control the boll weevil and the cotton leafworm, Alabama argillacea (Hbn.). Re- 

 sults of this study were as follows: 



(1) BHC, heptachlor, and aldrin were completely ineffective in controlling 

 the boll weevil following a 24-hour exposure of treated plants to 0.87 inch of natu- 

 ral rainfall. Appreciable control was obtained with toxaphene and dieldrin under 

 these conditions. 



(2) A 24-hour exposure of treated plants in outdoor shade at high tempera- 

 ture greatly reduced the residual effectiveness of BHC, heptachlor, and aldrin 

 when used to control the boll weevil. High temperature alone caused practically 



a total loss in insecticidal toxicity; hence, sunlight was not an important factor in 

 reducing the effectiveness of these materials. Toxaphene and dieldrin retained 

 considerable toxicity in outdoor sunlight at high temperature. Sunlight did not 

 affect the toxicity of toxaphene, while it was an important factor in reducing the 

 toxicity of dieldrin. 



(3) Increased dosages of toxaphene, BHC, heptachlor, and endrin slightly 

 increased the initial control of the boll weevil, but not sufficiently to justify the 

 use of the increased dosages. When treated plants were exposed for 48 hours to 

 outdoor weather conditions, BHC and heptachlor were virtually ineffective, while 

 endrin retained a small degree of toxicity. Toxaphene retained considerable 

 toxicity under these conditions. 



(4) Repeated applications of either toxaphene or BHC at 5-day intervals did 

 not result in accumulated toxic residues which could be measured in terms of 

 either initial or residual control of the boll weevil. 



(5) When treated plants were exposed for 24 hours, indoors or outdoors, the 

 toxicity of chlorthion to the boll weevil was reduced slightly more than that of 

 toxaphene. Strobane compared very favorably with toxaphene in both initial and 

 residual control. The residual effectiveness of Bayer 17147 at a low dosage was 

 far superior to that of toxaphene. 



(6) The effectiveness of parathion or endrin in controlling the cotton leaf- 

 worm was reduced to a greater extent than that of toxaphene or calcium arsenate 

 during a 24-hour exposure of treated plants to natural climatic conditions in the 

 absence of rainfall. However, all of these materials exhibited good residual prop- 

 erties under the conditions of the experiment. One -half inch of simulated rainfall 

 applied immediately after insecticide applications was slightly more detrimental 

 to toxicant effectiveness than rain occurring 24 hours after treatment. Rain 

 slightly reduced the toxicity of toxaphene and parathion, appreciably reduced the 

 toxicity of endrin, and greatly reduced the toxicity of calcium arsenate. 



1956 - Pfrimmer, T. R., and R. C. Gaines. Field tests with insecticides against cotton 

 at Tallulah, La., in 1954. J. Econ. Ent. 49(l):72-74. 



Five experiments were conducted in plots arranged in randomized blocks, 

 with 4 replications of each treatment. Chlorinated hydrocarbons (dieldrin-DDT, 

 dieldrin-DDT -sulfur, dieldrin-DDT -parathion, heptachlor-DDT, heptachlor-DDT- 

 sulfur, aldrin-DDT -sulfur, BHC-DDT, BHC -DDT -sulfur, BHC -DDT -parathion) 

 all satisfactorily controlled the boll weevil. Several dust mixtures containing 3% 

 gamma BHC gave some control but was not as good as expected. American 

 Cyanamid 12008 and 12009 (0.25 and 0.29 Ibs./ac) and chlorthion were unsatis- 

 factory in control of the boll weevil. Heptachlor, endrin, and Strobane (0.28, 0.30 

 and 2.8 lbs./ac) were satisfactory. 



1956 - Pfrimmer, T. R., and R. C. Gaines. Field tests with new materials against cot- 

 ton insects at Tallulah, Louisiana during 1955. J. Econ. Ent. 49(5):712-71 3. 



In spray plots, Bayer 17147 had a significantly lower weevil infestation than 

 chlorthion, Bayer L 13/59, Strobane, and toxaphene. Strobane and toxaphene had 

 significantly higher yields. 



Bayer 17147 (2.5% and 5%) gave significantly better boll weevil control in a 

 series of dust treatments. Endrin plus sulfur and endrin alone gave significantly 

 better control than DDVP, DDVP plus Aroclor (a chlorinated polyphenyl), or 

 Bayer L 13/59 at 2 strengths. The last 4 dust treatments did not differ from the 

 check. All insecticides except endrin alone held the spider mite population sig- 

 nificantly lower than the check. 



69 



