Disease guide

Tomato spotted wilt virus (TSWV)
Several strains have been reported.

Thrips (Thrips tabaci and Frankliniella species)

The first visible symptom is small, orangish-yellow flecks on the older leaves. Later. the leaves develop small, dark, more or less circular spots, which gives them a bronzed appearance. The growing tips of the leaves may die as the disease progresses. Dark, shiny streaks are often seen along the stem and petioles. Severely infected plants are stunted with yellowish drooping foliage, which imparts a wilting appearance to the plant. Fruit usually show characteristic green. yellow and red, slightly raised concentric rings, although some strains can cause severe necrosis.

This virus has a very wide host range from which it can be transmitted in a persistent manner by thrips. Although the virus is acquired at the larval stage, it is only spread by the adults that are wind blown to tomatoes from infected weeds or ornamental plants. Usually, there is very little spread within a tomato crop.

Elimination of thrips and host weeds through insecticide and herbicide applications is important for disease control. Resistant varieties should be used when possible.