Strohmulch gegen Blattläuse im Gemüsebau

Summary

One way to prevent the colonisation of crops by insect pests is to disrupt their host finding behaviour. As immigrating aphids alight on potential host plants using optical stimuli, this process can be manipulated by altering the contrast between plant and background. This study aims to test the aphid repelling properties of straw mulch in vegetables. We applied straw to broccoli, head lettuce, bush bean, vegetable broad bean and carrot. The trials were conducted in 2002 and 2003 at several locations in the area of Brunswick, North Germany. Numbers of aphids were insignificant in carrots but noticeably reduced in mulched broccoli, bush bean and broad bean (Brevicoryne brassicae and Aphis fabae respectively). However, this result was significant only in one of two growing locations. We could not observe any reduction of aphid numbers in mulched lettuce. This finding might relate to lettuce leaf colour. Natural antagonists of aphids as well as other vegetable pests such as lepidoptera and root flies were not affected by straw mulch. The influence of soil type, number of immigrating aphids and cropping environment on the effectiveness of straw mulch warrants further research.