Thrips are able to transmit TSWV very quickly, and most of these virus-carrying thrips come from outside the tobacco field. Over-the-top insecticides do not kill these thrips quickly enough to stop the spread of the virus. This type of spraying has not been successful in reducing disease incidence. However, some disease suppression has been noted on imidachloropicrin-treated plants in Georgia and North Carolina. Therefore, applying Admire in the greenhouse to control aphids and other insect pests may help suppress TSWV.
The application of Actigard, alone or in combination with an insecticide, as a foliar spray (drench) to seedlings in the greenhouse shows promise for being an effective and economical management tactic. Most economically important TSWV infections apparently occur within the first week or two after transplanting; many may occur during the first few days. Thus, protection should be in place before transplanting. Application of any chemicals after the virus has infected the plant will be of little, if any, benefit. The best treatment in our studies averaged about 45 percent control.