Short-term field study on weeds reducing slug feeding on oilseed rape

The potential for three weed species to serve as alternative food sources a nd, thus, reduce feeding on oilseed rape by the field slug, Deroceras retic ulatum, was investigated over 4 weeks after rape emergence. Stellaria media Capsella bursa-pastoris and Taraxacum officinale were sown in high densiti es between rows of rape plants within slug-feeding arenas with 10 and 20 sl ugs m(-2), respectively. At low slug density, significantly more rape plant s survived in the S. media and C. bursa-pastoris treatments than in the unt reated control. The protective effect of S. media and C. bursa-pastoris did not differ significantly from that of metaldehyde pellets, the commonly us ed molluscicide. However, metaldehyde plots contained significantly more ra pe plants than T. officinale plots. In the plots with 20 D. reticulatum alm ost total crop failure occurred where weeds were sown. The efficiency of th e metaldehyde pellets Mras independent of slug density.