Field Corn, Northern and Western Corn Rootworm Control, 1984

Tests were conducted at the PA Agricultural Experiment Station Farm at Rock Springs, Centre Co, and on the Yahner Farm, Cambria Co and the Lewis Farm in Erie Co. The test fields had been in continuous corn for 3 or more years. Corn was planted on 24 May (Doebler’s 58x), 5 Jun (Funk’s 4252) and 25 May (Pioneer 3901) at the 3 locations respectively. Mixed populations of the 2 rootworm species were present at each location. Western corn rootworms were least abundant at the Centre Co site. All treatments were planted with no-till planters. Row spacings were 30 inches at Centre and Erie Counties and 38 inches at Cambria Co. Insecticides were applied to 15 x 90-ft plots in Centre Co, 5 x 90-ft plots in Erie Co and 6.3 x 100-ft plots in Cambria Co in randomized complete block design with untreated checks in 4 replications. Seven insecticide-rate combinations were applied using either in-furrow or the banded method of application. Stand germination counts were made and then all rows were thinned at each site to a standard density. The sites were not comparable in density. The treatments were evaluated for root damage ratings based on the Iowa 1-6 system on 24 Jul, 2 Aug and 1 Aug at the Centre Co, Erie Co and Cambria Co sites, respectively. Stalks were also examined for other insect pests, none of which were prevalent during crop development. Yield was determined by mechanically harvesting 2 rows of each plot for shelled corn.