Effect of Temperature and Wetness Duration on Anthracnose Fruit Rot Development on Different Strawberry Cultivars
B. B. FORCELINI (1), N. Peres (2). (1) University of Florida, Wimauma, FL, U.S.A.; (2) University of Florida, Gulf Coast Research and Education Center, Wimauma, FL, U.S.A.
Florida is the largest producer of winter strawberries in the world. Anthracnose Fruit Rot (AFR), caused by <i>Colletotrichum acutatum</i>, can greatly affect production if not controlled. The use of fungicides in addition to cultural practices such as the use of less susceptible cultivars are important tools for AFR control. In addition, disease forecasting models for AFR based on temperature and Wetness Duration (WD) have been developed to time and reduce fungicide applications on strawberry. The objective was to evaluate the effects of temperature and WD on the development of AFR on strawberry cultivars with different levels of susceptibility to the disease. Immature strawberry fruit of the cultivars Camarosa (highly susceptible) and Strawberry Festival (moderately susceptible) were inoculated with a 106 conidia/ml suspension and incubated under wetness periods ranging from 0.5 to 48 hours and temperatures 15, 20 and 25°C. Fruit were then dried and moved to 25°C for nine days and then evaluated for disease incidence. Disease incidence increased non-linearly with increasing temperature and WD for both cultivars and disease development curves at 15, 20, and 25°C and from 0 to 48 h of WD were similar. Disease symptoms start to develop on both cultivars at 15°C and with 3 hours of WD. Optimum temperature and wetness duration for both cultivars were 20°C and 48 hours, respectively. However, overall disease incidence was higher for ‘Camarosa’ than for ‘Strawberry Festival’.
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