Diamondback Moth Control

Symptoms

Small greenish caterpillars scrape the underside of leaves leaving the upper skin intact, which dries into small white windows or papery patches. As they grow they make irregular holes and a shot hole appearance in the leaves. In cabbage and cauliflower they bore into the heart and curd, contaminating it with larvae and excreta.

Damage

Diamondback moth is the most destructive pest of cole crops worldwide and in India and can cause losses of 50 to 80 percent in unprotected cabbage and cauliflower. It has developed resistance to many insecticides, making it hard to control by chemicals alone. Damage to the head and curd lowers both yield and market quality.

Organic & cultural control

Spray Bacillus thuringiensis which is highly effective against young diamondback larvae and safe for natural enemies. Use pheromone traps at 5 to 10 per acre for monitoring and mass trapping of males. Grow a few rows of mustard as a trap crop to attract and concentrate the moth. Release the parasitoid Cotesia plutellae, conserve other natural enemies, and spray neem seed kernel extract.

Chemical control

Because the moth resists many insecticides, use newer recommended molecules such as spinosad, emamectin benzoate, chlorantraniliprole or flubendiamide and strictly rotate between different groups so resistance does not build up. Direct the spray to the underside of leaves and add a wetting agent on waxy cole leaves. Use only labelled products at the correct dose, follow the pre-harvest interval and consult your KVK or agronomist before spraying.

Always follow the product label, the recommended pre-harvest interval, and your local KVK or agronomist. Pesticide approvals change, so verify before use.

Prevention

Use healthy seedlings and avoid staggered overlapping cole crops which keep the moth going year round. Grow a mustard trap crop around the field, set up pheromone traps from the start, and rely first on Bacillus thuringiensis and natural enemies before chemicals. Remove crop residues after harvest and rotate with non cruciferous crops.