increases in yield. Spider mites increased enough to require control measures 

 in the endrin-DDT plots. 



Series 2. High infestations of both pink bollworms and boll weevils developed 

 in this experiment. Very good control of both insects was obtained from 5% 

 Guthion applied as a dust at approximately weekly intervals. The increase in 

 seed cotton yield was outstanding--2034 pounds. 



TESTS IN 1 956. --Series 1. This group consisted of a comparison of Guthion 

 plus DDT and Phosdrin plus DDT applied as sprays. Guthion noticeably reduced 

 the boll weevil populations, whereas Phosdrin failed to give any appreciable 

 control. Increases in yield over the untreated plot ranged from 510 lbs. 

 (Phosdrin- DDT) to 1,030 lbs. (Guthion- DDT). 



Series 2. This series was composed of only 1 spray test with 3 0.5-acre 

 replicates of Guthion plus DDT and endrin plus DDT. The last 2 applications 

 were made with 2% endrin dust and 3% Guthion dust, since the plots were too wet 

 for operation of the sprayer. 



Both the endrin and the Guthion gave effective control of the boll weevil. The 

 best yield increase was obtained from the endrin-DDT (976 lbs. seed cotton per 

 acre), as compared to 643 lbs. from the Guthion- DDT plots. 



Series 3. This dust series consisted of 2 tests with 3 0.25-acre replicates 

 of Guthion plus DDT and Guthion alone. Both the pink bollworm and the boll 

 weevil were important in this series, especially in one of the tests. Three 

 percent Guthion was effective against the boll weevil. Yield increases were good 

 for each treatment-- 1 ,284 lbs. and 1,270 lbs. respectively. 



Series 4. This was a dust series and consisted of 1 test with 3 0.25-acre 

 replications of endrin plus sulfur, and calcium arsenate. An unusually heavy boll 

 weevil infestation occurred during the entire poisoning program. Satisfactory 

 control of the populations was obtained from the endrin plus sulfur, whereas the 

 results from the calcium arsenate were not as good as expected. Yield increases 

 were 1,860 lbs. from the endrin plus sulfur applications and 1,310 lbs. from the 

 calcium arsenate ones. 



1957 - Merkl, M. E., and R. E. Furr. Experiments on control of early season cotton in- 

 sects with systemic insecticides. Assoc. So. Agr. Workers Proc. 54:145. 



Results of field tests for control of early- season cotton insects with sys- 

 temics. Thimet and Bayer 19639 were used in these experiments at dosages of 

 0.1 to 3.0 pounds per acre. Treatments were applied to cotton seeds or directly 

 to the furrow in which the seeds were planted. 



There was no indication of control of overwintered boll weevils by these 

 treatments. 



1957 - Parencia, C. R., Jr., J. W. Davis, and C. B. Cowan. Control of early-season 



cotton insects with systemic insecticides employed as seed treatments. J. Econ. 

 Ent. 50(l):31-36. 



The effectiveness of Am. Cyanamid 12009, 12008, and 3911 employed as 

 seed treatments against thrips ( Frankliniella sp.), cotton aphid ( Aphis gossypii 

 Glov.), serpentine leaf miner ( Liriomyza pusilla (Meig.)), cotton fleahopper 

 ( Psallus seriatus (Reut.)), and the overwintered boll weevil ( Anthonomus grandis 

 Boh.), was evaluated in field experiments conducted near Waco, Tex., in 1954 and 

 1955. 



In 1954, plant emergence was reduced by 39% by the 12009 and 13% by the 

 12008 treatments. The planting rate was less than desired, and the compounds 

 were applied at slightly more than 1/2 pound per acre. 



In most of the 1955 experiments, the treated seed was planted under good 

 germinating conditions and 1 lb. per acre dosages of 3911 and 12008 did not 

 adversely affect plant emergence. Emergence was reduced in a planting of 

 3911-treated seed following a heavy rain on the day after planting. 



When adult cotton fleahoppers and overwintered boll weevils were installed 

 at weekly intervals after plant emergence on caged plants in the 1 lb. 3911 seed 

 treatment, there was a progressive loss in effectiveness with plant growth. Field 



73 



