Potato growers need to look out for signs of wireworm activity as the weather becomes milder, experts have advised.

While there has been little activity during the recent cold spell, as soils start to warm up wireworm will be attracted to bait traps and it should be possible to detect their presence, said United Agri Products’ Barrie Florendine.

He believes the pest is becoming an increasing problem in arable rotations and is occurring more frequently in eastern counties and is not just restricted to the west and north.

“[Last season] we saw sudden and unexpected patches of damage in otherwise grass-free rotations, which in some situations was quite significant, with loads being rejected or needing to be re-graded.”

A minimum of five bait traps per hectare should be used, as populations of as low as 60,000 per hectare can cause major economic damage, he said.

If wireworm are detected, growers may be able to switch planting to another field, or choose an earlier harvested variety, but in many cases this will not be practical and treatment with a soil insecticide may be needed, he said.

Mr Florendine favours Mocap (ethoprophos) at 60kg/ha to provide the required concentration of treatment throughout the ridge.

Nemathorin (fosthiazate) in-furrow, he says, gives a greater concentration around the seed tubers, but tends to “run out of steam” when the main damage to daughter tubers occurs during late July and August.