Tiny pest, big problem: Auburn researchers take on tomato virus outbreak

When carefully inspecting produce, many consumers look for physical imperfections like blemishes, bruises or other visible damage. Meanwhile, horticultural researchers focus on what shoppers can’t see — pests beneath the surface that pack a serious punch: thrips.

In 2020, a major outbreak of tomato spotted wilt virus — a thrips transmitted virus — was reported in the Chandler Mountain region of northeast Alabama. Since much of the state’s tomato production is in that region, Auburn researchers moved quickly to study the spread.

Paulo Gimenez Cremonez, an assistant professor of entomology and plant pathology, focuses his research on fruit and vegetable production and integrated pest management. His research through the Alabama Agricultural Experiment Station centers heavily on thrips pressure in tomatoes.

“There have been occasional outbreaks of this virus over the last few years, but planting resistant varieties is currently our best response, along with strategic management,” Cremonez said.

Tomato spotted wilt virus is neither a fungus nor a bacterium, but 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.

Seeing the need for action, Cremonez proposed a specialty crop research project with the U.S. Department of Agriculture. This multi-state project takes research and Extension outreach to help growers in Alabama and the Southeast manage outbreaks and reduce the risk of future spread.

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, effectively disrupting production.

These outbreaks resulted in major losses for Alabama tomato producers over the last two growing seasons. In response, Auburn researchers and Alabama Extension Specialists have plans of action to manage this pesky pest.

Cremonez said the first line of defense that he encourages tomato growers to utilize is an active monitoring scouting plan.

“Preventative management is vital, and 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,” he said.

For early detection, growers can incorporate blue sticky traps to catch early movement. It also helps them time their insecticide applications and identify the hot spots within their 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 so important.

Even though “tomato” is in the name, tomatoes are not the only fruits and vegetables vulnerable to tomato spotted wilt virus. Eggplant, lettuce, peanuts, peppers and potatoes are all susceptible to the virus. 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.”

 Cremonez is not limiting this project to the state. He said hopes that this project 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 s 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.

Whether in commercial fields or backyard gardens, growers can rely on Auburn research and Alabama Extension for support as they grow Alabama’s fresh, locally produced crops.