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Efficacy of Heliothine Control Materials in B.t. and Non-B.t. Cotton

John D. Hopkins, D.R. Johnson, G.M. Lorenz, III and J.D. Reaper, III


ABSTRACT

In 2001, supplemental insecticide treatments to Deltapine 451BR (B.t. cotton variety-2 applications) and Deltapine 425R (closely related non-B.t. cotton variety-3 applications) were evaluated to determine if improved Heliothine control could be demonstrated. Insecticides evaluated on both Deltapine 451BR and Deltapine 425R were Steward 1.25SC, Tracer 4SC, Karate Z 2.08CS, and Fury 1.5EC. Vydate C-LV 3.77SL was evaluated only on Deltapine 451BR and Denim 0.16EC was evaluated only on Deltapine 425R. Low or reduced rates were used on Deltapine 451BR and standard rates were used on Deltapine 425R. The test was conducted under predominantly bollworm pressure. With the exception of Vydate C-LV 3.77SL (0.25 lb. (AI)/A), all supplemental insecticide treatments on both varieties significantly reduced Heliothine square damage. Differences in square counts for live Heliothine larvae were not observed among treatments at any time for the B.t. cotton and larval numbers were very low. In the non-B.t. cotton, all chemical treatments significantly reduced the live Heliothine larvae count in squares compared to the untreated non-B.t cotton. There was a numerical trend for reduced Heliothine terminal damage with all chemical treatments in the B.t. cotton; however, virtually no live Heliothine larvae were observed in the terminals of the B.t. cotton. All chemical treatments significantly reduced Heliothine terminal damage and counts of live Heliothine larvae in terminals in the non-B.t. cotton. On a numerical basis, Vydate C-LV 3.77SL (0.25 lb. (AI)/A), Karate Z 2.08CS (0.015 lb. (AI)/A), and Tracer 4SC (0.067 lb. (AI)/A) out yielded the untreated B.t. cotton (1232 lbs. lint/A) by 211, 106, and 100 lbs., respectively. All chemical treatments significantly out yielded the untreated non-B.t cotton (827 lbs. lint/A) and the yield increases ranged from 93 to 235 lbs. lint/A. This study suggests that increased yields can be obtained when appropriate supplemental insecticides, targeted at pests not adequately controlled by the CryIA(c) toxin, are utilized in B.t. cotton. In addition, the results of this study show that increased yields can be obtained when appropriate supplemental insecticides are utilized to control the Heliothine complex in non-B.t. cotton.





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Document last modified May 20, 2002