produced significantly higher yields than a plot sprayed with heptachlor-DDT. In 

 the same experiment there was no significant difference in yield when dieldrin 

 was applied as a dust and as a spray. 



In one small-plot and one large-scale experiment, toxaphene dust gave bet- 

 ter boll weevil control and higher increases in yield than sprays containing toxa- 

 phene, benzene hexachloride plus DDT, aldrin plus DDT, or dieldrin. Dieldrin 

 applied as a boll weevil dosage did not give satisfactory control. Toxaphene was 

 more effective against bollworms when applied as a dust than as a spray. In 4 

 large-scale experiments a 0.375-pound dosage of aldrin gave better boll weevil 

 control and higher increases in yield than a 0.25-pound dosage. In a large-scale 

 experiment with 3 replications of each treatment, aldrin-DDT spray applied by an 

 airplane at the rate of 0.375 pound of each insecticide per acre gave significantly 

 better boll weevil control and a significantly higher yield than a toxaphene spray 

 applied at 3 pounds per acre. 



1953 - Rainwater, C. F., E. W. Dunnam, E. E. Ivy, and A. L. Scales. Calcium carbonate 

 as a diluent for insecticide dusts. J. Econ. Ent. 46(6) :923-927. 



Biological tests were conducted to determine the stability of insecticide dusts 

 formulated with calcium carbonate as the diluent. 



The calcium carbonate used was ground limestone that had been treated with 

 a chemical reagent to produce a free -flowing, nonwettable powder. The dusts were 

 held in storage in glass bottles at room temperature or in paper bags at 100% 

 relative humidity, and tested at intervals for a year or more. Dusts of the same 

 insecticides formulated with pyrophyllite were tested for comparison. 



The only evidence of breakdown or loss in effectiveness occurred sometime 

 between 6 and 14 weeks after the BHC -calcium carbonate dust had been held in 

 paper bags at 100% relative humidity. After a slight loss, however, the mixture 

 apparently remained stable during the rest of the 66 weeks in storage. 



These tests indicate that the insecticides will remain stable when formulated 

 in dusts with a free-flowing, nonwettable form of calcium carbonate and held 

 under ordinary dry storage conditions for a year or more. 



Dusting quality of formulations prepared with the special calcium carbonate 

 was greatly improved over that of regular commercial dusts for application by 

 ground machines and airplane. 



In field tests, dusts containing 20% of toxaphene, and sufficient BHC to give 

 3% of the gamma isomer plus 5% of DDT formulated with this special calcium 

 carbonate, gave just as good control of the boll weevil and the bollworm as the 

 same toxicants, and others, prepared with commercial diluents. 



1953 - Scales, A. L,., E. E. Ivy, J. C. Gaines, and C. F. Rainwater. EPN for cotton in- 

 sect control. J. Econ. Ent. 46(1): 1 30-133. 



The fact that EPN exhibited comparatively high toxic action against the boll 

 weevil in field and greenhouse tests makes it a promising insecticide for use 

 against cotton insects, and large-scale field experiments with it appear to be 

 justified. The dosage indicated for boll weevil control, comparable to that ob- 

 tained with 2 pounds of technical toxaphene or 10 pounds of calcium arsenate, is 

 0.3 pounds of technical EPN per acre. This dosage probably would also be very 

 effective against the cotton leafworm. 



The data indicate that, when used for boll weevil control at 0.3 pound per 

 acre, EPN would give very good control of spider mites on cotton. Although this 

 dosage was not highly effective against the cotton aphid, the data showed that 

 mortality in excess of 50% might be expected. This degree of control might be 

 expected to hold the cotton aphid in check, since that aphid is seldom a problem 

 unless insecticides relatively ineffective against it are used to control other 

 insects. 



A serious drawback to the indicated use of EPN for control of cotton insects 

 was its failure to control the bollworm at the dosage indicated as effective. Be- 

 fore EPN could compete with the insecticides recommended for overall control of 

 cotton insects, it would almost certainly be necessary to add DDT to the dusts or 

 sprays in such proportion that a minimum of 0.5 pound per acre of technical DDT 

 would be applied. 



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