Mustard plants covered with green aphids on shoots and pods at flowering.
6 Answers
Mustard aphid is the most damaging pest of sarson and attacks from flowering to pod stage, sucking sap and stunting growth. The most important defence is timely early sowing so the crop flowers before peak aphid season. Monitor from flowering, and when colonies appear on the central shoots or about 10 percent plants are infested, take action. Spray neem based products early; at higher infestation use a recommended insecticide such as imidacloprid, thiamethoxam or oxydemeton methyl, and clip and destroy heavily infested terminal shoots. Spray in the late afternoon to protect pollinators, and avoid spraying during peak bee activity at flowering. Follow label doses and waiting periods, and confirm the current recommendation with your KVK.
Early sowing made the biggest difference for me in Aligarh. When I sow on time the crop is almost done flowering before the aphids peak, so I need very few sprays.
Clipping and destroying the worst infested top shoots before I spray helped a lot. The aphids cluster on the curled tips, and removing those carried away thousands of them, so my one spray then worked much better than spraying over a heavy infestation.
Please spray in the late afternoon when bees are not active. Mustard flowering brings in honeybees and they help the crop set siliquae. The year a neighbour sprayed mid morning many bees died and it is bad for everyone's yield. Late evening spraying protected the bees on my field.
Yellow sticky traps and a few weekly checks of the central shoots told me when the aphids were starting, so I did not spray blindly. Acting at the first colonies with neem held them, and I only used a chemical once when they crossed the threshold. Scouting saved me money on sprays.
Do not keep using the same insecticide every spray. Rotating between recommended groups kept them effective for me, whereas a friend who sprayed the same one repeatedly found it stopped working as well. Follow the label dose and the waiting period before harvest, and check the current advisory with your KVK.