334; 1889, pp, 399-405 ; 1890, pp. 394-396, and in 
various bulletins; Delaware Experiment Station, Bul- 
letins Nos. VI and X ; Proceedings Society Promotion 
of Agricultural Science, 1888, pp. 68-73; 1889, pp. 
62-64 ; 1890, pp. 58-63. 

The Downy Mildew 

Peronospora viticola 

In the Northern States the downy mildew, or 
brown rot, is one of the most destructive fungus ene- 
mies of the grape. It is distributed over nearly the 
entire eastern half of the United States, and occurs both 
upon the wild and cultivated varieties of grapes. It 
probably lived upon the former before the introduction 
of the latter. It appears usually about the time the 
vines blossom, producing upon the leaves a distinct 
whitish mildew which has earned for it its common 
name. The leaves, and often the young shoots, are 
more or less injured, and from them the fungus spreads 
to the newly formed berries, coating them also with mil- 
dew and causing them to fall off. The damage contin- 
ues throughout the summer. When larger grape berries 



THE DOWtfY MILDEW 83 

are attacked their growth is checked, and they gradually 
turn grayish or brown. 

A good example of the parasitic fungi affecting 
higher plants is furnished by this downy mildew of the 
grape. It is a minute, parasitic plant that develops 
at the expense of the tissues of the grape, thus causing 
blighting of the leaf and decay of the fruit. It attacks 
all the green parts of the vine, including the young 
shoots, as well as the leaves and berries, and, like other 
fungi, reproduces by means of spores. 

When one of these spores falls upon a leaf where 
there is sufficient condensed moisture, its contents divide 
into a number of distinct 
particles, which escape 
through an opening in the 
spore- wall. Each of these 
particles moves about in 
the drop of water on the 
leaf for a few minutes, 
then comes to a standstill FIG . 40 . SECTION OF LEAF SHOWING 
and germinates by sending MYCELIUM OF FUNGUS. MAGNIFIED. 
out a little tube somewhat as a kernel of corn in moist 
soil sends out its germinating radicle and this tube 
penetrates the epidermis, or skin of the leaf. Once 
inside, the tube continues to grow, pushing about be- 
tween the cells of the leaf, and forming the mycelium, 
or vegetative portion of the fungus, which may be 
likened to the roots of the higher plants. As there is 
little nourishment to be obtained between the cells, this 
mycelium develops minute processes, which push through 
the cell walls and absorb the cell contents. A small sec- 
tion of an affected leaf, greatly magnified, is represented 
in Fig. 40, the unshaded double-walled spaces represent- 
ing the leaf cells, the shaded part between the walls the 
mycelium of the fungus, and the projections marked 
a, a, the processes, or suckers, that penetrate the cells. 




84 



FUNGI AND FUNGICIDES 



After this mycelium has developed in the leaf for 
some time, it is ready to produce its spores. Conse- 
quently it sends out through the breathing pores, or 
stomata of the leaf, its fruiting branches. These bear 

upon their tips small oval 
bodies, which are the spores. 
Some of these fruiting 
branches are shown in Fig. 41. 
The "mildew" visible to the 
naked eye is composed of these 
fruiting branches and their 
spores. It only develops under 
certain atmospheric condi- 
tions ; so that the mycelium 
may exist in the affected parts 
of the vine for some time be- 
fore this outward manifesta- 
tion of its presence occurs. 
Besides the spores above de- 
scribed, which are produced 
during the summer season, 
and, consequently, are called 
*? spores, there is devel- 
oped in autumn a different 
class of spores, by which the fungus passes through the 
winter. Hence, these latter are called the winter spores. 
Treatment. Eau Celeste is a practical and effi- 
cient preventive of this disease. Spray first a week or 
ten days before the vines blossom ; second, as soon as 
the berries are well set ; and third, about three weeks 
later. In very wet seasons it may be desirable to spray 
a fourth time, but this is seldom done. The other cop- 
per fungicides, especially the Bordeaux mixture, would 
doubtless prove equally effective, but eau celeste has 
been most generally used against this fungus, at least in 
some of the more important grape-growing regions of 
the country. 




FIG. 4i. FRm BRANCHES, 
GREATLY MAGNIFIED. 



THE POWDERY MILDEW 85 

Literature. An excellent account of this downy 
mildew, by Professor F. L. Scribner, may be found in 
the United States Department of Agriculture, Report 
for 1886 (pp. 96-105). Since then much has been pub- 
lished, in the Department reports and bulletins, in ex- 
periment station bulletins, and in the horticultural 
press, concerning remedial measures. 

The Powdery Mildew 

Uncinula ampelopsidis 

The powdery mildew of the grape seldom becomes 
seriously destructive, except in the Southern States and 
along the Pacific coast. It only thrives in very dry 
weather, and attacks all the green parts of the vine. . 

This fungus is closely related to the powdery mil- 
dews affecting apple and gooseberry, which are discussed 
on other pages of this book. During summer reproduc- 
tion takes place by means of summer spores, which ger- 
minate upon the moist surface of leaf or fruit, the ger- 
minating tubes sending out suckers (Fig. 42 c) which 
penetrate the tissues of the host, and enable the myce- 
lium to develop on the outside of the cuticle or skin. 
In this way the mycelium may grow all over the outer 
surface of the leaf, giving it a cobwebby appearance, 
and drawing nourishment from it by means of the suck- 
ers already mentioned. After it has grown for awhile 
in this way it sends up certain vertical branches (b), 
which soon develop transverse partitions, and thus pro- 
duce the small oval summer spores. These are light 
and easily distributed by the wind, and serve for the 
rapid extension and propagation of the fungus during 
summer. 

Later in the season the mycelium produces another 
kind of spores the so-called winter spores. These are 
more complicated in structure than their summer repre- 
sentatives ; as seen under the microscope, they consist 



86 



FUNGI AND FUNGICIDES 



externally of a small spherical case, from which project 
fifteen or twenty, or sometimes more, rather lm^ drli- 
cutc appendages with recurved tips, as seen in c. Fiir. 4'1. 
This is the outer spore-case (which botanists call the 
peritltccium). If it be crushed it will break open on 
one side, and there will be pushed out about half a 
dozen small, oval, flattened bodies the inner spore 
cases, or asci within which may be seen from four to 




FIG. 42. POWDERY MILDEW. MAGNIFIED, 
a, Peritliecium; b, mycelium; <, germinating spore. 

six small bodies, which are the winter spores. By 
means of these the fungus passes through the winter. 

Microscopic Characters. A good idea of the 
structure of this powdery mildew may be obtained from 
Fig. 42. A small piece of the mycelium running over 
the surface of the leaf is represented in b; on the lower 
side are two of the peculiar suckers which penetrate the 
tissues of the host-plant to draw out nourishment for 
the fungus, and on the upper side are represented the 
vertical branches from which the summer spores are pro- 
duced, as well as one loose spore. In c one of these 



1HE GKAPE AISTHRACNOSE 87 

spores is shown in process of germination, one of the 
germ tubes having already formed a sucker on its side. 
The winter spore case, with the inner cases escaping 
through its ruptured -side, is well shown in a. 

Treatment. This disease may easily be prevented. 
According to Mr. Galloway, "it succumbs readily to 
sulphur, either in the form of flowers of sulphur, or 
solutions of the sulphide. In applying the sulphur, bel- 
lows should be used, and the first applications should 
be made ten or twelve days before the flowers open, the 
second when in full bloom, and a third three weeks or a 
month later if the disease seems to be on the increase. 
The best results are obtained with the thermometer 
ranging from 80 to 100 F. In this temperature fumes 
are given off which quickly destroy the fungus. We 
have obtained excellent results in treating this disease 
with a solution made by dissolving half an ounce of 
potassium sulphide to the gallon of water. This prepa- 
ration is cheap, and can be quickly and effectually ap- 
plied with any of the well-known spraying pumps. The 
greatest care should be exercised in making the second 
spraying, which, by the way, should be at the same 
time as that mentioned for the flowers of sulphur, in 
order to protect the blossoms from the fungus." 

Literature. An e-xcellent account of this fungus, 
from the pen of Professor Scribner, may be found in the 
Report of the United States Department of Agriculture 
for 1886 (pp. 105-109). There are many shorter arti- 
cles concerning it scattered through our horticultural 
literature. 

The Grape Anthracnose 

Sphaceloma ampelinum 

The peculiar and characteristic injury produced 
by the fungus of anthracnose easily distinguishes it 
from the other diseases of the vine. It attacks all the 



88 



FUNGI AND FUNGICIDES 



green parts of the plant, usually doing most damage to 
the young shoots and the fruit. On the former it ap- 
pears at first in the shape of 
small sound brown SJM.N. 
depressed in the center, and 
having a slightly elevated 
dark colored border. As the 
shoots grow the spots grad- 
ually elongate, and their 
middle portions become 
more distinctly depressed be- 
cause of the killing of the 
tissue. The effect upon the 
fruit is well illustrated in 
Fig. 43 ; there first appears 
a small grayish spot, having 
its margins dark brown. 
The spot gradually enlarges, 
and there is frequently de- 
veloped just inside the dark 
brown margin a bright ver- 
milion ring. On account of 
this, the disease is often 
called the "Bird's-eye" Rot. 
As the fungus progresses the 
growth of the berry is 
checked, and it finally be- 
comes a dry, withered mass 
of skin, surrounding the par- 
tially developed seeds. The 
manner of development upon 
the leaves is similar to that 
FIG. 43. ELVIRA GRAPE AFFECTED upon the green shoots. Like 

BY ANTHRACA'OSK. ^g,. f ^ ftg an fcl irac . 

nose fungus reproduces by means of minute spores, some 
of which are represented, highly magnified, at Fig. 44 c. 




THE GKAPE ASTTHRAON'OSE 



89 



When one of these spores falls upon a green leaf, stem or 
fruit where there is a particle of water, it sends out a 
germinating tube, which penetrates the skin or cuticle. 
On the inside it begins the production of mycelium 
which grows near the surface, and finally produces, in 
certain spots, quantities of spores. These masses of 
spores gradually push the skin outward, as shown in a, 
and finally rupture it and escape, as seen in #. They 
are then blown and washed about, and such of them as 
alight on the green parts of other vines when conditions 
are favorable for germination, start the fungus again. 







& 



FIG. 44. AXTHKACNOSE. 
, l>, Vertical -section of grape showing development of spores; <, spores. Magnified. 

The light colored and white varieties of grapes are 
the ones most affected by anthracnose. A bunch of 
Elviras injured by this disease is represented in Fig. 43. 

Treatment. This is a difficult disease to prevent. 
The treatment usually recommended is to cut out all 
injured canes during winter, and early in spring, before 
the buds start, to spray the vines thoroughly with a 
strong copperas (iron sulphate) solution. Mr. E. P. 
Powell has reported successful results from a solution of 
ten pounds of copperas to a barrel of water. In case 
the disease appears, a powder composed of equal parts 



90 



FUNGI AND FUNGICIDES 



of sulphur and lime may be dusted on ; or the Bordeaux 
mixture may be applied. 

Literature. Professor F. L. Scribrier IIM> pub- 
lished, in the Report of the United States Department 
of Agriculture for 188G (pp. 113-115), an extended 
account of grape anthracnose. Since then it lias been 
frequently treated of in The Journal of Mycoloyy, and 
in experiment station bulletins and reports. 




FUNGI AFFECTING THE CURRANT AND 
GOOSEBERRY 



The Leaf=spot Disease 

Septoria ribis and Cercospora angulata 

The foliage of currants and gooseberries is often 
attacked early in summer by two or more species of 
fungi, which produce small brownish spots, at first often 
no larger than a pin head, but gradually increasing in 

size until a consid- 
erable proportion of 
the leaf surface is 
affected. Some- 
times several spots 
may run together, 
forming a large 
blotch ; and these 
blotches, as well as 
the older spots, are 
often of a dead gray 
color. When the 
leaves are badly 
attacked they fall 
prematurely, so that 
the bushes may be- 
come as bare in 

FIG. 45. SPOT DISEASE OF CURRANTS. AugUSt 3S they Or- 

dinarily are in December. Of course, the effect upon 
the plants of such a loss of foliage is disastrous. If a 
heavy crop is already hanging the plant may be unable 

91 




92 FUNGI AND FUNGICIDES 

t<> ripen ii ; and, in any case, it has no opportunity to 
store u [ vitality for the coming season's fruitage. 

The life-histories of the two species of fungi con- 
cerned in the attack do not seem to have yet been defi- 
nitely worked out. Sometimes the Cercospora is the 
cause of the disease, and sometimes the Septoria. The 
spores apparently pass the winter in connection with the 
fallen leaves. 

Treatment. Spraying with some fungicide, like 
the ammoniacal copper carbonate solution, promises to 
be a preventive of this disease. The first application 
should be made early soon after the leaves fully expand. 
Gathering and burning, or composting the fallen leaves, 
will prove helpful in destroying the spores. In case the 
leaves are composted, the resulting fertilizer should, of 
course, be applied to some crop away from any currant 
or gooseberry bushes. 

Literature. This spot disease has been discussed 
by Professor A. B. Seymour, in the report of the Min- 
nesota State Horticultural Society for 1886 (v. XIV, p. 
219) ; by Professor L. II. Pammel, in Bulletin No. 13 
of the Iowa Experiment Station (pp. 67-70) ; and by 
Dr. B. D. Halsted, in the report of the New Jersey 
State Horticultural Society for 1889 (p. 156). 

The Currant Anthracnose 

Glceosporium ribis 

This disease has only attracted attention in this 
country during recent years, and has been especially 
studied in New York by Professor Dudley (Cornell Ex- 
periment Station, Bulletin XV). It first appears in 
June or the early part of July, in the shape of small, 
dark brown or blackish spots, about one-twenty-fifth of 
an inch in diameter, chiefly on the upper leaf surface. 
The spots enlarge, and the cuticle of the leaf is pushed 



\ 



THE GOOSEBERRY MILDEW 93 

upward by the developing spores, which escape through 
a small opening, in a peculiar, tendril-like mass, the 
individual spores being held together by a mucilaginous 
substance. The raising of the cuticle gives the spots a 
white or grayish tint. The infested leaves become dull 
brown or yellow in color, and drop off, commencing 
sometimes by midsummer, and defoliating the bushes in 
August. Of course, the fruit on bushes so defoliated 
does not mature properly. Spraying with fungicides, 
such as the ammoniacal solution of copper carbonate, is 
recommended to prevent this disease. 

The Gooseberry Mildew 

Sphcerotheca mors-uvce 

For many years it has been impracticable to grow 
the finer foreign varieties of gooseberries in the United 
States, on account of their liability to injury by the 
gooseberry mildew. This fungus usually appears in 
spring upon the partially developed leaves and buds, 
first showing as a sparse, cobwebby covering, which, 
later, is made to appear white and powdery by the pro- 
duction of the summer spores. The young berries are 
also attacked, generally being dwarfed and one-sided as 
they develop. As the summer progresses the infested 
leaves become brown and dead, and are generally cov- 
ered with a thick growth of the fungus mycelium. 

With most of parasitic fungi treated of in these 
pages the mycelium, or vegetative portion of the fungus 
is internal; that is, it develops inside the outer cuticle 
of the host-plant, among the cells of leaf, stem or fruit, 
sending out its fruiting branches when it has completed 
its growth. But with the class of so-called " powdery 
mildews," to which the present species belongs, the my- 
celium is external, developing on the outside of the 
host-plant. The mycelium consists of slender white 



94 



FUNGI AND FUNGICIDES 



threads which run over the surface of the leaf, and 
obtain nourishment by sending down into the cells short 
branches, often called suckers. During the summer 
these threads also send upward in the air certain other 
branches, which gradually divide into a number of 
1 tar is, as shown in a, Fig. 4G, and thus produce the 
summer spores, or conidia. These summer spores are 
very light, and are blown about by the wind; when one 
falls upon a damp gooseberry leaf it germinates by send- 
ing out a slender tube, from which the mildew starts 
anew. As the summer spores are unable to survive the 
winter, the fungus produces, especially late in the sea- 




FIG. 46. SPORES OF GOOSEBERRY MILDEW. MAGNIFIED. 

son, another kind of spores, the so-called winter spores. 
These are much more complicated in structure than the 
others. As seen under the microscope, they consist 
externally of a small round case, from which project 
about a dozen short delicate appendages, like those rep- 
resented in , Fig. 46. This is the outer spore case 
(called by botanists the perUhedum), If it be crushed 
it will break open on one side, and there will be pushed 
out a flattened oval body the inner spore case, or ascus 
within which may be seen eight small bodies, which 
are the spores (b). By means of these the fungus sur- 
vives the winter. 



THE GOOSEBERRY MILDEW 95 

Treatment. Spray with a solution of potassium 
sulphide (liver of sulphur) at the rate of one-half ounce 
to one gallon of water. Begin as soon as the leaves 
commence unfolding, and repeat the application at inter- 
vals of eighteen to twenty days. The sulphide dissolves 
more readily in hot than in cold water. This treatment 
has proven entirely efficacious for a number of years at 
the New York Experiment Station. Early in the sea- 
son the Bordeaux mixture may be used instead of the 
sulphide if more convenient. 

Literature. An excellent article concerning this 
disease, by Dr. B. D. Halsted, may be found in the 
Report of the United States Department of Agriculture 
for 1887 (pp. 373-380). It has also been discussed in 
the reports and bulletins of the New York Experiment 
Station, and in various books and papers on horticul- 
tural topics. 





PLATE X. RASPBERRY AFFECTED BY ANTHRACNOSE. 



FUNGI AFFECTING THE RASPBERRY 
AND BLACKBERRY 



The Raspberry Anthracnose 

Glceosporium venetum 

Although this fungus is a widespread enemy of 
raspberries and blackberries, public attention was first 
called to it only about twelve years ago, when Professor 
T. J. Burrill published an account of it, under the name 
Raspberry Cane Rust, in the Agricultural Review. 
Fruit growers frequently call the disease "sun scald," 
but its more proper name is anthracnose. 

This fungus especially infests blackcap raspberries 
and the thornless varieties of blackberries. It appears 
both upon the canes and leaves. On the former it may 
generally be found late in spring or early in summer on 
the young shoots, when about a foot high, in the shape 
of small reddish-purple "spots, scattered irregularly over 
the surface near the ground. As the canes grow these 
spots increase rapidly in size, their centers becoming 
grayish- white, and other spots appearing on the upper 
portions. There is an elevated dark purple margin 
around each spot, representing the division between 
healthy and diseased tissues. As the season advances 
the spots continually enlarge, many of them finally run- 
ning together to form irregular longitudinal blotches, 
which sometimes run clear around the cane and thus 
girdle it. The injury extends through the outer bark, 
frequently rupturing it, and sapwood (cambium layer), 
but usually does not penetrate the pith. As the tissue 
7 97 



98 



FUNGI AND FUNGICIDES 



is killed the purple color of the margin changes to 
brown. The purple spots also appear on the stems of 
the lower leaves, gradually extending outward, until the 
whole leaf stem may he affected. Minute purplish dots 
are also to be found upon the leaves themselves, indicating 
that the fungus is developing there. In the center of 
many of the spots one may often see little raised patches 
consisting of the spores. 

Of the effect of raspberry anthracnose, Miss Freda 
Detmers says: "The disease is not fatal the first sea- 
son, nor does it seem visibly to effect the growth of the 
young canes ; but the next season, when last year's 
young canes bear fruit, its destructiveness becomes but 
too apparent (Plate I, Frontispiece). The effects of the 
fungus are most noticeable at the time of the ripening 
of the berries, which do not attain to a normal size, but 
shrivel, and finally dry up ; the leaves are much smaller 
than healthy ones, and have a generally unhealthy ap- 
pearance, later turning yellow, then brown. The canes 
finally become blackened and die." 

The mycelium, or vegetative portion, of the rasp- 
berry anthracnose consists of slender, microscopic threads 
which penetrate between the cells of the plant, and 
absorb their nourishment; the.cells thus robbed become 
first discolored, and then they shrivel and dry up, the 
tissues finally becoming dead. Toward the center of 
this dying tissue the mycelium threads unite to form a 
mass of slender club-shaped bodies (basidia), which 
push outward on the thin bark cuticle, or skin, until 
the latter is ruptured. On the end of each of these 
club-shaped bodies there is produced a single spore 
(conidiiim). Both the club-shaped bodies and the spores 
are at first enveloped in a yellowish, gelatinous covering, 
which, however, is soluble in water, so that during the 
first rainfall it dissolves and the spores escape. The 
shape of the spores is represented in Plate XI; they 




PLATE XI. JLNTHRACJNOSK OF RASPBERRY. 



100 



FUNGI AND FUNGICIDES 



are carried to new places on the plant during rains, and 
there they germinate and start the disease anew. M;m\ 
of them are probably blown from plant to plant and 
field to field by the wind, and thus the disease is spread. 
All of these spores are the so-called summer spores 
(conidia) ; no true winter spores have yet been found. 
It is supposed that the mycelium is perennial, carrying 
the fungus through the winter. 

