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FUNGOID DISEASES

OF

FARM AND GARDEN CROPS

FUNGOID DISEASES

OF

FARM AND GARDEN CROPS

BY

THOMAS MILBURN, Ph.D., N.D.A., N.D.D.

/ -» /

SECRETARY OF AGRICULTfRK, LANCASHIRE COLNTV COUNCM., AND EECTUREK IN AfJRICLI.TLKE,

LANCASHIRE COUNTY COUNCIL AGRICULTURAL SCHOOL, HARRIS INSTITUTE,

PRESTON; LATE LECTURER ON PLANT DISEASES AT THE

MIDLAND AGRICULTURAL COLLEGE,

KINGSTON, DERBY

WITH A PREFATORY NOTE BY

E. A. BESSEY, M.A., Ph.D.

PROFESSOR OF BOTANY, MICHIGAN AGRICULTURAL COLLEGE, EAST LANSING ; LATE PATHOLOGIST

IN CHARGE OF UNITED STATES DEPARTMENT OF AGRICULTURE'S SUBTROPICAL

LABORATORY FOR PLANT DISEASES AT MIAMI, FLORIDA; FORMERLY

PATHOLOGIST IN THE BUREAU OF PLANT INDUSTRY,

UNITED STATES DEPARTMENT OF ACJRICULTURE,

WASHINGTON

WITH DIAGRAMS

LONGMANS, GREEN AND CO.
39 PATERNOSTER ROW, LONDON

FOURTH AVENUE & 30tii STREET, NEW YORK
BOMBAY, CALCUTTA, AND MADRAS

I915

S3 7 33

PREFATORY NOTE.

By E. a. BESSEY, M.A., Ph.D.

That crops are subject to diseases of various
kinds, has been known for thousands of years.
In the Bible we find reference to mildews and
blasted crops, while among the Roman writers
a number of different diseases were recognized.
As early as the middle of the eighteenth century,
considerable study had been made of some of
the fungi which caused plant diseases, but even as
late as the third and fourth decade of the nine-
teenth century, there were some scientific agri-
culturists who insisted that the spots and dis-
colorations caused by fungi, or the spore masses of
these fungi, were but parts of the plant itself, while
even to the present day, some persons regard such;
epidemics as punishment or warnings sent by the:
Almighty to a sinful people. The brilliant re-
searches, however, of the great British and Ger-
man mycologists of the middle of the nineteenth

V

vi PREFATORY NOTE

century for ever dispelled these views among en-
lightened scientists and gave the first impetus
toward the study of plant diseases from a rational
standpoint. We now know that aside from the
injuries caused by insects or other animals, nearly
every cultivated plant is subject to attack by
few or many parasitic fungi or bacteria. In
addition to these diseases and to those caused by
unfavourable climatic or soil conditions, there are
also some diseases, well marked in their character
and so far as we can determine, absolutely non-
parasitic in origin, the cause of which appears to
be spontaneous to the plant. Such diseases offer
a fine field for investigation by the thoroughly
trained student.

As the causes of plant diseases became known,
attempts were made to develop rational methods
of combating them. Thus the mycologists were
succeeded by the plant pathologists who attempted
to determine not only the cause of each disease,
but the conditions favourable and unfavourable
to its development. In the case of diseases caused
by parasitic organisms, it became necessary to
follow out in detail every step of the life history
of these organisms in their relation to their hosts,

PREFATORY NOTE vii

so that their methods of entry and their vuhier-
able periods could become known. The develop-
ment of fungicides, especially Bordeaux mixture,
was a natural result of the realization that fungi
are the causes of most plant diseases. The newest
researches now attempt to correlate what Is known
of the life history of the parasite and of its manner
of entering the host with the facts learned as to
the relation of the weather to Infection, and to
plan the application of fungicides accordingly.
Another line of research Is the development of
the resistant types of crops, but this is for the
plant breeder, primarily.

In the present book, the author attempts to
present. In a form capable of being understood
both by students and by agriculturists, a brief
discussion of each of the more important diseases
of the common field and garden crops. Of
necessity such a book cannot be complete as to
all diseases known on all crops. Indeed, such a
work would be undesirable and so bulky as to
be almost useless. The author has approached
the subject with a practical understanding of what
is wanted in such a book by the agriculturist
who frequently lacks the technical knowledge to

viii PREFATORY NOTE

understand some of the more pretentious tech-
nical works on the subject. On the other hand^
he has not sacrificed scientific accuracy in his
attempt to make the book one that can be under-
stood. It is, then, a book to become acquainted
with which wull well repay the student who wishes
to learn something of the commoner diseases of
these crops.

The writer of this preface has had the pleasure
of reading the whole manuscript and of making
suggestions and comments, many of which have
commended themselves to the author and have
been adopted by him. If these suggestions and
additions may serve to make this book more
valuable, the writer of this preface feels that he
has been amply rewarded.

E. A. BESSEY.

Michigan Agricultural College,

East Lansing,

Michigan, U.S.A.

AUTHOR'S PREFACE.

This Introduction to the study of Plant Diseases
has been compiled primarily for the use of Farmers,
Gardeners, and Agricultural Students, but it is
hoped that it may have a wider field of infiuence,
and that those engaged in teaching and County
lecturing may find in Its pages material of interest
and of value.

I have aimed at simplicity In definition and
have not attempted too much detail of a purely
scientific nature. I am aware of its Incomplete-
ness, but Its size precludes the Inclusion of the
more minor diseases and of fuller details In the
case of those diseases treated. I hope, however,
that any deficiency In detail will be compensated
for by the points of special merit, and that It may
be found worthy of a place on every agriculturist's
bookshelf.

Many of the drawings are original, and where
otherwise are duly acknowledged.

X AUTHOR'S PREFACE

I desire to acknowledge my indebtedness to
my good friend E. A. Bessey, M.A., Ph.D.,
Professor of Botany, Michigan Agricultural Col-
lege, for kindly writing the Prefatory note and
the subject matter on pages 29, 30, 33-38, 79 and
83 ; for reading the whole of the proofs and for
many other valuable suggestions and additions.

To any others who have assisted me either
directly or indirectly I tender my best thanks.

THOMAS MILBURN.

(Bounty Offices,
Preston, July^ 1915-

CONTENTS.

PAGES

Prefatory Note v-viii

Author's Preface ix-x

CHAPTER I.
General Information 1-38

CHAPTER II.
Fungoid Diseases of Cereals 39-62

CHAPTER III.

Fungoid Diseases of Leguminous Plants (Peas,

Beans, etc.) 63-74

CHAPTER IV.
Fungoid Diseases of Potatoes . . . • 75-93

CHAPTER V.
Fungoid Diseases of Crucifers (Turnips, Cahrage,

ETC.) 94-102

CHAPTER VI.
Fungoid Diseases of Mancjels and Beet . . 103-108

APPENDIX.
Fungoid Diseases of Farm Animals . . . 109-113

Index 115-118

FUNGOID DISEASES OF FARM AND

GARDEN CROPS.

CHAPTER I.

GENERAL INFORMATION.

The diseases described in the subsequent pages of
this book are caused by fungi (low forms of vege-
table life) which rob the larger plants of part of their
nourishment. The term fungi, however, is some-
what vague, hence it will be well at the outset to
state definitely in what light the word will be used.
In its wider sense it embraces not only the h'tce fungi,
but also the bacteria, while in the narrower light it
includes the true fungi only — bacteria coming in a
separate class. Practically all the diseases described
herein are caused by the true fungi, and hence the
term is used throughout in its narrower sense. ^
Everyday examples of true fungi are to be found
in the various moulds on fruit, jam, cheese, and in
the mushrooms, toadstools, mildews, etc.

A classification of fungi is given on p. 34, where

1 A few diseases not caused by true fungi will be described, but
these will be noted in the text.

I

2 FUNGOID DISEASES

it will be seen that they form a number of classes
which have probably arisen by the degeneration (it
may be said through the loss of chlorophyll) of
forms in various groups of green, or at least chloro-
phyll-containing, low water-plants called algce.
Owing to their being devoid of chlorophyll, they
are entirely dependent for their food on matter al-
ready built up, either by higher plants, or by ani-
mals. Those deriving their nourishment from
living organic matter are called parasites, others
deriving it from dead matter are called saprophytes
(see p. 1 2).

Before passing on to the actual plant diseases, a
few botanical terms must be described and a little
general information given in order to make the
context of the book more easily understood.

HyphcB. — Most fungi have their vegetative part
(the body of the fungus, or that part which takes
up food) in the form of very fine delicate threads
called hyphae (Fig. i), which are mostly invis-
ible, singly, to the naked eye. They are in reality,
fine transparent tubes containing a semi-fiuid sub-
stance called protoplasm, which is the vital part. It
circulates slowly inside these tubes, and in it are em-
bedded numerous nuclei, fat globules, etc. Growth
of the hyphae takes place at the tip.

Mycelium. — Usually the hyphae do not remain
long as single threads, but branch and re-branch,
becoming thereby interlaced and forming what is

GENERAL INFORMATION 3

termed the mycelium (Fig. i). This mycelium
then is nothing more than a network of hyphae
which, when a fungus has grown some time, is
visible to the naked eye, as seen in the grey covering
called mildew on turnips and other plants, and in
the white or ereen mould on bread and cheese.

A

B

Fig. I.— (A) Conidiophore oi Penicillium glancum {c 2) highly magnified ;
(5. s.) sterigmata or spore-bearing branches ; [c i) conidia or spores ;
(B) portion of mycelium of PoticilHiun which has developed from the
spore (s) ; b.b.b. branches or hyphae ; notice the brush-like groups
of conidia. (After Brefeld.)

The words hyphee and mycelium often form a
stumbling-block to students, and consequently the
following illustration is given with a view to making
them clearer. If we take a single thread drawn from

T *

FUNGOID DISEASES

a piece of cotton-wool to represent a hypha, then
several such threads represent the hyphae ; and a
little of the wool spread out thinly corresponds to
the mycelium.

Sporangiophore and Conidiophore. — After ''feed-
ing" for a time, certain aerial hyphas grow out from
the mycelium, on which spores are subsequently

A B

Fig. 2. — Mucor mucedo — (A) Showing the formation of a sporangium ;
(B) the sporangium full grown containing the oval spores. The stalk
(5) is called a sporangiophore. (Highly magnified.)

formed. If the spores are enclosed in a sac (e.g.
Mucor mucedo, Fig. 2) these aerial hyphas are called
sporangiophores, if they are borne externally on
branches the aerial hyphse are called conidiophores.
Sclet'otia. — Under certain conditions — usually
when food or moisture is lacking — the hyphae, at
certain points of the mycelium, branch and interlace
to such an extent that firm felted masses called
sclerotia result. These sclerotia are hard and

GENERAL INFORMATION

5

usually dark coloured ; and the hyphce forming them
are rich in food substances. They constitute a
resting stage, in that they can withstand cold,
drought, etc. ; and after a longer or shorter period
of rest, are capable of starting growth (see p. 55,
under ergot). When sections of sclerotia are ex-
amined under the microscope they resemble, to
some extent, the tissue of the higher plants.

A

E3

Fig. 3. — (A) Sclerotiuin of Clavueps pnrpui'ea (Ergot) ; (B) Sclerotium
of Sclerutinia trifoliornm ; (C) Is a section through a sclerotiuin
showing cell-like appearance, somewhat diagrammatic and highly
magnified.

HaiLstorla (Suckers). — Parasitic fungi which live
on the surface of the host plant (e.g. Erysiphc), and
many of those living in the intercellular spaces (e.g.
Piiccinia graininis), are provided with special organs,
for the absorption of food, called haustoria, or
suckers.

These haustoria are modified portions of the
hyphae, and are of no fixed form (Fig. 4). In the
Erysiphacece they consist of foot-like expansions

6 FUNGOID DISEASES

firmly attached to the leaf surface, which send a very
fine thread into the inside of the cells of the host.
This fine thread forms a sack-like swelling inside,
which gives a larger surface for the absorption of
food. There is, however, greater variety of form in
the haustoria of those fungi which live inside the
plant (endophytic). Saprophytic fungi, and those
parasitic fungi which live inside the cells of the

Fig. 4. — Showing the formation of a haustoriuni or sucker ; (B) in a
species of Erysiphe ; (A) the hyph^e ; (C) the surface cells of the leaf.
(Somewhat diagrammatic.)

host, are not so dependent on these special organs
for the absorption of food, as in their case it can
be taken in over the entire surface of the hyphse.

Spores. — These are extremely minute portions
of protoplasm which become separated from the
parent fungus for the purpose of reproducing its
kind, serving the same function for the fungus that
seeds do for the higher plants. They are usually
— though not always^surrounded by a protective

GENERAL INFORMATION 7

covering — the wall of the spore. There are a
variety of types, but for convenience we may class
them under two heads : —

(a) Those which are formed as a result of some
sexual union, e.g. oospores, zygospores, etc.

(d) Those formed asexually, i.e. not — so far as is
known — by any sexual act, e.g. conidia, endospores,
chlamydospores.

Under each of these heads the shape of the
spores is very varied. They may be : —

Round as in Penicillmm glauciun,

Oval as in Mucor mitcedo,

Angular as in Oidium lactis,

Crescent shaped as in Pusarhwi solaniy

Needle shaped as in Claviceps ptcrpitrea (asco-
spores).

Kidney shaped as in many Basidiomycetes ;
indeed, diversity in shape may be noticed in spores
growing side by side on the same branch. Irre-
spective of the shape, most fungus spores are easily
carried in the atmosphere from place to place ;
where they may either be capable of immediate
germination, or they may remain dormant for a
considerable time prior to growth. In either case
a new centre of infection is set up by each individ-
ual spore thus carried.

Germination of Spores. — The germination of
spores, and the growth of a fungus generally, are
best studied by making what are called drop cul-

8

FUNGOID DISEASES

tures, and observing the changes from time to time
under the microscope. They may be made as
follows : —

Upon a piece of ordinary glass 3|- in. x i in.
(Fig. 5, A) place a small piece of cardboard ^ (B)

'SMi'lFl^i^'^^':^!^

Fig. 5. — Sketch showing how drop cultures are made, on which the ger-
mination of spores and growth of fungi may be observed direct under
the microscope. Also shown in section. Description in text.

about one inch square, having a hole (C) in the
centre. Take a very thin piece of glass one inch
in diameter (cover glass) clean and sterile, and
place upon it, by means of a glass rod, a drop of
sterile water or other substance.^

Place the smallest possible number of spores on

^ Boil the cardboard for one minute prior to using, and keep all
glass and instruments used as sterile as possible.

^ Various substances are used, e.g. prune juice, dung extract,
sugar solutions, beer wort, etc. ; some spores germinating best in
one, some in another. All substances used must be germ free.

GENERAL INFORMATION g

the drop by means of a very fine platinum needle,
then invert and place over the cardboard (B). The
drop of nutriment which has been inoculated with
the desired spores now hangs from the cover glass
in the chamber (C) formed by the slide below, the
hole in the cardboard, and the cover glass above.
Without disturbing this in any way the growth of
the spores may be studied by frequent examination
under the microscope/

The change which spores undergo when placed
upon such a drop depends upon the composition of
the liquid forming the drop, and in part to the sur-
rounding conditions. The spores of many parasitic
fungi refuse to germinate in almost any solution ;
others will germinate in one solution but not in
another, e.g. spores of Tilletia (bunt) germinate
freely in water but refuse to grow when placed in
drops of food solutions. Then again some spores
give different changes in different liquids, e.g.
spores of Ustilago (smut) germinate in water and
very dilute food solutions ; but in solutions contain-
ing abundant nutriment they multiply by a process
called budding.

The typical germination of a spore consists in the
protrusion of a portion of the wall which gradually
develops into a delicate tube (Fig. 6, B) ; this

^ It is advisable to keep at a medium temperature, and place in-
side moist chambers, as this keeps the drop of nutriment from dry-
ing up.

10 FUNGOID DISEASES

branches and re-branches, ultimately forming the
mycelium which is capable of unlimited growth under
favourable conditions. Many spores are capable of
germination after passing through the body of an
animal ; the wall of the spores having resisted the
effect of the digestive juices. This is a point of
great importance, and one that should never be lost
sight of in combating the attack of any particular
fungoid disease.

Q (J

Q

Q>

A

\>ic_ 6. — Showing germination of the spores oi PcniciUium glancitiii : (A)
the spores before germination ; (B), (C) successive stages in germina-
tion ; {tj the germ tube. In (C) cross walls have been formed in the
hyphae {h). (Highly magnified.)

Reproduction. — We have just seen that quite a
variety of spores are formed, by the different fungi,
for the purpose of reproduction, some forming one
kind, somie another ; but what is even more inter-
esting is the fact that the same fungus may form
more than one kind. Many examples might be
given, but perhaps one of the most striking amongst
parasitic fungi is Piiccinia grauiinis (rust), which

GENERAL INFORMATION ii

forms on wheat uredospores and teleutospores ;
while the same fungus when growing on the bar-
bery [Berderis vulgaris) produces aecidiospores and
picnospores.

On making a study of saprophytic fungi, it is
found that the particular form of spore produced
depends upon the conditions of food, temperature,
air supply, moisture, etc. ; provided these remain
constant, so does the form of the spore ; but change
any or all of the factors, and a change in the spore
formation usually results. Moving the mycelium
of some fungi from a rich nutritive medium into a
poorer one, or into distilled water, will immediately
result in a chancre of fructification. In a similar
manner lack of water, or lack of food, will cause
change. It will be seen then that diversity in the
type of reproduction serves a most useful purpose
to the funo^us in case of emergfencies ; in that al-
though the conditions may be unfavourable to
growth, and the mycelium may die in consequence,
the spores remain to perpetuate the species, when
and if more favourable conditions are afforded.
In combating any disease this should be carefully
borne in mind.

Just as gooseberry bushes may be increased in
number by putting detached portions under favour-
able conditions for growth, so also can small por-
tions of mycelium serve to increase the amount of
fungus growth. This method of increase, however.

