CORESTA Meeting, Agronomy/Phytopathology, Krakow, 2007, AP 41

Managing thrips vectors and tomato spotted wilt tospovirus symptom expression in flue-cured tobacco

University of Georgia, Dept. of Plant Pathology, Tifton, GA, USA.

Tomato spotted wilt tospovirus (TSW) is a serious economic problem for tobacco producers in Georgia, USA. This virus is spread, or vectored, by tiny insects called thrips ( Thysanoptera : Thripidae ) as they feed on the crop. Results are presented from replicated field trials conducted in flue-cured tobacco in 2001-2006 to assess whether certain pest management practices and production modifications can impact the incidence of TSW symptomatic plants. TSW was significantly lower in plots protected from early-season thrips infestations during the first 6-8 weeks after transplanting using either weekly foliar sprays of acephate or thrips exclusion cages. Tray drench applications of imidacloprid and other neonicotinoid compounds, applied to greenhouse-produced plants 3-5 days before transplanting, also reduced TSW symptom expression in every year of the study. Nitrogen fertility level (from 0 to 135 kg/ha) did not affect TSW incidence in most years. The tobacco thrips, Frankliniella fusca (Hinds), a reported vector of TSW, was the predominant thrips species on tobacco foliage. However, low numbers of other species also were observed. Yellow sticky cards were used to monitor the presence of thrips in the farmscape throughout the season. Most thrips movement within the field occurred between 0900h and 1600h, and more were captured on the eastern side of the sticky card. Flower thrips species ( F. occidentalis, F. tritici, and F. bispinosa , combined) were more abundant on sticky cards than F. fusca , but flower thrips were not common on tobacco foliage.