Spatial and temporal physiognomies of whitefly and tomato yellow leaf curl virus epidemics in southwestern Florida tomato fields

Authors: ANCO, DAN - Clemson University; ROUSE, LISA - Washington Department Of Agriculture; LUCAS, LEON - Glades Crop Care; PARKS, FELICIA - Glades Crop Care; MELLINGER, CHARLES - Glades Crop Care; Adkins, Scott; Kousik, Chandrasekar - Shaker; ROBERTS, PAM - University Of Florida; STANSLY, PHIL - University Of Florida; HA, MIAE - Argonne National Laboratory; Turechek, William

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/26/2019
Publication Date: 11/20/2019
Citation: Anco, D., Rouse, L., Lucas, L., Parks, F., Mellinger, C., Adkins, S.T., Kousik, C.S., Roberts, P., Stansly, P., Ha, M., Turechek, W. 2019. Spatial and temporal physiognomies of whitefly and tomato yellow leaf curl virus epidemics in southwestern Florida tomato fields. Phytopathology. 110(1):130-145. https://doi.org/10.1094/PHYTO-05-19-0183-FI.
DOI: https://doi.org/10.1094/PHYTO-05-19-0183-FI

Interpretive Summary: Epidemics of tomato yellow leaf curl virus have been problematic to tomato production in the southeastern United States since its first detection in Florida in the late 1990s. Current strategies for management have had limited success for controlling either the whitefly or TYLCV. Areawide pest management (AWPM) – loosely defined as a coordinated effort to implement management strategies on a regional scale – may be a viable alternative. The objective of this study was to characterize the populations of whitefly and TYLCV in commercial tomato production in southwest Florida and utilize this information as a means to predict whitefly density and TYLCV disease incidence as a function of environmental and geographical factors. Scouting reports and daily weather data were collected from cooperating growers located across ~20,000 acres in southwest Florida from 2006-2012. Analyses showed that the incidence of TYLCV increased proportionally with mean whitefly density as the season progressed, that populations of whiteflies and TYLCV were similar in 2 km radius, and that weather was better at predicting whitefly density than at predicting TYLCV incidence. Results of this study helped to identify the extent at which populations of whitefly and TYLCV exist over the agricultural landscape of southwest Florida, and the environmental conditions that favor epidemic growth. This information can be used to delineate the treatment area in an AWPM program and for timing control measures for managing TYLCV epidemics.

Technical Abstract: Epidemics of tomato yellow leaf curl virus (TYLCV; species Tomato yellow leaf curl begomovirus) have been problematic to tomato production in the southeastern United States since its first detection in Florida in the late 1990s. Current strategies for management focus on farm-centric tactics that rely mainly on the strategic application of insecticides for whitefly vector control, the use of TYLCV-resistant cultivars, roguing infected plants, and various cultural controls. With the exception of the use of resistant varieties, these approaches have had limited success for controlling either the whitefly or TYLCV. Unfortunately, not all horticulturally desirable cultivars have resistance to TYLCV, thus alternative management strategies are needed. Areawide pest management (AWPM) – loosely defined as a coordinated effort to implement management strategies on a regional scale – may be a viable alternative. For an AWPM program to be successful, the spatial and temporal dynamics of the targeted pathogen and pest populations must be defined. The objective of this study was to characterize the populations of whitefly and TYLCV in commercial tomato production in southwest Florida and utilize this information as a means to predict whitefly density and TYLCV disease incidence as a function of environmental and geographical factors. Scouting reports were submitted by cooperating growers located across ~20,000 acres in southwest Florida from 2006-2012. Daily weather data was obtained from several local weather stations. Moran’s I was used to assess spatial relationships and polynomial distributed lag regression was used to determine the relationship between weather variables, whitefly, and TYLCV. Analyses showed that the incidence of TYLCV increased proportionally with mean whitefly density as the season progressed. Nearest neighbor analyses showed a strong linear relationship between the logarithms of whitefly densities in neighboring fields. A similar relationship was found with TYLCV incidences. Correlograms based on Moran’s I showed that both of these relationships extended beyond neighboring fields and out to approximately 2 km, and that values of I were generally higher during the latter half of the production season. Weather was better at predicting whitefly density than at predicting TYLCV incidence. Whitefly density was best predicted by the number of days with an average temperature between 16 and 24 °C (T16to24) and relative humidity (RH) over the previous 31 days and vapor pressure deficit over the last 8 days. TYLCV incidence was best predicted by T16to24, RH, and maximum wind speed over the previous 31 days. Results of this study helped to identify the extent at which populations of whitefly and TYLCV exist over the agricultural landscape of southwest Florida, and the environmental conditions that favor epidemic growth. This information can be used to delineate the treatment area in an AWPM program and for timing control measures for managing TYLCV epidemics.