Growers are being warned that there is an increased threat to grass leys, following a bumper year for the leatherjacket pest in 2013.
“Leatherjacket grubs are larger than usual for the time of year, so farmers need to be alert for any damage; particularly on establishing grass leys where they are following grass, but also to late drilled and spring cereal crops,” comments Brent Gibbon of Dow AgroSciences. “Hatched leatherjackets are vulnerable to desiccation, particularly when young, however the wet winter will have kept the soil moist and aided their survival.”
The stewardship initiative is urging growers to monitor fields known to have a history of leatherjacket damage, “Look out for large numbers of rooks and jackdaws feeding on the larvae,” notes Brent. “Cereals following established grass leys, a grassy stubble or spring barley are high risk crops. Permanent grassland and newly sown leys are also more likely to suffer yield damages from this pest, so growers need to be aware,” warns Brent.
“Chlorpyrifos is an effective insecticide, which following months of feeding by the pest can help prevent further damage, thus protecting the yield. It is vital that farmers firstly, have a strong knowledge of their land’s pest and disease history, and secondly look for indicators of leatherjackets in their crops, before treating.
“In recently planted crops, checking the top soil gives a good idea of pest activity; using a trowel, lift a few clods of soil working across the fields, a couple of inches deep to see if there are any grubs. Once the crops start germinating look for signs of damage around the base of the plant and the root. Be sure to treat at the first sign of activity,” advises Brent.
When applying chlorpyrifos for treatment of leatherjackets, growers should use LERAP rated 3 star nozzles and adopt a 20 metre no-spray buffer zone near to watercourses or a 1 metre near to dry ditches. “It is vital that growers adopt the stewardship guidelines when applying chlorpyrifos in order to help secure a future for this key insecticide,” concludes James.