The diseases of crops and their remedies : a handbook of economic biology for farmers and students

| ‘Bell's Agricultural Series

_ DISEASES or CROPS
: AND THEIR

REVEDIES

_ DR A. B.GRIFFITHS

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Bell’s Agricultural Series.

THE DISEASES OF CROPS.

__—

A. B. GRIFFITHS.

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THE

DISEASES OF CROPS

AND

THEIR REMEDIES:

A HANDBOOK
OF ECONOMIC BIOLOGY FOR FARMERS AND STUDENTS.

BY

A. B. GRIFFITHS, Pu.D., F.R.S.E., F.C.S.,

Late Principal of and Lecturer on Chemistry and Biology, the School of
Science, Lincoln; Lecturer on Chemistry, Lincoln Gr
School; Formerly Director of the Chemical Laboratories,
Manchester Technical School; Member of the Chemical
Societies of Paris and St. Petersburg; Author of
‘*A Treatise on Manures,” ‘‘ Manwres and their
Uses,” etc., etc.

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1890.

TO
A. C. MAYBURY, ESQ., D.Sc. (Lond.), M.R.CS., F.G.S.,

ASSOCIATE OF THR ROYAL SCHOOL OF MINES;
AUTHOR OF “TH STUDENT'S CHEMISTRY,’ AND TRANSLATOR OF
*OVID'S METAMORPHOSES,” “ TRISTIA,” BTC.,
(WHOSE MASTERLY AND ELOQUENT DISCOURSES, GIFTED TALENTS,

AND VARIED ACCOMPLISHMENTS ARK WELL KNOWN TO MANY FRIENDS
AND SIfUDENTS OF SCIENCE, MEDICINE, AND LITERATURE)

THIS WORK IS AFFECTIONATELY DEDICATED

BY HIS SINCERE FRIEND,

THE AUTHOR.

PREFACE.

As economic biology and pathology are subjects worthy
of the deepest study on the part of farmers, market-gar-
deners, and others interested in the cultivation of crops,—
my aim has been to make this little volume a useful
companion to those who are interested in the diseases of
crops caused by the attacks of parasitic insects and fungi.

The annual loss from the ravages of insects and fungi
upon growing crops is beyond calculation ; but it may be
estimated that on the average at least “ one-sixth” of the
entire yield of farm-crops, hop-gardens, etc., is sacrificed
through the ravages of insect and fungoid pests.

“As actual instances of the enormous losses which
farmers sustain through the ravages of insects, it may be
mentioned that Miss Ormerod estimated, for the season of
1881 alone, the financial loss represented by the cost of
seed and the expenses of sowing and re-sowing the turnip
crop destroyed by the ‘turnip-fly’ in twenty-two English
and eleven Scotch counties, amounted to over half a
million pounds sterling.” In Mr. Whitehead’s Official
Reports for 1886 and 1887 it is stated, “ that the ‘diamond-
back turnip moth’ is the cause of losses estimated at
from £4 to £6 per acre; that the ‘dart moth’ occasioned
to a market-gardener in Essex losses to the extent of more
than £100; that through the ‘ mangel-wurzel fly ’ farmers

Vv

vi PREFACE.

in Derbyshire and Hampshire had both lost over £100 in.
one season on this crop alone; and that the losses to hop-
growers due to the hop aphis have been incalculable.
In the last serious blight in 1882, the whole produce of
the hop lands in England—65,619 acres—did not exceed
114,832 cwts., or a yield of 1% cwt. per acre.” For
comparison, it may be stated that on an average the
English hop lands yield about 7 cwts. per acre.

As an instance of the losses caused by fungotd pests, we
may allude to the much-dreaded Peronospora infestans.
There is no doubt that ‘the potato disease in a bad year
affects the whole community; but it falls with crushing
force upon the large growers, for the potato is always
an expensive crop. The amount paid away in 1880 in
consequence of the failure of the preceding year, was
£2,847,027. Yet in 1885, after a smaller area by 18,987
acres, £727,806 sufficed to make good our requirements.
This enormous difference of £2,119,221 roughly indicates
the loss sustained by home potato-growers in 1879; and
that season had been preceded by several other scarcely
less calamitous years.” ;

Therefore nothing more need be said of the practical
utility of the subject discussed in the following pages.

The main object of this volume is to detail, in a concise
form, the life-histories of the principal insect and vege-
table foes of the farm, and to give an account of the
means for destroying them or preventing their attacks.

The microscope being of such practical utility for the
proper study of parasitic fungi and insects (and especially
the former), a short chapter has been added concerning
its use as a means of examining and studying the various
parasitic fungi and insects detailed in the present volume.
In my opinion, the best objectives are those made by Zeiss

PREFACE. vii

of Jena; in fact for clearness of definition they are unsur-
passed by any other maker.

No author could well approach the subject of economic
biology without consulting the works of Berkeley, Cooke,
Curtis, De Bary, Lindeman, Ormerod, Plowright, Riley,
Smith, Taschenberg, Westwood, Whitehead, Woronin,
and others: to these, I take this opportunity of acknow-
ledging many obligations.

My best thanks are given to Dr. Oarl Zeiss, Dr. K.
Lindeman (Professor in the Academy of Agriculture,
Moscow), Messrs. S. T. Griffiths, G. F. Strawson, C.
Whitehead, F.L.S., J. E. Mason, L. O. Howard (Depart-
ment of Agriculture, U.S.A.), B. P. Galloway, and the
Hon. N. J. Colman (formerly Commissioner of Agriculture,
US.A.), for valuable information.

I may add, that I have received the constant assistance
of my wife (née Frances E. Wright), whose knowledge of
botany has been no mean help to me in many ways.

In conclusion, I hope that the present volume may
prove useful in helping farmers and others to increase

the produce of the soil by preventing or curing those — -

diseases caused by the attacks of numberless farm pests.

A. B. GRIFFITHS.

CONTENTS.

CHAPTER I.
PAGB
Intropuction—Tue Scorr or raz Book—NoMENCLATURE
CHAPTER II.
Tue Disrases or Leguminous Crops—THE Parasites or Brans,
Cuover, Lucerne, Pras, TREFOIL, AND VETCHES ‘ ‘ 9

CHAPTER III.

Tue Diseases or Roor Crors—THeE Parasites oF BEETROOT,
Carrots, Mancen, Onions, Parsnips, Potatoes, AnD Turnips 33

CHAPTER IV.
Tue Diseases of GRaMINEous Crops—THE Parasites oF Bar-
LEY, GrassEs, Oats, Ricz, Ryz, anpD WHEAT. 5 « IT
CHAPTER V.

aE Diszases oF MisceLtangsous Crorps—TuHe Parasites or
Asparacus, CaBBacEs, CELERY, Cucumbers, Hops, Lettuces,
AND TomaTors . . - 7 é é . . . 133

CHAPTER VI.

Conctupine Remarks—TuHe Microscore anp its Accessories. 159

INDEX. : . . 5 . é 2 : : . 163

THE DISEASES OF CROPS.

CHAPTER I.
INTRODUCTION.

THE object of the present book is to give, in a concise
form, an account of the “doings” of the more important
members of the animal and vegetable kingdoms which
are injurious to farm crops.

As the scope of the volume is limited, it is not proposed
to include the life-histories of the organisms which prey
upon fruit and forest trees, as these do not concern the
majority of British farmers.

After describing the life-history of each “ insect” and
“fungus” and their modes of attack, various methods
will be given for the prevention and cure (as far as pos-
sible) of each disease.

By prevention is meant, those methods of cultivation,
etc., which will procure the production of strong, vigorous
and healthy plants, capable of resisting the attacks of that
‘unseen mist of organic forms.”

By cure is meant a description of the various re-agents,
etc., which are capable of destroying farm pests without
causing injury to the crops themselves.

The vine is liable to be attacked by some 350 parasitic
fungi in addition to the Phyllovera and other animal

1 B°

2 DISEASES OF CROPS.

pests! Happily our English farm crops have not such
an array of deadly foes as the vine. The wheat has its
“ mildew,” its “ smut,” its “ canker,” besides such animal
foes as the corn-weevil, the corn fly, the wire-worm, and
the Hessian fly. The potato has its Peronospora, its
Colorado beetle, etc.

The mildews and other fungi which infest farm crops
are all “ built”? more or less upon the same structural plan.
They take their origin in spores which are found in the
atmosphere, soils or water. The spores give rise to
hyphe (filaments), which live principally upon the albu-
minous substances found within the living cells of various
farm crops. Each hypha (in the majority of cases) is
composed of a variable number of microscopic cells placed
end to end, and each cell is composed of an external wall
or covering of a peculiar kind of cellulose, and contains
a living granular substance called protoplasm (“the basis
of life”). The cellulose of parasitic and saprophytic fungi
is of a different nature to that found in the higher plants.

The hyphe (produced from spores) branch and become
closely interwoven and twisted in all directions. This
‘mat-like” mass of hyphe is called a myceléwm,! and
gives rise to elongated cells springing vertically in the
air, bearing, at their free ends, spores.

As fungi, unlike the higher plants, contain no chloro-
phyll (green matter), they are incapable of living upon such
inorganic or mineral substances, as atmospheric carbonic
acid gas, water, ammonia and various soluble salts. Be-
cause they are incapable of “ manufacturing” albumin,

1 There is no connection between cells, which are in apposition in
two separate hyphex. This is one of the distinctions between fungoid
‘tissues’ and those of higher plants,

INTRODUCTION. 3

etc., they live parasitically on living or dead organisms,
thereby obtaining the required albuminous substance
requisite to sustain life.

Fungi living on dead or decaying organic matter are
termed saprophytes ; others infesting living plants, caus-
ing more or less serious disease in the host, are termed
parasites.

According to Dr. Sieber (Journal fiir Praktische
Chemie [2], 23, p. 412) certain common mildews have the
following compositions :—

| 1 1.

Albumin. . ........+. 29°88 28°95
Cellulose. . . . By eboa'en: He oe ck 39°66 55°77
SE 8 ee PRES. cite ek, har Wer Sas Ge. 4:89 0-73
Substances soluble inether . .. . 18-70 11:19
Substances soluble in alcohol. . . . 6°87 3°36
100°00 100-00

The analyses show that mildews contain a considerable
percentage of albumin, derived in the first instance from
the host-plant upon which the parasites live. The host-
plant thereby becomes diseased, and its vitality is greatly
impaired. The vitality of the spores of most fungi is very
considerable; and the spores are capable of being dried
up in the dust of the atmosphere for months, and it may
be years, without losing their vitality.

So far, we have spoken in a general way of the struc-
ture, etc., of the vegetable foes which are injurious to
farm crops. We now offer a few remarks concerning
those members of the animal kingdom which are un-
doubtedly the foes of the farm.

4 DISEASES OF CROPS.

The majority of the animal foes which cause disease in
crops belong to the great class of Insecta ; a few are mem-
bers of the Vermes (worms) and the Myriapoda (milli-
pedes).

“ Insects in their most complete character pass through
four stages or phases of existence—the egg, the larva
(maggot or caterpillar) stage, the chrysalis, and the
perfect state. In none of these, except the larval or
caterpillar stage, does the insect increase in size. :
After insects have come out of the chrysalis stage they
never grow—all the growth is done in the earlier stage
when they are caterpillars. If we sometimes meet with
two insects of the same species but of different size, the
difference is due to the supply of food which the cater-
pillar had during its growth, and is only a parallel case
to an ill-nourished child growing up into a stunted man.
Some insects, as the Aptera (wingless insects), pass only
through three stages : the egg, the ‘ younger stage’ and the
perfect form; and some of the intermediate orders also
attain perfection without passing through more than two.

“The egg is usually deposited externally, but in some

few cases it is hatched in the body of the parent; in some
others it is deposited at one period of the year, and the
progeny brought forth alive at another period.
In the larval stage, the insect casts its skin or moults
several times, after each casting attaining a sudden and
rapid increase of size. The larva does not always take
the form of a caterpillar or maggot. In some orders
(the Aptera, Hemiptera [bugs] and Orthoptera [cockroach,
dragon-fly, thrips]) it assumes a good deal of the appear-
ance of the perfect insect. In this imperfect metamor-
phosis it changes its skin as the caterpillars do, and it does
not assume a different form for the chrysalis stage.

INTRODUCTION. 5

“In the other orders (Diptera [two-winged flies],
Hymenoptera [bees, wasps, ants], Newroptera [caddis-fly],
Lepidoptera {butterflies and moths], Coleoptera [beetles])
the larva, on its last change of skin, assumes a new form
known as the chrysalis or pupa, in which stage it lies
dormant and nearly motionless, shut up like a body in the
shroud, until the last change takes place, when it comes
out as the perfect insect. This chrysalis in some cases
merely consists of the hardened skin of the animal itself,
and is left unprotected and bare in the open air, or in the
earth or other place of concealment; but in other cases
a cocoon or case is made by the larva for it, previous to
and in anticipation of the change, in some spun like the
cocoon of the silk-worm, in others composed of fragments
of earth or bits of wood, etc., glued together ” (Murray).

Insects in their perfect state, are distinguished from
other articulate animals by the possession of six legs
and two antenne (‘feelers’), and by the division of the
body into three distinct regions—the head, thorax, and
abdomen, of which the second bears the organs of ‘motion.
The mouth of the insects exhibits remarkable modifica-
tions. In some it is used exclusively for biting, in others
for suction, whilst in others again it is constructed for the
performance of both these actions, The eyes of insects
are compound and sessile; sometimes simple eyes are
added to them.

Insects are all unisexual ‘animals, Hermaphroditism,
where it occurs, is quite exceptional in its nature, and
very rarely gives rise to fertile individuals. The females
are usually larger and broader than the males, but in
most cases the structure of the apex of the abdomen at
once indicates the sex; besides the antenne and tarsi
(feet) often present well-marked differences in the two

6 DISEASES OF CROPS.

sexes. The reproduction of insects is essentially oviparous
(producing eggs), some are ovo-viviparous (Z.e., the eggs
are hatched and the young developed to a greater or
less extent within the body of the parent), and a few
(Aphides) are viviparous (producing living young) at
certain periods. The ravages of insects, which sometimes
occasion such serious panics, are explained by their enor-
mous fecundity. Sir Richard Owen, K.C.B, F.RS.,
estimated that a single Aphis in the tenth generation
produced no less than 1,000,000,000,000,000,000 (a quin-
tillion) young (Owen’s “‘ Invertebrata,” p. 44).

We propose to arrange the subject matter of this book
under the following headings :—

(a) The Diseases of Leguminous crops.
(8) The Diseases of Root crops.

(y) The Diseases of Gramineous crops.
(8) The Diseases of Miscellaneous crops.

In each case the diseases produced by the members of
the animal kingdom will be described first, and the fun-
goid diseases afterwards.

The subject of nomenclature throughout this book is
not thoroughly “orthodox,” and may possibly awaken
some controversy. As every scientist has his own views
on this subject, the author may be permitted to have his.
Concerning the nomenclature used it will be noticed that
no describers’ names are appended to the species described.
Thus Anthomyia Brassice, Bouché; Tipula oleracea,
Linnaeus; Peronospora Vicie, Berkeley; Peronospora
trifoliorum, De Bary, etc., become: Anthomyia Brassice ;
Tipula oleracea; Peronospora Viciw ; Peronospora
trifoliorum, etc.

The late Mr. Darwin was averse to the ‘ orthodox”
system of nomenclature, as the following quotations from

INTRODUCTION. 7

‘The Life and Letters of Charles Darwin” (vol. i. pp.
365-372) will show :—

(a) “ Why should naturalists append their own names
to new species, when mineralogists and chemists do not
do so to new substances ? ”

(8B) “I have come toa fixed opinion that the plan of
the first describer’s name being appended for perpetuity
to a species has been the greatest curse to natural
history.”

(y) “I mean to adopt my notion, as never putting ‘mihi’
or ‘ Darwin’ after my own species.”

Then again, as this is not a systematic work on the
subject of which it treats, no harm is done by “dropping”
the describers’ names generally attached to the organisms
alluded to. It will be our interest to learn more about
the things themselves than to ascertain the names—useful
or not—which the nomenclators have affixed to them.

“J’ai toujours cru qui on pourrait étre un trés grande
botaniste sans connaitre un seul plante par son nom,”
wrote the celebrated Rousseau in his “ Dictionnaire de
Botanique.” And if one can be a “very great botanist .
without knowing the name of a single plant,” so might
one be an entomologist, or a zoologist, if not great, at
least intelligent, without troubling oneself about any
system of “ naming” used by experts.

To conclude the chapter in the words of Mr. W. G.
Smith, F.L.S.: “All agriculturists should, if possible,
arouse themselves and learn something of the nature and
surroundings of plant disease. Till this knowledge is
acquired, and till agriculturists become alive to the
possibility of saving their crops from disease, little pro-
gress can be hoped for. We do not say that it is neces-
sary for every farmer to be a complete master of the

8 DISEASES OF CROPS.

anatomy and physiology of all the plants he grows, or to
be perfectly familiar with the life-history of every assail-
ing parasitic fungus or destructive animal, any more than
a householder should know all about the exact nature of
typhus, or diphtheria, or bacteria, bacilli, and disease
germs ; but as every householder at length begins to know,
amongst other facts, that an open drain is likely to prove
fatal to life, so every farmer should know, amongst other
things, that imperfectly drained fields and rotting vege-
table refuse mean disease and destruction to his crops.”

CHAPTER II.
THE DISEASES OF LEGUMINOUS CROPS.

(1) THE PaRASITES OF THE BEAN (Vicia faba).

The Bean Aphis (Aphis fabe, “black-fly,” “ col-
liers,” etc.) is a member of a tribe almost entirely com-
posed of the Aphides, or plant-lice. The Aphides are
all small animals furnished with six legs and a pair of
antenne, and usually with a pair of short tubes close to
the extremity of the abdomen, from which a clear sweet
secretion exudes. They all live upon plants, the juices
of which they suck, and when they occur in great num-
bers cause serious damage to the crops they attack.

Both sexes are sometimes winged and sometimes wing-
less. “But the most singular portion of the history of
these insects is their very curious manner of propagation.
In the autumn, male and female insects are found, furn-
ished with perfect generative organs; these copulate,
when the females lay eggs, which are hatched the follow-
ing spring. But, instead of producing individuals of both
sexes, these eggs give birth only to female insects, which
produce living young without any congress with the
male; the brood thus brought forth again produces living
young in the same manner, and this goes on throughout
the whole summer, without the appearance of a single

male insect. In the autumn again, male and female in-
9

10 DISEASES OF CROPS.

dividuals are produced, and the latter lay eggs which
are to continue the species until the following summer.”
From what has been said in the previous chapter con-
cerning the enormous fecundity of these insects, the
farmer can hardly wonder that his crops are completely
destroyed, from time to time, by these pests. Provided
with a warm moist summer and a plentiful supply of
food, the various species of Aphis multiply prodigiously.1

The Bean Aphis, like most insects, passes through three
stages of its life-history (é.e., larva, pupa, and perfect

Fig. 1.—Bran Apuis (Aphis fabe).

A. Male Aphis (enlarged).
B. Its natural size,
C, A young bean stem covered with Aphides.

state); but as far as their shape or general contour is
concerned there is little to distinguish one stage from
another. During the larval and pupal stages they have
no wings, but possess six legs. In these stages the colour
is from grey to black; becoming blacker as age increases.

The male insect (Fig. 1 A) is black, generally winged,

‘ For further details concerning the reproduction of Aphis, see
the papers of Balbiani (Annales des Sciences Naturelles, 1869-1872)
and of Huxley (Linnean Society’s Transactions, 1857).

LEGUMINOUS CROPS. 11

and measures about one-third of an inch across the ex-
tended wings. There are three kinds of females. (1) A
wingless black one. When examined by a magnifying
lens, the head, thorax, and abdomen appear to be fused
into one mass. This wingless female is viviparous (i.e.,
produces living young). (2) A winged viyiparous female,
which has a black body, and wings partly yellow and
partly green with brown veins. (3) A wingless female
which is oviparous (7.e., produces eggs). The oviparous
female only appears in the autumn; and the eggs produced
by her are hatched in the following spring. The wingless
females produced from these eggs then settle down upon -
the young “shoots” of the bean plants, and may cover,
in a very short time, a whole crop of beans with their
progeny. ‘These insects puncture the bean plants by
means of their suckers and extract the juices. This causes
a reduced state of vitality, which terminates (if the attack
is not stopped) in the failure of the crop.

Prevention.—(1) To prevent the attacks of the bean
aphis, the farmer should carefully remove thistles, curled
dock, gorse, and other wild plants on which the insect is
found. (2) To produce a healthy and vigorous growth
by the judicious use of manures. A good system of culti-
vation is always a means of lessening the attacks of this
insect.

Cure.—(1) As soon as the “ plague” makes its appear-
ance, cut off all the infested “tops ” and burn them. (2)
Where the crops are on a small scale, soot or soap-suds
are means of getting rid of the bean aphis. (3) Manuring
the land with a top-dressing of iron sulphate (; cwt. per
acre) has a tendency to produce a luxuriant growth; and
after this treatment the plants are rarely attacked by
this injurious insect.

12 DISEASES OF CROPS.

The Humble Bees (Bombus lucorum, Bombus
terrestris), whose nests are generally constructed of moss,
containing a few waxen cells, at times injure bean crops
by piercing the calyx of the flower, so as to extract the
nectar inside. This often causes the fall of the flower or
seedless pod.

Prevention.—The only means is to destroy their nests.

Fig. 2.—Bran Berrir (Bruchus granarius).
A. The beetle (enlarged).
B. Its natural size.
C. Larva (natural size).
D, Pupa (natural size),
E, Injured bean.

The Bean Beetle (Bruchus granarius) is a mem-
ber of a vast group of beetles, which embraces several
thousand species. The group is popularly known under
the name of weevils. ‘Many of these creatures are
extremely injurious to vegetables, both while growing
and when stored up in barns and granaries.”

The Bean Beetle (Fig. 2 A) attacks bean, pea, and

LEGUMINOUS CROPS. 13

other crops. It lays its eggs, in the spring, in the soft
young pods. After the hatching of the eggs, the larve
(maggots) feed upon the fleshy cotyledons of the seed, but
often leave the germ and husk intact. Each seed contains
only one maggot, which ultimately turns to the pupal
state within the bean or pea (Fig. 2 E); where it (the
pupa) hibernates until the spring, when it becomes a
perfect insect. The beetle then escapes from its enclosure
by gnawing its way out. The body of the bean beetle is
about one-sixth of an inch long, of a black hue with various
white spots. The front legs are of a reddish colour.
Cattle and other farm animals fed upon beans infested
with these insects are often seriously injured thereby. .
Prevention.—(1) Infested seeds should not be sown.
They are distinguished from sound ones by having round-
ish marks (about the size of the larva, Fig. 2 C) more
or less transparent. Maggot-eaten seed always produces
sickly plants, easily liable to be attacked by parasitic
fungi as well as animal foes. (2) As bean beetles are
frequently found largely in foreign seeds, such seed
should be carefully examined during the winter months.
Cure.—(1) “Tt is difficult to apply any remedy in the
field suitable to such a small insect; but the use of spent
hops as a manure, which is found serviceable in other
cases of insect-attack, might be of use here.” (2) Mr. W.
L. Wilson states that he found every insect dead after
treatment with a mixture of paraffin oil and water; ten
parts of water to one of paraffin oil. An easy method of
application would be the setting of two empty “ paraffin
barrels” on a stand, both fitted with a good large wooden
tap, which can be had for about 4d., whilst the empty
“paraffin barrels” are easily procured. The first barrel
should have one gallon of paraffin oil and ten of water

1d DISEASES OF CROPS.

poured into it, and the seed (peas or beans) should be put
in to soak an hour. The liquor should then be run off,
put into the second barrel, and this should also be filled
up with seeds; and so on, using the barrels alternately
until all the seeds have been soaked. The seeds thus
pass through the oil twice; once when they are poured
in, and again when the liquor is drawn off, because,
as the oil floats on the water, it comes off last; and the
beetles appear to be all killed by it without any harm
being done to the vegetable germ.

The Bean Weevils (Sitona crinita, Sitona lineata)
are often injurious to other leguminous crops besides
beans. These beetles devour the leaves of the infested
crops. For a description of their life-histories, etc., see
later in this chapter, under the heading of “ Pea Weevils.”

Julus pulchellus is the commonest of the “snake
millipedes,” and is one of the so-called “ false wireworms.”’
The true wireworm has only six legs, whereas Julus has
many. According to the late Mr. Curtis, Julus pulchellus
feeds upon the roots of beans, cabbages, and also upon the
roots of young wheat.

Prevention and Cure.—See the article under the
heading: ‘‘ The Diseases of Corn Crops.”

The Bean-Root Fungus (Ustilago faba). A con-
siderable amount of work has been performed in investi-
gating the nature of the nodular outgrowths upon the
roots of various plants. One of the earliest observations
in this direction was by Naegeli in 1842, who found that
the swellings upon the roots of Iris were caused by a
parasitic fungus. The peculiar nodules upon the roots of
various members of the Leguminosee have been examined
by Malpighi, De Candolle, Woronin, Kny, Treviranus,
Ward, the author, and others. Dr. Tschirch considered

LEGUMINOUS CROPS. 15

that these swellings were the storehouses for nitrogenous
compounds—these compounds being subsequently used up
in the ripening of the seed. But it has been shown by
subsequent research that Tschirch’s idea is erroneous, and
that these root-nodules are pathological or disease struc-
tures, caused by a microscopic fungus whose spores are, at
times, found in cultivated soils.

During the seasons of 1886 and 1887, field and garden
beans were attacked, more or less, by a fungus which

Fig. 3.—Roots or Broap Brans,
(Vicia faba) infested with a fungus causing nodular out-growths.

caused nodular out-growths upon the roots, and thereby
caused great injury to the crop (Fig. 3).

In the neighbourhood of Etton, near Peterborough, the
crops of winter beans were, during 1887, a complete
failure. Mr. G. W. Edgson (a well-known farmer) of
Etton sent the author a number of’ these bean plants for
inspection. They were about seven inches long. Mr.
Edgson wrote as follows: “The roots of the winter beans,
you will find, are covered with small boils, which appear
to be living upon the plant, and have kept the bean
plants in the stage you now see them. For the last few

16 DISEASES OF CROPS.

months the crop in this district has been a failure. Not
having seen anything like it before, I thought it would be
interesting for you to see them.” The author found that
these “ boils” were caused by the growth of a parasitic
fungus within the root, etc., of the bean plant (Chemical
News, vol. 56, p. 84; Lincoln Gazette, June 4th, 1887).
A complete study of the life-history of the bean-root
fungus has been made by Professor H. M. Ward, F.R.S.
(Philosophical Transactions of the Royal Society, 1887).

Prevention.—Avoid sowing maggot-eaten seeds or seeds
from infested crops. Such seeds cannot produce healthy
plants.

Cure.—(1) The author found that iron sulphate com-
pletely destroyed the spores, hyphe, and mycelia of this
fungus (Chemical News, vol. 56, p. 84). The iron sul-
phate should be used as a top-dressing (3 cwt. to the acre),
either mixed with sand or dry soil, or alone, when the
young plants are just above ground. (2) After the seed-
bed has been prepared, water it with a solution of iron
sulphate (from } to1 lb. of iron sulphate per gallon of
water). This will destroy any fungoid spores that may
be in the soil.

“Bean Brand” (Puccinia fabe) occurs about August
or September. It produces no spots on the bean plant, but
its sori (masses of spores) are surrounded by a ruptured
epidermis. The spores are black.

The Bean Mildew (Erysiphe Martii). For a
description of this parasitic fungus see later in this
chapter, under the heading of ‘‘ Pea Mildew.”” The Bean
Mildew attacks beans, peas, and other plants.

(2) Tue PARASITES OF CLOVERS.
The Clover Weevils. These small beetles devour

LEGUMINOUS CROPS. 17

the leaves of clover plants. They will be fully described
under the heading of “Pea Weevils.”

The Clover Eelworms (Tylenchus devastatrix
and Tylenchus Havensteinii, Fig. 4) are one of the causes,
if not the cause, of “ clover sickness.” They belong to a
group of nematoids or “ thread-worms,” known as the
Anguillulide. Drs. J. Kiihn (Biedermann’s Central-
. blatt filr Agricultur-Chemie, 1882, p. 270), Havenstein,
Taschenberg and others in Germany, as well as Mr.
Whitehead and Miss Ormerod in this country, consider
that “ clover sickness” is due to the attacks of eelworms.

Fig. 4.—Crover ‘‘ Eznworms ” (enlarged).
One of the causes of “ clover sickness.’

These eelworms of clover have rather elongated rounded
bodies which taper towards each end: they are not divided
into segments (like the true worms), and although they
are devoid of limbs, they have considerable powers of
locomotion. These nematoids are found on and in the
leaves and stems, as well as in the roots of clovers. These
organisms thrive only in the living portions of plants,
where they extract the plant-juices by means of their
suckers, thus causing a diseased condition of clover crops.
The nematoids of clover are never actually parasitic,

although they seriously injure these crops. It is only
c

18 DISEASES OF CROPS.

during the pairing season that they become parasitical,
for then they require an abundant nitrogenous food in
order to develop their sexual organs; and hence they are
found in the sexual state only within the tissues of clover
and other plants. During the winter the sexless worms
appear to live or hibernate in moist earth (Kiihn). The
female multiplies with great rapidity so long as the store
of food lasts. It appears that their power of fecundity is
in direct proportion to the quantity of living organic
nitrogen they are able to obtain. When the food is ex-
hausted the last hatched young wander away and attack
other plants, or assume the “dormant” condition until
another season. The eggs are always laid within the
host-plants. These give rise to larvae which are “ more
blunt at the extremities than the mature eelworms.”

The clover eelworms are possessed of very great tenacity
of life. According to Dr. C. Devaine (‘‘ Recherches sur
VAnguillule du blé niellé”) certain species of Tylenchus
may be exposed to —4° F. “for several hours, without
destroying their vitality. About 148° F., however, is the
maximum of heat in which they can exist.” Helworms
appear to be able to retain their vitality for several years ;
and Dr. Kiihn (Ueber die Wurmkrankheit des Roggens)
found that Tylenchus devastatriz retained its life for two
years in a state of complete desiccation, and much longer
in damp earth.

“With respect to infested clover plants . . . some
of the eelworms would remain in the leaves and stems left
in the plants after the first and second ‘cuts’ had been
mown. These, together with any that may have escaped
into the ground, are buried by the plough, and are brought
up again by a future ploughing in course of time to the
reviving influences of air and light. It is most probable

LEGUMINOUS CROPS. 19

that eelworms being in the stalks of clover made into hay
are taken also into the fields in the nose-bags of cart-horses,
and in the fodder supplied to folded sheep, as well as in
the manure from animals fed in yards with this hay”
(Whitehead).

Prevention.—(1) Rotation of Crops. Lawes and Gilbert
in their paper on “clover sickness” (Journ. Roy. Agric.
Soc., vol. xxi.) state, ‘that as far as our present knowledge
goes, the only means of insuring a good crop of red clover
is to allow some years to elapse before repeating the crop
upon the same land”; and Mr. Whitehead states that
“oats should also be avoided for some time, especially
where deep ploughing cannot be resorted to.” (2) Farm-
yard manure from horses, etc., fed upon clover and oats
infested with these nematoids is ‘‘a very common means
of spreading infestation.” The manure derived from these
crops should not be used for leguminous and cereal crops;
but may be used for root crops. (3) The clover nematoids
also infest the common daisy, crowfoot, shepherd’s purse,
and similar weeds. These should always be destroyed as
far as possible. (4) “The plants upon clover leys where
‘clover sickness’ has prevailed, should be buried deeply,
in order that they may not be dragged up again to the
surface by the harrows catching in their long roots. This,
of course, cannot be done upon some light chalk and other
soils where the surface mould is shallow, but it should be
carried out as far as possible.”

1 For further information concerning the life-history, etc., of
various nematoids, see Dr. Bastian’s ‘‘ Monograph” in Transactions
Linnean Society, vol. xxv.; Schneider’s Monographie der Nematoden,
1866; Claus’ “ Ueber einige in Humus lebende Anguillulinen” (Zeit-
schrift fiir Wissenschaftliche Zoologie, vol. xii.) ; and the paper by Dr.
Ritzema Bos in the Biologisches Centralblatt, vol. vii., No. 9.

