EFFICACY OF VACUUM MACHINES FOR LYGUS-HESPERUS (HEMIPTERA, MIRIDAE) CONTROL IN COASTAL CALIFORNIA STRAWBERRIES

Three representative suction machines were evaluated for control of Ly gus hesperus (Knight) on strawberries for two growing seasons in produ ction fields. Weekly and twice-weekly vacuum passes through a field we re compared with bifenthrin applications in 1989. Weekly and twice-wee kly vacuum passes were compared with bifenthrin (0.11 kg [AI]/ha) and malathion (1.26 kg [AI]/ha) sprays applied using a degree-day phenolog y model and with a combination of malathion and weekly vacuuming in 19 90. All three machines reduced damage caused by L. hesperus when compa red with the untreated control. The three-bed vacuum is the largest ma chine, with the highest air flow, tested, resulting in a significant r eduction in damage compared with the untreated. The smaller one-bed an d two-bed machines did not decrease the numbers of nymphs or damage. H owever, the treatments in which vacuum machines were used exclusively had damage that was not economically acceptable. Twice-weekly vacuum p asses did not improve L. hesperus control compared with weekly vacuum passes. Weekly vacuum passes combined with malathion sprays were no be tter than either treatment alone. Bifenthrin provided effective contro l but resulted in spider mite (244.6 mites per leaflet) population inc reases after 3-4 wk. Weekly vacuum treatments provided control of L. h esperus equal to that of one or two applications of malathion.