Studies on pathogenicity of grey mildew (Ramularia areola Atk.) in Bt cotton

Abstract

In Maharashtra, grey mildew is becoming great threat to cotton growing areas in Marathwada, Vidarbha region and other cotton growing tract. It has been reported that the grey mildew disease reduces yield as much as 38 % from Akola (Shivankar and Anvikar, 1995). The occurrence of disease also been reported from Tamil Nadu, Andhra Pradesh and so many cotton growing states in India. Isolation of fungus from grey mildew infected leaves was made by tissue transfer method. Diseased leaves (grey mildew) of cotton collected from various fields during the survey were brought to the laboratory and washed thoroughly in running tap water. The maximum disease intensity was recorded in Gokunda village of Kinwat Taluka (14.50%) followed by Hiwar of Mahoor Taluka (13.70%). The intensity of grey mildew of cotton in different places of Nanded district ranged from 7.30% to 14.50%. Pathogenicity of Ramularia areola Atk. was successfully proved on Bt cotton cv. Jadoo BG II under controlled conditions of screen house.