Survey and morpho-cultural variability of Chilli root rot pathogens

Abstract:

An extensive field survey was conducted during kharif 2025 in ten chilli-growing villages across major production districts of southern Rajasthan to assess percent disease incidence and collect representative pathogen isolates. Typical symptoms of Root Rot of Chilli include yellowing and wilting of plants, followed by brown to dark-brown lesions on roots and the collar region. The roots become decayed and rotten, resulting in poor plant growth, easy uprooting, and, under severe infection, complete drying and death of the plant. Root rot percent disease incidence ranged from 23.46 to 39.50%, with the highest incidence recorded in Udaipur and the lowest in Banswara. Initial disease symptoms were observed 15-20 days after transplanting, indicating early establishment and widespread occurrence of the pathogen in the region. Ten isolates of Rhizoctonia solani exhibited marked cultural and morphological variability on +potato dextrose agar. Radial growth mycelium was ranged from 57.20 to 90.00 mm, categorizing isolates into slow, moderate and fast-growing groups. Hyphal width varied from 2.73 to 7.69 µm, the number of septa between branches ranged from 1 to 7 and sclerotia production ranged from 5 to 60 sclerotia mm. The substantial variability observed among isolates indicates considerable diversity within the pathogen population, which may influence disease epidemiology and the development of effective management strategies.