and sprays. Dusts containing 2.5%, 3.5%, and 5.0% of heptachlor were compared 

 with each other and also with dusts containing 2.5% aldrin, 1.5% of dieldrin, and 

 impregnated BHC containing 3% of the gamma isomer. No significant difference 

 in boll weevil control was obtained between concentrations of heptachlor or be- 

 tween heptachlor and any of the other insecticides. 



Emulsion sprays containing heptachlor gave boll weevil control equal to that 

 of aldrin and dieldrin and similar to that obtained with dusts in equivalent dosages. 

 Control with BHC dusts and chlordane sprays was about the same. DDT at the 

 rate of 0.5 pound per acre was included in each treatment from August 2 to Sep- 

 tember 4 for control of the bollworm. Apparently, heptachlor had very little 

 effect on infestations of the cotton aphid and spider mites. 



It is concluded from these experiments, and from other observations and 

 tests made in 1949 and 1950, that heptachlor at 0.25 pound per acre, in either dust 

 or spray, is sufficient for control of the boll weevil under the conditions existing 

 at Stoneville, Miss. 



1953 - Calhoun, S. L., and E. W. Dunnam. Endrin for control of cotton pests. J. Econ. 

 Ent. 46(1):170-172. 



Two field experiments with endrin for the control of cotton pests were 

 conducted in the vicinity of Stoneville, Miss., in 1951. In experiment 1, endrin, 

 applied at the rate of 0.2 pound per acre, was compared with a mixture of 0.2 

 pound of dieldrin plus 0.5 pound of DDT. Three gallons of emulsion per acre was 

 applied with tractor- mounted spray equipment. Endrin control of the boll weevil 

 was equal to that obtained with the dieldrin- DDT mixture, but it was slightly 

 better controlling bollworms. 



In experiment 2, endrin applied at the rate of 0.2 pound per acre was com- 

 pared with an untreated check. Applications were made with airplane-mounted 

 spray equipment at the rate of 1 gallon per acre. Endrin produced excellent 

 control of the boll weevil and bollworms, compared with an untreated check. 



1953 - Hanna, R. L., and W. J. Mistric, Jr. Effect of different treatment schedules for 

 control of cotton insects. J. Econ. Ent. 46(4):641-644. 



Replicated tests designed to evaluate the effectiveness of 1, 2, and 3 early- 

 season insecticidal applications, both on a small-plot basis and on a larger plot 

 basis, showed no significant differences in yield between the 3 treatment sched- 

 ules and the control. The large-plot test indicated a slightly earlier fruiting for 

 all plots receiving early treatment than for the control plots. Small-plot tests 

 showed that an 8-day treatment interval did not compare favorably with a 4-day 

 treatment interval under conditions of damaging boll weevil or bollworm infesta- 

 tion. 



1953 - Ivy, E. E., C. F. Rainwater, A. L. Scales, and L. J. Gorzycki. Comparative 

 effectiveness of the ethyl and methyl homologs of nine phosphorus compounds 

 against four cotton pests. J. Econ. Ent. 46(4):630-633. 



Findings supported the hypotheses made at the beginning of the study-- 

 namely, that the boll weevil is an exception to the general order of toxicity. 

 Of the ethyl and methyl homologs of 9 phosphoric acid esters, the ethyl compound 

 is usually more effective against the cotton aphid, the desert spider mite, or the 

 cotton leafworm but not against the boll weevil. Exceptions were found with each 

 species, however, and there appeared to be no consistent pattern to these excep- 

 tions, or to the variations in the relation between the dosages required for the 

 2 homologs against the different species. 



Two important facts emerge from the study. In the first place, in the de- 

 velopment of new phosphorus compounds for the control of the boll weevil, com- 

 pounds having methyl substituents should receive priority. However, in view of 

 the exceptions, in the absence of actual tests we should be very careful in making 

 too broad generalizations or assumptions concerning the specific performance 

 of any new compound. 



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