Control of San Jose Scale With Lubricating Oil. 9 



WEAK DOSAGES OF LUBRICATING-OIL EMULSION. 



The success attained with a 1 per cent and a 14: per cent emulsion, 

 Plats 1 and 2 of Table 2, suggested the possibility that weaker 

 dosages than the 2 per cent emulsion might be effective against the 

 scale in the dormant season. Tests with three brands of oil, each 

 with dilutions of f per cent, 1 per cent, and 1^ per cent, were made 

 in the Pickens orchard at Bentonville on February 11. Conditions 

 pertaining to degree of scale infestation and spraying equipment 

 were similar to those outlined in the preceding experiment. Table 

 3 gives the results from the use of weakened oil-emulsion sprays. 



Table S.—Mortalitij of Jiihcruating San Jose scales from spraying with iveak 

 dosages of luhricating-oil emulsions, R. 0. Pickens orchard, Bentonville, 

 Ark., 



Plat. 



Insecticide. 



Dosage. 



Date of 

 applica- 

 tion. 



Date of 



examinar 



tion. 



Num- 

 ber of 

 scales 

 dead. 



Num- 

 ber of 

 scales 

 aUve. 



Percent 



of scales 



dead. 



1 

 2 

 3 

 4 

 5 

 6 

 7 

 8 

 9 



No. 4 lubricating-oil 

 emulsion. 



No. 1 lubricating-oU 

 emulsion. 



No. 2 lubricating-oil 

 emulsion. 



fU gallons in 100; | per cent. . 

 -^U gallons in 100; 1 per cent. . 

 [2i gallons in 100; IJ per cent. 



1 J gallons in 100; f per cent. . 

 hh gallons in 100; 1 per cent. . 

 [2i gallons in 100; IJ per cent. 



1 J gallons in 100; f per cent. . 

 •^U gallons in 100; 1 per cent. . 

 [2i gallons in 100; 1^ per cent. 



1922 

 Feb. 11 



1922 

 Mar. 22 

 22 

 23 



i 



25 

 25 

 25 

 25 



1,000 

 1,000 

 1,675 

 1,046 

 1,075 

 1,625 

 1,000 

 1,000 

 1,550 



20 

 18 



2 

 20 

 24 



4 

 35 

 19 



6 



P.ct. 



98.04 

 98.23 

 99.88 

 98.12 

 97.82 

 99.75 

 96.62 

 98.14 

 99.61 



The three- fourths per cent emulsion of the three different oils 

 apparently gave a fair kill of scales. The 1 per cent emulsions were 

 practically no better than the slightly " weaker three-fourths per cent 

 emulsions. The 1^ per cent emulsions in all cases killed over 99 per 

 cent of scales. It was evident from this experiment that a 2 per 

 cent emulsion was not the minimum dosage at which a good kill of 

 scales might be effected. For practical purposes, however, it is likely 

 that the 2 per cent emulsion is the lowest dosage that could be used 

 by growers to insure a successful control of the scale. 



USE OF OIL EMULSION FOR DORMANT SPRAY IN COMMERCIAL 



ORCHARDS. 



Soon after it became evident that lubricating-oil emulsion was 

 giving good control of the San Jose scale in an experimental way 

 during the dormant season, it was decided that the growers should 

 be informed of the data already at hand. Accordingly, all the 

 details of the experimental work that had been carried on were given 

 to growers in the vicinity of Bentonville. Although the investiga- 

 tion was far from complete, many growers were interested to get any 

 new suggestions on scale control. Nothing was known about the 

 possibility of injury to trees following an application of this emul- 

 sion. With the knowledge that much information covering this 

 subject was still lacking, a large number of growers voluntaril}^ 

 decided to use the emulsion for the spring dormant treatment. 



A plant for the manufacture of oil emulsion was set up at Benton- 

 ville, and growers were first supplied with the product early in 

 30836°— 23 2 



