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Diamondback moths larvae attack only plants in
the family Cruciferae. Virtually all cruciferous vegetable crops are
eaten, including broccoli, Brussels sprouts, cabbage, Chinese
cabbage, cauliflower, collard, kale, kohlrabi, mustard, radish,
turnip, and watercress.
Biological control: There are several biological
enemies that help control diamondback moths. For example, in
Honduras, the parasitoid wasp Diadegma insularis
(Hymenoptera: Chalcididae) can kill up to 40% of the
caterpillars when there is a limited use of synthetic pesticides. In
Asia, the parasitoid Diadegma semiclauson has been used on a
commercial basis for control of DBM caterpillars.
Chemical control: DBM has developed resistance to
the bacterial pesticide, Bacillus thuringiensis, var.
krustaki in areas where it is in heavy use, leaving farmers without
a useful pesticide. Because of severe pesticide resistance problems
with DBM around the globe, it is very important to use pesticides as
little as possible in an IPM program. You need to contact the local
authorities for the specific pesticides to use in your country. It
is recommended to make a pesticide screening study to find the best
pesticides to use in rotation between the different pesticide
families.
Cabbage plants contain large amounts of wax in the surface of the
leaves. This wax makes it very difficult for pesticides to stay on
the leaf surface. It is recommended to use spreader stickers to
increase pesticide coverage and persistency. The majority of DBM
caterpillars live under the leaf surface. For this reason, it is
very important to have an excellent pesticide coverage under the
leaves. Hydraulic nozzles are the best to use with backpack or
tractor sprayers. The use of electrostatic sprayers improves
pesticide coverage and reduces pesticide use.
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