A two-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 the growing years 1993 and 1994. Respondents were licensed growers with at least 93 m2 (1000 ft2) of growing area. The objectives of the study were to develop a grower demographic profile; determine the incidence of pest thrips species with specific focus on Frankliniella occidentalis and two thrips-vectored tospoviruses, tomato spotted wilt and impatiens necrotic spot; and identify current thrips management strategies. The surveys indicated that greenhouse growers in Maine are seasonal, experienced, and retail-oriented; their growing areas average less than 929 m2 (10 000 ft2); they produce a diverse crop mix; and they choose to import production stock as much as propagate it themselves. Approximately one-third of the surveyed growers detected thrips in both years. The severity of thrips and tospoviruses has increased in Maine greenhouses over the past 10 years. Larger, year-round greenhouses are more likely to have infestations of thrips and higher virus incidence. The majority of surveyed growers employed an integrated pest management strategy. Ninety percent 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 biological control.