Preliminary tests in field conditions of alternatives substances against grape downy mildew in organic farming


Abstract: Within the context of research of alternatives to the use of copper against thegrapevine downy mildew (Plasmopara viticola), screening tests have been carried out to assessthe activity of potential products either as fungicidal or as elicitors of plant defense and/orresistance. Three hydroalcoholic solutions of plant extracts Salix alba, Equisetum arvense,Artemisia vulgaris and three aqueous ones of Frangula alnus, Rheum palmatum and of microdosesof D-fructose (100ppm) were sprayed single on leaves or associated with 100g/ha ofcopper hydroxide. Their efficacies were evaluated versus 600g/ha of copper hydroxide and anuntreated control. The trials were randomized and carried under shading nets on two vinecultivars planted in individual pots: Vitis vinifera cv. Alphonse Lavallée grafted onto110 Richterand V. vinifera cv Muscat de Hambourd grafted onto 161-149 Couderc. In 2011 the productefficacies expressed by the attack frequencies and intensities of P. viticola, showed that thesolutions of F. alnus, E. arvense and of D-fructose associated with copper 100g/ha, were aseffective as copper hydroxide 600g/ha. They significantly reduced attack rates versus theuntreated control. A. vulgaris extract had no visible effects. Further experiments will beconducted in 2012 to corroborate these interesting data.

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