D Angeli, C Longa, E Bozza, L Maines, V Simeone, Haya Abou Assaf, Ilaria Pertot

Pathogen resistance to fungicides, concerns regarding pesticide residues and revocation of some widely used fungicides have increased research efforts for developing biocontrol agents of fungal pathogens. Natural fungicides active against grapevine powdery mildew are few and moderately effective. Moreover, no good commercial powdery mildew-resistant grapevine varieties are available. Therefore, development of alternatives to chemical pesticides against Erysiphe necator is of high priority. Efficacy trials were carried out during 2004 and 2005 using bacteria, yeasts, fungi, plant extracts and Electrolyzed Acid Water (EAW) to control powdery mildew under controlled greenhouse conditions. Only few of the tested yeasts, bacteria and fungi were significantly effective in reducing powdery mildew symptoms. Among natural products, only an enzyme based fungicide (KBV 99-01), when sprayed three days after powdery mildew inoculation, was effective. Promising results were obtained with daily sprays of EAW during one week after inoculation and EAW applied in alternation with a yeast suspension.