Location: Subtropical Plant Pathology Research2009 Annual Report
1a. Objectives (from AD-416)
To determine and characterize factors associated with the dispersal and development of the whitefly-transmitted viral disease watermelon vine decline, as well as two emerging viral diseases cucurbit leaf crumple and cucurbit yellow stunting disorder, and develop a regional decision support system for managing them.
1b. Approach (from AD-416)
Perform intensive field surveys of commercial cucurbit, tomato, and other vegetable crops in southwest Florida to characterize the temporal and spatial pattern of whiteflies, and identify reservoirs of Squash vein yellowing virus, Cucurbit leaf crumple virus, and Cucurbit yellow stunting disorder virus. Use the spatial information to identify factors that contribute to their increase and determine how they may impact management. Develop the tools necessary to delivery real-time forecasts (decision support system) of virus incidence and whitefly density to the industry. Improve understanding of whitefly transmission of SqVYV by examining the interaction of plant age, time of infection, and virus distribution, and whitefly acquisition and transmission of SqVYV. Specialty Crops Research Initiative.
3. Progress Report
This project is related to objective 1 of the inhouse project: Characterize ecology, biology, epidemiology, genetics and host interactions of domestic, exotic, newly emergent, and re-emerging pathogens. The intent of this study is to develop strategies for managing Squash vein yellowing virus (SqVYV)-induced watermelon vine decline and diseases caused by other whitefly-transmitted viruses of important vegetable crops in Florida and the Southeast. This will be accomplished by: 1) Developing cultural and chemical controls that focus on environmentally safe and cost-effective management strategies in production fields; 2) Characterizing the acquisition and transmission process of SqVYV in single and mixed infections with Cucurbit leaf crumple virus, Papaya ringspot virus, and Cucurbit yellow stunting disorder virus in watermelon; 3) Characterizing spatial and temporal patterns of viral epidemics and whitefly densities in production fields and in neighboring fallow fields, irrigation ditches, and hedgerows to gain an understanding of epidemic dynamics and identify “hot spots” and reservoir crops for both whitefly and viruses; and 4) Developing a decision support system using the information obtained above to deliver recommendations for managing whiteflies and virus. This report addresses the progress of (3) and (4). A 2.5 acre watermelon field was planted at the University of Florida’s Southwest Research and Education Center in Immokalee, FL to allow us to monitor and characterize the spatial and temporal characteristics of viral epidemics and whitefly populations in a setting where whitefly populations are left unmanaged. The field was scouted and whitefly and aphid counts were gathered weekly beginning 1 week after planting until harvest. In addition, environmental data was collected using the Florida Automated Weather Network. Despite the abundance of whiteflies, particularly toward the end of the season, no SqVYV or other whitefly-transmitted viruses were detected in this field. This was in line with what was observed in all of southwest Florida watermelon production, and the absence of significant disease is believed to have been related to the two hard freezes experienced across the region just prior to planting. We will replant the field in October and repeat the procedure as described; future plantings are also planned. We continue to receive weekly scouting reports of whitely densities and virus incidence in commercially produced tomato, watermelon, and potato crops from our collaborators in southwest Florida. The data is entered into the GIS program ArcView which permits us to map and view the data at any given time and location of our choosing. We are in the process of analyzing the data to determine factors that contribute to viral epidemics on a regional scale, but the analysis generally requires several years of data to sufficiently identify trends which have yet to collect. We have just hired an individual with a strong background in GIS to assist in the manipulation and analysis of the data, and we have also just hired a third-party provide to develop the web-based infrastructure for the decision support system.