Bull. Spec. CORESTA Congress, Lisbon, 2000, p. 63, AP13

Impact of thrips management practices on the incidence of spotted wilt on flue-cured tobacco

University of Georgia, Coastal Plain Experimental Station, Tifton, GA, USA
Tomato spotted wilt tospovirus (TSWV) has become a major economic problem of tobacco in Georgia, USA. Several species of thrips have been reported as vectors of TSWV. Three of these species are commonly observed on tobacco in Georgia, and include Frankliniella fusca ( Hinds), F. occidentalis (Pergande), and F. bispinosa (Morgan). The objective of this study was to examine the effectiveness of several thrips management practices on controlling thrips populations and suppressing the incidence of TSWV symptomatic plants. Replicated field plots were used to evaluate aldicarb, carbofuran, acephate, imidacloprid, acibenzolar-S-methyl and thiamethoxan, alone, and in combination, applied as pre-plant incorporated, tray drench, transplant water or foliar treatments. The effects of transplanting date and volunteer peanuts also were examined in some trials. Plots were monitored weekly for the presence of thrips, and thrips were collected on every other sampling date, placed in a buffer solution and returned to the lab for identification and tested with ELISA to confirm TSWV infection. All plants in each plot were also examined for TSWV symptomatic plants each week. Acibenzolar-S-methyl (Actigard) plus imidacloprid (Admire and Provado) was the best treatment in reducing TSWV in tobacco, although each product alone was also effective. Actigard (a plant activator that enhances the plant's defense mechanism) did not affect thrips populations. Imidacloprid, acephate, and thiamethoxan reduced thrips densities and TSWV symptomatic plants when 3-6 applications were made during the first 6 weeks after transplant.