field tests the average increase in yield for low calcium arsenate was 3.8 lbs. 

 per plot, or 20.3%; for intermediate, 3.0 lbs., or 16.0%; and for high, 3.1 lbs., or 

 16.6%. The author's conclusions are that there was no significant difference be- 

 tween calcium arsenates containing low, intermediate, and high percentages of 

 water soluble arsenic pentoxide. 



1939 - Gilmer, Paul M. Control of the boll weevil on sea-island cotton. J. Econ. Ent. 

 32(6):802-805. 



Sea-island cotton was heavily infested and severely damaged by the boll 

 weevil in 1938. In experiments conducted at Tifton, Georgia, the following insec- 

 ticidal treatments were tested against the weevil: Calcium arsenate applied at 

 the rate of 6.5 lbs. per acre per application when 5% of the squares were infested 

 (intensive dust series); calcium arsenate applied at the same rate when 10% of the 

 squares were infested (standard dust series); and calcium arsenate, syrup, and 

 water (5 lbs. to 1 to 40 gals.) applied at the rate of 15 to 25 gals, per acre through- 

 out the season (sprayed series). All treated plots increased in yield over the un- 

 treated check plot, the treatments being effective in the order listed. 



The dusted plots produced lint of No. 1 grade, valued at 25 £ a pound; the 

 sprayed plots, No. 2 grade, valued at 22£ a pound; and the check plot, No. 4 grade, 

 valued at 18£ a pound. 



The gains in yield and the improvement in grade from weevil control re- 

 sulted in an increased crop value, over cost of treatments, of about $10 per acre 

 in the dusted plots and about $4 in the sprayed plots. 



1939 - McGarr, R. L. Progress report on mixtures of calcium arsenate and sulfur for 

 control of the boll weevil at State College, Mississippi. J. Econ. Ent. 32(6):792- 

 794. 



"Tests were made on small (one-tenth-acre) plots dusted with a 1:2 mixture 

 of calcium arsenate and sulfur, a 1:1 mixture of calcium arsenate and sulfur, and 

 calcium arsenate alone, each replicated 12 times for control of the boll weevil. 

 The infestation records showed very little difference in the control obtained with 

 the different insecticides. While the yield records showed no significant differ- 

 ence between the insecticides, the average gains and profits were slightly in favor 

 of the mixtures over the calcium arsenate. Tests on large (two-thirds -acre) plots 

 on which a comparison was made of results from a 1:2 mixture of calcium ar- 

 senate and sulfur and from calcium arsenate alone, on early planted cotton with 

 calcium arsenate alone, on late planted cotton with heavy weevil damage in un- 

 treated plots, gave large gains and profits in both cases, with slightly better 

 results from the mixture than from the calcium arsenate." 



1939 - Rainwater, C. F. Experiments using several insecticides with and without wet- 

 ting agents and stickers for boll weevil control. J. Econ. Ent. 32(5):700-703. 



Experiments were carried out in South Carolina in 1938 in which several 

 insecticides applied as dusts, both alone and in combination with different com- 

 mercial wetting agents and adhesives, were compared with calcium arsenate dust 

 for the control of Anthonomus grandis Boh. on cotton. It was desired to find a 

 substitute for calcium arsenate, because it is thought to injure the soil, and 

 severe infestation by aphids often develops when it is applied repeatedly. 



The insecticides tested were two nicotine compounds. One contained nicotine 

 bennite and the other, nicotine bentonite plus nicotine tannate, and two cryolite 

 dusts. One was a finely ground, synthetic, cryolite containing 90.8% sodium fluo- 

 aluminate, of which 88% of the particles were less than 10 microns in diameter, 

 and the other, a coarsely ground cryolite containing 78.3% of sodium fluoalumi- 

 nate, of which 35% of the particles were more than 50 microns in diameter. A 

 mixture of calcium arsenate and calcium carbonate without an adhesive or 

 spreader was also tested. The dusting qualities of both cryolites were extremely 

 poor. 



Statistical studies of the data showed that none of the wetting agents and 

 adhesives increased the effectiveness of the calcium arsenate or the nicotine 

 compounds. A synthetic liquid adhesive and spreader (lethane) increased the 



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