Study on survey and incidence of collar rot disease of rajma (Phaseolus vulgaris L.) in Barak valley zone of Assam

A survey was conducted during Rabi 2022-2023, to determine the prevalence of collar rot disease of Rajma in three Rajma growing districts viz; Karimganj, Cachar, and Hailakandi in Barak Valley Zone of Assam. Observations were made from 110 numbers of farmer‘s fields under natural condition from three different districts covering 9 blocks with 25 villages. The study revealed that Sclerotium rolfsii, the causal agent of collar rot disease of Rajma is a significant pathological problems in the Barak Valley Zone of Assam. Incidence of collar rot was found in every district under investigation. North Karimganj block in Karimganj district had the greatest disease incidence, with a maximum mean disease incidence of 35.19 percent. This was followed by Borkhola block (34.23%) of Cachar district, Badarpur block (32.20%) of Karimganj district, Sonai block (30.11%) of Cachar district, South Karimganj block (28.93%) of Karimganj district, Salchapra block (26.28%) of Cachar district, Patharkandi block (24.23%) of Karimganj district, Lala Development Block (23.80%) of Hailakandi district and Hailakandi Development block (22.12%) of Hailakandi district. Least collar rot disease incidence was observed in Hailakandi Development block of Hailakandi district with least disease incidence of 22.12 per cent. Different blocks of the districts had varying average collar rot incidence ranging from 35.19 to 22.1 percent.