Study on disease of riperot of chilli fruits caused by colletotrichum capsici sydy butter and bisby

Abstract

1. Collection of samples of infected capsicum fruits was made from three districts of assam viz. Kamrup, Nowgong and Darrang in the year 1978. 2. (a) 12 fungal genera was isolated from 10 varieties of chilli (collected) and the genus Colletotrichum was found to be responsible for red-ripe infection. 3. (b) 100 isolates were obtained from chilli fruits tissues infected by Colletotrichum capsici (Syd.) Butler and Bisby. Only 5 Strains (AS, BS, CS, DS and ES.) were distinguished from among them as effective pathogens. The degree of pathogenicity of 5 Strains had been studied and their different degrees of pathogenicity was determi-ned. only 3 Strains (AS, BS and CS.) were found to be virulent. (c) Test for chilli was carried out with 12 varieties of capsicum fruits of which variety clustard was found to be very susceptible and variety Rukuni proved to be highly resistant type to the infection of Colletotrichum capsici. 3. Study on fungal physiology of the virulent Strains showed variations in growth characters in different nutrients and host extract media. Eviden-ces also showed that external stimuli viz. Tempera-ture, relative humidity and light and darkness had much influence on growth and sporulation of these Strains of Colletotrichum capsici. 4. 12 different varienties of chilli were cultivated in the field to carry out certain experimental observa-tions. The spread of the disease was accomplished by air-borne spores during ripening of the chilli fruits in the fields. Latent infections of the fruits were mainly responsible for carrying over of the disease in seeds. 5. Presence of Colletotrichum capsici was recorded in both rhizosphere and non-rhizosphere soils of chilli field. Rhizosphere soil of susceptible chilli variety contributed higher percentage of Colletotrichum capsici than the rhizosphere soils of resistant and Moderately resistant chilli varieties.