A 'LOW risk' assessment for the threat from the wheat bulb fly pest, does not apply to Scotland, the SRUC has warned.

While English growers have been advised they can rest easy, the risk to Scottish wheat crops, especially those in the south and east, is very real, according to Dr Andy Evans, a pest management expert with SRUC’s Crop and Soils Research team.

“Results from our wheat bulb fly egg survey indicate an increased risk this season. Approximately 50% of the fields monitored so far exceed the damage risk threshold of one million eggs per hectare - in crops sown after mid October. The highest egg count, of nearly 6m eggs per ha, was recorded in East Lothian,” he said.

The fly and its larvae are serious pests in the eastern half of Scotland. They lay their eggs in bare soil from July into September, hatch in January or February and as the larvae feed on the growing plants cause the so-called 'dead heart' symptoms which can completely kill plants.

“Around 20% of fields tested exceed the 2.5m eggs per ha threshold for wheat sown before mid-October," added Dr Evans. “However, there is a particular risk for wheat crops sown after mid-October, where half of the fields we tested had egg counts over the 1m eggs/ha damage threshold.”

SRUC is recommending that growers identify fields at risk now and be prepared to get them sampled as soon as possible. This can be done by staff from their local SAC Consulting offices.

With increasing restrictions on the range of pesticides available for control, Dr Evans suggested farmers take a balanced, informed view of the situation and consider the options.

If egg counts are below damaging levels, do nothing. If counts are potentially damaging, use seed treated with the pesticides Austral Plus or Signal 300 CS, particularly for later-sown crops of wheat.

“The loss of chlorpyrifos as an egg hatch treatment makes the seed treatments the only chemical management for this pest,” added Dr Evans.