Abstract
Abstract Norway spruce (0.5-1.0 m tall) growing in a Christmas tree plantation were used to evaluate insecticides against eastern spruce gall adelgids. Four single-tree replicates, each with at least 4 recent galls, were sprayed with each treatment. A KWH backpack mistblower operating at half throttle on setting 3 for 30 s delivered 946 ml of finished spray to each tree. Sevin 80 S was applied 1 Oct, when adelgids were active on twigs, but hatching was not complete. An additional treatment was applied 14 Oct, along with the other treatments, when hatching was complete. Conditions on both spray dates were sunny, 15-18°C, and 8-16 km/h breeze. Treatments were evaluated 12 Nov by randomly removing 4 8-12-cm-long, lateral branch tips having at least 1 gall for each of the 4 replicates/treatment. Samples were placed in plastic bags and transported in an ice chest to the laboratory. Samples were immediately processed with the aid of a dissecting microscope by assessing the percentage of twigs with galls having live adelgids near buds. All buds were examined for presence of adelgids.
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