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Comparison of disease progress curves for yam anthracnose (Colletotrichum gloeosporioides)

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Health & Diseases
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Biological & environmental
Kenward, M.; Simons, S.A.; Sweetmore, A.

The incidence and severity of foliar anthracnose, caused by Colletotrichum gloeosporioides, were recorded for seven fields of yams (Dioscorea alata var. White Lisbon) in Barbados over a complete growing season. A scoring system was developed to estimate severity, placing the emphasis on the earliest, least visible stages of the disease. Disease progress curves were described in terms of the logistic model and the effects of site and leaf age on the parameters as well as on disease at tuber bulking were analysed. Differences between sites indicated that disease was more severe in areas of higher rainfall. In severe epidemics, disease predominated on young leaves. Fungicides applied sufficiently early can delay the onset of disease and slow the rate of disease progress.