Pathogenic variability of Didymella rabiei, the agent of ascochyta blight of chickpea in Kermanshah province

Blight disease of chickpea caused by Ascochyta rabiei (Pass.) Lab.is one of the most important chickpea diseases in the world and Iran, which causes huge damages to chickpea farm in the suitable climatic conditions. Study of genetic diversity and various races exist in the different regions would be necessary for resistant cultivars development. In this research physiological races of 28 isolates of A. rabiei which were collected and purified from five region of Kermanshah province during 2012-2013 were determined using seven differential chickpea cultivars (ILC-202, ILC-1929, ILC-5928, ICC-3996, ILC-194, ILC-1929 and ILC-72). All isolates were classified in six physiological races. Among the all isolates, seven isolates (25%) belonged to race 1, Five isolates (17.8%) belonged to race 2, Seven isolates (25%) belonged to race 3, Four isolates (14.4%) belonged to race 4, two isolates (7.2%) belonged to race 5 and three isolates (10.6%) belonged to race 6. Races 1, 2, 3 and 4 with 23 isolates (82.1%) were occurred in all areas of the province while race 6 with high virulence was detected only in one area (Sararood). Investigation of the morphological traits of isolates on CSA (Chickpea sucrose Agar), showed differences in view of diameter, color and form of colony, pycnidium density and pycnidium size among the isolates, but there was not any difference in term of pycnidiospore size.