Cultural and Physiological characterization of Sclerotium rolfsii Sacc. and Fusarium solani (Mart.) Sacc. causing Wilt of Jasmine

Abstract

Jasmine (Jasminum spp.) is an important commercial flower crop, and wilt disease reduce plant establishment and productivity. This study was undertaken to characterize the cultural and physiological requirements of Sclerotium rolfsii Sacc. and Fusarium solani (Mart.) Sacc. associated with wilt of jasmine in Northern Karnataka. The pathogens were isolated from wilt-affected jasmine plants and identified based on their cultural and morphological characteristics. Among the different solid media evaluated, Potato dextrose agar (PDA) supported maximum radial mycelial growth of both S. rolfsii (7.13 cm) and F. solani (6.80 cm). Similarly, Potato dextrose broth (PDB) was the most suitable liquid medium, producing maximum dry mycelial biomass of 0.93 g in S. rolfsii and 1.58 g in F. solani. In the physiological studies, maximum mycelial biomass of both pathogens was recorded on the 12th day of incubation, with 5.54 g in S. rolfsii and 3.01 g in F. solani. The optimum temperature for mycelial growth was 25°C for S. rolfsii (0.66 g) which was statistically on par with 30°C (0.65 g), while F. solani showed maximum growth at 30°C (1.57 g). S. rolfsii recorded maximum biomass at pH 6.0 (0.559 g), whereas F. solani showed maximum growth at pH 5.5 (1.356 g). Both pathogens exhibited reduced growth under highly acidic and alkaline conditions. The study provides useful baseline information on the cultural and physiological requirements of the major wilt pathogens of jasmine, which can support further investigations on their biology and disease management.