A Threshold Management Test with Nucotn 33B, 1996

Abstract

Abstract Plots were replicated four times in a RCB design and were eight rows (40 in spacing) X 45 ft. Transgenic cotton seed expressing the Bt delta endotoxin and seed of the non-transgenic parent line (DP 5415) were planted on 15 May, on a Commerce silt loam soil which was fertilized with 90 lb N/acre. Cotton seed was planted with a John Deere 7100 series planter which was equipped with 10 inch seed cones mounted to replace the seed hoppers. The seeding rate was 4 seed/row ft. Granular in-furrow treatments were applied with 8 inch belt cone applicators. In-furrow spray treatments were applied with a CO2 charged spray system through 25015 flat fan nozzles positioned in front of the press wheels. The spray tips were turned to spray across the furrow and were calibrated to deliver 5 gpa finished spray. All plots received 0.5 lb (AI)/acre Temik 15G and 0.75 lb (AI)/acre Terraclor Super X 2E at planting. Insecticide control measures were applied to treatments when boll worms and tobacco budworms first deposited eggs in Jul, and at 2, 5, and 7 percent BW/TBW/BAW damaged squares. The test was conducted in the presence ol high boll weevil population densities. Beet army worms were present in late Jul, Aug and Sep. Control of boll weevils and tarnished plant bugs was maintained on an “as needed” basis using the following treatments: Methyl parathion 4E, (0.33 lb (AI)/acre) on 11 Jul; Vydate 3.77CLV, (0.25 lb (AI)/acre) on 30 Jul; Methyl parathion 4E, (0.33 lb (AI)/acre) + Orthene 90S, (0.33 lb (AI)/acre) on 6 Aug; Methyl parathion 4E, (0.33 lb (AI)/acre) + Dimethoate 4E. (0.25 lb (AI)/acre) on 13 Aug; Baythroid 2E, (0.045 lb (AI)/acre) on 11 Sep. In addition to the overspray treatments listed above, the DP 5415 and NuCOTN 33B spray strategies (treatments 2 and 4) received the following insecticide treatments: Karate IE, (0.03 lb (AI)/acre) on 22 Jul; Karate IE, (0.03 lb (AI)/acre) on 25 Jul; Karate IE, (0.03 lb (AI)/acre) on 30 Jul; Karate IE, (0.03 lb (AI)/acre) on 5 Aug; Karate IE, (0.03 lb (AI)/acre) on 8 Aug. Cu-racron 8E, (1.0 lb (AI)/acre) + Pirate 3E, (0.2 lb (AI)/acre) + Vydate 3.77CLV, (0.25 lb (AI)/acre) on 15 Aug and Curacron 8E, (1.0 lb (AI)/acre) + Pi-rate 3 SC, (0.2 lb (AI)/acre) + Methyl parathion 4E (0.33 lb (AI)/acre on 26 Aug. Bollgard® threshold treatments 2% and 5% were sprayed with Karate IE, (0.033 lb (AI)/acre) on 8 Aug and Curacron 8E (1.0 lb (AI)/acre) + Pirate 3 SC (0.2 lb (AI)/acre) + Vydate 3.77 CLV, (0.25 lb (AI)/acre) on 15 Aug. All NuCOTN 33B threshold treatments were sprayed with Baythroid 2E (0.045 lb (AI)/acre), on 11 Sep. Plant terminals and squares were examined for BW/TBW eggs, larvae, damage and boll weevil damaged squares on 11, 24, 30 Jul, and 2, 8, 13 and 19 Aug. Terminals were examined on all dates except 19 Aug. The center four rows of the plots were harvested on 14 Oct to determine seedcotton yield. Plots were harvested using a John Deere spindle type picker. Yields were converted to lb seedcotton/acre.