1928 - Walker, H. W. The preparation of special calcium arsenates containing less than 



40% arsenic as AS2O5 and their use as boll weevil poisons. J. Econ. Ent. 

 21(1): 165- 173. 



A special calcium arsenate containing only about 20% arsenic calculated as 

 AS2O5 was equally as effective as a control for the boll weevil as commercial 

 calcium arsenate in extended cage and field tests. The material caused no plant 

 injury. 



This special calcium arsenate was prepared by heating precipitated chalk 

 and white arsenic (AS2O3) in the presence of excess air at a temperature of 650° 

 C. (1202° F.) for about one hour. In this manner it was possible to prepare a cal- 

 cium arsenate containing any desired percentage of arsenic as AS2O5 up to 57.6%, 

 the theoretical for normal calcium arsenate Ca3(As04)2. The conversion from 

 the trivalent to the pentavalent state is practically complete, and there is scarcely 

 any free lime formed under these conditions. Any arsenic lost in this process is 

 recoverable on a commercial scale. 



The particles of the special calcium arsenate containing 20% arsenic as 

 AS2O5 consisted of an inert core of calcium carbonate covered with a coating of 

 substantially 100% normal calcium arsenate. 



This direct oxidation method of preparation is adaptable for arsenates other 

 than calcium, 



1929 - Bishopp, F. C. The bollworm or corn ear worm as a cotton pest. U. S. D. A. 



Farmers' B. 1595, 14 p., 12 fig., 7 ref. June. Wash. 



"Where the cotton boll weevil (Anthonomus grandis) and H. obseleta occur 

 together, dusting with calcium arsenate is effective against both. Paris green 

 can be applied as a spray (1 lb. to 50 U.S. gals, water) or as a dust (1 lb. to 3 lbs. 

 air-slacked lime), but it is liable to scorch the foliage. Lead arsenic is less 

 toxic, and more expensive than calcium arsenate. Dusting should be carried out 

 at night when the plants are covered with dew, and 2 applications at an interval of 

 7-10 days usually give satisfactory results. The intensity of infestation varies 

 from year to year, and the actual number of applications should depend upon the 

 abundance of eggs deposited after the first application." 



An account is given of the use of maize as a trap-crop for protecting cotton, 

 and it is pointed out that the former should be planted late enough to attract the 

 moths when they are ovipositing. The moths then concentrate on the maize from 

 considerable distances, and the larvae are so numerous that they destroy each 

 other and only a few of the many individuals hatching on the silk of each ear 

 reach maturity. 



1929 - Coad, B. R., and R. C. Gaines. Poisoning the cotton boll weevil. U. S. D. A. 

 Leaflet 37, 4 p. Apr. Wash. 



Brief popular instructions for the application of calcium arsenate dust 

 against the cotton boll weevil in the cotton belt of the United States. 



1929 - Grossman, E. F. Diluted calcium arsenate for boll weevil control. J. Econ. Ent. 

 22(6):972-974. 



Additional experiments conducted in 1928, in the control of the cotton boll 

 weevil, with equal quantitites of calcium arsenate and hydrated lime, confirm a 

 series of tests carried out during 1924-26. The four years' results are shown in 

 a table. The average yield from plots of cotton dusted with diluted and undiluted 

 calcium arsenate was about identical throughout, and, in view of the reduced cost 

 of treatment with the diluted mixture and the fact that no mechanical difficulty is 

 attached to its preparation, it is recommended for use. 



1929 - Robinson, J. M., and F. S. Arant. Dusting cotton with calcium arsenate for boll 

 weevil control. Ala. Agr. Expt. Sta. C. 53. May. 



Average increase from dusting ranges from 258 to 312 lbs. of seed cotton 

 per acre. Forty lbs. of calcium arsenate was the average needed for each acre 

 per season. Dusting operation cost was $5 per acre. Control is profitable only 

 when infestation exceeds 10% and when potential yield is 1/2 bale or more per 

 acre. Treatments were successful on either wet or dry foliage. 



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