—/r^^ -i" -r' t' f J T'vy f '- '»^ 



364 



practices have been employed; certain of these have persisted while others 

 were discarded as ineffective, impractical, or uneconomical. The following 

 geneial description of the background and evolution of cultural controls 

 should serve to indicate the extent to which the practices may be utilized 

 in boll weevil control and management systems. 



714. Norman, J. W. , Jr.; Henson, J. L.; Wolfenbarger, D. A.; Harding, J. A.; 

 Gage, E. V.; Parker, R. D., Jr.; and Collins, G. 1979. Effects of water 

 management practices on economics of insect control on cotton. Lower 

 Rio Grande Valley, Texas. J. Econ. Entomol. 72: 367-370. 

 Data from a pest management program on cotton in dryland and irrigated condi- 

 tions was used to develop an economic evaluation of insect control in the Lower 

 Rio Grande Valley of Texas during 1973-/5. A strong economic advantage was shovm 

 for dryland production. Dryland cotton had 89% of its harvested bolls set by 

 June 19 while irrigated cotton had 88% set by July 17; thus, irrigation delayed 

 maturity. Dryland cotton required 5.5 kg/ha (4.91 lb/acre) less in;iacticide AI 

 than irrigated cotton. Lint yields for dryland cotton were 541 kg/ha (483 lb/ 

 acre) vs. 615 kg/ha (549 lb/acre) for irrigated cotton and were equal by statis- 

 tical analysis. However, production costs for dryland cotton were $266.88/ha 

 ($108.05/acre) less than irrigated cotton and dryland cotton returned net profits 



of $142.99/ha ($57.89/acre) above those of irrigated cotton. 



715. Norment, B. R. and Chambers, H. W. 1970. Joint actions in crganophosphorus 



poisoning in boll weevils. J. Econ. Entomol. 63: 499-502. 

 To analyze the joint action of binary mixtures, a laboratory culture of organo- 

 phosphorus-susceptible boll weevils, Anthonomus grandis Boheraan, were exposed 

 to insecticides, defoliants, and equitoxic insecticide-defoliant mixtures. The 

 degree of interaction in a susceptible strain of boll weevils was greater than 

 unity for equitoxic binary mixtures of DEF® (S, S, S-tributyl phosphorotrithioate) 