12 FUNGOID DISEASES

sinks into insignificance under the profuse produc-
tion of spores.

Pa^^asites^ and Saprophytes. — According to the
source of food, we divided fungi into parasites and
saprophytes (see page 2). This division, how-
ever, is somewhat arbitrary, for many parasitic
fungi are capable of living wholly or partly as
saprophytes. In like manner, some saprophytes
are able to exist as parasites. A better division is
as follows : —

1. Totally Parasitic. — Fungi whose whole life is
spent on living matter, and which, so far as our
present methods of cultivation allow, will not grow
on dead organic substances, e.g. the Ui^edinales
(rusts) and the different species of Eiysiphacece
(mildews).

2. Semi-parasitic, — Fungi which are capable of
growth for all, or part, of their life cycle as sapro-
phytes, but which are typically found parasitic for
part, or all, of this cycle. The smuts are capable
of growth indefinitely as saprophytes, but do not
produce the typical smut spores unless they grow
as parasites ; on the other hand all stages of the
potato fungus [Pkytopht/iora) can be grown sapro-
phytically, although in nature it is commonly found
only as a parasite.

1 A parasite may be looked upon as a robber of the plant, and
stands in much the same relation to the host as a lazy fellow does
to his victim, from whom he obtains food and money.

GENERAL INFORMATION 13

3. Totally Saprophytic. — Fungi which are un-
able to exist as parasites, and which in consequence
do not cause disease to either plants or animals.
They merely play the part of scavengers, hastening
the decay of refuse matter.

4. Hemi- saprophytic. — Fungi which live chiefly
as saprophytes, but which are able to exist either
partly or totally as parasites, e.g. various species of
Mzccor and Penicillium ; or even more so the dif-
ferent species of Polyporus — seen as sponge-like
masses on trees — which, as parasites, are able to
kill living cells, but are also capable of living totally
saprophytic.

Each of these four heads might be sub-divided,
but for this work it will suffice to divide the purely
parasitic fungi into : —

(a) Epiphytic — parasites which live on the surface
of the host, e.g. species of EjysiphacecE (mildews).

(^) Endophytic — parasites which live inside the
plants ; either in the intercellular spaces (the space
between the cells) or inside the cells, e.g. Phyto-
phthora infestans inside the cells of the diseased
potato.

Effect of Parasite on the Plant. — The changes
brought about by parasitic fungi are exceedingly
varied ; the plant may succumb to the attack of the
fungus in a few days, e.g. as seen in the "damping
off " of cress, or the host and parasite may live to-
gether for a long time without disastrous results,

14 FUNGOID DISEASES

as seen in the brain-like swellings on such trees as
the elm. In some cases the invaded tissues are killed,
in others only certain tissues or only certain areas,
while often the fungus simply robs the affected
tissues of certain food stuffs so that death does not
occur ; indeed the tissue may be stimulated to ab-
normally active growth.

The injury due to the presence of the fungus
itself may be very slight but its consequences far-
reaching. The destruction of leaf tissues by many
fungi leads to starvation of the whole plant owing
to the destruction of the food manufacturing organs
(leaf tissues) ; so also a fungus may simply destroy
the root hairs (the fine feeding roots), the death of
the plant resulting from the destruction of these
water-absorbing organs. The rust of wheat {Pitc-
cinia grauiinis) is chiefly injurious in that it splits
the stems and so permits them to dry out. In
many cases the fungus secretes poisons which pass to
various parts of the plant causing various reactions.

Some of the results of parasitic attack are men-
tioned below : —

1. Sudden collapse of the host as above-
mentioned.

2. Plant and parasite may live together for years,
with comparatively slight alteration of tissue, e.g.
species of Exoasctts on trees.

- 3. Abnormal fruit, e.g. Exoascus pntni, causing
the disease known as ''pocket plums".

GENERAL INFORMATION 15

4. Abnormal llowering — ^where the attacked part
flowers at a different time from the rest of the plant,
e.g. "witches' broom" on the cherry tree.

5. Suppression of part of the reproductive organs,
e.g. Ustilago (smut) on Lychnis dioica (campion).

6. Premature development of buds, e.g. a
diseased potato usually develops the buds earlier
than the healthy ones, and the same phenomenon
is seen in the ''witches' broom" on the elder.

7. Contortions of the most varied nature, e.g.
Cystoptts candidus on Capsella Inu'sa pastoris (shep-
herd's purse).

8. Discoloration of the parts affected — most
fungi.

9. Formation of different colours, e.g. Rki.zoctoma,
violet on roots, and Fitsarium (species), rose-pink
on potatoes.

10. Cell wall and cell contents changed by means
of ferments, e.g. wall and starch grains in a diseased
potato.

Others might be given, but these will suffice to
convey to the mind of the reader the great changers
which are brought about.

Influence of Host on Parasite. — While parasites
are able to bring about such contortions, etc., in
plants, these in turn are not without their effect on
the attacking party. Certain fungi are only capable
of existing on plants of a particular genus ; others
again on a single species, while some can only

i6 FUNGOID DISEASES

make " healthy " growth on certain varieties of the
same species. The different varieties of wheat,
barley, potatoes, etc., show marked differences in
the power of warding off the attacks of their re-
spective diseases ; e.g. while one variety of potato ^
forms a suitable feeding ground for Phytophthora,
and falls a prey to disease in consequence ; another
is unfavourable to its development and as a result
suffers less from the attack. This diversity is due
in a great measure to the difference in the relative
amounts of the various chemical substances within
the plant. Influence of plant on parasite is again
shown where a change of the host results in the
formation of a different kind of spore, as is well
instanced in Pticcinia graminis which forms on
wheat uredo- and teleuto-spores, while on the bar-
bery {^Berberis) aecidiospores are produced ; again
Cystopus candidus (producing white rust in cruci-
fers) on shepherd's purse forms only conidia, while
on some other plants belonging to the same order
another kind of spore is formed, viz. oospore.

The above examples show that the host exerts
a very considerable influence on the parasite.

Signs of Disease. — The various changes enum-
erated under ''Effect of Parasite on Plant" (p.
13) indicate the presence of some attack. These

^ Grown under identical conditions, some varieties may have over
two tons of diseased tubers to the acre, e.g. " Up-to-Date," and others
not as many cwts., e.g. " King Edward VII ".

GENERAL INFORMATION 17

abnormal conditions may be classed under three
heads, viz. : —

1. Discoloration,

2. Abnormal outgrowths,

3. Death,

the two latter of which may, or may not, be pre-
ceded by the former. Change in colour, however,
may be said to be one of the most frequent results
of disease attack ; such change may be reduction
ot the natural colour generally, or, what is of more
frequent occurrence, the local formation of new
colour.

We see then how important It is that the farmer
should train his eye — already quick at observing
most things — to detect any change In colour in
part, or the whole, of his crop ; for if disease be
present, it may still be possible, by applying stimu-
lating manures to the soil, or fungicides to the leaf,
to mitigate the extent of the attack ; growth of the
plants being assisted by the former, and healthy
plants protected by the latter.

Diagnosis of Disease. — Abnormalities of any
kind having been noticed In a few or many plants,
it is essential that some idea should be formed as
to the cause. If preventive measures are to be
adopted to limit the extent of the attack, and here
comes the farmer's difficulty. A small pocket
magnifying glass will often reveal much that is
obscure to the naked eye — no student of agri-

1 8 FUNGOID DISEASES

culture or farmer should be without one — but for a
more critical examination a microscope is necessary.
Spread of Disease. — The spread of disease may
be brought about in a variety of ways, the chief of
which are enumerated below : —

1. Movement of disease spores in the atmosphere
by wind.

2. Spores or diseased parts of plant carried by
animals, man, implements, etc.

3. Transportation of infected soil by animals,
implements, etc.

4. Growth of fungus from centre of infection.
The spores which constitute the chief form of

reproduction in parasitic fungi are exceedingly
minute, and when detached from the fungus threads
most of them are easily carried by the wind from
place to place, thus spreading the disease. This is
well instanced in the spores of the fungus causing
potato disease {^Phytophthord) which are carried from
field to field ; and accounts for the rapidity of its in-
crease, and extent of its devastation, under favour-
able conditions (see later). These same spores, and
those of other fungi not carried by wind, may be-
come attached to the feet or bodies of insects, birds,
rabbits, man, implements, etc., and thus disseminate
the disease. Diseased plants when carted from the
root shed and thrown on previously uninfected
areas cause direct contamination, as also does the
manure from cattle which have eaten diseased

GENERAL INFORMATION 19

plants or seeds, for many spores are not attacked
by the digestive juices of the stomach and are thus
capable of germination under favourable conditions.
Birds carry diseased fruits from place to place.
Soil from an infected area may be carried by im-
plements, etc., to different parts of the same, or
other fields, e.g. spread of *'finger-and-toe " disease.
Diseases spread in this manner, i.e. carried by
animals, etc., although by no means easy to check,
can be more successfully prevented than those
whose spores are carried by the wind.

How Fungi Gain Admission to the Plant. — It is
not definitely known how many parasitic fungi
gain entrance to the healthy plant, but it may be
in one of three ways : —

1. Digestion of the cell wall.

2. Through the breathing pores.

3. At some wound.

The delicate germ tube which protrudes on
germination is in some cases capable of gaining an
entrance to the plant by digesting the wall with
the ferments which it secretes. The germ tube of
Phytophthora, although usually entering at a breath-
ing pore, is also capable of digesting the cell wall,
while hyphze of Sclerotinia sclerotioruvi are capable
of piercing the cell walls of a variety of plants.
The number of funcri enterino- in this way is, how-
ever, probably over-estimated, for some minute
wound can often be detected.

ry "SK

20 FUNGOID DISEASES

The second mode of entrance Is found In those
fungi whose spores are disseminated by the wind,
e.g. the germ tube from the zoospore of Phytoph-
thora, If near a stoma, enters It, being attracted by
certain food substances — " chemotropism ".

The third method of entrance, I.e. through some
wound, is the most widespread, Indeed It is highly
probable that many fungi which are said to enter In
other ways gain admission in this manner. Many
parasitic fungi may be placed on the surface of a
healthy plant, where the epidermis is intact, without
gaining an entrance ; but should the least abrasion
be made. Inoculation Is almost certain. This Is
well Illustrated in the pruning of large trees ; If no
dressing is applied to the cut surface Polyportts or
some other fungus usually finds an easy entrance
and ultimately causes decay of the parts.

The root hairs of the plant are delicate organs,
and hence it seems fair to conclude that some fungi
enter plants through them. When other channels
of Infection prove uncertain a fungus Is said, either
rightly or wrongly, to pass in via these hairs, but
as before mentioned, some of the cases attributed
to such entrances are more or less obscure, e.g.
Plasmodiophora bras sices.

N'atural Conditions Favouring the Spixad of
Fungoid Diseases. i. Weather Conditions. — A
moist atmosphere combined with warmth provides
the optimum conditions for fungoid development,

GENERAL INFORMATION 21

disease spores being- unable to germinate without
these. Unfortunately the farmer has no direct
control over the weather, but indirectly he can keep
the plants drier by giving them more space. The
effect of moisture is well seen in the case of a field
of potatoes ; the four rows next to the hedge, almost
without exception, suffer more from the Phytoph-
tkoJ'a disease than any other part of the field.
This is so marked that in certain districts the
farmers hold firmly to the opinion that the disease
comes from the trees which constitute the hedo^e.

On the other hand lack of moisture may favour
some diseases, e.g. certain forms of leaf curl in
potatoes. Again, the moisture content of the soil
during the early stages in the growth of swedes may
profoundly influence the extent of finger-and-toe
disease in the subsequent crop, as is shown in the un-
dermentioned case which the author investio-ated : —

Half of a large field sown 8th June, poor crop,
8 1 per cent diseased.

Half of same field sown 15th June, good crop,
1 1 per cent diseased.

The cultivation, manuring, and previous cropping
of the two halves, were the same, but thc^ wc^ather
about the time of the first sowing was dry while
immediately after the second sowing there were
heavy rainfalls on three successive days.

2. Crowded Cropping. — Most plants are mor(i
susceptible to disease when grown closely together :

22 FUNGOID DISEASES

this is due to their not drying so quickly after rain
as when more space is given.

3. Continued Cropping, — -Where plants are grown
continuously on the same land, a suitable host is
always at hand for the disease-producing fungi, and
spread of disease is favoured thereby.

4. Diversity in Host, — Even when crops are not
grown continuously, if w^eeds be allowed to flourish
in the interval, some of these mav act as host until
the same crop is repeated ; for it is known that
some fungi are capable of existing on many, or all,
of the plants of a certain order ; a good example
being found in Plasmodiophora brassicce, which is
capable of living, during the interval between the
turnip crops in the rotation, on cruciferous weeds,
should such be present. This fact is favourable
to the continuance and spread of disease.

5. Badly Nonrished Crops. — Crops which are
ill-nourished usually succumb more readily to disease
than those in a robust condition ; sw^edes grown
where phosphate is deficient suffer more from the
attacks of Plasmodiophora than those having an
adequate supply of this substance. Potatoes ap-
pear to be more susceptible to the attack of certain
forms of leaf curl when low in vitality,

6. Adaptability to Varied Conditions. — The fact
that many plant parasites are able to adapt them-
selves to the most varied conditions favours attacks.
When privations of any kind set in then resting

GENERAL INFORMATION 23

spores are formed, which are capable of withstand-
ing variations of temperature, and subsequently
germinating under favourable conditions. In other
cases sclerotia (see p. 4) are found.

7. T^^ansportation of Spores — Wounds. — Spores
are distributed either by wind or otherwise, and on
germination set up new centres of infection. En-
trance to the plant is made easier by the presence
of wounds, as seen on page 20, and like the other
above-mentioned facts, favours non-extermination.

Natttral Conditions Unfavourable to Spread of
Disease. — From a cursory glance it would appear
as though everything was in favour of the growth
of parasitic fungi ; fortunately such is not the case.
Dry cold weather retards their growth, the cutiniz(xl
(hardened) epidermis of the plant makes entrance
more difficult, and by far the largest bulk of disease
spores find themselves deposited in places unfavour-
able to their development. Furthermore, the ex-
tent to which some varieties of a particular species
of plants are able to resist disease attack, affords
evidence that parasitic fungi meet with natural
factors which limit very considerably the extent of
their ravaofes.

Amount of Damage Done by Fungi. — The loss
which any particular farmer suffers from a fungoid
attack is in itself serious, but it is only when we
take statistics for the whole country that we fully
realize the amount of damage done. Take potatoes

24 FUNGOID DISEASES

as an example, the loss in a " disease year " is
appalling.

According to the returns of the Board of Agri-
culture for the year 191 2, the area under potatoes
in the United Kingdom was 1,219,583 acres, with
an average crop of about 6 tons to the acre. This
gives a total of 7,317,498 tons, which at £2 per ton
are worth ;^ 14, 634, 996 ; but assuming that disease
is rampant, and that one-fourth of the crop is diseased,
if we take the value of the diseased tubers at los.
per ton, the total value of the whole would be
;^i 1,890,934 instead of ^14,634,996, which means
a loss of ^3,744,061 for the United Kingdom
alone.

The losses from ofrain rust for Prussia alone have
been estimated at millions for a single year, while
the loss in Australia due to rust in wheat is put
at 2\ million pounds for one year.

The above figures are only approximate, still
they give us some idea of the extent of the damage,
and impress upon us the importance of adopting
preventive and remedial measures whenever pos-
sible.

Fungicides. — Cultural and other preventive
measures based upon the afore-mentioned favour-
able and unfavourable conditions will be ofiven later
in the text, but it will be well to enumerate here a
few of the common fungicides, and the methods of
preparation,

GENERAT. INFORMATION

25

1. Bordeaux mixture.

2. Soda- Bordeaux.

3. Soda-lime Bordeaux.

4. Copper sulphate solution.

5. Hot water.

6. Potassium sulphide.

7. Formaldehyde.

8. Corrosive sublimate.

9. Lime-sulphur.

10. Flowers of sulphur.

I. Bordeaux Mixture. — This mixture was first
prepared by Millardet in 1885, and has since been
subjected to numerous modifications. Even at the
, present day different strengths are recommended
by various authorities. It is, and is likely to re-
main, the most important fungicide, being popular
on account of : —

1. Its effectiveness as a fungicide.

2. Its cheapness.

3. Its safety from a hygienic standpoint.

4. Its safety to the plant. ^

5. Its beneficial effects other than checking

disease.^
The active principle in the mixture is the copper,
which in very dilute solutions is poisonous to fungi
— some succumb to solutions containing one part of

^ Recent results obtained in Lancashire (L.C.C. Farmers' Bulletin,
No. 27) and elsewhere tend to modify our ideas regardinj^ these
points ; however, further research is necessary.

26 FUNGOID DISEASES

copper per ten million. The exact composition is
unknown, for it varies according to the manner of
preparation, the degree of purity of the lime, and the
copper used. When freshly prepared it consists
essentially of a saturated watery solution of calcium
sulphate and calcium hydroxide, containing in sus-
pension calcium sulphate and copper hydroxide and
a varying amount of calcium hydroxide and calcium
carbonate. When exposed to the air the calcium
hydroxide takes up carbon dioxide, forming calcium
carbonate which is washed away by subsequent
rains . Whether the copper hydroxide undergoes any
change is doubtful, no change is probable until the
whole of the calcium hvdroxide has been neutralized,
when it may become changed to carbonate.^

Preparation. — Strict attention should be paid
to the instructions given below, for on the proper
mixing, and purity of the chemicals used, depends
the value of the resultino- solution as a funo-icide.
No exact formula can be given, as it is always
necessary to test the solution before applying, but
the following will be found about the correct pro-
portions : — ^

1 See "U.S. Dep. of Agr., Division of Vegetable Physiology and
Pathology Bull.," No. 9, 1896, and for more recent work, Pickering,
"Jour, of Agr. Sc," vol. iii. part 2, p. 171, and vol. iv. part 3, p. 273 ;
Gimmingham and Barker, "Jour, of Agr. Sc," vol. iv. part i, pp.
69 and 76 ; vol. 6, part 2, p. 220.

