First Report on Association of Colletotrichum coccodes with Chili Anthracnose in India

Chili (Capsicum annuum L.) is an important condiment and cash crop grown throughout India, including Andhra Pradesh, Karnataka, Maharashtra, Punjab, Tamilnadu, and Himachal Pradesh. In Himachal Pradesh (HP), a northwestern Himalayan state of India, chilies including sweet pepper occupy an area of 2,447 ha with total production of approximately 31,810 t and productivity of 13.00 t per hectare. In 2007 and 2008, chili- and sweet pepper-growing areas of HP were surveyed for the prevalence of fruit rot/anthracnose disease caused by a complex of Colletotrichum species. Fields infested with disease were randomly sampled and four samples from each location were collected. Disease incidence ranged from 12.5 to 45.0% based on total plants assessed in the field. Symptoms of disease in the field included light brown, sunken lesions containing salmon-colored masses of conidia and microsclerotia on the fruit. Microscopic examination of the diseased samples revealed a variation in morphology of spores from two isolates (Cc 70 and Cc 74) collected from two locations in HP, the Kotkhai area of district Shimla and Shamsher (Ani) locality of district Kullu. Five fruits and ten leaves from five plants of a susceptible local variety were inoculated with a suspension of 5 × 10⁵ conidia/ml of isolates Cc70 and Cc74 using a pin prick method as described by Montri et al. (2). The inoculated fruits and leaves were kept in humid chambers at 25 ± 1°C with 12 h of light. After 48 h, the fruits and leaves were observed daily for the appearance of disease symptoms. Disease symptoms were similar to those of natural infections but with darker lesions. The fungus was recovered from infected fruit on Mathur's medium (glucose 2.80 g, peptone 2.00 g, magnesium sulfate hydrated 1.72 g, potassium dihydrogen orthophosphate 1.23 g, and agar 1.50 g/liter) and initially produced white-to-gray mycelia that became dark brown with age. Setae were present along with production of microsclerotia by the tenth day of culturing. A daily average growth of 8.1 mm was recorded on potato dextrose agar at 25 ± 1°C. Conidia were hyaline, unicellular, aseptate, and fusiform abruptly tapering to each end, and 15.5 to 19.6 μm long and 4.2 to 5.3 μm wide. The fungus was identified as Colletotrichum coccodes based on morphological and cultural traits as per the descriptions of Junior et al. (1). The identity of the isolates was confirmed by amplifying the internal transcribed spacer (ITS) region using primer pair ITS1 and ITS4 (3). The sequences (550 bp) were subjected to a BLAST search with the isolates showing the highest identity to GenBank Accession Nos. GU935878 and EF017205. The sequences have been submitted to GenBank (Accession Nos. HQ264175 and HQ264176). Very few reports exist about the natural occurrence of C. coccodes on Capsicum spp. around the world. To our knowledge, this current report constitutes the first record of this pathogen on Capsicum spp. from the Indian subcontinent. References: (1). H. J. T. Junior et al. Summa Phytopathol. Botucatu 33:418, 2007. (2). P Montri et al. Plant Dis. 93:17, 2009. (3) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990.