Nutritional and physiological requirements for growth and sclerotial formation of Sclerotinia sclerotiorum causing white rot of capsicum

Sclerotinia sclerotiorum was isolated from infected stems and fruits of capsicum crop grown under green house conditions. Natural, semi-synthetic and synthetic media were evaluated for growth and sclerotial formation by the pathogen. The number of sclerotia as well as rate of colony growth was maximum (29.09mm/day) on potato dextrose agar. The maximum sclerotial size and weight was supported by oat meal agar. Czapek's dox agar induced fastest sclerotial initials formation followed by potato dextrose agar, Richard's agar and french bean seed agar. The optimum temperature for maximum rate of colony growth, length, breadth and cummulative weight of sclerotia per Petri plate was found to be 20°C, whereas, maximum number of sclerotia were formed at 15°C with smaller dimensions and weight compared to those formed at 20°C. Fastest sclerotial initials were observed at 25°C followed by 20°C in case of potato dextrose agar and oat meal agar. Both mycelial growth and sclerotial production decreased with increase in temperature till 30°C. Optimum pH for maximum vegetative growth and sclerotial production of S. sclerotiorum was 5.0, whereas, for getting maximum size of sclerotia, pH 6.0 was found to be optimum.