Juniper, Spruce Spider Mite Control, Knox Co., Oh, 1988

Abstract

Abstract Junipers (1.0-1.5 m high), gorwing in a nursery were used to evaluate acaricides against spruce spider mites. Treatments were assigned to plants randomly, except that the 4 single-plant replicates were chosen from throughout different parts of the plantation. Pre-counts indicated an average of 205 mites/sample. Treatments were applied with a KWH backpack mistblower operating at half throttle on aperture setting 3 for 40 s delivering ca. 920 ml of finished spray/plant. The first application was made with all treatments, except Margosan-O, 6 Jun when conditions were sunny, 29°C, with a breeze of 8-16 kph. Margosan-O was applied 15 Jun when second applications were made with all treatments, except Savey. Conditions were sunny, 31°C, with no breeze. Treatments were evaluated 2, 4, and 6 wk after the second application by removing 5, 10-15 cm long, lateral branch tips from each of the replicate plants. Samples were placed in plastic bags and put in an ice-chest for transport to laboratory. Samples were immediately processed by passing them through a mite brusher 6 times to dislodge mites to a rotating glass plate coated with Tween-20. Dislodged mites were counted with the aid of a binocular dissecting microscope.