Watch bulb fly hatch

12 February 1999

Watch bulb fly hatch

WHEAT bulb fly egg hatch is well under way in the east and north.

And while the initial threat was lower than usual last autumn, growers must be on their guard and prepared to spray crops if necessary, advises ADAS entomologist John Young.

That is because there are more vulnerable late sown crops this season than usual, he explains.

"We are currently at the in-between stage with egg hatch increasing, but not quite at its peak," says Mr Young. "In the east and north it is about 20%."

Where chlorpyrifos egg hatch sprays have been delayed on backward crops, especially after roots on lighter land, he advises tank mixing with dimethoate. "But it is still cost-effective to use chlorpyrifos, for example Dursban."

Forward, well tillered crops are less of a worry. "You can wait to assess the risk and need for a dead heart dimethoate spray in two to three weeks time," Mr Young advises.

All comments assume that anti-bulb fly seed treatment has not been used, he notes.

lIt is probably too late to get a worthwhile response by tackling BYDV-bearing aphids in cereals, says Hants-based colleague Jon Oakley. Although autumn spraying was disrupted, he believes BYDV should be no worse than average, because more crops were sown later.

But Dorset-based Laurence Oades of Bayer, who found BYDV in a crop near Weymouth before Christmas, suggests it could still be worth adding an aphicide if fields are due for herbicide. "I have never seen BYDV so early." Many crops normally sprayed twice only had a single treatment last autumn, he says. &#42

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