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Abstract
Anthracnose of pepper incited by Colletotrichum spp. causes severe losses in Capsicum spp. due to pre- and postharvest fruit decay. Four Colletotrichum species (C. gloeosporioides, C. capsici, C. acutatum, and C. coccodes) have been identified as causal agents of pepper anthracnose in Louisiana. The major incitants are C. gloeosporioides and C. capsici. Potential sources of inoculum in cayenne pepper were evaluated in field studies uding various combinations of `clean seed`, `infected seed`, `clean field`, and `infested field` treatments. Throughout the two seasons the clean seed-clean field combination averaged 9% infected pods, whereas the use of infected seed or planting in an infested field resulted in 66% and 62% infected pods, respectively. Detached mature red bell pepper and tomato fruits were inoculated with 22 Colletotrichum isolates from pepper and tomato representing C. gloeosporioides, C. capsici, C. acutatum, and C. coccodes. The fruits were inoculated with a conidial suspension (25 ul, 1.0E6 conidia/ml) and were incubated at 24 C for nine days after which the percentage of fruits showing lesion development was recorded and lesion diameters were measured. All isolates, regardless of their original host, caused characteristic anthracnose symptoms on fruit of both hosts. Field applications of chlorothalonil (Bravo 500 at 3.8 ml/liter) and maneb (manex 4F at 1.9 ml/liter) were made to cayenne and bell pepper to determine the efficacy of these fungicides for the control of anthracnose. Spray applications were made to the point of runoff at time intervals ranging from one to four weeks. A significant reduction in the incidence of pod infections was obtained with both fungicides applied at one- and two-week intervals. unsprayed check treatments, while only 25% and 37% of the pods were diseased in the weekly sprayed chlorothalonil and maneb treatments, respectively. [AS]