Tomato Spotted Wilt, Quick Identification

Tomato spotted wilt virus (TSWV) has historically been a devastating disease of peanuts. Given the high thrips population this spring and large population of flowering winter weeds known to be TSWV hosts, I was expecting a TSWV year. I was wrong. Last week, I saw the first TSWV infected peanut of the season. I didn’t find it, an independent crop consultant in the greater Clarksdale area did – and wishes to remain anonymous. So how do we tell a peanut plant infected with TSWV from a peanut plant that is expressing a genetic abnormality?

The image on top shows some peanut leaflets expressing genetic abnormalities, whereas the image on the bottom shows leaflets that harbor TSWV. Note the TSWV symptoms include small, circular patterns, called ringspots. Genetic sports only rarely have a single such ringspot symptom. If you really want to know if the plant is infected with TSWV, I can test it for you (using an antibody test).

Abnormal white and green pattern expressed by occasional peanut plants in the field.

Peanuts infected with TSWV usually show good ringspot symptoms, as shown in this image. Note the large (eye-shaped) symptoms on the leaflet second from the left, and the small ringspots in the center and right leaf.