Adiver, S.S.Nadumani, Parashuram2022-01-272022-01-272017-07https://krishikosh.egranth.ac.in/handle/1/5810181236Studies on grape powdery mildew caused by Uncinula necator (Schw.) Burr, was carried out at Department of Plant Pathology, College of Agriculture, Vijayapur and farmer field, Hittinahalli during Rabi 2016-17. The survey during 2016-17 revealed that, the disease was noticed in varying intensities in three districts; maximum disease severity was in Vijayapur (50.18 PDI and 24.17 PDI) followed by Bagalkote (27.18 PDI and 10.47 PDI) and Belagavi (20.00 PDI and 8.23 PDI) was recorded least disease severity during foliage (vegetative) and fruiting stage respectively. The pathogen produced conidia in chains and they were ellipsoid or ovoid to cylindrical. They were non septate and hyaline in nature which measured about 29-42×12-20 µm. Maximum conidial germination was observed at 24 hrs after incubation. Temperature range of 20 to 25 0C, relative humidity of 80 to 85 per cent and slightly acidic pH (5.0 -6.0) were found congenial for conidial germination of U. necator. The maximum per cent conidial germination (45.50 %) was recorded in indole acetic acid (IAA) fallowed by gibberellic acid (GA) (36.50 %). Least conidial germination was observed in ethylene (9.66 %). Phenol content was higher in diseased leaves (4.61 mg/g) and fruits (3.71 mg/g) as compared to the healthy leaves (3.95 mg/g) and fruits (3.30 mg/g). The reducing sugars (3.25 mg/g and 74.51 mg/g) total sugars (4.74 mg/g and 84.75 mg/g) and protein (7.41 mg/g and 2.57 mg/g) contents were higher in healthy leaves and fruits as compared to the diseased leaves and fruits. Azoxystrobin 23 EC (99.66 %) was shows highest inhibition of powdery mildew of grape caused by of U. necator followed by hexaconazole 5 EC (98.00 %) and Chlorothalonil 75 WP (43.33 %) shows least inhibition under in vitro conditions. Azoxystrobin 23 EC at 0.05 per cent found to be the best fungicide recoding least incidence (4.00 %) followed by hexaconazole 5 EC (6.67 %) and propiconazole 25 EC (10.00 %) at 0.1 per cent after four spray under in vivo conditions.EnglishThesis