Tiny pest, big problem: Researchers take on tomato virus outbreak
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By Kacey Watson
Alabama Extension News
When carefully inspecting produce, many consumers look for visible, physical imperfections like blemishes or bruises.
Meanwhile, out in the fields, horticultural researchers focus on issues shoppers cannot see, like thrips. These pests get beneath the surface of produce while it is growing and pack a serious punch.
In 2020, a major outbreak of tomato spotted wilt virus – a thrips transmitted virus – was reported in the Chandler Mountain region of northeast Alabama. That region produces a large percentage of Alabama’s tomatoes, so employees of Alabama Cooperative Extension System and Auburn moved quickly to study the spread.
Paulo Gimenez Cremonez is a specialist with Alabama Extension at Auburn University and an assistant professor of entomology and plant pathology with the Auburn College of Agriculture. His research focuses on fruit and vegetable production and integrated pest management. With his work through the Alabama Agricultural Experiment Station, Cremonez is tackling thrips pressure in tomatoes.
“There have been occasional outbreaks of this virus over the last few years,” Cremonez said. “Planting resistant varieties is currently our best response, along with strategic management.”
A Closer Look
Tomato spotted wilt virus is not a fungus or bacterium. Instead, it is a virus that infects hundreds of plant species. The virus is mainly spread by western flower thrips, among other thrips species, which are barely visible to the naked eye. Thrips act as vectors by picking up the virus and transmitting it to uninfected plants. Once acquiring the virus in their larval stage, the thrips carry and spread it for the rest of their lives.
According to the U.S. Department of Agriculture, 64% of Alabama’s tomato production is within St. Clair and Blount counties. From 2020 to 2025, there have been three major outbreaks of tomato spotted wilt virus in the state, effectively disrupting production. These outbreaks resulted in major losses for Alabama tomato producers over the last two growing seasons.
Seeing the need for action, Cremonez proposed a specialty crop research project with the U.S. Department of Agriculture. This multi-state project uses research and Extension outreach to help growers in Alabama and the Southeast manage outbreaks and reduce the risk of future spread. Cremonez said an active monitoring and scouting plan is the first line of defense against thrips.
“Preventative management is vital,” Cremonez said. “The tools in our toolbox – biological and cultural control, incorporation of reflective mulch, surveying, resistant varieties, trapping and weed control – all help growers protect their tomatoes.”
Mapping Detection
For early detection, growers can incorporate blue sticky traps to catch early movement. This also helps with timing insecticide applications and identifying hot spots in fields. Tomato spotted wilt virus symptoms emerge after infection, but thrips usually show up on sticky traps before symptoms become obvious.
Early signs of damage include stunted growth, bronzing, ring spots, necrosis and deformed fruit – indicators that a biological culprit may be at work. By the time these symptoms appear, the issue is already established, which is why early scouting and trapping is important.
Even though tomato is in the name, other fruits and vegetables are vulnerable to tomato spotted wilt virus. Eggplant, lettuce, peanuts, peppers and potatoes are all susceptible. Even some ornamentals, like impatiens and begonias, act as hosts and spread the virus.
While this virus is concerning because of its longevity and spread, researchers are using management tactics to help mitigate its impact. From rotation to insecticides, the team is trying a variety of methods to analyze outcomes.
“We’re seeing moderate-to-high efficacy with one of the newest chemistries, Incipio from Syngenta. It has a long residual and, so far, has performed very well on thrips, whiteflies and even caterpillars,” Cremonez said. “We’ll keep testing both old and new insecticides to find what’s most beneficial and cost-effective for our growers. New options also allow for better rotation schemes, which are important for managing insecticide resistance.”
Expanding Efforts Regionally
Cremonez is not limiting this project to the state. He said he hopes that this research will provide guidance to growers across the Southeast.
“Currently, the Southeast does not have a coordinated stakeholder-driven roadmap for addressing this problem across states,” he said. “Growers need better information on how resistance-breaking affects production, which management gaps are most urgent and what tools are needed to support decisions.”
With this initiative, Cremonez and collaborators will provide research and Extension outputs including advisory board discussions, Extension events, grower visits, listening sessions, needs assessments, online communication, regional meetings and scouting guides and surveys.
To share practical advice on scouting and monitoring, Cremonez created a video about thrips and tomato spotted wilt virus. It is available on Alabama Extension’s YouTube channel at YouTube.com/@AlabamaExtension.
Trade and brand names used in this article are given for information purposes only. No guarantee, endorsement. or discrimination among comparable products is intended or implied by the Alabama Cooperative Extension System.
