Tomato Fruit Borer (Helicoverpa) Control

Symptoms

Round bore holes appear on green and ripening fruits, often with the caterpillar pushing only its head inside while the rest of the body hangs out. Inside, the larva feeds on the pulp and seeds, leaving the fruit hollow, rotting and full of excreta. Early on the larvae also feed on tender leaves, flowers and growing shoots. The caterpillars are smooth, green to brown with light and dark wavy stripes along the body.

Damage

The fruit borer Helicoverpa armigera is the single most damaging pest of tomato and chilli and can cause fruit losses of 20 to 70 percent. One larva moves from fruit to fruit, damaging several fruits during its life, and the bore holes invite rot organisms that spoil the produce further. The same pest attacks chickpea, cotton and pigeonpea, so it is present almost year round and can build up quickly if not monitored.

Organic & cultural control

Install pheromone traps at 5 per acre to monitor moth activity and time your action. Set up bird perches so birds pick off caterpillars. Hand pick and destroy grown larvae and bored fruits in the early stages. Release the egg parasitoid Trichogramma chilonis and spray Helicoverpa NPV virus at 250 LE per hectare or Bacillus thuringiensis. Neem seed kernel extract at 5 percent or neem oil sprays deter egg laying and check young larvae. Grow a few rows of marigold as a trap crop to attract the moths.

Chemical control

When larval damage crosses the threshold, spray effective insecticides such as emamectin benzoate 5 SG, spinosad 45 SC, indoxacarb 14.5 SC, chlorantraniliprole 18.5 SC or flubendiamide, directing the spray at flowers and fruits where larvae feed. Spray in the evening when larvae are active and rotate between different insecticide groups every two sprays to delay resistance, since this pest develops resistance fast. Always follow the product label dose, strictly observe the pre harvest interval as fruits are eaten fresh, 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

Deep summer ploughing exposes pupae in the soil to the sun and birds. Avoid continuous cropping with other host crops like chickpea, cotton and pigeonpea nearby. Set pheromone traps early to catch the first moths, and grow marigold border rows as a trap crop. Use balanced fertiliser and avoid excess nitrogen that encourages lush growth attractive to the pest. Monitor regularly from flowering and act when you find a few eggs or young larvae rather than waiting for heavy damage.