In 2002 copper fungicides will be banned in countries of the European Union. In organic production copper is actually the only efficient fungicide to control late blight in potatoes. In a field screening we tested the efficacy of 26 different products, that could substitute copper. In field trials with micro-plots of 4m2 the two cultivars Bintje and Agria were infected artificially. We tested commercially available products used by organic growers, plant extracts, micro-organisms and resistance inducing compounds. The products were applied in weekly intervals and the disease development was examined every two to four days. With our screening we were able to detect products with an efficacy of 30 % or more. With the exception of Robus, a product based on natrium phosphite, only treatments with copper based fungicides surpassed this critical limit. Our results confirm the need of strongly enhanced activities to develop acceptable alternatives for copper in organic farming.
Zufferey V., Delabays N., Verdenal T., Reynard J.- S., Dienes A., Belcher S., Lorenzini F., Bieri S., Blackford M., Bourdin G., Spangenberg J.-E., Carlen C., Spring J.-L.
Reynard J.- S., Spring J.-L., Verdenal T., Zufferey V., Bourdin G., Bieri S., Carlen C., Crettenand F., Favre G.