Chandra Mohanan, R.Kaveriappa, K.M.2014-08-192014-08-1920079th International cocoa research conference p 323-326http://hdl.handle.net/123456789/4852Colletotrichum disease of cocoa (Theobroma cacao L.) occurs in most of the cocoa growing regions in India. Symptomatology of the disease reveals that besides pod rot there are three kinds of foliar symptoms, viz., blight, shot hole and irregular spot. The leaves, pods and seedlings showing various symptoms of the disease were collected from 101 cocoa gardens including nurseries in the states of Kerala, Karnataka and Tamil Nadu. Isolation of the pathogen from infected plant parts invariably yielded Colletotrichum gloeosporioides Penz. A total of 312 isolates of the pathogen were collected, of which 198 were from leaves, 82 from pods, and 32 from seedlings. Based on the colour of the colony when grown on potato dextrose agar medium the isolates under each symptom group were classified into light (gray), dark (olive gray to black) and white types. Disease index was calculated by inoculating 18-day-old cocoa seedlings. Of the 312 isolates, 299 were pathogenic, of which 210 incited blight, 77 incited shot hole and only 12 isolates incited irregular spot. The most virulent isolate among blight, shot hole and irregular spot group was found in Kanyakumari, Cannanore and Chikmagalur districts respectively. The study further showed that most of the isolates of C. gloeosporioides were pathogenic and among them leaf blight group of isolates were predominant and wide-spread. Inoculation trials also revealed a great variation in pathogenicity among the isolates under each symptom group. In general isolates of light type were found to be most virulent. From the results it may be concluded that while screening for disease resistance it is desirable to select light type of isolates covering a wide range of collections.enArticle