20 DISEASES OF CROPS.

Cure.—(1) Before clover leys and oat stubbles are
ploughed in, they should be treated with a liberal dress-
ing of common salt or quicklime. By this means a large
number of, if not all, the nematoids are killed. (2) Kiihn,
Oehmichen and others (Biedermann’s Centralblatt fiir
Agricultur-Chemie, 1882, p. 270) recommend strong
manuring with kainit in cases of “ clover sickness.”

The “White Worms” of Clover. Professor A.
Harker, F.L.S., in Nature, vol. 40 [1889], p. 11, writes
that it is most probable that certain members of the
Oligocheta,| and more particularly Enchytreus Buch-
holzii, attack the roots and stems of clovers, vegetable
marrows, and other plants. This “white worm ” is about
14 inch long, and is supposed to injure the plants by
“sucking the fine root-hairs.” The “white worms” appear
to like the more or less decayed roots of plants, rather
than healthy ones; although the latter harbour a few
specimens. Harker says there is “but little room for
doubt that these small Oligochete are one cause of the
decay of the clover of Rothamsted.”

Prevention.—(1) A good system of draining the land
will no doubt lessen the activity of these so-called “white
worms.” (2) Produce a healthy and vigorous growth by
using pure seed and suitable manures,

The Clover Dodder (Cuscuta trifolii, Fig. 5) is a
member of the natural order Convolvulacew, although
it is a parasite. Clover dodder is incapable of elabo-
rating albuminous and carbonaceous substances from
such inorganic materials as: carbonic acid, water, am-
monia (or rather nitrates) and certain salts, like the
higher plants.

1 The earthworm belongs to this natural order.

LEGUMINOUS CROPS. 21

The twining stem of dodder is of a yellowish colour,
containing (in the spring and summer) clusters of pinkish,
funnel-shaped flowers, and is provided with suckers (Fig.
5 B) which are used for extracting nourishment from the
host upon which it lives. The seeds of dodder have a
rough surface, and are smaller than those of the clover
plant. The seeds of both clover and dodder are of a
brown colour, but the former have a smooth surface.

Fig. 5.—Ciover Dopper (Cuscuta trifolii).

A. Dodder entwined round clover.
B. Suckers.

C. Clusters of dodder flowers.

D. Seeds of dodder, x 2.

When the dodder has settled upon the clover plants, it,
at first, grows at about the same rate as the host; but
after a time the increase of its branches and suckers far
exceeds the growth of the clover.

The suckers pierce through the cellular tissues to the
central pith of the clover stems; and there the parasite
is nourished at the expense of the host. “The dodder
completely drains out the elaborated juices of the clover,
and kills it by exhaustion.”

22 DISEASES OF CROPS.

Dodder rarely produces seed in Great Britain, but its
stems are often perennial. ‘In the early stage of its
existence dodder is not a parasite, for after the germina-
tion of its seed, it grows like an ordinary plant, sending
its roots down into the soil, from which it draws its
nourishment. This state of existence, however, is short,
for unless it meets with some congenial plant to which it
can attach itself, and from which it can draw nourish-
ment, it withers and dies.”

Prevention.—(1) Dodder grows upon other plants be-
sides clover: viz.—nettles, broom, furze, yellow bedstraw,
sow-thistles, etc, These should be removed from all lands
growing clover. (2) Continental clover seeds often con-
tain those of dodder. The latter should be sifted away
as far as possible.

Cure.—(1) “The Continental remedy is to dissolve
iron sulphate in water, at the rate of 1 lb. to the gallon,
and water the infected spots with the solution. This
kills the dodder and leaves the clover uninjured.” (2)
“Carefully collect and burn all the patches of dodder
after the crop has been removed, and then give the field
a good clean fallow. All such operations as harrowing
and raking do harm, for instead of extirpating the dodder,
they only further the mischief, as it is well known that if
the dodder is cut into a hundred pieces, each piece will
go on growing and become a separate plant.”

The Clover Mildew (Peronospora trifoliorwm,
Fig. 6) is a fungoid growth, and is one of the causes of
“clover sickness.” P. trifoliorum grows within the
leaves of.the clover plant, although it sends out aérial
branches (conidiophores) through the stomata (openings)
which are found largely on the under surface of the leaves
(Fig. 6 a), The conidiophores bear oval spores (conidia,

LEGUMINOUS CROPS. 23

Fig. 6b). These spores germinate when provided with
moisture and a suitable medium, and ultimately give rise
to conidiophores. The spores of the clover mildew, like
those of every fungus, consist of living protoplasm
surrounded by a cellulose covering. Near the end of the
season, true sexual organs (analogous to the carpels and
stamens of the higher plants) are produced from certain
hyphe within the leaves of the host-plant (Fig. 6 C, d).

Fig. 6.—Ciover Mitpew (Peronospora trifoliorum).
One of the causes of “ clover sickness,’’ x about 200.

The largest of these organs (Fig. 6 C’) is the odgonium, or
egg-cell; and the smallest (D’) is the antheridium, or male
cell. The former contains an odsphere. After the anthe-
ridium and odgonium have been in contact, and their
contents thoroughly commingled, the antheridium dies
away; but the odgonium increases in size and becomes
an odspore or resting-spore. The odspores fall to the

24 DISEASES OF CROPS.

ground in the autumn, and hibernate until the summer,
when they germinate on clover leaves, giving rise to
internal hyphe and mycelia, which in due time bear
conidia.

The growth of this mildew injures the clover plant in
several ways: (1) By simple contact it causes putre-
factive changes to occur within the tissues of its host,
(2) It clogs up the organs of assimilation and transpiration
(the stomata), and thereby greatly interferes with these
physiological functions, which are necessary for a healthy
and vigorous growth. (8) This mildew produces brownish
spots on clover leaves.

Prevention.—(1) Avoid thick planting, for it favours the
attacks of P. trifoliorwm. (2) Burn all clover refuse, as
it harbours the resting-spores of this fungus. (3) The
land should be well drained, as P. trifoliorum is “ fond”
of moisture.

Peronospora exigua was discovered by Mr. W. G.
Smith, F.L.8., and is very similar in its life-history to
the clover mildew. It is much smaller than Peronospora
trifoliorum, and causes putrefactive changes within the
cells of the leaves of clover. This fungus, whose conidia
are almost round, produces odspores like the clover
mildew.

Besides the two species of Peronospora described,
several other fungoid growths are, or have been, put
down by various observers, as the cause of “ clover sick-
ness.” From what has already been said, there is little
doubt that “ clover sickness” is due to a variety of causes,
and not to any single parasite (animal or vegetable).

(3) THe Parasites or LUCERNE (Medicago sativa).

The animal and vegetable foes of lucerne are the same

LEGUMINOUS CROPS. 25

as those which infest clover, consequently they do not
require special description.

(4) Tue PARASITES OF THE Pra (Pisum sativum).

The Pea Moth (Grapholitha pisana, Fig. 7).
During the month of June this small moth will be seen
hovering about the flowers of field and garden peas. Ac-
cording to Dr. Taschenberg (Praktische Insekten-Kunde),
the female moth lays three eggs on each young pea-pod.
In about a fortnight the eggs are hatched, and the larve
or caterpillars, which are provided with mouths well
adapted for chewing hard substances, gnaw their way into

Fig. 7.—Psa Mora (Grapholitha pisana).

A. Pea Moth (slightly enlarged).
B. Caterpillar eating pea (nat, size).

the pod, and then begin to regale themselves upon the
“ fleshy ” cotyledons of the seeds (Fig. 7 B).

The caterpillars of this moth are of a yellow colour, with
black heads. Their bodies are divided into segments, and
each segment has a certain number of brown dots and a
few hairs. The caterpillars finally retire to the earth,
where they change their skins, and ultimately spin
cocoons. Within these cocoons they hibernate until the
following spring. During the spring they pass into pupe,
and appear finally as moths (Fig. 7A) about the month
of June.

The larva of the pea moth causes what is known as
“ maggoty ” or “ worm-eaten ” peas.

26 DISEASES OF CROPS.

Prevention. — (1) Deep-digging or ploughing, before
winter, is effectual in destroying the pupe of this moth.
(2) Raking over the ground after the pea crop has been
gathered brings the caterpillars to the surface. These are
sure to be cleared away by birds. (3) Rotations of crops.

Cure.—(1) It has been stated that either quicklime,
sulphur, or soot placed along the rows of peas, after a
shower of rain, has proved effectual in keeping off an
attack of this insect. (2) Syringing the plants (at the
end of May) with a mixture of paraffin oil and water de-
stroys the pest.

The Pea Beetle (Bruchus pisi) belongs to the
same genus as the bean beetle (already mentioned), and
follows a similar life-history. The larva is white.

The Pea Weevils (Sitona crinita and Sitona
lineata), These small beetles (Fig. 8 A) devour the leaves
of pea and bean crops, by eating everything except the
woody midrib. Sitona lineata (Fig. 8 B) is the largest
of the two species, is of a yellow colour, and has about ten
dotted stripes along the elytra. The legs and antenne
are of a red colour. Sitona crinita is smaller than the
preceding species. It has grey elytra, spotted with black,
and covered more or less with hairs. These beetles feed
during the day, and at night retire to rest in the ground.
They are very sensitive to sound, and if approached they
usually drop from the leaves to the ground. The Sitones
pair in May, and a little later the females deposit (?) num-
bers of white eggs.!

Prevention. — Liberal manuring engenders a healthy
and vigorous growth. This may be a means of preventing
serious injury to the young pea-plants.

1 Little is known of the larval and pupal stages of these beetles.

LEGUMINOUS CROPS. 27

Cure.—(1) As the beetles retire to the ground at night,
treat the ground with lime, gas-lime, soot, or a mixture of
lime and soot. These substances destroy the beetles. (2)
Paraffin oil mixed with soil has also proved an effective
remedy against the ravages of these beetles.

The Silver Y Moth (Plusia gamma). The cater-
pillars of this moth, which are of a green colour, feed upon

Fig. 8.—Srrirep Pea Weevin (Sitona lineata).

A. Pea Weevil (natural size) devouring leaves of pea-plant.
B. Pea Weevil (enlarged).

the leaves of peas, beans, sugar-beets, linseed, and hemp.
Towards the end of the caterpillar stage, each caterpillar
spins a cocoon on a leaf of the infested plant, and in it
changes into a chrysalis. Plusia gamma, in any one of
the three stage of its life, rarely does much damage to crops
in Great Britain, although, according to Dr. Lindeman,

28 DISEASES OF CROPS.

the larva of this insect causes considerable damage to the
crops of Russia.

Prevention.—As the caterpillars feed upon nettles and
low-growing grasses, these should be cleared away.

Cure.—A good dusting with lime or soot is a sure
remedy for this pest.

The Pea Mildew (Erysiphe Martti, Fig. 9) is very
destructive, as it ‘grows on both sides of the leaves,”
causing white spots. The spores of this fungus throw out

Fig. 9.—Pra Mmprew (Erysiphe Martii).

. Oidium stage of the Pea Mildew, showing mycelium and spores.
. Conceptacle, or the perfect stage of the mildew.

. Section of the conceptacle, showing asci containing spores.

. An ascus with spores.

samp

hyphe, which are provided with suckers. These suckers
(haustoria) pierce the epidermis of the host-plant, and
thereby impede its growth. The hyphe soon produce a
mat-like mycelium within the leaves of the pea-plant.
During the early summer the mycelia give rise to a num-
ber of vertical groups of conidia or spores (Fig. 9 A).

LEGUMINOUS CROPS. 29

The formation of mycelia and spores constitutes the first
stage of the life-history of the pea mildew.

Later, and under favourable circumstances, the mycelia
produce a number of globose bodies (the conceptacles or
perithecia) of a brown colour. Under the higher powers
of the microscope the conceptacles are similar in appear-
ance to Fig. 9 B. Within each conceptacle there are a
number of oval-shaped bodies (asci) containing spores (see
Fig. 9,C and D). After a time these conceptacles fall to
the ground and hibernate until the following spring or
early summer. Then they burst, and the spores are set
free, to be wafted about by air-currents, until they fall
upon a suitable medium for germination to take place.
These spores produce the mycelium of the first stage of
the life-history of this fungus.

Erysiphe Martii causes immature decay, besides seriously
interfering with the processes of transpiration and assimila-
tion, and thereby prevents the growth of the host-plant.
This fungus attacks beans, melilot, peas, and other plants.

Prevention.—(1) Destroy all infested matter from the
previous year’s crops. (2) Clear away weeds, and destroy
them by fire. (3) As the fungus has been seen growing
inside the pods of peas, steep the seed peas before sowing
in a solution of iron sulphate (1 Jb. of iron sulphate to a
gallon of water). This will destroy the conceptacles and
spores of the fungus.

The Pea Mould (Peronospora vicie, Fig. 10) is
the fungus which causes brown spots on the leaves of
the pea-plant and other legumes. “ Damp, close weather
favours the extension of this fungus, and dry weather
retards its growth.” The life-history of P. vicie is
similar to that of the clover mildew already described.
Like all the Peronosporee, it grows internally in living

30 DISEASES OF CROPS.

plants, “sucking” their juices, and thereby causing
disease,

Prevention.—(1) Destroy all refuse from the pea crop,
as it harbours the resting-spores of this fungus. (2) Farm-
yard manure, from cattle fed on vetches and peas, should
not be used for manuring land required for peas and
vetches. The reason of this is, that the resting-spores of

Fig. 10.—Prronosrora viciz,

The mould of vetches and peas (causing brownish patches on the leaves, etc.).
A. Spore germinating, x about 154.

the fungus, if present on vetches and peas, pass through
the alimentary canal without being destroyed.

Cure.—When the crops are above ground, give them a
top-dressing of iron sulphate (3 cwt. per acre). This gene-
rally destroys most fungoid growths.

(5) THE PARASITES OF TREFOIL (Medicago lupulina).

Several parasites which attack clover are foes of trefoil.

LEGUMINOUS CROPS. 81

The Trefoil Weevil (Apion flavipes, Fig. 11)
belongs to a large family (Apionide) of small beetles.
Many of them do not exceed one-eighth or one-twelfth of
an inch in length. They are wingless, but possess well-
developed wing-cases (elytra). Both the head and thorax
are comparatively small and narrow. The former is pro-
longed into a rostrum (snout) of considerable length. The
antenne form lateral appendages to the rostrum (Fig. 11 B).

Fig. 11.—Treror Weevin (Apion flavipes).

A. Larve of Apion feeding on trefoil.
B. The beetle (enlarged).

The wing-cases are of various hues (green, blue, black, or
red).

The larve (Fig. 11 A) of Apion flavipes feed on and
are very destructive of trefoil. The perfect insect (imago)
is black, with red legs.

Prevention.—Liberal manuring and the use of soot and
lime tend to lessen the attacks of this insect.

The Trefoil Moth (Zygena trifolii). “This moth
flies about in the day-time, and has deep metallic green or

32 DISEASES OF CROPS.

blue fore-wings marked with several roundish, bright-red
spots.” The larva (caterpillar) feeds upon the leaves of
trefoil and various herbaceous plants.

(6) THE PARASITES OF VETCHES OR TARES
(Vicia sativa).

The parasites of this crop are similar to those of the
pea. Peronospora vicie, already described under the
name of the “ pea mould,” attacks Vicia sativa as well as
other plants.

So far we have surveyed the life-histories of the prin-
cipal parasites which injure leguminous crops. To con-
clude this part of the subject we quote from Professor
P. J. Van Beneden’s Animal Parasites and Messmates
(English edition, p. 85): “The parasite is he whose pro-
fession it is to live at the expense of his neighbour, and
whose only employment consists in taking advantage of
him, but prudently, so as not to endanger his life. He is
a pauper who needs help, lest he should die on the public
highway ; but who practises the precept—not to kill the
fowl in order to get the eggs. . . . The beast of prey
kills its victim in order to feed upon his flesh, the para-
site does not kill; on the contrary, he profits by all the
advantages enjoyed by the host on whom he thrusts his
presence.”

CHAPTER III.

THE DISEASES OF ROOT CROPS,

(1) Tue ParasiTes or Beetroot (Beta vulgaris).

The Beet Fly (Anthomyia bete, Fig. 12). The
larvee of this insect feed upon and burrow into the tissues
of the leaves of beet plants, causing great destruction to
the crops. They are about one-third of an inch long, and
are devoid of legs. The eggs (Fig. 12 B) are small, oval,
white bodies with hexagonal-like markings. They are

o ®

Fig. 12.—Brrer Fry (Anthomyia beta).

A. Beet Fly (nat. size).
B. Eggs, x 4.

laid on the under surface of the leaves, and when hatched
(t.e., in five days) the grubs attack the parenchyma or soft
parts of the leaves, and thereby interfere with the life
and nourishment of the plant.

Under favourable circumstances, during the summer,
the perfect insect (Fig. 12 A) is developed from the pupal
stage in about fourteen days; but if the transformation
from the larval to the pupal stage occurs late in the

season, the pupa hibernates in the ground until the

34 DISEASES OF CROPS.

following season. Pupation may also take place on the
leaves. The beet-fly attacks the plants in the following
manner: “After the beet plants have been singled and
begin to show vigorous growth, with broad leaves, they
suddenly droop, and have a withered appearance. Upon
examination it will be found that there are white blotches,
like blisters, upon the leaves, caused by maggots lying
snugly within their tissues, from which they have ex-
hausted the juices and extracted the chlorophyll, or green
colouring.” ‘The perfect insect is about the size and
shape of a common house-fly. It is dark-grey, with black
hairy legs, having yellow antenne with black tips. The
femora (thighs) of the female are yellow.”

Prevention.—(1) Before growing a crop of beetroots
plough in a green manure of buckwheat. This destroys
the pupe of the beet-fly. (2) An observer in the
Agricultural Gazette (Aug. 18th, 1884) writes: ‘“ Any
fertilizing application will do good which will act at once
in furnishing nourishment to the plant, and thus keep it
continually replacing by new growth the leafage which
is destroyed by the maggots. Nitrate of soda appears to
do best; but as the action of fertilizers depends on having
rain at the time to wash them down to the roots, it is
better to have previous good treatment of the land to
trust to.” (3) ‘ Many weeds (thistles, sow-thistles, dande-
lion, etc.) serve as breeding-places for this insect, and
should therefore be kept from the neighbourhood of dung
heaps and beet or mangel fields.”

Cure.—Wash the plants with mixtures of mineral oil
and a solution of soft soap. The proportions of this mix-
ture are 5 lbs. of soft soap and from 1} to 2 gallons of
paraffin oil to 100 gallons of water. This should be “ put
on with the ordinary hop-washing machine, like a garden-

ROOT CROPS. 35

engine, with a long hose attached to it, or with the
Strawsonizer.”’

The Beet Carrion Beetle (Silpha opaca, Fig. 18)
is found during the spring on putrefying animal matter
(hence the name ‘“carrion”’), the roots of trees, etc. The
beetles are of a dark-brown colour. On opening the wing
cases, the posterior end of the abdomen is of a dull-red
colour. The female lays the eggs in decomposing matter,

Fig. 13.—Bzxr ‘ Carrion” BrernE (Silpha opaca).

A. The beetle (about the size of nature).
B. Larvee (nat, size) feeding on leaves of beetroot.

and these give rise to larve, which attack and seriously
injure the young leaves of beet plants. In appearance
the black larvee are somewhat like the ordinary wood-lice,
only smaller (Fig. 13 B). They turn to the pupal stage
in the ground.

Prevention.—(1) Liberal manuring in the early stages
of growth is a means of preventing the attacks of this
pest. (2) The farmyard manure used for this crop should
be thoroughly fermented.

36 DISEASES OF CROPS.

Cure.—Top-dress the plants with sulphur or a mixture
of lime and soot.

The Silver Y Moth (Plusia gamma) rarely causes
much injury in Great Britain, although the green cater-
pillars of this moth cause considerable damage to the
leaves of sugar-beets in the northern provinces of France.
During 1887 the author saw several crops damaged by
Plusia gamma in the suburbs of Paris.

The colour of the moth is silver-grey, with brown
markings. The eggs are laid in clusters on the under
surfaces of the leaves, where they are hatched in about a
fortnight.

Prevention and Cure.—See under the heading of “ The
Parasites of the Pea” (chap. ii.).

The Nematoid of Beetroots (Heterodera Schachti)
causes considerable damage to the roots of this crop. It
is a dimorphous worm; “ the male has the usual form, the
female resembles a lemon ” (Schacht).

The Beet-leaf Rust (Trichobasis bete) is a fungoid
growth, which causes yellow spots on the leaves of beets,
and ultimately ruptures the epidermis of the host-plant.
The spores are brown, and the fungus is common in
August and September.

(2) Tur Parasites or Carrots (Daucus carota),

The Carrot Fly (Psila rose, Fig. 14). The maggots
of this insect gnaw and burrow into the roots of this
crop. These burrows have the colour of iron rust. The
leaves of the invaded crops prematurely turn yellow,
owing to the diseased condition of the roots and the
lowered vitality of the plants. After a time the roots
shrivel.

The white maggot (Fig. 14 B) is legless, and is about a

ROOT CROPS. 387

quarter of an inch long. The maggot turns to the pupal
stage in the ground. During the summer the pupe are
transformed into perfect insects in about twenty-five days.
The female flies finally give rise to eggs, maggots, and
pup ; the latter hibernate in the ground until the follow-
ing spring. The yellow body of the fly is about a quarter
of an inch long, and carries two wings of a blackish-green
colour.

Prevention.—(1) Good cultivation. (2) After thinning
top-dress the crops with soot and nitrate of soda.

B

—

Fig. 14.—Carrot Fry (Psila rose).
A. Carrot Fly (enlarged).
B. Legless larva (enlarged).
C. Sagres section of a carrot, showing a “‘ burrow” made by the larve of
sila,

Cure.—(1) Mix one pint of paraffin oil with two gallons
of water, and water the plants with the mixture after
thinning. (2) Top-dress the crops with sand saturated
with paraffin oil. (3) “An injured crop should be lifted
early, the ground thoroughly limed and deeply ploughed.
This destroys the pups, and prevents a renewal of the
attack in some future season.” (4) Farmyard manure,
mixed with salt and ploughed into the land during the
autumn, destroys the pup.

38 DISEASES OF CROPS.

The Carrot Milliped (Julus terrestris, Fig. 15) is
one of the so-called “false wire-worms,” and is one of
the largest British species. It attacks carrots, parsnips,
and other root crops.

The Juli undergo a sort of metamorphosis, coming from
the egg either quite destitute of feet or furnished with
only three pairs of these organs. According to Dr. Savi,
the Juli occupy two years before the sexual organs are
perfected.

Prevention and Cure.—Green manuring with buck-
wheat destroys this pest.

The Carrot Moths (Depressaria daucella, De-

Fig. 15— Carnot Mitiiprp” (Julus terrestris).
Nat, size,

pressaria depressella, and Depressaria cicutella) lay
their eggs on the foliage of this crop, and the caterpillars
damage the leaves and the heads of the flower. “ When
disturbed they drop to the ground, and after a time, by
means of a gossamer thread left for the purpose, they re-
turn and renew their depredations.” The caterpillars of
the two first-mentioned species feed on the flowers and
seeds of the carrot plants. The larve spin webs so as to
fasten the umbels together, and then regale themselves,
destroying the flowers of the host-plant. The caterpillars
of both D. daucella and D. depressella are greenish-grey in
colour. The former are about half an inch and the latter
a quarter of an inch long. When full-grown, both species
change to the pupal stage in the flower-heads, or they

ROOT CROPS. 89

hibernate in the stems of the carrot plant until the follow-
ing spring. The moth of the first-named species is about
half an inch long, of a red-brown colour ; while the moth of
D. depresselia is the same length, but of a yellow colour.

The caterpillars of D. cicutella feed on the leaves of
the carrot plant, which they roll up. These caterpillars
are green in colour with black spots on each segment, and
they are half an inch long. The pup are brown, and
are to be found either in the coiled leaves or in cocoons
in the ground. The moths are about seven-sixteenths
of an inch long, with narrow wings of a reddish hue.
They make their appearance in June.

These three moths are known under the popular names
of “the carrot-blossom moth,” “the purple carrot-seed
moth,” and “ the common flat-body moth,” respectively.

Prevention.—Burn all infested stems, etc.

Cure.—Use dressings of soot, quicklime, or sulphur.

The Swallow-tailed Butterfly (Papilio machaon)
is a rather rare and brilliant creature. The colour of
the wings is yellow and black, with lines and spots, a
deep bluish-black band near the hind margin, and a
bright red round spot on the inner margin of each hind
wing. It is chiefly found in the fenny districts of
Lincolnshire, Huntingdonshire, and Cambridgeshire. The
larva or caterpillar of this butterfly is of a pale green
colour with black bands and orange spots. It feeds on
the leaves of carrot plants.

Prevention.—Destroy cow-parsnip and other umbelli-
ferous plants.

(3) THE PaRASITES OF MANGEL-WURZEL (Beta maritima
and Beta vulgaris).

The Mangel Fly (Anthomyia bete) has already

40 DISEASES OF CROPS.

been described. It destroys the foliage, and thereby
arrests the growth of the plant. :

Cure.—Mr. C. Whitehead, F.L.S., recommends washing
the leaves, by means of a garden engine, with a solution
of soft soap and quassia.

The Carrion Beetle (Silpha opaca), already de-
scribed, injures mangel-wurzel as well as beetroot.

The Club-Root of Mangel (Plasmodiophora bras-
sicw) is a fungoid growth which will be described later
on in this chapter (see “The Parasites of Turnips ”).

The Mangel-Leaf-Rust (Trichobasis bet) has
already been described among the diseases of beet-roots.

(4) Tue ParasiTes or Onions (Alliwne cepa).

The Onion Eelworms (Tylenchus allii), according
to Dr. Ritzema Bos, cause putrefaction to occur within
the bulbs. They are found in the parenchyma of the
bulbs and leaves. Much injury is done by these pests
to the onion crops of Holland.

Prevention and Cure.—See “ The Eelworms of Clover ”
(chap. ii.).

The Onion Fly (Anthomyia ceparwm) belongs to
the same genus as the beet fly. The eggs are laid in
April or May, on the lower leaves of the young onion
plant or on the ground. After hatching, the larva, which
are devoid of legs, and about three-eighths of an inch
long, feed inside the bulbs, having previously gnawed a
way into the interior. Here they reside from fourteen
to sixteen days, causing a considerable amount of
damage to the bulbs, which finally become rotten. After
the expiration of a fortnight’s residence within the bulb,
they leave it and enter the ground, and there turn to the
pupal stage. Ifthe grub turns to the pupal stage in the

ROOT CROPS. 41

autumn, it hibernates until the following spring. If, on
the other hand, it becomes a pupa during the summer, it
remains in this state from fourteen to twenty-one days,
when it becomes a perfect insect. The fly is nearly five-
eighths of an inch across the extended wings. The male
is grey in colour, with three dark bands on the abdomen ;
while the female is of a yellow colour.

Prevention.—(1) Rotation of crops, (2) “The most
successful method of cultivation is to trench the ground
for the onions in the autumn, working plenty of manure
into the soil, or placing a good layer at the bottom of the
trench.” (3) Raise all sickly-looking plants by means of
aspud. This will decrease the number of grubs, etc.

Cure.—(1) Applications of paraffin oil mixed with
‘water (1 pint to 2 gals.) have been the means of destroy-
ing this pest. (2) Soap-suds have also been recommended
as a remedy. (3) Soot, sulphur, and lime are powerful
insecticides.

The Putrefactive Microbe of Onions (Bacterium
allti, Fig. 16). It may be useful, in passing, to allude to
a microbe which is a destroyer of onions (when stored),
by causing putrefactive changes to occur within the bulbs.
This putrefaction ultimately gives rise to a greenish-
coloured slime over the surface of the decomposing
onions. This microscopic organism must therefore be
looked upon as an enemy of the farmer, market-gardener,
and others.

The author discovered this microbe upon onions kept in
a warm, damp, and dark place. The cells are each about
0:005 to 0:007 millimetre long, and about 0:0025 milli-
metre! wide. The organism has been called Bacterium

’ 1 millimetre = 0°03937 inch.

42 DISEASES OF CROPS.

allii, because it was discovered upon Allium cepa. It
grows tolerably well in sterilized nutrient agar-agar
(Japanese isinglass), and other cultivating media used by
scientists. Upon the surfaces of nutrient media, B.
allii produces a bright-green pellicle, and causes certain
chemical changes to occur in albuminous substances, The
microbe is chromogenic; 7.c., it produces a pigment (of a
green colour), by the decomposition of the medium upon
which it lives.

Fig. 16.—Purreractive Bacterium or Ontons (Bacterium allii).
A. The Bacterium under the high powers of the microscope.

B. Bacterium allii growing on nutrient agar-agar.

It appears that the whole function of this organism
is to decompose or disintegrate albuminous substances,
giving rise to certain products; viz., sulphuretted hydro-
gen gas (in small quantities), and a deliquescent alkaloid
of the following symbolic formula, C,) H,, N.

Bacterium allii is possessed of great tenacity of life,
for after an exposure to 32°C. (dry heat) for six months
the organism had not lost its vitality. Cold appears to

ROOT CROPS. 43

reduce its vitality considerably. When artificial cultures
were exposed to a temperature of —17° C. for one day, the
organisms were completely destroyed. An E.M.F.! of
3°3 volts (at 17°C.) destroyed B. allii when growing in
sterilized pork broth (neutral).

Prevention.—Onions, when stored, should be kept in a

Fig. 17.—Onton Mitpew (Peronospora Schleideniana).
A. The fungus growing from the base of an onion leaf.
B. Mycelium ramifying amongst the cells of the host-plant.
C. Stomata of leaf,
D. Conidia (spores). .

{x 50 diameters. )

perfectly dry place, or they may become a prey to this
microbe.”

The Onion Mildew (Peronospora Schleideniana,
Fig. 17). This fungus is closely allied to Peronospora
infestans (the potato-disease fungus), and, like all the

members of the Peronosporee, grows within the leaves
and stems of the host-plant. The onion mildew causes

1 An electro-motive force (see any small text-book on electricity).

2 For further information see Dr. Griffiths’ papers in the Proceed-
ings of the Royal Society of Edinburgh, vols. xv. and xvi.; and
Comptes Rendus, vol. ex,

44 DISEASES OF CROPS,

putrefaction among the microscopic cells of the leaves,
etc., as well as greatly interfering with the processes of
transpiration and assimilation. The onion mildew pro-
duces moist, greyish spots on the leaves of various species
of Allium, or, in other words, causes, by contact, the
complete decomposition of the leaves.

The mycelium (Fig. 17 B) ramifies amongst the living
cells of the leaves. It produces conidiophores (Fig. 17 A)
which bear aérial conidia (spores) Odspores or resting-
spores are produced by sexual reproduction, 7.c., by the
union of the antheridium with the odgonium, similar to
those already described in connection with the clover
mildew (see chap. ii.). The odspores are found in de-
caying onions.

Prevention.—(1) Burn all decomposing onion refuse.
(2) Good cultivation, with the seeds sown in the autumn,
produces strong healthy plants capable of withstanding
the attacks of this fungus in the following spring. (8)
Deep trenching.

Cure.—Manure the land, when the plants are a few
inches above ground, with half-cwt. of iron sulphate per
acre. The sulphate may be mixed with five to ten times
its weight of sand or dry earth, in order to obtain regular
distribution.

The Smut of eiiexe (Urocystis cepule) is allied to
the “ smuts,” etc., of corn, potatoes, and other plants. It
is more common in the United States of America, and in
France, than in this country. It produces amongst the
onions a blackish-brown dust after the harvest.

The Onion Mould (Mucor subtilissimus) grows on
Alliwmeepa, and possibly on allied plants. Another species
of the Mucorini is the mould of preserved fruits, etc.

The onion mucor produces a very fine mycelium, which

ROOT CROPS. 45

ramifies chiefly in the upper part of the bulb, causing
decay. Among this mycelium are numbers of black.grains
—the sclerotia, or masses of mycelia in a resting state.
Each sclerotium germinates by throwing out hyphe which
ultimately give rise (at their ends) to sporangia containing
oval sporidia (spores). The sporangia, when ripe, burst in
the air, and the spores are wafted about by air currents,
causing destruction to crops of onions. The spores ger-

Fig. 18.—'* Gartic Rust” (Puccinia miata).

A. Flower stalk (rd nat. size) showing the disease “‘ pustules”’ or sori.

hk. The same x 4 diameters. .

C. ‘Transverse section of small sorus. The epidermis of host-plant is broken
at 3 and 4, by the fungus whose mycelium is thickly matted amongst
the tissues of host.