Treatment. Easpberry foliage is very sensitive to 
the corrosive action of fungicides, so that care in treat- 
ment is necessary. The most successful results in pre- 
venting this disease, as yet obtained, are those reported 
by Mr. W. J. Green, of the Ohio Experiment Station, 
who used a dilute Bordeaux mixture. His directions 
are as follows : "The first application should be made 
early in the spring before the leaves open, at which time 
the spraying should be very thoroughly done. The sec- 
ond application should be made soon after the young 
canes appear above ground, and the spray directed to 
them alone. The third application is to be made about 
two weeks from the date of the second, taking the same 
precaution to spray the young canes only. The fourth 
and last application should be made just previous to the 
time of blooming, in the same manner as advised for the 
second and third sprayings. Raspberry leaves are very 
tender and the mixture injures them slightly, but not 
enough to preclude its use, especially if some care is 
taken to keep it off the leaves of the bearing canes. The 
leaves on the young shoots of the current season's growth 
are not so easily harmed, hence no pains need be taken 
to keep it off them." 

Mr. Green also reports good results from the ammo- 
niacal copper carbonate solution, "with even less harm 
to the foliage, but, all things considered, the dilute 
Bordeaux mixture is preferred." It is advisable to cut 
out and burn all fruiting canes each summer as soon as 
the crop is gathered. 



ORANGE RUST OF BLACKBERRIES 101 

The most extended account of tins disease is pub- 
lished in the 1887 Report of the Department of Agri- 
culture (pp. 357-361). 

The Orange Rust 

Cceoma nitens 

The orange rust, or red rust, of blackberries, is fa- 
miliar to most growers of small fruits. The disease 
becomes noticeable as soon as the foliage expands in 




FIO. 47. ORANGE RUST. 

a, Under surface of blackberry leaf showing snots of jecidium stage; 6, same of 
raspberry leaf showing both secidium and Pnccinia spots. 

spring, affected leaves having a peculiar golden color, 
which at once distinguishes them. A little later the 
surface becomes more or less covered with small round 
patches of orange-colored spores, to which the common 
name is due. The life-history of the fungus has only 
recently been definitely worked out. 

The fungus exists on the blackberry plant in two 
very different stages. The orange spores that are devel- 
oped in spring and early summer, as shown in Fig. 48, 
belong to the cecidium stage. They germinate on the 



102 FUNGI AND FUNGICIDES 

leaves of raspberry and blackberry; the germinating 
tubes enter the stomata, or breathing pores, of the leaf, 
develop a mycelium inside, and finally produce on the 
surface the spores of the teleuto stage, which has here- 
tofore been considered an entirely different fungus, 
called by botanists Puccinia peckiana. These Puccinia 
spores are believed to be washed on to the underground 




FIG. 48. SECTION OF BLACKBERRY LEAF, SHOWING DEVELOPMENT OF 
ORANGE RUST SPORES. MAGNIFIED. 

shoots, and to infect them with the mycelium, which 
subsequently produces the orange spores of spring. 

Blackberries are most commonly affected by this 
fungus especially certain varieties but blackcap rasp- 
berries often suffer also. 

Treatment. All diseased canes should be cut out 
and burned as soon as they show signs of disease, leaving 
none to develop spores to infect other plants. In con- 
sidering varieties, select other things being equal those 
least liable to the disease. Insist on your neighbors 
keeping the rust in check, and also look out for wild 
plants that have it. A spraying with fungicides will 



ORANGE RUST OF BLACKBERRIES 



103 



doubtless assist in preventing infection, especially of the 
Puccini a stage. 

An extended account of this disease, by Mr. G. P. 
Clinton, occurs in Bulletin 29 of the Illinois Experi- 
ment Station. 




FUNGI AFFECTING THE STRAWBERRY 
The Strawberry Leaf=blight 

Sphcerella fragarice 

The strawberry leaf-blight, leaf-rust, or leaf-spot 
is the most destructive of the numerous fungous ene- 
mies of this delicious fruit. The disease apparently 
occurs in the United States wherever strawberries are 
grown, having been recorded from Maine in the north 
and east, to Florida in the south, and California in the 
west. Over a large portion of this vast territory it fre- 
quently becomes very seriously injurious. 

This fungus first appears on the upper surface of 
the leaf in the shape of small purplish or reddish spots, 
which, though minute at the start, increase rapidly in 
size. Their centers also gradually become lighter in 
color, changing from purple, or reddish, to brown, then 
to gray or white, but the margin generally remains pur- 
ple. The size of the spots varies greatly, single ones 
sometimes being a quarter of an inch in diameter, and 
others running together to form large discolored blotches. 
Badly affected leaves finally wither, turn brown and die. 
The vitality of affected plants is seriously impaired, and 
if they are not killed outright, the crop of fruit pro- 
duced by them is diminished. 

Professor' H. Garman says that if one of the dis- 
eased spots "be cut through with a pair of fine scissors, 
the leaf will be found, at the point where the spot is 
formed, much thinner than elsewhere, because of the 
killing and drying out of its substance. Examined 
under a microscope the fungus may now be found to 

104 



THE STRAWBERRY LEAF-BLIGHT 105 

have pushed through the tissues of the leaf, and to have 
formed all over the brown central region of the spot, 
but most abundantly at its margins, small whitish tufts, 
looking like microscopic shrubs. These are the fruiting 
parts of the parasite, and are made up of numerous 




FIG. 49. STRAWBERRY LEAF AFFECTED WITH BLIGHT. 

threads, each bearing at its summit a long jointed spore. 
As these latter ripen they are set free, <ind are scattered 
upon fresh leaves by winds and rains, to germinate 
there, push into the leaves and form new spots." The 
fungus is propagated by these long spores throughout 



10G 



FUNGI AND FUNGICIDES 



tin 1 summer, but in autumn the threads of mycelium 
"form solid tissue-like masses in the dead parts of the 
spots," which finally appear at the surface as small black 
dots. By means of these dots or nodules, (which are 
called by botanists schlerotia) the fungus mainly passes 
the winter, but Professor W. R. Dudley has shown that 




FIG. 50. LEAF-BLIGHT FUNGUS. MAGNIFIED. 

it is also carried through the winter by the mycelium in 
the leaves, and the so-called winter spores, or ascospores. 
Microscopic Characters. The process of devel- 
opment of the summer spores, or conidia, is represented 
in #, Fig. 50, which shows a tuft of them after having 
broken through the upper epidermis of the leaf. At c 
may be seen some of the individual conidia, three of 



THE STRAWBEBKY LEAF-BLIGHT ' 107 

which have sent out germinating tubes. The winter 
spores within their cases, as they are borne on the leaf 
in partially closed sacs called perithecia are seen in e, 
and at /some of these cases containing spores are repre- 
sented more highly magnified. 

Treatment. It has been repeatedly shown that 
this leaf-blight may be prevented by the Bordeaux mix- 
ture. Usually spraying after the crop is gathered, espe- 
cially when the plantation is mowed and burned over, 
keeps the disease sufficiently in check, but additional 
spring sprayings one when the new leaves start, and 
another just before the blossoms open will prove of 
much benefit. Young, non-bearing plantations should 
be sprayed two or three times during summer. 

Literature. The strawberry leaf-blight has fre- 
quently been discussed in the American literature of 
plant diseases. In 1885 Professor Wm. Trelease pub- 
lished an article concerning it in the report of the Wis- 
consin Experiment Station for that year (pp. 47-58). 
Professor F. L. Scribner has an elaborate account of it, 
illustrated by a colored plate, in the report of the United 
States Department of Agriculture for 1887 (pp. 334-341). 
Other articles concerning it have been published by Pro- 
fessor Arthur in the report of the New York Experi- 
ment Station (1888, p. 351) ; by Professor Dudley, in 
the Bulletin of the Cornell University Experiment Sta- 
tion (XIV) ; and by Professor Garman in the Bulletin 
of the Kentucky Experiment Station. 



III 



FUNGI AFFECTING SHADE TREES, 
ORNAMENTAL PLANTS AND FLOWERS 




PLATE XII. HOLLYHOCK LEAF AFFECTED WITH RUST. 



FUNGI AFFECTING SHADE TREES 



The Catalpa Leaf=spot Disease 

Phyllosticta catalpce 

Early in summer small discolored spots frequently 
appear in the leaves of Catalpa trees. Although minute 
at first they gradually enlarge, and two or more often 
run together to form brown or blackish blotches, which 
sometimes involve most of the leaf. In badly affected 
trees the tissues of the leaves may be so diseased as to 
cause defoliation during the latter part of summer. In 
less severe cases the affected areas may drop out of the 
leaves, round holes appearing in their stead. 

This disease is caused by a fungus which originates 
in spores like those represented in Fig. 51, b. When 
one of these spores falls upon a moist catalpa leaf it ger- 
minates by sending out tubes, as illustrated in c, of the 
same figure, and these germ tubes enter the leaf-tissues, 
where they develop a mass of mycelium, which grows at 
the expense of the leaf cells, the latter becoming disor- 
ganized and turning brown. After the mycelium has 
developed in this way for some time it produces spores 
in certain parts of the, spot, rupturing the skin, or cuti- 
cle, of the leaf, to enable the spores to escape, as shown 
in a. These spores are blown or washed upon other 
leaves where, under favorable conditions, they may ger- 
minate and start new spots. There is another fungus, 
quite different in microscopic characters from the one 
illustrated, usually found on the spots, but it is believed 
to be a secondary form growing on the disorganized 

111 



112 



FUNGI AND FUNGICIDES 



tissues, which the fungus under consideration first 
produees. 

Treatment. The burning of fallen catalpa leaves 
in autumn is ;m advisable preventive measure. Proba- 
bly early sprayings with Bordeaux mixture, or some sim- 
ilar fungicide, would prove an effectual remedy. 

The only important article on this subject that has 
come to the writer's notice may be found in the report 




FIG. 51. CATALl'A I.EAK-SI'OT. 
a, Section showing spore pi'oduction ; 6, spores; c, spores germinating. Magnified. 

of the United States Department of Agriculture for 
188? (pp. 364-366). 

The Cotton wood Leaf = rust 

Melampsora populina 

The leaves of poplars and cottonwoods are quite 
commonly covered on the underside with an orange col- 
ored powder, which consists of the spores of a rust fun- 
gus. Such leaves usually fall prematurely, so that the 
trees may be defoliated long before the proper time. 
Later in the season the orange powder is replaced on the 
leaf by reddish brown, waxy pustules. This is the win- 
ter stage of the fungus. Eaking and burning fallen 
leaves is advised, as a remedial measure. This fungus 
is discussed in the 1888 Report of the Department of 
Agriculture (pp. 390-392). Recent experiments have 



THE MAPLE LEAF-SPOT DISEASE 113 

shown that this malady maybe prevented by early spray- 
ing with Bordeaux mixture. 

The Sycamore Blight 

Glceosporium nervisequum 

The tips of branches of sycamore trees often exhibit 
a peculiar injury in spring, which is commonly attrib- 
uted to frost. The leaves turn brown, presenting a 
scorched appearance. The effect is really due to a para- 
sitic fungus, which produces its fruit in minute black 
pustules that may be found on the injured leaves. No 
remedy, except that of cutting and burning affected 
twigs impracticable in most cases has been suggested. 
The disease is discussed in the report of the Department 
of Agriculture for 1888 (pp. 387-389). 

The Maple Leaf=spot Disease 

Phyllosticta acericola 

The leaves of various species of maple are often 
attacked by this fungus, which appears late in spring or 
early in summer in the shape of minute, blackish circu- 
lar spots. As the mycelium inside the leaves develops 
the spots increase in size, and their color often becomes 
more brownish, the shade differing considerably with 
the various kinds of maple. Many of them finally 
become a half inch or more in diameter, and two or 
more often run together to form a large blotch ; in case 
of severe attacks so much of the leaf-surface may be 
affected that the foliage withers and falls from the tree. 

The disease could probably be checked by fungi- 
cides, but the application of these to large numbers of 
shade trees is usually impracticable. In nurseries, how- 
ever, they may be employed. Gathering and burning 
the fallen leaves helps to check it by destroying the 
spores. An illustrated discussion of this fungus may be 
found in the Department of Agriculture Eeport for 1888, 
pp. 383-386. 8 



FUNGI AFFECTING THE ROSE 



The Rose Mildew 

Spherotheca pannosa 

The mildew of roses is probably familiar to every 
one who has grown these plants in a greenhouse. The 
characteristic covering of mildew upon the leaves is very 
likely to appear if the roses are neglected in any way. 
Professor S. T. Maynard says that "long experience in 
growing the rose has led many to believe that the rose 
mildew is brought on by various conditions that weaken 
the vigor of the leaf, such as want of an abundance of 
plant food in a proper condition, unhealthy condition of 
the soil, often resulting from improper drainage, irregu- 
lar or over-watering, or too sudden changes of tempera- 
ture, especially after the plants have been forced at a 
high temperature. The successful rose grower, there- 
fore, is one who, by constant care and good judgment, 
always provides against any or all of the above causes." 

Treatment. The ordinary method of preventing 
the mildew is to close the house and fill it with sulphur 
fumes three times a week. The sulphur may be put in 
a thin iron kettle over a small kerosene stove, placed 
where there is no danger of upsetting, and only fire 
enough should be turned on to boil the sulphur. If it 
catches fire the plants in the house might be ruined. 
Probably spraying with copper carbonate solution, or 
a similar fungicide, would also prove an effectual 
preventive. 

114 



THE KOSE RUST 115 

The Rose Rust 

Phragmidium mucronatum 

This is a distinct and easily recognized affection of 
roses which has long been known, both in Europe and 
America, to lovers of the queen of flowers. It seldom 
attacks tea roses, usually confining its attention to the 
hardy hybrid perpetuals. It generally appears early in 
summer in the form of orange-yellow spots upon the 
leaves, their petioles, or the green growing stalks. At 
first these spots are small, but they grow in size, espe- 
cially on the leaf petioles and young shoots, where they 
generally become elongate, while the petioles and shoots 
often become twisted and otherwise deformed. About 
midsummer the orange-yellow color gives way to a brick- 
red color, the latter appearing on the same spots and 
being due to the production of a different kind of spore. 
Towards autumn still another kind of spore is produced, 
developing in small blackish masses, mostty on the 
under sides of the leaves. These masses consist of the 
so-called winter spores, which live over winter among 
the fallen leaves, and in spring start the disease again. 

Microscopic Characters. This is one of those 
fungi which produce different spores at different seasons. 
The spring form, producing the orange-yellow spots on 
the leaves, is composed of the so-called cecidio-spores. 
They are small spherical or angular bodies, which serve 
for the rapid spread of the disease as they are blown 
about by the wind. The spores forming the brick-red 
spots of midsummer are called the uredo-spores. They 
are borne on short pedicels, and though spherical in gen- 
eral outline, have the outer surface roughened by numer- 
ous projecting points. One of the spores composing the 
black spots found late in the season called by botanists 
the teleuto-spore is represented at Fig. 52. It is very 
different from either of the preceding forms, being cyl- 



116 



FUNGI AND FUNGICIDES 



indrical, divided into numerous cells by transverse parti- 
tions, and borne on a stout pedicel. According to Pro- 
fessor Scribner, these spores germinate the following 
spring by "sending out somewhat thickened tubes 
(usually one tube issues from each cell), 
which, after attaining a length several 
times that of the spore, produce several 
minute globose bodies on short and slen- 
der stalks. These bodies, named spo- 
ridia, are easily wafted from place to 
place by the slightest currents of air, and 
when they fall upon rose leaves where 
there is moisture they send out slender 
filaments, which probably bore their way 
through the cuticle into the interior of 
the leaf," where the mycelium is again 
developed, and the disease is started for 
another season. 

Treatment. Rose bushes should 
be watched early in the season, and as 
soon as any lemon-yellow spots are noticed 
the affected portions should be removed 
and burned. Raking up and burning at 
the end of the season, the leaves beneath 
any bushes that may have been affected 
during summer, is advisable, on account 
of the winter spores so destroyed. It is 
well, also, to spray such bushes, and the 
ground beneath, during winter, with a 
solution of copper sulphate, or with some 
other fungicide. Probably spraying with 
the ammoniacal copper carbonate in spring, after the 
leaves expand, would prove helpful if needed. 

A good account of this fungus, illustrated with a 
colored plate, may be found in the United States De- 
partment of Agriculture, Report for 1887 (pp. 369-371). 



FIG. 52. 

WINTER SPOKE. 
MAGNIFIED. 



THE ROSE PHKAGMIDIUM 



ir 



The Rose Phragmidium 

Phragmidium speciosum 

The peculiar appearance of this disease when attack- 
ing the stems of ro^e-i is well illustrated in Fig. 52 a. 

The bark of such 
stems is more or less 
covered with irregu- 
lar black patches, con- 
sisting of vast num- 
bers of the winter 
spores of the fungus, 
borne upon long slen- 
der stalks, as seen, 
much magnified, at b. 
The spores themselves 
are divided by trans- 
verse partitions into 
from five to seven 
cells. The mycelium 
of this fungus devel- 
ops in the inner bark 
and the*cambium 
layer of the stems, 
but is believed not to 
penetrate into the 
woody tissue. Of 
course it interferes 
with the flow of sap, 
and when, as often 
a b . happens, it extends 

FIG. 52. ROSE PHRAGMIDIUM. clear around the stem, 

a, Affected stem; 6, winter spores. it may prOVC fatal to 

the plant. The mycelium is perennial in the stems, 
living from one season till the next, so that when once 
infested there is no way of ridding a plant of it. The 




118 



FUNGI AND FUNGICIDES 



only remedial treatment suggested is to cut and burn 
infested parts of bushes. Probably spraying or washing 
the stems with the Bordeaux mixture will prove advan- 
tageous in preventing the ingress of the parasite. 

A short article concerning this fungus appears in 
the report of the United States Department of Agricul- 
ture for 1887, Page 372. 



FUNGI AFFECTING FLOWERS 



The Hollyhock Rust 

Puccinia malvacearum 

This fungus is a native of Chili, from whence, 
about 1869, it was introduced into Europe, where it has 
done much damage. It first appeared on hollyhocks in 
this country in 1886, having been accidentally imported 
into Massachusetts the previous year on another plant. 
Since then it has gradually spread in various directions. 
It appears in May and June, in the shape of yellow or 
orange spots, on the leaves and stems of the holly- 
hock. These spots occur especially on the under sur- 
face of the leaves ; they increase rapidly in size, and the 
yellow color gives way to a brown. The spots, or sori, 
are composed of two-celled spores. When they are very 
abundant they cause the plant to become sere and brown, 
preventing, in whole or in part, the production of flow- 
ers. A leaf showing the sori on the under surface is 
represented in Plate XIII. 

Treatment. When this disease appears in a new 
locality for the first time the best method will be to pull 
up and burn the affected plants at once. European 
gardeners have reported successful results from spong- 
ing all diseased parts of the plants with a mixture made 
by adding two tablespoonfuls of saturated solution of 
permanganate of potash to one quart of water. It seems 
probable that thorough spraying with some fungicide 
like the Bordeaux mixture or the ammoniacal copper 
carbonate solution, would prove helpful. In any case, 

119 



120 



11NGI AND FUNGICIDES 



the fallen leaves and dead plants should be removed and 
burned. 

Two other hollyhock diseases commonly occur. 
The more abundant is the leaf-spot, due to the fungus 
Cercospora althaina. Leaves attacked by it show at 
first small distinct spots, which rapidly enlarge, often 
running together and destroying the entire leaf-tissue. 
It affects young, as well as old, plants, and frequently 
is very destructive. 

The leaf -blight of hollyhocks is due to Phyllosticta 
althceina. Affected leaves are usually not attacked in 
so many places as by the leaf-spot, but the injury in the 
infested area is more severe, the tissues being destroyed 
as the fungus spreads. Excellent illustrations of these 
diseases may be found in the American Florist (Jan. 25, 
1894). The use of seed from non-affected plants, and 
spraying with Bordeaux mixture, are recommended as 
preventive measures. 

The Carnation Rust 

Uromyces caryophillinus 

During recent years the growing of carnations 
appropriately called the "divine flower" has become 
one of the most important branches of the floral indus- 
try. In consequence, the fungous diseases of the plant 
have received unusual attention, and effective methods 
of preventing most of them have been discovered. 

The carnation rust is the most important of these 
diseases. It first appears on the stem or leaf as a pale 
elevated pustule, over which the epidermis soon breaks, 
hanging on the edges in a ragged condition, and reveals 
a brown powdery mass which consists of the reproductive 
spores of the fungus. Like the other rusts, this fungus 
develops two kinds of spores, the uredospores, which 
may be likened to the conidia, or summer spores, of 



THE CARtfATIOtf LEAF-SPOT 121 

other fungi ; and the teleuto-spores, which are the rest- 
ing or winter spores. There is little difference, to the 
naked eye, except that the teleuto-spores are slightly 
darker in color. The uredospores are the ones by which 
the disease is rapidly propagated and spread. They may 
be blown or washed from plant to plant, spreading infec- 
tion rapidly. Carnations of all ages are liable to injury, 
which is often so serious as to ruin large plantings. 

Treatment. The experience of a number of flor- 
ists has shown that this rust can be prevented by the 
use of the dilute Bordeaux mixture, supplemented by 
careful hygienic methods. The application should be 
made upon the first appearance of the disease, or even 
before, if there is much danger of its presence, and* 
repeated at occasional intervals. Instead of the liquid 
mixture, which it may not be desirable to use on plants 
in blossom, a dry preparation is used by some growers. 
It is made as follows : "Six pounds sulphate of copper 
dissolved in three or four gallons of boiling water, stir- 
ring till thoroughly dissolved ; with this liquid and just 
enough added water, dry slake one bushel of lime (dif- 
ferent limes require a slightly varying quantity of liquid 
to slake them.) Thoroughly dampen a tight wooden 
box, and put in a layer of the lime and sprinkle with 
the copper solution till it falls into a fine dust. Put in 
another layer and sprinkle, and continue till the bushel 
of lime is reduced to a dry powder." This powder is to 
be dusted over the foliage. Sulphide of potassium one 
ounce to ten gallons of water has also been successfully 
used. 

