(F38) CORN (FIELD): Zea mays L. 'AG 295, Pioneer 3751' Northern corn rootworm (NCR); Diabrotica barberi (Smith and Lawrence) Western corn rootworm (WCR); Diabrotica virgifera virgifera (LeConte) E. J. Shields and A.M. Testa Department of Entomology Cornell University Ithaca, N.Y. 14853 (607) 255-8428 Email:
[email protected] CORN ROOTWORM CONTROL IN FIELD CORN, 1993: Two insecticide studies for controlling mixed populations of NCR and WCR were conducted on two separate research farms. Experimental plots measuring 15 rows x 100 ft were planted at Agway Research Farm, Tully, N.Y., on 10 May. Experimental plots measuring 41 rows x 100 ft were planted at Musgrave Research Farm, Aurora, N.Y., on 20, 21 May. Corn was planted with a 2- row planter at 31,000 seeds/ acre, and fertilized with 400 lb of 10 - 10 - 10 fertilizer banded at planting. Soils were silt loam with 4 % organic matter. Soil PH at the Tully site was 6.7 and 8.0 at the Aurora site. Each treatment was a single row by 100 ft. All treatments in each study were replicated four times in a CRB. Supplemental nitrogen was provided with a preplant incorporated application 300 lb urea. Granular insecticides were applied at planting (AP) with Noble granular applicators mounted on the planter. Stand counts were taken 100 row ft. on 22 Jun in Aurora. Five plants in each row were dug and the roots washed before rating root damage using the Iowa 1 - 6 root rating scale on 5 Aug in Aurora and on 6 Aug in Tully. Treatments were mechanically harvested on 8 Nov in Tully and on 12 November in Aurora. Harvesting was done with a single row silage chopper (New Holland model 707), and the silage from each treatment row was collected and weighed. Significant differences between treatments were noted at both locations in root ratings, silage yields, and stand counts.
