Balsam Fir, Control of Balsam Gall Midge, 1984

A Christmas tree plantation in Plymouth, Maine was used for the insecticide evaluations. Insecticides were applied to 0.25-acre blocks on 28 May using a Stihl SG 17 mistblower at a rate of 5 gal finished spray/acre. Insects were predominantly first instar although some unhatched eggs were present. Rain occurred 2 h after the last block was treated; however, the insecticides had dried on the foliage. Temperature at the time of application was 45-50°F. Two additional blocks were treated on 5 and 10 Jun with diazinon to provide efficacy data as gall formation progressed. No rain occurred within 24 h of either treatment and the temperature was 45-50°F at time of treatment. Counts of live larvae were made on 17 Jul to determine the level of control. The sampling unit was 2 current-year shoots taken from the upper third of the crown of 10 trees per block. Visual observations of damage were made in October.