The Carnation Leaf=spot 

Septoria dianthi 

This is a widely distributed and troublesome dis- 
ease. It appears on the leaves and stems in the shape 
of a more or less circular purplish spot with a whitish 



12:3 FUNGI AND FUNGICIDES 

center, the latter often being dotted with black by the 
fruiting portions of the fungus. The fungus penetrates 
the stem rather deeply, often cutting off the supply of 
nutriment to the flowers, and, consequently, preventing 
their development. A plant injured in this way is rep- 
resented in Fig. 53, from a photograph by Professor 
Atkinson. The spores are produced in great abundance, 




FIG. 53. CARNATION INJURED BY LEAF SPOT. 

and distributed by means of wind and water. Care in 
watering, and the use of fungicides, are the best reme- 
dial measures. 

There are certain other carnation diseases, such as 
the anthracnose, the leaf-mold, and the rosette, which 
need hardly be discussed in this connection. Partial 
accounts of them may be found in American Gardening 
for April, 1893. where also the diseases treated of above 



THE MIGNONETTE DISEASE 123 

are described. One of the fullest accounts of the carna- 
tion rust, by Professor Arthur, occurs in The American 
Florist, Feb. 18, 1892. 

The Mignonette Disease 

Cercospora resedce 

Mignonettes frequently suffer from a disease which 
may first be noticed, "either as minute pale spots with 
brownish or yellowish borders little sunken areas in 




FIG. 54. MIGNONETTE DISEASE, 
a, Spore; 6, spore stalks; e, germinating spore. Magnified. 

the succulent tissues of the leaf or as reddish discolora- 
tions which spread over the leaf, and finally develop 
into these pale spots or patches." These spotted areas 
are portions of the leaf which the fungus has invaded 
and destroyed. As the mycelium develops within the 
leaf they increase in size, and finally involve so much of 
the surface that the leaf wilts and withers ; the whole 
plant sometimes looks as if it had suffered severely from 



124 



FUNGI AND FUNGICIDES 



drouth. Black specks develop on the surface of the 
injured areas, giving it a granular appearance. These 
specks consist of the fruiting spores of the fungus. The 
young seed-pods are sometimes affected. 

If one of the little black specks be looked at from 
the side under a high power of the microscope it will be 
seen to resemble Fig. 54, which represents a tuft of 
fruiting threads after they have burst through the skin 
of the leaf. At a is seen a spore borne on the summit 
of one of these fruiting threads (b, b), while at e is seen 
a spore in process of germination. 

Treatment. Mr. D. G. Fail-child made some ex- 
periments in spraying the young plants with the Bor- 
deaux mixture, from which he concluded that if the 
young plants are carefully sprayed with the Bordeaux 
mixture the trouble may be avoided. The spraying 
should be repeated whenever the spots begin to show. 

Literature. The only American articles of im- 
portance known to me are one by Professor A. B. Sey- 
mour in The American Florist for September, 1887 
(p. 38), and another by Mr. D. G. Fairchild, from 
which the above quotation is made, in the report of the 
United States Department of Agriculture for 1889 
(pp. 429-432). 

The Verbena Mildew 

Oidium erysiphioides 

This often proves a destructive enemy to verbenas 
under glass, appearing on the leaves and young stems as 
patches of white mildew. According to Professor L. H. 
Bailey, it may be prevented by spraying with sulphide 
of potassium (one-fourth ounce to a gallon of water) 
about twice a week. Probably the ammoniacal copper 
carbonate solution, or other copper fungicides, would 
prove equally effective. 



THE PETUNIA BLIGHT 125 

The Petunia Blight 

Ascochyta petunice 

Petunia leaves are sometimes affected by a blight, 
which is likely to begin near the center and to spread in 
all directions. Sometimes rings are produced on the 
injured tissues. Like other fungi, this species repro- 
duces by means of spores, which are developed in great 
numbers. The early application of fungicides is sug- 
gested as a preventive. 

There are many other fungous diseases of flowers 
and foliage plants, but the limits of the present work 
prevent their discussion here. Illustrated accounts of 
many of them have been published by Dr. Halstead and 
others in The American Florist, Garden and Forest, 
The American Agriculturist, and other journals. 



rv 



FUNGI AFFECTING VEGETABLES 





m 




FUNGI AFFECTING THE BEAN 



The Pod=spot or Anthracnose 

Collet otrichum lagenarium 

Young bean pods, especially of the yellow or wax 
varieties, are often affected by small reddish-brown 
spots, slightly sunken beneath the surrounding area. 
As the pods develop these spots increase in size, and 
their centers become blackened. In course of time 
many of them may run together to form long discolored 
blotches upon the sides of the pods, and generally the 
blackened centers eventually become of a dirty gray or 
light brown color. The effect upon the pod of such an 
attack is disastrous ; it is shrunken and out of shape, 
and the beans within are dwarfed and shriveled. 

This disease is seldom destructive, except during 
seasons of rainy weather. It occurs in several European 
countries, and has been found over a large portion of 
the United States. It winters over, in part, by means 
of diseased seeds, which, when planted, start the fungus 
again, and it spreads rapidly when sound and affected 
string beans are sent to market in the same receptacle. 
This same fungus attacks melons, and other cucurbita- 
ceous plants, causing a rind- rot. Consequently, beans 
and melons should not folloAV each other in rotation, as 
the spores in the ground will cause trouble. 

While the attack of this fungus on the pod is most 
noticeable, it does not confine itself to this part of the 
plant. In case diseased beans are used for planting, 
the attack may be noticeable as soon as the seed-leaves 
come up, and may develop so rapidly as to injure the 
9 129 



130 



AND FU-NCUC1DES 




FIG. 55. BEAK PLANT ATTACKED BY ANTHRACNOSE. 



THE POD-SPOT OR ANTHKACNOSE 131 

stalk (Fig. 56) and kill the plant. In this way a fourth 
of the seeds planted are sometimes killed off. As the 
leaves develop they are attacked, the veins becoming 
blackened, and discolored spots appearing. Dots of a 
light pink color appear on the middle of the spot shortly 
after it has formed. A microscopic examination will 
show that these dots consist of spore masses held together 
by a mucilaginous substance, which is readily soluble in 
water. When the enveloping mucilage is dissolved the 
spores are set free, to be blown or washed about, or car- 
ried to other plants by insects or other agencies. 

Treatment. Planting in a light soil, on high, 
well-drained land, is one of the best preventives of this 
disease. Experiments in New York have shown that it 
is Avell worth while to examine the seed beans carefully 
before planting and reject all that show signs of the dis- 
ease. Then the young plants may be sprayed with 
dilute Bordeaux mixture, to which soap enough has been 
added to make a slight suds, applying first when the 
plants are two weeks old, and repeating two or three 
times at intervals of a week or ten days. Or soak the 
seed in dilute ammoniacal copper carbonate solution. 
In the case of string beans, where the pods are to be eaten, 
the spraying must cease earlier than with those crops 
where the beans themselves are to be harvested. The 
immediate removal and destruction of all plants or por- 
tions of plants which become affected is very desirable, as 
every plant so left becomes a center of infection. They 
should be taken away and burned or buried. 

Literature. The best article concerning this dis- 
ease accessible to the American student was published 
by Professor Scribner, in the report of the Department 
of Agriculture for 1887 (pp. 361-364). It is illustrated 
by an excellent colored plate. Professor Trelease pub- 
lished an earlier account in the Cultivator and Country 
Gentleman (October, 1885). Other articles of especial 



132 FUNGI AND FUNGICIDES 

value, because of their accounts of remedial treatment, 
will be found in the report of the New Jersey Experi- 
ment Station for 1891, and in Bulletin No. 48 of the 
Ne\v York Experiment Station. The latter account 
contains a list of sixteen articles, in which the disease is 
discussed. 

The Bean Rust 

Uromyces phaseoli 

This is a decidedly different disease from the an- 
thracnose of the bean. It commonly appears on both 
surfaces of the leaves in the form of small, round, brown, 
scattered spots, which at first are about the size of pin 
heads. These soon give off a brown powder, which is 
composed of the spores, or reproductive bodies of the 
fungus. In the course of the season the brownness of 
the spots changes to black. Often both brown and 
black spots may be found on the same plant at the same 
time. The blackness simply represents a later stage of 
development of the fungus. This disease is seldom 
destructive, and little has been done in the way of reme- 
dial treatment. Presumably spraying the plants with 
Bordeaux mixture will prove a preventive. 

The Bean Blight 

In some parts of America still another disease has 
proved destructive to beans. It appears to be due to 
bacteria. Mr. S. A. Beach says that "in its early stages 
this blight forms small pimples, which have a watery 
appearance. These may occur on the pods, blossoms (?) 
foliage or stems. They may or may not have a dull 
red border, but do not have either the black color or 
the sunken spots which characterize anthracnose. Mi- 
croscopic examination in the early stages of the blight 
failed to reveal the presence of any mycelium, but bac- 



THE LIMA BEAN MILDEW 



133 



teria were always present. In later stages sapropliytic 
fungi gained entrance through the diseased places m.d 
hastened the destruction which the bacteria had inau- 
gurated." The beans within the 'pods are also affected, 
many of them being more or less discolored and disfig- 
ured by the blight. Lima beans are also attacked by 
what is supposed to be the same disease. So little is 
known of this disease that the only remedial measures 
at present to be suggested are the burning of diseased 
vines, the selection of healthy seed, and crop rotation, 

The Lima Bean Mildew 

Phytophora phaseoli 

This fungus first attracted attention two or three 
years ago, in the vicinity of New Haven, Connecticut, 
where it was carefully studied 
by Dr. Eoland Thaxter, who 
has published an excellent 
account of it. It does not, 
as yet, seem to have spread 
over a wide area, but it is 
likely to do so within a few 
years. 

This mildew generally 
first appears on the sides of 
the immature pods as a whit- 
ish, woolly spot, which, dur- 
ing damp weather, increases 
rapidly in size. The threads 
of the fungus penetrate the ff)Spore ' 
pod, and may develop on its t f t- Magnified, 

outer surface until it forms a thick white coating, which 
often completely envelops the pod. The tissues of pods 
so affected are, of course, ruined ; they shrivel, blacken 
and decay. A similar injury to the young shoots is 
often produced, and sometimes the leaves also are 
affected. 




FIG. 56. LIMA BEAN MILDEW. 



134 



FUNGI AND Fr\<iK IDi:- 



This mildew is closely ivlalcil to the !)< WHY Mildew 
causing potato mi, to which it is similar in liiV-liistory 
and habits. The mycelium develops in the i issues of 
the bean plant, and* usually sends out its fruiting 
branches through the breathing pores (or stomata). 
The small oval summer spores ure produced upon the 
tips of these branches, as seen in Fig. 56, I. These 
spores generally germinate by means of the so-called zoo- 
spores, (a), in ii way precisely similar to the germination 
of the potato fungus spores described on Page 8. No 
winter stage of the fungus is yet known. 

Treatment. All leaves, stems and other refuse 
from the bean plants should be burned as soon after har- 
vest as possible. Experiments in spraying with fungi- 
cides have apparently not yet been tried, but the success 
attending spraying for the related fungus on potatoes 
indicates that good results are likely to be obtained in 
this way. The ammoniacal copper carbonate would be 
a good fungicide for the purpose. 

Literature. The most important account of this 
disease is that published by Dr. Thaxter in the report of 
the Connecticut Experiment Station for 1889 (pp. 
167-171). 



FUNGI AFFECTING THE BEET 



The Beet Rust 

Uromyces betce 

In certain portions of the United States the rust of 
sugar beets has done serious injury. It appears to have 
originated in Europe ; and in America has been especially 
destructive in California. Beets attacked by it become 
dwarfed and discolored. 

Professor L. H. Pammel, of the Iowa Experiment 
Station, has recently published the following account of 
the life-history of this fungus : "Ik is characterized by 
having three stages the aecidio (cluster-cup) stage, the 
uredo (red-rust) stage, and the teleuto (winter) stage. 
The first, or cluster-cup stage, occurs on the leaves and 
stems of seed beets. The cluster-cups contain chains of 
orange-yellow spores. These germinate under favorable 
conditions, sending out a little tube, which enters the 
leaf through its breathing pores. On the inside it devel- 
ops the mycelium between the leaf cells, sending into 
the cells themselves small 'suckers,' which absorb their 
contents. After a time this mycelium produces, in cer- 
tain places, spores of another kind called the uredo 
spores, which are pushed out through the skin of the 
leaf. These spores soon germinate and spread infection 
to other plants. Late in the season still another kind 
of spore is found. It is known as the teleuto-spore, or 
winter-spore. These do not germinate until the follow- 
ing spring, when a tube known as the promycelium is 
pushed out. This tube is branched, and bears small 

135 



136 



1C Mil ANI> FUNGICIDES 



lateral bodies, known :i> sporidia. These germinate, 
and when Jallmi: on the proper host, produce the aecid- 
ium stage, thus completing the cycle of the year." 

Treatment. The development of the disease upon 
seed beets, where alone, according to some ant horit i<->, 
the first stage is passed, may probably be prevented by 
spraying with some of the copper fungicides the Bor- 
deaux mixture, for example. The removal and burning 
of affected leaves is also recommended. 

Literature. A good account of this disease, with 
figures of the spores, may be found in the United States 
Department of Agriculture report for 1887 (pp. 35Q-3~>'-}). 
It has also been discussed by Dr. Halsted, in the Bul- 
letin of the Iowa Agricultural College for 1888 ; and by 
Professor Pammel, in Bulletin No. 15 of the Iowa Ex- 
periment Station (pp. 235-236). 

The Beet Leaf=spot Disease 

Cercospora bet i cola 

This disease appears to be more widely prevalent in 
America than the leaf-rust. It first appears on either 
the upper or lower surfaces of the leaf, or on both, in 
the shape of small pale brown, more or less circular 
spots, with lighter colored margins. At first these 
spots may be no larger than a pin-head, but they grad- 
.nally increase in size, and often run together and form 
large discolored patches. As the spots grow older they 
become darker colored. TA'hen the 'attack is serious 
much injury may be accomplished in lessening the size 
of the crop. This disease attacks both the sugar beets 
and the ordinary varieties of cultivated beets. It has 
also been found upon various varieties of mangolds. 

The affected tissues are shrunken by the action of 
the fungus. By the aid of a lens one can see, here and 
there on the diseased surfaces, the long, slender, cylin- 



THE BEET LEAF-SPOT ]) IS EAST. 1 )>7 

drieal spores projecting outward from the breathing 
pores, or through raptures in the skin. Each of these 
snores is divided by transverse partitions into several dis- 
tinct cells, and each of these cells is capable of sending 
out a germinating tube to start the disease in a new 
place. In autumn these spores fall to the ground with 
the foliage, and remain there over winter in condition to 
infect a new crop the following spring. 

Treatment. The last statement in the preceding 
paragraph indicates the desirability of rotation of crops 
in preventing this disease. In case the same ground 
must be used for beets several successive seasons, the 
leaves should be removed when the crop is gathered, 
and burned, or composted, and the resulting compost 
applied to some other crop than beets. If these meas- 
ures are not sufficiently successful, it is probable that 
spraying with the common fungicides will prove an effi- 
cient preventive. 

Literature. The most important article concern- 
ing this disease yet published in America occurs in Bul- 
letin No. 15 of the Iowa Experiment Station. It is by 
Professor L. H. Pammel. 



FUNGI AFFECTING THE CABBAGE AND 
CAULIFLOWER 



The Club Root 

Plasmodiophora brassicce 

The club-root of cabbage, cauliflower, turnip and 
other cruciferous plants, is well known to most garden- 
ers in the eastern and central States. It is also found in 
many parts of Europe, having been known in Scotland 
for more than a century. The disease is sometimes 
called "clump foot," "club foot," and "fingers and 
toes;" it often does great damage, sometimes destroy- 
ing entire crops. The trouble has been attributed to 
various causes, but it is now definitely established that 
the agency chiefly concerned is a low form of fungus 
one of the slime-molds the vegetative portion of which 
does not even develop mycelium threads, but grows as a 
semi-liquid slimy mass. This gains access to the tissues 
of the young roots and develops in the cells, causing the 
tissues to become malformed in various ways. After 
developing in this way awhile the mold produces innu- 
merable spores, which are set free by the rotting of the 
root tissue, and left in the soil. Here they germinate 
by the production of zoospores, which remain in the 
soil apparently indefinitely, and penetrate when oppor- 
tunity offers the thin-walled cells of roots and rootlets, 
thus continuing the cycle of existence. 

The disease commonly attacks seedlings in the seed 
bed. Such plants begin an abnormal root-development, 

138 



THE CLUB ROOT 



139 



a few roots becoming greatly swollen, as shown in Fig. 
57, and the leaves, instead of having the dark green 
color of healthy foliage, become pale green or yellowish. 




FIG. 57. CIAir, HOOT OF < AliBAUK. 



Such an injury, of course, prevents the proper develop- 
ment of the plant, which becomes worthless. 

The injury to other crops than cabbage is often 
severe. Cauliflower is frequently attacked with fatal, 
effect, as may be seen in the photo-reproduction in Fig. 



140 ITN-GI AND PUXGK : DE 

58, whilo turnips commonly suiTcr in n most disastrous 
manner (Fig. 59). But cultivated crops are not the only 
hosts of llu- fungus a i'act which makes it still more 




FIG. 58. CLUB ROOT OF CAULIFLOWER. 

difficult to contend against. Various weeds belonging 
to the cruciferous family are also attacked by the club 
root fungus. Shepherds' purse, for example, is com- 



THE CLUB JRCOT 141 

monly infested, the roots presenting the appearance 
shown in Fig. 60. Because of this, crop-rotation, which 




FIG. 59. CLUB UOOT OF TURNIP. 



so often proves serviceable in checking fungous diseases, 
may possibly become ineffectual ; but this is, neverthe- 



142 FUNGI AND FUNGICIDES 

less, one of the best preventive methods. Crops on 
land which has previously been planted to cabbages or 
turnips are most liable to suffer, but the disease is said 




FIG. 60. CLUB ROOT OF SHEPHERD'S PURSE. 

sometimes to appear on new land. Crops on limestone 
soils are usually quite free from attack. 

Clean farming, involving the removal and destruc- 
tion, by burning, of all refuse of the cabbage or turnip 



THE CLUB BOOT 143 

field, together with constant crop-rotation, are the chief 
safeguards against the club root fungus. The only way 
to lessen attack is to use preventive measures ; for when 
once the fungus has obtained a hold upon the plant, it 
cannot be gotten rid of. It is probable that methods of 
preventing it from attacking seedlings in the hotbed can 
readily be found, but few definite experiments on the 
subject seem yet to have been made in America. Eng- 
lish writers assert that if the soil of the seed bed be 
treated with carbon-bisulphide before the seeds are 
planted, the traces of the fungus in the soil will be de- 
stroyed, and the seedlings escape attack. If many of 
the seedlings in the seed bed show the disease, the whole 
lot better be pulled up and burned, and other plants 
obtained. The use of lime at the rate of seventy- 
five bushels to the acre, has been recommended as 
a preventive, and, apparently, backed by practical 
experience. 

Excellent accounts, in which the life-history of this 
fungus is fully discussed, occur in the Journal of My- 
cology (v. VII, pp. 79-88), by A. C. Eycleshymer ; in 
Ward's Diseases of Plants ; and in Bulletin 98 of the 
New Jersey Station, in which Dr. Halstead first pub- 
lished the illustrations appearing above. An effect very 
similar to club root is often produced on the roots of a 
great variety of plants by the little worms called 
Nematodes. 



FUNGI AFFECTING CELERY 



The Celery Blight 

Cercospora apii 

The common blight of celery, sometimes incorrectly 
called the rust, is a destructive and widespread disease, 
which appears from the middle to the last of summer. 

Its presence is usually 
first seen in the shape 
of small, irregular, yel- 
lowish-greeii spots, less 
than a quarter of an 
inch in diameter, upon 
the leaves. These spots 
increase rapidly in size, 
and soon change to a 
brown color. In a short 
time they so spread as 
to form great blotches, 
involving a large por- 
tion of the leaf, which 
may finally wither and 
die. The fungus caus- 
ing this disease repro- 
duces by means of elon- 
gate spores. When one 
of these falls upon a 

FIG, 6i. CELERY LEAF SHOWING moist celery leaf it ger- 

BLIGHT. minates by sending out 

a long tube, which penetrates the leaf, and develops the 

mycelium among the cells. Here it continues growing 

144 




THE CELERY BLIGHT 



145 



for some time ; then certain branches of the mycelium 
are pushed through the breathing pores, or stomata, of 
the leaf, and produce on their tips the spores. Fig. 62 
#, represents a sectional view of a leaf having the myce- 
lium developed among the cells, and the spore-producing 
branches- coming out through a breathing pore. In a, 
of the same figure, two spores in process of germina- 




a I 



FIG. 62. CELERY LEAF-SPOT. 
a, Spores germinating; 6, section of leaf showing fungus. Magnified. 

tion are represented. No winter spores have yet been 
discovered. 

