Healthy vines in organic viticulture, reduction of the use of copper in plant protection and at the same time a high level of production security for winegrowers: the Vitifit research project was launched in Germany in June 2019 with these ambitious goals. For the first time ever, the most important German training and research institutes and associations have joined forces with technology providers and wineries. They can access a considerable amount of funding for this: After all, the Federal Ministry of Food and Agriculture (BMEL) is funding the research project with 6.3 million euros as part of its "Federal Programme for Organic Farming and Other Forms of Sustainable Agriculture" (BÖLN).
In addition to the Geisenheim University of Applied Sciences, the Weincampus Neustadt, the Friedrich-Alexander University Erlangen-Nuremberg, the Julius Kühn Institute in Siebeldingen, the Dienstleistungszentrum Ländlicher Raum (DLR) Rheinhessen-Nahe-Hunsrück and the DLR Rheinpfalz are involved. The Freiburg Viticulture Institute and the Bavarian State Institute for Viticulture and Horticulture in Veitshöchheim round off the list of state institutions. In addition, there are the organic associations Bioland, Demeter, Ecovin and Naturland, three technology companies as well as some organic wineries that act as pilot and demonstration farms.
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The project is pursuing three research priorities - the reduction of copper to combat downy mildew (Peronospora) is one of them. "Since potassium phosphonate is no longer permitted in organic viticulture, only copper remains to control peronospora," explains Randolf Kauer, professor and project leader at Geisenheim University. The systemically acting plant protection agent is considered a reliable tonic for vines and was also approved in organic viticulture. The positive effect: potassium phosphonate shows high efficacy against infections with downy mildew. However, with the EU classification as a plant protection product, the active ingredient was removed from organic approval after long, sometimes heated discussions among those involved. The reason given by the expert group was that the agent was not of natural origin and that residues could possibly get into the product. These arguments left many organic producers perplexed. "Yet the degradation products of potassium phosphonate are toxicologically irrelevant," Randolf Kauer counters. His goal for Vitifit is to improve the chances of controlling downy mildew. His claim: In the long run, 2.5 or even only two kilogrammes of copper per hectare and year should become a realistic value, possible in any weather.
Many organic winegrowers find it difficult to use copper alone to combat downy mildew and powdery mildew. It remains a heavy metal that accumulates in the soil over time and has an impact on soil fertility. Copper not only has an antibacterial effect, it also stops the development of microorganisms. "In Germany, we are basically very critical of copper," Randolf Kauer reports. While in the EU the total amount of copper was reduced from six kilograms per year and hectare to four kilograms two years ago, Germany has already minimised the use of copper to three kilograms since 2009. "Ecovin has specified this amount since 1985," emphasises the Geisenheim University professor. In years like 2016 with enormously high peronospora pressure, it means for many organic winegrowers to suffer total crop failure - or to give up organic winegrowing. "For us, it must therefore be about giving winegrowers who practise organic viticulture production security," Randolf Kauer emphasises the concern of the research project.
German organic winegrowers have long been world champions in copper reduction: "In the past few years, we were even able to stay below two kilograms per hectare due to weather conditions." But it doesn't always have to stay that way, so three kilograms is currently the absolute pain threshold - and sometimes it's too little. "For many wineries, this is a reason not to convert production to organic," Randolf Kauer knows. They consider the risk of having no room for manoeuvre in case of doubt and having to accept harvest losses or failures too high.
Thus, the experts in the project are looking for completely new ways to combat downy mildew. One approach comes from breeding fungus-resistant grape varieties. "We now know the mechanisms that control resistance in the newly bred grape varieties," Randolf Kauer explains the initial successes. By extracting these secondary plant constituents, the so-called stilbenes, they hope to open up new opportunities: for example, for use as organic plant protection agents. Another approach is to use methods to slow down the release of the active ingredient in copper. With the help of "encapsulation", a kind of fat coating of the active ingredient, the adhesion of the plant protection product to the leaves is to be improved and the release of the active ingredient is to be extended over a longer period of time. "We've already had some promising results," says Randolf Kauer optimistically. However, what works in the greenhouse and in field trials still has to prove itself in practice.
The project is also pursuing a third strategy against peronospora: combating the fungus with UV light. "Anyone who spends too much time in the sun knows what this light can do," reports the professor of organic viticulture. In Geisenheim, researchers have already gained experience in killing fungal pathogens with UV-C radiation. "At the moment, the main thing is to find the right dosage so as not to damage the leaves or the grapevines The researchers are also working on a classic improved cultivation technique. This involves optimising the timing of defoliation or soil coverage in order to remove disease pressure from the vineyards. This is closely linked to a second area of research: the Vitimeteo forecasting model already provides fairly accurate data for planning the use of plant protection. "For us, it is a matter of adapting this model to the needs of fungus-resistant grape varieties. They have a completely different damage threshold than the classic grape varieties, which is very interesting," says Kauer.
The fungus-resistant grape varieties are the third focus of the Vitifit project. "When you talk about copper reduction, you also have to talk about piwis," emphasises the project manager, "the Institute for Grapevine Breeding Geilweilerhof has done a lot of pioneering work here." For example, the vine breeders now know very precisely on which chromosomes the genetic resistances are located. With new results from cross-breeding, they could therefore directly check which and how many resistance genes are present. "This saves years of trial cultivation and has nothing to do with genetic modification," Randolf Kauer enthuses. In addition, the researchers would always identify new resistance genes.
Randolf Kauer sees the greatest advantage of the research project in the joint work of the experts in different specialised disciplines. "There are many people involved, everyone has his or her focus. The most important thing about this project is that it brings all the results together." For the time being, the project was approved for three years - but it was clear from the beginning that this was likely to be too short. That's why those involved applied for two more years right at the start. The decision is still open. Randolf Kauer is confident that they will be granted.