A 2-YEAR GROWER SURVEY OF THRIPS AND TOSPOVIRUS INCIDENCE AND MANAGEMENT IN MAINE GREENHOUSES

Two mail surveys determined the presence and importance of pest thrips species and Tospovirus in Maine greenhouses for growing years 1993 an d 1994. Respondents were licensed growers with at least 93 m(2) (1,000 ft(2)) of growing area. The study's objectives were to develop a demo graphic profile; determine the incidence of pest thrips species with s pecific focus on Frankliniella occidentalis Pergande and two thrips-ve ctored tospoviruses, tomato spotted wilt and impatiens necrotic spot; and Identify current thrips management strategies. The surveys indicat e that greenhouse growers in Maine are seasonal, experienced, and reta il oriented; their growing areas average less than 929 m(2) (10,000 ft (2)); they produce a diverse crop mix; and they choose to import produ ction stock as much as propagate it themselves. Approximately one-thir d of the surveyed growers detected thrips in both years. The severity of thrips and tospoviruses has increased in Maine greenhouses over the past 10 yr. Larger, year-round greenhouses are more likely to have in festations of thrips and higher virus incidence. The majority of surve yed growers employed an integrated pest management strategy. Ninety pe rcent of growers used insecticides to control thrips. Less than 6% of growers used natural enemies to manage thrips. However, 64% of growers responded that future research in pest management should focus on bio logical control.