INSECT AND FUNGUS ENEMIES.
The insect enemies of the cauliflower are the same as those which attack
the cabbage and other related plants. The four here mentioned require to
be specially guarded against. In preparing these notes I am indebted to
Mr. L. O. Howard, of the Department of Agriculture, at Washington, for
essential aid.
FLEA BEETLE (_Phyllotrea striolata_, Fabr).--This insect, also
known as the "ground flea" or "Jack," seldom attacks the plants except
while growing in the open ground, and is most troublesome in warm,
sheltered situations. A safe preventive, therefore, is to grow the
plants in beds or frames elevated about three feet from the ground. The
objection to this method, aside from the extra labor involved, is the
necessity of almost daily attention to see that the soil does not dry
out. A supply of water must be conveniently at hand if this method is
used, and it is desirable also, to prevent the beds drying out too
quickly, to have the earth at least eight inches deep. In hot-beds this
insect is seldom troublesome, being probably repelled by the fumes from
the manure used. When the seed is sown in the open ground, as practised
by many large growers, an extra quantity should be used to ensure
against almost certain loss of some of the plants by the flea beetle.
The soil should be rich and fine, so that the plants will pass the
critical stage as quickly as possible. Sowing radish seeds with the
cauliflower is practised by some, as this seed costs but little, and the
radishes, coming up first, are attacked by the fleas, which, to some
extent, saves the cauliflowers. When the fleas appear, almost any kind
of dust will keep them in check somewhat. Lime and ashes are used, but
plaster, which adheres to the leaves better, seems equally good. I have
had good success with rancid fish oil, mixed as thoroughly as possible
with water and sprayed upon the plants. An emulsion made of the oil, in
the same manner as hereafter described for kerosene, would enable it to
be used to better advantage. A decoction of tobacco, or fine tobacco
dust, are standard remedies for this insect.
CUT WORMS.--Cauliflower plants being fully twice as valuable as
cabbage plants, and it being of more importance to have them started at
the proper time, it is necessary to give greater care to protect them
from cut worms. Absolutely clean land contains no cut worms, but such
land is seldom used on which to plant cauliflower. Sod land, which is
generally used, is nearly always full of cut worms. A multitude of
remedies have been proposed for this pest, but few of them are of much
value. The worms are most abundant and destructive in the latitude of
New York during the month of May. Fortunately, cauliflowers are usually
set out either earlier than this, for the early crop, so that they
become well established and out of reach before their depredations
seriously begin, or else, for the late crop, they are set toward the
last of June, after the worms have begun to pupate, and are no longer
troublesome. Until recently, digging and killing the worms by hand
seemed to be almost the only practical remedy. Of late years, trapping
the worms under bunches of grass or cabbage leaves, scattered over the
ground preparatory to setting the plants, has been successfully resorted
to. An improvement upon this method, recommended by the Entomologist of
the United States Department of Agriculture, is now in use, and gives
excellent satisfaction. It consists in poisoning with Paris green the
leaves used to trap the worms, so that there is no need to collect and
kill the worms by hand. A good way to do this is to spray with Paris
green, in the usual way, a patch of young clover, then cut it and
scatter it in small bunches over the cauliflower field a day or two
before setting the plants. For the protection of a few plants in the
garden, an effectual preventive against cut worms is to surround the
stem with a cylinder of paper or tin. This need not touch the plant. One
should expect to lose some plants, however, by cut worms, and be
prepared with good plants to fill the vacancies.
CABBAGE MAGGOT (_Anthomya brassicae_, Bouche)--Dr. J. A.
Lintner, State Entomologist of New York, says of this insect: "This is
probably the most injurious species of the _Anthomyiidae_, as its
distribution is very extensive, both in Europe and America, and it has
shown at times such capacity for multiplication as to cause the entire
destruction of cabbage crops. It commences its attack upon the young
plants while yet in the seed-bed and continues to infest them, in
several successive broods, until they are taken up in the autumn. The
larvae operate by consuming the rootlets of young plants, and by
excoriating the surface and eating into the rind of older ones, or even
penetrating into the interior of the root. When they abound to the
extent of seriously burrowing the stalk the decay of the root frequently
follows in wet seasons, and entire fields are thus destroyed."
The same insect attacks the turnip, cauliflower, and probably other
plants. A closely related species is very injurious to the radish. The
presence of the insect most frequently becomes manifest upon the
cauliflower about two weeks after the plants are set out, and is
recognized by the plants ceasing to grow, and wilting or assuming a
bluish appearance. Such plants should be at once removed, together with
the earth immediately surrounding the root, and fresh plants which have
been held in reserve set in their places. The only satisfactory remedies
are preventive ones. The seed-bed should be composed of soil taken from
the woods, or at least from some place where no cabbages or similar
plants have been grown. But the most important precaution is to avoid
growing the crop year after year upon the same ground, especially after
the insect has made its appearance.
