Small dark, angular, necrotic lesions occur on the upper surface of grapevine leaves. On the lower leaf surface, the lesions are covered by sporulating pustules (Weinert et al. 2003). The disease can cause premature defoliation and reduce the fruit quality and yeld (Ono 2000).
The fungus:
P. euvitis is heteroecious and macrocyclic. Uredina on Vitis, hypophyllous, minute, scattered or aggregate in small groups, subepidermal, becoming erumpent, surrounded by cylindrical to weakly incurved, evenly thin-walled or dorsally thick-walled (1.5?4 µm) paraphyses of 30?75 µm high. Urediniospores obovoid, obovoid-ellipsoid or oblong-ellipsoid, 15?29 x 10?18 µm, the wall ca 1.5 µm thick, echinulate with 6 scattered or rarely 4 equatorial germ pores. Telia on Vitis, hypophyllous, crustose, brown to blackish brown, often confluent, subepidermal, applanate. Teliospores more or less regularly arranged in 3?5 layers, oblong to oblong-ellipsoid, 13?32 x 7?13 µm, the wall thin, pale brown at the top layer spore. Basidiospores reinform, 8.2?11.4 x 5?8 µm (Ono 2000).
