Mustard Aphid Control

Symptoms

Small soft greenish to grey aphids cluster in large numbers on tender shoots, leaves, flower stalks and developing pods, sucking the sap. Affected plants show curled and yellowing leaves, stunted growth, twisted shoots and poor pod and seed set. A sticky sugary coating called honeydew develops on which black sooty mould grows, blackening the plant.

Damage

Mustard aphid is the most damaging pest of rapeseed and mustard in India and can cause yield losses from 10 to over 60 percent, and in severe early attacks even higher. It also lowers oil content and seed quality. Cool, cloudy and humid weather in December and January favours rapid build up to damaging numbers.

Organic & cultural control

Install yellow sticky traps at 10 to 12 per acre to catch winged aphids and monitor build up. Spray neem seed kernel extract 5 percent or neem oil at first sign of colonies. Conserve and release natural enemies like ladybird beetles, syrphid flies and Chrysoperla which feed heavily on aphids. Spray Beauveria bassiana or Verticillium lecanii in humid weather. Remove and destroy heavily infested terminal shoots early.

Chemical control

Spray when aphids cross the threshold of about 20 to 25 aphids per plant or per 10 cm of central twig on 10 percent plants. Recommended actives include dimethoate 30 EC, imidacloprid 17.8 SL or thiamethoxam 25 WG. Spray in the evening to protect pollinators since mustard flowers attract bees, and avoid spraying during peak bee activity. Always follow the product label for dose and pre-harvest interval and consult your KVK or an agronomist before use.

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

Prevention

Sow early in the recommended window so the crop crosses the sensitive stage before the aphid peak in late December. Use recommended seed rate and spacing and avoid excess nitrogen. Grow tolerant varieties where available. Scout the crop weekly from the rosette stage and start control at the threshold. Keep yellow sticky traps up for early warning.