1 and 2 show the two kinds of spores x 75.

minate on the host-plant, giving rise to hyphe, mycelia, and
sclerotia. The latter are capable of retaining their vitality
through the winter months, and germinate in the spring.
Prevention.—(1) Burn all infested onion refuse. (2)
Autumn sowing.
The Garlic Rust (Puccinia miata, Fig. 18) was

46 DISEASES OF CROPS.

discovered by a well-known fungologist, Mr. W. Phillips,
F.LS. (Gardeners’ Chronicle, July 14th, 1883), on Alliawm
schenoprasum (chives). The fungus covers the leaves
and flower stalks (Fig. 18 A and B) with brown spots.
These spots are caused by sori, or masses of spores, etc.,
which ultimately rupture the epidermis of the host-plant.
Each sorus (Fig. 18 C) is composed of a thickly matted
mycelium, which ramifies among the tissues of the host ;
and gives rise to a large number of brown bodies (more
or less club-shaped), which are morphologically spores,
although unlike the conidia of other fungoid growths.
These spores are called teleutospores, and are true resting-
spores. The teleutospores of the garlic rust are of two
kinds (Fig. 18, 1 and 2). One is divided by a transverse
septum, and the other is not so divided. These spores are
capable of hibernating for several months.
Prevention.—Burn all infested refuse.

(5) Tue ParasiTes oF Parsnips (Pastinaca sativa).

The Parsnip Leaf Miner (Lephritis onopordinis).
The members of the genus Tephritis are lively little flies;
and the species about to be described is one-sixth of an
inch long, of a brown colour, with green eyes, and two
transparent wings. The female lays her eggs within the
cuticle of the parsnip leaves, where they are hatched, pro-
ducing little pale-green maggots, which cause large blisters
upon the leaves. These blisters ultimately cause the com-
plete decay of the leaves. The pupa of this fly is of a
yellow-brown colour, and is found on the leaves of the
parsnip and in the earth.

There are several broods during the year. The pupz last
produced, hibernate in the soil until the following spring.

Prevention.—(1) Curtis recommended a dressing of tar

ROOT CROPS. 47

and sand to be put on the ground before sowing the seeds.
The odour of the tar is so offensive to insects that they
cannot endure soil impregnated with it. (2) Burn all in-
fested leaves.

Cure.—Dressing the Jand with gas-lime, soot, and lime,
destroys the pups of this pest.

The Parsnip Fly (Psila rose) has already been
described in this chapter (see ‘‘ Carrot Fly ”).

Fig. 19.—Minprw or Parswirs (Peronospora nivea).

A. Aspotted parsnip.
B. Conidiophore bearing conidia (spores). x 107.
C. Mature conidium dividing. x 334.
D. Conidium after division. The formation of zodspores, x 334,
E. Zoéspore with cilia. x 334,
The Parsnip Moths have already been described

under the heading of ‘Carrot Moths” ; and for still. fur-
ther information, see Dr. Riley’s Insect Life, vol. 1, p. 94.

The Parsnip Mildew (Peronospora nivea, Fig.
19) lives within the tissues of the host-plant. The fun-
gus first attacks the leaves, the hyphz of which soon

48 DISEASES OF CROPS.

make their way into the stems and roots of the parsnip
plants. The hyphe, or threads of the mycelium, are stout,
and are provided with numerous suckers, which cause
putrefaction to occur within the tissues of the host-plant.
When the roots are attacked, they become spotted (Fig.
19 A), and finally rotten. The mycelium sends out coni-
diophores (Fig. 19 B), bearing conidia, through the stomata
of the leaves, and thereby interferes with the processes of
transpiration and assimilation. The protoplasmic contents
of the oval-shaped conidia (Fig. 19 C) divide into a number
of portions, each of which produces a zodspore (Fig. 19 D
and E) provided with cilia (filaments), which enable them
to be carried about by aérial currents. The zodspores re-
produce mycelia.

Odspores (resting-spores) are produced, during the life-
history of Peronospora nivea, within the stems and roots
of the host-plant. This parasite of parsnips also attacks
parsley and other plants.

Prevention.—(1) Burn all infested refuse from previous
parsnip crops. (2) Destroy such weeds as cow parsnip,
goutweed, wild chervil, and wild angelica.

Cure.—See the treatment of the potato disease caused
by Peronospora infestans.

(6) Toe Parasites oF PotatoEs (Solanum tuberosum).

The Colorado Beetle (Leptinotarsa decémlineata,
Fig. 20) belongs to the Chrysomelidw, and is about half
an inch long, with wing-cases marked alternately in stripes
of black and yellow. The thorax is also yellow with a
black v-shaped mark in the centre, surrounded by several
smaller black marks. If the elytra (wing-cases) are opened,
the bright red wings will be seen ; this is one of the pecu-
liarities of this insect.

ROOT CROPS. 49

The female lays the eggs (Fig. 20 C) chiefly on the
under surfaces of the leaves of the potato plant. When
hatched, the eggs give rise to orange-coloured larve (Fig.
20 B). These feed upon the leaves, causing great havoc
amongst the potato crops of the United States of America.
The larvee turn to the pupal stage in the ground.

The Colorado beetle appears to be indigenous to North
America. Its original home was the Western States
(Oregon, Nevada, Arizona, and Colorado); but it is now to
be found in other States besidés those mentioned, and most
probably all over the North American Continent.

Fig. 20.—Cotorapo Brerie (Leptinotarsa decemlineata).
A. The beetle (nat. size).

B. Larva (nat. size).
C. Eggs (nat. size).

Tt was first identified in Great Britain by the late Mr.
A. Murray, F.LS., in 1877. Up to the present time
British potato crops have not suffered from the ravages of
this destructive beetle.

Cure.—Mix three ozs. of the arsenical compound (copper
arsenite) known as “Scheele’s green,” with two gallons
of water, and water the infested plants with the mixture.
For other remedies and the numerous appliances for dis-
tributing the same,—see The Fourth Report of the United
States Entomological Commission (pp. 120-321).

The Death’s Head Moth (Acherontia atropos) is

the largest moth in England, and, according to Swainson,
E

50 DISEASES OF CROPS.

the largest in Europe. It often measures from five to six
inches across the extended wings. The skin of the moth
is variegated with black, dark-brown and yellow; and
bears upon the back of the thorax a deep orange mark,
presenting no inconsiderable resemblance to the front of
a human skull. A. atropos “utters” a sharp squeaking
sound.

The larve (caterpillars) of this moth are also very large,
often measuring from four to five inches long, and as thick
as a man’s finger. They feed upon the leaves of the potato
plant during the evenings, but, according to Miss Ormerod,

2%
Fig. 21.—Potaro Frog Fry (Eupteryx solani).

A. Frog fly (enlarged).
B. Eggs (nat. size and enlarged).

“seldom cause any serious amount of damage.” They “are
provided with feet and strong jaws. The skin of the
caterpillar is of a pale yellow colour, with seven oblique
violet stripes along the abdominal segments, The larve
change their skins, and are transformed into the pupal
stage, at least one foot deep in the ground. For this
reason they have been termed subterranean pups, and are
often turned up in digging potato grounds. The pupa is
chestnut coloured. The perfect insect makes its appear-
ance from August to October.

Prevention and Cure.—(1) Handpicking. (2) Liming
the land destroys the pupze.

ROOT CROPS. 51

The Potato Frog Fly (Eupteryx solani, Fig. 21)
isa small green insect, measuring only one-sixth of an
inch in length. It is provided with four wings, two short
antenne, placed between a pair of brown eyes. There
are six legs. The posterior pair are very long, which
assist the insect in performing most extraordinary leaps,
—hence the name of “ frog fly.”

The eggs (Fig. 21 B) are white, and about one-twentieth
of an inch in length. The larva and pupa are both some-
what like the perfect insect in shape, provided with six
legs, two antenne (long), and a sucker. They are wing-
less. Hupteryx solani (in all three stages) lives upon the
juices of the leaves and stems of the potato plant, which
it pierces by means of its sucker.

Cure.—A dressing of lime, sulphur, or soot.

The Potato Disease Fungus (Peronospora infes-
tans, Fig. 22). The life-history of this fungus has been
thoroughly investigated by Rayer, Montagne, Berkeley,
De Bary, Smith, and others; but to Mr. W. G. Smith,
F.L.S. (who discovered the reproductive organs and the
odspores), is the honour of having made a thorough study
of this fungus.

The potato disease (the so-called “curl’”) makes its
appearance in July or August, especially in moist warm
weather; and commences its attack by settling upon the
leaves of the host-plant. The leaves become spotted
(blackish), and have a tendency to curl up. After piercing
into the interior of the leaves, the fungus spreads its
mycelium through the tissues of the stems and tubers of
the potato plants. Its growth is very rapid, and it pro-
duces in the host complete decomposition of the parts in
contact. with it.

If a transverse section of a diseased potato leaf (Fig.

52 DISEASES OF CROPS.

22) is examined beneath the microscope,! the mycelium of
the fungus will be seen ramifying among the cells of the
leaf. Wherever the mycelium comes in contact with the
cells of the host-plant, they become discoloured. This is

Fig. 22.—Porato Funeus (Peronospora infestans).

A to B. Transverse section of potato leaf, showing mycelium (spawn) of fungus.
A. Hore surface with two stomata (C) and conidiophores passing through
them.
D. Conidium (spore).
K. Zoéspore.
F, Oégonium and antheridium.
G. Pallisade parenchyma cells of leaf.
H. Spongy parenchyma,
{x 100 diam.)

due to the putrefactive changes caused by the presence of
this fungoid growth. The mycelium gives rise to aérial
hyphe (conidiophores) which bear conidia or spores (Fig.

1 In our opinion, the best ‘ objectives” for this and similar pur-
poses are those made by Zeiss of Jena.

ROOT CROPS. 53

22 D); and to reproductive organs (Fig. 22 F) within the
host-plant. The protoplasm of the conidia either divides
or gives rise to a hypha or “ germ tube” (Fig. 23). When
it divides it produces a number of zodspores provided with
cilia (filaments) (Fig. 23 B). The zodspores float about
in the atmosphere and thereby spread the disease. Ulti-
mately the cilia disappear, and the zodspores settle down
upon the leaves of the potato plant, giving rise to another

Fig. 23.—Potato Funeus (Pcronospora infestans).
Conidium dividing.
. Conidium producing zoéspores (after division).

Conidium protruding a filament of protoplasm.
. Odgonium (Q) and antheridium (3).

. Odspore (Resting-spore).

Odspore producing zodspores.

. Odspore germinating.

(x 300 diam.)

QA OO >

generation of mycelia. According to the late Rev. M. J.
Berkeley, F.R.S., the mycelium sometimes hibernates
and becomes perennial. Sexual reproductive organs are
formed from the cells of the mycelium within the host-
plant. They are generally to be found in the inter-
cellular spaces (Fig. 22 F, and Fig. 23 D). Fertilization

5d DISEASES OF CROPS.

takes place by the transfusion of the contents of the
antheridium into thé “odgonium. After fertilization, the
odgonium develops into an odspore (Fig. 23 EH). The
outer coat of the odspore thickens and may become
“spiny.” The odspore hibernates for nearly a year, and
then gives rise to zodspores or germinates by throwing out
a hypha (Fig. 23 F and G). The zodspores and hyphe
from the oéspore reproduce the disease in the next year’s
crop, if the external surroundings are favourable for their
development and growth.

The author has shown (Chemical News, vol. 53, p. 255)
that the spores, etc., of Peronospora infestans are capable
of being dried up in the dust of the atmosphere for several
months without losing their vitality. On the other hand,
if potato tubers infested with the mycelia of this fungus
are exposed to a temperature of — 10° C. (14° F) for a few
weeks, they are completely destroyed. Peronospora in-
Jfestans causes (as stated before) putrefactive changes to
occur within the tissues of the host-plant. The author
found lactic acid (in small quantities) in the leaves, etc.,
of diseased potato plants. It may be that lactic acid is
formed from the decomposition of glucose contained in
the sap of the host-plant. From this it appears that
parasitic fungi may cause the abnormal development of
compounds within the living cells of infested plants; and
thereby cause death by “ poisoning” (Chemical Hei,
vol. 53, p. 255).

Prevention.—(1) Sow only those varieties which are
hardy and have been proved to resist the attacks of P.
infestans. ‘“ Besides our potato-bearing Solanum tubero-
sum, there are, amongst the 700 species of Solanum,
about five which bear tubers—S. Commersoni, Maglia,
immite, verrucosum, Jamesi—of these, Solanum Commer-

ROOT CROPS. 55

soni has been cultivated in its native country (Chili) for
some time. Experiments have been made in England to
introduce some of these species and to cross them with
the ordinary potato, in order to obtain a product which
might possibly not be susceptible to the potato disease.”
According to Mr. J. G. Baker, F.R.S., Solanum Maglia
and S. Commersoni would suit the humid climates of
Great Britain and Ireland. They are both great disease-
resisters.

Nearly all the old varieties of cultivated potatoes either
fall a ready prey to the attacks of Peronospora, or have
become so unfruitful as to be scarcely worth planting.
The variety known as the “ champion” “has lost much of
its productiveness.” “The ‘regent’ is worn out; and
many of the newer seedlings of that class, although good
croppers, are at the mercy of a moist season.” Mr. Baker
states that Solanum tuberosum “in its present tuber-
bearing state is in a disorganized, unhealthy condition, a
fitting subject for the attacks of fungi and aphides.”
Other observers say “it is impossible to over-cultivate any
plant.” In our opinion, this is a mistake, for over-
manuring with the favourite kainit or potash manures
generally has a tendency to favour the development and
growth of Peronospora infestans and similar fungi
(Chemical News, vol. 53, p. 255).

Potato-growers should try to produce by crossing, etc.,
a disease-proof potato. The late Mr. Darwin was greatly
interested in Torbitt’s experiments “of raising fungus-
proof varieties of the potato.” He describes Torbitt’s
method of procedure! in the following words: “It con-
sists of rearing a vast number of seedlings from cross-

1 Life and Letters of Charles Darwin, vol. iii. p. 348.

56 DISEASES OF CROPS.

fertilized parents, exposing them to infection, ruthlessly
destroying all that suffer, saving those which resist best,
and repeating the process in successive seminal genera-
tions. . . . There is no great improbability in a new
variety of potato arising which would resist the fungus
completely, or at least much better than any existing
variety. With respect to the cross-fertilization of two
distinct seedling plants, it has been ascertained that the
offspring thus raised inherit much more vigorous consti-
tutions and generally are more prolific than seedlings
from self-fertilized parents.” (2) Destroy common bitter-
sweet, henbane, and similar plants belonging to the same
natural order as the potato, as Peronospora infestans also
infests these as well as the potato. (3) Burn all infested
haulms of the previous potato crops. (4) When the crops
are first attacked, a good plan is to remove all infested
stems and leaves. (5) “ When cut sets are used at plant-
ing, the cut surface should perhaps be allowed to heal or
dry before planting ; or, if this is not convenient, the cut
surfaces might be quickly passed over a hot iron.” (6)
‘Potatoes should be stored in perfectly dry, airy places,
in positions where light is not entirely excluded. Pota-
toes should never on any account be stored in heaps, or
in the damp holes in the ground termed ‘pies’ ” (Smith).
(7) The “earthing-up” of potatoes has a tendency to
lessen the attacks of Peronospora infestans.

Cure.—(1) The author has shown (Journal Chemical
Society, 1886, p. 119, and Chemical News, vol. 58, p. 255)
that iron sulphate destroys P. infestans, by acting upon
the cellulose walls of the mycelium of this fungus, but
does not injure the cellulose of the host-plants! A good

1 The cellulose of parasitic fungi is most probably an isomeric

ROOT CROPS. 57

method of utilizing the sulphate is to prepare a solution
containing from 1 to 5 per cent. of commercial iron
sulphate, and distribute it by means of a Strawsonizer
at the rate of two gallons an acre. M. Delacharlonny
(Biedermann’s Centralblatt fiir Agricultur-Chemie, vol.
xviii.) has confirmed the author’s investigations, and
states that iron sulphate is best applied when the young
potato plants have reached the height of a few inches.
~(2) Top-dress the land (when the plants are a few inches
above ground) with $-cwt. of iron sulphate mixed with 5
to 10 times its weight of sand or dry earth per acre. The
above dressing destroys the fungus in the early stages of
its life-history. (3) M. Prillieux (Comptes Rendus, vol.
107, p. 447) has used a mixture containing copper sulphate
(blue vitriol) for destroying Peronospora infestans. This
mixture is made “by dissolving in every 10 gallons of
water 6 lbs. of copper sulphate, and then adding 6 lbs. of
slaked lime.” Dr. J. M. H. Munro (Bell’s Weekly Mes-
senger, Feb. 4th, 1889) recommends the above mixture to
be applied by means of the Strawsonizer or pneumatic
distributor.

The Potato Smut (Tubercinia scabies) is a fungus
which confines itself entirely to the tubers of the potato.
It lives between the cuticle (“skin”) and the epidermis
of the tuber, often causing a dark-brown envelope over
the entire potato. This fungus is to be recognised by the
discoloured patches on the cuticle of the tubers. The
greenish-brown spores of Tubercinia scabies are com-
pound, i.e., they are multi-cellular. The cells unite form-

modification of the cellulose found in the higher plants. Hence the
reason of the difference in the action of iron sulphate in the two
cases.

58 DISEASES OF CROPS.

ing a kind of “ head ” with one or more lacune (apertures).
The mature spores rupture the “skin ” of plant potato and
are therefore liberated.

Prevention and Cure.—(1) The seed potatoes should be
free from this disease. (2) Steep the seed potatoes in a
solution containing from 1 to 5 per cent. of iron sulphate.
This will destroy any spores of the potato smut that may
be upon them.

Fusisporium solani (Periola tomentosa, Fig. 24)
is another fungus which attacks potato crops. It makes

Fig. 24.—Fusisporium souani oF Poratozs.
(x 200 diam.)

its appearance chiefly in the autumn, when it is to be
seen upon the potatoes growing in the soils of the south-
ern and midland counties. So far, it has confined its
attacks to these counties, and has not been discovered in
Wales or Scotland. Fusisporiwm solani attacks chiefly
the starch granules of the tuber by sending its mycelium
amongst the cells, and thereby causes putrefaction. The
mycelium, in a few hours, gives rise to conidiophores,
being crescent-shaped compound conidia (spores) (Fig.
24 B). The spores, which are divided by three transverse
septa, separate when mature (Fig. 24 C), forming four
more or less square-ended spores. These subsequently

ROOT CROPS. 59

become round. The spores may germinate immediately
or become spinulose (Fig. 24 A) and hibernate for some
time. The spores give rise to mycelia when circumstances
are favourable for their development and growth.
Prevention.—Burn all infested matter, and plant pota-
toes free from disease.
The Irish (?) Potato Fungus (Peziza postuma,

B

ec
Fig. 25.—Psziza postuma (a potato fungus).

A, The fungus growing from a Sclerotium (2); at lis the pileus or cup-like
head (nat. size).

B. Diagram of upper part of pileus, showing the “ perpendicular cells.”

C. The contents of a “ perpendicular cell.” (1) Ascus containing spores
(sporidia). (2) A paraphysis (x 200). .

D. Stem of potato plant with nodular sclerotia (nat. size).

Fig. 25) was first observed in the West of Ireland in 1880,
and a description of it appeared in the Gardeners’
Chronicle for August 20th, 1880. It produces nodular
growths upon and within the stems and leaves of the
potato plant (Fig. 25 D). Unlike Peronospora, this fun-
gus does not cause putrefactive changes to occur within
the tissues of the host-plant, but extracts the sap, etc.,
of the stems and leaves, which finally become dry and

60 DISEASES OF CROPS.

withered. The nodular growths (of a brownish-black
colour, although white at first) are composed of a compact,
hard mycelium. Each nodule is called a sclerotium, which
is capable of hibernating for a longer or shorter time
according to circumstances. When one of these bodies
grows, it gives rise to a perfect fungus bearing a cup-like
head containing spores (Fig. 25 A). The spores after
germination reproduce the mycelium, which may either
produce spores or become a sclerotium. Fig. 25 A repre-
sents a sclerotium giving rise to hyphe; each hypha
bearing a cup-like head (somewhat similar to the pileus
or cap of the mushroom) containing millions of spores.

If a transverse section of the hymenium, pileus (?), or
cup-like head is examined under the microscope, it is seen
to consist of a number of perpendicular cells (Fig. 25 B).
Each cell contains an ascus (a kind of “ sack ”’) filled with
sporidia! or spores (Fig, 25 C). The paraphysis? (shown
in Fig. 25, C 2) is an “organ” developed from the cells of
the lower part of the hymenium. At certain times the
asci open at the top, and the spores are liberated. It has
been estimated that cach cup-like head contains from two
to three million spores.

Prevention.—(1) Artificial manures are better suited
than farmyard manure for the cultivation of potatoes.
Mr. W. G. Smith, F.L.S., states that “it is bad in practice
to place potato sets in immediate contact with decaying
vegetable matter and farmyard manure; such materials
always contain an immense number of disease germs, both
of animal and vegetable origin. The manures used for
potatoes should always be old and thoroughly decayed,
and it is perhaps best that the cut faces of the sets should

‘ Sporidia are spores free in an ascus. 2 Its function is unknown.

ROOT CROPS. 61

be allowed to dry before they are planted.” We can
thoroughly recommend the following “ mixed” manure for
the growth of potatoes :—

£ os. da.

1 ewt. kainit : » 0 2 0

Per )1 ,, nitrate of soda . - 0 910
Acre. }4 ,, iron sulphate : - 01 38
2 ,, mineral superphosphate 05 0

£018 1

The ingredients to be thoroughly mixed together, and
applied after setting the seed potatoes (See the author’s
Treatise on Manures, or Manures and their Uses). (2)

Fig. 26.—Turnie “Fry” (Haltica nemorum).
A. Beetle (nat. size).
B. Beetle (enlarged),
C. Masses of eggs (nat. size).
Burn all infested haulms, as this destroys any hibernating
sclerotia, etc.

(7) Tue PaRrasITes or Turnips (Brassica rapa).

The Turnip Fly (Haltica nemorum, Phylletreta
nemorum, or ‘ turnip flea,” Fig. 26) belongs to the Halti-
cide, a family of small beetles. They are oval insects,
often measuring less than one-twelfth of an inch in length,

62 DISEASES OF CROPS.

and have thickened femora (thighs) which enable them
to leap almost like fleas. The species under consideration
is black with a yellow stripe on each wing-sheath, and is
very destructive to turnips. ‘“ The eggs are laid upon the
underside of the rough leaf from June to September, and
hatch in seven or eight days’ time.” The white larvae
(whose heads are provided with cutting jaws) live between
the cuticles of the leaf, and in about six or seven days
turn to pup, which bury themselves in the ground. In
about fourteen days the perfect insects appear. They
live through the winter in a torpid state (under bark,
clods of earth, and in manure heaps), reviving in the
spring. The spring is the period of special danger, for
these beetles most seriously injure the cotyledons or seed-
leaves of the young turnip plant. ‘Many a farmer has
seen a promising braird one evening, but not a vestige of
green leaf has been visible on the day following. Unfor-
tunately, the insect is able to travel miles, even against
the wind, to wreck a crop of turnips.” There are several
other species of the Haltica (besides the one described)
which feed upon the leaves of the turnip, and often par-
tially or wholly ruin field after field of this crop. The
Halticee have several broods in a season.

Prevention.—(1) Destroy charlock, shepherd’s purse,
and other cruciferous weeds, for the Halticew feed upon
these plants as well as upon turnips: (2) “Manure
liberally, and obtain a firm and thoroughly fine seed-bed.
Beware of clods! Sow the best new seed, and always use
the drill instead of broadcasting.” (3) Use artificial fer-
tilizers in preference to farmyard manure, unless the latter
can be deeply buried. (4) Artificial fertilizers should be
deposited along the ridges as soon as the latter are made.
They not only give vigour to the plants in their early

ROOT CROPS. 63

stages, when the insects commit so much damage, but they
ward off the “ flies,” being objectionable to them.
Cure.—(1) “ Roll and lightly harrow after 8 p.m. and
before 6 a.m., for this disturbs and weakens the ‘ fly,’ and
stimulates the young plant. Sow eight bushels per acre

Fig. 27.—Turnip Apuis (Aphis floris-rape).

“A. Male with closed wings (enlarged).

B. Its natural size.

C. Wingless female (enlarged).

D, Its natural size.

EB. Flask-shaped abdomen of Aphis rape.
of fresh-slaked lime along the rows just as the plants are
appearing.” (2) ‘‘ Dustings of fine ashes or soot are also
effectual, but salt must not be used, for it injures the
plant and does not hurt the beetle.” Dressings should
always be applied whilst the dew is on the plants. (3)
Mr. W. G. Mount, M.P., has eradicated the turnip fly with
either lime or paraffin distributed by means of a Strawso-
nizer (see Miss Ormerod’s Common Farm Pests).

The Turnip Aphis or Green Fly (Aphis floris-

rape and Aphis rape, Fig. 27) is allied to the bean aphis

64 DISEASES OF CROPS.

already described. The Aphide, or plant-lice, are an ex-
cessively injurious family of Homopterous insects, Every
farmer, every rose cultivator, every hop-grower has too
great reason to be well acquainted with these destructive
pests. The species are very numerous, almost every plant
having its own peculiar parasite; they attack the leaves,
stems, shoots, and even the roots of plants, piercing with
their sharp proboscis the cuticles and sucking the juices.
Aphis rape is chiefly found on the under surfaces of
turnip leaves. The wingless female (viviparous) is green,
but becomes a yellowish-red colour later in the season.
The head and thorax of the winged female are black,
whilst the abdomen and wings are of a yellow colour.
The posterior part of the abdomen of this species is flask-
shaped (Fig. 27 E). According to Curtis, the variety
known as Aphis floris-rape: (Fig. 27 A and C) is found on
the flower-stalks. Aphis rape “ multiplies with amazing
rapidity under favourable atmospheric conditions.”

The great enemies of the Aphida are the so-called
“lady-birds”—small beetles belonging to the Cocci-
nellide. The French call these insects ‘“ Béte de la
Vierge”’ and “ Vache 4 Dieu.” The Germans call them
“Marienkifer,” ‘ Marienkuh,”’ and ‘ Gotteslammchen.”’
The majority of these insects are undoubtedly the friends
of the farmer, and their presence upon all cultivated plants
is most beneficial. The ‘‘ common,” or seven-spotted lady-
bird (Coccinella septempunctata), and the two-spotted
lady-bird (C. bipwnctata) are common species. “ They lay
their eggs in small patches in the midst of the Aphides
which are destined to furnish nourishment to the larve.”

Prevention and Cure.—(1) “Nearly all the remedies
proposed for the extermination of Aphis rape consist of
water containing some poisonous infusion, such as tobacco,

ROOT CROPS. 65

quassia, ammonia, etc. On a large scale the application is
costly ; and although it may pay for a crop of hops, it has
hitherto been impracticable for roots,” (2) “When the
turnips are attacked near maturity, the folding of sheep
destroys the insects, and may prevent their reappearance
in the following season.”

The Turnip Gall Weevil (Ceutorhynchus sulct-
collis, Fig. 28) belongs to a group of beetles called the

Fig. 28.—Tournie Gatun Weevin (Ceutorhynchus sulcicollis).

A. Gall-like excrescences on turnip-bulbs.

B. A gall with grub inside (nat. size).

C. Turnip Gall Weevil (enlarged).
Rhynchophora, whose snouts, as a rule, are very long.
The antenne are placed on each side (of snout), “elbowed”
or angulated in the middle and elubbed at the extremity.
The female turnip gall weevil punctures the “ roots,” and.
deposits an egg in the wound. Within this domicile the
yellowish-coloured larva or maggot lives, feeds, and attains
its maturity. This beetle (Fig 28 C) is most injurious to

F

66 DISEASES OF CROPS.

swedes and turnips. The larve cause gall-like excres-
cences (Fig. 28 A) to grow upon the surfaces of turnip
“yoots.”” When the larve have attained maturity, they
are provided with powerful jaws, which are used for gnaw-
ing a way out of their temporary abode. The larve turn
to pup in the soil, where they remain about twenty-eight
days, enclosed in “ earth-cases.” The perfect insect is of
a blackish hue, and the elytra are marked with a number
of stripes and dots.

This weevil greatly reduces the quality of the roots, as
the following analyses show :—

ANALYSIS OF TuRNIP Roots.!

Uninjured | Injured
Roots. Roots.

Albuminoids (flesh formers) Z 9°86 710

Dried |Soluble carbohydrates and fat eae
solid producers) . . ‘ 71°90 | 62:02
matter. | Woody fibre a i 3 é F 11:24 23°25
Ash . . a a 7:00 7°63

The above table shows that the injured roots contain
smaller percentages of albuminoids and soluble carbo-
hydrates than the uninjured roots.

It is stated that, in both the larval and pupal stages,
this weevil is capable of enduring a temperature many
degrees below the freezing-point of water.

Prevention.—(1) “ Regular rotation of crops, generous
and clean cultivation, and the free use of lime or gas-lime,
will prevent this weevil from doing much harm.” (2)
“Galled portions of roots which are left by sheep should
be burned.”

1 Dr. A. B, Griffiths’ analyses.

ROOT CROPS. 67

The Harvest Bug (Tetranychus autumnalis) be-
longs to the Arachnoidea, and for several reasons the
members of this class are looked upon as modified insects.
The so-called “harvest bug” is a spinning mite, and on
the authority of M. Megnin (L’Insectologie Agricole)
possibly injures the leaves of turnips as well as those of
grass and corn crops.

According to Curtis, another arachnoid (Trombidium
trigonunt) injures the spikes of corn, especially in France.

The Turnip Leaf Miners (Drosophila flava and
Phytomyza nigricornis) are the larve of two dipterous
flies which feed upon the parenchyma (soft parts) of tur-
nip leaves. D. flava is about one-tenth of an inch long, of
a yellow colour. The larve of this two-winged fly are
of a green colour, and live beneath the cuticle on the
upper side of the leaves. P. nigricornis is the same size
as the “yellow leaf miner,” but has a black body and
slate-coloured wings. The larve burrow beneath the
cuticle on the under side of turnip leaves, and there feed
upon the soft parts. The pups of both insects are brown
in colour, and, as a rule, the larve turn to the pupal stage
within the leaves.

Prevention.—Burn all infested leaves.

The Turnip Moths (Plusia gamma, Cerostoma
xylostella, Noctua |Agrotis] eaclamationis, and Noctua
[Agrotis] segetum) are four in number, and their methods
of attack are somewhat dissimilar. (a) The Silver Y Moth
(Plusia gamma) has already been described. (8) The
Diamond-back Moth (C. aylostella) “seldom does much
damage.” The green-coloured larve feed on the foliage
of turnips and swedes. They are about half an inch long,
and taper towards both ends. When mature, the cater-
pillars spin light cocoons between the veins of the leaves

68 DISEASES OF CROPS.

—the latter having been stripped of the intermediate soft
tissues. Within the cocoons the caterpillars turn to
pupe, which are of a grey colour with black markings.
The pup give rise to perfect insects in about fourteen
days. The moth is somewhat similar in appearance to
the ordinary clothes-moth. Along the anterior edge,
the fore wings are brown, while the posterior edge is
white. The hind wings are deeply fringed. (y) The
larve of the Heart and Dart Moth (N. exclamationis)
also feed on the foliage of turnip crops. They attack the
plants during the night, while in the daytime they hide
beneath stones, clods of earth, etc. The larve of this
moth are about 13 inch long, of a pale violet colour, with
a brown head. When fully grown they make earth-
cells, and there turn to pupe. The latter are of a
reddish-brown colour, and hibernate (in their cells) until
the following season. The moth is of an ochre colour,
with a black spot situated posteriorly to the head. The
anterior wings of both the male and female are brown,
with darker coloured nervures. The posterior wings of
the male are white, while those of the female are brown.
(8) The larve of the Turnip Moth (N. segetum) feed on
turnips and other roots by gnawing their way into the
“roots.” They also feed on the leaves of the turnip
plants. These larvee (which are nocturnal in their habits)
are about one inch long, almost hairless, and feed not only
during the summer and autumn, but also in the winter
if circumstances are favourable. If not, they pass the
winter in earth-made cells. In the following spring they
turn to brown-coloured pup in the ground, where they
remain for twenty-eight days, changing in that time to
moths. The male moth has grey-coloured fore and white
hind wings. The colour of the thorax and abdomen ig

ROOT CROPS. 69

also grey. The fore wings, thorax, and abdomen of the
female are brown, while the hind wings are white.

