Further Limitations of Synthetic Fungicide Use and Expansion of Organic Agriculture in Europe Will Increase the Environmental and Health Risks of Chemical Crop Protection Caused by Copper‐Containing Fungicides

Abstract

Copper containing fungicides are used in agriculture since 1885. The divalent copper ion is a non‐biodegradable multi‐site inhibitor, which has a strictly protective, non‐systemic effect on plants. Copper‐containing plant protection products currently approved in Germany contain copper oxychloride, copper hydroxide and tribasic copper sulphate. Copper is primarily used to control oomycete pathogens in grapevine, hop, potato and fungal diseases in fruit production. In the environment, copper is highly persistent and toxic to non‐target organisms. The latter applies for terrestric and aquatic organisms such as earthworms, insects, birds, fish, Daphnia and algae. Hence, copper fungicides are currently classified in the EU as candidates for substitution (CFS). Pertinently, copper also exhibits significant mammalian toxicity (LD50, oral = 300 – 2,500 mg/kg bw in rats). Until today, organic production still profoundly relies on the use of copper fungicides. Attempts to reduce doses of copper applications and the search for copper substitutes have not been successful. Copper compounds compared to modern synthetic fungicides with similar areas of use display significantly higher risks for honey bees (3‐ to 20‐fold), beneficial insects (6‐ to 2,000‐fold), birds (2‐ to 13‐fold) and mammals (up to 17‐fold). These data contradict current views that crop protection in organic farming is associated with lower environmental or health risks. Further limitations in the range and use of modern single‐site fungicides may force conventional production to fill the gaps with copper fungicides to counteract fungicide resistance. In contrast to the EU Green Deal goals, the intended expansion of organic farming area in Europe would further enhance the use of copper fungicides and hence increase the overall risks of chemical crop protection in Europe.