272 



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Anthonomus grand Is Boheman, found in an extensive search through a broad spec- 

 trum of Gossypium hirsutum germplasni. The original Frego mutant had several 

 undesirable agronomic features. In 196A cotton-insect scouts found several 

 individual plants with rolled bracts in commercial cotton fields. Seed of 

 several of these plants were saved. After a winter increase in Mexico, Frego- 

 type cotton was planted in Arkansas in 1965. Lincoln and Waddle reported re- 

 sistance to both boll weevil and bollworm, Heliothis zea (Boddie) , from this 

 planting. Releases of 2nd-stage bollwoirms and adult boll weevils into the 

 cotton were used to obtaiii data on which these conclusions were based. Addi- 

 tional research was conducted on the rolled-bract mutation as a source of resis- 

 tance to boll weevil and bollworm. The strain used was based on the 1964 collec- 

 tions with little subsequent selection. 'DPL Smoothleaf appears to be the 

 parent variety of this strain. 



517. , and Graves, J. B. 1978. Insecticides: resistance and new insecti- 

 cides formulation and application technology. j[£ Boll Weevil: Management 

 Strategies. South. Coop. Ser. Bull. 228, pp. 74-83. 

 Boll weevil populations are not reduced sufficiently by climatic conditions 

 and biological control agents to prevent infestations from exceeding esta- 

 blished economic thresholds annually. Application of insecticides has been 

 the principal means of controlling this key pest of cotton since calcium 

 arsenate was first reported to be effective in 1918. However, widespread 

 use of the arsenicals induced outbreaks of aphids, bollworms, and presumably 

 tobacco budworm because of interference with biological control agents that 

 ordinarily controlled these insects. The synthetic insecticide revolution of 

 the 1940' s produced the first really effective insecticides for all cotton 

 pests. The increase in yield obtained from insect control vif.h the new 

 organochlorine insecticides such as DDT, BHC, toxaphene, and endrin was about 

 double that obtained with the inorganic insecticides. The striking effective- 



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