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Cowpea aphids

The early April warnings of cowpea aphid have eventuated into serious pest threats in some regions of NSW and Victoria.


Where have they been reported?

Cowpea aphids (Aphis craccivora) have been reported in very high numbers (>50 per plant) on a number of faba bean crops around Breeza, in the NSW North Western Slopes & Plains district. In some crops, almost 100% of plants were found with aphids. There is some concern that these aphids may transmit the subclover stunt virus, or go on to invade nearby chickpea crops. In the Victorian Mallee, crops of faba beans, lupins and vetch stretching from Murrayville over the Victorian border to Lamaroo have been heavily infested with cowpea aphids. Further details on the cowpea aphid can be found in PestFacts Issue No. 1.

Our advice

Growers should remain alert to the risk of aphids causing damage and spreading virus in legume crops, particularly grain legumes, this season. Expected losses from direct feeding of aphids on faba beans are unknown. The opportunity to avert the initial transmission of virus to crops has passed, assuming the invading aphids were viruliferous in the first place. The risk of further spread of viruses within crops depends upon the initial risk of virus in local, intermediary hosts. NSW DPI Plant Pathologist, Joop Vanlour, believes that the first symptoms of virus should appear by about the 10th of June.

Aphid populations are likely to decline with the recent onset of cooler temperatures, especially after frosts. There are no specific chemical recommendations in place for aphid control in faba beans. 'Softer' insecticides, particularly pirimicarb, are the preferred option as they provide excellent knockdown of aphids but are relatively harmless to beneficial insects. It is the beneficials that often contain subsequent aphid populations.


* Sources of field reports of cowpea aphids

Peter Gibbs, Agronomist, Gibbs Agricultural Consulting (Victorian Mallee)

Joop Vanlour, Plant Pathologist, NSW DPI (NSW North Western Slopes & Plains)

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