The tomato spotted wilt virus (TSWV) is one of two important viral diseases of tomatoes. Tomato plants infected with TSWV exhibit varied symptoms. Plants may show dark blotchy spots and stunted growth, and young leaves may roll upward with veins tinged purple.
TSWV is transmitted by thrips (insects), which acquire the virus from winter/spring weed hosts near the field or garden. Sap ingested from infected weeds contains the virus, which develops inside the insect. The adult insect then spreads the virus when feeding on the young growing tomato plants. Field buttercup (Ranunculas spp.) and sow thistle (Sonchus spp.) have been shown to harbor the virus. It is difficult to control the disease. Once infected plants are found, it is best to remove the plants from the field/garden and destroy them.
Early season control of thrips using recommended insecticides may reduce the severity or incidence of TSWV. Contact your local Extension office for insecticide recommendations. Also, purchase tomato transplants that are labeled TSWV resistant.
