Late sown spring cereals could be vulnerable to BYDV, so growers are advised to consider using a pyrethroid spray if aphids are easily found, according to ADAS.
BYDV is carried by the grain aphid and bird cherry aphid. AHDB reported first arrivals of these at some of its suction trap sites in the period April 30 to May 6. ADAS entomologist Steve Ellis says: “It has been relatively warm since then so I would have thought, if anything, the numbers would go up.”
Previous research comparing BYDV infection in plots sown on March 4 or 8 and April 13 or 24 found higher levels of BYDV in the later sown cereals, says Dr Ellis. “So anything that has just gone in is late sown and potentially at greater risk.
“If you can find aphids easily, it probably justifies a spray,” he adds.
However, resistance to pyrethroid insecticides has been detected in grain aphid so it is important to use the full rate, advises Dr Ellis. “It has not yet been detected in bird cherry-oat aphids and you should still get control of grain aphids with pyrethroid provided it is applied at the full rate.”
Once cereals are past GS31 they are no longer susceptible to damage, say Dr Ellis.