seen in such infestations after they reach 10% of the cotton crop. The results of 

 experiments in 1927 indicate that when an infestation as high as 5% exists at the 

 time calcium arsenate dusting is started, a heavy aphid infestation may be ex- 

 pected after 4 applications are made. 



1928 - Grossman, E. F„ How the boll weevil ingests poison. Fla. Agr. Expt. Sta. B. 

 192:147-172, 6 fig., 18 ref. Jan. Gainesville. 



A detailed account of experiments on the poisoning of the cotton boll weevil 

 with calcium arsenate, many of the results of which have already been noticed. 

 Plots treated with a mixture of equal quantities of calcium arsenate and hydrated 

 lime yielded as much seed cotton to the acre for 3 consecutive years as those 

 treated with undiluted calcium arsenate. 



The weevil has not been controlled by taking advantage of its chemotropic, 

 phototropic, or death-feigning activities. A characteristic dipping of the snout 

 brings the mouth parts of the weevil in contact with surfaces over which it is 

 crawling. There is no indication that the H2O drinking habit of weevils is an 

 important factor for successful distribution of calcium arsenate since there is 

 no appreciable difference in mortality among weevils exposed to either wet or 

 dry poisoned plants. Use of syrup mixtures for spraying is not recommended, 

 but are useful for mopping on small cotton plants. 



1928 - Robinson, J. M. Entomology- -thirty-seventh and thirty-eighth annual reports. 

 Ala. Agr. Expt. Sta., 1925-1926:21-22 and 23-24. Auburn. 



Studies on the control of the cotton boll weevil with calcium arsenate dust. 

 On heavy red clay soil two series of plots were used, one on old ground and the 

 other on newly cleared ground. Five applications of dust were made. One was 

 washed off within 24 hours, and the fifth, according to the infestation record, was 

 unnecessary. The gains were 90 lbs. of seed cotton on the old ground and 150 lbs. 

 on the newly cleared area, but these were not sufficient to make dusting profit- 

 able. On "black belt" clay, 9 applications of dust were made throughout the season, 

 3 of which were washed off within 25 hours. The gain was 300 lbs. of seed cotton 

 per acre on the dusted plots. On sandy loam plots the tests were carried out to 

 determine the effect of dusting on plots of cotton fertilization up to 1,500 lbs. per 

 acre on both dusted and undusted plots. Weevil infestation reached 13% on August 

 27. Three applications of calcium arsenate were made at intervals of 5 days. The 

 gain due to dusting varied from minus 12 lbs. of seed cotton on the unfertilized 

 plots to 204 lbs. on the plot receiving 500 lbs. of fertilizer and 420 lbs. on the 

 plot receiving 1,500 lbs. of fertilizer. The average results for the three years 

 of the experiment show that the increase in yield from dusting has been de- 

 pendent on the rate of fertilization, and that poisoning for weevil control is not 

 profitable unless other conditions are favorable for the production of a good 

 crop. 



1928 - Walker, H. W. The preparation of a special light sodium fluosilicate and its use 

 as a boll weevil poison. J. Econ. Ent. 21(1): 156-164. 



Two serious objections to the use of commercial sodium fluosilicate as a 

 poison for the boll weevil are its lack of covering power, due to its comparatively 

 high apparent specific gravity, and its toxicity to plants. These have been over- 

 come by incorporating from 10% to 20% colloidal silica with sodium fluosilicate 

 during the commercial process of manufacture. 



The resulting special light sodium fluosilicate, containing at least 80% 

 Na2SiF^, causes no economic plant injury and is a quicker weevil killer than 

 commercial calcium arsenate. Under certain field conditions, however, it does 

 not adhere to the plant so well as calcium arsenate. This lack of adherence under 

 extremely moist conditions can probably be overcome by the incorporation of a 

 small amount of adhesive during the process of manufacture. 



Barium fluosilicate similarly prepared is about as effective as the sodium 

 salt. 



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