- The amount of copper sulphate is sometimes reduced to equal
the amount of lime.

GENERAT. INFORMATION 2

"/

12 lbs. copper sulphate.
10 lbs. lime (freshly burnt).
100 gallons water.
Three wooden vessels are necessary for the
proper mixino- ; two small and one double their
size — paraffin barrels answer well for small quan-
tities. Powder the copper sulphate, put in a piece of
sacking, and dissolve in half the water in one of the
small vessels. Slake the lime in the other small
vessel with the remainino- water. When the lime
wash is cooled, pour the contents of the two vessels,
after stirrino- both at the same time into the lar^e
receptacle. The resulting solution should be tested
in one of the following ways : for if too much h'me
be present it is useless as a fungicide, if too little, it
is dangerous to the crop.

{a) Ferrocyaiiide Test. — Add one drop of a
solution of potassium ferrocyanide to the
mixture ; if the colour of the drop changes
to a dark, reddish brown, more lime is
necessary, if no change in colour, the mix-
ture is safe to apply.
{[)) Hold a clean knife blade, or other briglit
surface of steel, in the mixture for one
minute, if on removal it is clean, the solu-
tion is safe to use ; if copper is deposited
on the surface of the blade, more lime
must be added.
[c) Litj?ms Paper, — After the liquid has settled

28 FUNGOID DISEASES

a little dip a piece of blue litmus paper

into it ; if the paper remains blue the

mixture is safe to use, if not add more

lime and repeat the test.

After straining- and repeated stirring, apply in

the form of a fine spray in the quantities stated

under the respective diseases — usually from 40 to

80 gallons per acre. For small areas a knapsack

sprayer answers very well, but for larger areas a

horse sprayer should be used.

2 and 3. Soda-Bordeattx and Soda-Lime Bor-
deatix. — The above are modifications of the orio-inal
Bordeaux Mixture ; their preparation is somewhat
critical, and since they possess no effectual advant-
age over the original solution, details as to mixing
will not be oiven.

4. Copper StUphate Solution. — Very dilute solu-
tions of copper sulphate are sometimes used instead
of the Bordeaux Mixture, but since they are more
liable to injure the host plant, and do not stick to
the surface so well, they are not to be recommended
for general adoption. Dilute solutions are, how-
ever, of great value for the treatment of seed grain
for smut and bunt. A common recipe for this
purpose is the following : i lb. copper sulphate and
I gallon of water for each sack of wheat ; the grain
being spread on the floor and the mixture applied
by means of a watering can, while the grain is
being turned. The above mixture is a 10 per cent

GENERAL INFORMATION 29

solution, and is far too strong-, the germination of
the grain being sometimes impaired to a serious
extent.

A better method of prevention is to resort to the
hot water treatment, or to use more dilute solutions
of copper sulphate. Kiihn recommends the follow-
ing : soak the seed in ^ per cent solution of copper
sulphate^ for 12 to 16 hours, remove and dry 24
hours prior to drilling and 4 hours prior to sowing
broadcast. It is an advantage if the grain subse-
quent to the removal from the copper sulphate solu-
tion be put for 3 to 4 minutes in thin milk of lime.^

5. {^^ Jensens Hot Water Treatment. — This has
been successfully adopted in place of the copper
sulphate solutions for the prevention of certain
smuts and bunt.

Three vessels are necessary : —

(i) containing water at 212° F.

(2) containing water at 120° F,

(3) containing water at 133° F.

The grain should be put into wire baskets for
treatment, or open, coarse sacks, which will do
equally well, First immerse for i minute in No.
(2) in order to warm it a little prior to putting into
No. (3) ; now draw out and immerse in No. (3) for
10 minutes, ac/itatinof the mass the whole time.
After the lapse of 10 minutes lift out, dip into cold
water to cool it, and spread on a tloor to dry.

^ The grain may be put in open canvas bags for immersion.

30 FUNGOID DISEASES

Water from No. (i) is used to keep up the bulk
and temperature of Nos. (2) and (3). If properly
carried out the warm water not only kills the spores
of bunt or smut, but also favours subsequent ger-
mination of the ofrain.

Necessary Precautiojis . —

{a) Maintain the temperature of the water in
No. (3) vessel.

(b) Never have it above 130'' F. for barley, the
embryo of which is easily injured by higher tem-
peratures.

{c) Never allow it to rise above 135° F. for other
ofrain.

(d) Have the volume of water at least eight times
as large as that of the sack containing the grain.

[e) Do not fill the sack, but allow free movement
of the grain.

(/) Keep the grain in No. (3) exactly 10 minutes.

iyg) Do not leave in a thick layer after treatment,
but spread out to dry.

With a badly infested sample of wheat the bunted
grains should be removed by throwing the whole in
water — they float on the surface and may be
skimmed off.

(B) Jensens Modified Hot Water Treatment for
Loose Smut of Barley and Wheat. — Soak the
grain in cold water (60° to 70° F.) for 4 or 5
hours ; remove, dip for a moment into a vessel
of water at 120° F., then for barley immerse for

GENERx^L INFORMATION :;i

0

13 minutes in water at 126° F". and for wheat
10 minutes at 129° F., remove to cold water and
dry rapidly. If the grain is to be sown immediately,
dry only enough to permit of sowing, otherwise dry
completely. An accurate (tested) thermometer
should be used. Decrease the time by about 4
or 5 minutes for each degree in temperature above
those stated, but In no case exceed 129° F. for
barley and 131° F. for wheat. Increase the time
by the same amount for each degree below the
temperature recommended, but do not let the tem-
perature fall below 121° F. The grain should be
put in wire baskets and constantly agitated so that
the grains may all be heated. The temperature
should be watched closely and kept up to the de-
sired degree by additions of hot water.

6. Solution of Potassium Sulphide [Live?' of
Sulphur). — This solution loses strength on standing
and is best prepared as required for use in the fol-
lowing proportions : —

Potassium sulphide . . 2 oz.

Water . . . . .4 gallons

Mix In a wooden vessel and apply by means of
a syringe or sprayer on a calm day, to goose-
berry and rose trees which are suffering from
mildew.

7. Corrosive Sublimate Solution. — This solution
may be used as a preventive for scab, but it is now
in many cases supplanted by the more convenient.

32 FUNGOID DISEASES

and equally effective, formaldehyde solution. It
should be prepared in the following proportions : —
Corrosive sublimate . . i oz.
Water ... . . 7 gallons

For scab and other superficial diseases of the
potato, soak the tubers in this solution for ij
hours at least 4 weeks prior to planting. This
solution must be used for Rhizoctonia disease of
potatoes as formaldehyde solution is ineffective.
Corrosive sublimate is a deadly poison, and hence
care must be exercised in handling it.

8. FonnaldeJiyde SohUions. — As a preventive of
scab in potatoes, bunt and some smuts in grain,
solutions of formaldehyde have proved most effec-
tual. They should be prepared in the proportions
stated below.

(a) For Potato Scab.

Formaldehyde . i pint (40 per cent solution)

Water . . . . . y^i gallons

Place the potatoes in a coarse sack, immerse in

the liquid for about two hours, and then spread out

to dry. If very dirty the seed potatoes should be

washed prior to treatment.

(J)) For Smut of Oats and covered Sviiit of Barley .
Formaldehyde . i. pint (40 per cent solution)
Water ..... 30-40 gallons
Thoroughly sprinkle the grain with the solution,
using a watering can for the purpose while the
grain is being turned over on the floor, leave it in a

GENERAL INFORMATION 33

heap covered with canvas for several hours before
spreading out to dry. Another method is to put
the grain in a half-filled sack and dip it into the
solution, agitating to ensure contact of the solution
with the whole of the grains, then drain and spread
out to dry.

(c) For Bunt. — Pour part of the grain to be
treated into the formaldehyde solution ( i pint of
commercial formalin to 40-45 gallons of water), and
stir so that the bunted grains may all rise t(j the
top and be skimmed off and destroyed. Drain off
the solution into another vessel, then remove the
treated grain and spread out to dry. Replace the
solution, add more grain, and proceed as before.

9. Lime-SidpJmr Sohition. — This compound is
obtainable commercially in a concentrated form,
or may be made by the user. It is an excellent
contact insecticide, especially for scale insects on
fruit trees, but has also great fungicidal value and
can be used on some plants which cannot endure
copper fungicides (e.g. peach and Japanese i)lums).
It should not be used on potatoes nor on grapes.
If combined with poison for biting insects, the
best results are obtained by using arsenate of lead,
2-3 lb. of the dry powdered form, or twice as much
of the paste form, to 100 gallons of the solution.
As a winter spray lime-sulphur may be used much
more concentrated than after the foliage appears.
It should be tested with a Baume Hydrometer. It

3

34 FUNGOID DISEASES

is used largely for fruit trees, and fuller details re-
garding- its preparation will be found in books
dealing with diseases of fruit trees.

lo. Flowers of Sulpluir. — This is sometimes
dusted on the leaves to check mildew attack on
small areas.

Note. — For further information on spray mixtures and spray-
ing machinery, see " New York Exp. Station Bulletin," No. 243 ;
Pickering, Gimmingham, and Barker, I.e. p. 26 ; also " Standard
Fungicides," by G. F. Strawson (Simpkin, Marshall & Co.).

Classification of Fungi. — The Vegetable King-
dom (following Engler) is divided into twelve
divisions, the twelfth of which consists of seed-
bearing plants, and the tenth the true fungi. Per-
haps a more natural arrangement is that of
Professor Charles E. Bessey, who divides the
Vegetable Kingdom into fourteen Phyla. Of these
fourteen Phyla the last five represent different
groups of seed-bearing plants. Fungi are found
in two distinct Phyla, viz. : Siphonophycece, which
consists of two classes of green alg^e and one class
{Phy corny cetecs) of fungi, and CarpoinycetecB (the
Higher Fungi) containing three classes : Ascomy-
cetece (or AscosporecE), Basidiomycetece (or Basidio-
sporece), and Teliosporece.

The Phy corny cetece have no direct relationship
with the Higher Fungi, but rather with the green
algae belonging to the other classes of the Phyltim
— Siphonophycece ; while the Higher Fungi have

GENERAL INFORMATION 35

their closest relationship with the red seaweeds
forming the sixth Phylimi—RJiodophycece.

Besides these four classes of funo^i there occur in
some other classes of normally green algce a few-
representatives that have assumed the fungus
habit, e.g. the Synchytriacece in Class Protococ-
coidece in the Phylum Chlo7vphycece.

The four chief classes of fungi, however, are dis-
tinguished as follows : —

Class PhycomycetecB (Lower Fungi). Vegetative
hyphee without cross walls (except in old age,
after injury, or to set-off the reproductive organs).
There are four orders : —

{a) Saprolegniales with five or more families.

{b) Peronosporales with two families.

{c) Mticorales with four or more families.

(^d) Entomophthorales with one or two families.

Class Ascornycetece (Sac Fungi). Vegetative
hyphse septate. Perfect stage of reproduction
characterized by the formation of ascopores (usually
eight in number) in ovoid or cylindrical sacs called
asci. There are fifteen or more orders, and over
one hundred families ; many of them are important
parasites, and some form the organisms known as
lichens.

Class Basidio)nycetece. Vegetative hyphaj septate.
Perfect stage of reproduction with (usually four)
basidiospores formed on short or long stalks (sterig-
mata) from ovoid or club-shaped basidia. There

0

36 FUNGOID DISEASES

are nine or more orders and twenty to twenty-five
families. The common mushroom, puff-ball, and
bracket or ear fungi belong to this group.

Class Teliosporece. Vegetative hyph^e septate.
Parasitic for the whole, or most of the life cycle.
Perfect stage of reproduction by the production of
teliospores (teleutospores or sometimes chlamydo-
spores) which bear on germination a short pro-
mycelium on which are borne sporidia. This class
is often merged with the preceding as a sub-class in
which the pro-mycelium and sporidia are called
basidium and basidiospore respectively.

Two orders — Ustilaginales the smuts (with two
families, Ustilaginacece — the smuts, and Tilletiacecc
— the bunts), and Uredinales the rusts with three
families.

Besides these there is recoo^nized an artificial
group, the Fungi Imperfecti, consisting of fungi of
which only the vegetative or conidial stage is
known, the perfect stage probably belonging most
frequently to the Asconiycetece but in some cases
to the Basidiomycetece. There are three or four
orders and about ten families.

The accompanying table represents a schematic
arrangement of the Vegetable Kingdom, illustrating
by the relative areas of the classes the relative
number of species in each, while the solid lines
represent their probable relationships within the
various phyla and the broken lines the probable

GENERAL INFORMATION

.-)/

f 13

I Til

Fig. 7. — Schematic arrangement of the vegetable kingdom ; for explana-
tion see p. 38.

38 FUNGOID DISEASES

relationship of the phyla. The classes represented
by the shaded areas are those that are chlorophyll
bearing, while the classes of fungi are left unshaded.
Classes 1-7 and 9-14 are aquatic, being the Algce ;
18 and 19 are respectively Mosses and Liverzvorts ;
20-26 inclusive are Ferns and Fe7it allies ; 28 are
Cycads ; 31 are Conifers ; 32 Monocotyledons ; and
33 Dicotyledons. Class 8 is the Phycomycetece ; 15
the AsconiycetecB ; 16 the Telio spore ce ; and 17 the
Basidiomycetece ; while F.L represents the Fungi
Imperfect i.

The classes omitted (22, 24, 27, 29 and 30) are
chiefly fossil plants, so that their relative size
cannot be shown on the table, which aims to show
the relative number of species now existent.

CHAPTER II.

FUNGOID DISEASES OF CEREALS AND GRASSES.

I. Smuts. Class: Teliospore^ ; Order: Us-
TiLAGiNALES ; Family : Ustilaginace^.

Smut is also known to the farmer as dust brand,
chimney sweeper, sleek, slean, etc.

The cause of all smut of the small o-rains was
previously set down to a single species to which the
name Ustilago cai^bo was given : recent research
has shown that the smut of different trenera of
grasses is caused chiefly by species of Ustilago, but
in many cases of other genera as well. The econ-
omically important forms, however, are mostly
species of Ustilago.

(a) Oat Smut i^Ustil ago Avence)} — Much damage
is caused in certain districts by this fungus.

Symptoms. — Plants which up to the time of the
appearance of the ear have looked quite healthy
are found to produce, instead of grain, a brownish
black powder, which is easily carried and distributed
by the wind, leaving nothing but the bare straw at
harvest time.

' A closely related species, U. Icevis, has been found along with
this species, the spores of which are perfectly smooth.

39

40

FUNGOID DISEASES

Ca7ise. — Examined under the microscope the
above brown powder is found to consist of myriads
of spores (chlamydospores or teliospores) of the
fungus Ustilago AvencB.

Each spore is rounded and has two coats, but the
spores are free from the fishy odour which accom-

A B

Fig. 8. — Oat smut {Ustilago Aveim) : (A) Portion of healthy ear of oats;
(B) Portion of smutted ear ; notice that the spikelets are very irregular
in shape and blackened with the spores of the fungus.

panics the spores of bunt (see p. 47). The spores
germinate readily in water, and dung heaps also
form a suitable medium for arowth.

Since the spores are distributed before harvest,
some are blown on to the healthy ears, but no de-
velopment takes place until the grain is sown the
following spring. The grain and the spore germin-

DISEASES OF CEREAES AND GRASSES 41

ate together, the former producing" a young plant,
the latter a short hypha, the pro-mycelium (see Fig.
9, A) and conidia.

The conidia, on trermination, form a eerm tube
capable of penetrating the tissues of the oat plant,
but only at this young stage. The plant suffers no
apparent effect from the intruder. Hecke, however,

Fig. 9. — (A) spores of Ustila^o Avencr : (B) a spore germinating in
nutritive solution ; notice the septate pro-mycelium (/>) with the oval
conidia (c) at the side; (C) spores of Tillctia Tritici : (D) the same
germinating, producing a short pro-mycelium with a wisp of long
conidia (/) at the end. (Magnified about 300 times. After Brefeld.)

has shown that the ear may be infected by moisten-
ing with water containing smut spores ("Journal
B. of Agr.," Feb., 1906, Vol. 12, [)ag(^ 699).
The hyph:e grow actively in the growing [)oint of
the stem, and when the ear begins to be formed,
they break up to form the sooty powder (i.e. the
spores), thus revealing the presence of the para-
site,

42 FUNGOID DISEASES

Preventive Measures. —

1. Copper solutions, p. 28.

2. Hot water treatment, p. 29.

3. Formaldehyde treatment, p. 32. This is the
best of all.

(K) Barley Smiits^ — (i) Naked or loose smut
{Ustilago nuda) = U. Hordei {^rd) ; (2) covered
smut ( Ustilago Jensenii ( Rostr .)) .

(i) Naked Smut. — Of the two this is the more
common in Great Britain. The spores are dis-
persed before harvest. Infection takes place
through the flowers, the mycelium entering- the
ovary, where the grains become infected. The
diseased grain produces a plant in whose growing
point the fungus progresses, destroying the ear
when formed.

Prevention. — Treatment, to be effective, must de^
stroy the fungus within the grains without injuring
the vitality of the latter, this is possible with the
modified hot-water treatment of Jensen. (See fur-
ther note under wheat smut.)

(2) Covered Snint. — Here the bulk of the spores
is not distributed before harvest. The ear may re-
main within the upper part of the sheath practically
intact, except that instead of the healthy grain, smut
spores are formed and surrounded by the fertile
glumes. Infection takes place at the seedling stage
from spores adhering to the grain, hence treatment
of the grain with fungicides is effective.

Prevention. — Treat the grain prior to sowing

DISEASES OF CEREALS AND GRASSES 43

with ^ per cent solution of copper sulphate (see
page 29) or with formaldehyde solution (p. 32).

