“Integration of plant resistance, cropping practices, and biocontrol agents for enhancing disease management, yield efficiency, and biodiversity in organic European vineyards – VineMan.org” - FINAL PROJECT REPORT

Summary

The Project aimed at improving disease control, which is one of the main and most difficult tasks in organic viticulture, integrating plant resistance against pathogens, cropping practices, use of weather-driven disease models, and use of biocontrol agents (BCAs). All these aspects were firstly considered separately in each WP by the competent partners, then efforts were made to develop innovative vineyard management strategies that consider all these aspects.
All plants have an innate immunity against pathogenic fungi and oomycetes that is triggered by pathogen associated molecular patterns (PAMPs). Repeated application of these molecules or their structural analogues can activate and enhance the innate defence response against a following infection by pathogens. During the project, 85 substances were tested, 26 were able to induce a pH-shift or demonstrated to have some cytotoxic activities, 11 were further analysed in pathogen-leaf-disc assays and demonstrated to reduce downy mildew sporulation. One substance achieved promising results also in field experiments.
Different methods for manipulating vegetative growth, canopy density, and fruit exposure were evaluated as a means for making the microclimate less favourable to pathogens and more ideal for the ripeness of the grapes. The first leaves of each shoot were removed at pre-flowering (ELR) and at pre-veraison, and compared to control vines in Italian, Spanish and Austrian vineyards. ELR was effective in reducing bunch sensitivity to grey mould by reducing bunch compactness and increasing berry skin thickness. Both treatments did not affect the titratable acidity of the musts, while ELR increased the tartaric acid suggesting the possibility to obtain more balanced wines by preserving acidity. Above-bunch-zone leaf removal applied at pre- and post-veraison was also tested on potted vines and compared to untreated vines. The results are very promising in that defoliation was effective in temporarily delaying technological maturity without affecting bunch colour and the content of phenoles. Other treatments, such as anti-transiprant application and “cutting off parts of bunches” were also tested.
Existing models for predicting plant disease outbreaks/epidemics were evaluated for their ability to support decision-making about crop protection, based on the presence of favorable environmental conditions and/or biological information concerning the disease and/or the host plant. Mechanistic, weather-driven models for downy and powdery mildews were implemented in a web-based platform provided by Horta s.r.l., able to produce decision-aids for crop protection in organic viticulture.
Fitness and efficacy of biocontrol agents, representing formulations of bacteria and fungi already registered in Europe, were evaluated in relation to grape pest and disease control under organic practices. Strain-specific detection systems were developed and tested in controlled and natural conditions. Experiments in controlled and natural conditions were performed to test the compatibility of different BCAs and inorganic fungicides for mixed or sequential application and it was demonstrated that sulphur can enhance the efficacy of the product SerenadeTM.
Two innovative management strategies were designed, evaluated through an ex-ante assessment, and tested in different experimental vineyards set up in Italy, Austria, Germany and Slovenia. A first “risk-adverse strategy” is based on the combination of: i) fall treatments with the hyperparasite Ampelomyces spp. for the reduction of the overwintering chasmothecia of Erysiphe necator, ii) the web-portal with models for the prediction of downy and powdery mildews to schedule copper and sulphur treatments at label dose during the season; iii) use of BCAs for the control of grey mold. A second “risk-seeking strategy” is based only on: i) low-dose copper and sulphur applications according to the models and ii) early leaf removal for the control of grey mould. In general, the use of epidemiological models allowed a significant reduction of fungicides, with a consequent reduction of the costs for disease management and the ecotoxicity risk, as well as an increased social acceptability of the vineyard management.
Finally, to test whether the innovative management strategies can increase overall numbers of species inhabiting the grapevines, appropriate culture-depended and culture-independent methods were implemented and applied on samples form the experimental vineyard in Slovenia. Unfortunately, the applied methods could not show that the different management strategies had a significant effect on the fungal species profiles, but very interesting fungal species were detected and the retrieved culture collection represents an important resource for future studies.