Characterization and pathogenicity of colletotrichum species causing anthracnose in chilli

Abstract:

Chilli anthracnose, once thought to be caused by a single Colletotrichum species, is now known to involve a species complex whose members differ in virulence, host preference, and fungicide sensitivity. This research characterized 64 Colletotrichum isolates recovered from anthracnose-affected chilli fruits collected across Gujarat and Tamil Nadu during 2022-2023. Morphological examination and multi-locus phylogenetic analysis (ITS, TUB2, ACT, GAPDH) identified four species: C. truncatum (43.8%), C. gloeosporioides (28.1%), C. siamense (18.8%), and C. fructicola (9.4%). Pathogenicity tests on detached chilli fruits (cv. Pusa Jwala) showed that C. truncatum was the most aggressive, producing the highest disease severity (7.8 on 0-9 scale) and incidence (84.6%). Conidial morphology, colony characteristics, and growth rates differed significantly among species. These findings confirm a multi-species etiology for chilli anthracnose in India and highlight C. truncatum as the dominant and most virulent pathogen, which has direct implications for fungicide selection and resistance breeding strategies.