

Control of San Jose Scale With Lubricating Oil. 7 



Table 1. — Mortality of hiherimting San Jose scales from spraying ivitJi ail emul- 



sions, lime-su Ipli u >:, 

 Ark., 1921-22. 



and a misclMe oil, Engli^sJi d Boles orchard , Bentonville, 



Plat. 



Insecticide. 



Dosage. 



Date of • Date of 

 applica- examina- 



Num- 

 ber of 

 scales 

 dead. 



be^f Pe^^^t 

 scales «f^«^d 



No. 1 oil einialsion . 



....do 



....do 



....do 



No. 2 oil emulsion . 



....do 



....do 



Kerosene emulsion 



do 



No. 1 commercial lime- 

 sulphur. 



No. 2 commercial lime- 

 sulphur. 



No. 3 'Commercial lime- 

 sulphur . 



Homemade lime-sulphur. 



Miscible oil 



Check (unsprayed) 



3 gallons in 100: 2 per cent 

 6 gallons in 100; 4 per cent 

 9 gallons in 100: 6 per cent 

 12 gallons in 100; 8 per 



cent. 

 6 gallons in 100; 4per cent 

 9 gallons in 100: 6per cent 

 12 gallons in 100; S per 



cent. 



20 per cent 



25 per cent 



32°B., 6|gaUonsin50-.. 



do 



29° B., 10 gallons in 50... 



29° B., 9 gallons in 50.... 

 3g gallons in 50 



1921 



Dee. 14 



14 



14 



14 



14 

 14 

 14 



14 

 14 

 16 



1922 



Jan. 11 



11 



11 



11 



11 

 11 

 11 



19 

 19 

 IS 



Feb. 



5 

 Jan. 11 



3,400 

 1,100 

 1,000 

 1,000 



1,000 

 1,000 

 1,000 



1,040 



1,012 



830 



803 



1,015 



1,012 



1,200 



221 



3 

 2 

 

 





 

 



35 



17 



207 



224 



125 



225 

 29 

 802 



P.ct. 

 99.91 

 99.82 



100 



100 



100 

 100 

 100 



96.74 

 98.35 

 80.04 



78.19 



89.03 



81.81 

 97.64 

 21.60 



It will be noted that Plats 1 to T, inclusive, comprising tests with 

 various strengths of two different brands of lubricating oil, gave 

 ver}^ encouraging results. When it was found that Plat 1, a 2 per 

 cent lubricating-oil emulsion, was showing good killing, a large 

 number of scales were examined to get an approximate estimate of 

 the efficiency of this low-strength oil emulsion. Examination of a 

 large number of scales in the higher-strength oil-emulsion tests was 

 deemed unnecessary. 



Plats 8 and 9, spra^^ed with a 20 per cent and 25 per cent kerosene 

 emulsion, respectively, gave a fair kill of scales. Trees in these two 

 plats looked oily for a period of perhaps 10 daj^s or 2 weeks after 

 the spray application, whereas trees in Plats 1 to 7, inclusive, had 

 a very oih" appearance for more than a month following the spray. 

 Likewise the scale insects of the kerosene-emulsion plats, either dead 

 or alive, showed no trace of oilinesson the date of examination, while 

 the scales of the lubricating-oil emulsion plats still retained a thin 

 oil film 30 days after thej- were spraj^ed. Apparenth^ high dosages 

 of kerosene emulsion with their corresponding high volatility were 

 less effective at this time of year against the San Jose scale than the 

 low-strength lubricating-oil emulsions with their low percentage of 

 volatility. 



Plats 20 and 21, sprayed with two different brands of commercial 

 lime- sulphur, gave about equal kill. The concentrated lime-sulphurs 

 used in Plats 22 and 23 tested so low that they were applied extra 

 strong. All lime-sulphur plats, at the time of examination, showed 

 poorer results than the oil-emulsion plats. 



Plat 25, sprayed with a proprietar}" miscible oil, gave about the 

 same Irili of scales as the kerosene emulsions. This oil, like the 

 kerosene emulsions, was far more volatile on the trees than the 

 heavier grade lubricating-oil emulsions. 



Under Plat 26 the percentage of dead scales on twigs of unsprayed 

 trees is given. 



