2010 Annual Report
Whitefly-transmitted SqVYV and CuLCrV have had serious impact on watermelon production in southwest and west-central Florida in the past 5 years. A field study was designed to characterize the spatial and temporal patterns of disease, quantify viral associations, and determine how environmental factors affect epidemic development. The study was conducted over six growing seasons in a 1 ha field of ‘Fiesta’ in Immokalee, FL. It was observed that not all viruses appeared in every growing season, and that certain environmental parameters may be useful in predicting the occurrence of SqVYV. Data also suggest that SqVYV and CuLCrV are being introduced by separate whiteflies, even thought the whiteflies could emigrate from the same field. The data gathered from this study can be used to partially predict epidemic development and test management strategies that ultimately result in better control. Tomato yellow leaf curl virus (TYLCV) has caused millions of dollars of lost production. In collaboration with growers we collected and analyzed insect and disease scouting reports and used regional weather data to determine spatial and temporal features associated with TYLCV epidemics and whitefly densities. The data show that the severity of TYLCV closely follows the increase in mean whitefly density, and that the average numbers of whiteflies in any one field is linearly related to the number of whiteflies in its neighboring fields. There is a positive correlation between wind speed and whitefly density and higher temperatures have a negative impact on both whitefly density and TYLCV. Wintertime minimum temperatures have an impact on both whitefly populations and virus incidence. The results of the analyses argue for a greater regional effort in managing whiteflies and TYLCV and we are developing a decision support system for management and tracking whiteflies and virus across commodities to help achieve this goal.