Interdisciplinary evaluation and integrated analysis of

Climatic changes pose major challenges for viticulture due to prolonged periods of heat and drought as well as unusually high rainfall. This results in increased radiation and drought damage as well as enormous microbial and entomological damage to the grapes, which is associated with economic losses for winegrowing businesses. As part of a project of the Research Ring of German Viticulture (FDW), which is funded by the Rhineland-Palatinate Ministry of Economic Affairs, Transport, Agriculture and Viticulture (MWVLW), the interrelationships between the abiotic and biotic damage caused by climate change are to be analyzed with regard to viticultural measures and grape variety selection, and the effectiveness of sustainable products and their multiple uses evaluated. A holistic solution strategy is then to emerge from both aspects, which will make it possible to react preventively to upcoming climate-related challenges.

Sunburn is the result of a complex interplay of temperature, direct sun exposure, wind, water supply to the vines and row orientation, which can cause varying degrees of damage depending on the grape variety and stage of development. Sunburn occurs particularly frequently when the grapes are exposed to unexpectedly intense sunlight without having already adapted, which can be attributed to both a change in the weather and an incorrectly timed defoliation.

In addition to damage caused by abiotic factors, various pathogens are also appearing more frequently as a result of climate change. The pathogen that causes gray mould rot(Botrytis cinerea) is the most important cause of grape rot in viticulture. The fungus infects the grapes primarily via wounds in the grape skin. In addition to bruising, sunburn, hail, previous infestation by powdery mildew(Erysiphe necator), bird or insect damage, but also egg laying by the invasive cherry vinegar fly(Drosophila suzukii) can lead to injuries to the berry skin. This opens up entry points for other secondary pathogens such as the pathogen that causes green rot(Penicillium expansum) or the pathogens that cause vinegar rot, acetic acid bacteria(Acetobacter spec.) and wild yeasts.

In this respect, D. suzukii represents a further, decisive pest of viticulture, whose damage potential is greatly increased by these interactions in years with high rainfall. To lay their eggs, the females use ripening and ripe grapes of red grape varieties, which they scratch with their ovipositor to then push the egg under the skin of the berry. Curative infestation control is difficult, which is why prophylactic measures are usually preferred, which also minimize the risks for non-target organisms. Berries that have already been damaged by fungi or other factors in turn encourage infestation by the pest and its native relatives, which can only use pre-damaged fruit to lay their eggs.

In order to keep yield and quality reductions to a minimum, holistic concepts must be developed that take into account both abiotic and biotic stressors and their interactions. With regard to the European Union's "Green Deal", the focus is on new solutions and products that reduce a large number of current problems as synergistically as possible in a sustainable manner in order to halve the use of chemical pesticides by 2030.