KANSAL, SANDEEPBHARDWAJ, CHIDEMBRA2019-01-042019-01-042018-10http://krishikosh.egranth.ac.in/handle/1/5810088949ABSTRACT Stemphylium blight caused by Stemphylium vesicarium (Wallr.) E. Simmons is an important destructive disease among various other diseases. It appears every year in moderate to severe form in different garlic growing areas of Solan and Sirmaur districts of Himachal Prdaesh. The causative fungus isolated from infected leaves of diseased plants grew in the form as off white mycelium, which later turned golden brown and finally velvety on PDA. Conidia were oblong to oval, light to olive brown in colour, produced on straight to variously curved cylindrical conidiophores. Thus, based upon morphological and cultural characters, the causative fungus was identified as Stemphylium vesicarium (Wallr.) E. Simmons. The pathogenicity tests revealed peculiar symptoms as small white to yellow flecks which later turned into lesions tan brown in colour and expanded along the leaf blade, giving blighted appearance to the leaves. Epidemiological studies revealed that the temperature of 25ºC, inoculum concentration of 6x104 conidia/ml, leaf wetness period of 72 h and relative humidity of more than 90 per cent were optimum for the rapid progression of disease reflecting significant higher infection rate under artificial epiphytotic conditions. Under field conditions, disease was affected by variation in weather variables, as dry and moist weather coupled with intermittent rains favoured the progression of Stemphylium leaf blight disease. Twelve genotypes were tested against Stemphylium blight disease of garlic. None of the genotypes tested was found immune or resistant to the disease whereas, Kandaghat Selection was found moderately resistant against the disease. In vitro evaluation of fungicides indicated Folicur (tebuconazole), and Companion (carbendazim+mancozeb) as potent mycelial growth inhibitors of S. vesicarium. Field evaluation studies inferred the application of three foliar sprays of Folicur (tebuconazole) @ 0.1 per cent at ten days interval started with the initiation of disease to be most efficacious in limiting Stemphylium blight of garlic (71.5%) and enhancing the bulb yield (145.7q/ha) with ICBR ratio of 1:9.1.ennullThesis