Prevention.—(1) “Generous culture, clean boundaries,
strong-growing seeds will keep down the ‘ turnip moths.’”
(2) The rook, partridge, jackdaw, raven, chiff-chaff, mag-
pie, blue-tit, redstart, and crow, all destroy the larve of
these and similar farm pests.

Cure.—Gas-lime, tobacco-water, lime, soot, and hand-

Fig. 29.—Turnip Saw-Fry (Athalia spinarum).

A. Turnip Saw-Fly (enlarged slightly).
B. Larve feeding upon turnip leaf.
C. A portion of the saw-like organ.

picking are remedies not difficult to apply ; although they
add to the cost of cultivating turnip crops.

The Turnip Saw-Fly (Athalia spinarum, Fig. 29)
belongs to a family of insects distinguished by the peculiar

70 DISEASES OF CROPS.

construction of the ovipositor,| which has procured for
them the name of “saw-flies.” This organ (Fig. 29 C),
which is to be found on the posterior-ventral side of the
perfect insect, is composed of a pair of broad, serrated
plates, the analogues of the inferior bristles of the bee’s
sting. By the agency of this curious organ, the female
cuts numerous minute slits in the leaves of the turnip
plants, in each of which she lays an egg. It is said that
each female lays from two to three hundred eggs during a
season. The eggs are hatched in from four to ten days. ©
The larvee (Fig. 29 B) (called “ niggers,” “ blacks,” “ black
caterpillars,” etc.) feed upon the leaves of turnips, which
_they reduce to mere skeletons of fibres, and sometimes
cause the complete destruction of the crops over a con-
siderable extent of country. The young larve are of a
green colour, but ultimately turn black. “The larva of
A. spinarum is large at the head tapering to the posterior,
and possesses a remarkable structure in its feet, some of
which are hooked, and others act as suckers.” In about
three weeks after birth these caterpillars retire to the
ground, where they spin cocoons in which they turn to
the pupal stage. During the early summer the pupe are
transformed into perfect insects in about twenty-one days,
but if late in the season the larve remain in the cocoons
throughout the winter, turning to pupe in the following
spring. There are several broods in a season. The per-
fect insect (Fig. 29 A) is a pretty black and yellow fly,
with short antenne, and is common in the fields during
the summer. According to the late Mr. Curtis, these flies
come over from the North of Europe, but are probably bred
in small numbers annually in this country.

1 An organ which aids in the laying of eggs.

ROOT CROPS. var

Prevention.—(1) As “the caterpillars are found in
swarms, drawing bushes over the plants disturbs and dis-
tributes them advantageously.” Then throw lime or lime
and soot over the plants—this “ will do something towards
protection.” (2) “A thick sowing of good seed will gene-
rally be found to have insured sufficient plants for a crop.”

Fig. 80.—Surracz Fonavus or Turnips (Oidium Balsamii).

BO. Lower and upper surfaces respectively of a turnip leaf,
AD. Mycelia (spawn) on both surfaces.
E. Stomata. HF. Conidia (spores). x 196,

(3) Watering the plants (by means of a water-cart) is
beneficial to the crops and prejudicial to the insects,

The Surface Mould of Turnips (Oidium Bal-
samit, Fig. 80) is a fungus which attacks turnips (especi-

72 DISEASES OF CROPS.

ally swedes) chiefly in the South of England. So far, it
has not been found in Scotland; most probably because it
requires a higher mean temperature than occurs in North
Britain. This mildew or mould does not enter the tissues
of the host-plant, but lives upon the two external surfaces
of the leaves. When a crop of turnips is attacked by
Oidium Balsamit, the foliage appears white on both sides.
The mycelium (Fig. 830 A and D) spreads over the cuticle
of the leaves; and gives rise to perpendicular conidio-
phores bearing elongated, square-ended conidia or spores
(Fig. 30 F). It has been estimated that there are more than
10,000 spores on every square inch of the infested leaves.
The conidia of this fungus germinate readily, and give
rise to mycelia.

As the fungus covers both sides of the turnip leaves,
it greatly interferes with the processes of assimilation
and transpiration ; and thereby prevents further growth.
This causes a low yield of roots. The further life-history
of this fungus is unknown.

Cure.—Possibly a solution of iron sulphate or copper
sulphate would destroy this fungus (see the “ cures” for the
potato disease).

The Turnip Mould (Peronospora parasitica), which
belongs to the same genus as the potato-disease fungus,
will be described under the head of “The Parasites of
Cabbages,” as it attacks these plants as well as turnips.

Finger-and-Toe, Anbury, or Clubbing of Tur-
nips (Plasmodiophora brassicw, Fig. 31). Every farmer
knows that turnip and other root crops are liable to
degenerate through the abnormal growth of nodules or
knobs+ upon the tubers, roots, and rootlets. Turnips so

1 See the author’s book: Manures and their Uses, p. 40.

ROOT CROPS. 3

affected soon rot, and have a, fostid odour, so that they are
not only useless themselves, but communicate the disease
more or less to the whole crop. The cause of “ clubbing ”
was proved by M. Woronin in 1876 to be due to a slime
fungus belonging to the Myxomycetes. “The Myxomy-
cetes are especially remarkable, from the fact that they do
not form cells, cell-walls, ‘tissues’ or mycelium, during
the period of vegetation; but their protoplasm remains
during that time free, and collected into small masses
of various and changeable forms. At a certain definite

Fig. 31.—‘ Finarr-anp-Tor” or Turnips (Plasmodiophora brassice).
1. panera section of turnip root, showing the ** plasma ’”’ (B) 3 the fungus.
Normal size of cell. B. Gell distended by fungus (x 100).

= Beare prodnced from plasma (x 195).
. Spores giving rise to zodspores (a) (x 490).

advanced period of growth the vital material of a Mymo-
mycete breaks up into small portions, and these portions
at length surround themselves with a cell-wall, and
become either fruits, sporangia, or spores; and in this
condition the fungus remains at rest during a certain
definite period.” This is essentially different from the
life-history of Peronospora infestans or any other fungus
previously described.

74 DISEASES OF CROPS.

The spores of the club-root fungus generally commence
the attack in turnip seedlings; by entering the rootlets
with water in an attenuated form. As growth proceeds,
the turnip plants become diseased, the foliage droops, and
the roots are stunted in growth. If during the summer
a thin transverse section of one of the nodular out-growths
is examined under the microscope, a large number of cells
will be found filled, or nearly filled, with the slime or
plasma of this fungus (Fig. 31, 1). This slime greatly
distends the cells of the turnip, and thereby causes the
nodular outgrowths upon the roots, known as ‘“ clubbing.”
There are no hyphe.

As the fungus increases in size, the nodules also increase.
In the autumn the slime or plasma breaks up into number-
less small spores (Fig. 31, 2), which are surrounded by
cell-walls. The spores rest during the winter in the
turnip roots. In the following spring (if circumstances
are favourable) the spores germinate, when little jelly-
like masses exude from them (Fig. 31, 3). Each little
mass is called a zodspore, and is provided with a cilium (a
“vibrating tail’), which enables it to move over moist sur-
faces. The zodspores of P. brassice are always changing
their shapes—hence they are somewhat similar to certain
low forms (Amebee) belonging to the animal kingdom.
The zodspores of the club-root fungus (like certain of the
Monera 1) quickly coalesce and form what is known as a
plasmodium—hence the generic name of the fungus. If
infested and rotten turnip roots have been previously
thrown on manure heaps, and the manure then distributed
over the land, the plasmodia are liberated by rain or the
moisture of the soil, and are then ready to commence the

1 See Haéckel’s Studien iiber Moneren.

ROOT CROPS. 75

work of destruction in any young turnip, cabbage, or other
cruciferous crop near at hand.

The following analyses (by the author) show the changes
which occur within turnip roots during the early stages
of the growth of Plasmodiophora brassice :—

Albuminoids in healthy roots . . . . . . « 9°92 per cent.
8 diseased ,, (minus nodules). . 5:23 a
ve nodules (with fungi). . . . . 1861 9

The above analyses show that the growth of the fungus
lessens the percentages of albuminoids or nitrogenous
substances in the roots. As Plasmodiophora (like all
fungi) cannot “ manufacture” albumin and requires it—it
extracts this life-giving substance from the living cells of
the host-plant.

Prevention.—(1) Do not allow the cruciferous weeds,
more than is possible, to choke the hedge-sides of the fields
and ditches under cultivation. (2) As the spores of this
fungus retain their vitality for several years under favour-
able circumstances, when land has borne an infested crop,
the best thing to do is to remove decaying roots, stumps,
etc.,and burn them. (3) Rotation of crops, i.e., allow two
or three years to elapse before again sowing cabbages, tur-
nips, or other root crops. (4) Whenever possible, avoid
working the land in a wet condition. (5) The selection
of good seed! and the most approved methods of culture
are means of preventing this disease.

Cure.—After clearing the land, give it a good dressing
of gas-lime or lime and soot.

This chapter surveys the life-histories of parasites

1 Turnip seeds have often been adulterated with charlock, ‘‘ Indian
rape,” and other seeds of the Brassicacee.

76 . DISEASES OF CROPS.

which infest root crops. Some belong to the animal,
others to the vegetable kingdom. Every cultivated plant
has its own foes; but whether we look upon them as
enemies or not, they have all come into the world for the
same object as the rest of animated nature—namely, to
live, reproduce, and die—so the world goes on! They
are, therefore, part and parcel of the organic world and
not isolated from it. In the words of Carlyle:! “ De-
tached, separated! I say there is no such separation:
nothing hitherto was ever stranded, cast aside; but all,
were it only a withered leaf, works together with all; is
borne forward on the bottomless, shoreless flood of Action,
and lives through perpetual metamorphoses.
Rightly viewed, no meanest object is insignificant; all
objects are as windows, through which the philosophic
eye looks into Infinitude itself.”

1 Sartor Resartus, chap. xi.

CHAPTER IV.

THE DISEASES OF GRAMINEOUS CROPS.

(1) Tse Parasites oF Baruey (Hordeum distichum).

The Grain Aphis (Aphis granaria, Siphonophora
granaria) is about the same size and somewhat like the
bean aphis already described. The abdomen of the winged
female is green, the thorax and head brown, and the
wings green with brown veins. The wingless female
(viviparous) has a greenish coloured body with brown
antenne, and the legs are devoidof hairs. Both the wing-
less and winged females have red eyes. The pupe are
of a chrome-yellow colour and the larve green. A.
granaria injures oats, rye, and wheat, as well as barley,
by sucking the juices from the young stems and leaves of
these crops. Later in the season, this insect attacks the
ears of corn (when the grain is green), and often causes
considerable damage. On the authority of Mr. Walker,
Aphis granaria passes the winter on “‘ certain grasses.”

Prevention. —(1) The Grain Aphis has two parasitic
foes, namely—Ephedrus plagiator and Aphidius avene—
two flies (about the same size as Aphis granaria) belong-
ing to the Ichnewmonide. These flies pierce the bodies
of the aphides with their sharp ovipositors and lay an egg
in each newly-made cavity. The eggs soon turn to larve
which feed on the aphides. These parasitic flies remain

within the bodies of the aphides during the pupal stage,
7

7 DISEASES OF CROPS.

and, when they turn to perfect insects, they eat their way
out of the now dried and puffed-out skins of the aphides.
(2) Another enemy of this and other aphides is the blue-
tit (Parus cwruleus). This little bird and the titmice
generally are without doubt the friends of the farmer.
Mr. W. Swaysland (Familiar Wild Birds) says: “The
number of obnoxious pests destroyed in one day by a
blac-tit must be very considerable, and it is to be re-
gretted that due importance is so seldom attached to this
fact by gardeners and other individuals who wage war
against it, merely regarding it as a nuisance and a de-
predator.” (38) Good cultivation and a liberal supply of
manure (artificial as well as natural) are means of pre-
venting the attacks of this pest.

Cure.—Dressings of lime, soot, or soot and lime, whilst
the crop is young, are means of destroying Aphis granaria.

The Ribbon-footed Corn Fly (Chlorops teniopus,
Fig. 32)! attacks barley and wheat crops, but more par-
ticularly the former. “ Plants affected by Chlorops are
easily detected. Generally, the ears are not free as
healthy ears, but are enwrapped still in the sheathing
leaves. Little yellow maggots may be found near the
nascent ears, sucking out the juices of the plant. When
these injured ears get out of their sheath, or are stripped
of their sheath when the plants are ripening, a destructive
furrow is seen from the base of the ear to the internode
(Fig. 32 D). In this furrow the larva changes to a pupa.”
Affected plants are shorter than healthy ones, “ their
stems are stouter and the joints are frequently swollen,
or ‘ gouty’ in fact.”

The fly (Fig. 32 A) is of a yellow colour with brown

1 « Gout fly,” “‘ Haulm fly,” ete.

GRAMINEOUS CROPS. 79

markings on the dorsal side of the thorax and abdomen.
The six legs are yellow with black tarsi (feet). The
perfect insect makes its appearance usually in May. The
female lays eggs (white) near the base of the sheathing
leaves of barley plants. The eggs are hatched in four
or five days, when the yellow, legless maggots pierce a

Fig. 32.—Rippon-rootep Corn Fuiy (Chlorops teniopus).

A. The fly (enlarged), | C. Larva (nat. size).
B. Its natural size. D. Infested stem.
E. D. enlarged.

way into the young ears of corn, and feed there by ex-
tracting the sap, etc., of the host-plants. ‘The larva
always makes a furrow from the base of the ear to the
first joint or knot of the stem. In this furrow the change
from the larval to the pupal stage takes place.” Accord-
ing to Dr. Taschenberg! the larvee of Chlorops hibernate

! See his Praktische Insekten-Kunde and his various memoirs.

80 DISEASES OF CROPS.

in the leaves and stems of grasses. The pup of this
insect are of an ochre colour. Cthlorops has several foes
belonging to the Insecta ; the most important of which
are Pteromalus micans and Celinius niger—two flies
which lay eggs within the bodies of the maggots of
Chlorops teniopus. The larve produced from these eggs
feed and live upon the maggots of Chlorops, reducing
them to mere empty skins.

It has been estimated that this fly caused a loss of from
3 to 14 bushels of corn per acre (Whitehead’s “Reports ”).

Fig. 33.—Tur Corn Saw-Fiy (Cephus pygmaeus).

A. The fly (nat. size).
B. Larva (nat. size).
C. Infested stem (enlarged).

Prevention.—(1) Grasses, etc., infested with Chlorops
should be eaten by sheep. (2) After thrashing infested
barley or wheat, the chaff, etc., should be burnt. (3)
Pulling up all stunted and infested plants has a tendency
to greatly reduce the attacks of this pest. (4) Promote
healthy and vigorous growth by the judicious use of

soluble manures; for barley is a “shallow feeder ” (i.e.,
it obtains nourishment from the surface soil), and requires
easily assimilable plant-foods.

The Corn Saw-Fly (Cephus pygmeus, Fig. 33)
belongs to the Hymenoptera, and attacks barley and other

GRAMINEOUS CROPS. 81

corn crops. The female pierces, by means of its saw-like
ovipositor, a hole in the young corn stem, and lays an
egg therein. The white larva or maggot (Fig. 33 B and
C), which is hatched in about ten days, feeds on the sap
and soft tissues in the interior of the stems of the barley
or wheat plants, causing great injury. The larve are
provided with powerful jaws, capable of cutting furrows
in the stem of the host-plant. The larve ultimately spin
silken cocoons, in which they hibernate in the stems of
the stubble. In the following spring they turn to pupe,
making their appearance as perfect insects about May.
The perfect insect has four wings which are iridescent.
The body is black with yellow markings. ‘From ten
to a dozen eggs are laid by each female, and are deposited
singly in the stems of the corn plants not far from where
the ears are forming, whose situation is divined with
wonderful instinct.”

Prevention. — (1) Plough in deeply all infested stub-
bles. (2) “Scarifying, or cultivating, the land and
burning the stubble harrowed together would also be
useful, though not so sure as ploughing it in.”

Cure.—All infested lands, after ploughing in the stubble,
should be treated with quicklime, salt, or gas-lime, for
these substances destroy the larve of this farm pest.

The Fusisporium of Barley (Fusisporium hordet,
Fig. 34) attacks the ears of barley. The infested grains
of barley become covered with orange or scarlet-coloured
mycelium and conidia of this fungoid growth. The
fungus is allied to another species of the same genus,
viz., F. solani (already described). The crescent-shaped
spores ultimately separate and become globular conidia,
which rest for a short time, but finally give rise to new
mycelia. The fungus obtains nourishment from the entire

&

82 DISEASES OF CROPS.

grain (embryo, cotyledon, and husk),—but particularly the
embryo or germ,—and thereby destroys the germinating
power of the grain (either for seed or for malting pur-
poses). It has been stated that the conidia of this fungus,
when introduced into beer-wort (previously sterilized),
give rise to a slow alcoholic fermentation, as well as
producing a badly flavoured beer.

Fig. 34.—Tar Fostsrorium or Bartzy (Fusisporium hordei).
A. An ear of barley infested with the fungus.

B. Barleycorn (infested),
C. Thefungus. x 320 diameters.

The name Fusisporium hordet was given to this fungus
by Mr. W. G. Smith, F.L.S., who, with other fungologists,
investigated its life-history.

1 The author has shown that most of the so-called “ false beer fer-
ments ” are destroyed by the action of a solution of salicylic acid (see
Proceedings Royal Society of Edinburgh, vol. xiii. p. 527; The Brewers’
Guardian, vol. xvi. p. 21; and Journ. Chem. Soc., 1886, p. 386).

GRAMINEOUS CROPS. 83

Prevention.—Sow only new and sound barley.

Cure.—(1) Steep the seed, for two or three hours before
sowing, in a solution of iron sulphate (1 to 2 per cent.
solution). (2) Copper sulphate is recommended for “ pick-
ling” the seeds of various cereals before drilling; but.
this substance often destroys the germinating power of
seeds (vide Biedermann’s Centralblatt fiir Agricultur-
Chemie, 1886, p. 766).

The Smut of Barley (Ustilago carbo) and other
cereals will be described under ‘The Parasites of Oats.”

(2) THE PaRASITES OF BUCKWHEAT (Polygonum
fagopyrum).}

According to Alphonse De Candolle, buckwheat is pro-
bably an Asiatic plant. ‘In China the seed is used for
making bread, and in Europe it, is employed for various
culinary purposes.” In England it is principally sown to
produce a covert and food for game. On the Continent
(and also to a minor extent in England) buckwheat is used
as a green manure. The gaseous products of its decom-
position destroy various injurious insects.

The Buckwheat Eelworm (Tylenchus Haven-
steiniz) belongs to the same genus as the clover eelworm,
already described. It is a nematoid, and measures
1:43 mm. x 0:0301 mm.? These thread-worms attack the
roots and stems of the host-plant.

Cure.—Drs. Kiihn and Oehmichen recommend liberal
manuring, especially with kainit.

The Buckwheat Beetle (Phyllopertha horticola)

1 Buckwheat belongs to the Polygonacee (dock and sorrel order).
It is not a gramineous crop, although described under that heading.
2 1 millimetre (mm.) =0-03937 inch.

84 DISEASES OF CROPS.

is asmall cockchafer belonging to the family Rutelide.
This beetle measures less than half an inch in length, and
is a bluish-green colour, with reddish-brown wing-cases
(elytra). The larvae feed on the flowers of buckwheat,
causing considerable damage to the grain. The ravages
of this beetle are chiefly confined to Germany and other
parts of the Continent. For further information the reader
is referred to Dr. Calwer’s Kéferbuch, or Taschenberg’s
Praktische Insekten-kunde.

(3) THE Parasites or GRASSES.

The Grain Aphis (Aphis granaria) has already
been described.

The Crane Fly, or Daddy Long-legs (Tipula
oleracea), belongs to the Tipulidw. The proboscis of
the crane fly is very short, terminating by a pair of
fleshy lips which enclose two bristles. ‘In the larval
condition, the crane flies are fearful pests, living just
below the surface of the ground, and feeding on the roots
of grasses. Whole acres of grass have been destroyed
by these larve” (Wood). The larve, or grubs, known
as ‘‘leather-jackets,” are of a brownish colour, and
measure 14 inches when fully grown. They are devoid
of legs, but move by wriggling along, somewhat after
the fashion of the earthworm. The larve of Tipula are
injurious to cabbages, beans, lettuces, and corn crops,
as well as grasses. The pupe appear from July to Sep-
tember, at which time hundreds or thousands of empty
cases “ may often be seen protruding half-way out of the
earth amongst grass, and by the sides of gravel walks.”
The female fly lays eggs during the autumn in or on the
ground, and on damp grass. The eggs are oval, black
grains,

GRAMINEOUS CROPS. 85

Prevention.—(1) Good cultivation and liberal manuring
to produce healthy and vigorous crops. For suitable
manures (for various: grass lands), see the author’s book,
Manures and their Uses, p. 42. (2) A thorough drain-
age of damp (and in fact all) lands has a tendency to
lessen the attacks of this pest. (3) The “brush-harrow”
is useful for preventing the deposition of eggs. (4) Star-
lings and rooks destroy large numbers of the larve of
Tipula. “Perhaps there is no bird that does so much
real good to the husbandman as the starling (Sturnus
vulgaris), for it feeds upon the most destructive grubs
and insects that exist; and therefore this more than com-
pensates for the cherries and elderberries which it eats”
(Swaysland). (5) In the case of old pastures, deep
ploughing buries the larve and eggs, and thereby destroys
them. (6) Rolling infested grass lands (at night) with
a Crosskill or Cambridge roller destroys thousands of
grubs.

Cure.—(1) Dressings of quicklime or gas-lime have
proved useful. (2) Mr. A. Smetham, F.C.S., has shown
that “a solution of sulphate of copper (blue vitrol) killed
the grubs in about eight to twelve minutes. Sulphate of
iron (green vitrol) was more rapid in its effects.” (3)
Salt has been spoken of by some writers; but it has been
shown that ‘the larve of Tipuwla are not killed after an
immersion in strong brine for twenty-four or thirty-six
hours. This is due to their thick and very tough integu-
ments.

The Eelworm of Grasses (Tylenchus devasta-
trix) has already been described. It attacks certain
meadow grasses. Amongst these are the following: An-
thoxanthum odoratum (sweet vernal grass), Poa trivialis
(rough stalked meadow grass), Poa nemoralis (wood

86 DISEASES OF CROPS.

meadow grass), Holcus lanatus (Yorkshire fog, or woolly
soft grass), etc. There is little doubt that this species of
Tylenchus causes considerable damage to grasses, as well
as other farm crops.

The Grass Weevil (Rhynchites bacchus) belongs
to the Rhynchophora, one of the most extensive, as well
as one of the most destructive, groups of the Coleoptera
(beetles). Various members of this group do immense
damage to trees, fruits, grains, etc. For instance, the
corn weevil does much mischief in granaries; the nut
weevil eats a hole in the soft nut, in which it deposits
an egg, which, turning to a larva, eats the kernel, and
leaves only the bitter, dusty contents; the pea and bean
weevils (already described), which spoil the prospects of
the usual accompaniment of roast ducks, all belong to
what are known as the long-nosed Rhynchophora. The
smal] grass weevil (Rhynchites bacchus) is a mischievous
insect in the meadows and pastures of France and Ger-
many rather than in this country. Although a farm pest,
especially in the green pastures of Normandy, it is prin-
cipally one of the chief enemies of the vine. In the
words of the late Rev. J. G. Wood, M.A., “the grass
weevil commits terrible devastations among the growing
vines, sometimes stripping the bushes of their leaves,
which it rolls up and lines with silk.”

The Cockchafer (Melolontha vulgaris, Fig. 35) is
so familiar an object, that it hardly needs description here.
The white or cream-coloured larve of this beetle feed upon
the roots of grasses and other plants, “ and when in great
numbers have been known to ruin an entire harvest. To
turf they are especially destructive, shearing away the
roots with their scissor-like jaws, and killing the vegeta-
tion so effectually that the turf withers, turns yellow, then

GRAMINEOUS CROPS. 87

brown, and can be taken up and rolled by hand.”! The
larva of this insect is an exceedingly fat grub, about an
inch and a half in length, and the thickness of one’s little
finger. It is provided with strong jaws, six jointed legs,
and occasions considerable damage to grass lands during
the three years it remains in the larval form. In the
summer of the third year the grub burrows to a depth of
three to four feet below ground; and in this retreat it
makes a sort of cocoon formed of particles of the surround-
ing materials, agglutinated together by a sticky secretion.
Within this cocoon the larva turns to the pupal stage,

Fig. 35.—Cocscuarer (Uelolontha vulgaris).

finally changing to a perfect insect during the summer of
the fourth year. The beetle (which feeds on the leaves
of the vine, as well as those of the elm, oak, and other
trees) ig about one inch in length, of a blackish-brown
colour. The abdomen has white stripes and ends in a tip
(curved ventrally), which projects beyond the elytra (Fig.
35). The antennez are terminated by clubs composed of
‘seven leaf-like joints in the male, and six in the female.
“Tn their perfect state the cockchafers only live about a
week, and during this time they frequent trees, and feed
upon the leaves. The female, however, when ready to

1 Wood's Illustrated Natural History, vol. iii. p. 467.

88 DISEASES OF CROPS.

deposit her eggs, burrows down into the earth to a depth
of about six inches, where she leaves them; and in the
course of about a fortnight the young larve are hatched,
and proceed in search of nourishment.”

Prevention.—(1) Hand-picking would help to a certain
extent in keeping down this pest. (2) Pigs, ducks, and
poultry readily devour the grubs, as well as the beetles.
(3) Starlings, rooks, crows, nightjars, redstarts, and other
insectivorous birds make “ sad havoc” amongst these farm
pests; therefore they should be protected from injury. It
is most probable that the wholesale destruction of in-
jurious insects by birds! more than compensates for the
small amount of damage the latter may do to various crops
and fruits.

Cure.—Dressings of quicklime, gas-lime, and drench-
ings of ammoniacal or gas-liquor (diluted with four or five
times its bulk of water) destroy large numbers of the
larvee of the cockchafer. The liquor can easily be applied
by means of a water-cart. ‘In very dry weather gas-
liquor ‘burns up the grass,’ but on the first appearance
of rain the herbage will again spring up with increased
luxuriance ” (Treatise on Manures).

The Click Beetles (Elater sputator, Elater ob-
scurus, Elater sanguineus, Elater lineatus, Fig. 36) belong
to the Elateride, and “may readily be known by the
hinder angles of the thorax being pointed, and also by
their power of Jumping up, with a slight clicking noise,
when laid on the back. Most of the species are black, or
bronzed, or partly black and partly yellow. E. sanguineus
(Fig. 36 C) is a bright-scarlet insect, with a black head

1 « Tnsectivorous birds appear to have an instinctive knowledge of
the position of the larva below the surface.”

GRAMINEOUS CROPS. 89

and thorax. The beetles are commonly met with on
flowers, etc., in the daytime; and their larve are too
well-known everywhere, as WIRE-WORMS, being long and
slender, with very tough skins, and feeding on the roots
of plants.” The wire-worms gnaw, and sometimes destroy
to a serious extent, the roots of various farm crops (grain
and root, as well as fodder crops). The larve (wire-
worms) of the skip-jacks, or click-beetles, are long, slender,
and either slightly flattened or cylindrical, usually covered

Fig. 36.—Crick Berries anp WiREworRMs.
A. Elater sputator and larva,
B. Elater obscurus and larva.

C. Elater sanguineus.
(All nat. size.)

with a hard, shining, ochre-coloured skin, and furnished
with a horny head and three pairs of short legs. They
live either three or five years, according to the supply of
food. A scarcity of food means a prolonged existence in
the larval stage. In the winter the larve go deeper in
the soil, to avoid the severity of frosts. At the expiration
of the larval period, the wire-worms again go deeper in
the soil, surround themselves in earth-cells, and there
change to pupe. The pupe either hibernate until the
following spring, or appear as perfect insects in from four-
teen .to twenty-one days during the month of August
“The eggs from which these grubs are hatched are laid

90 DISEASES OF CROPS.

either in the earth close to the root of a plant, or between
the sheathing leaves near the base of the stem.”

Prevention—(1) Good cultivation and liberal manuring!
produce strong and vigorous plants, which may yield, in
spite of the land containing wire-worms, a tolerably good
crop; for it is said that the “wire-worms injure and
weaken a great deal more than they destroy.” (2) Burn
all rubbish on which the wire-worms may possibly feed.
(3) The common mole and the various insectivorous birds
(especially the “ wheat-ear”’) are the natural enemies of
the wire-worm. Mr. W. Swaysland, in his Familiar Wild
Birds, cites “as an instance of the service rendered to the
farmer by the ‘wheat-ear’ (Saxicola enanthe) and similar
birds,” that he ‘remembers a field about eight acres in
extent which one season was so infested with wire-worms
that cultivation was almost useless. The field was
ploughed and harrowed about the end of April, or the
beginning of May, and at this time large numbers of
‘ wheat-ears’ congregated there daily; in fact, they seemed
to have forsaken the surrounding localities for this par-
ticular spot. Their services in the extirpation of the
above-mentioned wire-worms may be best imagined from
the fact that after the advent of the birds the field became
productive, and a first-rate crop was the result of their
labours and assiduity.”

Cure.—(1) The soil from broken-up pastures, etc., should
be dressed with fifteen tons of gas-lime per acre. The
sulphite and sulphide of lime present in gas-lime destroy
the wire-worms, as well as other insects and weeds.
When the land is ready once more for cultivation (i.e., in

* For the most suitable manures, see Manures and their Uses, p. 42
(Bell’s Agricultural Series).

GRAMINEOUS CROPS. 91

about three or four months), the sulphite and sulphide will
have been converted into sulphate of lime (a true plant-
food) by the action of the air. (2) Twenty or thirty
bushels of salt per acre have been recommended for eradi-
cating wire-worms. (3) Miss Ormerod recommends the
use of rape-dust or rape-cake “ applied in the proportion
of five hundredweights to the acre.” The “worm” is be-
lieved to be very fond of the cake, eating it greedily in
preference to farm crops. (4) Paraffin oil mixed with
water (1 to 20) has proved an effectual remedy, especially
for infested root crops. (5) Green manuring with buck-
wheat or white mustard, destroys the wire-worms as well
as the mustard beetle.

The Skippers (Hesperia linea) belong to the Hes-
perida—a family of butterflies which (as a general rule)
carry their fore-wings upright, and their hind-wings in a
horizontal position when at rest. H. linea measures about
an inch across the extended wings. The wings are of a
bright yellowish-brown colour, with the margins and veins
blackish. These butterflies are popularly known as
“ skippers ”—so called from their short, jerky flight. The
larvee or caterpillars feed upon different species of grasses,
but do not produce the same amount of mischief as the
wire-worms. :

Moss in Pastures. The various kinds of mosses!
infesting grass lands hardly come under the designation of
“« parasites,” yet at the same time they are detrimental to
the growth of grasses ; and for this reason we include them
among the enemies of grass lands. By the growth of moss
in pastures, the grass becomes poor in quality and quantity.

Prevention.—(1) As mosses require a considerable

1 For the life-history of a moss, see any good book on botany.

92 DISEASES OF CROPS.

amount of moisture for their growth and development
all meadows and pasture lands should be well drained.
“Wherever there is moisture, even if soil be almost ab-
sent, mosses will grow; and they are the first to cover a
barren coast, as they are the last to linger when the
atmosphere ceases to be capable of affording nourishment
to vegetation” (Dr. E. Smith, F.R.S.). (2) The growth of
mosses also indicates a want of good cultivation, especially
in the use of the most suitable manures for grass lands.

Cure.—(1) The author has shown (Journal Chemical
Society, 1886, p. 114) that iron sulphate destroys moss
infesting pasture lands. After having applied a top-dress-
ing of iron sulphate to the land, the grass turned black
after the first rainfall, but in a fortnight became a bright
green colour, and the moss was destroyed. The bright
green appearance never altered in the least throughout
the summer, although the summer (1885) was rather a dry
one. The above grasses and mosses gave the following
percentages of iron oxide in their ashes :—

ASHES OF GRASS AND MOSS.

