Keep checking your crops: Leatherjackets pose a risk until June

UK - May 16, 2006

Leatherjacket damage to arable crops, especially sugar beet, is showing up with increasing frequency across the eastern counties, and growers can expect damage to continue until June. 

Soil sampling earlier this year, by Dow AgroSciences, showed exceptionally high levels of leatherjackets across the UK with the highest levels after grass. 

Leatherjackets normally start pupating in June.  Feeding will stop and there is unlikely to be a worthwhile response to spraying.  But leatherjackets are at their most voracious just before pupation so there is a high risk of severe damage throughout May.   

Jim Butchart, Dow’s technical specialist says, “Damage can be rapid with crops being written off within a few days of germination.  We recommend an application of 1.0 kg/ha of Dursban WG (chlorpyrifos) as soon as treatment thresholds are reached.  Use high water volumes, up to 400 l/ha, to get the best possible results, particularly in dry conditions.”   

He advises growers and advisors to keep checking fields, especially high value crops such as vegetables and sugar beet after grass.  “We recommend growers do not incorporate Dursban WG when establishing a re-drilled crop and to spray after sowing,” says Mr Butchart. 

Andrew Watson of Norfolk-based Watson Agronomy, a council member of the Association of Independent Crop Consultants, believes this year’s leatherjacket problem is the worst he has ever seen. 

“One client had 20 acres of sugar beet totally written off within three days because of leatherjacket feeding.  It has now been re-drilled and sprayed post-drilling with Dursban WG (chlorpyrifos).  Another sugar beet field at the first true leaf stage has shown a 10% loss.  We’ve just sprayed it with Dursban, using 400 l/ha of water, because of the lack of rainfall,” says Mr Watson. 

He has also seen a bad attack of leatherjackets on late-drilled wheat.  All three affected crops were after grass.