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While there are many plant diseases that make growing tomatoes a challenge in the Southeast, a relatively new disease threatens to make homegrown tomatoes almost impossible for many local gardeners.
Tomato Spotted Wilt Virus (TSWV) is different from most tomato diseases because it is caused by a virus rather than a fungus or bacteria. Most virus diseases in plants cause the infected plant to show strange color patterns on the leaves or flowers and may cause stunting, but usually do not kill their host plant outright.
Unfortunately, TSWV does, and it has started showing up on tomato plants throughout our area in the past few weeks.
Tomato plants infected with TSWV wilt and die rapidly. Take a really close look and you’ll notice unusual markings on the leaves. Sometimes these markings look like brown or black spots. Other times they look like tattooed lines or circles.
Usually these symptoms show up on the top leaves of the plant first, whereas most other tomato diseases show up on the lower leaves first. There is no way to treat TSWV and infected plants should be pulled up and discarded.
Like most plant viruses, TSWV is spread by insects. There are several types of insects that can spread plant viruses, including aphids and plant hoppers, but the insect that spreads TSWV is a tiny little critter called thrips.
Thrips are difficult to control and treating for thrips will not prevent them from transmitting the disease to your plants. This is because thrips transmit TSWV quickly when they begin to feed on a plant with their needle-like mouthparts. The disease is transmitted before pesticides are able to kill the critter.
The only way to combat TSWV is to plant varieties of tomatoes that are resistant to the disease. Unfortunately, old favorites like Celebrity and Better Boy and heirloom varieties such as German Johnson and Homestead have no resistance to this disease.
There are several new varieties that have been bred for TSWV resistance and are available from area garden centers. These include Amelia, Crista, Bella Rosa, Talladega, BHN 444, BHN 640 and Muriel.
If you have lost your tomato plants to TSWV this year, it is not too late to replant with a resistant variety, but that does not guarantee you will not have other disease problems. Both Bacterial Wilt and Southern Blight can cause tomato plants to wilt and die, and there are several diseases that will cause the leaves on tomato plants to turn brown and yellow.
If your tomato plants begin to wilt or show other disease symptoms, drop a sample by the Extension office in Bolivia and we’ll help you figure it out.
Al Hight is the county extension director and horticulturist with the Brunswick County Cooperative Extension Service. Call 253-2610 or e-mail firstname.lastname@example.org.