Study of pathogenicity diversity Colletotrichum lindemuthianum (Sacc. and Mgnus) Briosi and Cav. agent bean anthracnose and resistant evaluation of common bean cultivars

Bean anthracnose caused by Colletotrichum lindemuthianum (Sacc. and Magnus) Briosi and Cav., is one of the major diseases of common bean in relatively cool, wet cultivation areas of tropical and temperature regions. Crop losses can be severe or total, especially when susceptible cultivars are grown in a conductive environment for disease. In this study, first different fungal isolates were obtained from the west and north areas in Iran, purification and pathogenicity done on susceptible cultivar “Talash” with spore suspension with concentrations of 1-2 ×10 6 spores/ml on leaves in the greenhouse. Then the virulence of isolates conducted like pathogencity method on Talash cultivar. Disease severity index, 15 days after the spore spraying was rated using the method described by Van Schoonhoven and Pastor-Corrales. A total of 11 isolates C. lindemuthianum were obtained based on the results of sampling from different regions that had mostly high virulence, with different severity indices of the disease, ranging between 22.2 to 98. In reaction study of 40 bean cultivars or genotypes to causal agent in greenhouse conditions, six cultivars (Naaz, Pachebaghela- ragehghermez, Almas, Shekoofa, Daneshkadeh, Dorsa) and four genotypes (920040, 940040, 21676 and 31167) with infection degree less than 3 showed resistant “R” (25% of all varieties and genotypes) whereas eight genotypes or varieties showed moderately resistant reaction “MR” and the rest were considered as susceptible “S”.