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44th TWC, Tob. Work. Conf., 2010, abstr. 71

Incidence of tomato spotted wilt virus in Burley and flue-cured tobaccos in eastern North Carolina

BOCK M.B.; SORENSON C.E.
University of Kentucky, Lexington, KY, USA

Tomato spotted wilt virus (TSWV) is an economically significant disease of tobacco transmitted by several species of thrips. Anecdotal evidence from 2004- 2008 in North Carolina suggested that the incidence and severity of TSWV is greater in Burley tobacco varieties compared to the flue-cured varieties traditionally planted in the coastal plain and piedmont regions. Visual surveys were conducted in paired commercial Burley and flue-cured fields in several eastern North Carolina counties from 2007-2009; these surveys suggested that incidence was indeed higher in Burley. Small plot field tests were conducted at the Lower Coastal Plain Research Station in eastern North Carolina during the 2008 and 2009 growing seasons to evaluate the effects of tobacco type (Burley or flue-cured) planting date (early or late), and treatment with the TSWV-suppressive insecticide imidacloprid, on the incidence of TSWV transmitted by feral thrips populations. In these trials we demonstrated that incidence is approximately two-fold higher in Burley types of tobacco compared to flue-cured types under similar planting date and insecticide regimens. Greenhouse studies using mechanically inoculated Burley and flue-cured tobacco varieties then established that the higher incidence in Burley tobaccos observed in the field is due to the inherently higher susceptibility of the Burley tobacco varieties (including NC 7, the most commonly planted in eastern North Carolina) used in these studies to TSWV. Field tests to evaluate color preference of feral thrips populations, conducted at the Central Crops Research Station in central North Carolina, suggested that any thrips behavioral preference for the more yellow color of Burley tobacco (compared to flue-cured tobacco) probably makes a very minor contribution to observed differences in TSWV incidence in tobacco fields.