It has been found, in some localities, that celery 
growing in the shade is seldom affected by this fungus. 
Hence it is recommended that, unless fungicides are to 
be employed, as advised below, the celery bed be placed 
in situations shaded by trees ; or that it be artificially 
10 



146 FUNGI AND R-\<iI< I 

shaded by screens of lath, or similar material. It is 
important, also, that refuse leaves affected by the dis- 
ease be gathered and burned. 

Literature. Articles concerning this fungus occur 
in the United States Department of Agriculture reports 
for 1886 (pp. 117-120) and 1888 (pp. 308-309); Pul- 




FIG. 63. CELERY LEAF INJURED BY LEAF-BLIGHT. 

letin 2, New Jersey Experiment Station, and 1891 report 
(pp. 250-253) ; also Bulletin No. 51, New York Experi- 
ment Station. 

The Celery Leaf=blight 

Septoria petroselini, var. apii 

This is a disease somewhat similar to the blight 
already described, which attacks all portions of the cel- 
ery plant except the root. Its presence is commonly 
first shown by the appearance, on the leaves or stems, of 
watery areas, which soon afterwards become spotted 



THE CELERY LEAF-SPOT 147 

with small black dots, projecting slightly above the 
cuticle of the plant. These dots consist of the spores, 
or reproductive bodies of the fungus. A leaf injured by 
this malady is represented in Fig. 63. The black spots 
appear also on the stems and seeds of the fruiting plant, 
as shown in Plate XV, and it seems probable that the 
fungus is disseminated by means of sch diseased seeds. 
The malady commonly appears in the seed-bed, and it 
is, at least, a safe precaution not to plant seeds so spot- 
ted. Those who harvest celery seed should not gather 
from plants so diseased. 

Accounts of this malady occur in report of New 
Jersey Experiment Station, 1891 (pp. 255-256), and 
Bulletin 2 ; report Massachusetts Experiment Station, 
1891 (p. 231) ; and Bulletin No. 51, New York Experi- 
ment Station. Still another celery leaf fungus, belong- 
ing to the genus Phyllosticta, has been described by 
Dr. Halsted. 

Treatment for Celery Diseases. The most 
promising method of preventing these celery diseases is 
that of spraying the young plants with dilute Bordeaux 
mixture, beginning soon after they come up in the seed- 
bed, and continuing the treatment at intervals of ten 
days or two weeks, at least until transplanting time. 
Later sprayings with either the Bordeaux mixture or 
the ammoniacal copper carbonate solution, are advisable, 
if the disease appears in the field. Such sprayings may 
be made, according to some experiments, up to the time 
of blanching, without danger of injuring the plants for 
food, but it would be better, usually, to discontinue the 
treatment some weeks earlier. Refuse celery should not 
be left upon the field, especially where the same ground 
is to be planted to celery the following season. 




PLATE XV. MAGNIFIED VIEW OF CELERY SEED AJSD PORTIONS OF 
STEMS DOTTED WITH FUNGUS OF LEAF-BLIGHT. 



THE SOFT ROT OF CELERY 



149 



The Soft Rot of Celery 

The central portions of celery plants are frequently 
attacked by a disease which causes what growers call the 
"soft rot." A portion of a plant 
so affected is represented in Fig. 
64. This appears to be due to 
minute bacteria. It especially 
attacks plants banked or stored in 
wet places, and sometimes causes 
serious losses. Golden sorts ap- 
pear to be most liable to the mal- 
ady. Dr. Halsted advises, as a 
preventive, keeping celery dry or 
placing it under pure water. His 
discussion is found in the 1892 
report of the Jew Nersey Experi- 
ment Station. The injury of this 
malady is not confined to the core. 
The leaves are also affected ; they 
become spotted with brown, the 
spots often having the watery ap- 
pearance that bacterial blights 
are likely to produce. Instances 
are on record in which large crops 
have been ruined by this disease. 

FIG. 64. SOFT ROT OF * 

CELEKY. It seems quite possible that the 

bacteria causing this malady are the same as the ones 
causing tomato and potato blight and similar diseases. 




FUNGI AFFECTING THE ONION 




The Onion Mildew 

Peronospora schleideniana 

This disease appears upon the tops of onions as a 
grayish, moldlike, velvety coating, which is followed by 
more or less wilting of the affected leaves (Fig. 65). 
Seed onions seem to be the most liable 
to injury, and crops grown on low, damp 
ground, are more subject to attack than 
those in higher, drier situations. The 
fungus has been known in Europe as a 
serious enemy, for many years, but has 
only been recognized in America for 
about a decade. The threads of the fun- 

FIG. (55. ONION 

LEAF AFFECTED gus push about between the tissue cells 
WITH MILDEW. O f the host, destroying their contents 
and causing the collapse of the leaves. Certain branches 
are sent out through the breathing pores of the leaf, on 
which the spores are developed, as shown in Fig. 66. 
The cpores are pointed-oval in shape, and have a faint 
purplish tinge ; they are easily detached, and wafted or 
washed from plant to plant by wind or water. Under 
favorable conditions they quickly germinate, entering 
the tissues through the breathing pores by means of a 
short germ-tube. Thus the fungus may spread rapidly. 
Besides these conidia, or summer spores, the fungus 
develops certain winter spores, called cospores, by 
means of which it passes the winter. These are pro- 
duced within the tissues, of the host-plant, and carry 

150 



THE ONION SMUT 



151 



the fungus over from season to season. They have a 
thicker wall than the conidia, and are spherical rather 
than oval. 

Treatment. The destruction, by fire, of all refuse 
tops in which the resting spores may pass the winter, is 
one of the most important remedial measures. Such 
tops should never be turned under unless the ground is 
to be used for some other crop the following year. 
Eotation of crops will probable provo Hie most snccess- 




FIG. Go. DEVELOPMENT OF SPOltliS. MAGNIFIED. 

ful general remedy. Where the use of fungicides is 
practicable these, no doubt, can be employed to good 
advantage. 

Literature. Professor William Trelease published 
an excellent account of the onion mildew, in 1883, in 
the first report of the Wisconsin Experiment Station. 
Dr. Thaxter also has a good discussion of it in the report 
of the Connecticut Station for 1889 (pp. 155-158), and 



152 



II M,I AND 



Professor Dudley ;i notice of it in Bulletin 1.") of tin- 
Cornell Station. 

The Onion Smut 

Urocystis cepulce 

The smut of onions has been known to occur in 
America for about thirty years, although it was not defi- 
nitely named and described by botanists until 1877. It is 
widely distributed in the United States east of the Mis- 
sissippi river, and appears to be especially destructive in 
the onion-growing regions of Connecticut. Dr. Roland 
Thaxter, recently mycologist to the experiment station 
of that State, has carefully studied the disease, publish- 
ing an excellent illustrated account of it in his report 
for 1889, from which the accompanying figures, and 
much of the following information, are taken. 

According to Dr. Thaxter, "the presence of smut 
in onions is first indicated by one or several dark spots 
at different heights in the leaves of seedlings, which arc- 
seen to be more or less opaque when the plant is held up 
to the light. These dark appearances may be seen in 
the first leaf, before the second leaf has begun to develop 
at all, and are more commonly found just below the 
"knee;" though they sometimes occur above it. After 
a time, usually while the second leaf is developing, lon- 
gitudinal cracks begin to appear on one side of these 
spots, which widen and show within a dry, fibrous 
mass, covered with a black, sooty powder made up 
wholly of the ripened fruit or spores of the fungus, 
which are blown or washed out onto the ground. In 
some cases the smut may appear only toward the upper 
end of the first leaf, and become cut off from the main 
body of the plant by the withering of the former. In 
such a case an onion which has shown smut in its first 
leaf appears, in some instances, to recover, showing no 



THE ONION SMUT 



153 



signs of smut in its subsequent growth ; but, as a rule, 
the same dark appearance shows itself in the second leaf 
and those subsequently formed, and if the seedling is 
pulled up and examined, the whole 
plant will be found to be pervaded 
by the disease, to a greater or less 
extent. Plants thus diseased, espe- 
cially if the soil is dry, very com- 
monly succumb early, dying while 
in the second or third leaf. The 
stronger plants, however, especially 
if the ground is moist, are able to 
resist the smut sufficiently to make 
a considerable growth, and many 
survive even up to the time of har- 
vesting. Fig. 67 represents such an 
onion reduced to one-third its nat- 
urul size, and is a typical example 
of the appearance presented by smut- 
ted onions that have survived until 
midsummer. In such specimens the 
smut shows itself by black eleva- 
tions upon the bulb, running down 
to its very base, and extending up 
ward into the leaves, the outer of 
which, in the present instance, have 
split open, showing the characteristic 
sooty powder composed of spores 
mingled with the stringy mass of 
dead leaf tissue. As a rule such 
onions always die, either drying up By SMUT ONE . THIRD 
or rotting soon after they are NATURAL SIZE. 
pulled." When onions are grown upon the same land 
for several successive seasons the smut, after it once gets 
started, gradually increases, until, at the end of five or 
more years, the soil is so full of smut that the field gen- 




FIG. 67. ONION AFFECTED 



154 



FUNGI AND FUNGICIDES 



orally must be abandoned and some other crop substi- 
tuted. But even then the smut remains in the soil 
eral years according to some observers, as many as 
twelve in such a condition that onions cannot be 
safely planted. 

The black powdery masses that develop upon onion 
leaves affected by smut consist of the spores, or repro- 
ductive bodies of the fungus (Fig. 68 a). They are blown 
or washed into the soil, where, after resting for a period 

sometimes until the 
following spring, some- 
times longer they ger- 
minate by sending out 
a tube (b), which soon 
develops a number of 
secondary spores, or spo 
ridia (Fig. 68 x). These 
sporidia themselves have 
the power of germinat- 
ing sending out a short 

FIG. 68. O>'IOX SMUT. ? , x i i 

a, Spore; 6, spore germinating;,, sporidia tube ( C ) WlllCh entei>S 
germinating. Magnified. the young plant jlist 

starting from the seed. This infection apparently 
occurs before the plant has appeared above ground ; and 
while, as just indicated, it probably is usually due to the 
germinating sporidia, it is also probable that it is some- 
times Directly due to spores which do not develop spo- 
ridia. After the fungus has once gained access to the 
young onion plant, the development of mycelium begins, 
and continues until a new 6rop of spores is produced. 

Local Dissemination. Dr. Thaxter states that 
"the local dissemination of smut is due to four principal 
causes. First, through agricultural implements ; plows, 
harrows, weeders, rakes, etc., which spread the soil con- 
taining smut spores, both by scattering the surface earth 
over a smutted field, and, unless they are thoroughly 




THE ONION SMUT 155 

cleaned, by carrying earth containing smut spores into 
fields subsequently worked upon. Secondly, through 
the adherence of the same smutted earth to the feet of 
men and farm animals, and its consequent transportation 
from one part of a field to another, or to different fields ; 
an agency by no means unimportant. Thirdly, the 
smut spores may be readily washed, with surface earth, 
from higher to lower ground, as is a matter of common 
observation. Fourthly, popular opinion to the contrary, 
the spores being practically imponderable, may be readily 
blown, with other dust-like material, either about the 
same field, or into adjoining fields. The reason that 
this mode of dissemination is of less importance than 
some others lies, probably, in the fact that the spores 
being formed and making their exit from the onion com- 
paratively near to the ground, are readily w r ashed into 
it by rain, and have little opportunity for blowing 
directly into the air, as is the case with corn smut, for 
example." 

Treatment. The simplest method of avoiding 
injury by onion smut is to transfer the planting to new 
land whenever the disease becomes destructive. But of 
course this is only applicable either where one grows 
only a comparatively small number of onions, or has a 
large amount of land. 

It has already been stated that infection by smut 
apparently takes place before the young plant appears 
above ground. In the case of corn and other grain crops 
affected by various species of smut, the fungus enters 
the plant when very young. These facts would lead us 
to suppose that if young onions were started in soil free 
from smut, and then transplanted to smutty soil, they 
would escape the disease, because the period of infection 
has been passed. And such is said to be the case with 
transplanted seedlings. Consequently, in the practice 
of transplanting onions, which is highly recommended 



150 



I I M.I AM) FUNGICIDES 



by leading horticulturists for other reasons than this, 
there is a simple and etVh;ient remedy. Concerning the 
practical value of .transplanting, a word further maybe 
said. Kxperiments made at the Ohio Experiment Sta- 
tion, by Mr. W. J. Green, indicate that by starting 
onions in forcing houses or hotbeds the yield may be 
nearly doubled, without involving any more labor. 
Concerning the cost of cultivation, Mr. Green says : 

"The difference in cost of cultivation was consid- 
erable, the ratio being about one to two in favor of the 
bed of transplanted onions. At the first weeding both 
beds were weedy, but while the weeds were as large as 
the onions in the bed where the seed was sown, making 
weeding difficult and slow, the task was comparatively 
easy in the other bed. At the second weeding it was 
necessary to remove many of the small onions in the 
bed where the seed was sown, an operation which is 
equivalent to an extra weeding. The work of weeding 
was but one-half on the bed of transplanted onions that 
it was on the other bed. Counting the extra trouble of 
growing in the greenhouse and transplanting, the work 
on the two beds was about the same for the whole sea- 
son ; that is, transplanting adds nothing to the cost of 
growing the crop, aside from the necessity of a green- 
house, hotbed or cold-frame, in any of which the plants 
can be started. 

"The difference in the time of ripening was about 
one month, in favor of the transplanted onions, making 
it possible to use them for bunching, and also to market 
the crop at an earlier date than could be done with those 
sown in the open ground. The yield of the transplanted 
onions was about double that of the others." 

Experiments by Dr. Thaxter indicate that possibly 
flowers and sulphur and air-slaked lime mixed together 
in equal parts, and sowed with the seed, may have a pre- 
ventive effect. The same authority says that "all refuse 



THE ONION SPOT DISEASE 157 

of whatever kind that is left on the field should be 
burned as soon as practicable, and, although onion land 
is usually kept so clean that it cannot be burned over in 
the fall, this practice will be found very advantageous 
when it is possible. At the second and subsequent hand 
weedings all onions which show smut in the .second or 
third leaf should be pulled, collected in a basket or other 
convenient receptacle, and burned at once. This prac- 
tice involves very little trouble, and the folly of leaving 
the larger smutted onions to discharge crop after crop of 
spores upon the ground,- as the leaves successively 
mature, is apparent ; especially when the enormous 
number of spores thus formed is considered. It is 
hardly an over-estimate to say that a single large onion 
may mature during a season something like a cubic inch 
of smut, which means between one and two thousand 
millions of spores, each capable of producing a smutty 
onion in the following season." 

Literature. Dr. Thaxter's article so freely quoted 
in the above account, will be found in the report of the 
Connecticut Agricultural Experiment Station for 1889 
(pp. 129-153). It contains numerous references to the 
European literature of the subject. An earlier article, 
by Professor W. G. Farlow, will be found in the report 
of the Massachusetts State Board of Agriculture for 
1876-77 (p. 164). 

The Onion Spot Disease 

Vermicularia circinans 

This is a fungus which has been described as inju- 
rious to white varieties of onions after they are housed. 
It starts in the field on part of the bulbs ; these produce 
many spores, by means of which it is propagated in the 
bins when the conditions are favorable ; that is, when 
the atmosphere of the storage room is warm and moist. 



158 I I N(i| AM) IT M.I < I 

The discuss appears in Hie field ;H a Uackish growth on 
the outer bud scales. It is not; noticeable at first, and 
when closely examined will he seen to consist of a cen- 
tral dot or ring, surrounded by larger rings. During 
damp weather the black growth develops rapidly, some- 
times in the form of circles, and sometimes simply 
spreading without circles, as in Fig. 69 a. When the dis- 




b 

FIG. 

a, Spot disease of onions; t>, snores. 



ease first appears it only affects the outer scales, but 
later it penetrates deeper and causes rot. 

When highly magnified the black specks on the 
bulb scales resemble Fig. 69 Z. Each consists of a mass 
of mycelium having long, black, pointed bristles, around 
the bases of which the small, slightly curved spores are 
produced in great numbers. These spores are easily 
blown upon surrounding bulbs, where they may germi- 
nate and start the disease again. 

Treatment. One of the best safeguards against 
this disease is to put dry onions in dry bins, in cool and 
dry storerooms. The onions should not be allowed to 



THE ONION SPOT DISEASE 



159 



heat at all, and bins which have contained diseased 
onions should be disinfected by spraying or dusting with 
some fungicide before they are again used. It has been 
suggested that sprinkling the bulbs with dry, air-slaked 
lime might prevent the spread of the disease. 

Dr. Thaxter's article upon this disease may be 
found in the report of the Connecticut Experiment Sta- 
tion for 1889 (pp. 163-165). 



FUNGI AFFECTING MELONS AND 
CUCUMBERS 



The Cucumber Mildew 

Plasmopara cubensis 

In America this disease has been recognized as a 
destructive enemy of cucumbers and other cucurbitaceous 
plants for only three or four years, but it is aln-ndy 
widely distributed, and in many places has done much 
damage. The fungus attacks the leaves in a manner 
somewhat similar to the attack of the downy mildew of 
the grape. The mycelium, after entering the leaf from 
a germinating spore, develops between the cells, and 
sends suckers into the cells to absorb their contents. In 
due time this mycelium sends branches out through the 
breathing pores of the leaf, on the tips of which are 
produced the spores. The injured leaves turn yellowish 
or brown in spots, and if the attack is severe, are finally 
destroyed. 

The destruction of all refuse leaves that may have 
been infested, and spraying with fungicides, are the best 
remedial measures. A rather full account of the fungus 
may be found in the eighth report of the Massachusetts 
Experiment Station (pp. 210-212; 1890), and in Amer- 
ican Gardening, April, 1803. 

The Bacterial Blight 

This disease has been especially troublesome in the 
Southern States, where it has done much damage to the 
melon crop. It is also destructive in the truck-growing 

160 



THE BACTERIAL BLIGHT 



161 



regions of the North, and it is possible that it is due to 
the same germs as the bacterial blights and rots of vari- 
ous other vegetables, such as celery, potato, tomato, etc. 
"Soon after the plants are up, and usually by the time 
they have reached out a foot or so upon the ground, the 
trouble begins. The stem may become moist, in a man- 




FIG. 70. CUCUMBElt LEAF AFFECTED WITH MILDEW. 

ner to suggest what is termed ' water core 'in apples. 
This may be close to the base of the plant, or midway 
between that point and the tip of the vine. Sometimes 
one leaf -stalk decays first, and the disease spreads from 
it to other parts. Occasionally the free young end melts 
away with the trouble.- When tissue that is freshly dis- 
eased is examined, it is found swarming with bacteria, 
11 



162 FUNGI AND FUNGICIDES 

and no other cause for the disorganization is to be seen. 
Not unfrequently the leaves become spotted that Is, 
certain areas decay and fall away. If a leaf freshly 
affected is held toward the light, the diseased places 
may be easily detected, by the peculiar discoloration, 




FIG. 71. MUSKMELON LEAF SHOWING BACTERIAL BLIGHT. 

being due to the excess of moisture a sogginess, so to 
speak." (Halsted.) 

Effective preventive measures for this vexatious mal- 
ady have yet to be found. Presumably rotation of crops 
will prove an important method, but if the same germs 
affect many widely separated plants, a specially devised 
rotation may be required. 



1HE MELON LEAF-SPOT 163 

The Melon Leaf=spot 

A muskmelon leaf injured by a fungus belonging to 
the genus Phyllosticta, is represented in Fig. 72. It 
causes light colored spots, which may eventually break 



FIG. 72. MELON LEAF-SPOT DESEASE. 

away and give the leaf a very ragged appearance. The 
fungus reproduces by means of small spores, which are 
developed in great abundance. Presumably spraying 
with fungicides will have a preventive effect. 



FUNGI AFFECTING THE POTATO 



The Downy Mildew, or Late Blight 

Phytophora infestans 

A sufficiently full account of this disease has already 
been given in the Introduction (pp. C-lo). A large pro- 
portion of the potato maladies in the I'nited States hav<-, 
until lately, been attributed to this fungus; but recent 
observations indicate that other agencies are at work- 
particularly the fungus known as Macrosporium soluni, 
and apparently certain bacteria. The downy mildew 
disease has been culled, by Professor Jones, of Vermont, 
the "late blight," to distinguish it from the "early 
blight," caused by the Macrosporium. Tho late blight 
fungus generally appears rather late in the season ; and 
its attack is frequently sudden and fatal, affected plants 
being entirely destroyed in a few days. The tubers are 
also commonly affected, rotting and producing, during 
I he process, a foul smell. This disease is most destruc- 
tive during warm, moist weather, at such times spread- 
ing very rapidly. It commonly begins as a single spot 
on a leaf, from which it spreads throughout the plant, 
r/ad produces on the lower leaf-surface a mildew-like 
growth, to be distinguished by the naked eye. This dis- 
ease can be prevented by spraying several times with the 
Bordeaux mixture. 

The Early Blight, or Leaf=spot Disease 

Macrosporium solani 

This disease appears early in summer in the shape 
of small brown, brittle spots, scattered over the leaf. 



THE BACTERIAL BLIGHT 165 

Careful inspection shows that their upper surfaces are 
more or less roughened by darker areas rising above the 
dead gray tissue. The spots gradually enlarge, and 
finally run together to form large brown patches, the 
intermediate tissues becoming yellowish or sickly green 
in color. The entire plant finally withers, and dies long 
before the proper period, the tubers being small gen- 
erally less than half full size. But the tubers do not rot 
and are of good quality. This fungus has proven diffi- 
cult to study in the field, the spores being produced 
only on part of the affected plants. It winters over in 
the spore stage on the dead vines. 

