Many crops, especially in southern England, could have escaped the threat from orange wheat blossom midge this season.

Forward wheat crops – especially those across much of southern England – should escape the threat from orange wheat blossom midge this season, say experts.

Recent cool and wet weather had kept midge activity to a minimum and, with many crops about 7-10 days ahead of usual, any increase in activity should miss the crop’s most susceptible period anyway, says ADAS entomologist Jon Oakley.

“Any crops flowering this week will probably be safe,” he told Farmers Weekly on Tuesday (29 May). “A lot have started to flower now, so it’s likely that much of the southern half of England could get away without needing to be sprayed.”

But where crops were less advanced – typically from Lincolnshire north – midge could still pose a threat if conditions turned warmer and more settled, he said. “It’s not over there yet.”

Lincolnshire AICC agronomist Ruth East agreed. “Early wheats have shot into ear and should escape, but later ones will be at risk.” Pheromone traps placed in fields before the rain last weekend found little activity, with only one registering numbers close to the treatment threshold, she said. “It looks like it’s going to be a very similar season to last year, when we only had to spray about 15% of crops.” If midge threat was particularly bad, she suggested applying chlorpyrifos.

If the weather turned warmer, she also advised growers to be wary of aphids, which would have increased after the wet weather. “Consider well-timed applications of Hallmark (lambda-cyhalothrin), or Biscaya (thiacloprid) where necessary. In some cases, we’ve had good result from just using pirimicarb,” she noted.

OWBM FACTS
  • Wheat most susceptible during ear emergence (GS 51-59)
  • Risk increased by warm weather and light winds
  • Check crops using traps and visual assessment
  • Use two pheromone traps per field and record catches every 2-3 days
  • Suggested control threshold is 20 midges per trap over 2-3 nights, or one midge per six ears in susceptible milling and seed varieties, or one midge per three ears for susceptible feed wheats
  • Prioritise treatment according to thresholds and crop value

Source: ADAS