Cankerworm Control in Shelterbelts, Walhalla, North Dakota, 1973

Abstract

Abstract Each insecticide was applied from the air to 1 of 8 one-half mile long single row belts. There were approximately 100 yds between belts. Pre-treatment larval counts were made from five randomly selected 2 ft twigs on each side of 5 frees along each belt on May 29. Twig samples were taken from eye level to approximately 20 ft above ground level. Larvae were in the 1st to the 3rd instar and averaged 22.5/2 ft twig. Cankerworms were significantly more abundant on Siberian elm than on American elm. There were approximately 2 spring cankerworms to 1 fall cankerworm. Treatments were applied May 30. Post-treatment larval counts were similarly made on June 8. The materials were applied with 44, D-7 nozzels at 38 psi and 115 mph. Three gals of water were applied/acre. Imidan 1EC, Imidan 70W and Imidan 5W were applied to American elm. The rest were applied to Siberian elm. The untreated check belt was American elm. Wind speed at application was 5 mph, and rainfall was light during the period between application and post-treatment counts. Data consisted of % reduction in cankerworm counts between pre- and post-treatment counts. No reduction in cankerworms was assumed when post-treatment counts were equal to or greater than pre-treatment counts. The arcsin transformation was applied to the data. Treatments were compared with a series of “t” tests for paired comparisons.