Entwicklung und Regulierung eines Schaderregerkomplexes an Himbeerruten

The increasing damages on fruiting canes in raspberry plantations are caused by the disease complex ‘midge blight’, in which different fungi and the raspberry cane midge are involved. The larvae of the midges feed in the first year in primocanes and damage the periderm, so that fungal pathogens are able to penetrate into the internal cane tissues and can cause vascular lesions. Death, but failure or lateral wilt results in the second year from damages of the xylem. In a two-year-old survey the growth of canes and the development of the fungal complex and the raspberry cane midge was investigated in different plantations. The most important factors of the disease complex could be related to each other. Subsequently the influence of growth management of young canes and chemical control of the midges on the health of the canes were investigated. The delay of the emergence of the primocanes in spring reduced the occurrence of natural splits and the xylem lesions. The post-harvest applications of insecticides against the third generation of the cane midge had a similar effect, whereas the effect increased along with the delayed emergence of primocanes. This can be related to the fact that the growth management of young canes is shifting the disease complex and its main damage period so that the efficacy of chemical control measures against larvae in august will increase. The results are the base for the future development of a control strategy.