(c) Wheat Smut { Ustilago Tritici)^

This is sometimes called loose smut, and must
not be confused with bunt (stinking smut) (see p. 45).
The mycelium uses up not only the nutriment in-
tended for the development of the grain, but the
chaff is also attacked.

Prevention. — Difficult to combat, as copper or
formaldehyde solutions are apparently
ineffective. It can, however, be com-
pletely controlled by the use of the
modified hot water treatment (p. 30).
Inasmuch as this is a slow process —
not more than 8-10 bushels of grain
can be treated in a day, — it is sug-
ofested that sufficient grrain be treated
each year to plant a plot of two or
three acres from which the seed for
next year's sowing may be obtained.
This seed plot should be planted away
from other fields of wheat so as to
avoid infection of the seed at blossom-
ing time by the spores carried by the
wind from such other fields.

(d) Rye Snint ( Urocystis occultci).

This is seen in the form of grey stripes, mostly
on the stem but also on the leaves, which latter
burst and expose the black spores (Fig. 10).

Img. 10. — A ball
of spores of
Urocystis oc-
cnl t a ( r >■ e
smut). In the
centre the dark
fertile spores,
one of which
has sent out a
short pro-my-
celium (/>) ;
these are sur-
rounded by
sterile spores
(s). (Highly
maojnified.)

44 FUNGOID DISEASES

The germ tube is said to be only able to enter
the plant in the young stage.
Prevention . —

1. Steep seed in copper solution (p. 28).

2. Jensen's hot water treatment (p. 29).
Results from the treatment of the seed are by no

means uniform.

Note. — i. Rye smut caused by Ustilago Secalis is very rare. It
destroys the whole ear.

2. Urocystis Agropyri forms black bands of spores on couch
grass, hungarian forage grass, etc.

(^) Maize Snnit {Us til ago Maydis)-
None of the fungi above described cause such
malformations as U. Maydis- Not only the grain
but every part of the plant is attacked. First white
wrinkled patches appear, which swell, and later
burst, thus liberating the spores. It is definitely
known that the plant can be infected at a late stage
of growth as well as in youth.
Preventive Measures. —

1. Sow grain from fields not badly infected.

2. Remove by hand, and burn, the smut masses
before they burst.

3. Avoid, as far as possible, planting maize on
fields where smut was serious the preceding year.

(y) Brome Snmt ( Ustilago broviivord).

While the above fungus may check the growth of
the undesirable grass {^Bromtts mollis) to some extent,
in those meadows where it is found in abundance,

DISEASES OF CEREALS AND GRASSES 45

still this smut, like the rest, must ])e looked upon as
all undesirable quantity. The amount of the brown
powder (smut spores), shed on the g"rass and hay,
causes the latter to become so black as to make it
doubtful whether it is wise to feed such hay to
stock. The oflumes — chaff — are said not to be
attacked, but the writer has seen whole areas of
smutted brome grass with the glumes also attacked ;
perhaps this was caused by a variety of the above
species. Instead of the grass seed a mass of spores
is produced.

Prez 'eiUive Measu res, —

1. Soft Brome {Broniits mo//is) is an undesirable
annual plant, therefore pasture for a year or two,
and keep from seeding.

2. Apply manures to improve the quality of the
herbage.

(o-) Tall Oat Grass Smut ( Ustilago pcrciuians) .

This is widespread and of frequent occurrence.
The mycelium rests over winter in the rhizome,
i.e. below the surface.

Prevention. — Hot water treatment of the seed

(P- 29)-

II. Bunt {Tilletia Tritici'), Class: Telios-

PORE.E ; Order : Ustilaginales ; Family : Til-

LETIACE/E.

Bunt, or, as it is sometimes called, stinking

1 Kiihn describes a species T. licvis, which causes bunted grains,
and differs from T. Tritici only in having smooth spores.

46

FUNGOID DISEASES

smut, is one of the most objectionable diseases of
cereals. It destroys a number of ears, and at thrash-
ing the remaining healthy grains
become covered with the black
spores, thus spoiling the taste and
colour of the flour made therefrom ;
while the straw and chaff are made
distasteful to stock.

Symptoms . — It is only with
difficulty that bunted ears can be
distinguished from healthy ones at
harvest time. The bunted ears
are broader, the glumes more open,
and the grains have a greyish colour
(see Fig. ii). The opening of
the glumes is due to the increased
breadth of the bunted ^rain en-
cased within (Fig. 12, B). Some-
times the grains are cracked ; this
reveals the inner contents, viz. a
black mass of spores of the fungus.
These spores have a strong fishy
odour due to the presence of tri-
methylamine.

Catise. — The bunted orrains are
caused by the formation of the
spores of the fungus (Zl Tritici) from mycelium
which had entered the wheat plant in the early
stage and grown up with it.

I'lG. II. — A diseased
ear of wheat show-
ing the dark col-
oured bun ted grains
enclosed within the
glumes (somewhat
diagrammatic).

DISEASES OF CEREALS AND GRASSES 47

The spores are fairly large and round, with a
reticulated surface (see Fig. 9, C and D).

According to Kiihn the germ tube from both the
primary and the secondary conidia is able to enter
the host plant, grow within its tissues, and, at the
time of grain formation, produce bunted ears.

A B C

Fig. 12. — Grains of wheat: (A) shows the shape of the healthy grain;
(B) shape of a bunted grain ; note how much broader it is than the
healthy one ; (C) longitudinal section of a bunted grain showing the
black mass of bunt spores enclosed.

Some of the differences between smut and bunt
are enumerated below : —

Smut.

Spores distributed before

harvest.
Spores small, coats

smooth.
Spores odourless.

oerminate

c5

in
nutritive

Spores

water and
media.

Germinating spores pro-
duce a four-celled pro-

BUNT.

Grain still intact at har-
vest.

Spores large with reti-
culated coats.

Spores strong hshy
odour.

Spores germinate in
water but not in nutri-
tive media.

Pro-mycelium shorter,
conidia longer and in

48 FUNGOID DISEASES

Smut. Bunt.

mycelium with oval a group at the end

coiiidia at the side (Fi^- 9» C).
(Fig. 9, B).
Conidia multiply by No budding of conidia.
buddintr.
Preventive Measures. —

1 . Treat with copper solution (see p. 28).

2. Hot water treatment (see p. 29).

3. Treat with formaldehyde solution, which is the
most satisfactory and is easily applied (see p. 32).

Note. — Various species of Tilletia attack the leaves and fruits
of other cultivated plants, but space does not allow of their descrip-
tion.

III. "Rusts." Class: Teliosporej-: ; Order:
Uredinales.

Enormous damage is done annually to our wheat
crops by the ravages of the rust fungi ; and this
notwithstanding that there are varieties of wheat
on the market which are practically resistant to the
disease. It is earnestly to be hoped that the
efforts of the biologist at the School of Agriculture,
Cambridge University, to obtain, by crossing, rust-
resisting varieties possessed of that "strength"
which the miller desires, will be crowned with suc-
cess. Since the above was written a variety (Little
Joss) having these qualities has been obtained.

A few of the most important rusts are described
below.

DISEASES OF CEREALS AND GRASSES 49

(a) Rztst and Mildew of Wheat [Puccinia gram-
inis).

Many varieties of wheat are attacked.

Symptoms, — The leaves of attacked plants turn
a pale yellow colour in early summer, and later
elongated reddish-orange spots appear on the leaf,
sheath, and the stem. These spots turn a much
darker colour in the late summer (see Fig. 13).

Fig. 13. — Rust of wheat {Pnccinia graminis) : (A) showing the small
pustules covering the wheat leaf; (B) section through a pustule from
(A); (») uredospore ; (t) teleutospore ; (5) surface cell of wheat leaf.

Cause. — This disease is caused by the fungus
Puccinia graminis, which has a very interesting,
but complex, life history ; for it apparently usually

4

50 FUNGOID DISEASES

utilizes but probably does not require two host plants
on which to complete its life cycle (see p. 51).

The reddish-yellow pustules above mentioned are
due to the fungal threads breaking through the
epidermis and bearing the orange-coloured spores
called uredospores (Fig. 13, B). These are the
summer spores ; they are thin walled, light coloured,
and one celled, and are easily carried by the wind
to healthy wheat plants, on the leaves, leaf sheaths,
and stems of which they germinate. They send out
a oferm tube which enters and ramifies within the
tissues, branches and rebranches, finally breaking
through the surface and producing the yellow
pustules.

The darkening of the pustules is due to the for-
mation of another kind of spore — teleutospore or
teliospore — from the same mycelium (see Fig. 13, B).
These teleutospores are longish oval, two celled, and
have a thick outer wall They are borne on a stalk
about the same length as the spore, and rest over
winter. In the spring they germinate, each cell
sending out a hyphal thread which branches at the
tip and forms four sterigmata, on each of which a
conidium (sporidium or basidiospore) appears. This
basidiospore appears to be incapable of infecting the
wheat plant, but it is able to penetrate the leaf of
the barberry [Berberis vulgaris), develop within,
and in a short time produce small flask-shaped bodies
called spermogonia on the upper surface of the leaf.

DISEASES OF CEREALS AND GRASSES 51

•
These contain spores, but their use is not definitely

known. On the under side of the leaf, at the
same time, cup-like openings appear, called cecidia.
These eecidia are seen as reddish-yellow raised
patches, and they are filled with ai^cidiospores.
The secidiospores are roundish cells with smooth
outer coats ; they retain their power of growth for
a short time only. They may germinate on the
barberry leaf, but the germ tube does not enter ;
if, however, they are carried by the wind to the
stem or the leaf sheath of the wheat plant, the
germ tube readily enters the inner tissues, develops,
and in the course of 8 to 10 days aerial hyphae
break through the surface and bear at the tip the
uredospores ; which in mass appear as red pustules.
These uredospores are readily carried by the wind
to healthy wheat plants, thus causing infection.

Experiments in America have demonstrated that,
in that country at least, the rust is able to survive
the winter on the over-wintering wheat plants, pro-
ducing an abundance of uredospores in the spring,
so that the presence of the barberry is not an es-
sential for the maintenance of the disease. Indtted
it has been found that sometimes the mycelium
remains alive in the seed, and so infects the new
crop.

Note. — According to Erikson there are six biological varieties
of P. gramijiis^ each having its ascidial stage on the barberry.

For preventive measures see p. 54.

4*

52 FUx\GOID DISEASES

(b) Golden or Spring Rust [Ptcccinia glu-
niarimi). (Fig. 14, C and D). This rust was pre-
viously considered as a variety of P. riibigo vera,
but Erikson, as a result of inoculation experiments,
considers it a distinct species with several bio-
loofical varieties.

The roundish uredospores appear on the leaves
of grasses, in the form of lemon to cadmium coloured
irregular pustules or sori. These sori may spread
longitudinally, forming ultimately yellow linear
markings. The teleutospores are sparse, and in
the form of fine brownish-black stripes.

The teleutospores are set on short stalks and
germinate in the autumn of their formation. The
pro-mycelium is of a bright yellow colour — this dis-
tinguishes it from Puccinia dispei'sa — which colour
disappears on the formation of the sporidia.

The cecidial stage is unknown.

Although abundant in spring, the damage done
is not serious.

For preventive measures see p. 54.

(f) Broivn Rust {Puccmia rubigo vera = Puccinia
straminis, Fuckel ; Pnccinia dispersa, Erikson).

This rust is found chiefly on the leaves of rye,
wheat, barley, and various grasses, in the form of
rust-red, roundish, scattered patches. The uredo-
spores are much rounder than those of P . graviinis.

The teleutospores are present in the same pustule,
in fact, spring from the same mycelium ; they are

DISEASES OF CEREALS AND GRASSES

3:)

not so dark in colour as those of P. graininis, have
a much shorter stalk, and are not covered with a
crown of paraphyses or hairs.

The secidia are found on the bugloss, but are
not essential, for uredospores may be found on
young wheat and rye plants in the autumn, and the
mycelium is undoubtedly able to rest there over
winter, as well as in various grasses, and on account
of this is most difficult to combat.

A

Fig. 14. — (A) uredospores of Piiccinia graminis ; (B) teleutospores of
Piucinia gi'aininis : (C) UTcdohi^ores oi Pticcinia gliiiiuintHi : (D) tel-
eutospores of Puccinia gluniariim ; (E) uredospores of Piicciiiia
coroiiata ; (F) teleutospores of Puccinia coronatd : notice the crown
of spiney projections at the end. (All highly magnified.)

For preventive measures see p. 54.

(d) Barley Rust [Ptcccinia suiiplex, Korn).
Attacks barley, but the damage is only slight.

The teleutospores are mostly one celled.

(e) Crown Rust of Oats and Grasses [Puccinui
coronata, Corda).

54 FUNGOID DISEASES

By inoculation experiments Klebahn has shown
that there are two distinct species, viz. : —

(i) Puccinia coronata — found on many grasses,
especially Dadylis glomerata (cocksfoot)
and Festuca silvatica, a variety of sheep's
fescue,
(ii) Puccinia coronifera — which occurs on
various grasses, and also on oats, but not
on wheat and barley.
The uredospores of P. coronifera are found on
the upper surface of the leaf of oat plants, in the
form of small orange coloured sori. The teleuto-
spores are in the form of minute greyish black spots,
and are characterized by a crown of spines around
the end cell ; hence the name ''crown rust" (see
Fig. 14, F). Apparendy they are not able to ger-
minate until the spring.

The aicidiospores are found on the buck-
thorn.

Preventive Measures. — Owing to the di\'ersity of
spore formation, and to the mycelium being within
the plant, the various rust diseases are most difficult
to combat. Spraying and pickling of the grain
are quite out of the question, hence any recom-
mendations must of necessity be of a general
character.

1 . Avoid heavy dressings of nitrate of soda, give
small amounts along with superphosphate.

2. Select varieties which show least susceptibility

DISEASES OF CEREALS AND GRASSES

D!)

to rust and still maintain the other essential char-
acters, e.g. Little Joss.

3. Sow autumn grain somewhat late, and put in
spring sown early.

4. Drain the land.

5. Climatic conditions have their influence, but
are beyond control,

Note. — A large number of rust fungi attack various garden
plants and would have been described had space allowed.

IV. Ergot {Claviceps purpurea). Class: As-
COMYCETE.E ; Order : Pyrenomycetales,

Found on cereals and grasses, but especially
common on rye and rye grass. This fungus pre-
vents healthy development of the grain, and the
sclerotia contain poisonous substances — ergotin and
cornutin^ — -which are said to be injurious to stock.

Symptoms. — -Ergotted ears have large black
bodies — the sclerotia — taking the place of some ot
the grains, and projecting beyond the other parts,
making diseased ears easily recognizable (Fig.

15. A).

Cause. — The above sclerotia are the resting
bodies of the fungus Claviceps purpurea which has
taken up its abode in the ear, thus causing the
disease. \\\ early winter they fall to the ground,
and can withstand drought and cold, hi spring
they germinate ^ in the soil, giving rise to numerous

^ May be collected and germinated in the laboratory in moist
sand.

56

FUNGOID DISEASES

mushroom-like outgrowths called stromata (see
Fig. 15, B) with violet stalks and yellow heads.

These heads contain numerous flask-like bodies
— perithecia — with the narrow part pointing out-
wards (see Fig. 15, C and D) and containing
numerous asci (spore cases). Each ascus encloses

Fig. 15. — (A) Ryegrass affected with Claviceps purpiii'ca : (5) sclerotiuni ;
(B) germination of a sclerotium (s^) stroma ; (C) longitudinal section
through a stroma showing the perithecia (/>) containing asci ; (D)
perithecium more highly magnified showing the position of the asci
(a); (E) an ascus very highly magnified; (5) the ascospores. (After
Tulasne.)

eight long, slender ascospores (Fig. 15, E). When
the ascospores are carried by the wind to the base
of the floret of the host plant, they send out a
germ tube which enters the ovary and produces at
the same time a mycelium externally bearing
numerous conidia. A sugary substance is secreted

DISEASES OF CEREALS AND GRASSES

D/

by this mycelium — sometimes called the honey
dew stage ; this entices bees, which carry away, on
their legs, the conidia to healthy grass tlowers,
where they readily germinate, enter the ovary,
form honey dew and conidia, and, like the first
mycelium, when the food supply becomes ex-
hausted, i.e. towards autumn, form the sclerotia by
interlacing and repeated branching. The shrivelled
ovary may often be found at the end of the
sclerotium.

Preventive Measures. —

1. Collect as many sclerotia as possible and sell
to the chemist.

2. Do not allow grass in pastures and waste
places to seed.

3. Cut, collect, and burn grass parcels which are
ergotted.

4. Drain land well and improve the herbage so
that it will be well eaten down.

5. Sow seeds free from ergot.

V. Smother Fungus of Grasses [Jipic/i/oe
typhina). Class: Ascomycetej: ; Order: Pyrkno-

MYCETALES.

This is frequently found in abundance on many
grasses, especially meadow foxtail [A/opciiinis
pratensis) and cocksfoot {Dactylis glovicrata), and
although not a serious pest, it is said to be injurious
to horses if eaten in abundance.

Symptoms. — The upper leaf sheath becomes sur-

58 FUNGOID DISEASES

rounded by an ochre-coloured collar, or muff-like
growth, consisting of a felt of fungus hyphae.
These hyphae penetrate the sheath and stem,
filling up the spaces between the two. The part
is quite hard when cut through.

Cause. — The collar-like growth is caused by the
fungus Epichloe typhina, the hyphae of which en-
circle and penetrate the sheath and stem. The
colour of the collar darkens with age.

Preventive Measures. — Very difficult to combat,
little beyond cutting down and destroying attacked
oTass can be recommended.

VI. Wheat and Grass Mildew [Erysiphe
gramims). Class : x\scomvcete.« ; Order : Peri-

SPORIALES.

Wheat suffers to a larger extent than grasses.

Symptoms. — During the summer months die
leaves of grasses and wheat become covered with
greyish-brown, irregular, felt-like patches on the
upper surface, consisting of the mycelium of the
fungus Erysiphe graminis. Short hyphee arise,
bearing conidia in chains (see Fig. i6, C).

