737 



Scott (E. W.) & Siegler (E. H.). Miscellaneous insecticide investi- 

 gations.— Z7. >S. Dejit. Agric, Wnshington, B.C., Bull. no. 278, 

 Sth October 1915, 47 pp. 



Numerous experiments made with miscellaneous insecticides and 

 spray combinations during 1912, 1913 and 1914 are described in a 

 series of tables. Lead arsenate proved to be the most consistent and 

 valuable stomach poison tested and was equally effective in either the 

 paste or the powder form. Triplumbic arsenate of lead is less rapid 

 in its effects than diplumbic arsenate, but is safer for use on tender 

 foliage. Lead arsenate may be combined with nicotine solutions and 

 lime-sulphur solution for the control of certain apple chewing and 

 sucking insects, and fungus diseases. For the control of other sucking 

 and chewing insects, lead arsenate may be combhied with kerosene 

 emulsions. Arsenate of lead, kerosene emulsion, and lime-sulphur 

 is an incompatible mixture, owing to the formation of an insoluble 

 calcium soap and the subsequent release of free kerosene. This result 

 occurs in any combination containing lime-sulphur and soap. Lead 

 arsenate should not be mixed with sodium sulphide compounds, as 

 the soluble sodium arsenate formed is destructive to leaf tissue. Lead 

 arsenate combined with a commercial ba-rium tetrasulphide gave 

 satisfactory control of the codling moth [Cydia po7)ioneUa] and caused 

 no foliage injury in the experimental apple orchard. The most 

 promising new insecticide is arsenate of calcium, which may be readily 

 prepared as follows : — Stone lime (90 per cent. CaO), 55 lb. ; sodium 

 arsenate, fused (dry, powdered) 65 per cent. As.^O.;, 1001b. ; water, 

 26 U.S. gals. The stone lime is placed in a wooden container and a 

 small amount of water added, just enough to start slaking. When 

 slaking is well under way, the sodium arsenate, which should first 

 have been dissolved in hot water, is poured in and the mixture kept 

 stirred until the lime has thoroughly slaked. Sufficient water should 

 be added from time to time to prevent burning. The resulting arsenate 

 of calcium should contain about 18 per cent, of arsenic oxide. In 

 making this compound, it will be necessary to know approximately 

 the calcium oxide and arsenic oxide content of the materials and to vary 

 the formula accordingly. At the present time, arsenic acid cannot 

 be obtained at a reasonable price and the fused (dry, powdered) 

 sodium arsenate is recommended in the formula. While arsenate of 

 calcium may have certain limitations, it will doubtless prove of value 

 for the control of chewing insects on certain crops. Ai-senate of iron 

 and arsenate of zinc ajre not so satisfactory as lead arsenate. Arsenites 

 are dangerous to use on tender foliage. In some instances, however, 

 it may be possible to prevent foliage injury to some extent by combining 

 the soluble arsenic with lime. Sodium-sulphur and potassium- 

 sulphur compounds gave fairly satisfactory control of the San Jose 

 scale [Aspidiotus 2)erniciosus], in some instances equalling lime-sulphur 

 solution. They may readily be prepared at home without the use of 

 heat. In this bulletin, reference to any given insecticide or com- 

 bination spray is rendered easy by means of a list arranged in 

 alphabetical order. 



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