Even plants can have a virus – Spotted wilt of tomato

Ruth Correll • Dec 17, 2015 at 6:40 PM

Summertime officially arrives on June 21. Summertime is synonymous with gardening and this season brings UT Extension agents many questions in regard to garden issues and insects. Folks are already bringing garden plants with obvious disease or insect issues by the office seeking solutions to the problems. Case in point being a recent tomato sample which was diagnosed with a virus…the tomato spotted wilt to be exact.

Spotted wilt of tomato is caused by the tomato spotted wilt virus (TSWV), and the virus is spread by tiny insects called thrips. Initial symptoms include, young leaves which show bronze to purplish specks and rings and become brown and dry. Early symptoms appear on the younger leaves and toward the top of the plant. Brown, corky areas may appear on the stems. 

This virus can affect, the leaves, the stems and the fruit. Infected plants may be next to healthy plants. Plants infected while young become pale and stunted and show rolled leaves with purple veins. If infected after the presence of fruit, the fruit is marked with yellow rings and/or a rough, brownish surface. 

Usually significant problems with spotted wilt occur only in summers following abnormally dry springs but that is not the case for this year in Wilson County as this spring has not been especially dry in general. You cannot treat the infected plants and it cannot be cured. Also, efforts to slow spread of the disease via insecticide applications are sometimes unsuccessful.

It is recommended that infected plants not be removed, as sometimes plants grow out of the condition and produce normal fruit. A good cultural practice is to prevent winter weeds or plow them under well in advance of planting tomatoes, so that overwintering thrips do not move into the new crop of tomatoes. There are weeds that serve as hosts to thrips and also weeds that can be infected with the TSWV. Garden weed control is important in helping prevent this problem. 

Resistant varieties are available and selection of those varieties is recommended. Consult your favorite seed catalogs or read the label on transplants to select resistant varieties. Be aware that spotted wilt resistant varieties are not totally resistant, and additional control measures may be needed such as insecticides to control the virus carrier. Insecticides containing spinosyn are recommended to help the thrips. (Reference:  Dr. Steve Bost, UT Extension)

For additional information on these and other topics, contact the UT Extension Office, 925 East Baddour Parkway, Lebanon, TN 37087, 615-444-9584 or acorrell@utk.edu.  UT Extension pro-vides equal opportunities in all programs.  Visit the UT/TSU Extension webpage at http://utextension.tennessee.edu... or look for UT & TSU Extension, Wilson County on Facebook.

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