The Bacterial Blight 

Besides the two maladies already discussed, there is 
a potato disease due to bacteria, although it is probable 
that the Macrosporium blight has frequently been attrib- 
uted to these organisms. Bacteria often develop in 
tissues invaded by the fungus just named; but there are 
good reasons for believing that a genuine bacterial 
trouble frequently develops in all parts of the plant. It 
generally starts from the seed planted, which becomes 
rotten. The vines die prematurely, often wilting rather 
suddenly, and the young tubers decay. This disease is 
more troublesome in southern latitudes than at the 
north. 

Treatment of Potato Diseases. A large num- 
ber of experiments in many sections of the United States 
have shown that these various maladies may be pre- 
vented by spraying with the Bordeaux mixture. It has 
been repeatedly shown that vines thus sprayed remained 
in a healthy normal condition long after the untreated 
vines were dead, and that, consequently, the tubers 
developed to a much larger size, with a greatly increased 
yield. The results of an experiment of this kind, at 



THE BACTERIAL BLIGHT 



167 



the Rhode Island Station, are shown in Plate XVI, 
which is reproduced from a photograph taken August 
20th. "The two rows in the center of the figure were 
not treated with the mixture, consequently the leaves 
all blighted and withered up soon after August 1st, leav- 
ing only the bare, dead stems when the photograph was 
taken ; while the leaves and vines in the rows on either 
side, which had been sprayed with the Bordeaux mix- 
ture, were fresh and green." 

The effect upon the tubers, of treatment with Bor- 
deaux mixture, as it resulted in some experiments by 
Professor Jones, of Vermont, is shown in Fig. 73. The 





b 

FIG. 73. 
a, Yield of unsprayed plot; 6, of sprayed plot. 

treated vines yielded marketable tubers at the rate of 
two hundred and ninety-one bushels per acre, while 
those untreated yielded only at the rate of ninety-nine 
and one-half bushels per acre. 

As a general rule, the first application of Bordeaux 
mixture may be made when the vines are about one-third 
grown, or earlier if signs of disease appear. Repeat the 
application when it is washed off in about a fortnight 



1G8 



1 i v.i AND FUNGICIDES 



usually. ' Add halt' ;i |<>imd of London purple or Paris 
green to cadi barrel of the mixture whenever the Col- 
orado beetles threaten injury. 

The Potato Scab 

Oospora scabies 

The "scab" of potatoes is familiar to every experi- 
enced farmer. Like the pear blight, the theories con- 
cerning its cause have been many and varied ; but the 
recent investigations of Messrs. Thaxter and Bolley have 
established, with considerable certainty, that the injury 
is really due to the attacks of a low form of fungus life, 
which develops in the tissues of the growing tubers. 
Two forms of scab, the "deep scab" and the "surface 
scab," have been recognized by some writers, but there 
is a strong probability that these are simply different 
phases of the same injury. At any rate, there is little 
difference, from a practical standpoint, and they Avill 
not be separately discussed here. 

It has often been noticed that scabby potatoes are 
more abundant in fields heavily fertilized by barnyard 
manure. This is now believed to be largely due to the 
fact that if scabby potatoes are fed to stock, the spores 
of the fungus can pass through the alimentary canal 
uninjured, and can multiply abundantly in the manure 
heap. Consequently they will be transferred to the field, 
and when the potato tubers are developing, will attack 
them and produce the injury. 

The fungus-producing scab is an obscure one, which 
botanists have studied only recently. It can generally 
be seen on partially developed scabby potatoes, in the 
shape of fine white threads running over the surface. 
It reproduces by means of spores. Repeated experi- 
ments have shown that if scabby potatoes are planted, a 
large percentage of the resulting crop will be scabby. 



THE POTATO SCAB 



Professor II. L. Bolley has shown that what id probably 
this same disease occurs also on beets planted on potato 
ground. 

Treatment. Dr. Roland Thaxter, after several 
years of careful study, summarizes the preventive meas- 
ures to be taken against this disease as follows : (1) The 




FIG. 74. POTATO INJURED BY SCAB. 

cccd must be free from any scabs. (2) Land which has 
produced scabbed crops in previous years, either of pota- 
toes or of beets, or has been fertilized with manure from 
scab-fed stock, must not be planted to potatoes. (3) 
Gc:ib potatoes should never be fed to stock, under any 



170 



FUNGI AND FUNGICIDES 



circumstances, unless they have heen thoroughly cooked, 
even if the laud on which the manure is to be used is 
not to be cropped with potatoes at once. (4) In gen- 
eral, any fertilizer is to be preferred to barnyard manure 
for potatoes, whether tlie stock has been fed with di.~ 
cascd potatoes or not. (5) If it is suspected that a cnp 
is scabbed, it is of great importance to dig the potatoes? 
as soon as possible after they are mature, since the seal 
spots increase in size, and deepen, as long as they an 
left in the ground, and what is at first a comparative!) 
slight surface injury may be sufficiently extended { ren- 
der tubers worthless, which would otherwise have been 
marketable. 

Experiments at the North Dakota Station, by Pro- 
fessor Bolley, show that the disease may be prevented by 
soaking the seed in a weak solution of corrosive subli- 
mate. Concerning its use, he says: "One wishing to 
try the corrosive sublimate treatment, if to no greater 
extent than to assure the raising of healthy, smooth 
potatoes sufficient for seed the following year, will find 
it best to proceed about as follows : Procure an ordinary 
barrel, and fit into the base a common wood en faucet. 
Purchase of a druggist two ounces of finely pulverized 
corrosive sublimate (Mercuric bichloride}. Lmpty this 
all into two gallons of hot water, and allow it to stand 
over night, or until, apparently, all dissolved. Place in 
the barrel thirteen gallons of water, then pour in the 
two gallon solution. Allow this solution to stand in 
the barrel four or five hours, during which time it is 
several times thoroughly agitated, to insure equality of 
solution before using. Select as fair seed potatoes as 
possible, wash off all the old dirt, and immerse as many 
as you can or wish to treat at one time in the solution 
one hour and thirty minutes. At the end of this time 
turn off the solution into another vessel. The same 
solution may thus be used a number of times, if wished. 



THE POTATO SCAB 1?1 

After drying, the potatoes may be cut and planted as 
usual. Plant upon ground that has not previously borne 
the disease. The potatoes may be cut before treatment 
if wished. 

"Caution: The corrosive sublimate is a strong 
poison, and too great care cannot be exercised in its use. 
The strength of the solution as here recommended, one 
part in one thousand, is the same as that used in sur- 
gery, and is not such as to work injury unless taken into 
the stomach. Great care should be taken in handling 
the pure substance, and all treated potatoes should be 
planted. Tlie solution should not be placed in metallic 
vessels. " 

This method has been tried by Mr. T. B. Terry, 
the well-known Ohio specialist, and endorsed. The 
potatoes may be conveniently dipped in the solution if 
they are first placed in coarse sacks, like coffee sacks, 
through which the liquid readily passes. Mr. W. J. 
Green, of the Ohio Experiment Station, has recently 
announced that excellent results in scab prevention were 
obtained by soaking the seed for one hour in dilute Bor- 
deaux mixture. 

Literature. Dr. Roland Thaxter's articles on the 
subject are found in the reports of the Connecticut Ex- 
periment Station for 1890 and 1891, and Professor Bol- 
ley's contributions in Agricultural /Science, Vol. IV, and 
Bulletins Nos. 4 and 9 of the North Dakota Experiment 
Station. Other articles may be found in the Gth, 7th 
and 8th reports of the Massachusetts Experiment Station, 
and in various other reports, bulletins and periodicals. 



FUNGI AFFECTING THE SWEET POTATO 



The Black Rot 

Ceratocystis fimbriata 

There are several kinds of "rot" affecting the sweet 
potato, which have been carefully studied by Dr. Byron 
D. Halsted, of the New Jersey Experiment Station. To 
his studies we are indebted for much of the following 
information upon the subject : 

According to Messrs. Halsted and Fuirchild, "the 
most conspicuous sign of the present disease, and the 
one which distinguishes it from other diseases, occurs 
upon the potatoes themselves. It consists in the pres- 
ence of dark, somewhat greenish spots, varying from a 
quarter of an inch to four inches in diameter, sometimes 
covering the greater part of the root and extending some 
distance into the tissue. These spots, w^hen once seen, 
can not be mistaken, as they are simply sunken areas 
with distinct margins, like spots burned into the potato 
with a metal die, which has left the skin uninjured. 
Should the slightest doubt as to the identity of the dis- 
ease remain, after a superficial examination, the removal 
of a small portion of the skin, exposing the olive-green 
tissue below, would dispel it. Among the sprouts, or 
young plants grown in hotbeds, the disease manifests 
itself in dark lines upon the lower portion of the shoot, 
and sometimes of the lower leaves, giving rise to the 
name of "black shank" among the growers. These 
dark lines or blotches often appear upon etiolated por- 
tions of the stem, and are almost black in color. In 
very severe cases the tip of the sprout wilts and dies. 

172 



THE BLACK ROT 173 

No appearance in the field has so far been observed, that 
would distinguish hills diseased with black rot from 
those attacked by some other of the numerous rots ; but 
the dark sunken areas on the potato, and the black dis- 
colorations of the sprouts, can scarcely be confused with 
any other sweet potato disease." 

This black rot has been found seriously injurious in 
New Jersey, Maryland, Delaware and Virginia, and it 
probably occurs in many other portions of the United 
States. It frequently destroys twenty-five per cent, of 
the crop, the injury taking place mostly after the pota- 
toes are stored, when the fungus can easily pass from 
root to root. 

A microscopic examination of portions of diseased 
roots shows the presence of threads of mycelium, which 
push about between and through the cells, absorbing 
the starchy matter with which the latter are normally 
filled. These mycelial threads have thick walls, and are 
olive-brown in color. Under suitable conditions of 
warmth and moisture, they produce on the outside of 
the skin of affected root or stem numerous spores (called 
conidia) of two distinct forms ; and there are also 
formed within the substance of the potato certain flask- 
shaped bodies, within which are produced a third kind 
of spores. The disease is likely to start from affected 
potatoes planted in hotbeds to obtain sprouts. The 
mycelium may pass directly from the root to the young 
sprout, or the latter may be inoculated by means of 
spores. Such sprouts, when planted, produce diseased 
roots. 

Treatment. The following preventive measures 
are recommended by Messrs. Halsted and Fairchild : 

1. The first and most important precaution to be 
taken, in combating the disease, is to plant only per- 
fectly healthy seed in the hotbed, even if it is necessary 
to import such. This preventive measure is most essen- 



174 



FUNGI AND FUNGICIDES 



tial, as diseased seed will give diseased sprouts, which, 
in turn, will grow a crop of worthless potatoes. 

2. The selection of healthy sprouts is plainly nec- 
essary, in case the fungus gets into the hotbeds, and 
under no circumstances should diseased plants be put 
into the field. The test of using copper fungicides in 
the hotbed has not been made, but, from analogy, seems 
to promise assistance. If the fungicide is used the 
shoots should be kept green with it until pulled. 

3. Fields which have become so impregnated by 
the disease that they refuse to grow profitable crops, had 
best be added to the regular farm rotation. This 
method will, if continued for several years, allow the 
accumulated infective material to burn itself out by con- 
suming all available food material in the soil. 

4. Decaying roots and the refuse after digging 
should be carefully removed from the field and burned, 
as such debris adds to the food of the parasite. 

5. The use of large quantities of barnyard manure 
probably favors the development of the trouble, since it 
adds greatly to the decaying vegetable matter of the soil. 
Where the use of commercial fertilizers can be made to 
take the place of manure, it will certainly be desirable 
to make the change. 

6. Although no experiments have yet been com- 
pleted upon the matter, it is probable the spread of the 
disease in the bin may be checked by dipping the roots 
in one of the copper mixtures, preferably the ammoni- 
acal solution, before storing for the winter. What effect 
tobacco smoke, or the fumes of sulphur, would have in 
checking the disease in the bins remains to be ascertained. 

Literature. The two most important articles con- 
cerning this disease that have come to the writer's notice 
are, first, one by Dr. Halsted, published in 1890, in Bul- 
letin 7G of the New Jersey Experiment Station (pp. 
7-14) ; and, second, one by Dr. Halsted and Mr. D. G. 



THE BLACK ROT 175 

Fairchild, consisting of an admirable resume of the 
studies of these gentlemen, which appeared in 1891 in 
the Journal of Mycology (v. VII, pp. 1-11). The reader 
desiring information concerning the spores and spore 
formation of the fungus should consult this article. A 
discussion of the various other diseases of the sweet 
potato will be found in Bulletin 76 of the New Jersey 
Experiment Station. 




FUNGI AFFECTING THE SPINACH 



The Spinach Mildew 

Peronospora effusa 

Spinach, when forced for market undi-r glass, is 
subject to attack by several fungous diseases, which have 
been investigated by Dr. B. D. 
Halsted. The mildew is one of 
the most destructive of these mal- 
adies. It is closely related to the 
downy mildew of the potato, and 
produces "gray, slightly violet, 
patches of a velvety texture, upon 
the under side of the leaves, while 
from the upper side they hav 
pale yellow shade, due to the 
of the green color." If a cross 
section of the leaf be made through 
one of these patches, and n minute 
piece placed under the microscope 
on a glass slide, the fungus will 
be seen to have a structure similar 
to Fig. 75, which represents on 
the lower part the cells of the leaf 
having the mycelium of. the fun- 
gus running between some of 
them, sending here and there 
"suckers" into the cells them- 
selves to absorb their contents, 
and pushing out through the 
breathing pore, a, the fruiting 
M3fiea evelopmenl >fspore ' stalk, b, which bears the spores, c. 
At d one of the spores is shown, more magnified. These 
spores are scattered to other plants, where they germinate 




THE SPINACH ANTHRACNOSE 



177 



by sending out slender tubes, which 
through the breathing pores. 



may enter the leaves 



The Spinach Anthracnose 

Colletotrichum spinacece 

This is, perhaps, the most destructive of the spin- 
ach diseases, as it grows rapidly, and, in consequence, 
soon spreads over many plants. "The first indication 
of its presence," writes Dr. Halsted, "is an indescriba- 
ble moist appearance of the usually circular affected 
part; followed by the appearance 
of minute brown pustules, while at 
the same time a gray color develops 
and the diseased area becomes dry. 
The anthracnose is shown in Fig. 
76, where an affected leaf, much 
reduced in size, is seen, with some 
portions killed by the fungus. No 
particular part of the leaf is first 
attacked, and, therefore, no two 
leaves appear alike. In some cases 
the largest leaves will be diseased, 
in other plants only the younger 
ones ; but sooner or later plants that 
are affected will become entirely 
unfit for use. To test the rapidity 
of the growth of the anthracnose, 
healthy plants, grown in the labo- 
ratory, were inoculated with the 
spores, and in from five to seven days the spots sown 
had become thoroughly diseased, and were bearing mul- 
titudes of spores." Spinach is also subject to attack by 
a leaf-blight, a white smut and a black mold disease. 

Treatment for Spinach Diseases. As already 
stated, the diseases discussed above affect most severely 




FIG. 76. SPINACH LKAF 

AFFECTED BY AX- 

THKACNOSE. 



178 FUNGI AND FUNGTCII'I> 

spinach forced under glass for early market. That 
grown out of doors is not infested to nearly so great an 
extenj. As it is impracticable to treat the spinach 
plants with the ordinary copper fungicides, except, pos- 
sibly, when very young, such cultural methods must be 
adopted as will reduce the chances of infection to a 
minimum. These methods include the collecting and 
burning of refuse leaves affected by any of the diseases, 
and the changing of the location of the beds used for 
spinach each year, if possible ; and if not, the changing 
of the soil instead. Dr. Hulsted suggests raking a mix- 
ture of equal parts of air-slaked lime and sulphur into 
the soil a measure that is well worth trying. The flor- 
ist paints his heating pipes with a sulphur mixture, to 
keep the air of the greenhouse saturated with sulphur 
fumes, in order to prevent mildew, and it seems possible 
that the air in hotbeds might also be more or less satu- 
rated with such fumes to prevent fungous diseases. 

Literature. The only important general account 
of these spinach diseases so far published in America is 
to be found in Bulletin No. 70 of the New Jersey Exper- 
iment Station. It is by Dr. B. D. Halsted, and to it 
the present writer is indebted for the figures and infor- 
mation given above. 



FUNGI AFFECTING THE TOMATO 



The Tomato Rot 

Macrosporium tomato 

The common tomato rot is often extremely destruc- 
tive, both in field culture and under glass. It usually 
first becomes noticeable when the fruit is about half 
grown, appearing at the blossom end as a small blackish 
spot, that increases in size as the tomato develops. The 
tissues beneath the spot are destroyed by the fungus, so 
that the fruit becomes flattened on top, and the inside 
of the tomato is blackened. The fungus may finally 
involve the whole fruit, producing a shrivelling and 
blackening, that is only too familiar to most experienced 
gardeners. An excellent account of this fungus, by Mr. 
B. T. Galloway, may be found in the 1888 report of the 
United States Department of Agriculture (pp. 339-346.) 

Treatment. Professor L. H. Bailey, than whom 
no American has more thoroughly studied the tomato, 
says that this rot " can be kept in check by spraying 
with Bordeaux mixture or ammoniacal carbonate of cop- 
per ; but it is difficult to apply the material to untrained 
plants, especially upon rich soil, where they make a 
thick growth. Plants which are trained to stakes and 
pruned admit of thorough treatment. The rot appears 
to be less, as a rule, if the plants are so trained that the 
fruits and vines dry off quickly after rains and dews. 
In single-stem training out of doors, rot was greatly 
reduced this year. Straw placed underneath vines ap- 
pears to increase the tendency to rot, and the same 

179 



180 



FUNGI AND FUNGICIDES 



appears to be true of heavy dressings of stable manure. 
The less improved varieties of tomatoes, like many of 
the old angular sorts, and the cherry and plum varieties, 
are almost exempt from attack." 

The Winter Blight 

Professor Bailey has described, under the name of 
Winter Blight, a malady of greenhouse tomatoes that 
sometimes proves disastrous to attempts to force this 
fruit. It has the general appearance of a bacterial 
blight, although no definite proof has yet been made 
that it is caused by bacteria. When first attacked the 
leaves become dwarfed and somewhat faded, with indis- 
tinct yellowish spots on the surface. "The spots grow 
larger, until they often become an eighth of an inch 
across, or even more, and they are finally more or less 
translucent. This injury to the foliage causes the plants 
to dwindle, and the stems become small and hard. 
Fruit production is lessened, or if the disease appears 
before the flowers are formed, no fruit whatever may 
set. In two or three instances in which young plants 
were attacked, the disease killed the plant outright ; but 
a diseased plant ordinarily lives throughout the winter, 
a constant disappointment to its owner, but always 
inspiring the vain hope that greater age or better care 
may overcome the difficulty." This blight has not been 
observed to attack the fruit. As stated above, it appears 
to be due to bacteria a species of micrococcus but is 
different from the tomato blight of the Southern States. 
Various remedies have been tried without success, and 
the best preventive measures are those of the immediate 
destruction of all blighted plants, and the use of new 
Boil in the greenhouse each fall. 

The Bacterial Tomato Blight 

Tomatoes in the Southern States are commonly 
affected by a blight similar to, if not identical with, the 



THE BACTERIAL TOMATO BLIGHT 181 

bacterial blight of potatoes. The tissues of diseased 
plants teem with bacterial germs, and no other form of 
fungus is present at first. The malady has been studied 
by Dr. B. D. Halsted, who has published a preliminary 
account of it in Bulletin No. 19 of the Mississippi Ex- 
periment Station. The presence of the disease is usu- 
ally shown by the wilting of the younger leaves, especially 
those at the ends of the stems, and the yellowing of the 
older foliage. The stems themselves also become af- 
fected, and when closely examined, are seen to have 
numerous watery spots. A longitudinal section of such 




FIG. 77. VMOHTK.D TOMATO LEAVES. 

a stalk reveals a greenish, watery center, very different 
from that of the healthy plant. 

There is a blight affecting squashes and melons that 
seems to be the same disease as this, and also as the 
potato blight already referred to. Consequently neither 
of these crops should follow the other on the same land, in 
case the disease has appeared. It is believed that the 
soil becomes so contaminated with the germs that, in 
case either of these crops follows the other, the injury 
may appear again. In addition to proper rotations, the 
burning of all diseased plants and rubbish in the field, 
and spraying early with Bordeaux mixture, are recom- 
mended as remedial measures. 



FUNGI AFFECTING SEEDLINGS AND 

CUTTINGS 
The Damping=off Fungus 

Pythium DeBaryanum 

The malady known as " damping-off " is familiar to 
all experienced gardeners. It affects the seedlings and 
cuttings of a great variety of plants in the propagating 
bed. It appears oftenest when the soil surface is damp, 
the temperature high and the sky clouded. "Its first 
appearance is indicated by a slight paleness and droop- 
ing of the seedlings. If these be carefully removed, 
it will be seen that the root, either throughout its length, 
or in portions, is beginning to shrink and decay, and 
that the root hairs are destroyed. Later, if the plant is 
not vigorous enough to resist tae fungiis and to put 
forth secondary roots, the disorganization of the tissue 
extends to the stem, resulting ultimately in the toppling 
over of the plant and its thorough decay, although, in 
some instances, the plant remains green for some days 
after falling. This extends from one plant to another, 
until only a few or none of the seedlings in a bed may 
be left."* The plants attacked and the soil between 
them becomes more or less covered with the mildew-like 
growth of the fungus mycelium. Recent investigations 
indicate that the fungus gains entrance to the plants 
through the roots. 

