Leatherjackets pose a seedling risk in new leys

16 July 1999

Leatherjackets pose a seedling risk in new leys

BEWARE of leatherjackets threatening emerging seedlings when establishing new grass leys this year.

Leatherjacket numbers were high last year and because of damp conditions it is likely they will be a threat again this year, says IGER North Wykes Bob Clements.

"It is a sporadic and patchy problem countrywide, but will be particularly concentrated in the west. New swards suffer due to carryover of leatherjackets from old to new pastures."

Leatherjackets, the larvae of common crane flies, are more of a problem in established grass, he says. While they can survive ploughing to damage new swards, they are more of a threat when direct drilling.

In severe cases of attack, when swards have been rotavated, numbers can reach 100,000/ha (40,000/acre), says Dr Clements.

Producers are advised to take a sample and use a risk assessment kit, available from Dow AgroSciences. "This kit gives you a good guide as to whether you should spray."

Other ways of reducing risks of damage is to use an arable break crop. "In a grass area this may not be easy, but a switch to maize or whole-crop cereal for a year will solve the problem," he adds. &#42

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