COMPARISON OF DISEASE PROGRESS CURVES FOR YAM ANTHRACNOSE (COLLETOTRICHUM-GLOEOSPORIOIDES)

The incidence and severity of foliar anthracnose, caused by Colletotri chum gloeosporioides, were recorded for seven fields of yams (Dioscore a alata var. White Lisbon) in Barbados over a complete growing season. A scoring system was developed to estimate severity, placing the emph asis on the earliest, least visible stages of the disease. Disease pro gress curves were described in terms of the logistic model and the eff ects of site and leaf age on the parameters as well as on disease at t uber bulking were analysed. Differences between sites indicated that d isease was more severe in areas of higher rainfall. In severe epidemic s, disease predominated on young leaves. Fungicides applied sufficient ly early can delay the onset of disease and slow the rate of disease p rogress.