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Viticulture is a cropping system in which treatment against fungal diseases (in particular powdery and downy mildews) can be extremely frequent. Accordingly, a reduction in antimicrobial treatments and the application of environmentally-friendly compounds are becoming increasingly important for a more sustainable viticulture. In addition to their effect against pathogens, the impact of these products on the quality of the grapes is very important for the oenological industries, but unfortunately at present few data are available. We evaluated the effect of the application of biocontrol products and resistance inducers in the vineyard on the mechanical properties, microbial ecology, technological and phenolic maturity of Vitis vinifera “Nebbiolo” grapes at harvest. The yield and vigor of vines were not influenced by the treatments, nor were the production of primary and secondary metabolites. However, the active ingredients influenced the mechanical properties of the skin (hardness and thickness). A significant hardening of the skin was detected when laminarin and chito-oligosaccharides were used, and sulfur induced a thickening of the skin with potential consequences for wine quality. Furthermore, the yeast community present on grape berries was influenced by the treatments. The abundance of Aureobasidium pullulans, the dominant species on the grape berry, changed in response to the compounds used. In addition, Alternaria sp. was reduced in some treatments with a potentially positive effect on the quality and the safety of the grapes. This study provides an overview of the effect of biocontrol products and resistance inducers on microbial ecology and “Nebbiolo” grape quality, contributing to the establishment of more sustainable and effective defense strategies in viticulture.

Several commercial vineyards, located in Piedmont (Northern Italy), were monitored in order to evaluate the sensitivity of Botrytis cinerea Pers., the causal agent of grey mould, to five classes of botryticides: benzimidazoles, dicarboximides, phenylcarbamates, anilinopyrimidines and phenylpyrroles. Strains of B. cinerea resistant to anilinopyrimidines were easily detected, particularly in 1999, a year characterized by high disease pressure, even in vineyards not sprayed with that class of fungicides. Fludioxonil-resistance, on the contrary, was not detected. Resistance to benzimidazoles and dicarboximides was at previous observed levels. For the first time, resistance to phenylcarbamates was detected in the field. Strains of B. cinerea showing multiple resistance to benzimidazoles, dicarboximides and anilinopyrimidines and maintaining a good level of virulence, as shown by tests carried out on wounded apples, are present in Italian vineyards. Strategies in the use of the botryticides are discussed, in order to avoid a loss of disease control.