Tob. Sci., 1997, 41-14, p. 94-102, ISSN. 0082-4523

Influence of dichloropropene, volunteer peanuts, and thrips control practices on the abundance of insect pests and incidence of tomato spotted wilt in flue-cured tobacco

Departments of Entomology and Plant Pathology, University of Georgia, Coastal Plain Experiment Station, Tifton, GA, USA

The influence of dichloropropene (Telone II), volunteer peanuts (Arachis hypogaea L.), and thrips control practices on insect pest populations, tomato spotted wilt virus incidence, and yield of flue-cured tobacco (Nicotiana tabacum L.) were examined in field plots in 1995 and 1996. A pre-plant fumigation of dichloropropene did not affect the seasonal mean populations of thrips (primarily Frankliniella fusca (Hinds)), tobacco aphids (Myzus nicotianae Blackman), or tobacco budworms (Heliothis virescens (F.)) either year. Acephate and imidacloprid foliar insecticide treatments reduced the thrips and aphid populations, while acephate and Bacillus thuringiensis (B. t.) reduced overall budworm populations in 1995. Acephate effectively reduced these insect pests in 1996. The seasonal mean incidence of tomato spotted wilt was reduced in the dichloropropene plots (22.7%) compared to the no dichloropropene plots (30.6%) in 1995, but no differences were detected in 1996 when infection rates were below 10% in both treatments. Four foliar applications of acephate during the early season reduced tomato spotted wilt infection (19.6%) compared to the non-treated plots (30.1%) in 1995 and also in 1996 even though infection rates were low (3.5% with acephate, 7.3% without acephate). Acephate applications enhanced cured tobacco yields both years of this study. Dichloropropene fumigation did not alter the tobacco grade index, but grades were higher in the acephate and B.t. plots compared to tobacco not treated with foliar insecticides. Volunteer peanuts did not influence thrips or aphid population densities, spotted wilt incidence, or cured tobacco yields. It appears that intensive early-season thrips control practices will aid in reducing the incidence of tomato spotted wilt virus and the thrips that vector this disease in flue-cured tobacco. However, effectively managing this complex vector/virus problem will require combining foliar thrips control with other production practices including cultivation, transplanting date, cultivar selection, management of overwintering thrips populations, and possibly fumigation and other pest management and crop production concepts.