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Two rates of Dimilin 25W (diflubenzuron) and an untreated check were compared for effectiveness in controlling Rhyacionia bushnelli in a 1.0 ha planting of ponderosa pine in the Nebraska National Forest, Bessey Ranger District, near Halsey, NE. Trees were 2 to 3 m tall. Insecticide treatments consisted of foliar sprays of Dimilin 25W applied to 3 trees per block at either the label rate or one-half the label rate. Treatments were replicated 4 times in a randomized complete block design. Insecticide applications were applied using compressed air sprayers on 1 Jul and 8 Jul. The timing corresponded to the period in which second-generation larvae were exposed on the branch tips. Numbers of newly infested tips in the lower 2 m of each tree were determined on 6 Aug. Additional treatments at 2 and 4 times the label rate were applied to detect possible phytotoxic effects. |
