Cold should curtail fly egg hatch, says ADAS

10 January 1997

Cold should curtail fly egg hatch, says ADAS

WHEAT bulb fly egg hatch is likely to have been delayed by the cold spell. Growers should hold off treatment until the results of the first ADAS field sampling results are known.

"We have no hard information yet. We started sampling on Monday, so we will know next week whether the hatch has started," says John Young, ADAS entomologist at Boxworth, Cambs.

He thinks that is unlikely. Egg hatch stops when soil temperatures drop below 3C, and soils have been frozen in most of the eastern side of the country since before Christmas.

A slow start is more likely. "In the last three years, hatch started in early January, with the main phase in early February. What happens this year depends on how long the cold spell lasts. If it stays, we may not see the main hatch for a few weeks."

Applying sprays too soon could risk inadequate protection later on, he warns. A protracted hatch could mean protection is needed for up to three months. "Wait until the hatch before spraying."

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