Before the addition of iron | After the addition of iron

sulphate to the land. sulphate to the land.
Grass. Moss. Grass. Moss. .
Tron oxide (Fe, Os) 0-45 6°62 2°46 11:56

The analysis of the ashes of the moss plants after the
addition of iron sulphate shows the percentage of iron
oxide is 11°56. ‘The moss, being of a greedy, thirsty
nature, took up more than was good for it, and, like some
human beings who do the same, came to an untimely end.”
In a paper published in the Chemical News (vol. 50 p. 193),

GRAMINEOUS CROPS. 93

the author showed that all the plants under investigation
died when they had absorbed iron salts to the extent of
yielding 10 per cent. of iron oxide after incineration.
Hence the reason the mosses were destroyed (by the iron
sulphate), being plants naturally requiring a larger amount
of moisture than the grasses.

The above results have been confirmed by Professors
Lambin, Bernard, Quantin, Joulie, Gaillot, Néron, De-
lacharlonny, Tord, Jaubert, and others in France,! as well
as by several well-known agriculturists in this country.
Professor Lambin says: “ Les résultats observés 4 Sois-
sons confirment ceux obtenus par M. Griffiths. Ces ré-
sultats répondent en méme temps aux craintes manifestées
sur l’emploi du sulfate de fer en agriculture. Non seule-
ment sous l’action d’une dose de 250 4 300. kilogrammes
par hectare les plantes n’ont pas souffert, mais elles ont
largement prospéré, le rendement de la prairie ayant été
presque doublé.” Mr. Macqueen, home farmer to the
Earl of Powis, considers iron sulphate “an excellent
manure for mossy pastures.”

The quantity of iron sulphate to be applied for eradi-
cating moss, is from 13 to 2 cwts. per acre. The powdered
sulphate should be mixed with two to ten times its weight
of sand or dry soil, and distributed by hand, manure dis-
tributor, or better still by means of the Strawsonizer.
The sulphate may also be applied by means of a water-
cart.2. Farmers would do well to purchase the iron sul-

1 See Journal de V Agriculture, September, 1887, October, 1888 ;
Bulletin de la Société d Horticulture de Soissons, 1887; Bull. Soc, des
Agriculteurs de France, 1888; also Manures and their Uses, p. 182,
and A Treatise on Manures, p. 275.

2 Dissolve either of the above quantities of iron sulphate (green
vitriol) in 40 gallons of water.

94 DISEASES OF CROPS.

phate (of a grass-green colour) from the nearest maker, in
the crystalline form, and powder it themselves; this would
prevent adulteration. (2) Lime has also been recom-
mended for eradicating moss, but its action is not so
certain as that of iron sulphate.

The Coronated Mildew of Grasses (Puccinia
coronata, Fig. 37) is similar in its life-history to the
“mildew of corn” (wheat), which will be described later
in this chapter. Puccinia coronata produces numberless
oval-shaped spots on various grasses. The sori (Fig. 37 B

Fig. 37.—Coronatep Mitpew (Puccinia coronata).

A. Sori on grass (enlarged).
B. Sori (enlarged).

and a) are crowded together, and ultimately rupture the
epidermis of the host-plant.

Prevention and Cure.—(1) The drainage of grass lands
has a tendency to lessen the ravages of this fungoid pest.
(2) Top-dressing pastures and meadows with -cwt. of
iron sulphate, mixed with five to ten times its weight of
sand or dry earth per acre, is a means of destroying the
mildew of grasses,

The Grass-Culm-Smut (Ustilago hypodytes) belongs
to the Ustilayinew, an important group of fungi whose
mycelia usually spread throughout the tissues of the host-

GRAMINEOUS CROPS. 95

plant. In this point the Ustilaginee differ from the
localized mycelium of most Uredinew. The grass-culm-
smut, which is sometimes common, “ makes its appearance
at first beneath the sheaths of the leaves surrounding the
stems of grasses, and ultimately appears above and around
them as a purplish-black dust.” The minute spores of this
fungus are of a brownish-black colour.

Cure. — See the method for destroying Puccinia
coronata,

The Smut Fungus (Ustilago carbo), which will be
fully described under “ The Parasites of Oats,” has been
found on the following grasses amongst others: Aira
cespitosa (hair grass), Avena flavescens (yellow oat grass),
Avena elatior (false oat grass), Avena pubescens (downy
oat grass), Festuca pratensis (meadow fescue), Lolium
perenne (rye grass), Lolium temulentum (darne] grass),
Cynosurus cristatus (crested dogstail), Festuca elatior
(tall fescue), Festuca ovina (sheep’s fescue), and Dactylis
glomerata (cocks-foot grass).

The Grass Blight (Erysiphe graminis) is similar
in its life-history to the pea mildew (Hrysiphe Martii)
already described.

Prevention.—(1) Good cultivation, clean farming, and
a liberal use of artificial manures are means of preventing
the attacks of this fungus. Farmyard manure containing
mildewed straws and grasses should not be used for grass
lands. (2) Whenever possible burn all mildewed straws
and grasses, for these retain the perithecia of this destruc-
tive fungus. (3) A thorough drainage of meadows and
pastures lessens the risk of infection, not only of this
fungoid growth, but of others as well.

Cure.—A top-dressing of iron sulphate (3-cwt. per acre)
is an effectual remedy.

96 DISEASES OF CROPS.

The Fusisporium of Rye-grass (Fusisporiwm lolii)
has a similar life-history to Fusisporium hordet, already
described. The mycelium of the first-named fungus is of
an orange colour, while that of the latter is a deep rose
colour.

The Ergot (Claviceps purpurea) of rye, wheat,
barley, and various mature grasses will be described under
the heading of “The Parasites of Rye.” The hay from
ergoted grasses is a dangerous food for farm animals.
“ Not a few cases have occurred, especially in Ireland and
the States of America, ‘where hay was found to contain
an eighth of its weight of ergot.’ The fodder caused
abortion and ergotism in cows. As a general rule, ‘ ergot
does not cause abortion, except the foetus has reached a
considerable size in the uterus.’” Prof. Sheldon (The
Farm and the Dairy, p. 138) says: “‘ Much more com-
monly than most men think, however, it (abortion) comes
from the eating of ergoted grasses, for which some cows
seem to have a morbid appetite.”

There is a varicty of ergot called Claviceps purpurea
Wilsoni, which was discovered by Mr. A. 8. Wilson on
Glyceria fluitans (sweet grass) growing in damp places.
Messrs. Plowright & Wilson (Gardeners’ Chronicle, Feb.
9th, 1884) considered it to be a variety of the ordinary
ergot. Dr. M. C. Cooke, on the other hand, looks upon it
as a separate species of Claviceps, and thereby gives it
a higher status than a mere variety.

Prevention.—Farmers should take the precaution to cut
grass when in the bloom, rather than in the seeding state ;
it will then be impossible for ergot to appear.

Cure.—Iron sulphate destroys C. purpurea (see later
in this chapter).

The Isaria of Grass (Isaria fuciformis, Fig. 38)

GRAMINEOUS CROPS. 97

was first described by the late Rev. M. J. Berkeley,
F.R.S., in the Journal Linnean Society (vol. xiii. p. 175).
This fungus occurs chiefly in the South and South-west
of England, and appears only to attack certain grasses
growing on calcareous and siliceous soils. The reason for

Fig. 38,—Isania FUCIFORMIS OF GRASSES

A. A grass infested with the fungus (a),
B. End ofa fungus tuft (a) with conidia (spores).
C. Conidia, x 670 diam. (Zeiss’ E., 4oc.)

the growth of I. fuciformis on certain grasses growing

on the previously mentioned soils, may be due to the fact

that both calcareous and siliceous soils contain (as a rule)

smaller percentages of iron oxide than argillaceous soils.
H

98 DISEASES OF CROPS.

From the author’s researches, compounds of iron appear
to be detrimental to the growth of most parasitic fungi;
and the absence of soluble, or readily assimilable iron
compounds in a soil, may produce sickly plants liable to
fall an easy prey to the attacks of parasitic fungi. Fig.
38 A illustrates a panicle of grass infested with Isaria
fuciformis, whose mycelium grows on all parts of the
host-plant, especially the leaves and stems, which it often
binds together. The fungus is chromogenic (i.e., produces
colour)—the colour of the mycelium being from pink to
red—and consists of a compact mass of cells which fre-
quently sends out aérial tufts (Fig. 38a). The cells at
the extreme ends of these tufts divide and give rise to
numberless conidia (Fig. 39 B). These conidia, or spores,
germinate on grasses, and again reproduce the mycelium
of I. fuciformis. The fungus tufts are easily detached,
and if they fall upon a suitable medium for development
they reproduce the mycelium of the fungus. Very little
(beyond what has already been stated) is known of this
fungus or its habits. “It is quite possible that I. .fuct-
formis may be an early condition of a Torrubia belonging
to an insect or plant host.” Certain species of Torrubia
infest truffles, mosses, and insects. It has been stated
that grass infested with I. fuctformis produces a diseased
state of the lungs when farm animals are fed upon it; but
this statement requires confirmation.

Prevention.—(1) The drainage of all grass lands, es-
pecially those in the South and South-west of England,
has a tendency to lessen the attacks of this fungoid pest.
(2) As I. fuciformis only makes its appearance from Sep-
tember to the following January, it would be well for
farmers to remove the grass before the appearance of the
fungus.

GRAMINEOUS CROPS. 99

(4) THe Parasires or Oats (Avena sativa).

Aphis granaria, Cephus pygmeus, Tylenchus devasta-
trix, Tylenchus Havensteinii, and various wireworms
(which have already been described) attack Avena sativa.

The Frit Fly (Oscinis vastator, Oscinis frit) is

a small dipterous insect which attacks barley and wheat,
as well as oats. This fly caused serious. damage to the
oat crops of 1887. It is about 2} lines,! or a little more
than 2 of an inch, in length, with a blackish head, thorax,
and abdomen. The feet are yellowish, while the haltéres
(or the rudiments of the posterior wings of other insects)
are of a light buff colour. The female fly lays white eggs
on the leaves of the above-mentioned crops, from which
white grubs make their appearance in a short time. The
grubs (like those of Chlorops teniopus, Cephus pygmceus)
infest the stems of and live upon the soft tissues and juices
of corn plants. The grubs of this fly are about + inch
long, and are devoid of legs. They turn to pups of a brown
colour; aud, according to Dr. Nérdlinger (Die Kleinen
Feinde der Landwirthschaft), the pupe may hibernate
on grasses or in the earth. There are several broods
during the summer. In France, Germany, and especially
in Sweden, the grubs live on “ the growing grain,” as well
as infest the stems of the host-plants. The ravages of this
farm pest are greater during a dry than a wet season.
' Prevention.—After oats or any other corn crop has been
infested with this insect, ploughing up the land has been
recommended as a preventive against a subsequent attack
during the next season.

Cure.—It has been suggested, that before sowing oats
infested with the brown pupe of this fly the seed should

1 1 line=¥y, inch.

100 DISEASES OF CROPS.

be steeped in a solution of copper sulphate or common
salt.

The Smut Fungus (Ustilago carbo, Fig. 39) pro-
duces the well-known black and withered ears of corn,
It attacks barley, wheat, and certain grasses, as well as
oats. The disease is said to originate in the roots of the
host-plants, and passes up the stems into the leaves and

Fig. 89.—Tuz Smut or Corn (Ustilago carbo).

A. Oats infested with Ustilago carbo (a),
B. ‘Sori’ on a portion of a glume of oats.
C. Spores x 320 (Zeiss’ D., 30c.).

E&D. Aspore germinating.

panicles. The spikelets (Fig. 39 A) become covered with
masses (sori) of black or primary spores, which work their
way from within outwards, and ultimately rupture the
epidermis of infested plants. The small globular spores
are of a dark-brown colour, almost black (Fig. 39 C).
These spores give rise to “buds” (Fig. 39 EK), which ulti-
mately form secondary spores, or conidia. The secondary
spores are produced by what is known as the process of

GRAMINEOUS CROPS. 101

gemmation, which may go on indefinitely—so long as the
medium in which the spores live is suitable for this
method of reproduction. In this respect (i.e., reproduction
by gemmation) Ustilago carbo resembles the cells of
Torula cerevisie (the yeast organism), and better still those
of Torula apiculatus. The secondary spores continue pro-
ducing the same spores, or give rise to germ-tubes (hyphee,
Fig. 39 D) which germinate on, and produce a mycelium
within, the tissues of the host-plant. It is possible that
conjugation! takes place between the spores of the smut
fungus, for this method of reproduction is not uncommon
in the genus Ustilago. The spores of the smut fungus are
to be found in the soil, air, and on the seeds of oats, barley,
and wheat before sowing.

Prevention.(1) Destroy all affected ears at the earliest
stage when the disease is visible, and before the spores
have ripened. (2) “Burn all smutted grasses.”

Cure.—(1) The author has shown that steeping the
grain before sowing in a 2 per cent. solution of iron
sulphate for three or four hours entirely destroys any
fungal spores which may be upon the seeds; and this
method does not injure the germinating power of the
grain, (2) A solution of copper sulphate? has often been
recommended for the same purpose, but there is little
doubt that this reagent frequently destroys the germinat-
ing power of seeds (Biedermann’s Centraiblatt ftir Agrit-
cultur-Chemie, 1886, p. 766). Mr. J. L. Jensen (Journ.
Roy. Agric. Society, 1888, p. 397) says that “dressing
cereals with copper sulphate in the usual manner against
smut and bunt causes, as a rule, a waste of the seed-corn.

1 The production of a spore by the union of two “like” cells.
2 1 1b. dissolved in 5 quarts of water for 4 bushels of grain.

102 DISEASES OF CROPS.

It is injurious to the plants.” (3) Another remedy is to
make a strong solution of sodium sulphate (Glauber’s salts)
‘in which the seed-corn is to be washed, and afterwards,
whilst still moist, dusted over with quick-lime.” The
reader who is acquainted with chemistry will readily
understand the reaction which takes place by referring
to the following equation :—

Na,SO, a i CaO = Na,O + CaSO,.

“The caustic soda (Na,0) is fatal to the germination of
the spores of bunt” as well as those of smut. (4) Other
‘ steeps” for destroying the germs of disease are or have
been used by agriculturists. Amongst these are the
following: Arsenious acid and soda, slaked lime, salt, a
weak solution of potassium permanganate, and a weak
solution of carbolic acid. But all these substances are
more or less detrimental to the germinating properties of
grains. Damaged grains produce sickly plants, and sickly
plants run the risk of becoming diseased. (5) Mr. J. L.
Jensen recommends “treating the seed-corn with water
heated to a temperature of 127° F. for five minutes, which
destroys the fungal spores without injuring the seed-corn
or the resulting crop.” But the most effectual and re-
liable method, in our opinion, is the use of a solution of
iron sulphate. The author’s investigations on this subject
have been confirmed both in France! and Germany as
well as in England.

(5) THe ParasiTes oF Rick (Oryza sativa).

The Rice Weevil (Calandra oryze) belongs to
the same genus as the common corn weevil (Calandra
granaria), the palm weevil (Calandra palmarum), and

' See Prof. Quantin’s paper, Journ. de VAgric., 1888.

GRAMINEOUS CROPS. 103

many other destructive species which are plentiful all
over the world. The rice weevil is of small size, not
more than an eighth of an inch in length, and is well
known in the Colonies and India by the characteristic
four red spots on the black elytra. This insect is de-
structive to Indian corn and wheat as well as rice.

On the authority of Mr. C. Whitehead, F.LS., “C.
oryze does enormous harm to wheat in Indian granaries,
and to wheat while it is being transported in vessels to
this country. The admixture of dirt, seeds, and rubbish
causes the wheat to heat, which is detrimental to its
quality, and at the same time causes weevils to propagate
unusually and to materially damage it. Sometimes the
cargoes of wheat that have been heated are nearly alive
with weevils, causing great waste and heavy loss to im-
porters. This loss continues when the bulk is taken to
granaries or warehouses where the heat is still evolved,
and the weevils revel in it. The amount of loss occasioned
by this weevil is estimated at an average of 2} per cent.
Taking the value of wheat exported at £6,000,000, the
amount of loss due to this insect in exported wheat alone
equals £150,000 ” (Wature, vol. 40, p. 841).

There are two principal fungi that cause disease in
the rice crops of India and the Colonies. The first is the
smut fungus (U. carbo) already described ; and the second,
Claviceps purpurea (the ergot of cereals and grasses),
which will be described later in this chapter.

(6) THe Parasites or Rye (Secale cereale).

The Grain Aphis (A. granaria) has already been
described as an enemy of barley, oats, and grasses.

The Eelworms (Tylenchus devastatrix and T.
Havensteinii), described in chapter ii., cause considerable

104 DISEASES OF CROPS.

damage to the rye crops of Germany and Holland. The
disease known by the names of “ knopf,” “rib,” and
“stock,” is due to injury caused to rye plants by the
above-named nematoids.

The Wire-worms, already described, seriously in-
jure rye plants.

Fig. 40.—Tue Ereor or Ryn, etc. (Claviceps purpurea).
A. An ear of rye with ergots (a).
B. A section through an ergot (in its early condition); at b isa mycelium
bearing conidia (x 270).
C. A germinating ergot (a sclerotium), (nat. size).

The Ergot of Rye (Claviceps purpurea, Figs. 40
and 41) is nothing more than a sclerotium or compact
hard mycelium of the above-named fungus. The ergots

GRAMINEOUS CROPS. 105

of rye are so familiar to farmers that little need be
said of their external characters. They are elongated
blackish growths found on spikes of rye (Fig. 40 A) and
other cereals as well as on certain mature grasses. A
microscopic section through an ergot (Fig. 40 B) shows
a compacted mass of irregularly shaped and very thick-
walled cells. In what is known as the “ early condition,”
an ergot gives rise to a loosely matted mycelium bearing

<

Fig. 41.—Claviceps purpurea.

A. Asection through the spherical head of the fungus, showing a number of
conceptacles (a), x about 11 diam.

B. Asection of a conceptacle, showing a number of asci (b), x 95 diam.
(Zeiss’ B, and 2oc.). a

C. Asporidium. x 270 diam. (Zeiss’ E, and loc.).

conidia (Fig. 40 b). This early condition was at one time
considered to be a parasite of ergot; but it has been
demonstrated that the so-called Oidium abortifaciens is
nothing more than an early stage in the life-history of
Claviceps purpurea. The oidium-conidia germinate, and
reproduce either the oidium-mycelia or the early stage of
ergot. When the ergots attain their full size the oidium-
mycelia atrophy, and ultimately fall away. Ergots retain
their vitality for about two years, and when the surround-
ings are favourable they germinate (Fig. 40 (). Each

106 DISEASES OF CROPS.

mature ergot gives rise to a perfect fungus bearing small
globular heads of a pale violet colour. When a longitu-
dinal section through one of the globular heads is
examined under a low power of the microscope, a number
of conceptacles are observed round the periphery of the
head (Fig. 41 A). These conceptacles, or flask-shaped
cavities, open outwards, and each contains a large number
of elongated asci (“‘sacks’’) containing sporidia (Fig. 41
Band C). In England, these sporidia or spores are pro-
duced in June and July; but the time for spore-formation
must necessarily depend upon the nature of the host-plant
and the environment.! When the asci are ripe, the con-
tained sporidia are liberated. The latter fall upon the
young flowers of rye, where they germinate, and ulti-
mately give rise to ergots.? The gradual formation of the
compact mycelium (ergot) of this fungus is at the expense
of the host-plant, which is greatly injured during the
latter stages of its growth. Ergots grow upon wheat,
barley, rice, and many grasses.

Ergoted fodder produces abortion and ergotism in farm
animals.

Prevention.—(1) A good system of drainage lessens the
liability of infection. (2) Farmers should take the pre-
caution to cut grass when in bloom, rather than in the
seeding state; it will then be impossible for ergot to
appear. (3) In the case of ergoted grasses, a scythe
should be used for cutting off their “tops.” The latter
should be raked together and burnt.

1 Tt is earlier in hot climates.

2M. Tanret (Comptes Rendus [1889}, vol. 108) has recently iso-
lated a new substance from ergots, which he terms ergosterine
(C5:H490,). Ergosterine is an alcohol (monoatomic).

GRAMINEOUS CROPS. 107

Cure.—Iron sulphate destroys Claviceps purpurea.
All lands liable to the attacks of this fungus should be
top-dressed with iron sulphate (from 4 to 1 cwt. per acre).

The Smut Fungus (Ustilago carbo) has already
been described under “The Parasites of Oats.”

(7) Toe Parasites or WHEAT (Triticum vulgare).

Aphis granaria, Cephus pygmeus, Chlorops teniopus,
Oscinis frit, and the various species of wire-worms, all
attack and greatly injure wheat crops. As these insects
have already been described, nothing further need be said
of them.

The Corn Weevil (Calandra granaria) is the pest
of corn-dealers, for it passes its “larval state within the
grain on which it feeds, devours the whole of the interior,
and then, gnawing its way through the shell, becomes
transformed in process of time into its perfect state.”
The beetle, or perfect insect, is about one-sixth of an inch
in length, and is entirely of a blackish-red colour. It is
found abundantly in granaries, and is brought over (in
large quantities) with Indian wheat. It breeds freely in
this country—the female laying an egg in each grain of
corn visited for the purpose; and the larve hatched from
the eggs bury themselves in the substance of the grains
upon which they feed in security. ‘“ When full grown
they undergo their change to the pupal state, in the con-
venient little chamber which they have thus formed, and
on attaining their perfect state, make their appearance in
the world by eating through the husk of the corn.” C.
granaria is one of the most destructive of the family of
weevils. “ Besides the actual money loss occasioned by
these weevils, it is stated that the flour made from wheat
much infested by them is injurious to health.”

108 DISEASES OF CROPS.

Prevention.—Infested seeds should not be sown.
Farmers should make a practice of examining their seeds
—and especially foreign seeds—before sowing or drilling.

Cure. — (1) “Kiln-drying, if judiciously performed,
would destroy the larve, without affecting the germinat-
ing power of the seeds. About 120° F. is held by some
authorities to be a safe and sufficient maximum of heat
to accomplish this.” But it must be borne in mind that
kiln-drying is of use only for comparatively new seed.

Fig. 42.—Corn Turirs (Thrips cercalium).

A. Corn thrip (enlarged).
B. Its nat. size.
C. Larva of thrips (enlarged).

What would be the use of kiln-drying seeds which have
already lost the greater part of the farinaceous matter
and possibly the germs damaged by the larve of this
pest? It is impossible for such seeds to produce any-
thing like satisfactory crops. (2) Washing the floors,
etc., of granaries with soft soap and paraffin oil, and lime-
washing the ceilings, destroy this pest.

The Wheat or Corn Thrips (Thrips ccrealiwm,
Thrips tritici, Fig. 42)! belong to the natural order
Physopoda. The members of this order are generally

1 For an excellent account of various species of Thrips, see Linde-
man’s Die am Getreide Lebenden Thrips arten Mittelrusslands, pp.
1-42.

GRAMINEOUS CROPS. 109

furnished with four nearly equal, flat wings, destitute of
veins; but are provided with very long and delicate
hairs, which extend all round the wings. All the species
of Thrips are remarkable for the “ power of executing
leaps of considerable extent in comparison with their
size, by the agency of their abdomen, which they bend
under them, and suddenly extend.” T. cerealium is a
small blackish species, not more than one-tenth of an
inch in length, which infests the ears of wheat in all
stages of growth. According to Vassali-Enandi (an
Italian authority), this insect also “attacks the stems of
the wheat plants, gnawing them above the knots,” It
destroys the plants by extracting their juices—thereby
causing a lowered vitality, resulting in disease. The
male insect is devoid of wings. The metamorphosis is
incomplete, the larva being as active as the perfect insect,
to which it bears a close resemblance both in structure
and habits. In colour both larve and pupe are yellow,
while the perfect insects are black.

Various species of Thrips attack grasses, clover,
potatoes, hops, and other plants.!

Prevention.—(1) As these insects prefer moist situa-
tions to dry ones, it is advisable to thoroughly drain all
wheat-growing lands. (2) Miss Ormerod states “that
Thrips do most mischief to late-sown wheat, the early-
sown crop being too hard at the time the Thrips appear
(i.e., in June) for them to injure it.” Good cultivation,
and the judicious use of manures, are important (although
indirect) means of preventing the attacks of this farm
pest. Cereal crops generally are greatly benefited by
manuring the land with soluble and insoluble phosphates,

1 Dr. Riley’s Insect Life, vol. i. p. 141.

110 DISEASES OF CROPS.

potash, and nitrogen (either in the form of nitrate of soda
or ammonium sulphate). Farmers should bear in mind
an old saying attributed to Arbuthnot, that “he who
sows his grain upon sand will have many a hungry belly
before his harvest.” When soils are properly manured,
healthy and vigorous crops are the result. Such crops
are better capable of battling with the various destructive
insects than those grown upon impoverished or poor soils,

The Cockchafer (M. vulgaris), one of the largest
of the British Coleoptera,! has already been described as
a pest of grasses. The larve also feed upon the roots of
wheat and other cereal crops, often causing a considerable
amount of damage.

The Corn Moth (Tinea granella) is found abun-
dantly in granaries in June and July, “ when it lays its
eggs upon each grain. The young larve, when hatched,
eat their way into the interior of the grain and feed in
concealment upon its substance; but when this portion of
food is consumed, each larva unites three or four grains
together with a web, so as to form a little habitation, in
the interior of which it feeds.” TJ. granella belongs to
the same tribe as the common clothes-moth.

The Wheat Flour Moth (Ephestia kuhniella) has
only been known in England about three years. “In
1887 the caterpillars of this moth did great harm in some
large stores in London, and in 1888 the attack established
itself in a wheat-flour steam-mill in the north of England.
The great harm caused is by reason of the caterpillars
‘felting’ up the meal or flour by the quantity of web
which they spinin it. . . . This clogs the mill appa-

1 The Rev. Canon Fowler, M.A., F.L.S. (of Lincoln) informs the
author that, at least, 100,000 species of the Coleoptera are known.

“ GRAMINEOUS CROPS. 111

ratus to a very serious extent. . . . The moth is
about three-fourths of an inch in the spread of the fore
wings, which are of pale grey with darker transverse
markings; the hinder wings are remarkable for their
whitish semi-transparency, with a darker line from the
point along a part of the fore edge. The larve, when
full grown, are about five-eighths of an inch long, of a
palish flesh-colour, lighter when older, and heads of a
yellowish-brown colour.’’!

Fig. 48.—Tue Hessian Fuy (Cecidomyia destructor).
A.and B. The fly (nat. size and enlarged).
C. Pupa-cases of the fly (nat. size).
D. Pupe in joint of stem.

Prevention and Cure——Miss Ormerod writes that she
“has much reduced their (the larve) numbers by getting
the manager of the steam-mill to turn on scalding steam ;
and cleaning, white-washing, and some use of paraffin
have done good. The real cure would be to change the
material ground. If we could use rye-meal for a few
weeks, we could clean out this wheat-flour feeding cater-
pillar effectually.”

The Hessian Fly (Cecidomyia destructor, Fig. 43)

1 Miss Ormerod, in Riley’s Insect Life, vol. i. p. 315.

112 DISEASES OF CROPS.

is one of the most formidable foes of wheat and barley
crops; but it does not attack oats. This dipterous fly
has been known in the northern continent of America
for over a hundred years. The earliest recorded attacks
of the true Hessian fly in England was in the summer
of 1886; although, according to Dr. K. Lindeman (Die
Hessenfliege in Russland"), it was first observed in Russia
six years earlier than in Great Britain. As C. destructor
is often the cause of a wholesale destruction of the wheat
crops in America, it has earned the name of the “ North
American scourge”; but up to the present date the
Hessian fly has not done much damage in our islands,
where it has confined its attacks to the eastern coun-
ties. Although this fly is “‘an insect of moist climates
and mild latitudes,” Dr. C. V. Riley says: “that there
is very little danger of any such injury in England as
is suffered in America and in portions of Continental
Europe.”? Since the visitation of this fly in Great
Britain, the damage done by it has been estimated at a
loss of one to twelve bushels of grain per acre. The
female fly lays its eggs upon the stems of wheat and
barley, i.c., between the stem and the leaf-sheath. The
eggs (pointed at both ends) are about the one-fifteenth of
an inch in length, and of a red colour. The female® de-
posits singly about eight eggs, and then takes flight,
These eggs are glued together by means of a sticky
secretion. The white larve, which are devoid of legs,
are hatched from the eggs in fourteen days. After estab-
lishing themselves, as a rule, just above the second joints,

} Bulletin de la Société Impériale des Naturalistes de Moscow, 1887.
2 Insect Life, vol. i. p. 133.
3 Hach female lays about 230 eggs in a seagon.

GRAMINEOUS CROPS. 113

the larvee feed upon the juices of the host-plants, and
weaken them to such an extent, that when the ears begin
to be formed, the straw is no longer strong enough to bear
their weight, but falls to the ground as though beaten
down by strong wind and rain. It must be borne in mind
that ‘‘ the Hessian fly maggot does not feed in the ear, nor
does it feed along the outside of the upper part of the
stem.” The ribbon-footed corn fly (Chlorops teniopus)
feeds in the ears of corn, etc., and has been mistaken, by
some, for the Hessian fly.

According to Dr. Lindeman (paper loc. cié.), the Hessian
fly lives about twenty-eight days in the larval stage, it
then changes to a brown pupa (Fig. 43 C and D) some-
what resembling a small “ flax-seed.” Hence the reason
that the puparia are sometimes spoken of as “ flax-
seeds.” The period that the insect remains in the pupal
stage depends upon circumstances. On the authority of
Miss Ormerod, “it may occur, under natural and favour-
able circumstances, so soon that the whole time occupied
in the life of the fly from egg to development is only about
forty-eight days”; or, it may hibernate in the pupal
stage until May or even later in the following year. The
perfect insect (Fig. 43 A) is about five-sixteenths of an
inch across the expanded wings and with a body-length
of two lines ({th in.). The head of the male is black,
with long brown antennz and small pink proboscis. The
thorax is black with two lines of white hairs running
along the dorsal side, and also a few similar hairs on each
side of the thorax. The abdomen of the male is black,
except at the’ posterior end, where it is of a pinkish
colour. The posterior end of the abdomen “is provided
with a pair of claspers of a brown colour, between which

are seated the generative organs.” The wings, which are
I

114 DISEASES OF CROPS.

of a pink colour at the base, are covered with black hairs,
The haltéres are of a pale red colour. The female insect is
about one-third longer than the male, and has a yellowish-
brown abdomen containing a number of spots on each of
the eight segments. The legs of both sexes are of a pink
colour ; but they are of a darker shade in the female.

There are generally two broods of this insect in each
season, Qn the authority of Dr. C. V. Riley, it has been
stated that the Hessian fly “‘ is very injurious only under
conditions where two annual generations are pretty uni-
formly produced ; and he is satisfied that in England, as
a rule, only one generation will be produced.” Mr. J. E.
Mason, of Alford (who reported the discovery of the pest
in Lincolnshire during the season of 1889), wrote the
author as follows: “ As regards the amount of damage,
I have come to the conclusion that in our country it is
not at all likely to be serious among the wheat, but that
it may be very extensive in the barley crop.”

Fortunately for British agriculture there are certain
parasites of Cecidomyia destructor which accompany it
to this country. Amongst these are the following:
Euryscapus saltator, Platygaster minutus, Hupelmus
karschii, Tetrastichus Rileyi, Semiotellus nigripes, and
Merisus intermedius. They are all small four-winged
flies, belonging to the Hymenoptera, which ‘lay their
eges in the larve and pupe of C. destructor. The
parasites mentioned infest the Hessian fly in Russia, and
therefore must have been introduced into England (along
with their host) upon imported Russian wheat. They are
quite distinct species from those found in America (Linde-
man’s Div Pteromalinen der Hessenflicye, p. 15).