Cause. — The cause of the peculiar grey covering
is the presence of the mycelium of Erysiphe. The
oval spores are readily carried in the atmosphere
to the surface of the leaves of healthy plants, where
they germinate and set up new^ centres of infection.

In autumn small dark-coloured bodies, visible to
the naked eye, appear on the same threads that

DISEASES OF CEREALS AND GRASSES 59

bore the conldia ; these are the perithecia contain
They remain

ing asci.

attached to the leaves
until the spring, when
they liberate the asco-
spores, which on ger-
mination again produce
the disease. But even
failing these perithecia,
the fungus may be found
on the wheat plant in
winter, where it un-
doubtedly can remain
until the spring.

Preventive Measu res .
— Unfortunately very
little can be done.

1. Small areas may be dusted with llowers of
sulphur, but this is too costly and impracticable for
field crops.

2. Spring sowing is said to be an advantage.
VII. Discoloration Due to Funci.

{a) Broivning of Wheat Leaves. — This browning
of the leaves is of somewhat frequent occurrence
on the Continent.

Symptoms. — Appears in spring on winter sown
wheat : the leaves turning somewhat yellow at first,
and later more to the brown, while hnally they dry
up. On the brown surface small black spots may be

Fig. 16. — Portion of the hyphai ;
(H) of Erysiphc ^raniinis bear-
ing the oval conidia (C) in chains.
(Highly magnified.)

6o FUNGOID DISEASES

found, by means of a pocket lens ; these are the
fruit capsules of the fungi present.

Cause. — According to Frank the eight fungi
enumerated below, which are much alike externally,
contribute to the cause of this disease : sometimes
singly, sometimes several of them being concerned.

(i) Septoria graniijieum, Desm.

(2) Septo7'ia briosiana, Morini.

(3) Septoria ghunaruni^ Pass.

(4) Septoria avencB, Frank.

(5) Ascochyta graminicola, Sacc.

(6) Phoma Heiniebei^gii, Kiihn.

(7) Leptosphceria Tritici, Pass.

(8) SphcB7^ella exitialis, Morini.

Some of the above fungi may also be concerned
in the blackening of the grain.

Little can be done in the way of prevention.

[b) Leaf Brown of Barley [Hchninikosporin?n
gram inemn , Erik.).

This disease is very prevalent on the leaves of
barley on the Continent, and many crops in England
suffer from the same cause. Potter has shown
that it is the cause of " deaf ears" in barley.
-Symptoms. — Elongated, dark, brownish-olive
patches with yellowish circumferences appear on the
leaf while it is still green ; these spread, especially
lengthwise, destroying the tissues until the whole
leaf becomes discoloured, dried, and split up into
ribbons. The under leaves are attacked first, and

DISEASES OF CEREALS AND GRASSES 6i

may be very badly infested before the ear appears.
In bad attacks the ear never gets out of the sheath.

Cause. — The appearance of this disease is often
due indirectly to adverse weather conditions
weakening- the plant, but directly to the fungus
H . gramineimi, which penetrates and destroys the
tissues. How winter is passed over, and how in-
fection takes place the following spring, is not
known.

Preventive Measures. — No definite means of pre-
vention are known. Spraying with different fungi-
cides has been carried out at Cambridge, but the
results are not very promising.

{c) Blackening of Straiv and Black-ended Inxrlcy
( Cladosporiu77t herbarM7n ) .

Fungi hnperfecti ; Order

With humid weather
conditions the straw of
wheat, oats, and barley
becomes a black or greyish
colour. In some cases the
o-rain also becomes black-
ened, hence the term
" black-ended barley " (see
Fig. 17); such barley being
considerably reduced in value.

Cause. — With moist conditions the mycelium of
C/adosporiMm herbarum grows abundantly on and
in vegetable matter. This fungus is widespread.

M ON I U ALES.

Fig. 17. — Black-ended barley :
(A) healthy grain ; (H) black-
ended grain, caused by the
fungus Clatlosporiiiiii her-
bnrnm.

62 FUNGOID DISEASES

It causes the blackening of the moist cloths of the
cheese-maker.

P7'eventive Measures. — On account of the wide-
spread nature of the fungus and the uncontrollabllity
of the weather, little can be done to check this
ubiquitous pest. Crops in moist districts should be
cut early, and thrashed grain should be stored
perfectly dry.

{(i) Leaf Brown of Oats i^Helminthospoy'iuni
teres, Sacc).

Fungi Imperfecti ; Order : Moniliales.

Resembles in many respects barley browning,
except that infection commences at the tip of the
leaf, spreading downwards. The conidiophores are
sino^le, the conidia smaller and have a greenish

" nuance ".

A species of Helminthosporiuni causes a blight
on the leaves of maize.

{e) Grasses. — Small, raised, well-defined, oval
black spots, resembling in size and appearance " fly
droppings," are formed on the leaf blades of cocks-
foot and other grasses by the fungus Phyllachora
graminis. These black spots contain the peri-
thecia with their spores enclosed. Not of a serious
nature.

Note. — Space will not permit of a description of other minor
fungus diseases of grasses and cereals.

For diseases of plants coming under this section caused by insects,
see " Farm and Garden Insect Pests," bv Somerville. M.M. >k Co.

CHAPTER III.

FUNGOID DISEASES OF LEGUMINOUS PLANTS.

(Peas, Beans, etc.)

I. Mildews. —
(a) Mildew.
(/;) Mildew (false).
(c) Mildew (downy).

(a) Mildeiv{^Erysiphe Martii)} Class : Ascomv-
CETE^i ; Order : Perisporiales.

This fungus attacks various species of Pisuni,
Lathyi'us, Vicia, and Trifolmm ; especially to-
wards the end of summer, doing considerable harm.

Symptoms. — First observed as a snow-white
covering on the leaves while the latter are still
green, later this woolly covering of fungus mycelium
turns a dirty grey, and the leaf assumes a pale-
yellow sickly colour.

Cause, — Microscopic examination of a leal with
the above symptoms shows that the cause is the
presence of the fungus E. Alar Hi (not to be con-
fused with false mildew, p. 64). This fungus is

' This fungus also appears on certain cruciferous plants.

63

64 FUNGOID DISEASES

an obligate parasite^ ; when its spores germinate on
the surface of the leaf, the germ tube branches and
rebranches, forming the wool-like growth. The
mycelium does not enter the plant, but special
organs called haustoria (see p. 5) draw nutriment
from the host for the fungus. The spores are
formed in chains from short branches of the mycel-
ium, in a similar manner to E . graminis (Fig. 16).
When carried by the wind to the surface of healthy
leaves they readily germinate,^ thereby setting up
new centres of infection. Later small, brownish
bodies about the size of a pin's head are formed on
the mycelium on the surface of the wilted dying
leaves. These little bodies gradually become
black ; they are the perithecia containing asci in
which the ascospores are formed and enclosed. The
ascospores are set free and carried by the wind to
healthy young plants in the spring.

(h) False Mildew [PeronospoJ'a Trifoliomm and
Pe7'onospora vicice). Class : Phycomycete/E ; Order :
Peronosporales.

Peronospora Trifoliorum causes false mildew of
clover and lucerne especially, but is also found on
other plants.

P. vicicB causes false mildew on various leo^um-
inous plants, particularly vetches and peas. Both

^ The spores may be germinated on certain artificial media, but
the germ tube soon dies, in fact it is, up to the present, impossible to
grow the fungus as a saprophyte.

DISEASES OF LEGUMINOUS TLANTS 65

spread in dry weather as well as wet, and cause
considerable damage.

Symptoms. — Similar outwardly to those given
under true mildew above. A greyish white cover-
ing of mycelium is seen on the under surface of the
leaf, on the stem, and on the leaf stalk ; pinkish-
grey spots appearing when the spores are formed.
The attacked plants turn yellow and thrive badly.

Fig. 18. — False mildew of vetches — conidiophore of Pcrono%^ora V'lc'uc
growing through a breathing pore ; (C) the oval conidia. (Highly
magnified.) (After Tubeuf.)

Cause. — -The yellowish colour is due to the fLingus
hyphai ramifying within the tissue of the attacked
plant and depriving it of part of its nourishment
(compare Erysiphe, p. 63). Tree-like conidio-
phores grow through the breathing pores of the
leaf, and the conidia are formed at their tips ; these
are able to germinate immediately, and when trans-
ported may start new disease areas. Resting spores
with smooth coats are formed inside the diseased

5

66 FUNGOID DISEASES

tissue as a result of sexual union ; they are called
oospores, and germinate the following spring.

The above description holds good for P. vicice,
except that its oospores have a reticulate thickened
outer wall.

(c) Downy Mildew (^Phytophthora Phaseoli).
Class : Phycomycete^ ; Order : Peronosporales.

Damage to beans and peas may be serious,
other plants are also attacked. Greyish-white
patches of mycelium appear on the leaves, stems,
and pods ; from this mycelium conidiophores arise
which bear spores in a similar manner to Phyto-
p ht ho 7'a infest mis (see Fig. 21, B, p. 76). The my-
celium also penetrates the inner tissue, from which
it derives its nourishment.

Prevention of the dijferent Mildeivs. —

1. Mow infected clover crops to save what

remains of them.

2. Spray with Bordeaux Mixture, repeating

every fortnight.

3. Washes of potassium sulphide are very

effectual, but too expensive.

4. Burn badly diseased parts.

5. For attacks of Erysiphe on small areas

dust with flowers of sulphur.

6. Drain the land well, for first attacks are

usually in moist places.
II. Rusts. Class: Teliospore^; Order: Ure-

DINALES.

DISEASES OF LEGUMINOUS PLANTS 67

{a) Clover i^Uromyces^ apiculatus, Schrot. ; U.
Trifolii, Heel.).— Common on red, white, and alsike
clover. On white clover uredo-, teleuto- and
aecidiospores are formed, while on the other two,
uredo- and teleutospores only. The mycelium
causes thickening- and wrinklino- of the stalk and
veins of the leaf.

(/?) Beans {U. pkaseohvitni).— AW three kinds of
spores are formed ; haricot and scarlet runner
beans are chiefly attacked.

(6") Peas [U. pisi). — Uredospores and teleuto-
spores are formed on different species of Pisitin,
Latkyrus and Vicia, aecidiospores on the s[)uroe
{Eicpkorbia).

(d) Lucerne {(J. siriatus, Schroeter). — Causes
rust spots on various species of Medicago, due to
the formation of uredo- and teleutospores. The
aecidiospores are formed in the spurge.

Preventive Me as n res . —

1. Burnino- of infested areas is recommended

in each case but is impracticable.

2. Sow early.

3. Keep down such weeds as spurge.

III. ScLEROTiuM Disease of Clovers (Scleral inia
Trifolioruni). Class : Ascomvcete.e ; Order : Pe/i-

ZALES.

This disease causes more harm to our clover

^ The genus Urotnyccs differs from Puccinia in having one-celled
teleutospores.

5*

68

FUNGOID DISEASES

crops than is generally imagined, for only when it
breaks out as an epidemic is any notice taken of it.
Symptoms . — The attacked plants turn yellowish
without any visible sign of the cause, and gradually
die off. On examination of the dead parts, especi-
ally the root and part of the stem at, or near, the
ground surface, the sclerotia may be seen as small
black button-like growths (Fig. 19, A, sc).

Fig. ig. — Sclerotium disease of clover: (A) portion of clover root with
sclerotia {sc) attached ; (B) a sclerotium germinating ; {t) the
trumpet-shaped stroma containing the spores ; (s) the soil level.
(After Frank.)

Cause.— ^\\^ cause of the plants dying is the
presence in their tissues of the fungus Sclerotinia
Trifoliorum. This mycelium absorbs its food
supply from the clover plant, thereby causing
gradual starvation. The plant ultimately dies and
shrivels up, and the fungus, in order to prepare for
emergencies, forms sclerotia. These sclerotia can
rest over winter, in fact are capable of growth after
being kept dry for two or three years. Under

DISEASES OF LEGUMINOUS PLANTS 69

favourable conditions they germinate the following
summer, giving- rise to yellowish-brown trumpet-
shaped growths (see Fig. 19, B). Inside the trum-
pet shaped openings are numerous asci standing
erect and side by side. The ascospores are capable
of immediate germination, but their germ tube is
unable to enter direct and live parasitically, until
strengthened for a time by saprophytic nourishni(tnt.
Preventive Measures. —

1 . Collect and destroy attacked plants.

2. Do not grow clover too often on the same

land.

IV. Spot Disease of Peas {Ascochyta pisi).

Fungi hnperfecti ; Order: Spileropsidat.es,

Peas, possibly lucerne and other leguminous
plants, suffer from this disease.

Symptoms. — Brown spots appear on the pods
(see Fig. 20, s\ leaves, and on the stems, at first
near the ground, but later on all parts. These
diseased areas on the stem often penetrate to the
water-conducting tissues and cause the plant to die
with symptoms of a "wilt disease". On the dis-
coloured areas, minute black dots (the picnidia or
spore cases of the fungus) appear. On the |:)od, the
spot may penetrate from one side to the other, de-
stroying the enclosed seed, or the seed may be
infected without killino- it, so that some (only a low
percentage) will germinate, thus carrying the
disease over to the following year.

70

FUNGOID DISEASES

Cause. — The disease is caused by the parasitic
fungus Ascochyta pisi, which destroys the tissues,
producing discoloured spots. The disease is trans-
mitted in infected seeds (see Fig. 20, c and b), and
also in the diseased stems and leaves, if these are
allowed to remain on the around over winter.^

Fig. 20. — Pod of pea suffering from Spot Disease [Ascochyta pisi) (s) ;
below a cotyledon (half of a pea) (r) with diseased centre (d).

Preventive Measures. —

Sow seeds from healthy plants, or from
fields not affected ; if suspicious of the
seed, sow only plump unspotted seeds.

Do not grow peas two years in succession
on the same field.

^ Beans, particularly haricots, suffer from a disease known as
anthracnose, and caused by Colletot?-ichuni Ii7idemiithia77um. This
causes brown spots on the pods, seeds, and also on the stem of
seedling plants, as well as brown lines along the leaf veins. It is
not easily controlled, but the same methods should be adopted as
for the spot disease of peas.

DISEASES OF LEGUMINOUS PLANTS 71

3. Remove and burn all plants at the close of
the season.

V. Violet Root Rot of Lucerne i^Rhizoctonia
violacea) . — Fttngi Imperfecti,

According to Kiihn, various other plants are
attacked, including potatoes, red clover, beet,
mangels, carrots, etc., but apparently cereals are
not susceptible.

Symptoms, — Yellow patches appear in the crop
quite suddenly. Plants uprooted from such patches
v/ill be found to have the roots covered with a
brownish-violet ofrowth. In a bad case the stems
may also be attacked.

Cause, — The facultative parasite Rhizoctonia
violacea is responsible for the yellow appearance of
the crop and violet covering of the roots. It
spreads its mycelium over the tap and side roots,
some of the threads penetrating the inner tissue,
thereby robbing the plant of nourishment, and
finally killing the roots and causing the falling of
the plants.

So far no spore formation has been noticed,
but sclerotia may be found. The mycelium can
spread from plant to plant. The fungus doubtless
belongs to the Basidiomycetes.

Preventive Measitres. —

1. The fungus grows best on sour soil, therefore
sweetening the land by liming checks its growth.

2, For the same reason drain land well.

72 FUNGOID DISEASES

3. Keep down weeds which may act as food
when other plants are lacking.

4. Dig over diseased spots deeply and apply
carbon-bisulphide.

5. Grow cereals on the land for a year or two.

6. Remove all diseased parts where this is prac-
ticable.

(See "Journal of the Board of Agriculture," Vol.
12, No. II. Tubeuf, p. 219. Minnesota Plant
Diseases, p. 329. Massee, p. 345.)

VI. Other Diseases of Lucerne and Clover.

(a) Disease of Crown of Roots [Uropklyctis
alfalfce). Class : PHYCOMVCETEiE ; Family : Clado-

CHYTRIDIACE^.

The above fungus has caused much harm to the
lucerne crops on the Continent, and was identified
by Salmon on lucerne sent to him, which was
ofrown in the Eastern Counties. The funofus
causes wart-like outgrowths at the crown of the
roots, which consist of hypertrophied tissue. In
these swellings there are minute pits in which the
spores of the fungus are found.

Very little is known as yet as to the method of
infection, and in consequence preventive measures
cannot be recommended.

{b) Diseased seeds {^Macivsporium sarcincBforme\
— Fungi Imperfecti ; Order: Moniliales.

This fungus, which has been known for some
time to cause considerable damage to the leaves

DISEASES OF LEGUMINOUS PLANTS 73

and stems of lucerne plants and clover, has been
found inside the seed and causing^ non-cjermination.
Such diseased seed is somewhat shrunk and
wrinkled, and much darker in colour than healthy
seed.

The mode of infection is not known, but in all
probability it spreads from the stem and leaves to
the seed.

PrecmUion. — Buy only seed well harvested in
warm dry districts, and see that it is plump and
bright in colour.

{c) Leaf Spots. — i. Phyllachora Trifolii, Pers. ;
2. Pseudopeziza Trifolii, Fiickel ; 3. Pseudopeziza
medicaginis, Lib.

1. Phyllachora Trifolii. — Causes black shinin*^-
spots on the leaves of clover, especially red clover.
These spots are larger than those caused by
Pseudo. Trifolii. No satisfactory preventive is
known.

2. Pseudopeziza Trifolii. — Causes yellowish -
brown spots on the leaves of clovers, especially red
clover. Serious damage may be caused by this
fundus. Preventive measures of no avail.

3. Pseudopeziza viedicagiuis is res[)onsibl(' tor
the yellow spots on lucerne leaves, and in the
U.S.A. has caused considerable loss. P>ec|U(!nt
cutting has been found to prevent spore formation,
and in this way tends to check the sj)read ol the
disease.

