Dept. of Horticulture and Crop Sci., Pl. Pathology, Entomology and Alternative Agri-Enterprise Center, OSU Columbus. All the varieties tested in 1996 were evaluated for powdery mildew resistance on two dates. The results are in the Tables below. They can appear on both leaf surfaces, stems and petioles.
Symptoms usually develop first on older leaves.
Mildew on leaves and vines in advanced stage. Lesions cover entire leaf turning it white in color. Some infected areas of the leaf appear as yellow spots. The next stage will be necrosis or death of the leaf which will turn brown. Usually occurs in late August and early September.