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Strategies to reduce and avoid copper in organic potato production. Subproject 2: Potential of copper substitutes and new copper formulations
Project
Project code: 2809OE114
Contract period: 01.07.2011
- 31.08.2015
Budget: 216,966 Euro
Purpose of research: Applied research
In organic potato production late blight of potato (Phytophthora infestans) can only be effectively controlled through the use of copper fungicides. Its accumulation in the soil and potential negative effects on non-target organisms make a reduction of copper usage necessary. The starting point of Phytophthora epidemics often are infected planting tubers from which form primary infection sites develop. Spores washed onto the soil from infected plants infect the new tubers and thus the planting material for the next season. Within the course of this project ways to reduce the primary infestation rates in organic potato production were to be found. In laboratory tests, over 20 preparations were tested for their suitability as alternatives to copper as a foliar treatment. For some substances efficiencies similar to that of the copper fungicide could be observed, in both abscised leaf as well as in potted plant assays. The most effective preparations (chitosan, knotweed, liquorice, horsetail, and citrus, as well as a foliar fertilizer with low copper content) were also tested in field trials. Liquorice, chitosan, horsetail and the copper fertilizer showed some activity against leaf infection in these tests. The combination of reduced amounts of copper with an alternative product in some cases reached efficiencies almost equal to that of copper alone, depending on start and progress of the epidemic. Seed tuber dressings before storage or before planting also can provide protection against Phytophthora infections. In laboratory experiments with artificially infected tubers many alternative seed dressings brought an increase in the survival rate of the plants, or a reduction of brown rot on the stored tubers. Phosphonate, chitosan and a yeast preparation showed the best effect. In field trials an effect on the primary infection could not be clearly demonstrated, however, in 2012 plots with treated tubers showed lower late blight infection rates, and in 2014 lower rates of failing tubers. Together with other agronomic and technical measures such as mechanical or thermal leaf reduction, foliar and seed treatments with certain alternative preparations in exchange for or in addition to copper could be part of a late blight management strategy for organic potato production.
Section overview
Subjects
- Crop Protection
- Vegetable Gardening
- Organic Farming
Framework programme
Federal Organic Farming Scheme and other forms of sustainable agriculture (BÖLN)
