Received the first sample of the season of tomato spotted wilt virus from northern Livingston Parish. It was found in two locations several miles apart. Both samples were of Celebrity tomatoes that had not even set fruit yet. This virus is transmitted by thrips and generally acquires the virus from weed hosts like the pasture buttercup, which has been abundant this year because of the early warm weather. Only the immature thrips can acquire the virus, which is then transmitted by the adults once they develop. Chemical control of the thrips is not particularly effective in reducing spread because by the time the adult contacts enough of the insecticide to kill it, it has already transmitted the virus.
Donald M. Ferrin, Ph.D., Louisiana State University Agricultural Center, Baton Rouge, LA