ICM approach helps bulb fly management

18 July 1997

ICM approach helps bulb fly management

LEAF-STYLE integrated crop management is helping wheat bulb fly management at Woodbastwick Estate, according to independent agronomist John Purslow.

Egg hatch was high this season, tempting a spray treatment. But a field assessment in Brigadier wheat suggested there were more than enough potential ears to survive attack and still produce a good crop. "So we left it," says Mr Purslow.

"We had 250-300 plants a sq m with four tillers each. That is a potential of 1000 ears a sq m. But this land wont sustain high ear numbers."

In the event 60 plants a sq m were attacked by bulb fly and another 20 by opomyza, he says. The remaining untreated stand looks full of promise with about 800 ears a sq m.

Mr Purslow admits the same approach may not apply to heavier land with higher yield potential. But by not spraying, the farm has saved about £17.50/ha for a pre-egg hatch spray and another £5.60/ ha for a dead-heart treatment. The latter, usually dimethoate, are questionable anyway, he says. "They are often only done in revenge and they kill predatory insects."

The plan now is to raise seed rates by 20/sq m to allow for potential bulb fly damage. At an extra cost of only £3.30/ha it compares well with the expense of spraying, he says. "And it maintains healthy beetle populations." &#42

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