Evaluation of copper alternative products to control grape downy mildew in organic farming

The aim of this work was to investigate the efficacy of copper alternative products of natural origin against Plasmopara viticola to reduce or replace the use of copper in organic farming. The identification of new active and sustainable substances is in fact of priority importance because of the environmental impact of copper. The activity of the products was investigated in laboratory and greenhouse conditions. The laboratory tests included the evaluation of the effect of products on mycelial growth, using artificially inoculated leaf disks, and on sporangial germination. The greenhouse experiments were carried out on grape seedlings cv. Malvasia di Candia treated with products and inoculated, after 24 h, with sporangial suspension of P. viticola. The results both of laboratory and greenhouse tests showed inhibitory activity performed by several botanicals (licorice leaf extract, Yucca schidigera extract), by ALD1901 product, a derivative from Saccharomyces cerevisiae yeast, by Vacciplant formulation containing laminarin and by inorganic products as potassium hydrogen carbonate and MenoRame formulation based on micro-doses of copper and zeolites. The identification of sustainable approaches to manage grape downy mildew is very important to enhance the quality of organic production.