1¥or further information, see Riley’s Parasites of the Hessian
Fly, and Insect Life, vol. i. p. 132; Ormerod’s The Hessian Fly in

GRAMINEOUS CROPS. 115
Prevention.—(1) In those counties (Hertfordshire, Bed-
fordshire, Lincolnshire, Cambridgeshire, etc.) where the
Hessian fly has been pretty active during the past three
years, it would be well for farmers, wherever possible,
to avoid sowing either barley or wheat late in the season.
Early-sown crops appear to resist the attacks better than
those late sown. (2) The stout stiff-strawed varieties of
wheat and barley resist the attacks of this pest better
than other varieties. Among the “ resisters” may be men-
tioned the following: “ chaff red,” “ square head,” “ stand-
up white,” “golden drop,” “Rivett’s red;” and among
the barleys should be mentioned: “‘ Kinver,” “‘battledore,”’
“bere,” and “awnless.” The finer varieties of barley
(e.g.. “peerless white,” “golden melon,” etc.) have all
been infested in this country. (8) It is recorded that
wheat crops (which follow clover in a rotation) grown
upon a poor sandy loam, previously manured with fifteen
tons of dung per acre, followed by a top-dressing of two
cwts. of nitrate of soda and one and a half cwt. of salt per
acre in the spring, resisted the attacks of the Hessian fly.
On the other hand, a similar crop treated with the same
amount of dung minus the top-dressing of artificial ma-
nures “suffered severely from the attack of Hessian and
sawflies.” (4) Corn and straw imported into this country
should be carefully examined for puparia (‘‘flax-seeds”),
and if found they should be burnt. (5) “In corn fields
where ‘ seeds’ are not sown, the stubble should be cut as
high as possible, in order that the pup may be left upon
it. Then at once after harvest the land should either be

Great Britain; Nowicki’s paper in Verhandlungen der K. K. zoolo-
gisch-botanischen Gesellschaft in Wien, vol. xxiv. p. 855; Lindeman’s
paper in Entom. Nachr. xiv. p. 242; Enock in The Entomologist, vol.

xxi. p. 202.

116 DISEASES OF CROPS.

deeply ploughed, so that the stubble may be buried; or it
may be cultivated, or scarified and the stubble harrowed
together and carefully burnt” (Whitehead). (6) Farmers
should “destroy ‘ flax-seeds’ found (after threshing in-
fested straw). in siftings or light grain.” (7) In the
United States of America stubbles are burnt as they
stand. In some cases this method might be advantage-
ously applied in England.

Cure.—(1) Dressings of gas-lime, in either the autumn
or spring, have been recommended for destroying the

a

: ae =

Fig. 44.—Tur WueEat Mince or Fy (Cecidomyia tritici).

A. Larve feeding on wheat.
Band C. Larve (nat. size and enlarged).
DandE. The fly (nat. size and enlarged).

larve, ete., of this pest. (2) Applications of lime, or a
mixture of soot and lime, are also recommended for the
same purpose,

The Wheat Midge (Cecidomyia tritici, Fig. 44) be-
longs to the same genus, and is therefore a near relative
of the Hessian fly. It is a small, pale, orange-coloured
fly, with clear, almost veinless wings. The female fly
visits the florets of the wheat just as they are opening,
and deposits its eggs amongst the reproductive organs of
the florets, by means of a long, extensible ovipositor. The
eggs (which are oblong and transparent) are hatched in

GRAMINEOUS CROPS. 117

about ten days. The small red larve (called “ red gum ”
by farmers) from these eggs feed upon the “germs”
of the florets, which often renders them abortive. It
is said “that as much as five per cent. of the crop is
frequently destroyed by this injurious insect.” When
full-grown, the larve go down to the ground, and are
there transformed into reddish-coloured pupe. The
pupe either hibernate or turn to perfect insects during
the month of June (i.c., according to whether the brood
has been a late or an early one).

Prevention.—(1) Deep ploughing. (2) Destroy those
grasses (especially Avena fatua [wild oat grass]) upon
which the larve of the wheat fly feed. (3) Asa number
of larve may be in the ears of corn, it is advisable that
the chaff, etc. (after threshing), should be carefully ex-
amined. If any maggots are found, they should be
destroyed. (4) The firing of infested stubbles has been
recommended.

Cure.—See those mentioned for destroying the Hessian
fly.

The Wheat Bulb Fly (Anthomyia coarctata, Musca
coarctata) is a grey-coloured fly, about one-third of an
inch in length, and measures half an inch across the
extended wings. According to Megnin (L’Insectologie
Agricole), the tarsi of the females are of a red colour,
whilst those of the male are black. The white larve, or
maggots, are about the same length as the body of the
perfect insect. They are devoid of legs, but are pro-
vided with “teeth” and “hooks” at their posterior ends.
The larve of this fly turn to brown-coloured pupe in the
earth. During the season “ there are two generations.
One is commenced by eggs laid upon autumn-sown wheat
plants. Flies of the second generation appear again in

118 DISEASES OF CROPS.

the early part of the summer, and place their eggs, it is
presumed, upon backward and spring-sown corn, or upon
grasses.” The larve of this fly live within the bulb of
the wheat stems.

Prevention.—In districts liable to the attacks of this
pest, wheat should not be sown too early.

Cure.— Dressing the land with gas-lime, or quicklime,
and soot destroys the pupe.

Ear-Cockles in Wheat (Tylenchus tritici). In the
disease known as “ ear-cockle,” ‘“ pepper-corns,” and
“purples,” the grains of corn in the spikelets become
replaced by galls of blackish hue. The galls are pro-
duced by a small nematoid, the Tylenchus tritici of Dr.
H.C. Bastian, F.R.S. (Monograph on the Anguillulide,
and Memoirs on the Nematoids: Parasitic and Free).
This nematoid belongs to the same genus as those already
described under the name of “eelworms.” The galls are
always to be found within the pales and flowering glumes
of infested wheat ; and, according to Dr. Devaine (Re-
cherches sur VAnguillule du Blé niellé), are “formed
from any of the growths belonging to the central part of
the flower.” Grains affected in the growing crop turn
first dark-green, then nearly black. They become mis-
shapen, acquire the form and size of peppercorns, and
very nearly resemble cockle-seed and wild vetches. The
vetch has a smooth skin, whereas the ear-cockle has a
rough surface. If seen in the standing corn, they may
at once be recognised, as the glumes (chaff) of the diseased
grains are spread open to an abnormal degree, while the
awns are considerably twisted. If one of the mature
diseased grains is cut in two, it will be found to contain
a mass of white, cottony-looking substance, which so
resembles the meal found in wheat as to be passed by the

GRAMINEOUS CROPS. 119

ordinary farmer as such. If a small portion of this
cottony-looking substance is placed in a drop of water,
and examined under the microscope, it will be seen that
there are a number of minute worms, which twist and
wriggle about in the most excited manner. No sooner
does the moisture dry up than they at once become in-
active, and remain dormant until again supplied with
water. These small nematoids are capable of being dried
and revived many times before they are killed. “They
have the extraordinary faculty of retaining vitality for
many years, even though they are perfectly desiccated.
Four or five years is by no means an uncommon duration
of life in such conditions.” Mr. W. Carruthers, F.R.S.,
states “that vitality was restored in some eelworms (of a
different species) after they had been in the botanical
department of the British Museum for more than thirty
years.”1 A fully grown Tylenchus tritict is about the
one-sixth of an inch in length. The sexes are separate,
and pairing takes place within the host-plants, where
large numbers of microscopic eggs are deposited. These
eggs are hatched in about fourteen days, and quickly
grow into the cotton-like masses previously described.
T. tritici infests also oats, rye, maize, and certain grasses.?
These nematoids are propagated to an unlimited extent
when a few ear-cockle grains are sown among seed-wheat.
It has already been stated that these ‘‘worms” are capable
of being desiccated without losing their vitality; and
when the surroundings are favourable, they travel through

! See also Bastian’s paper in the Transactions Linnean Society,
vol. xxv. "

2 Festuca elatior (tall fescue), Agrostis stolonifera (fiorin grass),
Agrostis vulgaris (bent grass), ete.

120 DISEASES OF CROPS.

the soil to the adjacent wheat plants, ascend the stalk
until they reach the flowers, where the attack com-
mences.

Prevention.—(1) The land should be well drained, for
these pests love moisture. (2) The farmer should use
every precaution. If once his farm is infested with this
pest, he will find great difficulty in exterminating it.
Fortunately the galls containing the ‘ worms” are easily
detected (being black and only half the size of wheat-
grains) among seed-wheat ; but they are not all separated
from the chaff by winnowing, for many are blown over
with the chaff, and thus propagate the pests when put on
the land with the manure. When the cottony mass from
a quantity of wheat affected with ear-cockle is extracted
in the grinding process, it does not kill these minute
organisms, so that they.are cast aside with the bran, and
thus too often find their way back to the fields. Grain
that is only roughly ground for farm animals is still more
liable to be a means of spreading the pest. As stated
before, numbers of ear-cockles are blown over during the
process of winnowing; and under such circumstances,
the chaff contains a whole host of what will prove to be,
if caution is not practised, parents of a future generation.
The only way to destroy them is to burn the chaff. (3)
Top-dressing the land with the following mixed manure—
1 cwt. each of kainit, nitrate of soda, superphosphate of
lime, and 13 cwt. of salt per acre—proved most beneficial
(for wheat) on certain farms previously infested with this
pest.

The Wheat Milliped (Julus londinensis), like J.
terrestris (already described), is one of the so-called false
wire-worms. The wheat milliped has shorter antenne
than Julus terrestris, and, unlike the latter species, the

GRAMINEOUS CROPS. 121

pre-anal segment is rounded. J. londinensis feeds upon
the roots and rootlets of wheat plants.

Prevention and Cure.—(1) Green manuring with buck-
wheat destroys this pest. (2) Top-dressings of quicklime
or gas-lime also kill the wheat milliped.

Trombidium trigonum is a small arachnoid or
“spider,” and, on the authority of Curtis, injures the
spikes of corn, especially in France. On the other hand,
Mr. Walker and others in England assert that it feeds
upon the aphides that infest ears of corn, but does not
injure the corn.

The Wheat Blight, or White Rust (Erysiphe
graminis), ‘forms a white superficial mildew on the
living stems and leaves of cereals and other grasses in the
summer and autumn.” It has already been described in
chapters ii. and iv.

The Smut Fungus (Ustilago carbo) has been de-
scribed in the present chapter; “ but how smut infects
wheat has long been a mystery. The spores ripen in the
young flowers, and have disappeared long before the grain
is mature. Attempts at infection of the grain or seedling
are almost always unsuccessful. . . . The experi-
ments of Jensen render it most probable that the plant is
infected by the spores while flowering, and that either the
ovum itself is entered by the mycelium, or that the spores
remain dormant in the grain until its germination, and
that then the parasite ‘grows with the growth and
strengthens with the strength’ of the young plant” (Dr.

Scott).

’ The Straw Mildew, or Blight, is the cause of a
well-known diseased condition of the stems of numerous
members of the Graminee (barley, rye, wheat, and
various grasses). The complete life-history of the straw

122 DISEASES OF CROPS.

blight is unknown, but ve that portion which is called
the vegetative or « larval” condition of a fungus. This
fungus attacks the stems near the roots; it seldom ox-
tends further than the third joint, and is frequently found
below the second. The “straw blight” (as far as is
known) simply consists of a ramifying mycelium, whose
hyphee pass through the cell-walls of the host-plant, and
thereby greatly injure the infested plant. The fungus
often stops growth, and sometimes proves fatal to plant-
life. Infested crops are considerably reduced in quantity
as well as quality. Upon this point the following facts
may be recorded :—

During the seasons of 1887 and 1888, the author grew
meadow hay upon a sandy loam which had previously
grown barley. Before laying down for grass, the soil
was well manured with farmyard manure, and during the
early spring (1887) the grass was top-dressed with a
mixture containing 1 cwt. each of guano and sodium
nitrate, and 2 cwts. of superphosphate of lime per acre.
In May of the same year, the grass was top-dressed with
3 cwt. of iron sulphate per acre. At the harvest (June,
1887), the crop yielded 2 tons 8 cwts. of hay per acre. In
the autumn of 1887 the same land was treated with 10
tons of farmyard manure per acre, and in the early spring
of 1888 received a top-dressing of the previously men-
tioned “ mixed manure,” minus the iron sulphate. As the
spring advanced, it was observed that nearly the whole of
the grass was, more or less, infested with the so-called
“straw blight.” As it was interesting to compare the
yield, etc., of hay from the infested field with the previous
year’s crop, only a very narrow strip of grass was top-
dressed with iron sulphate (} cwt. per acre) to observe
its effect upon the mildew. At the harvest (1888) the

GRAMINEOUS CROPS. 123

infested field yielded 1 ton 9 cwts. of hay, or a reduction
of 19 cwts. per acre on the previous year’s crop. Fair
samples of hay (dried at 100° C.) from each crop gave on
analysis the following results :—

1887 Crop 1888 Crop ‘
(not infested). | (infested), Difference.

Albuminoids (flesh formers) . 11-24 8:31 2°93

Soluble carbo-

hydrates .| Heat and 45-61 42°36 3-25

Woody fibre . 33-02 38°98 5°96

Die oes | producers 3-11 3-04 0-07

ABH gos igh ee oe TOL 7:31 0:30
99°99 100-00 a

The above table shows that the most valuable consti-
tuents (albuminoids and soluble carbohydrates) are con-
siderably reduced in the hay from the infested crop;
while the woody fibre! is increased by nearly 6 per cent.
It must be remarked that the spring and early summer of
1887 were dry, while those of 1888 were wet, and there-
fore promoted the growth of the straw blight. After the
previously mentioned strip of grass land had been treated
with iron sulphate, the grass became healthy and de-
veloped a bright-green colour. Microscopical sections of
this grass were examined, but not the slightest trace of
the straw blight was perceptible.

The straw blight, as already stated, attacks cereals as
well as grasses. It is sometimes prevalent (especially in
wet seasons) in the spring and summer, and may be re-
cognised by the appearance of brown spots near the base
of infested stems.

1 Woody fibre is digested with difficulty by farm animals.

124 DISEASES OF CROPS.

Prevention.—The drainage of the land lessens the
attacks of this pest.

Cure.—Top-dressing the land with iron sulphate de-
stroys this fungoid growth.

The Bunt of Wheat (Tilletia tritici, Tillctia caries)
is a fungoid disease which confines itself to the grains
within the ears. Infested grains are of a darker green
colour, besides being shorter and wider than healthy
ones. The interior of an infested grain consists of an
exceedingly large number of brownish-black spores pos-
sessing a putrescent fishy odour. These dark-coloured
spores are globular and slightly spinulose. They either
give rise to a short mycelium (pro-mycelium) which bears
eight or ten elongated sporidia; or go on branching and
rebranching. Each mature sporidium throws out a lateral
process, which unites with a similar process of the nearest
sporidium (i.e., two sporidia coalesce or conjugate). After
conjugation, they become detached from the pro-mycelium,
and either germinate, producing secondary sporidia, or
produce mycelial hyphz. The secondary sporidia are also
capable of germinating, and either give rise to tertiary
sporidia, or they may produce a ramifying mycelium
bearing a large number of sporidia of the first and second
order. The secondary and tertiary spores also germinate,
and give rise to short hyphee which bear the first or true
bunt spores.

As the bunt spores of this fungus hibernate in seed
wheat, the wheat plants become affected from the begin-
ning. These spores germinate, and ultimately give rise
to the various sporidia and mycelia (already described)
“on and in the ground.” The last-formed mycelia (from
the secondary and tertiary sporidia) find their way into
the host-plants through the first-formed stomata. When

GRAMINEOUS CROPS. 125

once within the host-plant, the fungus ultimately finds a
resting-place in an ear of corn. Within the grains of
wheat the bunt spores are produced.

This fungus (known as “smut balls,” “ bladder-brand,”
“stinking smut,” etc.) often causes no small amount of
damage to our wheat crops. Tilletia tritici rarely attacks
barley, but is common on wheat.

Prevention.—Bunted grains should not be sown or
drilled.

Cure.—(1) As bunted grains often burst among healthy
ones, and thereby cover (more or less) the latter with
spores, it is advisable for the farmer to “ pickle” his seed
before drilling. By steeping the seed wheat in a 2 per
cent. solution of iron sulphate for three or four hours, the
spores of bunt are completely destroyed. (2) A solution
of copper sulphate has been recommended for the same
purpose ; but it (like many other “steeps ” used by agricul-
turists) often destroys the germinating properties of the
seeds,

The Fusisporium of Wheat (fusisporium culmo-
-yum) attacks the ears of wheat, covering them (more or
less) with a pale yellow-coloured mycelium. This fungus
has a similar life-history to F’. hordei (of barley), which
has already been described.

The Spring Rust of Corn (Puccinia rubigo-vera),
generally known as the “corn mildew,” produces the
familiar red spots (“rust”) on the leaves and stems of
certain genera of the Graminee in the spring, and black
spots (mildew) in the autumn and winter. The first stage
of the life-history of this fungus is termed Uredo rubigo-
vera, and the second, or mildew stage, is the Puccinia
rubigo-vera. The first, or “rust” stage, is common on
‘cereals and certain grasses in the spring months. If an

126 DISEASES OF CROPS.

infested leaf of wheat is examined under a low power of
the microscope, it will be seen covered (more or less) with
sori somewhat similar to those of Puccinia miata (see
Fig. 18 A and B). These sori of a bright-yellow colour
rupture the epidermis of the leaf. If a transverse section
of a small sorus is examined under the higher powers of
the microscope, a mass of oval-shaped spores is easily
discovered, supported on erect hyphal filaments rising
from a densely matted mycelium which passes between
the cells of the host-plant. The yellow spores (uredo-
spores) of this fungus are liberated by bursting the
epidermis of the infested plant. These spores are wafted
about by air currents, and may ultimately fall on the
leaves of wheat plants, where they germinate by giving
rise to hyphae. These hyphe pass into the interior of the
infested plants through the stomata. The production of
mycelia and spores goes on for many weeks.

Later in the season the Uredo spots disappear, and
black spots, belonging to the second stage in the life-
history of this fungus, make their appearance. These
small black spots are the sori of the mature P. rubigo-
vera, and are seen upon an infested wheat-stem. When
these sori are examined under a low power of the micro-
scope they have a similar appearance to those represented
in Fig. 37 B. If a thin transverse section of a small
sorus is magnified 100 diameters, an appearance somewhat
resembling Fig. 18C will be observed. The epidermis
of the host-plant is ruptured at certain points where com-
pound spores (teleutospores) protrude. The teleutospores
are supported on erect (more or less) hyphe rising from
a densely matted mycelium (spawn). The teleutospores
(resting-spores) of P. rubigo-vera are developed in the
autumn, and then hibernate until the following spring.

GRAMINEOUS CROPS. 127

In the spring they germinate on decaying gramineous
plants, giving rise to a short pro-mycelium. The pro-
mycelium produces yellow-coloured spores, which germi-
nate on damp surfaces. These yellow-coloured spores
are said to ultimately give rise to an Aicidiwm fungus
on certain members of the Boraginacce [e.g. Symphytum
asperrimum (prickly comfrey), Symphytwm officinale
(common comfrey), etc.], which also produces spores. The
Aéicidium spores (according to the late Dr. De Bary! and
. other authorities) reproduce (on certain cereals and
grasses) the Uredo, or the “rust” stage, of P. rubigo-vera.

This fungus infests wheat, barley, rye, as well as
certain grasses.

Prevention.—(1) A good system of land drainage lessens
the attacks of this fungus. (2) According to Mr. W. G.
Smith, F.L.S., “It is now generally accepted as a fact
amongst practical men, that after dressing the land with
farmyard manure and nitrate of soda mildew often puts
in a strong appearance; but after mineral manures, bone
superphosphate, and bone meal drilled with the seed,
rust and mildew are much less apparent. There can be
no doubt that farmyard manure has a tendency to produce
a gross soft growth in corn which is suitable for fungi,
and that mineral manures, on the contrary, have a ten-
dency to produce a firm, stiff growth unsuited for rust and
mildew.” (3) Seeds from infested plants should not be
drilled. (4) It would be well for farmers to burn mil-
dewed straws, as this material (when used as litter) is a
suitable medium for the teleutospores to hibernate in.
The author has experimentally shown that certain fungal
spores are capable of hibernating for months, in farmyard

1 Neue Untersuchungen tiber Uredineen, ii. (1866).

128 DISEASES OF CROPS.

manure, without losing their vitality (Chemical News,
vol. 49, p. 279).

Cure—(1) Lands which have grown infested crops
should be treated with quicklime or gas-lime. (2) A top-
dressing of iron sulphate (4} to 1 cwt. per acre) in the
spring destroys the early stage of P. rubigo-vera.

The Summer Rust of Corn (Puccinia graminis,
Fig. 45). The Uredo, or early stage, of this fungus makes
its appearance in the summer, usually about July. Un-
like the “spring rust,” the “summer rust” produces
pallid spots (sori) on the leaves and culms of corn and
grass plants. The early or rust stage is known as Uredo
linearis (the specific name referring to the elongated
form of the sori); and the second or mildew stage as
Puccinia graminis. The sori of the mildew stage are
black, and make their appearance in the autumn and
winter. The sori of the rust stage of this fungus are not
unlike those of Puccinia coronata (see Fig. 37 A and B).
If a transverse section of a small rust sorus is examined
under the microscope, a mass of oval-shaped spores will
be observed, supported on hyphe rising from a closely-
packed mycelium which infests the host-plant (Fig. 45 A).
These spores (uredospores) rupture the epidermis of the
host-plant, and thereby greatly interfere with its life-
history. In fact, the fungus causes disease, by obtaining
nourishment from the protoplasm and sap of the living
cells of the infested plant, as well as causing no incon-
siderable amount of damage by rupturing the epidermis.
After liberation, the uredospores may fall on the leaves of
wheat and other cereals, where they germinate by giving
rise to hyphe which pass into the interior of the host-
plant through the stomata. The hyphe reproduce the
uredo-mycelium with its accompanying spores. During

GRAMINEOUS CROPS. 129

the early autumn the uredo-mycelium produces blackish
Spores, and when these spores are massed together they
give rise to the well-known sori of the corn mildew. The
wheat stem and leaves become covered (more or less) with

Fig. 45.—Tare Summer Waeat Miupew (Puccinia graminis).

A. A section of a portion of asorus of Uredo linearis (the early stage of P.
graminis) x 195.
B. A section of a portion of a sorus of Puccinia graminis (later stage) x 195.
C. Germinating teleutospore. x 490.
D. Uredospore (1), Teleutospore (2), Pro-mycelium spore (3). x 490.
black disease spots belonging to the Puccinia, mildew,
or perfect state of this fungoid growth. If a transverse
section (Fig. 45 B) of one of the disease spots (sori) is
examined microscopically, a mass of two-celled spores
(teleutospores) will be observed. The teleutospores, like
the uredospores, are supported on erect hyphe rising
from a compact mycelium embedded in the tissues of the
K

130 DISEASES OF CROPS.

host-plant. The teleutospores (the “ resting-spores ” of
Plowright) hibernate until the following spring. They
then germinate (Fig. 45 C), and subsequently give rise to
a short pro-mycelium bearing transparent oval-shaped
spores of a yellow colour. According to De Bary
(Monatsbericht der Ktniglichen Preuss. Akademie der
Wissenschaften zu Berlin, 1865), Plowright (British
Uredinee and Ustilaginew), Carruthers, Sachs, and other
botanists, the pro-mycelium spores of this fungus germi-
nate on the leaves of Berberis vulgaris (the common
barberry bush) giving rise to the fungus known as
Acidium berberidis, whose spores are said to reproduce
the uredo-mycelium, or the first stage in the life-history
of Puccinia graminis. On the other hand, Cooke,
Berkeley, Smith, and others state that there is no genetic
connection between Puccinia graminis and Atcidium
berberidis, and that these fungi are quite distinct. If
the latter idea is correct, the pro-mycelium spores must
germinate (without producing an cidiwnt) on various
members of the Graminew, reproducing the uredo-
mycelium and its spores.

According to De Bary’s school of fungologists, the
“summer corn mildew” completes its life-history by
alternately living upon two separate plants; it is, there-
fore, a dimorphic, hetercecious, or metcecious fungus. Mr.
Plowright (see his book, loc. cit.) states that forty-seven
hetercecious species of the Uredinee are now known, and
the life-history of eleven of these was first worked out by
himself.

It is well known that parasitic mildews cause putre
factive changes to occur within the tissues, etc., of infested
plants. The author detected the presence of small quan-
tities of alcohol and lactic acid in the sap of infested or

GRAMINEOUS CROPS. 181

mildewed wheat plants (Chemical News, vol. 58, p. 255).
These compounds may be produced from the decomposi-
tion of glucose which is always present (more or less) in
the sap of healthy plants.

Prevention.—(1) As the “mildew of corn” requires
moisture for its growth, corn-growing lands should be
well drained. (2) Farmyard manure containing infested
straw should not be applied to land required for cereals;
as the straw (which formed the litter) contains the teleu-
tospores of Puccinia graminis. In fact, it would be well
to destroy mildewed straw. (3) Mr. W. Carruthers, F.R.S.
(Journ. Roy. Agric. Soc. [2nd series], vol. xviii., p. 495),
states that “the farmer should not permit the barberry
to have a place in hig hedges or in plantations on his
farm.” (4) Seed from mildewed corn crops should not
be drilled—as Mr. Smith has shown that the disease is
hereditary. “It exists in a finely-attenuated state in
seeds taken from diseased plants, and can be transmitted
in a long interminable line from generation to generation.”
(5) Clearing hedges of “rusted and mildewed grasses”
is an important preventive against the attacks of this
farm pest.

Cure.—(1) The author has shown (Chemical News, vol.
58, p. 255; and Journ. Chem. Soc., 1886, -p.'119) that
iron sulphate destroys the wheat mildew and its spores
in both stages of their life-history. The author’s in-
vestigations have been completely and entirely confirmed
by Mr. G. W. Edgson (Journ. Chem. Soc., 1886, p. 114),
M. Delacharlonny (Biedermann’s Centralblatt fiir Agric.
Chemie, vol. xviii.), Professor Quantin (Journ. de lV’ Agric.,
1888), M. Gaillot,) and others. Therefore, it is advisable

1 Directeur de la Station Agronomique de Béthune (Pas-de-Calais).

132 DISEASES OF CROPS.

for farmers to top-dress wheat crops with iron sulphate
in the proportion of } to 1 cwt. (per acre) mixed with 5
times its weight of dry earth. (2) As it is possible that
“living spores or niycelium may sometimes be present
outside the seeds,” it would be well for farmers to steep
seed wheat in a 2 per cent. solution of iron sulphate for
three or four hours. This reagent destroys the spores,
etc. M. Chavée-Leroy says: ‘‘The recent experiments in
France prove conclusively that the use of iron sulphate
preserves cereals from mildew.”

CHAPTER V.
THE DISEASES OF MISCELLANEOUS CROPS.

(1) THE PARASITES OF ASPARAGUS (Asparagus officinalis).

The Asparagus Beetle (Crioceris asparag?) is about
a quarter of an inch in length, with a body of a blue-
black colour. The yellowish elytra are adorned with a
central black cross and black spots. The dark-coloured,
oval eges are deposited by the female beetle on the
flower-buds of asparagus plants. The larve are “ short,
fleshy, and dingy grubs; with six short legs and a double
series of fleshy tubercles along the lower surface of the
abdominal segments, which also serve as legs.” These
grubs, having previously eaten the leaves and soft shoots
of the host-plants, retreat to the earth, where they spin a
cocoon in which they change to the pupal stage. In about
sixteen days the pup are transformed into perfect insects.
There are several broods of this insect during the season
(June to September).

M. Lucas (Annales de la Société Entomologique de
France, 1888) recently discovered two natural enemies
of Crioceris asparagi. One is the Calocoris chenopodii
(belonging to’ the Heteroptera), which sucks the juices
from the larve of the asparagus beetle; while the other

_is an internal parasite (Myobia pumila). The pupe of
this Tachinid fly is transformed into the perfect insect

within the skins of the Crioceris larvee.
133

134 DISEASES OF CROPS.

Prevention.—(1) Sprinkling the plants with soot causes
both larvee and beetles to make a retreat from the as-
paragus beds. (2) Syringing the infested plants with
warm water has also been recommended for the same
purpose. (3) Dressing asparagus beds in the spring with
salt and quicklime greatly lessens the attacks of this pest.

Cure.—(1) In the United States “ Paris green” (the
poisonous copper arseniate) has been effectually used as
a remedy against the attacks of C. asparagi. The “ Paris
green’”’ is suspended in water (2 Ib. to 40 gallons), and the
asparagus beds are watered with 40 gallons of the mixture

Fig. 46.

per acre (Riley’s Insect Life, vol. i. p.110, and The
Fourth Report of Entomological Commission, U.S.A.,
p. 143). (2) The author has found that a small quantity
of crude or commercial naphthalene placed along the rows,
followed by syringing the infested plants with cold water,
completely destroys both the larvee and beetles.

(2) THE PARASITES OF CABBAGE (Brassica oleracea)
AND ALLIED CROPS.

(a) The Large White Butterfly (Pontia brassicae,
Pieris brassice), These butterflies “ hover over the beds
of cabbages and lay their eggs on the leaves, The eggs
are small yellowish bodies (Fig. 46 A) somewhat re-

MISCELLANEOUS CROPS. 135

sembling the fluted sugar-loaves of the grocers’ windows.
After the eggs have remained on the leaves for a few
days, the little caterpillars break out of them and proceed
to their work of destruction upon the tender leaves of the
cabbage. They eat voraciously, soon piercing the paren-
chyma of the leaves with a thousand holes, and often
completely destroying nearly the whole crop of oleraceous
plants (cabbages, broccoli, cauliflowers); and rendering
the plants disgusting by the quantity of their excrements”’
(Dallas). The hairy caterpillars are more or less green
or yellow, with black spots (Fig. 46 B). They are pro-
vided with mouths well adapted for masticating or chew-
ing hard substances, hence the damage done to cabbages
and similar plants. The caterpillars change their skins
three times, when they retire to some quiet spot and there
turn to green-coloured pupe (Fig. 46 C). “The butterfly
comes out in about a fortnight from the midsummer brood
of chrysalids (pup), but not till the following spring from
the chrysalids that form in the autumn.” The perfect
insect or butterfly has four white wings. The mouth is
purely suctorial, and is provided with a spiral trunk fitted
for drinking up the juices of flowers. Fortunately for
farmers and market gardeners, there are two natural foes
of P. brassice belonging to the Ichneumonide. Both
Microgaster glomeratus and Pteromalus brassice lay
their eggs in the larve and pupe respectively of P. bras-
sic. The eggs of the former parasitic fly turn to small
larvee which feed “ on the fat of their host, who, bad luck
to him, goes on eating faster than ever. Retribution,
however, must come in time, and when the cabbage-eater
should turn into a chrysalis, the parasitic guests are
thinking of changing too, so they burst through the skin
of their host, and leave him to perish.” Pteromalus bras-

136 DISEASES OF CROPS.

sicee lays its eggs within the pups of Pontia brassice.
After the hatching of the eggs the parasitic larve feed on
the contents of the pupze.

Prevention.—(1) Brushing infested plants so as to dis-
place the caterpillars, is a means of preventing further
injury. Before brushing, a small quantity of crude naph-
thalene should be placed round each plant. This prevents
the caterpillars from returning up the stems. (2) Dredg-
ings of sulphur and salt over infested plants have been
recommended for keeping off the attacks of this pest. (3)
Good cultivation and a liberal dressing of the most suitable
manures “has been found serviceable; and the application
of liquid manure will save a crop even when badly
infested.”

Cure.—(1) Probably hand-picking is the most effectual
remedy. ‘Children should be encouraged to catch the
butterflies (as well as the caterpillars) and crush them,
and not be blamed for killing the ‘poor little pretty
butterflies.’ ‘Handsome is that handsome does,’ and the
converse to this is, in the same sense, equally true,
‘Ugly is that ugly does.’” (2) Syringing the plants with
weak solutions of salt, soap-suds, or lime is said to destroy
these caterpillars. (3) Watering the crops with a solution
of iron sulphate (2 per cent.) destroys the larve of Pontia
brassice, and is beneficial (as a plant-food) for cabbage
plants. (4) Inthe United States kerosene emulsion has
been used for destroying the larvee of the cabbage butter-
fly (Riley’s Insect Life, vol. i. p. 27).

The Small White Butterfly (Pontia rape, Pieris
rape) and The Green-veined White’ Butterfly
(Pontia napi, Pieris napi). The eggs of both these
butterflies are laid singly on the underside of the Jeaves
of cabbage plants. The larve of these butterflies are both

MISCELLANEOUS CROPS. 137

of a green colour. Those of Pontia rape have rows of
yellow spots along each side, while those of Pontia napi
are of areddish hue. The pupe of P. rape are a fleshy-
brown colour, spotted with black, while those of P.
napi are pale green or yellow with brown tips. The
perfect insects measure about two inches across the
wings. The anterior wings of the “Small White” are
white with blackish tips, and two black spots on each
wing. The posterior wings are white above and yellow
below. The anterior pair of the ‘“Green-veined” are
white with greyish tips and veins, There are also two
black spots nearly in the centre of each wing. The under
surface of the anterior wings is yellow with darker veins
and spots. The posterior wings are white above and
lemon-yellow below with greenish-coloured veins. P.
brassice, P. rape, and P. napi all feed upon turnips as
well as cabbages. .

