Title : Evaluation of organic products for the control of foliar diseases in resistant grapevine varieties
Abstract:
Erysiphe necator and Plasmopara viticola are the causal agents of two of the main fungal diseases responsible for important economic losses in grapevine. To control these diseases, numerous chemical treatments are applied, favouring environmental deterioration and endangering the sustainability of the vineyard. To achieve the objectives of the European Green Deal, one environmentally friendly strategy is the introduction of varieties with resistance genes to fungal diseases. Therefore, various initiatives have led to the development of more than 150 new cultivars as a result of the introgression of resistance genes from American and Asian Vitis species with different genetic backgrounds of V. vinifera. The most recent ones contain a wide range of V.vinifera genome (75% to 94%) trying to preserve the quality characteristics of their European parents. These genes do not provide total resistance to pathogens and some treatments are needed. In this context, the objective of this work is to implement a sustainable agroecological strategy with the combination of resistant varieties with 6 basic substances, low risk products with less environmental impact. This objective is framed within the Shield 4 Grape project (HORIZON-CL6-2023-BIODIV-01-14). Firstly, the we evaluated the growing capacity of the 2 pathogens, E. necator and P. viticola, in 9 PIWI (Rpv3 and/or Rpv12 genes for downy mildew and Ren 1 for powdery mildew) varieties in in vitro assays. The in vitro tests were performed on detached leaves previously sterilized, the inoculation of powdery mildew was done with a vacuum tower by massive inoculation recording the growth of the fungus at 7 and 14 days, and for downy mildew by dilution at a concentration of 105 ufc/ml, collecting the results at 5 and 7 days. For powdery mildew, at 7 days, mycelium growth, without development of conidiophores, was observed in all varieties, and at 14 days, the lowest incidence was recorded in S.Rytos, Fleurtai and Soreli. For downy mildew, C.Eidos, S.Kretos, S.Nepis and Soreli were the most resistant, Secondly, Soreli and S.Rytos were selected to implement an integrated pest management assay in the greenhouse, with Viura and Chardonay as controls. Potassium hydrocarbonate, lecithin, chitosan and extracts of orange oil, salix and equisetum were used at the doses recommended by the manufacturer. The evaluation of disease incidence was made from 10 days after inoculation for E. necator and 5 days for P. viticola until the date of action of the product. Results from the IPM experiment in the greenhouse will be discussed.
