Technical Abstract: Whitefly-transmitted Squash vein yellowing virus (SqVYV), Cucurbit leaf crumple virus (CuLCrV), Cucurbit yellow stunting disorder virus (CYSDV) and aphid-transmitted Papaya ringspot virus type W (PRSV-W) have had serious impact on watermelon production in southwest and west-central Florida in the past 5 years. The epidemiology of these viruses is poorly understood. We designed a field study to characterize the spatial and temporal patterns of disease, quantify viral associations, and determine how environmental factors affect epidemic development over five growing seasons in a 2.5 acre field of ‘Fiesta’ at the University of Florida Southwest Florida Research and Education Center (SWFREC) 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. The data also indicated the level of association between SqVYV and CuLCrV was not greater than what would be expected from random associations, indicating that disease may be being introduced by separate whiteflies, although the whiteflies may be emigrating from the same source watermelon field. The data gathered from this study along with parameters characterizing acquisition and transmission can be used to predict epidemic development (e.g., development of forecasters), and test management strategies that ultimately result in more efficient control strategies.