Grapevine resistance induced by treatment with Trichoderma harzianum T39. Downy mildew severity (%) was assessed on Vitis vinifera Pinot Noir control plants (C) and plants treated with T. harzianum T39 (T39). Mean severity scores and standard errors for six replicates are presented. Treatments followed by different letters are significantly different according to Tukey’s test (P < 0.05). Photographs show sporulation of downy mildew on representative leaves.