Vol. 11, Issue 2 (2022)

Author(s):
Sunaina Varma and Data Ram Kumhar

Abstract:
Root Rot of chilli caused by Rhizoctonia solani Kuhn is one of the more severe yield destabilizing factors causing serious yield losses each year. In recent years, Root Rot of chilli is becoming more prevalent in agricultural areas. An experiment was conducted in 2016-17 in which, a series of fungal isolation, purification, identification and pathogenicity test from the infected plant parts were done. The infected samples of Rhizoctonia solani Kuhn incitant of root rot were collected from chilli diseased fields of different districts of Rajasthan viz. Sri Ganganagar, Hanumangarh, Bikaner (Agricultural Research Station and farmer’s field) and Jaipur. These infected plant samples were brought to the laboratory for microscopic examinations and for further investigations. For the identification of fungus, Koch’s postulates were proven. Isolation was made from infected plant parts. The culture of Rhizoctonia solani Kuhn was purified by hyphal tip culture method. The identification of the test pathogen was confirmed by cultural characteristics as well as shape of conidia and conidiophores. The pathogen Rhizoctonia solani Kuhn causing root rot of chilli was isolated from the diseased plant, purified on PDA and pathogenicity was proven under screen house condition. All the isolates were pathogenic and among these isolates, Sri Ganganagar isolate was most virulent. Mostly clearly marked patches firstly a sudden wilting or chlorosis of the leaves takes place from outside inwards and the infected plant often show stunted growth. In the upper third of the root body, often immediately below the soil surface, greyish-brown to black rotten spots or fissures become visible first of all only on the root surface. In the advanced stage, these rotten spots merge into one another. A cross-section through the root body shows a clear division between healthy and infected tissue. Root Rot starts just below the soil surface and spreads over the whole root with growing disease development. In the affected patches often all stages of infection are found together.