Grain aphid could be a greater threat this autumn
This autumn may see a greater and more challenging aphid migration into cereal crops because of the growing instances of pyrethroid resistance in the grain aphid, raising fears over barley yellow dwarf virus control this autumn.
HGCA-supported testing at Rothamsted Research has discovered that aphids carrying the kdr mutation – associated with resistance to pyrethroids – have increased in frequency this year. The mutation was first identified in the UK last year, mostly in East Anglia, said Caroline Nicholls, HGCA research and knowledge transfer manager.
In addition to samples from UK suction traps, samples from 27 wheat farms across England and further resistance testing based on live aphid bioassays, co-ordinated by IRAG, have also shown increased levels of the mutation.
Although much of the season has not been particularly conducive to grain aphid epidemics, wet weather has created a “green bridge” (grassweeds and volunteers) that may persist in cereal stubbles and act as a source of both aphids and virus if not adequately destroyed prior to drilling a succeeding cereal crop, she said.
Aphids may migrate into newly emerging cereal crops in larger numbers than usual this autumn, if the weather is conducive to successful flight, particularly with warm temperatures (more than 15C).
“Although the bird cherry-oat aphid (Rhopalosiphum padi) is usually considered to be the more important vector of BYDV, the grain aphid is also an important vector. Therefore, it is crucial to understand how best to manage grain aphids,” said Miss Nicholls.
For more information, see the HGCA’s new information sheets on aphid management, including best practice measures to limit the risk of resistance and strategies that could be deployed if resistance is suspected during the autumn spraying period.
