Biology and Control of Pepper Anthracnose

Anthracnose (caused by Colletotrichum capsici or C. gloeosporioides) of bell peppers (Capsicum annum) has become a serious problem in recent years on the Eastern Shore of Virginia. The purpose of this research was to characterize isolates of the fungus from the Eastern United States, to compare them with the type species from the American Type Culture Collection, and to evaluate fungicides for disease management. Two cultivars of pepper were inoculated with a conidial suspension, and held in a dew chamber. Lesions were counted and measured every 48 hours. The type species was either not pathogenic or only mildly virulent; most of the virulent isolates originated in areas of intensive pepper production. In addition to pathogenicity experiments and traditional morphology, the Biolog® system was used to compare the ability of fungi to utilize different carbohydrate combinations in 96-well plates. Plates were read at 96 and 168 hours. Analysis of data, by Ward's statistical method, could reliably distinguish field isolates if based on 15 or more replications, but species-level identification was inconsistent. Standard fungicides and new compounds were compared in a field test with four replications of treatments in a randomized complete block design. Fruits were harvested three times, weighed for yield, and the number of marketable and diseased fruit recorded. Aggressive isolates from green pepper were controlled by applications of maneb, or alternation of maneb and strobilurin fungicides.