Everglades Station 4imeo Report 56-12 May 17, 1956
RECENT DEVELOPMENTS IN CONTROL OF CABBAGE INSECTS
by JUN 7 1956
W. G. Genung
Several important insects that attack cabbage are harder to kill with
some insecticides than formerly. In some cases development of resistance to a
chemical may be involved. The following examples are given to show what has happen-
ed in the Everglades area, not to attempt to claim resistance, for other factors
may be involved: (1) Over a three year period the imported cabbage worm became in-
creasingly difficult to kill with DDT. The third year populations were as high in
plots treated with DDT as in those receiving no treatment. Control failure was also
observed in growers' fields. (2) Control of cabbage looper with DDT is now barely
satisfactory in the Everglades area under conditions of moderate infestation and is
unsatisfactory under severe infestation. In some sections of the country resistance
by this insect to DDT is definitely claimed. (3) Toxaphene for a number of years
was the second best material for control of serpentine leaf miner. Satisfactory
control of this insect has not been obtained in the past three years with toxaphene.
Whether resistance by insects, changes in manufacturer's formulation or
some other factor beyond the growers control, is involved is immaterial to him.
The result in insect control is the same and his control program must be varied to
cope with existing conditions.
Conditions of application often affect results and insecticides are fre-
quently accused of poor performance when such is not the case. Parathion and other
phosphatics used when the weather is too cold may give inadequate control of aphids.
Endrin, Aldrin and other good cutworm killers when applied to a hot, dry soil mulch
volatilize rapidly, resulting in poor control. Jhen the worms come out to feed the
insecticide is greatly reduced in strength. Failure of sprays to adequately control
insects on cabbage foliage is frequently attributable to lack of a spreader-sticker
in the spray mixture. Combinations of chlorinated hydrocarbon and phosphatic insec-
ticides, if allowed to stand too long in the spray tank, may break down and reduce
effectiveness. A discussion of all the factors that could be considered here, with
the many special instances would constitute a report in itself*
Pre-planting or pre-emergence treatment: (1) A pre-planting or pre-emergence treat-
ment using 2t pints of (-lb. technical) endrin emulsion per 100 gallons of water
per acre is suggested particularly for crops planted after the middle of December.
(2) An application of 35 lbs. of a 20 per cent toxaphene dust or 5 lbso of 40 per
cent wettable toxaphene applied in 100 gallons of water should give comparable con-
trol. These treatments are suggested for a one shot knockout punch
Two pre-planting applications about a week apart (or 1 pre-planting and
1 pre-emergence application) using 2 3 Ibs. of toxaphene 40 per cent wettable
powder, or dieldrin W.P. 1 lb. 50 per cent per 100 gallons or 1I quarts of dieldrin
emulsion per 100 gallons or 11 per cent dieldrin dust have been effective for a more
delayed control. Heptachlor and aldrin are also effective materials for cutworm
- 2 -
Preventative measures for cutworms: It has been observed that very large popula-
tions of cutworms build up in weedy fields particularly on sticker weed (spiney
amaranth), probably the favorite host plant in the Everglades. Female moths seem
attracted to this plant for egg laying and each female may lay from 300 to 1800
eggs. If such areas are allowed to stand, an occasional insecticide application
would prevent this tremendous build up. Heavy populations are most likely to occur
between December and May. If these areas have not been treated and are disked after
several weeks thousands of hungry cutworms may migrate out to adjacent land in croj.,
Many will remain and attack crops planted in the new area. The destructive stage
during March, April and May feeds for about one month. During the colder months
this period is prolonged,
The alternatives are, (1) disk frequently enough to prevent the moths
laying many eggs, (2) allow weeds to grow but give an occasional insecticide appli-
cation, (3) do nothing until land is to be used and have a heavy population with
many worms of advanced stage that are harder to kill. Each grower must decide
which course is most economical for him.
Treatment of Growing Crops for Cutworms and Other Larvae: Treatments listed in
Table I offer the best control for cutworms, cabbage looper, imported cabbage wcr
diamond back moth, and other larvae attacldng cabbage and other crucifers, under
current residue tolerances. DDT is not included since this material has not given
satisfactory control of loopers and imported cabbage worms in recent years and the
materials listed have given satisfactory control of all the larvae commonly attack-
ing cabbage. A spray containing 2- lbs. of 40 per cent wettable toxaphene and 1 Ibe
of 15 per cent wettable parathion has given excellent control of all the worms,
aphids and leaf miners attacking cabbage and should give adequate control of Harle-
quim bugs, cucumber beetles, flea beetles and grasshoppers.
Unless frequent inspections can be made to determine if insects are pre-
sent in injurious numbers, weekly insecticide applications should be made to be
sure that a minimum of loss through insect injury is sustained.
There is no substitute for proper timing and thorough application.
Table I. Control for Cabbage Insects
Cabbage Loop- Toxaphene W.P. 1 lb. Technical Toxa- 100 gals. May be used to 21 days of harvest
er and other 40% phene (2 lIbs, 40%) per acre
Larvae per 100 gals.
Toxaphene 30 Ibs, May be used to 21 days of harvest.
10% dust per acre
Larvae, Toxaphene W.P. 1 lb. Technical (2k Ibs. 100 gals. Should give very good control of all insects
Leaf Miners, + Parathion 40%) Toxaphene + 0.15 per acre commonly attacking cabbage. May be used to
Aphids, etc. W.P, Ibs. Technical Parathion within 21 days of harvest,
per 100 gals. (1 lb. 15%)
Aphids, Parathion W.P. 0.15 Ibs. Technical 100 gals, May be used to 7 days of harvest
leaf miners, 15% Parathion per 100 gals, per acre
loopers (1 lb. 15% WP.)
and Other Parathion 30 lbs. May be used to 7 days of harvest,
Larvae 1% dust per acre Should give adequate control of all insects
commonly attacldng cabbage if good control
was obtained in earlier stages of development.
It is suggested that each grower obtain a copy of Florida Extension
Vegetable Pesticide Tolerances",
Circular 1h0, "Some Questions and Answers on