VARIABILITY OF Pythium aphanidermatum (EDSON) FITZP AND ITS MANAGEMNET

Tobacco (Nicotiana tabacum L.) is a key non-food crop of the Solanaceae family, valued globally for its leaves. It significantly contributes to revenue, export earnings, and employment. Major producers include China, India, the USA, and Brazil. India ranks second, producing 12.3% of global tobacco, with cultivation concentrated in states like Andhra Pradesh, Gujarat, and Karnataka. Gujarat ranks second in area (1.74 lakh ha) and production (5.19 lakh tons), primarily in districts like Anand, Kheda, and Mehsana. Damping-off, caused by P. aphanidermatum, is a critical nursery disease. Studies (2019-2021) revealed variability in pathogen isolates, cultural and molecular characteristics, and management strategies. Seventeen isolates were identified, with hydroponic inoculation being the quickest method for proving pathogenicity. Morphological variability included differences in mycelium and oospore size. Molecular studies showed genetic diversity, with isolates clustering into two groups. In vitro studies of nine fungicides showed azoxystrobin, metalaxyl combinations, and others achieving 100% inhibition, while Bacillus subtilis provided the highest biocontrol efficacy (64.16%).