Prevention and Cure.—See those already recommended
for Pontia brassice.

The Turnip Moths, already described, also attack
cabbage plants.

The Cabbage Moth (Mamestra brassice) vies with
the cabbage butterflies in the injury which it does to
oleraceous plants. The moths are of a brown colour, and
the anterior wings are marked with black streaks. The
posterior wings are brown with a greyish base. The eggs
are laid on the leaves, where they are hatched in four or
five days. The larvee (which feed upon the host-plants)
are green, with dusky stripes on the back, and dingy
yellow ones on each side. When fully grown, the larvee
are about an inch and a quarter in length. They turn to
the pupal stage in the earth, where they hibernate until
the following summer.

138 DISEASES OF CROPS.

Prevention.—Previously infested lands should be treated
with gas-lime. This destroys the brown pupe and pre-
vents any mischief beingdone during the following season.

Cure.—(1) Hand-picking (by children) is one of the
mos teffectual remedies. (2) Poultry eat the pups, and
are therefore of service in clearing the ground of this pest.
(3) Soot, salt, and sulphur are useful top-dressings.

The Great Yellow Underwing Moth (Noctua
pronuba) belongs to the Noctuide, a group of the Lepidop-
tera, which are chiefly nocturnal in their habits, The moths
make their appearance in June; and are known by the
dark-brown anterior and yellow posterior wings. The
eggs are laid on certain plants in July. The larva,
known as surface caterpillars, are nocturnal — feeding
during the night and hiding under clods, etc., during the
day. When mature, the larve measure about one and
three-quarter inches long, and the colour of the integu-
ment varies from sage-green to brown. There is a dark-
brown band along the back, while the under side is of
a pale-green colour. The larvw feed during the autumn,
and hibernate beneath clods of earth, etc. In the spring
(after feeding for a short time) these larve construct
earthen cells, in which they turn to red pupe. The pupe
are transformed into moths in June or July.

Prevention,—(1) Burn such weeds as bittersweet and
docks, as the caterpillars of N. pronuba feed on these
plants as well as on the varieties of cabbage.

(2) The rook, jackdaw, chiff-chaff, blue-tit, and other
insectivorous birds destroy these farm pests.

Cure.—Gas-lime, tobacco-water, soft-soap, lime, soot,
quassia, quicklime, and sulphur have been prescribed as
remedies.

The Boll Worm (Heliothis armigera), which is the

‘

MISCELLANEOUS CROPS. 139

larva of one of the Noctuidae, causes considerable damage
to the cotton, corn, leguminous, oleraceous, and other crops
of the United States. It is only found toa very limited
extent in the south of England. For further information
see Dr. Riley’s Fourth Report of Entomological Commis-
sion, U.S.A., pp. 355-381, and Insect Life, vol. i. p. 831.

The Cabbage Plant-Louse (Aphis brassice) is one
of the so-called “ green flies,” and has a somewhat similar
life-history to those already described. These aphides
“do much harm by inserting their suckers in the plants
and drawing away the juices; and also causing a much
deformed and diseased growth.”

Prevention.—A. good system of cultivation, and a liberal
use of the most suitable manures, is a means of lessening
the destructive powers of this insect.

Cure.—(1) Top-dressings of lime, soot, and sulphur are
recommended as remedies. (2) Drenching the infested
plants with a solution, containing one part of ammoniacal
or gas-liquor and twelve of water, completely destroys
the cabbage aphis. (3) Solutions containing tobacco,
soft-soap, and quassia, are said to have a like effect. (4)
Manuring the land with a top-dressing of iron sulphate
(2 cwt. per acre) has a tendency to produce a luxuriant
growth, and after this treatment the plants are rarely
attacked by this injurious insect.

The Crane Fly (Tipula oleracea). The grubs, called
leather-jackets, of this insect attack the roots, etc., of the
varieties of cabbages, as well as those of gramineous and
other plants.

Prevention and Cure.—See chapter iv.

The Cabbage Gall Weevil (Ceutorhynchus sulci-
collis) has already been described under ‘ The Parasites of
Turnips.”

140 DISEASES OF CROPS.

The Cabbage Fly (Anthomyia brassicw) and The
Cabbage Root-eating Fly (Anthomyia radicum) belong
to the same genus as, and are somewhat similar to, the
beet or mangel fly already described. The grubs of the
first-named insect injure the cabbage plants, “ by eating
passages in the stem and roots, and sometimes destroying
whole fields of cabbages by subsequent disease, or decay
in wet weather, of the roots and lower part of the stalk.”
The whitish grubs are devoid of legs, and measure about
one-third of an inch in length. The grubs turn to pups
in the earth ; the latter are then transformed into perfect
insects in about twenty days, unless the pupz are formed
late in the season, in which case they hibernate until the
following spring. There are several generations during
the summer and autumn. The grubs of A. radicwm are of
a yellowish colour, and feed in the roots of the cabbage
and other oleraceous plants. The perfect insect has a
slender, pointed abdomen. In this point it differs from
A, brassice, which has a more or less rounded abdomen.

Prevention.—(1) Rotation of crops. Farmers and mar-
ket gardeners should not grow cabbages on the same plots
of land season after season. (2) Dressing the land with
superphosphate of lime has been recommended as a means
of prevention.

Cure.—(1) Lime-water is stated to destroy the maggots
of these two dipterous flies. (2) Lands previously infested
with these insects should be treated with gas-lime or
quick-lime.

Clubbing in Cabbages (Plasmodiophora brassice)
has already been described in chap. iii. Some agricul-
turists and entomologists still believe that clubbing in
cabbages and other brassicaceous plants is due to the
attacks of insects (!). This is a mistake, for true club-

MISCELLANEOUS CROPS. 141

bing is undoubtedly due to a fungus belonging to the
Myxomycetes. On the other hand, certain wart-like
excrescences are produced on the roots of turnips and
cabbages by a small weevil (Ceutorhynchus sulcicollis) ;
but these outgrowths are quite distinct from the true
club-root.

Prevention and Cure.—See under the heading of ‘ The
Parasites of Turnips.”

The-Mould of Cabbages (Peronospora parasitica)
belongs to the same genus as the potato-disease fungus,
and has a somewhat similar life-history. The mycelium,
which is provided with haustoria (suckers), infests the
interior of the leaves of cabbages, and produces con-
idiophores (bearing conidia), which pass through the
stomata on the under surface of the leaves. The patho-
logical action of this fungus is to produce putrefactive
changes in every part of the leaf which comes in contact
with the mycelium. The conidiophores (unlike those of
Peronospora infestans) have a tendency to twist, and
therein agree with another fungus, P. ganglioniformis,
described later in this chapter. The conidia of the “‘ cabbage
mould” germinate on various cruciferous plants ; and, like
P. infestans, this cabbage fungus produces odspores (rest-
ing-spores) of a yellow-brown colour, which hibernate for
several months. P. parasitica is common in the summer
and autumn.

Prevention.—(1) Destroy all the stumps of previously
infested crops. (2) The farmer or market gardener should,
as far as possible, destroy shepherd’s purse, whitlow grass,
pennycress, coral root, hairy bittercress, and many other
weeds, for both the odspores and the mycelium of this
fungus are to be found on these plants, as well as on cab-
bages and turnips.

142 DISEASES OF CROPS.

Cure.—See those already described for destroying P.
infestans (the potato-disease fungus).

The Fusisporium of Cabbages (Fusisporium
aurantiacum) has a similar life-history to F. solani

Fig. 47.—Wsuirre Rust Funeus or Cappaces (Cystopus candidus).

A. Mycelium bearing conidia. x 195.
B. Conidium (zoésporangium) producing zodspores. x 405,
C. Odgonium (1) and antheridium (2). x 196.
D. Odspore (resting-spores), x 195.
K. Inner membrane of odspore containing zodspores. x 195.
F. Zodspores. x 405.
band f, Zodspores germinating.
(Magnifications according to Zeiss.)

already described. It infests the leaves and stems of
the host-plant.

The White Rust of Cabbages (Cystopus candidus,
Fig. 47) causes no inconsiderable amount of damage, in
certain seasons, to cabbages, cauliflowers, and allied crops.
This disease is known by the swollen leaves, stems, etc.

MISCELLANEOUS CROPS. 148

(of infested plants), which become marked with elongated
white spots. The mycelium of C. candidus lives amongst
the intercellular spaces of the host-plant; and, like that
of Peronospora parasitica, is provided with haustoria
(suckers). When a white spot or sorus of Cystopus is
examined under the microscope, chains of oval-shaped
conidia are seen rising from an embedded mycelium (Fig.
47 A). The granular protoplasm of each conidium gives
rise, on a damp surface, to a number of secondary spores
(zodspores) provided with cilia (Fig.47B). After a time
the cilia disappear. The zodspores germinate and repro-
duce the mycelium and its accompanying conidia and
secondary spores. By the continual reproduction of the
mycelium and zodspores, the disease is propagated from
leaf to leaf and from plant to plant. The mycelium of
Cystopus also gives rise to antheridia and odgonia (Fig.
47 C), or male and female organs respectively. After
fertilization, each odgonium produces odspores, %.c., rest-
ing-spores (Fig. 47 D). Before the odspores are ripe
several months must elapse, and the ripening process goes
on within the tissues of the host-plant. In fact, the fer-
tile odspores hibernate until the following spring, when
they “germinate on the ground during wet weather.”
The protoplasm of the odspores gives rise to zodspores
(Fig. 47 E and F), which ultimately reproduce the ‘ white
rust” mycelium, and its accompanying conidia on the
young leaves, etc., of cabbages and allied plants. “No
doubt the little motile zodspores are carried through
moist air by currents of wind, and distributed in every
direction throughout the country.”

Prevention.—(1) Destroy, as far as possible, cruciferous
weeds, especially shepherd’s purse. (2) Destroy all in-
fested stumps, etc. (3) Rotation of crops tends to lessen

144 DISEASES OF CROPS.

the ravages of Cystopus and other parasitic fungi. (4)
Top-dress the land (when the plants are young) with half
cwt. of iron sulphate mixed with 5 to 10 times its weight
of sand or dry earth per acre. This dressing prevents
the attacks of “ white rust,” and is most beneficial as a
plant-food.

Cure.—Water the infested plants with a solution of
iron sulphate (1 to 5 per cent. solution) at the rate of 2 or
3 gallons per acre.

(8) THe Parasites or CELERY (Apium graveolens).

The Celery Stem Fly (Piophila apti). The larve
of this dipterous fly feed within the stems and leaf-stalks
of celery plants. The cream-coloured larve are devoid
of legs, and turn to pup# within the host-plants. The
thorax and abdomen of this fly are black, while the head
is of a brown colour. P. apit is about half an inch across
the extended wings, which are almost colourless. The
fly makes its appearance in May, and there are two broods
during the year.

Prevention.—(1) Destroy infested stems. (2) Top-
dress the young plants with soot or a mixture of slaked
lime and. soot.

The Celery Leaf Miner (Tephritis onopordinis)
has already been described as a “ parasite of parsnips.”

The Red Rust of Celery (Puccinia apii). The
early stage of this fungus is known as Uredo apit, or
“ red rust’; and the later stage as Puccinia api, or the
“black mildew” of celery. The fungus is allied to, and
has a somewhat similar life-history to, Puccinia graminis
already described.

Prevention.—(1) As Dr. M. C. Cooke proved the disease
to be hereditary, seeds from infested plants should not be

MISCELLANEOUS CROPS. 145

sown. (2) As far as possible, all umbelliferous weeds
should be destroyed.

Cure.—See those under the heading of Puccinia gra-
minis.

The Celery Mildew (Puccinia heraclet), like the
preceding fungus, belongs to the Uredineew. It some-
times infests celery plants,

Prevention.—(1) Destroy all umbelliferous weeds, espe-
cially cow-parsnip (Heracleum sphondylium), and wild
chervil (Anthriscus cerefolium). (2) Sow perfectly
sound seeds.

(4) THE Parastres oF CucuMBERS (Cucumis sativa).

The Cucumber Eelworms (Tylenchus cucwmeris ?)
belong to the Anguillulide, or ‘‘thread-worms.” They
are said to destroy the roots and rootlets of cucumber
plants. :

The Cucumber Thrips (Thrips cucumeris?) often
causes considerable damage to cucumber plants. It be-
longs to the same genus as Thrips cerealium already
described.

The Cucumber Root Fungus (Ustilago cucumeris,
Fig. 48) was discovered by the author infesting the roots
and rootlets of Cucumis sativa.1 During the summer of
1887, Mr. E. F. Crocker (a market gardener, of Ham
Green, Bristol) sent the author a large number of the
roots of cucumber plants, with “ peculiar knot-like
bodies ” upon their external surfaces (Fig. 49); and from
a quantitative estimation of the nitrogen contained in
these “ swellings,” and in the roots proper, the author was
at first inclined to believe in the hypothesis of Dr.

1 Proceedings Royal Society of Edinburgh, vol. xv. p. 403.
L

146 DISEASES OF CROPS.

Tschirch, applying to the outgrowths on the roots of
Cucumis. Tsthirch (Berichte der Deutschen Botanischen
Gesellschaft, Heft 2, 1887), in describing the root-tuber-
cles found in the Leguminose, stated that most probably
they were storehouses for nitrogenous compounds—these
compounds being subsequently used up in the ripening
of the seed. On submitting the nodules, roots, etc., of

Fig. 48.—Root or CucumBER

Infested with one of the Ustilagines, causing nodular out-growths.
Nat. size.)

Cucumis to chemical analysis, the following percentages
of albuminoids were obtained :—

I. I, IL.
Albuminoids (nitrogenous substances) in nodules 20-24 19:96 20-51
in roots (without nodules) . . . 1:92 2:00 206
instemsand leaves . . . . . 3:21 3:24 3:30

Although the analyses appeared to support Tschirch’s
idea, it was soon discovered by a microscopical study of
the roots, that the nodular outgrowths, were due to a
parasitic fungus belonging to the Ustilaginee, or the same

MISCELLANEOUS CROPS. 147

group of which the “smuts” are important members.
Fig. 49 represents a transverse section of a root with
nodule. In very thin sections under high power, the
nodules are seen to be filled with hyphe and spores. The
spores of this fungus are more or less v-shaped, and are
formed by division of the protoplasmic contents of the
hyphal filaments which ramify in the root-tissues of the
host-plant. Unlike most of the members of the Ustila-
gine, the hyphee of Ustilago cucwmeris! are not divided

Fig. 49.—TRaNsvERSE SECTION OF A Root wita NoDvue.
8
(Under low power.)

by transverse septa. The hyphe (which are many times
thicker than the cell-walls of the adjacent tissues) pass,
cell by cell, through the cortex of the rootlet, and some-
times across the intercellular spaces (Fig. 50). Branching
of the hyphe is well marked in the tissues of the nodules,
and sometimes they send out lateral branches which end
abruptly in the cells. The protoplasm of the nodular cells
after a time becomes vacuolated (Fig. 50) and filled with
spores. The spores of the cucumber-root fungus are
found in the soils (where Cucumis sativa has been grow-
ing) in the autumn and early winter, having been liber-

1 Originally described as Ustilago cucumis,

148 DISEASES OF CROPS.

ated by the rotting of the root-nodules. These spores
retain their vitality for months, and are then capable of
attacking the new seedlings planted in such soils. The
Spores are easily disseminated by such agencies as air,
soils, and streams. Ustilago cucwmeris produces a diseased
condition of the whole plant.

Prevention.—(1) Avoid growing cucumber plants in the
same soil season after season. (2) Sow only good healthy
seeds,

Qa

2 budding
ps spores
Wahi] Muctetes aruven
is to celle wale,

ve

Fig. 50.—Sprorr Formation.
x 713,

Cure.—Water the infested plants with a 4 per cent.
solution of iron sulphate. The iron sulphate completely
destroys the fungus, but does not injure the host-plant.
Mr. E. F. Crocker (already mentioned) has been successful
in destroying the said fungus by using iron sulphate. He
wrote the author as follows : —‘I planted the present house

1 Proceedings Royal Society, Fdinburgh, vol. xv. p. 410.
2 Ibid., p. 409.

MISCELLANEOUS CROPS. 149

of cucumbers in the second week in August (1887), and
have used the iron sulphate. I find no trace of disease,
although the plants were diseased when I first wrote to
you in August. I have been able to cut scores of fruits of
the most splendid quality, and they have been extraordi-
narily fruitful. - It is the first house of cucumbers I have
grown without disease for at least ten years.” }

(5) Tue Parasites or Hops (Humulus lupulus).

According to Linnzus (Linnei Amenitat. Academ. vii.
p- 452) hops were brought to Europe by the Goths from
Asiatic Russia. Whether this be true or not, their proper
cultivation in this country only dates from 1524.2 Hops
require a rich, deep soil, and should be grown on freshly
broken, well drained, and highly manured land.

The Hop Aphis (Phorodon humuli), “ green fly,” or
“hop blight,” is too well known among hop-growers to
require anything more than a general description. ‘The
genus Phorodon, to which it belongs, is distinguished from
others of the Aphidine by the horns (antenne) being
hardly longer than the body, together with the lowest
joint being toothed or gibbous, and the tubercles‘on the
forehead each having a strong tooth.” Dr. C. V. Riley?
was the first entomologist who conclusively proved that
P. humuli hibernates upon damson, plum, sloe, and other
trees of the genus Prunus. He says in Insect Life, vol. i.
p. 184: “Hibernating at the present season of the year

1 A Treatise on Manures, p. 302.
2 Houghton’s Husbandry and Trade Improved, vol. ii. p. 457 (a.D.
1727}.
3 Gardeners’ Chronicle, Oct. 27th, 1887; Insect Life, vol. i. pp. 70
‘and 133.

150 DISEASES OF CROPS.

(winter), the little glossy, black, ovoid eggs of the species
are found attached to the' terminal twigs, and especially
in more or less protected crevices around the buds of
different varieties and species of Prunus, both wild and
cultivated. From this winter-egg there hatches a stem-
mother, which is characterized by somewhat stouter and
shorter legs and honey tubes than in the individuals of
any other generation. Three parthenogenetic! genera-
tions are produced upon Prunus, the third becoming
winged. This last is what Lichtenstein called the
‘ pseudogyna’ or migrant; and it instinctively flies to the
hop-plant, which is entirely free from the attack during
the development of three generations upon Plum. A num-
ber of parthenogenetic generations are produced upon the
hop-plant until in the autumn, and particularly during
the month of September, winged females are again pro-
duced. This is the ‘pupifera’ of Lichtenstein, or return
migrant; and she instinctively returns to the plum. Here
she at once settles, and in the course of a few days,
according as the weather permits, produces some three or
more young. These are destined never to become winged,
and are true sexual females. Somewhat later, on the hop-
plant, the true winged male, and the only male of the
whole series, is developed; and these males also congre-
gate upon the plum, on the leaves of which, toward the
end of the season, they may be found pairing with the
wingless females which stock the twigs with winter-eggs.

Each parthenogenetic female is capable of pro-
ducing on an average one hundred young, at the rate of
one to six per day. Hach generation begins to breed

1 Parthenogenesis is a term applied to ¢ function of those females
who produce fertile eggs without previous impregnation.

MISCELLANEOUS CROPS. 151

about the eighth day after birth, so that the issue from a
single individual easily runs up, in the course of the sum-
mer, to trillions. . . . Therefore a single stem-mother
may, under favouring circumstances, blight hundreds of
acres in the course of two or three months.”

Prevention.—(1) Trees belonging to the genus Prunus
should be thoroughly washed with lime in both the
autumn and spring. (2) The natural enemies of the
Aphides are the larve of the Coccinellide (the “ lady-
bird ” beetles).

Cure.—The most effectual remedy used in this country is
a decoction of soft-soap and tobacco (20 Ibs. of soft soap to
100 gallons of water, and then 3 Ib. of tobacco added). Mr.
Whitehead, F.L.S., says that “the cost of washing varies
from thirty to thirty-five shillings per acre each time it is
done. Great care must be taken to wash every leaf under-
neath, and the process generally must be repeated twice
or even thrice.” ‘Washing is done by means of a large
garden-engine, fitted with a pump, and a long length of
gutta-percha hose on each side, having a single jet, or
rose, or spray syringe, which can be directed under the
leaves and round the bines, thoroughly cleaning the
plants” (Ormerod). But undoubtedly the best machine
for this and similar purposes is the Pneumatic Distributor
or Strawsonizer invented by Mr. G. F. Strawson, of New-
bury. In this machine both liquid and solid insecticides
are distributed by means of a blast of air “‘ produced by
a fan actuated by the travelling wheels of the machine,
and worked up to a velocity of 8,600 revolutions per
minute.”

The Hop Flea (Haltica concinna) belongs to the
same genus as, and is somewhat like, the ‘‘turnip fly.”
The hop flea, or beetle, causes considerable damage, in the

152 DISEASES OF CROPS.

spring, by piercing the shoots; and, later in the season,
the white larve feed on the “cones,” etc., of the hop-
plant. The eggs are deposited in the cones, bine, or
under the cuticle of the leaves; and when laid in the
summer they are hatched in about twelve days. The
beetles are of a greenish-black hue, “ with a brassy tint,’
and the elytra are dotted. According to Mr. Whitehead,
“these flea-beetles hibernate in the perfect state in ths
ground close to the hop-hills, or in the hollow dead bines
left on the stocks, or in the pieces lying on the ground
near them.”

Prevention.—(1) Top-dress the young sian with lime
or soot. (2) Good cultivation and a generous use of
manures. The application of nitrogenous and phosphatic
manures has been recommended.

Cure.—(1) In the United States a solution of white
arsenic (arsenious oxide), in the proportion of 1 lb. to 200
gallons of water, is used for destroying the hop-flea
(Riley’s Insect Life, vol. i. p. 76). (2) In the same
country a dilute solution of Paris green has also been
used for the same purpose. ‘ American entomologists
wonder that we do not employ arsenic in England as an
insecticide. Paris green has been used in America more
extensively than any other substance. As a wash, about
a pound is put into 100 gallons of water. When used
dry, dusted on as a powder, about one pound is put to
thirty pounds of flour or gypsum, and about twenty
pounds distributed over an acre” (Whitehead).

The Hop Frog Fly (Eupteryx picta, or “ jumpers”)
belongs to the same genus as the potato frog fly already
described. It is a small yellowish-green insect spotted
with black. It punctures the leaves, bines, etc., of the
hop-plants to extract the juices.

MISCELLANEOUS CROPS. 153

Prevention.—Destroy nettles and other weeds. Clean
cultivation is essential for the growth of hops.

Cure.—See the remedies recommended for the “hop
aphis ” and the “ hop flea.”

The Hop Bug (Lygus umbellatarum) also sucks
the juices from various parts of the hop-plant. It be-
longs to the Hemiptera (plant-bugs), and is about a
quarter of an inch in length. The elytra are of a
reddish colour.

Prevention.—A thorough cleansing of the land after
the harvest greatly reduces the attacks of this injurious
insect.

Cure.—Syringing and dusting the vines with the in-

secticides already mentioned destroy Lygus as well as
other hop-pests.
' The Pale Tussock Moth (Dasychira pudibunda),
The larva of this moth is known as the “hop-dog.” It is
of a straw-colour, and the incisions between some of the
segments are deep black, like velvet. “On the fifth to
the eighth segments there are dense yellow tufts on the
back. On the twelfth segment a longer dull red tuft
appears.” The larve (each about 1} inch long) feed on
the leaves of hops and of various trees. In the autumn,
while on the hop-plant, they spin a slight cocoon, in which
they turn to the pupal stage. The pup are transformed
into moths the following May.

Prevention.—Destroy the cocoons by hand-picking, etc.

Cure.—Syringe the hop-vines with the insecticides
already mentioned.

The Ghost Moth (Hepialus humuli). The larve of
this moth infest the roots of hop-plants. They are of a
cream colour with brown heads, and measure about two
inches in length when fully grown. They turn to pupe

154 DISEASES OF CROPS.

in the ground. According to Mr. Whitehead they are
rare.

Prevention.—A thorough cleaning of the land is essen-
tial, as the larve of Hepialus feed on the roots of the
common nettle, burdock, and other weeds.

Cure.—In Germany crude naphthalene has been used
with marked success. A small quantity of this substance
is placed round the stocks of the vines.

The Hop Snout Moth (Hypena rostralis) is about
an inch across the extended wings, and is known by the
snout-like appendage of the head. The larve are of a
green colour, and feed upon the leaves of the hop-plant.
They pass the pupal stage on the leaves.

Prevention and Cure.—See those recommended for the
“ hop frog fly ” and the “ hop aphis.”

The Hop Wireworm (Elater lineatus) is the larva
of the “striped click beetle.” The beetle is somewhat
like E. obscurus (Fig. 36 B), but is distinguished from the
latter species by having the elytra striped with grey-
coloured lines. The larve of E. lincatus attack the new
shoots of the hop-plants.

Prevention and Cure.—See under the head of “ Click
Beetles” in chapter iv.

The Red Mite (Tetranychus telarius)—the so-called
“red spider ’+-differs from the true spiders by having the
head, thorax, and abdomen all in one piece. It belongs to
the same genus as another “red spider” (7. bioculatus)
which threatens serious mischief to the plants of the
newly-made tea plantations of Assam. 7. telarius causes
considerable damage to hops, particularly in dry seasons.
The leaves of the hop-plants “turn brown, become
shrivelled, and fall off.”

Cure.— Mr. Whitehead recommends ‘washing the

MISCELLANEOUS CROPS. 155

plants with soft soap and water, or even with pure water,
as a remedy for these mites. Washing the plants with
‘ sulphur-water ’ is also an effectual remedy.”

The Hop Mildew (Podosphera castagnei). This
fungus attacks the hops of England, France, Germany,
Austria, Belgium, Holland, and the United States. It
“frequently destroys the crop of hops entirely in some
grounds; and this is often accomplished with wonderful
celerity. A few mildewed cones may be noticed in a
plantation ; and before the crop is ripe, or can be picked,
the whole may be reduced to mere blackened lumps of
rubbish by the work of the fungus.” P. castagnei belongs
to the group Ascomycetes, and De Bary (Vergleichende
Morphologie und Biologie der Pilze) refers it to the
division Erysiphew. Therefore it is closely allied to the
pea mildew (Erystphe Martit) described in chapter ii.,
and has a somewhat similar life-history.

Prevention.—(1) Destroy dandelion, groundsel, daisy,
and other weeds belonging to the Composite, as Podo-
sphera lives upon these plants, as well as upon hops. (2)
“Hop bines from infested plants should be burnt, in order
to destroy the resting-spores upon them.” (3) Mr. White-
head recommends dressing the land with quicklime or
soot after an attack of mildew. (4) Avoid planting “ sets”
from mildewed plantations ; but if infection is suspected,
the “sets” should be dipped in a solution of iron sulphate
(2 per cent. solution).

Cure.—(1) A solution of iron sulphate has been used
in France? as a remedy for the vine-disease caused by
Oidiuwm Tuckeri (the vine mildew). As the vine mildew

1 The spores are in an ascus.
2 Bulletin de la Société Agronomique (Gironde), 1888.

156 DISEASES OF CROPS. —

is allied to the hop mildew, a solution of iron sulphate
might prove a cheap remedy for this pest. The solution
could easily be distributed by the Strawsonizer. (2) Sul-
phur has long been employed for destroying the hop mil-
dew. From 45 to 65 lbs. of “ flowers of sulphur” per acre
should be distributed, if possible, in hot and dry weather.
The sulphur should be distributed by means of the Straw-
sonizer. For the distribution of insecticides and fungi-
cides on ground crops, as well as hops, vines, etc., there
is no better machine than the Strawsonizer or Pneumatic
Distributor.

(6) Tue Parastres or Lerruces (Lactuca sativa and
Lactuca altissima).

The Lettuce Fly (Anthomyia lactuce) is allied to
the onion fly already described. The female lays her eggs
amongst the flowers, and when hatched the larve feed on
the seed.

Prevention.—(1) Burn the refuse from infested crops.
(2) Infested seed should be cleared from “the pupe or
little brown fly-cases ” of this parasite.

The Lettuce Root Fly (Aphis lactuce), as its name
suggests, seeks the juices of lettuce roots. It is of a
yellowish-green colour, and measures about one line in
length. The attacks of the insect are recognised by “ the
plants drooping suddenly without any evident cause.”

Cure.—(1) “ Drenching the ground round the lettuces
with strong soap-suds, soap-suds and tobacco-water, and
lime-water” is recommended for this purpose. (2) A
dilute solution of crude carbolic acid has also been recom-
mended for the same purpose.

The Heart and Dart Moth (Noctua exclamationis)

MISCELLANEOUS CROPS. 157

The larvee of this moth (already described) feed on the
roots of lettuces.

The Lettuce Mildew (Peronospora ganglioniformis,
Fig. 51) produces pallid patches on lettuce leaves, and “in
bad cases summer lettuces are quickly reduced to pu-
trescent masses.” The conidiophores of this fungus are

Fig, 51.—Lerrucr Mrnpew (Peronospora ganglioniformis).
‘ A. A conidiophore and conidia.

B. Oospores ec ona
x 196 diam. (Zeiss’s C. and 3 oc.).

flattened and slightly twisted (Fig. 51.A). Each terminal
branch has a cup-like expansion bearing on minute
spicules from three to five conidia. The conidia germinate
upon the leaves and give rise to mycelia within and upon
the host-plant. Like Peronospora parasitica and other
species of the Peronosporee, the lettuce mildew produces
oospores (Fig. 51 B) which hibernate “in the old rotting

158 DISEASES OF CROPS.

stems of lettuce plants which have been destroyed by the
fungus.”

Prevention.—(1) Burn infested lettuce stumps, etc. (2)
Destroy groundsel, nipplewort, corn sowthistle, and other
weeds,

Cure.— Water infested plants with a solution of iron
sulphate (2 per cent, solution).

(7) THE PARASITES OF THE TomaTo (Lycopersicwm
esculentunr).

The Tomato Eelworm (Tylenchus sp.?), like the
various “eelworms” already described, belongs to the
Anguillulide. It attacks the roots and rootlets of L.
esculentum.

The Dodder (Cuscuta trifolvi), already described as
a parasite of clover, attacks tomato plants.

Prevention and Cure.—See chapter ii.

Peronospora infestans also attacks L. esculentum,
especially when grown out of doors.

Prevention and Cure.—See the treatment of the potato
disease in chapter iii.

Chlorosis of Tomato Stems and Leaves. Tomato-
growers are well aware that the leaves and stems become
spotted or blotched. This is not due to the attacks of
fungi or insects, but indicates imperfect nutrition.

Prevention and Cure.—Use dressings containing kainit,
nitrate of soda, superphosphate of lime, and iron sulphate.

CHAPTER VI.
CONCLUDING REMARKS.

As we have dealt with many micro-objects in the fore-
going chapters, a few details concerning the microscope
and its accessories may be interesting and useful to those
who may wish to study in a practical manner the various
objects mentioned in this book.

The Microscope.—For the investigation of parasitic
fungi and farm insects a good microscope is essential ; and
there are several manufacturers in England and on the
Continent who make instruments that are well adapted
for such work. The microscopes of Carl Zeiss, of Jena
(whose instruments are sold by C. Baker, of 243, Holborn,
London), are strongly recommended for students and others
who are desirous of purchasing first-class instruments.
Zeiss’s large microscopes are suitable for the complete
investigation of all the organisms mentioned in the fore-
going pages. Messrs. Beck, of 68, Cornhill, London, and
Messrs. Powell and Lealand, of 170, Euston Road,
London, are also manufacturers of good microscopes. A
suitable cheap microscope is made by Zeiss at about £3.
All the higher objectives are available with this instru-
ment (No. vii.), on account of the fine quality of the
micrometer movement. Beck’s “star” microscope is also
a good cheap instrument.

The Objective is the most important part of the
159 i

160 DISEASES OF CROPS.

microscope, and it is necessary to have good lenses to
do satisfactory work. The powers chiefly required for
the entomological portion of the subjects herein treated
are the following :—

Zeiss’s Objectives. English Objectives.
a. or 3 inches focal distance.
aa. ” 1 ” ”

b. ” goo ”
Cc. ” 4 a) ”

These lenses magnify from about 20 to 250 linear dia-
meters with the lowest eye-piece (A, or No.1). For the
examination of fungi and diseased vegetable tissues (in
addition to the above objectives) Zeiss’s E and H, or an
English 4 inch and ;, inch, are necessary. To make out
the nuclei and cilia of the smallest zodspores, etc., it is
essential to be provided with a still higher power, such
as Zeiss’s ~; oil-immersion lens, which the author can
thoroughly recommend. It has a perfect definition, and
everything there is to be seen can be made out with this
lens.

