Indian Phytopath. 52 (4) : 389-392 (\999) Characterization of pathogenic variability in Colletotrichum truncatum in Himachal Pradesh

ABSTRACT: Virulence pattern of the eleven isolates of Colletotrichum truncatum was studied on arbitrarily selected set of J2 urdbean lines to be used as differentials. Based on the reaction of test isolates on differentials, these were grouped in six pathotypes. Reaction type of different isolates was also studied on related legumes. The pathogen attacked all the eleven related leguminous hosts. However, Parbhat cv. of arhar (Cajanus cajan) was immune since none of the eleven isolates showed compatible reaction on this cultivar. The pathogen was found to have a wide host range among edible legumes grown locally. Key words: Variability, Colletotrichum truncatum, urdbean, edible legumes, pathotypes Urdbean (Vigna mungo (L.) Hepper) is attacked by a variety of fungal and viral pathogens. Among these, Colletotrichum truncatum is a destructive leaf spotting pathogen which normally preceeds the attack of Cercospora spp., the other virulent pathogen of the crop under high rainfall conditions (Kaushal, 1985). C. truncatum is a highly unspecialized pathogen which also attacks many seed and forage legumes notably soybean (Glycine max), lentil (Lens culinaris), mungbean (Vigna radiata), cowpea (V. unguiculata), horsegram (Macrotyloma uniflorum), limabean (Phaseolus lunatus), Vicia sativa and various weed hosts (Lenne and Sonoda, 1978a,b). Since the patho-gen infects most of the leguminous hosts besides a wide array of urdbean germplasm, studies on its patho-genic variability were under-taken. MATERIALS AND METHODS Infected leaf samples of urdbean were collected from different crop growing areas ofHimachal Pradesh. Eleven isolates representing all urdbean growing dis-tricts of the state were collected and named as C'I '