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Comparison of Different Chemistries and Rates Against Bollworm in Bt and Conventional Cotton

D. S. Brickle, S. G. Turnipseed and M. J. Sullivan


 
ABSTRACT

Six insecticides of different chemistries were evaluated against the cotton bollworm (Helicoverpa zea [Boddie]) in conventional (Deltapine® 'DP 5415', Deltapine® 'DP 5415RR') and transgenic Bacillus thuringiensis (Berliner) (Deltapine® 'NuCOTN 33B', Deltapine® 'DP 458 B/RR') cotton. In 1998, treatments consisting of three rates each of a pyrethroid (Karate-Z®), spinosyn (Tracer®), carbamate (Larvin®), pyrrole (Pirate®), oxadiazine (Steward®), and avermectin (Proclaim®) were established in a non-irrigated field. In 1999, treatments consisted of three rates each of Karate-Z®, Tracer®, Larvin®, and Steward® in an irrigated and a non-irrigated (dryland) field. The highest rate of each insecticide corresponded to normal grower-use rates. Tracer® and Larvin® controlled H. zea in conventional cotton, whereas other materials were less effective. Even though H. zea is becoming increasingly resistant to pyrethroid insecticides, Karate-Z® was highly effective in dryland B. thuringiensis (B.t.) cotton. Tracer® and Larvin® were equally effective. Data indicated that reduced rates of Karate-Z®, Tracer® and Larvin® could be used for control of H. zea in dryland B.t. cotton systems. However, reduced rates of these insecticides in an irrigated B.t. cotton system did not provide adequate control.



Reprinted from Proceedings of the 2000 Beltwide Cotton Conferences pp. 971 - 975
©National Cotton Council, Memphis TN

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Document last modified Saturday, Jun 17 2000