Delayed drilling of some spring cereal crops as a result of wet soil conditions will result in later emerging seedlings being more susceptible to the effects of barley yellow dwarf virus (BYDV) infection, growers are being advised.
The threat to crops is compounded by high numbers of winged aphids on the move, according to Syngenta technical manager, Pete Saunders.
Aphids that are already carrying the virus, picked up from infected crops over the mild winter, can rapidly transmit BYDV - with younger plants more susceptible to infection and potential to suffer greater losses. After prolonged aphid activity through the autumn, the level of infection sources for transmission this spring is predicted to be high.
Mr Saunders says: “Seeking to keep initial infection of BYDV out of the crop is crucial to prevent hot-spots of disease, which could be rapidly spread by further aphid feeding activity.”
Results of aphid monitoring have already highlighted large numbers of aphids ready to migrate after the relatively mild winter - including the bird cherry aphid and grain aphid most closely associated with BYDV transmission. Adult grain aphids and young nymphs could be readily found on all wheat varieties at the Syngenta Innovation Centre in Oxford during March, adds Syngenta trialist, Tom Clarke.
While Storm Katie’s wet and windy weather may have checked movement over the Easter weekend, the sheer numbers of aphid present in crops and surrounding fields would be likely to trigger new flushes during every mild and settled period, he adds.
According to the latest aphid monitoring information from AHDB and Rothamsted Research, field reports suggest overwintering success of aphids within crops has been exceptional this winter, especially in southern and western England. There were no reports of BYDV in winter wheat as of April 1 but patches are said to be evident in winter barley, especially in the western England. The cut-off point for sprays against BYDV is thought to be GS31, after which no further economic benefit accrues.