The following remedy, given by Francis Brill, in his pamphlet on
"Cauliflowers," is worthy of careful trial. Mr. Brill says: "The ravages
of the root maggot have made the growing of early cauliflower, and even
early cabbages in many sections, almost an impossibility, but there is a
remedy, when the maggot has attacked the roots of the plants, which may
be known by a tendency of the leaves to wilt and droop in the heat of
the day, very much the same as when affected by club root. Dissolve
Muriate of Potash (analyzing 45 per cent. actual potash) in water in the
proportion of one tablespoonful to the gallon; or double the quantity of
Kainit or common potash salts (13 per cent. actual potash). Apply this
directly to the roots, about one gill to each plant, whether seemingly
affected or not, for the maggot will have done much harm before the
plant will show it, repeating the application as occasion may seem to
require. In sections where these maggots have been prevalent it will be
well to make a solution of half the above strength, and when the plants
are nicely started apply in the same manner as a preventive. Care and
judgment must be used not to overdo the matter, thereby killing the
plants as well as the maggots. Experiment a little at first."
H. A. March, of Washington, says: "The best thing that I have found for
the maggot is a _poor_ grade of sulphur, sulphur before being purified,
that _smells very strong_. Sprinkled over the plants it seems to drive
the fly away."
CABBAGE WORM (_Pieris rapae_, Koch).--The imported cabbage worm,
now known all over the country, is the most troublesome enemy which
attacks either the cabbage or cauliflower, and the most difficult one
with which to deal. It seldom wholly destroys the crop, and is generally
a little less destructive after a few years than it is at first, being
kept in check by its natural enemies. It never disappears, however, and
its numbers cannot be materially diminished for any length of time by
artificial means. Among the partial remedies in use are the following:
1. Catch the butterflies with a net when they first appear in spring,
before they have laid their eggs. This may keep the insect in check for
a year or two when it first makes its appearance, as the butterflies are
comparatively slow fliers, and may be caught without much difficulty by
a spry boy, especially in the morning when the air is damp.
2. Early in the season keep the young plants excluded from the
butterflies, and the whole place free from everything else of the
cabbage tribe, except one or more patches of rutabagas or rape, on which
the butterflies will lay their eggs. This piece is to be then plowed
under.
3. Hand pick the worms from the plants after they are set out, for the
first one or two hoeings, or until the worms become very numerous.
4. Spray with kerosene emulsion, made by using two gallons of kerosene,
one-half pound of common or whale oil soap, and one gallon of water.
Dissolve the soap in the water, and add it, boiling hot, to the
kerosene; then churn, while at least warm, for five or ten minutes, by
means of a force pump and spraying nozzle, until the mixture loses its
oiliness and becomes like butter. When used, dilute one part of the
emulsion with about fifteen of water, and spray it upon the plants by
means of a force pump and spraying nozzle. This emulsion is also
excellent for the cabbage louse and many other insects. In the report of
the United States Department of Agriculture for 1883 may be found a
description and figure of a suitable spraying apparatus.
5. Pyrethrum, one ounce to four gallons of water; or, better still,
mixed one part with about twenty parts of flour and applied while the
dew is on, is an effectual remedy.
6. Hot water, at 130 deg. Fah., will kill the cabbage worms and not injure
the leaves. Boiling water, placed in sprinkling cans and taken directly
to the field, will be about the right temperature by the time it can be
applied. Experiments with a few plants may be needed to enable one to
get just the right temperature to kill the worms and not injure the
plants.
7. Take half a pound of London purple to thirty pounds of finely
pulverized dust of any kind, the finer and drier the better; mix
thoroughly, passing all through a meal sieve. Dash a small pinch into
the heart of the plant, so that it will settle as dust on all the
leaves. Repeat after every rain. Half a pound will serve for one
application over forty acres. Store any that remains in a very dry place
until again wanted.
8. Professor Gillette, of Colorado, finds the best remedy to be Paris
green, thoroughly mixed, one ounce with six pounds of flour, and dusted
lightly over the plants while the dew is on.
FUNGUS DISEASES.
There are several parasitic fungi which are more or less destructive to
the cauliflower at different stages of its growth. The principal
diseases of the cauliflower due to fungi are the following:
STEM ROT.--This is an old disease, which attacks the
cauliflower, cabbage and other vegetables in wet seasons. It has
received various other names, such as "consumption," "humid gangrene,"
etc. Professor Comes,[B] who has studied this disease in Italy, believes
it to be the same as the "humid gangrene" which occurs in Germany, and
which is there attributed to the parasitic attack of the fungus known as
_Pleospora Napi_. He finds this and other fungi present, but does not
himself consider them the direct cause of the disease, which he
attributes solely to the abundance of manure and moisture in the soil,
and an excess of water in the plant, at a time when it is subject to
sudden changes of temperature. Beyond a doubt, however, the real cause
of the disease is the presence of one or more fungi, whose development
is favored by the damp weather. The subject requires further study.
In this country this disease has been reported from Michigan, New York,
Maryland and Florida. On Long Island, in 1889,[C] the cauliflower crop
was almost entirely destroyed by this disease, which was attributed to
the heavy rains at the time the plants were heading. Some fields were a
total loss, and from the best fields many of the heads spoiled before
they reached the market.
