199 



lessened its adhesive properties, this decrease in adhesiveness being 

 greater in some brands than in others. Molasses was found also 

 greatly to decrease the adhesiveness of a commercial preparation of 

 Bordeaux mixture and lead arsenate. As cane sugar, used in prac- 

 tically the same amount as is contained in molasses, caused marked 

 lack of adhesiveness in lead arsenate, it is believed that the sugar in 

 the molasses is largely responsible for the decreased power of adhesion. 

 Working upon these indications it was found possible to secm'e 

 excellent results with molasses and lead arsenate in the control of 

 F. viticida by studying the weather and applying the spray when there 

 was little probability of rain for three or four days, and also by f ollo^^^ng 

 the first spraying in about a week with an application of Bordeaux 

 mixture and lead arsenate to act as a repellent to invading beetles 

 that might enter the vineyard during the dispersion period. 



LovETT (A. L.). Spreaders for Arsenate Sprays. — Jl. Econ. Entom., 

 Concord, N.H., xi, no. 1, February 1918, pp. 66-69. 



The problem of economy has made necessary a very intensive 

 study of spray materials at Oregon, where the mild climate, excessive 

 moisture conditions in the spring, and the narrow margin of profit, 

 require a very high percentage of perfect fruit if the crop is to produce 

 any return. The investigations of the past three seasons have led to 

 the conclusion that lead arsenates have hitherto been used in a more 

 concentrated form than is necessary [see this Review, Ser. A, iii, p. 759 

 and v, p. 477]. Laboratory experiments indicate that approximately 

 as great efficiency is obtained ^^^th acid lead arsenate at a dilution of 

 1:400 as at 2:50. Growers however prefer the additional expense of 

 using 3^ lb. to 50 gallons as a protection against codling moth {Cijdia 

 pomoneUa) in the July and August applications, but it is believed that 

 if a satisfactory spreader can be developed it will be possible to acquire 

 very effective control of this pest vnth a diluted spray composed of 1 lb. 

 arsenate to 100 gals, solution. By an efficient spreader is meant 

 some material that allows the droplets to spread out and join one 

 . another as they dry so that the arsenate remains as an even, regular, 

 inconspicuous covering affording perfect and equal protection for 

 every surface. 



The surface tension and specific gravity are probably important 

 factors in determining the value of a spreader, but the correlation of 

 each to the other has not been determined and does not appear to be 

 in a direct proportion. The ability of a liquid to hold arsenate in 

 suspension does, however, appear to be a very fair indication of its 

 utility as a spreader. The materials tested were sage tea, glue, 

 glycerine, gelatine, sugar, honey, gum tragacanth, fish- oil soap, 

 casein-Hme and resin soap. The results of these suspension tests 

 are shown in .a table. Sugar precipitated the arsenate, while gum 

 tragacanth did not go into solution. A test of the solutions w^as 

 then made on bean foliage. The two materials that produced the 

 least scorching weve sage tea (5 : 1000) and the casein-lime mixture 

 (5 : 1000), and these also approximated to the ideal qualifications for 

 a spreader. Tested on strawberry foliage they gave equally satisfac- 

 tory results. 



