Slugwatch UK: 48% of sites at risk

Picture: Very high numbers of slugs are being caught this autumn in seed beds and wheat crops, particularly following Oilseed Rape.

The latest results from Slugwatch UK show high levels of slug activity in winter wheat crops across England. During the month ending 18th October, catches at 48% of sites exceeded the HGCA risk threshold of four per trap and only 12% of sites appeared to be free of slug activity.

Unseasonably high temperatures combined with ample moisture have given slugs ideal conditions this autumn. "Most of the 25 sites we've been monitoring have been at risk since drilling", Bayer's Dr Bill Lankford reports. "Even after ploughing we've recorded above threshold counts and some fields that were treated earlier with metaldehyde pellets are now needing follow-up applications."

The purpose of this surface monitoring work is to facilitate adoption of the HGCA's latest guidelines for integrated control. "Quantification with bait trapping is relatively straightforward, albeit time consuming. It's the interpretation of slug numbers in the light of site specific criteria that determine risk and that's what our field teams are working on with growers' agronomists."

As an example he cites a farm in Buckinghamshire where the highest count of 32 slugs per trap was recorded in October. "This was in a field of first wheat after oilseed rape, next door to a field of second wheat on the same farm with the same soil type, where we found just two slugs per trap. Clearly quite different strategies are required for these dramatically contrasting situations."

Given the high level of slug activity this autumn he urges growers to keep up their guard as winter approaches. "Where high numbers have already been recorded, crops are likely to remain at risk into November and follow-up pellet applications may well be justified. In such situations pellet choice is critical; only methiocarb-based pellets can be relied on for effective slug control under extremes of wet and cold."

Growers wanting more information on slug control can refer to the Bayer CropScience Expert Guide: Slugs available at www.bayercropscience.co.uk and HGCA topic sheet 84 Integrated slug control in winter wheat available at www.hgca.com