Forecast rain for this week should ease any potential damage from higher than usual numbers of black aphids being found in sugar beet crops, according to Mike May of Broom’s Barn.

The Research Station had received more reports than normal from growers finding the pest, he said. “Usually colonies build up on odd plants, but this season there appears to be smaller colonies, which suggests they are still coming in, on a greater numbers of beet, possibly as a result of spread by the recent winds.”

Healthy plants should be able to withstand black aphid feeding
without yield penalty, says Mike May of Broom’s Barn

Feeding damage was the main issue black aphids could cause. While plants remained turgid (healthy) damage was minimal but if crops wilted the aphids could cause an extra 10% yield loss on top of the effects from drought, Mr May said.

The aphids also tended to move to new plants when plants wilted, which, if the beet plant was already carrying beet yellows virus, could spread the disease, he noted.

“Fortunately it is raining here now, and I think we should be OK.” If it did stay dry and there was a need to spray, growers should use pirimicarb (Aphox) so the growing numbers of ladybird larvae were not affected.