No satisfactory remedy is known for the disease. The avoidance of damp
soils and locations would be of some benefit, but is hardly practicable
with the cauliflower. Wide planting is practiced on Long Island in order
to diminish the tendency to the disease. It undoubtedly has this effect
to some extent, by permitting a more free circulation of the air, thus
drying up the moisture on the plants and thereby lessening the
opportunity for the germination of the spores. The increased distance
may also diminish the chance of the spread of the spores from plant to
plant. When this disease appears upon the early crop in hot-beds or cold
frames it may be kept somewhat in check by giving as much air as
possible, and taking care not to apply water to the leaves.
DAMPING OFF.--This is usually due to a species of Pythium (a
fungus closely related to that which causes the potato rot), which
attacks the young plants soon after they germinate. The remedy is, to
give the plants plenty of air until their stems become strong enough to
resist its attacks. An additional precaution sometimes employed is to
grow the plants in pans or small boxes and water them only by setting
these in a tank of water of nearly the same depth, allowing the water to
soak into the soil, but not touch the plants. The disease is seldom
troublesome on plants grown thinly in the open air. If it makes its
appearance, water thoroughly, but not too often, and sprinkle dry sand
over the seed-bed among the plants.[D]
BLACK LEG OR MILDEW.--This is a disease which attacks the stems
of young plants which are being wintered over. It is undoubtedly due to
one or more species of parasitic fungi, but I do not find that the
subject has been studied. Doubtless the rupture of the bark by alternate
freezing and thawing gives the fungi an opportunity to attack the plant.
The disease is prevented and kept in check by keeping the seed-bed dry.
An occasional dressing of sand, lime, wood-ashes or rubbish of any kind,
is useful.
FOOTNOTES:
[B] _Bull. Soc. Bot. France, 1886_ (_Rev. Bib._, p. 128). La cancrena
del Cavolo Fiore (_La gangrene humide du Chou-fleur_) par M. le
Professor O. Comes (_Atti del R. Instituto del incorraggiamento alle
Scienzie naturali._--Estratta dal Vol. IV, 3a serie, degli Atti
Academici, 1885). [The Humid Gangrene of the Cauliflower.]
"A disease which attacks the crops of cauliflower around Resina and at
Torre del Greco, near Naples. The roots of the diseased plants remain
sound, or at least appear so, but the subterranean parts of the stem are
more or less seriously affected; the bark is disorganized, the wood
situated beneath it more or less decomposed, and the pith destroyed for
a variable length. Upon microscopic examination the vessels are found
filled with gum. M. Comes recognizes in this disease all the symptoms of
the affection which has been designated under the name humid gangrene.
He thinks that it is the same disease which, by German authors, is
attributed to the parasitism of _Pleospora Napi_, Fuckel, or to its
conidiferous form, _sporidesmium excitosum_, Kuehn. But he considers the
presence of these parasites as an accessory phenomenon, as well as that
of _Cladosporium_ and _Macrosporium Brassicae_. In his opinion the true
cause of the alteration of the cauliflower is the humid gangrene, that
is to say, a gummy degeneration and putrid fermentation of the tissues,
caused by the abundance of manure in the soil and the excess of water in
the plant at a time when it is subject to sudden changes of temperature.
"This disease is not confined to cauliflowers; it is common in all
garden vegetables, and is of the same nature as that which attacks
tomatoes and which was described by this author in the same journal in
1884." [This disease is also mentioned by Victor Paquet, in his "Plantes
Potagers" (London, 1846, p. 243), where it is attributed to stagnant
moisture].
[C] _Country Gentleman_, 1889, p. 769, (from the _Port Jefferson Times_,
Sept. 27):
"Close upon the heels of a partial failure of the potato crop through
rotting comes the news from various points on Eastern Long Island that
the cauliflower crop has almost totally failed through the same cause.
In Manorville the crop has not sufficiently developed in some of the
fields to warrant picking, and in Mattituck and east of that place the
rotting will result in an almost total loss. In a few cases there is not
yet any indication of rot, but the farmers are afraid to tie the plants
up lest rotting ensue.
"In East Moriches, Orient, and the near vicinity, the yield will not be
of sufficient value to pay for plowing the ground, not to speak of the
other expenses which have been entailed. Through the Hamptons careful
observations failed to reveal scarcely a single successful crop.
"Last Saturday Henry T. Osborn, of East Moriches, tied up 2,000 heads
and on Monday he cut enough to fill 30 barrels. He let them lie in his
barn over night, and the next day not a barrel of them was fit for
shipment to market.
"George Cooper, of Mattituck, planted seven acres of cauliflower which
he thinks will prove a total loss. And so on the reports come from many
East End farmers. The recent heavy rains are generally assigned as the
cause of the failure."
[D] A series of articles upon "damping off" may be found in the
_American Garden_ for 1889, pp. 347-9.