By Terry Kelley
University of Georgia
Tomato spotted wilt virus has become one of the greatest challenges home gardeners face each year. In fact, the disease often seems to be worse in home gardens than in commercial plantings.
This disease can affect both peppers and tomatoes. Young leaves usually turn bronze and later begin to develop small, dark spots. The growing tips of the tomato die back and the stems of terminals may become streaked. Some plants may have a one-sided growth appearance or be stunted overall.
Plants infected early usually do not develop fruit. Those infected later in the season may produce fruit that is knotty. Mature fruit may have light-colored ring spots, and green fruit may have bumpy areas with faint concentric rings. As the fruits mature, the rings become more apparent and turn red and white or red and yellow.
The disease is spread by thrips as they feed on the plant. Controlling thrips at a level to prevent infection is almost impossible. The virus is usually transmitted before residual insecticide sprays kill the insect.
The disease also has numerous alternate hosts. It may survive in many weed species as well as other crops such as peanuts and tobacco.
Commercial growers have more tools to reduce the incidence and severity of the disease than do gardeners. As with almost any virus, the most effective control is the use of resistant varieties. Not all of the resistant varieties are available to gardeners since the seed of some must be purchased in large quantities. More options are becoming available to gardeners, however.
For tomatoes, Amelia, BHN 444, BHN 640, Bella Rosa, Top Gun, Crista, Mountain Glory, Muriel and Red Defender are all available in some garden catalogs. Muriel is a Roma type tomato.
Excursion II, Declaration and Plato are available pepper varieties.
Some sources of these seed include Harris Seeds (www.harrisseeds.com), Twilley Seed (www.twilleyseed.com) and Rupp Seeds (www.ruppseeds.com).
Other resistant varieties usually not sold in small quantities include Magico, Stiletto and Heritage peppers and Talladega, Redline, Finishline and Quincy tomatoes.
Another way to get resistant varieties is to look for seedlings at your favorite garden center. Some of the varieties not sold in small quantities as seed may be found in this manner. You also may need to look for them sold under a different variety name. Southern Star produced by Bonnie Plant Farms is one such variety and is actually BHN 640.
One drawback to using these varieties is that they probably won’t have quite the flavor of your old favorite garden variety. They were bred for commercial production and shipping. If you let them ripen on the vine, they will be fine. Buy from reputable sources as well, since selling nonresistant varieties as TSWV resistant plants has been known to occur.
Producing your own transplants from seed is the best way to ensure that you have TSWV resistant plants available. You may want to join with other gardeners in your area to produce enough plants for several people. It’s probably not too late to order seed and get started. These varieties can ease the challenge of growing tomatoes and peppers in the home garden.
To control thrips, use black or reflective plastic mulches around the tomatoes. Aluminum foil might be a suitable substitute since the actual plastic reflective mulches are expensive and hard to find. Even straw mulches may help a little. Also, keep weeds around the garden under control as they may be a host for the disease.
(Terry Kelley is a former University of Georgia Cooperative Extension horticulturist with the UGA College of Agricultural and Environmental Sciences.)