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Imprint
Application of naturally occurring antagonists of the cabbage white fly (Aleyrodes pro-letella) in organic brassica crops in combination with netting
Project
Project code: 2806OE339
Contract period: 01.04.2007
- 30.04.2010
Budget: 204,742 Euro
Purpose of research: Applied research
The cabbage whitefly, Aleyrodes proletella has developed to a key pest in brassica vegetables throughout Germany In a 3-year project we investigated the barrier effect of netting (0.8 x 0.8mm) in combination with the native parasitoid Encarsia tricolor and the predator Clitostethus arcuatus in an inundative approach in Brussels sprouts. Netting alone reduced whitefly larval densities by 77% at peak infestation in all years. Mechanical weeding forms a critical time slot for first infections by A. proletella under netting. Forgoing mechanical weed control by employing biodegradable mulch materials did not result in lower pest levels.
Whitefly antagonists were reared by the Katz Biotech AG. Results of accompanying quality controls and of biological characterisation of the used E. tricolor strain were directly applied for adjustments of rearing conditions. In a field plot experiment, parasitism significantly increased after E. tricolor releases inside nets compared to netted controls without release. Preponing the timing of the first release about 3 weeks to early July in 2009 resulted additionally in a significant reduction in pest density by 39% and a 23% increase of marketable yield. By contrast, C. arcuatus did not prove to be an efficient biological control agent in the open field. An additional on-farm trial confirmed the control potential of E. tricolor. Concentrated releases of E. tricolor in the open field increased parasitism by 50% in 2008/2009. Furthermore, a 60% reduction of A. proletella density was achieved by moving forward the release date by three weeks in 2009. The project provides an indispensable basis for successful applications of E. tricolor by proving field establishment of the parasitoid as well as first control and yield effects of releases. Further research has to focus on the adjustment of release rate, timing and frequency to optimise control.
Section overview
Subjects
- Crop Protection
- Vegetable Gardening
- Organic Farming
Framework programme
Federal Organic Farming Scheme and other forms of sustainable agriculture (BÖLN)