74 FUNGOID DISEASES

Dodder {Cuscuta Trifolit). — This Is a parasitic
flowering plant, iiot a ftmgiis. Its yellowish string-
like stem winds around and entangles the clover
plant and is sometimes mistaken for a fungus. It
is rootless, but is able to obtain a supply of food
through the agency of haustoria (suckers) from the
clover plant, causing as a result reduced growth
of the host and finally death.

Preventive Meastires. —

1. See that samples of clover seed are free from
the seeds of dodder.

2. Dig up attacked patches.

CHAPTER IV.

FUNGOID DISEASES OF POTATOES.

I. Potato Disease {Phytophthora infest ans).
Class : PiivcoiMVCETE/E ; Order : Pekonosporales.

It is also known as potato blight, rot, demic,
etc., all being- names given to the disease caused by
Phytophthora infestans. It was first noticed in the
United States about the year 1840, and in Great
Britain in ICS43. Serious damage was not done

Fig. 21 (A), — Part of a potato leaf with the dark disease spots caused

by PhytophtJioi'n infestans.

until the wet summer of 1845, when practically the
whole area under potatoes suffered.

75

76

FUNGOID DISEASES

Symptoms. — The first sign of the disease Is the
appearance of yellowish-brown thumb-like marks on
the leaves, which, as digestion and decomposition

H

Fig. 21 (B). — Cross-section through a leaf at one of the diseased spots (D) ;
(U) upper and (L) lower side of leaf; (P) palisade tissue ; (S) spongy-
tissue ; (W) the wall of the plant cell ; (H) the hypha of the fungus ;
(Co) the conidiophores ; (C, C, C, C) the conidia.

proceed, become darker In colour (Fig. 21, A).
Around the outer edge of these spots a ring of white
felt-like growth may be seen In very moist weather
on the under side of the leaf (Fig. 21, B).

FUNGOID DISEASES OF FOTATOKS

//

Cause. — Examination of the above felted Lrrowth,
microscopically, shows it to be a plantation-like
growth of the funous PhytophtJiora infest ans, bear-
ing conidia at the tips and sides of the branches
(Fig. 2 1, B). These conidia are easily detached
and carried away by the wind ; if they fall on a
dry surface no further development takes [)lace.
Should they fall on the moist surface of the leaf of

B C D

Fig. 22. — " Potato Disease" [Pliytophthora infcstans) : (A) A conidium
with part of conidiophore (c) attached ; (13) conidium gerniiiiating,
having produced a germ tube [t) ; (C) a sporangium showing the
division into cells; (D) a sporangium germinating, some of the zoo-
spores [z) are already liberated ; notice the cilia or hairs (//) bv means
of which they swim about.

a potato plant, their protoplasm divides, and five to
ten zoospores are formed which subsequently be-
come liberated. Each zoospore consists ot a
minute speck of protoplasm ; bearing two cilia (hairs)
by means of which it is able to swim for a time.
It soon comes to rest, the cilia are resorbed, and
germination commences (see Fig. 22, A, B, C, and
D). The germ tube produced either enters a stoma,
or digests and penetrates the cell wall ot the leat or
stem on which it is found.

7S FUNGOID DISEASES

Once inside the plant, the germ tube branches
and ramifies in all directions, piercing the cell wall
and causing- death of the infected tissues. The
hyphcC in the leaf send out aerial branches through
the stomata bearing conidia (Fig. 21, B), which
become detached, carried in the air to healthy plants,
and hence the rapid spread of the disease, for all
this goes on in the course of a few days. Ulti-
mately the whole haulm succumbs, Phytophthora
being assisted in the later stages of decomposition
by other fungi. Infection of the tubers by the
spread of the fungus down the stem to the tubers
is said not to occur, but takes place, due to the
conidia, or zoospores produced in them, being
washed down through the soil to the young tubers.

The infected tubers may decay at once, or if
the infection is but slight and the soil not too wet,
they may not decay until storage, especially if the
temperature be high and the circulation of air
limited. Such decaying tubers serve as centres of
infection, and the whole of the tubers in the imme-
diate area may become rotten. If stored in a cool
dry place with free circulation of air the slightly
diseased tubers survive, but when planted they
either decay outright, or give rise to short com-
pletely diseased shoots a few inches high, which
bear huge crops of conidia of the fungus in their
short life, and so infect the healthy plants. The
diseased tubers show slightly sunken patches (some-

FUNGOID DISEASES OF POTATOES 79

times called nailheads) varying in size, which when
the epidermis is scraped have a purple colour ; such
a tuber, if cut and placed in a moist warm atmo-
sphere, will develop an abundance of the fungus
hyphae from these spots.

The oospores (resting spores) are claimed by
W. G. Smith to have been found by him in 1875,
but the matter remained in doubt in many quarters.
Recently, however, Dr. G. P. Clinton' at the Con-
necticut Agricultural Station, and others following
his methods, have succeeded in obtaining oogonia
and oospores in pure artificial cultures of the fungus ;
Pethybridge - has shown that they are identical
with the oospores formed by P. erythroseptica,
which causes pink rot of potatoes. It is still un-
certain whether these are ordinarily produced in
nature, but the fact that the disease appears to be
equally as bad (sometimes worse) on newly broken-
up land indicates that the disease is not usually
carried over winter as oospores in the dead leaves,
etc.

Preventive Me as u res. —

1. Plant sound seed.

2. Plant seed of the more resistant varieties.

3. Earth up well so as to prevent the conidia
from beinor washed down to the tubers.

o

1 Clinton, Ti^^/^rA- Coimecticut Exp. Station (191 1), and earlier
reports (1905-10).

2 Pethybridge and Murphy, Sc. Pro. Royal Dublin Society^ Vol.
XIII. (N.S.), No. 36, March, 1913.

8o FUNGOID DISEASES

4. Do not plant too closely, but allow light and
air to enter : crowded plants keep moist longer and
are more likely to suffer from the disease.

5. Spray with Bordeaux Mixture (see p. 25).

6. Collect and burn diseased haulms where this
is practicable.

7. Boil diseased tubers prior to feeding.

8. Cutting off the tops has been found to reduce
the disease in some cases, but results in a decrease
in the crop.

9. Do not dig tubers which are to be stored until
at least ten days after the death of the haulms, so
that tubers already infected may have a chance to
decay, while the danger of infection of the tubers on
diofoinor is to a oreat extent avoided.

II. Potato Leaf Curl [Macrosporium solaui, E.
e t M, ). ^ Fungi Impe j'fecti.

Note. — This disease must not be confused with the " Leaf
Roll " {BlattroUkrankheit) or the " Curly Dwarf" or '' Curly Leaf"
{Kr'iuselh'ankheit) so prevalent on the Continent, which are not
caused by a fungus, l3ut are due to a physiological derangement.

This disease is more prevalent in the United
States (where it is called early blight) and in
Continental Europe than in Great Britain, though
during dry seasons more harm is done to our own
crops than is generally imagined.

Symptoms. — Brown irregular patches, marked by
concentric zones, are found on the leaves, without

' This has been claimed to form its conidia in chains under cultural
conditions and would then be called Altc?'iiaria solani.

FUxNGOID DISEASES OF POTATOES 8i

any visible appearance of the fungus (Fig. 23, A) ;
later, dark patches consisting of masses of conidia
are seen. These conidia are dark coloured, irreuu-
lar in form, and multicellular.

B

Fig. 23. — (A) Potato leaflet sufteringfrom Leaf Curl ; notice the irregular
spots with concentric rings ; (B) club-shaped septate spore of Macro-
sporhim solani with germ tubes from some of the cells; (C) peculiar
forms of spores ; (A) slightly reduced ; (B and C) magnified ; (B and C)
after Jones,

Cause. — The cause of the disease is the presence
of the fungus J/, solani. Its mycelium, which is
dark in colour, destroys the leaf tissue, sometimes
resulting in curling, and forms later, large conidia
on simple, or branched, conidiophores. (Fig- 23,
B and C.)

6

82 FUNGOID DISEASES

Preventive Measures. —

T. Spray early with Bordeaux Mixture (p. 25).

2. Keep the plants in good growing condition by
suitable manurial dressings-

III. Black Leg or Stem Rot [Bacilhtspkyto-
pktkorus^). — Sometimes whole areas (75 per cent of
the crop) become completely rotten, the late applica-
tion of farmyard manure and moist warm weather
favouring the spread of the attack. Cereals have
been proved to be immune.

Sympt07ns. — Seen in June and July, attacked
plants becoming wilted and discoloured from below
upwards, the leaves and the stems below and above
ground being affected. Usually spreads quickly
from one plant to another, and the sets may be-
come rotten. The chief lesions occur in the vicinity
of the ground level, in the form of blackened canker-
like areas, hence the name '' black leg ".

Cause. — Though various fungi are found in the
tissues, the primary cause of the disease is a small
parasitic organism, Bacillus pkytopkthor7ts, which
destroys the living tissues of the plant ; it is un-
doubtedly assisted in the later stages by such fungi
as Botrytis cinerea, Mucor and Fttsaritcni species,
and others.

^This does not belong to the true fungi. A disease is de-
scribed by Harrison, the symptoms of which resemble the above, under
the name of Bacillus solauisaprus (Cent. Blatt f Bact., Bd. 17,
No. 1-2).

FUNGOID DISEASES OF POTATOES 83

Preventive Measures. —

1. Grow cereals on the land for a few years.

2. Apply the farmyard manure in autumn.

3. Avoid forcing artificial manures.

4. Soak the sets in Bordeaux Mixture prior to
planting.

5. Treat the tubers before planting with formal-
dehyde solution (p. 32).

Note. — Not all plants with some of the symptoms described
above are necessarily affected with the disease, as serious local un-
favourable conditions may bring about similar symptoms. However,
if these symptoms show on a number of plants, especially those of a
particular variety or from a special source, care should be taken to
prevent loss by following the preventive measures suggested.

IV. Leaf Roll and Curly Dwarf. — These are
the names given respectively to two diseases of a
serious nature, known in Germany by the names
" Blattrollkrankheit " and " Krauselkrankheit ".
Both are so-called "physiological diseases," not being
caused by parasitic organisms. They are trans-
mitted by planting tubers from plants having the
disease. The disease appears, apparently spontane-
ously, over large areas, affecting certain varieties
and leaving others untouched, possibly climatic con-
ditions are partly responsible.

Syniptovis. — (a) Leaf Roll, The leaves are rolled

upwards on the midrib, and yellowish, or often

reddish or purplish in colour. The plants remain

small and no tubers are formed, or at most only a

cluster of small ones at the base of the stem. Tubers

6 *

84 FUNGOID DISEASES

are often, though not always, produced on the stem
above ground.

[b) Curly Dwa7'f [or O/r/y Leaf). The plants
are dwarfed, particularly the vascular parts, i.e. stems,
branches, petioles, and midrib, and consequently
the leaves are crinkled and curled (downward), the
few tubers produced are small.

Preventive Measures. —

1. Plant tubers only from healthy fields.

2. Practise crop rotation.

3. Keep the ground well cultivated and manured,
and by spraying or other means avoid weakening
of the stock by disease.

V. American Potato Scab [Oospora scabies).
Fungi Imperfecti.

Prevalent on light sandy soils, causing a decrease
in the value of the sample, though they may be of
excellent quality otherwise. Of frequent occurrence
in Continental Europe and in the United States.
There has been much controversy regarding the
cause of this disease, but the conclusions of Thaxter
are now generally accepted for the American scab.

Symptoms. — Instead of the smooth or slightly
roughened surface, attacked potatoes have a very
coarse appearance, being covered externally with
numerous rounded excrescences, caused by the
abnormal production of cork, giving the whole a
reddish-brown, rusty, scabbed appearance.

Cause, — The cause ot the American scab is the

FUNGOID DISKASKS OF I'OTATOFS 85

presence of a minute fungus — Oospora scabies . Ijul
whether this same fundus is the cause of the scab
in Europe is still open to doubt, as owing to the
name scab being assigned indiscriminately to so
many skin diseases a considerable amount of con-
fusion exists.

Lime and alkaline manures are credited with pro-
ducing scab, but while these substances may result
in a form of scab or in an apparent increase of the
attack, the true cause must be looked for in some
parasitic fungus, either similar to, or identical with,
that described by Thaxter.

Whatever the true nature of the disease may be,
the preventive measures recommended by the
American investigators, and enumerated below,
might with advantage be adopted in this country.

Preventive Measures. —

1. Steep tubers to be used for planting in mercuric
chloride solution (p. 31).

2. Plant tubers free from scab.

3. Give infested land a rest from the crop.

4. Do not plant the disinfected tubers in land
where potatoes or beets have developed scab in
previous years.

VI. Wart Disease or Black Scai; {Cliryso-

phlyctis endobiotica) — {SyjichytriuDi endobioticinji.

Percival). Class : Phycomvcete.e ; Order : Chvtri-

DIALES.

This disease is common in Continental Europe,

S6

FUNGOID DISEASES

from whence, In all probability, our land became in-
fected. Schilberszky noted and described it in 1896.
It was noticed in Great Britain In 1899, and is now
very prevalent in Lancashire and the Midlands.

Symptoms, — On certain patches, or In extreme
cases on the whole of the potato, wart-like outgrowths
appear (see Fig. 24, A). As a rule, they are at the
" rose end " only, and are brownish in colour.

B

Fig. 24. — (A) Tubers with warty outgrowths {iv) caused by the wart
disease fungus {Synchitrium cndobioticum) ; (B) two sporangia (rest-
ing stage) with thick walls.

Cause. — The cause of the abnormal growth Is to
be found In a low type of fungus, C cndobiotica, which
gains entrance to the tuber at the " eyes," and once
inside it stimulates the tissues resulting In the wart-
like growths. Numerous swarm spores are pro-
duced in these excrescences, which are capable of

FUNGOID DISEASES OF POTATOES 87

propagating the disease. Under favourable con-
ditions of growth the resting stage (sporangium,
Fig. 24, B) of the fungus is produced, whereby the
winter is brooded over, for apparently there is no
growth in the tuber after lifting.
Preventive Meastires. —

1. Dust the "seed" potatoes with (lowers of
sulphur before planting.

2. Plant sets free from the disease.

3. Grow disease-resistant varieties, e.g. Lang-
worthy.

4. Avoid planting on land where the disease has
occurred.

(See " Highland and Agr. Soc. Journal," 1903,

P- 312.)

Wart Disease is scheduled as a notifiable disease
and must be reported at once to the Secretary,
Board of Agriculture and Fisheries, Whitehall
Place, London, S.W.

VII. Corky Scab or Powdery SQKV>(Spongospoya
subterranea) occurs in the form of powdery ir-
regular patches on the surface of potatoes. It
may be of a serious nature where potatoes are
grown frequently on the same land ; especially
during a wet season. The disease is spread by
planting affected tubers. It has been declared a
notifiable disease, and cases must be reported
without delay to the Secretary, Board of Agricul-
ture and Fisheries, Whitehall Place, London, S.W.

88 FUNGOID DISEASES

VIII. Dry Rot {F2isariuni solani). Fitngi
Imperfecti ; Order : Moniliales.

Some ten to fifteen species of Fttsariuni are
capable of causing rot of potato tubers, some
causing wet, others dry rot. The name Fusarium
solani has probably been applied rather indis-
criminately to all of these. Though the fungus is
widespread, the damage caused is small compared
to that caused by some of the other fungi.

Symptoms. — Shrivelling up of the contents of the
potato, causing cavities on the surface, in which a
whitish grey felted mass of mycelium may be seen.

Cause. — The mycelium noted above is that of
F^csarhcm solani, which grows in and betw^een the
cells, destroying the cell tissue but leaving the starch
grains unattacked, though some of them may, at
the later stages, have the mycelium penetrating
them. Entrance to the potato usually takes place
through some wound, but Wehmer has shown that
the hyphae are also capable of entering potatoes
which are perfectly intact.

The hyphse are long and fine with cross walls.
The spores are very characteristic ; being long,
slender, pointed, cresent shaped, and multicellular.

Note. — Phellomyces sclerotiophorus also causes a dry rot.
Here again the starch grains are very little changed.

Pi'evention. — Unfortunately the fungus is so
widespread that little can be done. The "pies"
may be opened and the diseased tubers picked out.

FUNGOID DISEASES OF TOTAiOFS 89

IX. Wet Rot. — This may cause serious damage
where potatoes are stored in a wet state. Potatoes
grown on wet low-lying land often suffer, and if
Hooded for a few days frequently become reduced
to a mass of pulp.

Sympto77is. — In the "pies" individual potatoes,
or a mass of them, are found with the inner con-
tents a mass of a pulp-like consistency — hence the
name wet rot — and smelling strongly of butyric
acid.

Cmise. — The organisms causing this disease are
not true fungi, two species of bacteria being largely
responsible, viz. Clostridiitni butyricuin and Bacillus
mesenteroides. These multiply in the intercellula)'
spaces, dissolve the cell wall, and in a very short
time reduce the potato to a pulp, the starch grains
remaining intact. The reaction of the inside at
the early stages is acid, but later becomes alkaline.
Clostridium hutyncuni flourishes only without air,
i.e. anaerobic. Kramer isolated an aerobic organism,
i.e. one which grows in the presence ot air, produc-
ing butyric acid and capable of causing wet rot
when inoculated on wounded or unwounded
potatoes,

How far these organisms are assisted in thc:ir
attack by other fungi is not known, but certain it
is that they are not alone in their ravages.

Note. — A species of Rhisocto?iia causes wet rot, and also
attacks the starch grains.

90 FUNGOID DISEASES

Preventive Measures. —

1. Turn potatoes in the "pie" frequently and
remove any rotten tubers.

2. Rotation of crops (doubtful).

3. Drain the land well.

4. Store potatoes in a perfectly dry condition.
Pethybridge (" Pro. Roy. Dub. Soc," Vol. XIII,

No. 35, 191 3, and Vol. XIV, No. 10, 1914) de-
scribes a " wet " rot for which he suggests the name
pink rot and which is caused, by Phytophthora
erytJiJVseptica. Apparently the disease is only of
a serious nature on land that has been successively
cropped with potatoes ; further observations and
inquiries may show that the disease is more wide-
spread and the damage greater than is at present
thouijht to be the case.

