Bean Anthracnose (Colletotrichum lindemuthianum) in Kashmir: Epidemiology and Yield Loss Assessment

Background: The present study is region specific carried out to see the relation of bean anthracnose with weather in Kashmir and also to assess the yield loss in bean vis-à-vis anthracnose. Such studies form basis for deciding disease suppressive crop geometry and also sowing date alterations besides helping in disease predictions. The yield loss study in particular reveals the importance of a disease before any management strategies are worked out. Methods: Epidemiology was conducted under natural epiphytotic conditions using a susceptible bean cv. Shalimar Rajmash-1 for recording disease development at weekly intervals. Yield loss assessment was also recorded on Shalimar Rajmash-1 where different disease levels were created by inoculating at different phonological stages after maturity the crop stand disease free. Conclusion: During cropping season, the incidence and intensity of bean anthracnose developed to the extent of 77.06 and 54.51 per cent, when average temperature, average RH and weekly rain fall ranged from 16.6-23.8oC, 62.2-76.5 per cent and 1.7-48.2 mm, respectively. However, the highest periodic increase in disease incidence (12.62%) was recorded during 24th standard metrological week which coincided with highest rain fall and the increase in periodic disease intensity was higher ( greater than 10%) when RH was above 70 per cent. The yield loss in bean vis-a-vis variable levels of disease as created by inoculating different unit population of bean plants at different phenological stages revealed significant and positive correlation of bean anthracnose and yield loss. Highest yield loss (68.42%) was recorded in populations where the disease started at 1st trifoliate stage which then reached maximum intensity of 81.09 per cent at physiological maturity. The terminal disease intensity in population where disease started at pod filling was significantly low (18.59%) and caused least yield loss of 10.95 per cent. The study reveals that bean anthracnose caused significant yield loss when it appeared at any stage upto flowering.