Files
Abstract
Whitefly-transmitted viruses are a major production concern for fall-grown vegetables including squash, tomatoes, and beans in the southeastern United States. Currently, no single pest management tactic has proven to provide sufficient control of whitefly-transmitted viruses. To aide in the development of appropriate pest management programs, the spatial distribution and temporal patterns of whitefly transmitted viruses were documented. In squash, symptoms of disease caused by the whitefly-transmitted virus complex (WTVC) were initially randomly distributed but later shifted to an aggregated pattern as the incidence of virus-infected plants increased over time. Mapping of interpolated cluster indices from SADIE analysis revealed an edge effect on the spread of WTVC infection over space and time in squash fields. Similar patterns were observed on snap beans where the incidence of sida golden mosaic virus (SiGMV) was greater along edges in snap bean fields. The presence of SiGMV infected prickly sida in field margins adjacent to snap bean plots was associated with earlier occurrence and higher SiGMV incidences in snap beans. Multiple field trials were conducted to assess different planting dates, mulch types, row cover, planting materials, and types of squash as tactics for managing WTVC in squash. Using data generated from these field trials, a risk assessment index for WTVC in squash was developed through a novel approach. Random forest analysis was used to determine the quantitative importance of different variables as predictors of WTVC. The risk index was validated through survey of commercial squash fields where the calculated risk point values showed a positive linear relationship with the observed WTVC incidences. The risk index developed through this study may be used as a guide to determine suitable integrated pest management programs that would help mitigate high levels of WTVC and yield losses in squash fields.