A system approach to biocontrol in organic and integrated strawberry production

The use of high plastic tunnels in strawberry production solves a majority of the problems with plant pathogenic fungi, with a major exception of powdery mildew. However, tunnels tend to increase the problems with spider mites and certain other pests. The interactions between pest insect and mites, plant pathogenic fungi and natural enemies are numerous and complex, and therefore often studied separately. To understand how we can manage a complex plant protection problem in a specific crop, a system appro ach is needed. Some studies have already been conducted on the effect of tunnels and pesticides on spider mites and predatory mites, and some of them have included the interaction with certain plant pathogenic fungi. None of them have, however, included a n important natural enemy, the mite pathogenic fungus Neozygites floridana, and we believe that this may have resulted in mistaken conclusions and hence wrong recommendations for growers. The goal of this project is therefore to enhance organic and sust ainable production of strawberry and reduce the use of pesticides and problems with pests and plant pathogenic fungi in tunnels and open field through a system approach. We will use the two-spotted spider mite, its natural enemies (N. floridana and predat ory mites) and powdery mildew as a model system. Experts from the different fields of acarology, mite- and plant- pathology and production systems are all partners in this project. The experimental approach in the project will be based on conservation, in oculation and inundation biological control. In collaboration with Koppert Biological Systems, we also aim to develop inoculation and large-scale production methods for N. floridana. The project will provide knowledge resulting in information and guidelin es for how to manage cropping systems in strawberry in a manner that reduces problems with spider mites and fungal diseases and conserves and enhances predatory mites and the beneficial fungus N. floridana.