Treatment. According to Mr. T. W. Galloway, 
of Harvard University, the fungus may be destroyed by 



*T. W. Galloway. 

1S2 



THE DAMPING-OFF FUNGUS 183 

giving the soil the conditions (heat and moisture) favor- 
able to the germination of the spores, and then, a few 
days later, exposing it thoroughly to a very dry, hot 
atmosphere, so as to kill the delicate growth of the fun- 
gus. It seems likely that the trouble might be avoided 
by watering the plants with an extremely dilute solution 
of copper sulphate say a pound to two hundred gallons. 
The preventive measures recommended by gardeners, 
are the avoidance of a high temperature and moist at- 
mosphere, keeping plants stocky, giving plenty of air, 
and changing the soil frequently. 

Literature. A discussion concerning damping off 
may be found in the American Garden for June, 1890 
(XI, 347-350) ; also in H. Marshall Ward's Diseases of 
Plants; and in the Transactions of the Massachusetts 
Horticultural Society for 1891. The latter contains the 
article by Mr. Galloway from which the above quotations 
were made. 




FUNGI AFFECTING CEREAL AND 
FORAGE CROPS 




PLATE XVII. OATS SMUT. 



FUNGI AFFECTING OATS 



The Loose Smut 

Ustilago avence 

Some estimates of the loss due to this fungus have 
already been given in the Introduction (p. 2). A good 
representation of its appearance is seen in Plate XVII. 
The black masses consist of millions of minute spores, 
by means of which the fungus reproduces itself. The 
spore masses ripen about the time the oats are in bloom, 
when the chaff enveloping the embryo seed is spread 
wide open. The spores are blown over the field, and 
many of them lodge on the inner side of the chaff parti- 
cles, where they remain as the seed ripens, and are not 
dislodged when it goes through the threshing machine. 
The smut spores are also largely distributed from the 
smutted heads and lodged in the chaff of sound kernels 
during threshing, although it is probable that only a 
small percentage of them get far enough into the chaff 
to infect the plants that develop from the kernels. 

After the spores have lodged in the chaff they re- 
main there until the oats are planted. Then they ger- 
minate by sending out little tubes, which enter the 
young plant through the first leaf-sheath. These tubes 
are only able to gain access to the plants during a very 
short period of the growth of the latter. After the oats 
have pushed out the second leaf the danger of infection 
by smut is past. When the germinating tube has entered 
the plant it sends out branches in all directions, pene- 
trating the stem and all its parts, thus forming the 

187 



188 



FUNGI AND FUNGICIDES 



mycelium, or vegetative portion of the fungus. As the 
oats plant grows this mycelium also develops, taking 
possession of all the new tissues of the host, and form- 
ing within the head a mass of thick threads. These 
threads eventually produce vast numbers of spores, so 
using themselves up in the operation that they become 
gelatinous, and finally altogether disappear, leaving 




FIG. 78. SMUT SPOKES GERMINATING. MAGNIFIED. 

nothing but the powdery mass of spores, which are 
blown about to infect other plants, and thus begin anew 
the cycle of existence. 

The smut mycelium usually produces no peculiar 
effect upon its host-plant early in the season. Infested 
plants are seldom distinguishable from healthy ones 



THE LOOSE SMUT 189 

until it is nearly time for the oats to blossom. Then 
comes a sudden change; the spores develop rapidly, and 
are dry, powdery masses before the plants are through 
blooming. When one of the branches of a stooling 
plant is infested, the others from the same root usually 
are also, a result of the entrance of the smut so soon 
after the seed germinates. It sometimes happens that 
only a part of the spikelets of a head are attacked, and, 
according to Kellerman and Swingle, "in a few cases 
smutted heads have been collected where the smut has 
destroyed the grain and flowering glumes, while the 
large outer husks are yet entirely sound. Such a head 
would scarcely be seen to be smutted unless carefully 
examined." Most of the best authorities agree that 
there is very little danger of infecting oats with smut 
from the spores in barnyard manure applied to the soil. 
The mycelium of the oat smut fungus is composed 
of extremely delicate threads, and the spores are very 
minute, ranging from one-five thousandth to one-three 
thousandth of an inch in diameter. They are oval, or 
sub-globose in shape, with the outside wall spiny, or 
warty, having minute elevations all over its surface. 
One side is lighter colored than the other. In water or 
in a nutrient solution these spores- germinate readily, as 
seen in Fig. 78, the germinating tube appearing on the 
light side of the spore. As these tubes grow, cross par- 
titions (c, d, e, f,) frequently appear, and sometimes the 
peculiar little cells called sporidia are developed (a). 
These sporidia might be called temporary spores, because 
if placed in a nutrient solution, or manure water, they 
grow something as spores do. Some authors have 
claimed that on account of their presence in manure 
applied to the land, oats may be infected with smut, but 
this is disputed by Jensen and others. When massed 
together the spores are of a dark, dusky brown color, 
but when separated and viewed with the microscope 



190 



FUNGI AND FUNGICIDES 




FIG. 79. OATS GER- 
MINATING. 



they are clearer and lighter, though still brown. Pro- 
fessor Kellerinaii estimates that a compact cubic inch <f 
smut would contain 64,000,000,000 spores. 

Treatment. In 1887, Professor J. L. Jensen, of 
Denmark, announced that the smut of oats and wheat 
can he prevented by soaking the seed for five or ten min- 
utes in water heated to 133 F., with- 
out injury to the germinating quali- 
ties of the seed. Further experiments 
in Europe by the same investigator, 
and in America by several experi- 
menters notably Keller man and 
Swingle in Kansas, and Arthur in 
Indiana have abundantly justified 
these claims, and have demonstrated 
that by this simple treatment agricul- 
turists can prevent, practically, all of 
the loss now suffered from this dis- 
ease. And, strangely enough, these experiments have 
shown that the treatment indicated not only prevents 
the smut, but that it also hastens the germination of the 
seed and increases the yield, above that which the pre- 
vention of the smut accounts for, to such an extent that 
it would pay to treat it were no smut present. The 
hastening of germination has been well represented by 
Professor Arthur, in Fig. 79, showing oats that have 
been in a germinator three days ; a, having been previ- 
ously soaked in a solution of copper sulphate ; b, having 
had no treatment; and c, having been soaked in hot 
water. It will at once be seen that the hot water has 
hastened the germination, ana that the copper sulphate 
has retarded it. In Fig. 80 are represented the same 
kernels after they had been growing two weeks on moist 
blotting paper; d is the one treated with copper sul- 
phate ; e the one untreated ; and / the one soaked in 
hot water. As will be noticed in the engraving, the 



THE LOOSE SMUT 



191 



relative growth of the three plants is practically the 
same as it wr.s after the seeds were three days in the 
germinator. 

In Kansas Professor Kellerman made a special series 
of experiments, which showed that there was an increase 




FIG. 80. OATS PLANTS TWO WEEKS OLD. ONP>HALF NATURAL SIZE. 

of from four to eight bushels per acre over that ac- 
counted for by the mere prevention of the smut, when 
the seed was treated with hot water. 

Professor Arthur has shown that the oats may be 
treated with hot water long before the time of planting, 
with as good results, both as to prevention of smut and 
increase in yield, as when treated just before planting. 



I 1 .!'.' l-TNdl AND l-TX(!lril>l-> 

The following method ,f treatment with hot water 
has been recommended, as adapted to the facilities of 
most farmers. Have ready for the work come coffee 
sacks, two ordinary wash-tubs, a good supply of hot 
water and a clean barn floor. Partially fill tub No. 1 
with water heated to about 130 F., and tub No. 2 with 
water at 140 F. Then fill the coffee sacks with the 
oats to be treated, and, taking one sack at a time, im- 
merse it a minute or two in tub No. 1, for the purpose 
of partially heating the oats ; then lift it up, let it drain 
for a moment, and then dip it in tub No. 2, leaving it 
there for from five to eight minutes, turning and km ad- 
ing the sack to get all the seed soaked. Then empty 
the oats on an airy floor if possible, in the sunshine or 
a draft of wind, and on a dry day and let them become 
thoroughly dry. A supply of hot water should be kept 
on hand, some of which is to be poured into the tubs at 
frequent intervals to replenish the supply and keep up 
the temperature, which must be determined often by a 
good thermometer. In tub No. 2 the water should 
never get above 145, nor below 133 

For a long time solutions of copper sulphate have 
been used to prevent grain smut, but in the light of our 
better knowledge they should be discarded. They retard 
the germination of the seed and decrease the yield. 

Experiments at the Kansas Station, by Professor 
Kellerman, show that oat smut may also be prevented 
by soaking the seed for twelve hours in a solution of one 
pound of potassium sulphide (liver of sulphur) to ten 
gallons of water. " Place the seed in a wooden vessel, 
and pour on the solution until the seed is covered several 
inches deep. Stir the solution before pouring on the 
grain, and thoroughly mix the seed several times before 
taking the latter out of the solution. Then 

spread out to dry. It will probably be best to sow the 
seed as soon as possible, and before it becomes thor- 



THE OATS BUST 193 

oughly dry." The hot water treatment, however, is 
probably the better one. 

Literature. An account of Professor Jensen's 
experiments may be found in the Journal of the Royal 
Agricultural Society of England (v. 24, part II, 1888). 
The following publications also contain accounts of this 
disease : Kansas Experiment Station, Bulletins 15, 22 ; 
report for 3889, pp. 213-288; Indiana Experiment Sta- 
tion, Bulletin 35 ; North Dakota Experiment Station, 
Bulletin JSTo. 1 ; United States Department of Agricul- 
ture, Farmer's Bulletin No. 5. 

The Oats Rust 

The rust of oats is essentially the same as that of 
wheat, being caused by the same fungi, and the account 
given on Pages 200-201 will suffice for this. 




IS 



FUNGI AFFECTING WHEAT 



The Bunt or Stinking Smut 

Tilletia feet ens 

This is the most destructive smut affecting wheat. 
It differs from the loose smuts in that the individual 
kernels are affected, instead of the whole head. Accord- 
ing to Professor Arthur, wheat plants injured by this dis- 
ease "thrive about as usual, the head fills and the chaff 
is distended, as if with normally plump grain. A close 
observer will notice, however, that already before wheat 
heads out the diseased plants have a darker green color 
and somewhat more luxuriant appearance. When the 
grain is only six inches high or so, this difference in 
appearance is quite striking, the affected plants being 
darker green and taller, as if droppings of manure had 
forced them to extra growth. The growth does not con- 
tinue so long, however, as in the healthy plants, so that 
they do not usually become so tall, and are premature in 
heading and ripening up the leaves. The characteristics 
now become rather more evident. The affected heads 
retain a bluish-green, or greenish- lead color, for some 
time after the sound ones begin to ripen, and then take 
on a bleached appearance, in strong contrast to the yel- 
low of the sound heads ; the heads being much lighter 
stand more erect, and the chaff and beard are more open 
and spreading (Fig. 81)." If the injured kernels are 
broken open they are found to contain a solid mass of 
bla<5k powder the spores of the fungus. 

The life-history of this fungus does not differ essen- 
tially from that of the loose smut of oats already dis- 
cussed (pp. 187-193). 

194 



THE BUNT OR STINKING SMUT 



195 



Treatment. This smut may be prevented by the 
hot water treatment mentioned in connection with oat 
smut. Mr. W. T. Swingle gives the following directions 
for treating seed wheat : 

"Provide two large vessels as two kettles over a 
fire, or boilers on a cook stove the first containing warm 





FIG. 81. WHEAT BUNT. 



water (say 110 to 130) and second containing scalding 
water (132i). 

"The first is for the jmrpose of warming the seed, 
preparatory to dipping it into the second. Unless this 
precaution is taken, it will be difficult to keep the water 
in the second vessel at a proper temperature. 



19G II Mil AND FUNGICIDES 

"The seed which is to be treated must be placed, a 
half bushel or more at a time, in a dosed vessel, that 
will allow free entrance and exit of water on all sides. 
For this purpose a bushel basket made of liejivv wire 
could be used, with which spread wire netting, say 
twelve meshes to the inch, or an iron frame could be 
made at a trifling cost, over which the win; netting could 
be stretched. This would allow the water to pass freely, 
and yet prevent the passage of the seed. A sack maoY 
of loosely woven material (as gunny sack) could, perhaps, 
be used instead of the wire basket. A perforated tin 
vessel is, in some respects, preferable to any vf the above. 

"Now dip the basket of seed in the first vessel; 
after a moment lift it ; and, when the water has for the 
most part escaped, plunge it into the water again, repeat- 
ing the operation several times. The object of the lift- 
ing and plunging, to which should be added also a rotary 
motion, is to bring every grain in contact with the hot 
water. Less than a minute is required for this prepara- 
tory treatment, after which plunge the basket of seed 
into the second vessel. If the thermometer indicates 
that the temperature of the water is falling, pour in hot 
water until it is elevated to 132^-. If it should rise 
higher than 135, add small quantities of cold water. 
This will doubtless be the most simple method of keep- 
ing the proper temperature, and requires only the addi- 
tion of two small vessels, one for cold and one for boil- 
ing water. 

"Steam, conducted into the second vessel by a pipe 
provided with a stopcock, answers even better, both for 
heating the water and elevating the temperature from 
time to time. 

"The basket of seed should, very shortly after its 
immersion, be lifted, and then plunged and agitated in 
the manner described above ; and the operation should 
be repeated eight or ten times during the immersion, 



THE BUNT, OR STINKING SMUT 197 

which should be continued fifteen minutes. In this way 
every portion of the seed will be subjected to the action 
of the scalding water. Immediately after its removal 
dash cold water over it or plunge it into a vessel of cold 
water, and then spread out to dry. Another portion can 
be treated similarly, and so on until all the seed has been 
disinfected. Before thoroughly dry the seed can be sown ; 
but it may be thoroughly dried and stored if desired. 

" The important precautions to be taken arc as fol- 
lows : (1) Maintain the proper temperature of the 
water (132^ F.), in no case allowing it to rise higher 
than 135, or to fall below 130. This will not be diffi- 
cult to do if a reliable thermometer is used, and hot or 
cold water be clipped into the vessel as the falling or ris- 
ing temperature demands. Immersion fifteen minutes 
will not then injure the seed. (2) See that the volume 
of scalding water is much greater (at least six or eight 
times) than that of the seed treated at any one time. 
(3) Never fill the basket or sack containing the seed 
entirely full, but always leave room for the grain to move 
about freely. (4) Leave the seed in the second vessel of 
water fifteen minutes." 

Literature. This smut has been very often treated 
of during recent years. Articles concerning it may be 
found as follows : Bulletin No. 1, North Dakota Exper- 
iment Station ; Bulletin No. 28, Indiana Experiment 
Station ; Bulletins and reports Kansas Experiment 
Station, 1890-1891. 



198 



I'TN<!I AND FUNIMCIDKS 



The Loose Smut 

Ustilago tritiei 

The loose smut of wheat is ut once distinguished 
from the bunt by the fact that the spores are not con- 
cealed, so that usually the kernels 
resemble masses of black powder. 
Such a head is represented at Fig. 81, 
a, engraved after Kellerman and Swin- 
gle. The powder soon blows away, 
leaving the bare chaff and stem, b. 
This disease is found, to a greater <>r 
less extent, wherever wheat is grown, 
but is seldom as destructive as the 
bunt. No successful method of com- 
bating it has yet been found. A good 
discussion of it occurs in the second 
report of the Kansas Experiment Sta- 
tion, 1889, pp. 261-268. 

It was formerly supposed that the 
loose smut of oats was the same as that 
of wheat ; but recent observations indi- 
cate that the fungi causing the two 
maladies are different species, and that 
they cannot pass from one plant to the 
other. Professor Bessey has shown 
that part of the heads of given stools 
of wheat may be affected with loose 
smut, and part be healthy. 




WHEAT SMUT. 



The Wheat Scab 



Fusisporium culmorum 

This is a peculiar disease which attacks the heads 
and kernels of wheat. It is usually first noticed just as 
the heads are beginning to turn, when an examination of 
infested fields shows that with a portion of the heads the 



THE WHEAT SCAB 



199 




FIG. 82. 

SPORES OF WHEAT 
SCAB. MAGNIFIED. 



upper or lower half has prematurely whitened, leaving 
the rest green, the whitened part having on many of the 
glumes a more or less distinct pink or orange covering 
of the mycelium and spores of the fungus. Under ^a 
high power of the microscope this 
fungus is seen to be composed of long 
curved spores, as shown in Fig. 82. 
According to the botanists, it is a 
species of Fusisporium. The kernels 
attacked by the fungus become mere 
shells, covered inside and out with 
mycelium (Fig. 83) and in passing 
through the thresher they are blown 
away with the chaff. The yield is 
sometimes greatly decreased. In 
1890 I saw a field of one hundred 
acres in Madison County, Ohio, con- 
sidered the finest wheat field in the 
county, which was expected, shortly before harvest, to 
yield thirty-five to forty bushels per acre, so severely 
attacked by the disease that the yield was reduced to 

eight bushels per acre. 
Two other fields, one of 
twenty-five and the other of 
fifty acres, were shrunken 
in yield at least one-third, 
from the same cause. The 
fungus apparently gains 
access to the tender, unde- 
veloped kernel, sapping its 
life and sending down feed- 
ED.BY SCAB. ers into the main axis of 

the head on which the kernel and inclosing chaff are 
borne. The functions of this part of the plant soon 
become locally deranged, and, in consequence, the sup- 
ply of nutriment for the portion of the head above the 




FIG. 83. WHEAT KERNELS AFFECT- 



200 FUNGI AND FUNGICIDES 

affected part is cut off, causing it to stop growing and 
lose its green color. As the fungus develops it produces 
great numbers <>f .-pores, which give ihe pinkish color to 
the affected parts. As a rule, the di>ease is woix- on 
weak-growing varieties, and those fields which are sowed 
latest. Consequently, vigorous growth and early blos- 
soming are thought to be the chief safeguards against 
the malady. 

The Wheat Rust 

Pucdnia rubigo-vera 

Probably no disease of cereals causes a greater loss 
to American farmers than the rust of wheat. It appears 
to be known wherever wheat is grown, and is often 
responsible for the destruction of a large percentage of 
the crop. It has, until recently, been quite generally 
assumed, by botanists and others, that the fungus caus- 
ing wheat rust in America is the same species that 
causes it in Europe a species known to science as Puc- 
dnia graminis but it has lately been shown that our 
common rust is often an entirely different fungus, whose 
Latin name appears above. The European species passes 
one stage of its existence upon the barberry, causing the 
familiar cluster-cups, but the other fungus has no con- 
nection with the barberry. It has a first, or cluster-cup 
stage, which is passed on certain plants belonging to the 
Borage family ; and has also two different stages upon 
wheat. The first of the wheat stages but the second 
in the life-cycle of the fungus is the red rust stage, 
called, by botanists, the uredo stage. It is in this con- 
dition that the fungus is most destructive. Later in 
the season an entirely different kind of spore is produced 
the so-called teleuto-spore which forms the third 
stage of the fungus. But recent investigations have 
shown that the second, or uredo-stage, is able to survive 



THE WHEAT RUST . 201 

the winter and reproduce itself indefinitely, so that it is 
probable that, in many cases, this stage of the fungus is 
all that is necessary to explain its continued existence. 
All farmers know with what marvelous rapidity 
wheat rust spreads, if wet weather occurs shortly before 
harvest. It is a disease for which, as yet, no successful 
remedy has been found. Full knowledge of its life-his- 
tory is yet wanting, and, possibly, when more is known, 
successful preventives may be suggested. Early ripen- 
ing varieties are less liable to damage than others. The 
fungus often passes the summer on volunteer wheat, 
hence this should be destroyed. A discussion of the 
life-history of the European wheat rust may be found in 
W. G. Smith's '* Diseases of Field and Garden Crops" 
(pp. 147-207). The American rust is treated of in Bul- 
letin No. 26, Indiana Experiment Station ; Bulletin No. 
5, Minnesota Experiment Station ; and in various other 
periodicals. 



FUNGI AFFECTING INDIAN CORN 



The Corn Smut 

Ustilago zece-mays 

The smut of Indian corn is one of the most widely 
distributed and generally known of the fungous diseases 
of plants. It probably occurs wherever this crop is 
extensively grown, and it has been known for many 
years. The amount of injury it does varies greatly, but 
has seldom been accurately determined. In the report 
of the Tenth Census of the United States, Professor 
Brewer writes that he has heard of instances in which 
the damage was estimated as high as sixteen per cent., 
although he had, himself, never seen a field which was 
injured to the extent of one per cent. Professor Bessey 
reports that in a garden patch where sweet corn had 
been grown for several successive years, sixty-six per 
cent, of the crop was destroyed by smut one season. 
The general average, the country over, however, prob- 
ably does not exceed one or two per cent. 

Although corn smut usually infests the ears of the 
plant, it is occasionally found upon tassel, stem and 
leaves. On the ear it first appears as a white, malformed 
mass, representing either the whole ear or a portion of 
the kernels (Fig. 84). The whiteness gradually becomes 
darker, finally changing into a brownish-black powdery 
mass, consisting of millions of the minute spores or 
reproductive bodies of the fungus. On the tassels the 
swellings are not so large, and on the stem and leaf 
their size varies greatly. 

