Aphid threat to potato crops

Scottish seed potato growers, who are only now drawing breath after one of the latest planting seasons, have been advised to look out for virus-transmitting cereal aphids as soon as the crop emerges through the ground.

In Scotland, cereal aphids overwinter as eggs so winter temperatures have minimal impact on their survival or first flight. In a normal season, rose-grain aphids generally start flying in April to early May followed by grain aphids in late May to early June; both building to peaks in late July.

However, Eric Anderson of Scottish Agronomy’s view is that crops are about three weeks behind schedule. As such winter cereal crops will still be green and attractive to cereal aphids as soon as they appear. The cereals will provide the food source needed for aphid numbers to build by the time seed potato crops emerge, which he estimates will be mid-June at the earliest.

This means Scottish seed growers should be thinking ahead about how best to control cereal aphids. He advocates a spray programme.

Anderson also highlighted a new aid to help in decision making. Work by SASA’s w Jon Pickup has developed “varietal propensity” to indicate whether symptoms observed in a variety at crop inspection have been above or below the average across the whole Scottish seed crop for the last four years.

Growers can assess whether a variety is more or less at risk to a virus. Use of the information will allow growers some flexibility in the timing of commencement of their virus management programme.