Be on the Lookout for Tomato Virus

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Leaves of tomato plants infected with TSWV develop brown or black spots and curl upward. The disease starts at the top of the plant and is vectored by a nearly invisible insect called thrips. Plants stop growing and eventually die. There is no cure for viral diseases, so it's best to rip up infected plants.

Leaves of tomato plants infected with TSWV develop brown or black spots and curl upward. The disease starts at the top of the plant and is vectored by a nearly invisible insect called thrips. Plants stop growing and eventually die. There is no cure for viral diseases, so it’s best to rip up infected plants.

Tomatoes are one of the most beloved home garden crops, but they can be difficult to grow. Among its problems is a viral disease called tomato spotted wilt virus (TSWV). We’ve had a few samples come into the office recently that are infected with the virus.

Tomato spotted wilt virus is a disease that was first documented in Australia in 1918. The disease was first reported in North Carolina in the mid-‘90s. Like most viral diseases, symptoms of TSWV include strange patterns of discoloration on both leaves and fruit. However, most other viral diseases of tomatoes will not kill the plants, whereas TSWV will.

Unlike most tomato diseases, these symptoms tend to start at the top of the plant, not the bottom. At first, TSWV-infected plants may seem stunted and pale. Then leaves curl inward, and spots develop on leaves and/or fruit. Sometimes the spots are black or brown, but they may also resemble tattoo markings.

In later stages, plants may appear bronze. They eventually wilt and die.

TSWV is spread by a tiny insect called thrips. Thrips are impossible to control outdoors, and weeds provide shelter for them. Keeping a garden free of weeds will reduce the chance of plants becoming infected with TSWV.

Over 800 species of plants can be affected by TSWV. It is less common in cherry tomatoes than other types of tomatoes, and varieties have been developed which are resistant to the virus. They include Amelia, Bella Rosa, Crista, Finish Line, Fletcher, Mountain Glory, Primo Red, Quincy, Red Defender, and Talladega.

Because TSWV is fatal, and there is no treatment, the best a gardener can do is remove the infected plants and replant with resistant varieties. Fortunately, at this point in the season, it is not too late to plant tomatoes.

So what can you do if you think your tomatoes are infected with TSWV? Since there is no treatment for the virus, you may want to get a second opinion by bringing a sample to the Extension office in Lenoir. A diagnosis is only as good as the information provided, so be sure to provide a complete sample. For best results, dig up the plant, place it in a plastic bag, and deliver it to the office immediately.

For answers to your gardening questions, contact the Caldwell County Extension Service at 828-757-1290 or visit caldwell.ces.ncsu.edu.

Written By

Photo of Amanda TaylorAmanda TaylorArea Specialized Agent, Nursery and Greenhouse, Western Region Serves 28 CountiesBased out of Burke County(828) 475-2915 amanda_jo_taylor@ncsu.eduBurke County, North Carolina
Posted on Jul 2, 2014
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