An official website of the United States government.
Thrips-vectored Tomato spotted wilt virus (TSWV) is one of the major pests of fresh tomato and pepper in the Southeast. TSWV is transmitted in the Southeast primarily by tobacco thrips and western flower thrips. Management of TSWV in tomato and pepper is difficult and requires the use of multiple preventive tactics, including TSWV-resistant plant cultivars, reflective mulch, chemical treatments, and weed management which should be based on a pre-season assessment of risk. <P>The goal of this project is to develop a reduced-risk management system for thrips and TSWV in tomato and pepper in the Southeast. The objectives are to: 1) optimize use of available TSWV management options and define their effectiveness, costs and benefits when used alone and in combination, 2) refine and extend weather-based models for predicting the risk of TSWV spread into crops in spring, 3) develop a risk-based decision guide for growers to evaluate the need for and the optimum combination of TSWV management tactics, and 4) facilitate implementation of reduced risk thrips and TSWV management in tomato and pepper through extensive out-reach programs. <P>Major milestones are to set up all research and extension activities during fall 2008, plan meeting at the SE Regional Fruit & Vegetable Conference (SEFVC), analyze preliminary data and continue to develop and refine the thrips/ TSWV risk prediction model developed in NC on the project webpage. Also a preliminary survey of TSWV management practices used by growers in GA, FL, NC, and SC will be conducted. Beginning January 2009 we will meet annually at the SEFVC to report results and coordinate small plot experiments and extension effort for the coming year. We will present TSWV management information at the IX International Symposium on Thysanoptera and Tospovirus at Sidney, Australia, Sept. 2009 and publish results. We will also refine the thrips/TSWV risk prediction model for the TSWV Risk Assessment and Dynamic Decision Support Tool which will be posted on an expanded thrips /TSWV website with current management information (www.tomatospottedwiltinfo.org). We will also produce and distribute TSWV management bulletins with risk assessments by State, present TSWV management information at the SEFVC, national and regional entomology, pathology and horticulture meetings, finalize surveys, and publish results.<P> Output metrics will include the number of presentations at professional meetings, refereed journal articles, research reports and non-refereed research reports as well as the number of extension bulletins or other extension publications, the number of participants at thrips-vectored Tospovirus meetings and workshops, the number of participants in the email notification of TSWV risk in the field, the number of responses to annual surveys that indicate adoption of a TSWV risk mitigation tactics as a result of the outreach effort in this project, and the annual stakeholder panel assessment.
Non-Technical Summary: Thrips-vectored Tomato spotted wilt virus (TSWV) is a major virus problem of crops in the Southeast, causing as much as $100 million in damage annually. Two important crops at-risk from TSWV are fresh tomato and pepper. Production of these crops in FL, GA, NC, and SC represents 54% of the US annual production and the majority of acreage that is affected by TSWV. TSWV is transmitted in the Southeast primarily by the small insects known as tobacco thrips and western flower thrips. Management of TSWV in tomato and pepper is difficult and involves the use of many preventive controls, including TSWV-resistant plants, reflective ground cover, chemical treatments, and weed management. No single practice provides 100% control and all must be applied prior to or early during disease spread to be effective. Thus, an integrated management approach based on a pre-season assessment of risk is needed. The goal of this project is to develop a reduced-risk management system for thrips and TSWV in tomato and pepper in the Southeast. The objectives are to: 1) Optimize use of available TSWV management options and define their effectiveness, costs and benefits when used alone and in combination. 2) Refine and extend weather-based models for predicting the risk of TSWV spread into crops in spring. 3) Develop a risk based decision guide for growers to evaluate the need for and the optimum combination of TSWV management practices. 4) Facilitate implementation of reduced risk thrips and TSWV management in tomato and pepper through extensive out-reach programs. The impact of such a management system will be to reduce or eliminate millions of dollars in annual losses from tomato and pepper crop failures in the Southeast due to TSWV. This will also stabilize production of these two important vegetable crops and at the same time reduce pesticide inputs to these fresh vegetables.<P> Approach: (Objective 1) We will optimize procedures for using available TSWV management options and define their effectiveness, costs and benefits when used alone and in combination. Previous research has demonstrated the effectiveness of resistant cultivars, UV-reflective mulch, Actigard, and other chemical treatments in reducing TSWV incidence and has shown that their effects can be additive, dependent on disease pressure. In the on-farm trials, separate experiments will be conducted on early and mid-season spring and fall plantings of tomato and on early and late-planted spring pepper. (Objective 2) We will refine and extend weather-based models for predicting the relative favorability of conditions for spread of TSWV spread into crops in spring. The risk-based TSWV management decision aid for growers will be based on 1) the abundance of TSWV-infected winter weeds that serve as sources of TSWV, 2) the final incidence of TSWV in a susceptible crop as related to the timing and magnitude of Frankliniella fusca from winter hosts into the crop in spring, and 3) winter and spring temperatures and rainfall during critical periods as determinants of thrips vector population growth and dispersal. We will apply knowledge of these relationships to characterize the suitability of conditions for spread of TSWV into tomato and pepper crops during spring in the production areas of NC and SC and develop and refine new models for GA and FL. (Objective 3) We will develop a risk based decision guide for growers to evaluate the need for and the optimum combination of TSWV management tactics for their situation. This guide will be developed to aid growers in assessing their need to implement specific TSWV management tactics or combinations of tactics. The system will be web-based so that the grower can enter the crop, the anticipated planting date, a zip code to link to weather data, and the historic incidence of TSWV in the crop in that field. The points associated with the assigned exposure levels for the site will then be used to predict a TSWV exposure score. Each management option will be assigned a TSWV reduction factor and these values will then be used to calculate the effect of the management option or a combination of options on the base TSWV exposure score. A comparison of the costs/benefits of various management options will be provided to determine which system provides maximum benefit to the growers. (Objective 4) We will facilitate implementation of reduced risk thrips and TSWV management in tomato and pepper through extensive out-reach. This objective will be accomplished by: 1) on-farm demonstrations of specific management tactics and the effect of host plant resistance, 2) field days and extension grower meetings in each State, 3) TSWV/thrips management outreach in conjunction with field days 4) newsletters submitted to trade publications such as Southeast Farm Press, Georgia Fruit and Vegetable Grower Newsletter, 5) information posted on the project website, and 6) postings of current risk factors by State.