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Reduction of copper-containing pesticides in organic viticulture: investigations into innovative copper formulations with high reduction potential and developing strategies to their specific application to the grapevine
Project
Project code: 2809OE057
Contract period: 01.01.2011
- 31.12.2013
Budget: 126,030 Euro
Purpose of research: Applied research
Copper is prevalently used in organic agriculture in several specialized crops as a plant protection product. Especially largescale specialized cultures like apple, hops and wine are dependent upon copper containing plant protection products to protect their crops against a variety of pathogens. Copper is mainly used against oomycota like the Downy Mildew of hops or grape and the agent of the apple scap (Venturia inequalis).
Using copper in this fashion leads to heavy metal accumulation in soils of these cultures. In highly impacted vineyard soils a negative effect on soil organisms, small mammals and birds has previously been shown by other groups. Large amounts of copper in the soil have been implicated to reduce biodiversity of soil organisms like earthworms and microorganisms. Thus copper as a plant protection agent stands in stark contrast to the idea behind organic farming. This problem is amplifies in organic agriculture as there are literally no alternatives to the use of copper containing fungicides.
In our Project we tested the effect of several different copper salts and copper containing compound on grape Downy Mildew (P. viticola) to identify their copper minimizing potential. Our experiments showed that for an optimal effect against grape Downy Mildew an easily soluble copper salt like copper sulfate combined with a good adhesion to grape leafs yields the best results. Microencapsulation of copper is one way to achieve this. For our experiments copper sulfate was encapsulated in a fat capsule by the Agrolytix GmbH which resulted in our so called CuCaps. In 2012 this compound was ready move into the next phase of testing. An optimization of the release kinetics of copper ions from the capsules gave us slow release capsules. With these we could perform a successful test in the field. The slow release formula guarantees a long lasting effect on leafs. The field test was performed on site at the Blankenhornsberg in fields of the state’s vineyard (Staatsweingut Freiburg) under field and praxis conditions. We could show that the CuCaps had an equivalent effect compared to a commercially available product (Cuprozin progress). Even with a reduced application rate of app. 1.2kg pure copper per year and hectare we still had a good reduction of infection rate and strength. Additionally the CuCaps led to a significantly lower infection rate and strength of flower clusters and grapes compared to the commercially available product. We also tested the rainfastness under laboratory conditions. The results showed good adhesion and a good resistance to being washed off.
During the project several cooperation partners were convinced to also use the CuCaps in their respective projects. Dr. Christian Scheer from the “Kompetenzzentrum Obstbau-Bodensee” and Dr. Florian Weihrauch from the “Landesanstalt für Landwirtschaft” agreed to test our CuCaps in their cultures. Both presented their positive findings during the “Kupferfachgespräch” in 2012 and 2013. This shows that the CuCaps could be used not only in viticulture but in other crop plants as well and could add to the efforts of minimizing the introduction of copper into the soil in organic farming in general.
We also studied substances which could be used as additives to or replacements of copper con-taining plant protection agents. Our experiments showed that the addition of wettable sulfur (Netzschwefel) can increase the efficiency of copperbased plant protection substances but also shows an effect against P. viticola. We also found that an ethanolic extract of hops had a protec-tive effect against the Downy Mildew but this was only transient. Another good candidate as a replacement or additive substance was hexadechylphosphocholin which was a result of cooperation with the clinic for tumor biology in Freiburg. This substance was tested under field conditions and showed a good effect.
Additionally we also looked at a wide variety of other natural products which showed antimicrobial properties in our acetic acid bacteria screenings but none of those had a sufficient or stably reproducible effect on P. viticola. Thus they were excluded from further analysis.
All things considered this project resulted in the CuCaps as a compound which could lead to a fur-ther decrease in copper application in wine and other crops. It also yielded three substances (wettable sulfur, hops extract, HePC) which could further this process as additives or replacements and should be analyzed further.
Section overview
Subjects
- Crop Protection
Framework programme
Federal Organic Farming Scheme and other forms of sustainable agriculture (BÖLN)
