Field evaluation of new plant protection products against Plasmopara viticola

One of the most dangerous fungal diseases in viticulture is downy mildew. Copper-based active ingredients have been used for a long time to protect vines against Plasmopara viticola and they have always maintained an important role in the defense of vines especially for organic production. On the other hand, copper accumulates in the soil causing toxicity with negative consequences on plants and soil fauna. For this reason, new formulations with lower copper content have been considered. In recent years, foliar fertilizers have been studied, in particular those based on phosphites that, along with the nutritional function, stimulate the production of phytoalexins. Those metabolites cause the induced systemic resistance and act directly in the break of cell membranes of pathogens. This study aims to investigate the efficacy against downy mildew of a commercial product based on phosphites and of a new copper-based foliar fertilizer, where copper is chelated with gluconic acid and aminoacids of plant origin. Based on present results, phosphites significantly reduced the infection, without anyway achieving the defense effectiveness of the copper-based treatment however they ensure a significant reduction of the doses of copper necessary to achieve adequate levels of vineyard protection.