Taxus, Black Vine Weevil Control, Wooster, Ohio, 1977

Efficacy of insecticides for control of black vine weevil adults was evaluated by laboratory bioassay of foliar residues collected from the field at specified intervals. Finished spray was applied to runoff with a C02 compression sprayer operating at 50 psi with a Tee Jet SS8004 flat fan nozzle between 9:00 A.M. and 12:00 noon (EDT) on July 26, 1977 under sunny skies at 19°C with a slight breeze (8-12 kilometers/hr)- Small portions (0.5-1.0 m wide) of Taxusmedia ‘Hatfieldi’, 3+ m high, growing in the Secrest Arboretum at Wooster were thoroughly sprayed with each candidate material. One day later, 3 10-15 cm twigs were clipped from each treatment area and placed individually in 9 x 16 cm cylindrical paper cartons fitted with a screen lid. Five ovipositing weevils were added to each container; containers were held in the laboratory at ca 22°C, 15 hr light/day, and ambient humidity. All weevils used were previously field collected in the Wooster area and held in a rearing chamber with fresh taxus foliage at approximately the above conditions. Additional bioassays were conducted at intervals given in Table 1. Mortality was assessed 72 hr after caging weevils with sprayed foliage.