202 



THE CORX SMUT 



203 



When one of these spores comes in contact with a 
drop of water it soon germinates by sending out a little 
tube, which has the power of developing certain second- 
ary spores, called sporidia. The sporidia themselves 
have the power of germinating, under favorable condi- 
tions, and in a liquid containing sufficient organic mafc- 




FIG. 84. PA1JT OF SMUTTKI) EAK OF C'ORX. 

ter for their nourishment (manure water, for example), 
they can continue growing and multiplying for an indef- 
inite period. It is believed, by some authors, that these 
sporidia may develop in the barnyard, from the spores 
which find their way to the manure pile, and be carried 



'MM 



l-TMil AND lTN-<;irlI)KS 




to the field with the manure, finally infecting the plants 
but this has not yet been definitely determined. The 
observations of Kuhn indicate that the germinating 
mycelium penetrates the very young corn plant at the 
root node and the first formed joint, and that after the 
corn gets well started the danger of infection by smut is 
passed. It has generally been supposed that the sp< 
adhered to the seed, and caused infection; but recent 
experiments at the Kansas Experiment Station in 
~hich corn kernels were rolled in smut spores, without 

increasing the amount of 
smut in the resulting crop 
throw so much doubt upon 
this assumption that Pro- 
fessor Kellerman thinks that 
"further investigation is 
necessary in order to deter- 
mine the mode of infection,"' 
adding that this is "a point 
that must be settled before 
we can hope to employ ra- 
tional methods for the pre- 
vention of this annoying and destructive pest." 

It seems pretty well proven, however, that the smut 
can exist in the soil from year to year, and infect suc- 
ceeding crops. The following experience, related by 
Professor Bessey, as occurring in Iowa a few years ago, 
shows this: "One season a piece of land, including 
about three-fourths of an acre, was planted with sweet 
corn for table use. Some smut made its appearanc* 
first year, but it was all allowed to fall back to the 
ground. None of the stalks were removed, but all were 
plowed under, and the second season the ground was 
again planted with sweet corn, for table use as before. 
This time the smut was remarkably abundant, but again 
it was all allowed to fall upon the ground, and was 




FIG. 85. SMUT SPORES GERMINAT- 
ING AND FORMING SPORIDIA. 



THE CORN SMUT 205 

plowed under with the stalks. The third season the 
ground was planted as before, and this time fully two- 
thirds of the ears were affected with smut. In fact, the 
smut was so abundant that but little corn was gathered, 
and the crop was practically abandoned. The ground 
was found to be now so filled with smut as to unfit it 
for further use for corn, and it was consequently assigned 
to other uses. The lesson is very obvious. Smut left 
on the ground will produce smut the next year." 

After the mycelium of the smut fungus has pene- 
trated the corn plant it grows along with the latter, 
pushing its way through the tissues of the stem, and 
finally developing extensively, by means of many 
brunches, in the ear or tassel. From this mass of 
branches the spores develop, the latter absorbing so 
much of the substance of the former that the mass of 
mycelium becomes gelatinous, and finally disappears, 
leaving in its place the familiar blackish, powdery mass 
of spores. Up to the time of maturity the smut mass is 
surrounded by a dull white membrane, which finally 
bursts and allows the spores to escape. 

Many farmers believe that corn smut is very injuri- 
ous to cattle when eaten by them. Cases of death at- 
tributed to this cause are not uncommon ; but feeding 
experiments made by Professors Gamgee, Henry, and 
others, indicate that the amount of smut cattle are likely 
to eat, under ordinary circumstances, would do little, if 
any, injury. The only plant besides Indian corn upon 
which this kind of smut is known to develop, is a coarse 
grass called Teosinte, which is sometimes used as a for- 
age plant in the Southern States. 

Microscopic Characters. The spores of corn 
smut are so minute that it has been estimated that from 
30,000 to 50,000 of them will adhere to the moistened 
head of a common pin ; that 25,000 of them, laid side 
by side in a straight line, would measure an inch ; and 



Jill! FU.NCJI AND Fl N(iK [DBS 

that single cubic inch of smut would contain more 
than 15,000,000,000 of them. The dry spores are glo- 
bose, and brovvnish-bljick. wil.li the outer surface thickly 
studded with elevated points. The method of germina- 
tion and of the formation of sporidia is well illustrated 
at Fig. 85. The mycelium is whitish, and the tips of 
the threads are able to penetrate the cells of the corn 
plant. The cells are also penetrated by the haustoria, 
or suckers from along the mycelial threads. 

Treatment. In the light of our present knowl- 
edge, measures looking toward the lessening of loss from 
smut must be largely of a preventive nature. As Pro- 
fessor Kellerman has pointed out, we must know the 
mode of infection of the corn plant by smut before we 
can be sure of the most rational remedy. The fact, 
however, that smut thrown or left upon the ground pro- 
duces the disease in succeeding crops, and the apparent 
probability that infection may be brought about by the 
distribution of the spores, or sporidia, in manure, indi- 
cate (1) that rotation of crops should be practiced, and 
(2) that as much of the smut as possible should be 
destroyed before it comes to maturity. It will pay the 
careful farmer to cut out and burn, or bury, the smut 
balls before the membrane covering them bursts and 
allows the spores to escape. At the time of husking, all 
smut masses that have escaped detection should also be 
disposed of. ""\Vhere domestic animals are allowed to 
eat smut in the field they become the carriers of the 
spores, and their droppings, filled with the still living 
spores, become the centers of ^infection. No animal 
should be permitted to eat smutted corn, even though 
the owner be convinced of its harmlessness to the animal 
itself. The harm lies in the distribution of the spores, 
which are little, if at all injured, by passing through the 
alimentary canals of animals." (Bessey.) 

The soaking of seed corn in copper sulphate solu- 
tions to destroy the adhering smut spores, has frequently 



THE INDIAN CORN RUST 207 

been recommended, but the failure of Professor Keller- 
man's experiments, in attempting to increase the amount 
of smut by rolling the seed in the spores, indicates that 
this is hardly worth while, especially as the copper sul- 
phate soaking has the effect of diminishing the vitality 
of the seed. If treatment of this kind were desirable, it 
would be better to adopt the hot water method used to 
destroy the smut of oats and wheat. From the fact that 
the smut enters the plant when very young, we should 
hardly expect that spraying the growing corn with the 
Bordeaux mixture, or other fungicides, would do any 
good ; and recent experiments confirm this supposition. 
Literature. An excellent general account of corn 
smut, by Professor A. B. Seymour, may be found in 
the 1887 report of the Department of Agriculture 
(pp. 380-389). 

The Indian Corn Rust 

Puccinia maydis 

The disease of Indian corn known as rust has at" 
tracted comparatively little attention from American 
farmers, and, so far as its injuries are concerned, it is, 
indeed, of minor importance. It is fortunate that this 
is the case, for, as yet, no successful method of combat- 
ing it has been suggested. 

Corn rust is quite similar, in character and appear- 
ance, to the familiar red rust of wheat and oats. It 
usually appears about midsummer, in the shape of small, 
brownish, dust-like blotches on the surface of the corn 
leaf. These dust-like patches, or pustules, consist of 
the summer spores of the fungus ; the spores are of a 
rich yellowish brown color, and are easily blown away by 
the wind. Toward the end of summer these brownish 
spores are replaced by blackish ones, so that the pustules 
then assume a blackish appearance. These dark-colored 



208 



FUNGI AND FL T XGIC1JH> 



spores are the winter spores, and are very different in 
structure and appearance from the summer spores. The 
two kinds are produced from the same mycelium, and at 
certain seasons they may be found intermingled in the 
same mass, or pustule. This fungus usually only devel- 
opes after the corn has gotten well along in its growth, 
so that the effect of its injury is less than if the very 




FIG. 86. CORN BUST, 
a, Section of leaf showing teleuto-spores; 6, uredo-spores; c, teleuto-spores. 

young plants were attacked. Hence it seldom assumes 
a serious economic importance. 

The brown summer spores (called by botanists uiedo- 
spores) are nearly spherical, with the outer wall thickly 
studded with minute pointed projections (Fig. 86 t>). 
They are about one-one thousandth of an inch in diam- 
eter, and are borne on slender stalks arising from the 



THE BACTERIAL DISEASE OF CORK 209 

mass of the mycelium, from which they readily separate. 
They serve to spread the disease during a limited time 
in summer, but are supposed not to survive the winter. 
The blackish winter spores (called by botanists the 
teleuto-spores) are decidedly different in structure and 
appearance from the others. A cross section of a corn 
leaf through one of the blackish pustules is represented 
at , Fig. 86. As will be seen, the spores are borne on 
stout stalks, to which they remain attached, c. The 
spores themselves are so divided by a partition across the 
middle that they are practically double ; each part can 
germinate independently of the other. These spores 
survive the winter. 

Treatment. As already intimated, no practical 
remedy is known for this disease ; and, fortunately, 
none as y<3t is seriously needed. A more extended dis- 
cussion of this malady is published in the 1887 report of 
the Department of Agriculture (pp. 389-391). 

The Bacterial Disease of Corn 

In 1889 Professor T. J. Burrill, of the University 
of Illinois, announced the discovery of a peculiar malady 
of Indian corn, which he had proven was due to the 
presence of bacteria. The disease was then prevalent 
over a considerable area in Illinois, and investigations 
since have indicated that it does much damage often 
not understood, or else attributed to other causes over 
u large portion of the corn-growing region of the West. 
As the disease is an obscure one, not easily recognized or 
described, Professor BurrilPs account of its appearance 
is quoted below at length. 

External Manifestations. " The first indication 
of this disease in a field of corn, as noticed in ordinary 
observation, is the dwarfed condition of the young 
plants. This commonly occurs in spots of various sizes, 
from a few square rods, to an acre or more, and often, 
14 



210 ir.Mii A .vi) 



though by no means always, on soil of a character some- 
what different from the rest of the field. It seems hard 
to designate what special condition or quality of soil is 
most usually associated with the disease ; but, upon the 
whole, it is found in the rich spots, rather than in those 
of the poorer quality. In many cases it is upon the 
lowest ground, whether or not water has temporarily 
stood in the hollows. The most definitely bounded area 
noticed was upon a spot which had, until the year previ- 
ous, been too wet for tillage, but which had been tile 
drained and broken up, the sod having rotted. 
But ordinarily there are no such definite borders to the 
infected areas, and often nothing whatever to suggest a 
reason for their peculiar distribution. 

"Upon closer observation it is found that young 
diseased plants, besides being smaller than the healthy 
ones, are uniformly yellowish in color, the lowest leaves 
showing worst. As death overtakes these leaves, they 
apparently succumb by a general decline from the 
healthy state, and rarely die, and wither chiefly at the 
ends and margins as in some other cases. When some 
of the affected plants are pulled from the ground they 
are found to give way too easily, in consequence of the 
death, to a greater or less extent, of the oldest and low- 
est roots. In anything like severe cases at least one-half 
the roots always the lowest are injured, and usually 
dead. The bottom portion of the stalk is likewise 
affected, and will be found dead or dying. If split lon- 
gitudinally through the middle, the inner tissue of this 
lower part is seen to have a uniform dark color ; and a 
similar discoloration, gradually becoming less and less 
pronounced, appears in the next succeeding nodes, or 
joints, while the spaces between them (internodes) are 
seemingly healthy. On the surface, when carefully 
freed from dirt, brownish, corroded spots can- be found, 
sometimes strictly bordered, again diffusely spreading. 



THE BACTERIAL DISEASE OF CORN 211 

Sometimes masses of semi-transparent, rather firm, gel- 
atinous material are found upon these external corrosions. 

"After midsummer, especially, the disease becomes 
apparent through discolorations of the portions of the 
leaves called the sheaths, which closely invest the stalk. 
Thjse leaf -sheaths become variously spotted, as observed 
from the exterior. Sometimes the watery-brown por- 
tions are mere specks ; sometimes large irregular patches, 
and of all grades between these extremes. The discol- 
orations become brown, of a half-rotten appearance. 
Occasionally there is a little reddish color, more often 
bordering the brown. If, now, these affected leaves are 
stripped from the stalk, it will be found that the evi- 
dence of injury is much more conspicuous on their inner 
side. The injured patches are larger, have a more 
watery appearance, and sometimes are more or less 
smeared with the same gelatinous substance previously 
mentioned as occurring on the diseased stem below the 
ground ; but here on the leaf-sheaths it is usually spread 
in a thinner coating, or layer, instead of in round masses. 
This infection of the leaf-sheaths evidently comes later 
in the season than the first noticed form of the disease 
on the roots. It seems also to be evenly distributed 
through the field, and to occur upon large as well as 
small plants. 

"Finally, the ears are, at least occasionally, affected. 
Externally, the appearance of the outer husks is like 
that of the diseased leaf-sheaths. Internally, in the 
worst stage, the whole ear husks, which should be still 
green, young cob and kernels, and the mass of "silks" 
is reduced to a moist state of corruption, though not 
ill-scented. The parts lose their normal rigid, or turgid 
quality, appear as if wilted, and are packed closely 
together, if not actually adhering by the gummy exuda- 
tion from the tissues. Very often these ears subse- 
quently become moldy, penetrated through and through 



212 



FUNGI AND FUNGICIDES 



by a close, very white, felt-like fungus. Possibly this 
fungus sometimes makes its inroads into the ear without 
the bacteria as forerunners ; but from present knowledge 
it seems probable that it is a secondary intruder. These 
moldy ears are, in certain seasons, very numerous, and 
are readily recognized by the husker, as 'well as by the 
buyer, when the loads are sent to market." 

Microscopic Characters. When placed under a 
very high power of the microscope, the juices from 
affected portions of corn plants are seen to be swarming 
with minute bacteria. These bacteria, when magnified 




FIG. 87. BACTERIA OF CORN DISEASE. 

nearly three thousand times, resemble Fig. 87. Each 
individual measures less than one-twenty-five thousandth 
of an inch in length. They frequently form jelly-like 
masses on the inside of the leaf, these masses consisting 
of the bacteria themselves held together by the mucilag- 
inous substance they exude. 



THE BACTERIAL DISEASE OF CORN 213 

Possible Effect on Cattle. Investigations made 
in Nebraska; by Dr. F. S. Billings, indicate the proba- 
bility, and, in the opinion of Dr. B., the certainty, that 
when cattle eat corn affected by this disease the germs 
present may cause the illness, and sometimes the death 
of the animals. He calls it the "Cornstalk Disease in 
Cattle," and concludes an elaborate report of his investi- 
gations with this statement: "When cattle become 
unaccountably ill immediately after having been turned 
into a stripped cornstalk field, and that illness is accom- 
panied by the phenomena previously detailed, it may be 
taken for granted that it is this corn-fodder disease, and 
no other." 

Treatment. No method of preventing the disease 
in corn has yet been suggested, except that of crop rota- 
tion, and so little is known of what other plants are 
attacked by the same germs that this is merely a sugges- 
tion. Care should be taken that cattle are not turned 
into fields of corn that have patches affected by the dis- 
ease ; at least not until all such patches have been cut 
and the fodder burned. 

Literature. An account of Professor BurrilPs 
investigations may be found in the Proceedings of the 
Tenth Meeting of the Society for the Promotion of Ag- 
ricultural Science (1889, pp. 19-27), and in one of the 
earlier Bulletins of the Illinois Experiment Station. 
Dr. Billings' investigations are reported in the Bulletin 
of the Nebraska Experiment Station (Nos. 7-10, pp. 
165-210; June, 1889). 



FUNGI AFFECTING BROOM CORN AND 
SORGHUM 



The Sorghum Blight 

Bacillus sorgfii 

This disease is caused by bacteria, and so is some- 
what similar to the bacterial disease of corn already dis- 
cussed. It occurs upon both sorghum and broom corn, 
and is especially characterized by the red markings it 
produces upon affected plants. Its nature was first 
worked out by Professor T. J. Bur rill, who gives the 
following description of the external manifestations of 
its presence : 

"Sometimes the appearance of injury is noticeable 
upon young plants. They grow very slowly, are slender 
and yellowish in color, and are easily pulled from the 
ground. The lower leaves die, having previously shown 
discolored (yellow or red, mostly the latter) patches on 
various parts of their surface. Not unfrequeutly these 
conditions prevail in special areas of the field ; perhaps 
several acres, not apparently different in composition of 
soil, condition of drainage, etc., will have throughout 
their extent this dwarfed and sickly crop, while the rest 
of the plantation remains healthy and vigorous. More 
often the evidence of disease appears, to a greater or less 
extent, over the entire field, all, or an exceedingly varia- 
ble proportion of the plant suffering. Not unfrequently 
stalks, four or five feet high, can be lifted with ease from 
the soil, the foots being mostly dead and rotten. 

"Upon the serial parts the conspicuous evidence of 
disease, aside from the smaller size of affected plants, is 

214 



THE SOKGHUM BLIGHT 215 

the red-blotched leaves and leaf-sheaths. The latter are 
particularly spotted at the upper portion, just below the 
ligule. If they are stripped from the stalk the carmine 
coloration is seen to be conspicuously brilliant inside, 
and often extending over a large area of the interior sur- 
face of the sheath. On the leaves themselves the spots 
are usually more numerous along the mid-veins. The 
stalks are usually not locally affected until late in the 
season, when they, too, show evidence of the disease by 
the appearance of red or rusty spots. On the " brush" 
of broomcorn similar discolored patches are to be ob- 
served, and these directly injure the product. The 
rusty, corroded places may be frequently found on the 
brush of the manufactured brooms. 

"The diseased roots also turn red but soon decay, 
and, of course, lose the bright color. The oldest roots 
die first, and, as new ones are successively emitted from 
the base of the stem in the order commonly occurring in 
these plants, they, in turn, become successively affected 
and perish. This is why the plant yields to so slight a 
pull, while healthy ones resist a vigorous effort. Upon 
close examination it is evident that the exterior part of 
the roots or cortex is the portion in which the disease is 
resident, the woody fibers of the interior remaining for a 
long time unchanged, except through natural decay 
after the death of the whole root. But the woody part 
is stained from contact with the external layer." 

It has been conclusively shown, both by Professor 
Burrill, and by Messrs. Kellerman and Swingle, that 
this disease is due to a distinct species of bacteria, re- 
quiring a high microscopic power to be seen, and special 
skill and training to be successfully studied. When 
highly magnified these bacteria bear a general resem- 
blance to Fig. 87. 

Treatment. Rotation of crops seems to be the 
best method of preventing the development of this dis- 



216 



FUNGI AND FUNGICIDES 



ease. According to Professor Burrill, "crops are some- 
times injured in the way described on land not previ- 
ously planted with sorghum or broomcorn ; but the 
danger is invariably less," and "field practice has given 
excellent demonstration of this system of management." 
It is also advisable to burn refuse stalks and stubble, so 
fi -'r as is practicable. 

Literature. Professor Burrill's article was pub- 
lished in the Proceedings of the Eighth Annual meeting 
of the Society for the Promotion of Agricultural Science 
(1887, pp. 30-36). Messrs. Kellerman and Swingle 
have published their results in the report of the Kansas 
Experiment Station (1888, pp. 281-302). An additional 
note occurs in the Journal of Mycology for December, 
1889 (v. 5, pp. 195-199). 

The Grain Smut of Sorghum 

Ustilago sorghi 

The individual seeds of sorghum heads are some- 
times attacked by smut. Such seeds become greatly 
swollen especially lengthwise and consist of a grayish 
outer membrane surrounding a mass of dark powder. 
The disease is illustrated and briefly described by Pro- 
fessor Kellerman, in Bulletin No. 23 of the Kansas Ex- 
periment Station. 

The Head Smut of Sorghum 

Ustilago reiliana 

This disease differs from the last in that the whole 
head of the sorghum stalk is usually diseased, being 
"converted into a large, continuous, or lobulated mass 
covered with a white membrane. The latter soon rup- 
tures and exposes the black, powdery mass of spores." 
This fungus is discussed and figured in the bulletin 
above mentioned. 



FUNGI AFFECTING ALFALFA 



The Alfalfa Leaf-blight 

Cercospora helvola var. medicaginis 

This disease has been studied by Professor F. D. 
Chester, of Delaware, who reports that it "shows itself 
upon the leaf as sub-circular, or elliptical spots of a 
smoky brown, or almost black color, equally visible upon 
both sides, and vary- 
ing from one-six- 
teenth to one-thirty- 
second of an inch in 
diameter. The spots 
are without well-de- 
fined borders, which, 
when closely exam- 
ined, are somewhat 
irregular, shading in- 
distinctly into the 
surrounding leaf tis- 
sue. Spots coales- 
cing cause the leaf to 
turn yellow and brown, completely destroying it." 
The same fungus is believed, occasionally, to attack 
the red clover and scarlet clover, although it is seldom, 
if ever, seriously destructive to these crops. The myce- 
lium threads of the fungus push about between the cells 
of the leaf, absorbing their contents, and causing the 
discoloration of the foliage. When ready to fruit, the 
threads develop abundantly at certain points just beneath 

'317 




FIG. 88. ALFALFA BLIGHT FUXGUS. 
a, Spore; 6, section of leaf. Magnified. 



218 



FUNGI AND FUNGICIDES 



the epidermis of the leaf, and then push out several 
stalks, on the ends of which the spores are produced. 
The latter (Fig. 88 a) are long and slender, and divided 
by several transverse partitions. They germinate when 
on moist alfalfa leaves, by sending out a slender thread, 
which penetrates the skin of the leaf and starts the 
fungus anew. 