The Eye-piece.—Zeiss’s Huyghenian eye-pieces Nos.
1, 3, and 5, or the A, C, and D of English makers, are very
useful for the economic biologist.

Illumination.—Daylight is the best light to use for
the study of parasitic fungi and other transparent objects.
But in the winter and for opaque objects (small beetles
and other insects) a paraffin lamp is essential. ‘The one
thing requisite in a lamp is that the flame is steady; this
depends on the wick fitting properly.” For the examina-
tion of opaque objects it is necessary to be provided with
a stand condenser.!

1 A description of the stand and sub-stage condensers will be found
in manuals devoted to the microscope.

CONCLUDING REMARKS. 161

Section Cutting.—Sections of infested leaves, stems,
roots, etc., may be cut either by hand with a hollow-
ground razor, or with the microtome. When cut by hand-
the specimen is imbedded in a soft cork or a piece of pith.
The razor is dipped in dilute alcohol and then drawn
diagonally across the piece of pith (containing the speci-
men) with a steady sweep. Before cutting each section
the razor should be dipped in dilute alcohol. “Great care
is required, in cutting sections by hand, to hold the razor
firmly yet lightly, so as to cut them thin and at the same
time even, and this cannot be done without a great deal of
practice.” A much easier method of cutting sections is
by using a microtome. Zeiss’s microtome is everything
that could be desired for cutting vegetable sections. It
consists of a round glass plate, borne by two pillars on a
heavy brass foot, on which the knife or razor is worked
by hand. The specimen to be cut is imbedded in a brass
tube and pushed up through an opening in the plate by a
screw with divided head. The divisions of the head indicate
the thickness in hundredths of a millimetre =0:03937 inch.

Hardening Vegetable Sections.—As it is neces-
sary to harden many vegetable substances, this can be
done by placing them in dilute alcohol (1 part water to 2
parts methylated spirit). The materials to be hardened
should be left in this mixture about 24 hours, then trans-
ferred to pure methylated spirit for about 12 hours, when
they are ready for cutting and mounting.

Mounting Sections. — Microscopic sections are
usually mounted on glass slides (8x1 in.), either dry or
immersed in some fluid, and covered by a thin glass slip.
Small animal parasites may be quickly killed by immers-
ing them in alcohol; after a time take them out, dry

them, and, if transparent, they may be at once mounted in
M

162 DISEASES OF CROPS.

Canada balsam or glycerine. If opaque, they should be
mounted in Canada balsam. Both animal parasites and
sections of infested plants can be mounted in water or
dilute glycerine when not required as permanent objects.
If, on the other hand, sections of infested plants are to be
permanently mounted, the best preservative media are
glycerine jelly and Canada balsam.

Concerning the methods of using the microscope, section
cutting, hardening, staining, and mounting objects, the
author refers his readers to the undermentioned books :—

Carpenter’s The Microscope and its Revelations.

Frey’s Mikroskop und die Mikroskop Tecknik.

Beale’s How to Work with the Microscope.

Griffiths and Henfrey’s Micrographic Dictionary.

Hogg’s The Microscope, etc.

Martin’s Manual of Microscopic Mounting.

Marsh’s Section Cutting. Davies’s Practical Microscopy.

Naégeli and Schwendener’s The Microscope in Theory
and Practice,

Duval and Lereboullet’s Manuel du Microscope.

The scope and object of the present work necessarily
prevent the author from writing at length upon the above
subjects; but it may be mentioned that a good pocket
magnifier is indispensable for the working economic bio-
logist. In conclusion, “the microscope is an instrument
imperative to all who would cultivate their minds by the
possession of a store of interesting facts and rank well as
intelligent beings in society.” In economic biology, or
the biology of the farm, it is indispensable as an auxiliary
to the scientific inquirer into the causes and effects of the
diseases of farm crons.

INDEX.

Abortion in cows, 96, 106.
Abortive florets, 117.
Acherontia atropos, 49.
cidium berberidis, 127, 130.
Agar-agar, 42.
Agriculturists and plant diseases,

7.
Agrostis stolonifera, 119.

53 vulgaris, 119.
Aira cespitosa, 95.
Allium cepa, 40, 42, 44.

» schenoprasum, 46.
Amebe, 74.
Anbury, 72.
Anguillulide, 17, 118.
Antenne, 5.
Antheridia, 23, 44, 52, 53, 54, 142.
Anthomyia bete, 33, 39.
brassicae, 140.
ceparum, 40.
coarctata, 117.
lactuce, 156.
at radicum, 140.
Anthoxanthum odoratum, 85.
Anthriscus cerefolium, 145.
Aphida, 64, 149.
Aphides, 6.
Aphidius avene, 77.
Aphis, bean, 9:
Aphis brassice, 139.
faba, 9.

» floris-rape, 63, 64.
Aphis, grain, 77.

Aphis granaria, 77, 84, 99, 103,

107.
Aphis, hop, 149.
Aphis lactuce, 156.

» rapa, 63, 64.
Aphis, turnip, 63.
Apion flavipes, 31.
Apionide, 31.
Apium graveolens, 144.
Aptera, 4.
Arachnoidea, 67.
Arpuranot, 110.
Arsenic, 152.
Artificial fertilizers, 62, 158.
Asci, 29, 59, 106.
Ascomycetes, 155.
Asparagus beetle, 133.
Asparagus officinalis, 133.
Assimilation, 29, 44, 48, 72.
dthalia spinarum, 69.
Avena elatior, 95.

s» fatua, 117.

» flavescens, 95.

+ pubescens, 95.

», sativa, 99.
*¢ Awnless,” 115.

Bacterium allii, 41.

Baxer, J. G., 55.

Barberry bush, 130.
Barley, Fusisporium of, 81.
parasites of, 77-83.
smut of, 83.

”

”

163

164

INDEX.

Bastian, Dr. H. C., 118.
* Battledore,” 115.
Bean aphis, 9, 63.
», beetle, 12.
», beetles and foreign seed, 13.
» brand, 16.
» mildew, 16.
» parasites of, 9-16.
Bean-root fungus, 14.
Bean weevils, 14.
Bees, humble, 12.
Beet carrion beetle, 35, 40.
Beet-leaf rust, 36.
Beetroot, parasites of, 33-36.
Beetroots, nematoids of, 36.
Bent grass, 119.
Berberis vulgaris, 130.
“ Bere,” 115.
Berxewey, Rev. M. J., 51, 53,
97, 130.
Bernarp, M., 93.
Beta maritima, 39.
» vulgaris, 39.
Béte de la Vierge, 64.
Black-fly, 9.
Blacks, 70.
Bladder-brand, 125,
Blue-tit, 78, 138.
Boll worm, 138.
Bombus terrestris, 12.
», lucorum, 12,
Book, object of, 1.
Books on microscope, 162.
Boraginacee, 127.
Brassica oleracea, 134,
” rapa, 61,
Broom, 22.
Bruchus granarius, 12.
“ pisi, 26.
Brush-harrow, 83.
Buckwheat, as manure, 34, 36, 91.

Buckwheat beetle, 83.
‘5 eelworm, 83.
5 parasites of, 83-84.

Bunted grains, 125.

Bunt of wheat, 124.

Burning refuse, 44, 45, 46, 47, 48,
56, 58, 61, 67, 90, 95, 101,
116, 120, 188, 158.

Butterfly, green-veined, 136.

+ large white, 134.
5 small white, 136.

Cabbage fly, 140.
ee gall weevil, 139.
yy moth, 137.
» mould of, 141.
3 parasites of, 134~144.
ss plant-louse, 139.
root-eating fly, 140.
Catbapes, clubbing in, 140.

i Fusisporium of, 142.

rr white rust of, 142.
Calandra granaria, 102, 107.

n oryz@, 102.

» palmarum, 102.
Calocoris chenopodii, 133.
CaLwer, Dr., 84.

CarLyLe quoted, 76.
Carpels, 23.
Carrot fly, 36.

» Mmilliped, 38.

s» moths, 38.
Carrots, parasites of, 36-39.
CarruTHers, W., 119, 130, 131.
Cecidomyia destructor, 111.

‘a tritici, 116.

Celery leaf miner, 144.
» mildew, 145,
» parasites of, 144-145.
» red-rust of, 144,
», Stem fly, 144.

INDEX.

165

Cellulose, 2.

Cephus pygmaeus, 80, 99, 107.
Cerostoma xylostella, 67.
Ceutorhynchus sulcicollis, 65, 139,

141.

“* Chaff-red,”’ 115.
Cuaviée-Leroy, M., 132.

Chives, 46.

Chlorophyll, 2.

Chlorops teniopus, 78, 80, 107,

113,

Chlorosis, 158.

Chromogenic fungus, 98.

Chrysomelida, 48.

Cilia, 48, 53, 74.

Claspers of Hessian fiy, 113.

Claviceps purpurea, 96, 103, 104.
5 an Wilsoni, 96.

Clean cultivation, 66, 75.

Click beetles, 88.

Clover dodder, 20.

» eelworms, 17.

>» mildew, 22.

1, parasites of, 16-24.

“+ Clover-sickness,”’ 17, 19, 22,

24,

Clover weevils, 16.

» white worms of, 20.
Clubbing of turnips, 72.
Club-root, 40.

Coccinellide, 64, 151.
Cockchafer, 86, 110.
Cocksfoot grass, 95.
Celinius niger, 80.
Coleoptera, 5, 86, 110.

*« Colliers,” 9.

Colorado beetle, 48.
Comfrey, 127.

Composite, 155.
Conceptacles, 29, 105, 106.
Concluding remarks, 159-163.

Conidia, 22, 28, 46, 48, 52, 58,
71, 81, 97, 100, 104, 141, 142.
Conidiophores, 22, 23, 44, 48, 52,
58, 141.
Conjugation, 101.
Continental clover seeds, 22.
Convolvulacee, 20.
Cooxg, Dr. M. C., 96, 130, 144.
Copper arsenite, 49.
», sulphate, 57, 83, 85, 100,
101, 125.
Corn fly, ribbon-footed, 78.
» moth, 110.
» Sawfly, 80.
» thrips, 108.
1 weevil, 107.
Coronated mildew of grass, 94.
Cow-parsnip, 39.
Crane fly, 84, 139.
Crested dogstail, 95.
Crioceris asparagi, 133.
Crocker, EK. F., 145, 148.
Cruciferous weeds, 62, 75.
Cucumber-root fungus, 145.
¥ thrips, 145.
Cucumbers, parasites of, 145-149.
Cucumis sativa, 145, 147.
Cultivation, good, 44, 85, 90, 95,
109, 139.
Cure for clover-sickness, 20.
“ Curl,” 51.
Curtis, Dr. J., 14, 46, 67, 70, 121.
Cuscuta trifolii, 20.
Cynosurus cristatus, 95.
Cystopus candidus, 142.

Dactylis glomerata, 95.
Daddy long-legs, 84, 139.
Datuas, W. S., 135.
Dandelion, 34.

Darnel grass, 95.

166

INDEX.

Darwi, C., 7, 55.

Dasychira pudibunda, 153.
Death’s-head moth, 49.
DeBary, Dr., 51, 127, 130.
DeECanpo.ze, A., 14, 83.

Deep ploughing, 81,117.

Deep trenching, 44.
DetacHartonny, M., 57, 93, 131.
Depressaria cicutella, 38.

3) daucella, 38.

“9 depressella, 38.
Devarine, Dr., 18, 118.
Diamond-back moth, 67.
Dimorphic fungus, 130.

Diptera, 5, 99, 112, 140.

Disease-proof potatoes, 55.

Diseases of gramineous crops,
77-132. ,

Diseases of leguminous crops,
9-32,

Diseases of miscellaneous crops,
133-158.

Diseases of root crops, 32-76.

Docks, 83, 138.

Dodder, clover, 20, 58.

Downy oat grass, 95.

Draining the land, 20, 85, 94, 95,
98,106, 109,120, 124, 127, 131.

Drosophila flava, 67.

Ear-cockles in wheat, 118.
Early sowing of cereals, 115.
Eneson, G. W., 15, 181.
Eelworm, buckwheat, 83.

9 of grasses, 85, 103.
Eelworms, clover, 17.

me onion, 40.

‘ vitality of, 18.
Elateride, 88.
Elater lineatus, 88, 154.

» obscurus, 88, 154.

Elater sanguineus, 88.

>» sputator, 88.

Elytra, 26, 31, 48.
Enchytreus Buchholzii, 20.
Ephedrus plagiator, 77.
Ephestia kukniella, 110.
Ergot, 96.

» a variety of, 96.
Ergoted fodder, 106.
Ergotism, 96, 106.

Ergot, prevention of, 96.
Erysiphe graminis, 95, 121.
es Martii, 16, 28, 29.
Etton winter beans, the, 15.
Eupelmus karschii, 114.
Eupteryx picta, 152.

r solani, 51.
Euryscapus saltator, 114.
Eye-piece, the, 160.

Eyes of insects, 5.

False wireworms, 14, 38.
Farmyard manure, 30.
Fertilization, 54.
Festuca elatior, 95, 119.

» pratensis, 95.
Finger-and-toe, 72.
Fiorin grass, 119.

Firing stubbles, 116, 117.
“ Flax-seed,”’ 113, 116.
Fly, onion, 40.
1», parsnip, 47.
», turnip, 61.
Foreign seed, bean beetles and,
13.
Fowuer, Rev. Canon, 110.
Frit fly, 99.
Frog fly, potato, 51.
Fungi, parasitic, 2.
1» Saprophytic, 2.
Furze, 22.

INDEX. 167

Fusisporium aurantiacum, 142.

a5 culmorum, 125.

* hordei, 81, 96, 125.

* lolii, 96.
Fusisporium of barley, 81.

5 of rye-grass, 96.

Fusisporium solani, 58, 81, 142.

Gattot, M., 93, 131.
Garlic rust, 45.

Gas-lime, 27, 47, 66, 69, 81, 85,
88, 90, 116, 118, 121, 128, 138,

140.

Gas-liquor, 88, 139.
Gemmation, 101.
Ghost moth, 153.
Glumes, 118.
Glyceria fluitans, 96.
* Golden drop,” 115.
** Golden melon,” 115.
“ Gotteslammchen,” 64,
Gout fly, 78.
Grain aphis, 77, 84.
Grapholitha pisana, 25.
Grass blight, 95.
Grass-culm smut, 94.
Grasses, eelworm of, 85.

Pe infested, 80.

re parasites of, 84-98.
Grass weevil, 86.

Great yellow underwing moth,

138.
Green manuring, 91, 121.
Green-veined butterfly, 136.

Grirritus, A. B., 15, 36, 54, 56,
66, 75, 82, 92, 98, 101, 102, 122,

131, 134, 145..

Hakcket, E., 74.
Hair grass, 95.
Hairy bittercress, 141.

Haltéres, 99, 114.
Haltica concinna, 151.

+ memorum, 61,
Halticide, 61.
Handpicking, 50, 69, 8 , 136,

“138, 153.
Hardening sections, 161.
Hardy varieties of potato, 54.
Harxer, A., 20.
Harvest bug, 67.
Haulm fly, 78.
Haustoria, 28, 141, 143.
Havenstein, Dr., 17.
Heart and dart moth, 68, 156.
Heliothis armigera, 138,
Hemiptera, 4, 5.
Henbane, 56.
Hepialus humuli, 153.
Heracleum sphondylium, 145.
Hermaphroditism, 5.
Hesperida, 91.
Hesperia linea, 91.
Hessian fly, 111.
Hetercecious fungus, 130.
Heterodera Schachti, 36.
Heteroptera, 133.
Holcus lanatus, 86, 114.
Homopterous insects, 64.
Hop aphis, 149.

+ bug, 153.

+ flea, 151.

» frog fly, 152.

sy Mildew, 154.

snout moth, 154.

Hops, parasites of, 149-156.
Hop wireworm, 154.
Hordeum distichum, 77.
Humble bees, 12,
Humulus lupulus, 149,
Hymenium, 60.
Hymenoptera, 80.

168

INDEX.

Hypena rostralis, 154.
Hyphe, 2, 24, 28, 45, 47, 48, 52,
53, 60,101, 122, 124, 126, 128.

Ichnewmenide, 77, 135.

Infested grasses, 80.

“4 ey analysis of, 123.

Insecta, 4.

Insectivorous birds, 69, 85, 88.

Insect life, phases of, 4.

Insects, eyes of, 5.

» mouths of, 5.
+ Oviparous, 6.
1 Ovo-viviparous, 6.
» reproduction of, 6.

Intercellular spaces, 53.

Irish potato fungus, 59.

Iron sulphate (a fungicide), 16,
22, 29, 44, 56, 58, 72, 83, 85,
92, 93, 94, 95, 96, 101, 102,
107, 122, 124, 125, 128, 131,
136, 139, 144, 148, 155, 158.

Isaria fuciformis, 96.

JENSEN, J. L., 101, 102, 121.
JouuiE, M., 93.
Julus londinensis, 120,
»» pulchellus, 14.
» terrestris, 38, 120.
“ Jumpers,” 152.

Kainit, 20, 55, 158.
Kerosene, 136.

Kiln drying of seeds, 108,
“«Kinver,” 115,

“« Knopf,” 104.

Kny, 14.

Kian, Dr., 17, 18, 20, 83.

Lactuca altissima, 156.
» sativa, 156.

Lady-birds, 64.

Lamsin, Pror., 93.

Large white butterfly, 134.

Larval stage of a fungus, 122.

Lawes and GiLBeErT, 19,

Leather jackets, 84, 139.

Leguminous crops, diseases of,
9-32,

Lepidoptera, 5, 138.

Leptinotarsa decemlineata, 48.

Lettuce fly, 156.

» mildew, 157.
»» root fly, 156.

Lime, 27, 28, 37, 41, 51, 66, 71,
78, 116, 136, 138, 139, 144,
152.

Lime-water, 140.

Liming the land, 50.

Linpeman, Dr. K., 27, 112, 113.

Linnzvs, 149.

Lolium perenne, 95.

» temulentum, 95.

Lucas, M., 133.

Lucerne, parasites of, 24-25.

Lycopersicum esculentum, 158.

Lygus umbellatarum, 153.

Matrieaq, 14.
Mamestra brassicae, 137.
Mangel fly, 39.

~ 4, leaf-rust, 40.

_Mangel-wurzel, parasites of, 39-

40.

“ Marienkifer,” 64.

“ Marienkuh,”’ 64.

Mason, J. E., 114.

McQUEEN, 93.

Meadow fescue, 95.

Medicago lupulina, 30.
‘5 sativa, 24,

Meenry, M., 67, 117.

INDEX.

169

Melitot, 29.

Melolontha vulgaris, 86, 110.

Merisus intermedius, 114.

Meicecious fungus, a, 130.

Microbe of onions, 41.

Microgaster glomeratus, 135.

Microscope, the, 159.

Mildews, analysis of, 2.

Mildew of grasses, 94.

Milliped, carrot, 38.

Millipeds, snake, 14.

Milliped, wheat, 120.

Mineral manures, 127.

Monera, 74.

Montaeng, M., 51.

Moss in pastures, 91.

Mould of cabbages, 141.

Mounting sections, 161.

Mount, W. G., 63.

Mouth of insects, 5.

Mucorini, 44.

Mucor subtilissimus, 44.

Monro, Dr., 57.

Murray, A., 5, 49.

Musca coarctata, 117.

Mycelia, 2, 24, 28, 44, 46, 48, 51,
56, 58, 59, 71, 73, 81, 96, 98,
101, 104, 122, 124, 125, 126,
128, 143.,

Myobia pumila, 133.

Myzxomycetes, 73, 141.

Nageett, 14.

Naphthalene, 134, 136, 154.
Nematoid of beetroots, 36.
Nematoids, 17, 36.

Néron, M., 93.

Nettles, 22.

Neuroptera, 5.

‘‘ Niggers,” 70. :
Nitrate of soda, 34, 37.

Noctua exclamationis, 67, 156.
+» pronuba, 138.
» segetum, 67.
Noctuide, 138, 139.
Nomenclature, 6.

Oats, parasites of, 99-102.
Objective, the, 158.
Object of book, 1.
OxrcumicHen, M., 20, 83.
Oidium abortifaciens, 105.
sy Balsamii, 71.
Oidium-conidia, 105.
» mycelia, 105.
Oil-cake for wireworms, 91.
Oligochete, 20.
Onion eelworms, 40.
» fly, 40.
» mildew, 43.
>» mould, 44.
Onions, parasites of, 40-46.
1 putrefactive microbe of, 41.
>. smut of, 44,
Odgonia, 23, 44, 52, 58, 54, 142,
143.
Odspore, 23, 24, 44, 48, 51, 54,
142, 143.
Ormzrop, Miss, 17, 50, 63, 91,
109, 111, 113, 151.
Orthoptera, 4.
Oryza sativa, 102.
Oscinis frit, 99, 107.
» vastator, 99.
Oviparous insects, 6.
Ovipositor, 70.
Ovo-viviparous insects, 6.
Owen, Srp Ricuarp, 6.

Pale tussock moth, 153.
Pallaside parenchyma, 52.
Panicle of grass, 98.

170

INDEX.

Papilio machaon, 39.
Paraffin oil, 26, 27, 37, 41, 91,
108.
Paraphysis, 59, 60.
Parasites, 3.
o of asparagus, 133-134.
3 of bean, 9-16.
a of barley, 77-83.
¥6 of beetroot, 33-36.
* of buckwheat, 83-84.
‘ of cabbage, 134-144.
- of carrots, 36-39.
Pr of celery, 144-145.
* of clovers, 16-24.
5 of cucumbers, 145-149.
of hops, 149-156.
‘5 of lettuces, 156-158.
*% of lucerne, 24-25.
4a of mangels, 39-40.
‘5 of oats, 99-102.
= of onions, 40-46.
oe of parsnips, 45-48.
of pea, 25-30.
— of potatoes, 48-61.
a of rice, 102-103.
¥ of rye, 103-107.
iy of tomato, 158.
as of trefoil, 30-32.
a of turnip, 61-76.
+ of vetches, 32.
“5 of vine, 1, 155.
ee of wheat, 107-132.
Parasitic fungi, 2.
Paris green, 134, 152.
Parsley, 48.
Parsnip fly, 47.
>» leaf miner, 46.
» mildew, 47.
» moths, 47.
Parthenogenesis, 150.
Parus ceruleus, 78.

Pastinaca sativa, 46.
Pastures, moss in, 91.
Pea beetle, 26.

»» mildew, 28.

»» Yooth, 25.

» mould, 29.

1» weevils, 26.
Peas, maggoty, 25.
“ Peerless white,” 115.
Pennycress, 141.
‘“‘ Peppercorns,” 118.
Periola tomentosa, 58.
Perithecia, 29, 95.
Peronospora exigua, 24.

5 ganglioniformis, 157.

“3 infestans, 40,51, 158.

a nivea, 47.

<i parasitica, 72, 141,
157.

i Schleideniana, 43.

4 trifoliorum, 22.

¥ vicia, 29.
Peronosporee, 29, 43.
Peziza postuma, 59.
Phases of insect life, 4.
Puituies, W., 46.
Phorodon humuli, 149.
Phylletreta nemorum, 61.
Phyllopertha horticola, 83.
Physopoda, 108.
Phytomyza nigricornis, 67.
Pieris brassice, 134.
» napi, 136.
» rape, 136.
Pileus, 59, 60.
Piophila apii, 144.
Pisum sativum, 25.
Plant diseases, agriculturists and,
7.
Plasmodiophora brassicae, 40, 72,
140.

INDEX.

171

Platygaster minutus, 114.
Ploughing, deep, 81, 85, 99, 117.
Prowriaut, C. B., 96, 130.
Plusia gamma, 27, 36, 67.
Poa nemoralis, 85.

x trivialis, 85.
Podosphera castagnei, 155.
Polygonacee, 83.
Polygonum fagopyrum, 83.
Pontia brassice, 134, 136.

» napi, 136,
1, rape, 136.
Potato, a disease-proof, 55.
y». fungus, Irish, 59.
» ‘sets, 56.
» Smut, 57.
Potatoes, parasites of, 48-61.
Prickly comfrey, 127.
Priuurevx, M., 57.
Primary spores, 100.
Pro-mycelium, 124, 127, 129, 130.
Psila rose, 86,47.
Pteromalus brassice, 135.
* micans, 80.
Puccinia apii, 144,
» coronata, 94, 128.
» fabe, 16.
1 graminis, 128.
1 heraclei, 145.
» mixta, 45, 126.
1, rubigo-vera, 125.
« Purples,” 118.

Putrefactive microbe of onions, ,

41.

Quantin, Pror., 93, 102, 131.

Quassia, 40, 65, 138.

Quicklime, 20, 39, 81, 85, 102,
-118, 121, 128, 134, 138, 140,
151.

Raver, M., 51.
“Red gum,” 117.
Red mite, 154. .
+, rust of celery, 144.
Removal of infested matter, 56.
Reproduction of insects, 6.
Resting-spore, 23, 30, 44, 46.
Rhynchitis bacchus, 86.
Rhynchophora, 65, 86.
Ribbon-footed corn fly, 78.
Rice, parasites of, 102-103.
+» weevil, 102.
Ruiter, Dr. C. V., 112, 114, 134,
136, 139, 149.
Rirzema-Bos, Dr., 40.
* Rivett’s red,’ 105.
Rolling grass-lands, 85.
Root crops, diseases of, 32-76.
Rostrum of beetles, 31.
Rotation of ‘crops, 41,.66, 75,
140, 143.
Rough stalked grass, 85.
RovssEav quoted, 7.
‘ Riib,” 104.
Rust, beet-leaf, 36, 40.
» garlic, 45.
» spring, 125.
» summer, 128.
», white, 121.
Rutelide, 84.
Bye, ergot of, 104.
» «grass, 95.
» parasites of, 103.

Sacus, J., 130.

Salt, common, 20, 37, 81, 100,
134, 136, 138.

Saprophytes, 3.

Saprophytic fungi, 2.

Savt, M., 38.

Sawfly, corn, 80.

172

INDEX,

Sawfly, turnip, 69.
Saxicola enanthe, 90.
Scarifying, 81.
‘«Scheele’s green,” 49.
Sclerotium, 45, 59, 60, 104.
Secale cereale, 103,
Section cutting, 161.
Semiotellus nigripes, 114.
Sheep's fescue, 95.
SHELDON, Pror., 96.
Shepherd’s purse, 141, 143.
Sreser, Dr., 3.
Silpha opaca, 35, 40.
Silver Y moth, 27, 36, 67.
Siphonophora granaria, 77.
Sitona crinita, 14, 26.
» lineata, 14, 26.
Skip-jacks, 89.
Skippers, the, 91.
Small white butterfly, 136.
Sueruam, A., 85.
Suir, Dr: E., 92.
Sir, W. G., 7, 51, 60, 82, 127,
130, 131. :
‘* Smut balls,” 125.
Smut fungus, 83, 95, 100, 107,
121.
Smut grass-culm, 94.
» of onions, 44,
Snake millipeds, 14.
Soap-suds, 41, 136.
Sodium sulphate, 102.
Soft soap, 40, 108, 151.
Solanum Commersoni, 54, 55,
» immite, 54.
» damesi, 54,
» Maglia, 54, 55.
» tuberosum, 48, 54.
» verrucosum, 54.
Soot, 27, 28, 37, 39, 41, 47, 51,
69, 78, 116, 134, 138, 152,

Sorus, 46, 94, 100, 126, 128, 148.

Sow-thistles, 22, 34, 158.

Spent hops for beans, 13.

Spiny odspores, 54.

Spongy parenchyma, 52.

Sporangium, 45, 73.

Sporidium, 45, 59,60, 105, 106,
124.

Spring rust of corn, 128.

‘« Square head,” 115.

“ Stand-up white,” 115.

“ Steeps”’ for seeds, 102.

“ Stinking smut,” 125.

“ Stock,” 104.

Straw mildew, 121.

Strawsonizer, 57, 63, 151, 156.

Sturnus vulgaris, 85.

Sulphur, 39, 41, 51, 136, 138,

Superphosphates, 140.

Surface mould of turnips, 71.

Swallow-tailed butterfly, 39.

Swaysianp, W., 78, 85, 90.

Sweet grass, 96.

Sweet vernal grass, 85.

Symphytum asperrimum, 127.

ay officinale, 127.
Syringing plants, 26.

Tall fescue, 95.
Tar, 46.
Tares, parasites of, 32.
Tarsi of insects, 5.
TascHENBERG, Dr., 17, 25,79, 84.
Teleutospores, 46, 126, 129.
Tephritis onopordinis, 46.
Tertiary spores, 124.
Tetranychus autumnalis, 67.
oF telarius, 154.
Tetrastichus Rileyi, 114.
Thistles, 34.
Thread-worms, 17.

INDEX.

173

Thrips cerealium, 108, 145.
1» cucumeris, 145.
1 tritici, 108.

Tilletia caries, 124.

» tritici, 124.

Tinea granella, 110.

Tipula oleracea, 84, 139.

Tipulidae, 84.

Tobacco, infusions of, 64, 69;
138, 139, 151.

Tomato eelworm, 158.

» parasites of, 158.
Torsitt, J., 55.

Torrubia, 98.
Torula apiculatus, 101.

» cerevisia, 101.
Transpiration, 29, 44, 48, 72.
Trefoil moth, 31.

», parasites of, 30-32.

» weevil, 31.
Treviranus, 14.

Trichobasis beta, 36, 40.
Trombidium trigonum, 67, 121.
Truffles, 98.

TscarrcH, Dr., 14, 146.
Tubercinia scabies, 57.
Turnip aphis, 63.

» fly, 61, 63.

. gall weevil, 65.

» leaf miners, 67.

»» moths, 67.

» mould, 72.

» roots, analyses of, 66,

75.

» sawfly, 69.
Turnips, clubbing of, 72.

» parasites of, 61-76.

» surface mould of, 71.
Tylenchus allii, 40.

an devastatrix,
99, 103.

18, 85,

Tylenchus Havensteinii, 17, 83, -
99, 103.
i tritici, 118.

Umbelliferous weeds, 145.
Uredinee, 95, 180, 145.
Uredo apii, 144.

» linearis, 127.
Uredo-mycelium, 128.
Uredo.rubigo-vera, 125.
Uredospores, 128.

Urocystis cepule, 44,
Ustilago carbo, 83, 95, 100, 103,
107, 121.

zs cucumeris, 145, 147.

» fabe, 14.

» _ hypodytes, 94.
Ustilaginee, 94, 146, 147.

“ Vache & Dieu,” 64,

Van BENEDEN, 32.

Variety of ergot, a, 96.
Vassaui-Enann1, 109.

Vermes, 4.

Vetches, parasites of, 32.
Vicia faba, 9.

Vine, parasites of, 1, 155.
Vitality of Bacterium allii, 42.
of eelworms, 18, 119.
of Peronospora infestans,

wt

54.

Wauerr, 77, 121.

Warp, H. M., 14, 16.

Weevil, cabbage gall, 139.

corn, 102, 107.

grass, 86.

palm, 102.

rice, 102.

,, turnip gall, 65.

Weevils, 12, 14, 16, 26, 31, 65,
86, 102, 107. ;

174

INDEX.

Wheat blight or rust, 121.

» bulb fly, 117.

» bunt of, 124,

» ear-cockles in, 118.
Wheat-flour moth, 110,
Wheat, fusisporium of, 125.

s midge, 116.

» milliped, 120.

» parasites of, 107-132.

» , thrips, 108.
Warreneap, C., 17, 19, 40, 80,

103, 116, 151, 152, 154, 155.
White rust, 142. .
White-worms of clover, 20.
Whitlow grass, 141.

Wild oat grass, 117,
Wuson, A, §., 96.

Winnowing, 120.
Wireworms, 89, 104, 107.

3 false, 14.
Wood meadow grass, 86.
Woon, Rev. J. G., 84, 86, 87.
Woolly soft grass, 86.
Woronry, Dr., 14, 73.

Yellow bedstraw, 22.
» Oat grass, 95.
Yorkshire fog, 86.

Zeiss, Dr., 52, 142, 159, 160.

Zoésporangium, 142.

Zodspores, 48, 53, 54, 73, 74,
142, 143.

Zygema trifolii, 31.

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