The dreaded disease tomato spotted wilt virus (TSWV) and its effect on tomato production is the focus of a multi-state research effort that includes a predictive model developed at North Carolina State University.

“They’re looking at being able to predict the severity or the potential of TSWV — that’s a big part of this overall project,” says Stormy Sparks, University of Georgia Extension entomologist. “If we can learn to predict if it’s going to be a mild or severe year, we have a better idea of what inputs to put into a crop.”

The research also is looking at resistant tomato varieties, says Sparks. “We’ve got about 10 varieties we’re looking at in Camilla at the Stripling Irrigation Research Park and others at Tifton and Ridgeville. In vegetables and tomatoes, resistant varieties are by far to best way to manage tomato spotted wilt virus. The problem is that we’re looking at about 30 varieties of tomatoes in Tifton, and almost all of them have one source of genetics,” he says.

Resistant varieties definitely are the preferred method for managing the virus, he adds. “The problem is that when we lose that source of resistance, we lose all 30 varieties at once. History tells us that when it changes, it changes dramatically. We’ll lose it all at once, and then we’re back to trying to manage it with other techniques,” says Sparks.

One of the methods for controlling the virus is the use of plastic mulch, he says. The standard for the industry in spring production is black plastic. It warms the soil, says Sparks, and promotes good plant growth. However, it has no effect on TSWV.

The standard for managing TSWV, he says, is reflective plastic mulch. “It is a very shiny, basically aluminum-coated plastic mulch. It reflects UV light, and it repels thrips and makes it hard for them to find the plant. It has an obvious effect on reducing TSWV, but it also has an obvious effect on reducing plant growth because we’re not heating the soil,” says Sparks.

A combination of the two types is the heat-strip plastic mulch. It has a black strip down the middle that heats the soil where the transplants are planted. “The silver shoulders hopefully will give you enough light to repel thrips and reduce TSWV.”