Treatment. Upon this point Professor Chester 
says : "In case it should be necessary seriously to com- 
bat this difficulty, the writer would advise that all dis- 
eased patches or areas be cut and burned, or composted 
with an excess of lime." 

Literature. The only article of importance con- 
cerning this disease yet published is the one above re- 
ferred to, which may be found in the Second Report of 
the Delaware Experiment Station (1889, pp. 95-97). 
Another disease of alfalfa is briefly described in the 
same connection, and another in the report for 1890. 



FUNGI AFFECTING CLOVER 



The Clover Rust 

Uromyces trifolii 

Although this disease has been known in Europe as 
a clover enemy for a long time, it has only recently been 
noticed in this country. It is now widely distributed, 
however, occurring from Connecticut, in the east, to 




FIG. 89. 

a, White clover leaf showing aecidium stage; 6, red clover leat showing uredo 

stages. 

Colorado, in the west. It is occasionally so abundant 
as to injure seriously fields of red clover. Leaves affected 
by the disease are more or less thickly covered with 
well-defined, oblong, brown powdery spots, as shown in 
Fig. 89. 

319 



220 



I I N(il AM) FUNGICIDES 



Like various other members of the family of rusts 
to which this fungus belongs, it exists in three distinct 




FIG. 90. CLOVER RTJST. 

c, Cluster-cups and reciclium spores; <7, uredo spores ;/, uredo pustule on clover 
leaf; e, teleuto spores; #, cross-section of stem showing mycelium between 
cells; also two teleuto spores and one uredo spore. 

successive stages. Early in the season it appears prin- 
cipally upon white clover plants in the so-called acid- 



THE CLOVER BUST 221 

turn stage. It affects both the leaves and stems, produc- 
ing cup-like swellings, which are filled with orange 
colored spores. A white clover leaf attacked by this 
stage of the fungus is shown in Fig. 89 a, while at c, 
Fig. 90, may be seen two of the cluster-cups magnified, 
and some of the orange colored spores still more enlarged. 
These orange spores are blown to other clover plants, 
especially red clover, where they germinate and send 
their little tubes into the leaf tissues. These tubes start 
the mycelium which develops between the leaf cells for 
some time before any external indication of its presence 
occurs. Then it produces, at certain places just beneath 
the outer skin of the leaflets, numbers of small reddish- 
brown spores, which finally rupture the skin (as seen in 
Fig. 90/), and are set free. When magnified (d) these 
spores are shown to have their outer surfaces studded 
with minute pointed tubercles. This is the second, or 
uredo stage of the fungus ; these spores are called uredo- 
spores. After these are mostly blown away presumably 
to start the disease in new situations there is produced 
from the same mycelium, and in the same spots, the third 
form of spores called the teleuto-spores (e). These are 
supposed to carry the fungus through the winter, although 
it is probable that it also passes the winter in the myce- 
lium in white clover plants. 

Treatment. According to Miss J. K. Howell, of 
the Cornell University, to whom we are indebted for 
much of our knowledge of this disease, the early crop of 
red clover is not likely to be injured by rust. In conse- 
quence, she makes the following suggestions as to rem- 
edies : "As the second crop is likely to suffer greatly if 
the midsummer is cool, and as clover becomes a valuable 
fertilizer when plowed in, the fields should be carefully 
watched in such seasons, and the crop might be plowed 
under to advantage. Burning the clover fields in the 
fall would probably have some effect in checking the 



FUNGI AND FUNGICIDES 

spread of the disease during the next season ; but the 
application of fungicides seems impracticable." 

Literature. The most complete account of this 
disease in American literature is that of Miss Howell, 
referred to above, which is found in Bulletin 24 of the 
Cornell Experiment Station. Professor Pammel has 
discussed it in Bulletin No. 13 of the Iowa Station ; and 
various notes concerning it have been published elsewhere. 




INDEX 



Page 

Alfalfa, Fungi affecting, .... 217 

leaf-blight, ..... 217 

Apple, Fungi affecting, .... 27 

bitter rot, ..... 33 

powdery mildew, .... 30 

rot, ..... 33 

ripe rot, . . . 33 

rust, ..... 36 

scab, . . . .2,27 

twig blight, ..... 39 

Ascochyta petunias, .... 125 

Bacillus soryhi, ..... 214 

Bean, Fungi affecting, . . . 129 

anthracnose, ..... 129 

blight, . 132 

pod spot, ... . 129 

rust, . . 132 

Beet, Fungi affecting, ..... 135 

leaf-spot, . . . . 136 

rust, . . . . .135 

Bordeaux mixture, . . . . 15 

and arsenites, . . . . .20 

Broom corn, Fungi affecting 1 , .... 214 

Cabbage, Fungi affecting, .... 138 

club root, .... 138 

Carbonate of copper, . . . . .18 

Carnation leaf-spot, .... 121 

rust, ..... 120 

Catalpa leaf -spot, . . . . Ill 

Cauliflower, Fungi affecting, .... 138 

Celery, Fungi affecting, .... 144 

blight, . . . . .144 

leaf-blight, .... 146 

soft-rot, . . . . .149 

Ceratocyslis fonbriata, . .172 

223 



224 



FUNGI AND FUNGICIDES 



Cercospora anyulata, 

" (i/iii, 

" hetico/a, 

" //////, 

" reset Ice, 

Cherry, Fungi 

brown rot, 

black knot, 
Clii'stcr spraying cart, 
f 'ladosporium carjH>j)/tiln/it, 
Clover, Fungi affecting, . 

rust, 
Cceoma niteris, 



" x/>inaccce, 

Conidia, 
Copper arsenic solution, . 

chloride, 

Cotton wood leaf-rust, 
Cucumber, Fungi affecting, 
Currant, Fungi affecting, 

anthracnose, 

leaf-spot, 

Cylindrosporium padi, 
Damping-off fungus, 
Eau celeste, 

Entomosporium maculatwn, 
Flowers, Fungi affecting, 

carnation rust, 
" leaf -spot, 

hollyhock rust, 

mignonette disease, 

petunia blight, 

verbena mildew, 
Fungi, losses due to, 

methods of studying, 
" " distribution, 
" " preventing, 

parasitic, 
Fungicides, application of 

the important 

and insecticides 

use of 
Fusicladium tie ndrit ic uni, 

pyrinum, \ 



111 

136 

217 

128 

66 

i;<; 

66 

23 

D2 

219 



177 
7 

20 

lit 

112 

160 

91 

92 

9] 

68 

182 

17 

11, -17 
119 
128 
121 
119 
128 
125 
124 
1 

11 
11 
12 
2 
21 
14 
20 
14 
27 



ItfDEX 225 



Fusisporium culmorum, .... 198 

Glceosporium fructigenum, . . . . .33 

nernsequum, . . . . 113 

ribis, ..... 92 

venetuni, .... 97 

Gooseberry, Fungi affecting, . . . .91 

leaf -spot, . . . . 01 

mildew, . . . . .93 

Grape, Fungi affecting, .... 79 

anthracnose, . . . . .87 

black rot, . . . . 79 

brown rot, . . . . .82 

downy mildew, .... 82 

powdery mildew, . . . . .85 

Gymnosporangium, .... 36 

Hollyhock rust, . . . . .119 

Indian corn, Fungi affecting, . . . 202 

bacterial disease, ..... 209 

rust, .... 207 

smut, ..... 202 

Knapsack sprayer, .... 22 

Loestadiu bidwelli, . . . . .79 

Lima bean mildew, .... 133 

Mdcrosporium xolani, . . . . .165 

Maple leaf -spot, . . . . 113 

Mc/uni/txord populina, . . . . .112 

Melons, Fungi affecting, . . . . 160 

bacterial blight, . . . . .160 

leaf-spot, . . . . 163 

mildew, . . . . .160 

Micrococcus amylovorus, .... 3'), 44, 51 

Mignonette disease, . . . . .123 

Modified eau celeste, . . . . . 18 

Monilia fructigena, .... 2, .",(>, 66, 73 

Mushrooms, .... 4 

Nozzles, ..... 22 

Oats, Fungi affecting, .... 187 

loose smut, . . . . .187 

rust, .... 193 

Oldium erysiphioides, ..... 124 

Onion, Fungi affecting, .... 150 

mildew, . . . . .150 

s-inut, . . . 2, 152 

spot diseases, . ... 157 

Qo$pora acdbies t .... 168 

15 



226 



FUNGI AND FUNGICIDES 



Parasitic fungi, 
Peach, Fungi affecting, 

brown rot, 

leaf -curl, 

rosette, 

yellows, 
Pear, Fungi affecting, 

blight, 

leaf-blight, 

seal), 
Pcronoxpora, 

tffiua t 

schleideniana, 



Petunia blight, 
Phyllosticta acericola, 

" catalpce, 

PhraffmuKwn mucronatuin, 

" specioswn, 

Phytopliora phaseoli, 
Plasmodiophora brassica', . 
Plasmopara cubensis, 
Ploicriyhtia morbosa, 
Plum, Fungi affecting, 

black knot, 

brown rot, 

fruit scab, 

fruit spot, 

leaf-blight, 

leaf rust, 

pockets, 

Podosphcera oxyacanthcc, 
Potato, Fungi affecting, . 

bacterial blight, 

downy mildew, 

early blight, 

late blight, 

leaf -spot, 

scab, 

Potassium sulphide, 
Puccinia malvacearum, 

" may 'd 'is, 

" pruni-spinoncc, 

" rubiyo-vera, 
Pythiwn De Baryanum, 



67 
7:5 
67 
78 

41 
44 
11 
46 
8 

17i 
160 
82 
126 
113 
111 
116 
117 
138 
136 
160 

53, <;<! 
5:5 

53 

56 

62 

63 

63 

65 

60 

30 

164 

165 

6, 164 

164 

164 

164 

168 

19 

119 

207 

68 

200 

182 



IKDEX 227 



Page 

Quince, Fungi affecting, .... 47 

black rot, . . . . .50 

fruit spot, .... 47 

leaf-blight, ... .47 

rust, . 49 

twig-blight, . . . . .61 

Raspberry, Fungi affecting, .... 97 

anthracnose, . . . . .07 

orange rust, .... 101 

Roextelia, . . . . .36 

" aurantiaca, .... 49 

Rose, Fungi affecting, . . . . .114 

mildew, .... 114 

phragmidium, . . . . .117 

rust, .... 115 

Saprophytes, ..... 5 

Saprophytic fungi, .... 5 

Seploria cerasina, . . . . .64 

diqnthi, .... 121 

" petroselini, . . . . .146 

" ribis, ... 91 

Shade trees, Fungi affecting, .... Ill 

catalpa leaf-spot, . . . . Ill 

cottonwood leaf -rust, . . . .111 

maple leaf-spot, . . . . 113 

sycamore blight, . . . . .113 

Soda hyposulphite, . . . . 19 

Sorghum, Fungi affecting, .... 214 

blight, .... 214 

grain smut, . . . . .216 

head smut, .... 216 

Sphaceloma ampelinum, . . . . .87 

Sphcerella fragarice, . . . . 104 

Sphceropsis malorum, . . . . .50 

Sphcerotheca mors-uvce, .... 93 

" pannosa, . . . . .114 

Spinach, Fungi affecting, . . . 176 

anthracnose, ..... 177 

mildew, .... 176 

Spraying pumps, ... .22 

bushes, .... 23 

Strawberry, Fungi affecting, . . . .104 

leaf-blight, . . . 2,104 

Sulphate of copper, ... .19 

Sulphur, . . 20 



228 



AND l-T\<;iriI>KS 



Sycamore blight, 

Sweet potato, Fungi affecting, 

l>l;trk rot, 
Swarm spores, 

1/rfornnina, 



Ti/lrttti /in It //s, 

Tomato, Fungi affecting, 

bacterial blight, 

rot, 

winter blight, 
Uncinufd ampelopiridix, 

Ul'fH'UXti* Cl'/lll/ll', 

I r mm i/<-t x IK Id, 



" trifolity 
I 'xf if <i(/n (iff /id\ 

" reiliana, 

" sort/hi, 

" trifici, 

" zece-mays, 
Verbena mildew, 
Vermicularia 
Water, 
Wheat, Fungi affecting, 

bunt, 

loose smut, 

rust, 

seal), 

stinking smut, 

Weather, relation to diseases, 
Winter spores, 



Page 

L18 

17-J 

17- 

8 

87 

60 

1!H 
17!) 
180 
17!' 
180 
88 
l :>_' 
135 

ll'O 

132 

218 

187 
218 
218 

198 
202 

124 

157 

15 

1!)4 
194 

198 

200 

198 

194 

10 

10 



SENT FREE ON APPLICATION. 



DESCRIPTIVE CATALOGUE 



OF 



RURAL BOOKS, 

CONTAINING 110 8vo. PAGES, 

PROFUSELY ILLUSTRATED, AND GIVING FULL DESCRIPTIONS ov 
NEARLY 600 WORKS ON THE FOLLOWING SUBJECTS: 

Farm and Garden, 

Fruits, Flowers, Etc. 

Cattle, Sheep, and Swine, 
Dogs, Horses, Riding, Etc., 

Poultr}', Pigeons, and Bees, 

Angling and Fishing, 
Boating, Canoeing, and Sailing, 

Field Sports and Natural History, 

Hunting, Shooting, Etc., 
Architecture and Building, 

Landscape Gardening, 

Household and Miscellaneous. 



PUBLISHERS AND IMPORTERS : 

ORANGE JUDD COflPANY, 

52 & 54 Lafayette Place, New York. 



Books will be Forwarded, postpaid, on receipt of Price. 



\ N i. iKi/ HOOKS. 

Mushrooms : How to Grow Them. 

Any one who has an ordinary house cellar, woodshed or barn, ean 
grow Mushrooms. Tliis is I he most praet ical work on the subject 
ever written, ami tin- only book on growing .Mushrooms published 
in America. The author describes how In- grows .Mushrooms, and 
how they are grown I'"' profit by the leading market gardeners, ami 
for home use by the most successful private growers. Engravings 
drawn from nature expressly for this work. 15y Win. Falconer. 
Cloth. Price, postpaid . 1.50 

Land Draining:. 

A Handbook for Fanners on the Principles and Practice of Drain- 
ing, by Manly Miles, giving the results of his extended experit-m-e 
in laying tile drains. The directions for the laying out and the 
construction of tile drains will enable the farmer to avoid the 
errors of imperfect construction, and the disappointment that 
must necessarily follow. This manual for practical farmers will 
also be found convenient for references in regard to many ques- 
tions that may arise in crop growing, aside from the special sub- 
jects of drainage of which it treats. Cloth, 12mo. 1.00 

Allen's New American Farm Book. 

The very best work on the subject; comprising all that can be con- 
densed into an available volume. Originally by Richard L. Allen. 
Revised and greatly enlarged by Lewis F. Allen. Cloth, 12mo. 2.50 

Henderson's Gardening for Profit. 

By Peter Henderson. The standard work on Market and Family 
Gardening. The successful experience of the author for more than 
thirty years, and his willingness to tell, as he does in this work, the 
secret of his success for the benefit of others, enables him to give 
most valuable information. The book is profusely illustrated. 
Cloth, 12mo. 2.00 

Henderson's Gardening: for Pleasure. 

A guide to the amateur in the fruit, vegetable and flower garden, 
with full descriptions for the greenhouse, conservatory and window 
garden. It meets the wants of all classes in country, city and vil- 
lage wno keep a garden for their own enjoyment rather than for 
the sale of products. By Peter Henderson. Finely Illustrated. 
Cloth, 12mo. 2.00 

Johnson's How Crops Grow. 

New Edition. A Treatise on the Chemical Composition, Structure 
and Life of the Plant. Revised Edition. This book is a guide to 
the knowledge of agricultural plants, their composition, their 
structure and modes of development and growth ; of the complex 
organizations of plants, and the use of the parts; the germination 
of seeds, and the food of plants obtained both from the air and 
the soil. The book is a valuable one to all real students of agricul- 
ture. With numerous illustrations and tables of analysis.- By Prof. 
Samuel W. Johnson of Yale College. Cloth, 12mo. 2.00 



STANDARD BOOKS. 

Johnson's How Crops Feed. 

A Treatise on the Atmosphere and the Soil, as related in the 
Nutrition of Agricultural Plants. This volume the companion and 
complement to "How Crops Grow" has been welcomed by those 
who appreciate the scientific aspects of agriculture. Illustrated. 
By Prof. Samuel W. Johnson. Cloth, 12mo. 2.00 

Market Gardening and Farm Notes. 

By Barnet Landreth. Experiences and Observations for both 
North and South, of interest to the Amateur Gardener, Trucker and 
Farmer. A novel feature of the book is the calendar of farm and 
garden operations for each month of the year; the chapters on 
fertilizers, transplanting, succession and rotation of crops, the 
packing, shipping and marketing of vegetables, will be especially 
useful to market gardeners. Cloth, 12mo. 1.00 

Forest Planting:. 

A Treatise on the Care of Woodlands and the Restoration of the 
Denuded Timber-Lands on Plains and Mountains. By H. Nicholas 
Jarchow, LL. D. The author has fully described those European 
methods which have proved to be most useful in maintaining the 
superb forests of the old world. This experience has been adapted 
to the different climates and trees of America, full instructions be- 
ing given for forest planting on our various kinds of soil and sub- 
soil, whether on mountain or valley. Illustrated, 12mo. 1.50 

Harris* Talks on Manures. 

By Joseph Harris, M. S., author of "Walks and Talks on the Farm," 
"Harris on the Pig," etc. Revised and enlarged by the author. A 
series of familiar and practical talks between the author and the 
Deacon, the Doctor, and other neighbors, on the whole subject of 
manures and fertilizers: including a chapter especially written for 
it, by Sir John Berniet Lawes of Rothamsted, England. Cloth, 
12ino. 1.75 

Truck Farming: at the South. 

A work which gives the experience of a successful grower of vege- 
tables or " truck" for Northern markets. Essential to any one who 
contemplates entering this promising field of Agriculture. By A. 
Oemler of Georgia. Illustrated, cloth, 12mo. 1.50 

Sweet Potato Culture. 

Giving full instructions from starting the plants to harvesting- and 
storing the crop. With a chapter on the Chinese Yam. By James 
Fitz, Keswich, Va., author of "Southern Apple and Peach Culture." 
Cloth, 12mo. .60 

Heinrich's Window Flower Garden. 

The author is a practical florist, and this enterprising volume em- 
bodies his personal experiences in Window Gardening during a 
long period. New and enlarged edition. By Julius J. Heinrich. 
Fully illustrated, Cloth, 12mo. .75 



STANDARD BOOKS. 

Greenhouse Construction. 

By Trot. L. R.T.ilt. A complete treat ise on 'Ireonhouse structures 
and arrangements of I lie various forms :nnl st \ h-s ( >l I'lant Houses 
for professional tlorists us well as amateurs. All the lies I and most 
approved structures are so fully and clearly deserved that anyone 
who desires to build a ( ireeii house will have no difficult y in deter- 
mining the kind best suited to his purpose. The modern and most 
successful methods ot heat ing and ventilating are fully treated 
upon. Special chapters are devoted to houses used for tin-growing 
Of one kind of plants exclusively. The construction of hotbeds 
and frames receives appropriate at tent ion. Over one hnndre- 1 
cllent illustrations, specially engraved lor this work, make every 
point clear to the reader and add considerably to the artistic ap- 
pearance of the book. Cloth, 12tno. 1.50 

Bulbs and Tuberous-Rooted Plants. 

By C.L.Allen. A complete treatise on the History, Description, 
Methods of Propagation and full Directions for the successful cul- 
ture of Bulbs in the garden, Dwelling and Greenhouse. 
ally treated, bulbs are an expensive luxury, while, when properly 
managed, they afford the greatest amount of pleasure at the least 
cost. The author of this book has for many years made bulb grow- 
ing a specialty, and is a recognized authority on their cultivation 
and management. The illustrations which embellish this work 
have been drawn from nature, and have been engraved especially 
for this book. The cultural directions are plainly stated, pract ical 
and to the point. Cloth, 12mo. 2.00 

Henderson's Practical Floriculture. 

By Peter Henderson. A guide to the successful propagation and 
cultivation of florists' plants. The work is not one for florists and 
gardeners only, but the amateur's wants are constantly kept in 
mind, and we have a very complete treatise on the cultivation of 
flowers under glass, or in the open air, suited to those who grow 
flowers for pleasure as well as those who make them a matter of 
trade. Beautifully illustrated. New and enlarged edition. Cloth, 
12mo. 1.50 

Long's Ornamental Gardening for Americans. 

A Treatise on Beautifying Homes, Rural Districts and Cemeteries. 
A plain and practical work at a moderate price, with numerous 
illustrations and instructions so plain that they may be readily 
followed. By Elias A. Long, Landscape Architect. Illustrated, 
Cloth, 12mo. 2.00 

The Propagation of Plants. 

By Andrew S- Fuller. Illustrated with numerous engravings. An 
eminently practical and useful work. Describing the process of 
hybridizing and crossing species and varieties, and also the many 
different modes by which cultivated plants may be propagated and 
multiplied., Cloth, 12ino. 1.50 




University of Toronto 
Library 



DO NOT 

REMOVE 

THE 

CARD 

FROM 

THIS 

POCKET 




Acme Library Card Pocket 

U^der Pat. "Ref. Index File" 

Made by LIBRARY BUREAU