X. Spotted Tubers. — Like the markings on the
leaf, those on the tuber are almost legion in
number ; classification is difficult and not very
satisfactory. The exact cause of their appearance
is in many cases obscure.

{a) Blotches or Pimples [Spicaria nivea), — Fungi
Imperfecti ; Order : Moniliales.

Much loss has been caused, especially in Scot-
land and East Anglia, during the past few years,
by a peculiar disease in the form of pimples or
blotches. The author first noticed it on the variety
"Evergood," which is particularly susceptible, but
many or all of the other varieties are attacked. It

FUNGOID DISEASES OF POTATOKS 9!

appears to be worst on land that has been recently
limed.

Syniplo?ns, — The spots may be seen at liftincr
time, but are particularly noticeable after storing.
They occur particularly at the ''rose" end of the
potato and are black or brownish -black in colour,
|- to :f inch diameter, with the circumference sunken
and the centre raised. They penetrate the potato
^ inch only (i.e. skin deep), the inner contents of
the tuber remaining apparently healthy. Not only
are the spots unsightly and reduce the market value ;
but if there are many of them near the " eyes," the
tubers are quite useless as sets.^

Cause. — Microscopic examination of sections
through the spots readily reveals the presence of
fungal threads (Fig. 25, A), and the culture media
inoculated from the inside of the pimples develop,
without exception, a growth of Spicaria iiivca (Fig.
25, B)and sometimes other fungi are present. All
attempts to produce the spots, however, by inocula-
tion of healthy tubers with .V. nivea, or the other fungi,
have failed. Carruthers comes to the conclusion
that the fungi present merely enter the lenticels as
saprophytes, and cause the blackening of the tissue.
The matter is worthy of further investigation.

^The author considers this disease the cause of the great irregu-
larity in many crops of " Evergood," the fungus destroying the eyes.
He saw at one farm in Lincohishire in the spring of 1904 two to four
tons of " deaf sets " which had, fortunately, been noticed and
picked out before planting.

92

FUNGOID DISEASES

Precatitions. —

1. Examine sets carefully prior to planting, and
reject all with blotches.

2. Do not plant potatoes immediately after
limino-.

3. Shun those varieties which are most sus-
ceptible to the attack — *' Evergood," "Flourball,"
etc.

4. Examine " Evergood " seed carefully, and
reject any " blind " sets.

Fig. 25. — {Spicaria nivca) : (A) microscopic section through one of the
pimples on the potato showing the fungus mycelium (;;/) inside the
cells ; (c) the ctll wall ; (/') the remains of digested starch giains ; (B)
portion of the hyphae of Spicaria nivea showing the formation of the
spores in chains. (Highly magnified.)

{/)) Black irregular markings, — Caused by Rhiz-
octonia. Here the skin is perfectly intact and the
blackness can be rubbed or washed off.

[c) Some scu7'f diseases, not of a serious nature,
are said to be due to mechanical disturbances.

(rtf) The lenticels are often seen in the form of small

FUNGOID DISEASES OF FOTATOES 93

raised meal-like markings, and are sometimes mis-
taken for disease spots. The potatoes are, however,
perfectly healthy.

{e) Rttst'like specks or streaks are sometimes found
inside otherwise sound tubers, hence the names
*' streak," ''sprain". The cause is not definitely
known. No fungus has as yet been found within ; it
does not spread in the "pies," and is apparently
not contagious. Weather and soil conditions are
thought to be responsible, but further research may
reveal the presence of some organism within the
tissues.

Note. — For insect pests attacking this group see " Farm and
Garden Insect Pests," by Somerville. M.M. & Co.

CHAPTER V.

FUNGOID DISEASES OF CRUCIFERS.

I. Finger- AN D-ToE iyPlasinodiophora brassicce).
Class: MvxoMVCETES (Slime Fungi).

This disease is also known as anbury and club
root. It is widespread, and attacks many kinds of
cultivated and wild crucifers, but cabbages and
turnips in particular.

Symptoms. — Abnormal tuberous swellings ^ (see
Fig. 26) appear of no fixed form, which gradually
become rotten and give off a very disagreeable
smell. While this is going on, the leaves lose their
waxy bloom and healthy green appearance, turning
yellow and stunted in growth. Finally the whole
root and leaves may become one mass of putre-
faction.

Cause.- — Woronin first found the slime funofus
Plasmodiophora hrassicce which causes this disease.
Sections through the swollen parts, examined
microscopically, show that certain of the cells are

1 Not to be confused with the swellings caused by the turnip
gall wee\'il {Ceutof'hy?ichus stilcicollis).

94

FUNGOID DISEASES OF CRUCIFERS 95

abnormally enlarged and filled with a slimy sub-
stance which is the protoplasm of the fungus.
After feeding in the
cell lor a time, this
foreign protoplasm
(plasmodium) breaks
up and forms numer-
ous spores within, and
filling up, the enlarged
cells (see Fig, 27).
These spores are liber-
ated in millions in the
decaying mass.

Under favourable
conditions the cell wall
of the spore ruptures
and a small mass of
protoplasm is liberated
bearing a cilium (hair-
like growth) by means
of which it is able to
move about. Shortly
this is resorbed and
subsequent movement
takes place in a creep-
ing manner, i.e. by the
small portion of proto-
plasm changing its shape. In this stage it is able
to enter a cruciferous plant, exactly how and where

Fig. 26. — Turnip showing the peculiar
finger-and-toe-like swellings on the
roots caused by Plastnodiophora
brassicci ; the upper swellings are
in an advanced state of decay.
(After Northumberland C.C.)

96

FUNGOID DISEASES

is not known, but probably via the root hairs. Once
inside, food is absorbed from the cell contents, ir-
ritation is set up, and the abnormal cells result in

\1

Fig, 27. — Finger-and-Toe Disease (Plasmodiophora brassicce). Showing
giant cells in portions of tissue taken from the abnormal growths on
roots ; note that the protoplasm of the fungus has broken up into a
mass of spores ; (a) spores more highly magnified ; (b) " germina-
tion " of spores ; (c) the ciliated portion of naked protoplasm emerging ;
(d) the naked protoplasm (plasmodium) liberated. (After Woronin.)

consequence. Portions of protoplasm are capable
of piercing the cell wall and entering previously
healthy cells.

How long the spores retain their power of ger-
mination, how winter is passed, and how the small

FUNGOID DISEASES OF CRUCJFERS 97

protoplasmic mass enters the plant, are points await-
ing solution.

Pi^eventive Me as it res, —

1. Do not grow cruciferous plants too often on
the same land.

2. Remove diseased roots from the field.

3. Do not spread refuse from the turnip heaps
on land where turnips, etc., are to be grown.

4. Disease is most prevalent on sour land ;
sweeten such land by drainage, and by the applica-
tion of about 2 tons or more of lime per acre,
immediately the turnip crop is removed, and in
extra quantities where the disease was worst. Gas
lime is of little value for the purpose.

5. Keep down cruciferous weeds — charlock,
shepherd's purse, etc.

6. Avoid the use of acid manures, e.g. super-
phosphate.

7. Prevent as far as possible the transportation
of soil from infected to healthy areas.

8. Do not raise seedlings for trans[)lanting on
land that is susceptible to the disease.

9. Do not plant clubbed seedlings.

II. Damping Off [Pythiuvi dc Baryaumu).
Class : PiivcoMVCETE/K ; Order : Saprolf(;niales.

A troublesome disease to the gardener, most

cruciferous plants being affected, but especially

mustard and cress. It is not confined to crucifers

only.

7

98

FUNGOID DISEASES

Symptoms. — Where seedlings are too thick and
too moist, they turn yellow in patches ; and, due to
a weakened place in the stem, at the soil level, fall
over ; the attack spreading with amazing rapidity.

Cause. — Indirectly the cause is too thick seeding
and too much moisture ; directly the fungus Pythium
de Baryanum is the culprit. Its branched non-
septate hyphae grow within the plant and draw

Fig. 28. — Pythium de Baryanum: (i) Portion of mycelium bearing
conidia (C) at the ends of the branches ; (2) Sporangium with zoo-
spores enclosed (Z), a zoospore with a cilium or hair ; (3) Antheridium
and Oogonium ; after uniting a resting spore, called an oospore, is
formed. (After De Bary.)

nourishment from the contents of the cells; result-
ing in the weakening of the part and consequent
falling over. Later the hyphse grow on the out-
side and may reach short distances to healthy
plants.

Preventive Measures. —

1. Do not sow too thickly.

2. Do not shade seedlings too much or keep them
too moist.

FUNGOID DISEASES OF CRUCIFERS 99

3. Do not grow seedlings on infected soil, but
regulate the moisture in the soil and air so as to
have an optimum for plant growth without an excess
which favours fungoid growth.

4. On first appearance remove diseased patch
and a coronet of the surrounding healthy plants, and
burn.

5. Deep cultivation has been recommended, as
it is said to bury the oospores.

6. Steeping the seed in various solutions has
been suggested, but seeing that the fungus is
capable of living as a saprophyte in the soil it is
difficult to see how this can be of any use.

7. Spraying the surface of the soil with Bor-
deaux Mixture will sometimes prevent the spread
of the disease in the seed bed.

III. Mildews.—

(a) True Mildew [Ii7'ysip/ie Martii). Class :
AscoMVCETE.E ; Order : Perisporiales.

(K) False Mildew i^Peronospora parasitica).
Class : Phycomvcete.e ; Order : Peronos mor-
ales.

{a) True Mildew. — A species of Erysiphc identi-
cal with E. Martii is found on the surface of cruci-
ferous plants— for description see under clover
mildew, page 63.

(b) Praise Mildew [Perotiospora parasitica). — •
Various cruciferous plants are susceptible, but prob-
ably swedes suffer most, especially in dry seasons,

100

FUNGOID DISEASES

and with early sowing. It often occurs in company
with white rust.

Symptoms. — i\ grey white mould appears on the
under side of the leaves ; the latter assume at the
same time a sickly appearance, shrivel up, and
when rain comes, rot with a strong characteristic
odour.

Cattse. — Peronospora pm^asitica causes this dis-
ease. Its hyphse grow within the plant (compare

true mildews) and draw nour-
ishment from the cell contents,
thereby preventing normal
development. Aerial hyphse
are sent out through the
stomata, which branch in a
tree-like manner, and form,
at the tips, colourless con-
idia (Fig. 29) which fall off
easily and are capable of im-
mediate ofermination. Rest-
ing spores (oospores) with a
thin yellowish outer wall are
formed, on the mycelium
within the plant, as a result of sexual union. These
develop the following spring.

Preventive Measures. — On account of the wide-
spread nature of the fungus, little can be done.

1. Keep down all cruciferous weeds.

2. Sow swedes later in the dry warm districts,

Fig. 29. — Conidiophore of
Pcronospora parasitica,
which causes fa se mildew
of swedes, growing
through a breathing pore ;
notice the detached con-
idia. (Magnified. ) (After
Frank.)

FUNGOID DISEASES OK CRL-ClKKKS loi

3. Apply nitrate of soda, as a top-dressing.

4. Frequent horse-hoeing even in the late sum-
mer has in many cases been found beneficial.

IV. White Rust {Albugo Candida. Kuntz. ; ( 'v-
stopus candidiis, Pers.). Class : Phvcomncktk.i-: ;
Order : Pkronosporalks.

This fungus attacks various cruciferous plants,
but is especially abundant on shepherd's purs(;
{Capsella bursa pastoris) where it appears as a
lime-white coverino" causino^ deformitv of the stems,
leaves, and leaf-stalks.

The mycelium grows within the host ; later it
bursts through the surface,
forming spores (in chains)
(Fig. 30) which constitute the
white powder. These spores
are carried by the wind, and
in the presence of moisture
give rise to zoospores which
swim for a time, and on
coming to rest, form a germ
tube which can enter a cru-
ciferous plant. Resting
spores are formed as a re-
sult of sexual union, in most plants, but not in
shepherd's purse.

V. Blackening of Rape. — Rape in particular
suffers from the attack of Sporidesniiuui cxdiosuui,
which forms blackish-brown spots, especially on the

Fig. 30. — White rust {Cysto-
piis candidits). Portion of
the hypha with conidio-
phores ; (</) bearing the
con i d i a (i ) in chains.
(Magnified.)

102 FUNGOID DISEASES

"seed pods/' but also on the stem. The pod
shrivels and seed formation Is prevented.

On account of the wide distribution of the fungus
little can be done to prevent It.

\T. ScLEROTiUM \}i%Y.k^Y.{Sclerotinia libertiana ;
Sclerotinia s clerotiorimi , Massee). Class : As-
COMVCETES ; Order : Pezizales.

* Rape, swedes, and turnips are attacked In parti-
cular. The mycelium Is only able to enter the
host after being nourished for a time saprophytl-
cally. A description of this fungus Is given on
page 6^, under sclerotlum disease of clover.

Since the sclerotia are capable of resting for a
long time, and the fungus Is able to grow as a
saprophyte, little can be done to prevent attack.
Liming Is to be recommended.

Note. — For insect pests of this group see " Farm and Garden
Insect Pests," by Somerville. M.M. & Co.

CHAPTER VI.

FUNGOID DISEASES OF MANGELS AND ru:ET.

I. False Mildew {Pejvnospora schaclitii).
Class: PiivcoMVCETE.E ; Order: Peronosporales.

Both mangels and beet are attacked, the latter
to a serious extent in France and Germany.

Syniptorus. — In May and June the young leaves
assume a light green colour, and become crumpled
in a bladder-like form with the outside edges
turned under. A grey coverino- of mycelium is
found on the under side. Plants attacked are
dwarfed in growth, or may be altogether destroyed.
Single plants or patches suffer.

Cause. — The greyish patches on the under side
of the leaf consist of conidiophores of the fungus
Peronospora schaclitii which causes the disease.
The conidiophores grow through the stomata and
bear at the tips oval-shaped spores that are easily
detached and carried by the wind. They
germinate readily on a moist surface, and if ger-
mination takes place on beet or mangel leaves the
germ tube enters and grows within. Resting spores,

with thick walls, are formed within the dead leaves,

103

104 FUNGOID DISEASES

and the mycelium remains over the winter in the
roots.

Precautions. —

1. Remove all diseased plants.

2. Grow some other crop for a year or two.

3. Keep down weeds.

II. Leaf Spot {Cercospora beticola). Fungi
Imperfecti ; Order : Moniliales.

Both mano^els and sug^ar beet are attacked.

Symptoms. — Very small grey round spots, with
a dark red circumference, appear on the leaf in
summer, consisting of conidiophores bearing long,
tail-like, colourless conidia with cross walls. With a
few spots only, no serious damage results ; if an
abundance the plant suffers.

Cause. — The fungus Cercosp07'a beticola causes
the disease. The long septate conidia are carried
by the wind on to healthy leaves, where they
germinate. Growth is limited in area, each spot
being the result of a separate infection. Winter
spores are not known.

The damage caused is not as a rule serious, and
no satisfactory preventive can be given ; burn the
leaves after harvesting, if the disease is abundant.

III. Leaf Brown {Sporidesmium putr'efaciens,
Fuckel). Fungi Imperfecti ; Order : Moniliales.

Both mangels and sug^ar beet suffer.
Sympto77is. — Appears in late summer and
autumn ; the oldest leaves are attacked, the

, DISKASES OF MAXGKLS AND BEET 105

\

youno-est being- free. Differs from leaf spot in
that the whole leaf surface turns brown, and
thickens.

Cause, — Investigation has shown that on and
within the surface of the brown parts the mycelium
of .V. putrefaciens may be formed. Trom this
mycelium brown hypha- arise, bearing- at the ends
large pear-shaped septate spores, which are very
easily detached and carried by the wind. A germ
tube grows from each of the chambers.

Pi'eventive Measures. —

1. Remove the leaves of attacked crops.

2. .Steep the seed in formaldehyde solution (see

p. 32)-

i\^ Leaf Rust i^Uromyces Bctcr, Tulasne).

Class: Teliosporpie ; Order: Ureimnales.

This disease is seen on both mangels and sugar
beet, especially in those fields where they are grown
many years in succession. Damage is not serious.

Symptoms. — Appears on leaves late in the season
in the form of small yellow^ish pustules, the re-
mainder of the leaf remaining a healthy green, unless
the spots are exceedingly numerous, in which case
it turns a sickly colour. It is chiefly the older leaves
that are attacked.

Canse^ — ^The disease is due to Uromyces BetcF.
The pustules on the leaf consist of uredospores of
the fungus ; these are blown to healthy plants, there
setting up new centres of disease.

io6 FUNGOID DISEASES

Preventive Measures. —

1 . Remove all tops and refuse.

2. Grow mano^els on other P^round.

3. Spraying with Bordeaux Mixture is recom-
mended, but it is of doubtful value.

V. Beetroot and Mangel Rot [^Phonia Betce,
Frank). Fungi Iniperfecti ; Order: Sph.^ropsi-

DALES.

Symptoms. — Seen in dry summers during July
and August and sometimes later. The young inner
leaves become blackened ; in bad cases the whole
of the leaves suffer, the attack spreading from the
inner leaves outward. Later the mano^el itself falls
a prey to the fungus (this constitutes the dry rot) ;
first the epidermis is discoloured, and later the inner
tissue becomes brown and dry.

Cause. — The fungus Phoma BetcB with its thickish,
septate, colourless hyphae is present in the tissues
causing disease, Picnidia (small cases containing
spores) are seen in the diseased tissue as minute black
points. They liberate the spores from a small
opening. They may remain in the ground a long
time and still be capable of germination when
favourable conditions occur.

This fungus is often accompanied by Fusarium
beticola, which has crescent shaped spores.

