Bluegreen aphids

Agronomist, Adrian Tyler (Tyler’s Hardware & Rural Supplies), has reported finding aphids in several lentil crops around Rupanyup, in the Wimmera district of Victoria. They have been identified as predominantly bluegreen aphids (Acyrthosiphon kondoi), however a small number of cowpea aphids are also present. High numbers have been collected when sampling with a sweep-net. Adrian says he has commonly been finding several hundred aphids in lots of ten sweeps in many lentil crops. Agronomist, Paul Parker (NSW DPI), has reported aphids in very high numbers in several lucerne paddocks around Young, in the South West Slopes district of New South Wales. Although the species responsible is still to be confirmed, there is obvious feeding damage apparent across many paddocks.

Bluegreen aphids are a large species, measuring up to 3 mm long as adults. Both the winged and wingless forms are a matt bluish-green in colour. Annual medics, lucerne, subterranean clover and lupins are susceptible to bluegreen aphid. In lucerne and medics, heavy infestations cause stunted growth, leaf curling and leaf drop. In subterranean clover, leaves wilt before turning brown and dying. Bluegreen aphids favour growing tips of medic and lucerne, while in clover they are widely dispersed under the canopy.  Click here for images of bluegreen aphids.

Aphids have also been found in some bean crops, however these have generally been in lower numbers than seen in lentils. This year has been particularly bad for aphids in many parts of the Wimmera. Adrian says chemical control may be necessary to prevent yield loss. Where possible, chemical applications will be timed to achieve control of both aphids and native budworm simultaneously.

Paul recommends looking at the paddock history of crops badly infested with aphids. The worst affected paddocks may be those with a strong cropping history (e.g. several years sown to lucerne), which may be contributing to crops being stressed this season. Aphids often target plants suffering from moisture stress and/or nutrient deficiency.