BeneficialCorn earworm
Bt (kurstaki) for corn earworm
Bacillus thuringiensis kurstaki · microbial insecticide
Against corn earworm
Bt only works if a larva eats it before burrowing in. In corn the larvae reach the ear tip within a day of hatching, and in tomato they enter the fruit quickly, so coverage has to be in place at egg hatch. The home Thuricide label claims only suppression of tomato fruitworm. UC IPM notes that Bt does not destroy the natural enemies of tomato pests.
RateLabel rate — DiPel DF lists corn earworm/tomato fruitworm; Thuricide 2–4 tsp per gallon on tomato claims suppression only
TimingSilks and fruit from first egg hatch, before larvae enter; repeat through silking
macro · bt (kurstaki) on corn earworm
The pestCorn earwormHelicoverpa zeaEar tips eaten and full of frass; holes in tomato fruitFull pest profile →Before you order
A bacterium sprayed on leaves. Caterpillars that eat it stop feeding and die within a few days. It works only on the larvae of moths and butterflies, and has little or no effect on bees, lady beetles, lacewings or parasitic wasps. How it works, how to tell it has established and the supplier list are on the full Bacillus thuringiensis kurstaki profile.
Other controls for corn earworm
- Trichogramma spp.Egg parasitoid wasp · About 100,000 T. pretiosum per acre during egg-laying (UC IPM, tomato); 1–2 /ft² in gardens (Sound Horticulture)
- Orius insidiosusPredatory bug · 1–2 /m² per release; up to 10 /m² on hot spots
- Braconid waspsWild parasitoid · wild, attract it
- Damsel bugsWild predator · Wild — not sold; conserve the ones already present