VI. Violet Root Rot {Rkizocto7iia vio/acea).
Fjingi Imperfecti.

Mangels and beet suffer, though not seriously.

DISEASES OF MANGELS AND BEKT 107

A purple red covering of mycelium is found on the
root, causing rotting. No spores are formed. For
description of the fungus, see p. 71.

Attack is said to be worst on badly drained land.

VII. Beetroot and Mangel Tumour [Oedomyces
leproides, see note on p. 108). Sub-Class : Phy-
COMYCETE/E ; Order : Chytridiales.

"^^^£^^-5*^^

Fig. 31. — A mangel showing the large tumour on the left side.

{a) Beetroot. — This disease was found near Al-
giers, and described by Trabut. Large brain-like
swellings or fleshy tumours are found above the
ground, and are attached to the root by a very
narrow neck. Spores are found in small cavities
in the tumours.

(^) Mangel. — The author found a similar disease
to the above on mangels grown on land heavily

lo8 FUNGOID DISEASES

dressed with ofas lime. The swellinofs were at
the soil level, some of them being- bigger than the
double hand (see Fig. 31). No fungus mycelium
nor spores could be detected within the hyper-
trophied tissue, but it is conceivable that the fungus
found on the beet is also the cause of the mano-el
tumour. Observation leads him to believe that the
parasite enters at the small pits made in the root at
the soil level by slug bites, etc. ; there is, however,
no direct proof of this.

Note. — Professor Bessey suggests that the tumours may have
been caused by the crown-gall bacteria {^Pscudomoiias tiiinefacicns)
which is known to cause large galls on mangels and other plants.

APPENDIX.

FUNGOID DISEASES OF ANIMALS.

Here again only those diseases caused by the
true fungi will be described ; the reader being re-
ferred to books on animal pathology for descrip-
tions of the innumerable diseases caused by bacteria.

I. Wooden Tongue [Actinomyces bovis). — Also
known as actinomycosis, lumpy jaw, cancer of the
tongue, etc. It appears most frequently in the
ox, but pigs and human beings are sometimes at-
tacked. In the ox the tongue is the chief seat of
disease, but in castrated animals the spermatic
cord may become infected ; it has also been found
in the peritoneum.

Symptoms. — On and within the tongue small
flattened, greyish -yellow or reddish nodules or ab-
scesses appear \ to i inch in diameter, microscopic
examination revealing the presence of a fungus.
These nodules harden and sometimes lime is de-
posited, giving a granular appearance. The animal,
rolls its tongue about, and swallows with difficulty ;
saliva drops from the mouth, and the tongue is
swollen and hardened. The disease may spread
from the tongue to the lower jaw.

jog

no FUNGOID DISEASES

Cause. — The abnormal appearance above noted
is caused by the parasitic fungus Actinomyces bovis^
which was first discovered by Bollinger about 1877.
Sections through the nodules show that they con-
sist, internally, of loosely arranged knot-like
branched hyphae, which are arranged radially at the
periphery of the nodule (hence the term ray fungus),
and terminate in a flask-like expansion. Numerous
small bodies resembling cocci or bacilli may be
found arranged end to end in the sw^ellings, and
also liberated and distributed between the hyphae ;
they result from the breaking up of the hyphae and
are called " fragmentation spores ".

Most authorities now consider the disease of
bacterial origin.

Ti'eatment. — The disease is most difficult to
combat. Pricking the tongue with a needle has
been recommended, but is of doubtful value. Some
veterinary surgeons advise immediate slaughter ;;
in any case, professional advice should be sought.

Scrape the parts and dress with a solution consist-
ing of equal parts of tincture of iodine and carbolic
acid, and give iodide of potash internally ( Levie).

II. Ringworm (Oidiwn tonsurans; Trichophy-
ton tonsiwans, Malmsten ; Herpes tonstcrans).
Fungi Imperfect i.

Most frequent on young cattle in poor condi-
tion, but also found on horses, goats, and dogs.

Symptoms. — Irregular circular areas appear,

FUNGOID DISEASES OF ANIMALS iii

especially about the face and neck, devoid of hair
and varying in size from a fraction of an inch to
several inches in diameter. The skin on these bare
surfaces is wrinkled, encrusted, and scabbed in ap-
pearance. In the earlier stages small bladders are
seen from which an evil-smelling substance exudes.
These dry up, forming the bark or crust of greyish-
brown leathery scales mentioned above.

Cause. — The bladder-like swellings and loss of
hair are caused by the parasitic fungus Oidiuin ton-
surans, of which there appear to be several varieties.
It grows readily on blood serum, where it forms, on
the hyphse, chains of roundish oval conidia, w^hich
spread the disease. Whether this fungus is identi-
cal with the one found on human beings is still an
open question.

Remedial Afeasures. — Clean the parts well by
scraping and brushing and afterwards apply one of
the following dressings, which must be repeated
should occasion require : —

[a) Train oil 5 parts, sulphur i part.

i^b) Soft soap 5 parts, sulphur i part.
. [c) Olive oil 8 parts, creosotell i part.

Levie recommends the following : wash well with
warm water, washing soda, and soft soap, rub off
the crusts with emery paper, and next day when dry
paint the parts with the following: —

I oz. Sir Wm. Burnett's disinfecting fluid, 24
oz. water (shake well before using).

112 FUNGOID DISEASES

III. Favus in Poultry i^Achorion Schonkinii,
Remak) [Oidliun Schonleinii, Grawitz), Fungi
Iviperfecti.

Almost all breeds of poultry are attacked, the
disease being very contagious, a single case soon
contaminating the whole run. The disease is also
common in children.

Symptoms. — Small, pale, irregular, shield-like pits
appear on the comb ; and later on the wattles and
head. They coalesce, thicken, and become'yellowish-
grey. The feathery parts, especially the breast and
neck, may be attacked, the feathers drying up and
falling off. The disease is most difficult to combat
at this stage, often ending fatally.

Cause. — Oidium Schonleinii, or a parasitic fun-
gus closely resembling it, causes the above disease,
gaining entrance to the comb probably at some
abrasion and spreading to the wattles, neck, and
breast. Grown on artificial media, the mycelium
is greyish white ; from it spring soft white fluffy
aerial hyphse, bearing the conidia in chains. They
may be produced in such profusion, both here and
on the comb, as to form a dust-like covering over
the whole surface. The fungus also possesses the
following characteristics : is sensitive to acid in the
medium, forms a sulphur yellow colouring matter,
likes fairly high temperatures, and produces an
alkaline by-product.

Remedial Measures. — Always isolate and treat

FUNGOID DISEASES OF ANIMALS 113

immediately when seen. Clean the affected parts
either by washing- well with solt soap and water,
or rubbing with emery paper and brushing, and
apply any of the following : —

(a) Sulphur ointment.

(d) Paint with iodine solutions.

(r) 5 per cent silver nitrate in lard.

(d) 10 per cent solution of carbolic acid,

(e) Mercuric oxide i part, lard 8 parts.

Note. — for insect pests, see "Farm and Garden Insect Pests,"
by Somerville. M.M. (fc Co.

8

INDEX.

Abnormal flowering, 15.

— fruit, 14.

Achorion Schonleinii, 112.

Actinomyces bovis, 109.

Actinomycosis, log.

Adaptability, 22.

Aecidiospores, 11, 16, 51, 55.

Aerobic, 8g,

Albugo Candida, loi.

Algae, 38.

Alopecurns pratensis, 57.

Anaerobic, 89.

Anbury, 94.

Animals, diseases ot, 109-13.

Anthracnose, 70.

Ascochyta pisi, 6g.

Asco7nycetea, 35. 3^, 38, 55.

67, 99, 102.
Ascospores, 7, 56.
Ascus, 35, 56.

Bacillus viesenteroides, 89.

— phytophthonis, 82.

— solanisaprus, 82.
Bacteria, i, 89.

Bad nourishment, 22.
Barley, blackened, 61.

— covered smut of, 42.

— deaf ears of, 60.

— leaf brown of, 60.

— naked smut of, 42.

— rust, 53.

Basidioviycetece, 35, 38,
Beans, diseases of, 63, 74.
Beetroot, diseases of, 94-102.
Berberis vulgaris, 11, 50, 51.
Black leg, 82.

— scab, 85.
BlattroUkrankheit, 83.
Board of agriculture, 87.

Bordeaux mixture, 25.
Botrytis cinera, 82.
Brome smut, 44.
Brotnus mollis, 44.
Brown rust, 52.
Buckthorn, 54.
Budding, 9, 41.
Bugloss, 53.
Bunt, 9, 29, 33, 45.

Campion, 15.
Cancer of the tongue, 109.
Capsclla bursa pastoris, 15, lOi.
Carpomycetea', 34.
Cercospora beticola, 104.
Cereals, diseases of, 39, 62.
58, 63, j Ceutorhynciis sulcicollis, 94.
Chlamydospores, 7, 40.
Chlorophyccce, 35.
Chlorophyll, 2.

Chrysophlyctis cndobiotica, 85.
Chylridialcs, 85, 107.
Cilia, 77, 96, 98.
CladocliytridiacciV, 72.
Cladosporium hcrbarum, 6r.
Clavii.eps purpurea, 7, 55.
Clostridium butyricum, 89.
Clovers, diseases of, 63, 74.
Club root, 94.
Cocksfoot, 54j 57.

Colletotrichutn lindi'muthianum, 70.
Conidia, 7, 41, 65, 76, loi.
Conidiophore, 4, 76.
Continued cropping, 22.
Contortions, 15.
Copper sulphate solution, 28.
Corky scab, 87.

Corrosive sublimate solution, 31.
Crowded cropping, 21.
Crown gall of clover, 72.

115 ^

ii6

FUNGOID DISEASES

Crown rust, 53.

Cruciferous plants, diseases of, 94-

102.
Curly dwarf, 80, 84.

— leaf, 80, 84.
Cuscnta Trifolii, 74,

Dactvlis glonierata, 54, 57.
Damage done by fungi, 23.
Damping off, 97.
Discoloration, 15, 17, 59.
Disease, conditions favourable, 20.
unfavourable, 23.

— diagnosis of, 17.

— signs of, 16.

— spread of, 18.
Dodder, 74.
Drop cultures, 8,
Dry rot, 106.

of potatoes, 88.

Effect of parasite, 13.
Endophytic, 13.
Endospores, 7.
Entomophthorales, 35.
Epic hi oe typhina, 57.
Ep'idermis, 20.
Epiphytic, 13.
Ergot, 55.
Erysiphe, 5, 12, 13, 65, 66.

— gramiiiis, 58, 64.

— Mar Hi, 63, 99.
Euphorbia, 67.
Evergood, 90, 92.
Exoascus priini, 14.

Favus in poultry, 112.
Ferrocyanide test, 27.
FesUica silvatica, 54.
Finger-and-toe, 19, 21, 94.
Flourball, 92.

Formaldehyde solutions, 32.
Fungi, I.

— classification of, 34.

— damage done by, 23.

— how plant is entered by, 19,
Fungi imperfecti, 36, 38, 61, 62,

69-72, 80, 84, 88, 90, 104, 106,

110-12.
Fungicides, 24.
Fiisarium solani, 7, 88.

— species, 15, 82, 88.

Germ tube, 19.

Germination of spores, 710, 47, 77.

Golden rust, 52.

Grass, black spots on, 62.

— diseases of, 39.

Haustoria, 5.
Heltninthosporiuni graminciim, 60.

— teres, 62.
Higher lungi, 34.
Host, diversity in, 22.

— influence of, 15.

Hot water treatment, 29.
Hyphae, 2, 3.

Infected tubers, 78.

Krauselkrankheit, 'io, 83.

Langworthy, 87.
Lathyrus, 63, 67.
Leaf, brown, 104.

— curl, 80.

— roll, 83.

— rust, 105.

— spots, 62, 73, 104.
Leguminous plants, diseases of, 63,

74:
Lenticels, 92.

Leptosphcsria Tritici, 60.

Lime sulphur, 33.

Litmus paper, 27.

Liver of sulphur, 31.

Loose smut of barley, 42.

of wheat, 43.

Lower fungi, 35.

Lucerne, diseases of, 67, 71, 72.

Lumpy jaw, 109.

Lychnis dioica, 15.

Macrosporium sarcinaforme, 72.

— solani, 80.
Maize, smut of, 44.
Mangels, diseases of, 103-8.
Meadow foxtail, 57.

Mildew, 3, 12, 13, 49, 63-66, 99,
103.

— downy, 66.

— false, 64, 99.
Moniliales, 61, 72, 88, 90, 104.
Mucor mucedo, 4, 7, 13, 82.
Mucorales, 35.

INDEX

117

Mycelium, 2, 3.
Myxomycetes, g\.

Nourishment, inriuence of, 22.

Oats, leaf brown of, 62.

— smut of, 39.
Oidium lactis, 7.

— schonleinii, 112.

— tonsurans, no.
Oogonia, 79.
Oospora scabies, 84.
Oospores, 7, 78.

Parasites, 2, 12, 64.
Peas, diseases of, 63-74.
Penicilliiim glaiicwn, 7, 13.
Perisporiales, 58, 64, 99, loi, 103.
Perithecia, 56.
Peronospora parasitica, 99.

— schachtii, 103.
— ■ Trifoliormn, 64.

— vicice, 64.

Peronosporales, 35, 63, 66, 75, 99-

loi, 103.
Pezizales, 67, 68, 102.
Phellomyces sclcrotiopJiorus, 88.
Phoma beta:, io5.
Phycomycetece, 34, 35, 38, 64, 66,

72, 75. 85, 97, 103, 107.
Phyla, 34.
Phyllachora graminis, 62.

— Trifolii, 73.

Physiological derangement, 80, 83.
Phytophthora erythroseptica,'jq, 90.

— infestans, 12, 13, 16, 18-21, 66,

75-80

— Phaseoli, 66.
Picnospores, 11.
Pisum, 63, 67.
Plasmodiophora brassicce, 20, 22,

94.
Plasmodium, 95.
Pocket plums, 14.
Poly poms, 13, 20.
Potato, diseases of, 75-93.
Powdery scab, 87.
Premature buds, 15.
Preparation of fungicides, 26.
Promycelium, 41, 47.
ProtococcoidecB, 35.
Protoplasm, 2, 95.

Pseudomonas Itimefaciens, 108.
Pseudopeziza inedicaginis, 73.

— Trifolii, 73.
Puccinia coronuta, 53,

— coro)iifera, 54.

— dispersa, 52.

— glnmarnm, 52, 53.

— graminis, 5, 10, 14, 16, 49, 67.

— rubigo vera, 52.

— simplex, 53.

— straminis, 52.
j Pustule, 50, 52.

Pyrenoinycetalcs, 55, 57.
Pythinni de Baryaniim, 97.

Ray fungus, no.

Reproduction, 10.

Rhizoctonia violacca, 15, 71, 106.

RhodophycecB, 35.

Ringworm, no.

Root hairs, 14, 20, 96.

Rust, 10, 12, 14, 48, 66.

Rust-free wheat, 48.

Rye, ergot of, 55.

— smut of, 43.

Saprolegmiales, 35, 97.
Saprophytes, 2, 6, 12.
I Scab of potatoes, 84, 85.
Sclerotia, 4, 57, 67, 68.
Sclerotinia libertiana, 102.

— sclcrotiornm, 19, 102.

— Trifolioritm, 67.
Sclerotium disease of clover, 67.
Sep tor ia avcnce, 60.

— briosiana, 60.

— glnmarnm, 60.

— graminenm, 60.
Sheep's fescue, 54.
Shepherd's purse, 15.
Siphonophycecc, 34.
Slime fungi, 95.
Smother fungus, 57.

Smut, 9, 12, 15, 29, 32, 39-4''^-
Soda Bordeaux, 28.
Soft brome, 45.
Sphc€rella exitialis, 60.
Sphcrropsidalcs, 69, 106.
Spicaria nivca, gj.
Sporangiophore, 4.
Spores, 4, 7, 47.

— distribution of, 7, 18, 23.

Ii8

FUNGOID DISEASES

Spores, germination of, 7.
Sporidesminm exitiosum, loi.
— putrefaciens, 104.
Spot disease of peas, 6g.

of potatoes, go.

Sprain, 93.

Spring rust, 52.

Spurge, 67.

Stem rot of potatoes, 82.

Stinking smut, 43, 45.

Straw, blackening of, 61.

Streak, 93.

Stroma, 56.

Sulphur, 34.

SynchytriacecB, 35.

Synchytrium endohioticum, 85.

Tall oat grass, smut of, 45.
Teleutospores, 11, 16, 50.
Teliosporecz, 34, 36, 38, 39, 45,

66, 105.
Teliospores, 40, 50.
Tests for Bordeaux mixture, 27.
Tilletia, 9, 41, 45.
TilletiacecF, 36, 45.
Trichophyton tonsurans, no.
Trimethylamine, 46.

Uredinales, 12, 36, 48, 66, 105.
Uredospores, 11, 16, 50, 54.
Urocystis Agropyri, 44.

— occulta, 43.
Uromyces apiculatiis, 67.

— BetcE, 105.

— phaseolorum, 67.

Uromyces pisi, 67.

— striatus, 67.

— Trifolii, 67.
Urophlyctis alfalfce, 72.
Ustilago, 9, 15, 39.

— avencE, 39.

— bromivora, 44.

— hordei, 42.

— yensenii, 42.

— IcEvis, 39.

— Maydis, 44.

— Hilda, 42.

— perennans, 45.

— Secalis, 44.

— Triiici, 43.
Ustilaginales, 36, 39-45.

Vegetable kingdom, 37.
Vicia, 63-66.
48, Violet root rot, 71, 106.

Wart disease, 85.
Weather, influence of, 20.
Wet rot, 89.
Wheat, browning of, 59.

— bunt, 45.

— mildew of, 58.

— rust of, 49.

— smut of, 41, 43.
White rust, 15, 16, loi.
Witches' broom, 15.
W^ooden tongue, log.

Zoospores, 20, 77, 98.
Zygospores, 7.

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