weevil but gave good to excellent aphid control throughout the complete growing 

 period of the plant. There was no evidence that thimet was taken up or trans- 

 located more readily in soils with a lower level of phosphorus. Seed treatments 

 of thimet and Bayer 19639 adversely affected stands. In-furrow treatments of 

 thimet did not affect stands. None of the treatments affected plant height. Only 

 one treatment, the thimet Z-pound in-furrow treatment, adversely affected fruit- 

 ing. The treatments had no adverse effect on grade and staple or on the germi- 

 nation of seed produced with these treatments. Likewise, such properties as 

 fiber strength, maturity, fineness, boll size, seed index, lint index, and percent 

 of lint were not affected by any of the treatments. 



1958 - Lloyd, E. P., R. E. Furr, and M. E. Merkl. Seasonal variation in susceptibility 

 of boll weevils to insecticides. Assoc. So. Agr. Workers Proc. 55:121. 



Results of topical application tests in the fall of 1956 and the spring of 1957 

 indicated seasonal differences in susceptibility of the boll weevil to insecticides. 

 LD50 values obtained with aldrin, BHC, endrin, toxaphene, heptachlor, Thiodan, 

 malathion, methyl parathion, Guthion, and Phosdrin for weevils from the hill and 

 delta sections of Mississippi are presented. 



1958 - Mistric, W. J., Jr., and R. T. Gast. Susceptibility of the boll weevil to toxaphene 

 in North Carolina. J. Econ. Ent. 5 1 ( 5) :7 1 9-721 . 



Results of laboratory tests showed that susceptibility of the boll weevil to 

 toxaphene was related to the previous field usage of chlorinated hydrocarbon in- 

 secticides for weevil control. Weevils from fields subjected to intensive insec- 

 ticidal treatment were much less susceptible than those from nearby fields where 

 little insecticide had been used. The greatest difference in the susceptibility of 

 weevil populations from different counties was 200-fold, while the greatest dif- 

 ference within a county was 75-fold. 



A field test, conducted on the weevil population least susceptible to toxaphene, 

 showed that Guthion, malathion, methyl parathion, and calcium arsenate were 

 superior to toxaphene in weevil control and yield of cotton. However, complete 

 failure to toxaphene to control this weevil population was not experienced. 



1958 - Pfrimmer, T. R. Insecticide tests against the boll weevil and the bollworm at 

 Tallulah, La., in 1956. J. Econ. Ent. 51(l):41-43. 



In small-plot experiments with several insecticides applied as dusts and 

 sprays for the control of the boll weevil and the bollworm (Heliothis zea Boddie) 

 conducted at Tallulah, La. during 1956, Guthion gave excellent boll weevil control in 

 all tests at dosages from 0.25 to 0.6 lb. per acre. Calcium arsenate dust, 

 methyl parathion at 0.5 and 0.67 lb., EPN at 0.5 and 0.8 lb., and malathion at 2.05 

 and 3.81 lbs. per acre were slightly less effective. Methyl parathion at 0.40 lb., 

 Dipterex and Dow ET-15 at 0.5 lb., and calcium arsenate spray at 12.9 lbs. per 

 acre gave only fair control. DDT was included in most of these treatments. In 

 one experiment, endrin spray at 0.3 lb. gave fair control, but endrin dust at 

 0.37 lb. per acre was ineffective. In other experiments endrin, Thiodan, and 

 heptachlor were ineffective at the dosages used. 



1958 - Pfrimmer, T. R., and M. E. Merkl. Dosage-interval tests with phosphate insec- 

 ticides on cotton insects at Stoneville, Mississippi. Assoc. So. Agr. Workers 

 Proc. 55:121. 



During the cotton- growing season of 1957, three small plot field tests were 

 conducted against cotton insects. Various dosages (lb./ac.) of Guthion (0.25- 

 0.75), methyl parathion (0.25-0.50), and malathion (0.5-2.0) are compared at dif- 

 ferent intervals of treatment ranging from 3 to 1 days. Results against the 

 boll weevil, bollworm, aphids, and spider mites are given. 



1958 - Pfrimmer, T. R., E. P. Lloyd, and M. E. Merkl. Field tests with new insec- 

 ticides against cotton insects at Stoneville, Mississippi. Assoc. So. Agr. Workers 

 Proc. 55:121. 



Several new insecticides and insecticide combinations were tested in small- 

 plot field experiments against cotton insects during 1957. These materials 



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