The Use of Copper Pesticides in Germany and the Search for Minimization and Replacement Strategies

Copper pesticides used to control fungal and bacterial diseases such as grapes downy mildew (Plasmopara viticola), downy mildew of hops (Pseudoperonospora humili), apple scab (Venturia spp.), fireblight (Erwinia amylovora) and potato late blight (Phytophthora infestans), play an important role in plant protection. In a 2013 survey of copper application in Germany we found, that while the amounts of copper used per hectare in conventional grape (0.8 kg ha−1), hop (1.7 kg ha−1) and potato-farming (0.8 kg ha−1) were well below those used in organic farming (2.3, 2.6 and 1.4 kg ha−1, respectively), they were nearly identical to those used in apple growing (1.4 kg ha−1). Due to the smaller farming area, only 24% (26.5 tonnes) of the total amount of copper was applied in organic farming compared to 76% (84.8 tonnes) in conventional farming. Since 2001, the Federal Agency for Agriculture and Food (BLE) promoted a copper research and minimization strategy which was funded with a total of C10.2 million. Our status quo analysis of research in this field shows that some progress is being made concerning alternative compounds, resistant varieties and decision support systems. However, it also shows that new approaches are not yet able to replace copper pesticides completely, especially in organic farming. In integrated pest management, copper preparations are important for the necessary active substance rotation and successful resistance management. The availability of such products is often essential for organic grapes, hops and fruit production and for extending the organic farming of these crops. We conclude that the complete elimination of copper pesticides is not yet practicable in organic farming as the production of several organic crops would become unprofitable and may lead to organic farmers reverting to conventional production. Several existing copper reduction strategies were, however, identified, and some, like modified forecast models adapted to organic farming, varieties more resistant to fungal diseases and new alternative products, already contribute to copper minimization in German agriculture.