Aphids increase as predators lag behind
RECENT trap results suggest aphid numbers are building and could pose a serious risk to autumn sowings – despite the relatively cold winter which meant few were seen in arable crops during early summer.
The numbers of aphids flying in recent weeks are at similar levels to this time last year. The Broom’s Barn aphid traps also record the number of ladybirds and these have not built up; at the moment they are at 25% of the level in 2009.
This could mean that the risk of turnip yellows (TuYV) in rape and BYDV in cereals this autumn might be higher than last year, said Adrian Cottey, seed treatment manager for Bayer CropScience.
“This is particularly worrying as our and other surveys for TuYV in the current crop show that levels are high in many areas. Growers will need to use a good seed treatment to control TuYV and BYDV.
“Clothianidin is a new generation neonicotinoid treatment that gives good control of establishment pests but, importantly, it also prevents aphids spreading these viruses.
“As Modesto in oilseed rape it is the only treatment with label approval for TuYV. As Redigo Deter it will control BYDV in cereals.”
Recent work by Broom’s Barn found TuYV present in all plant parts, including the roots of infected rape. Aphids feeding on regrowth in stubbles could therefore pick up the virus and pass on to newly emerged autumn crops.
“Volunteers can be reduced by good stubble cultivations, but the risk of virus transfer from other sources including weeds and field margins, suggest that investment in clothianidin seed treatments will be well worthwhile.
