Control of San Jose Scale With Lubricating Oil. 17 



the steam pump into the third tank to complete the second pumping. 

 From this third tank the finished emulsion is drawn off in barrels. 



SOAPS AND OILS. 



The best soap for emulsifying the mixture is potash fish-oil soap. 

 W. W. Yothers, in his experience of more than 10 years with oil 

 emulsions used to control scales on citrus trees in Florida, has found 

 that potash fish-oil soap gives the most satisfactory emulsion. 



The oils that have given good results in Arkansas are the " red 

 engine" oils suitable for use in stationary gas engines. Practically 

 all oil companies handle oils of this type. No oils of lighter grade 

 than these have been used. 



Analyses of several oil samples have been furnished by the Bureau 

 of Chemistry of the United States Department of Agriculture. The 

 analysis of the oil which was most widely used commercially 

 follows : 



Appearance : Red. 



A.sh per cent__ 0. 028 



Volatility (loss at 105-110° C. after 4 hours) do 0.01 



Flash-point (Pensky-Martin apparatus) °C— 186 



Fire-point (Pensky-Martin apparatus with open cup) do 236 



Viscosity (Engler number, water=l) at 20° C_— 17. Tl 



Specific gravity at 20° C. (Westphal) 0.894 



Reaction to litmus : Neutral. 



RECOMMENDATIONS. 



The San Jose scale can be controlled in the Ozark region of Ar- 

 kansas by a spray application in the dormant season with a so-called 

 paraffin-oil or lubricating-oil emulsion. Thorough spraying with an 

 emulsion containing 2 per cent of oil should clean up bad infesta- 

 tions of the scale. The application may be made at any time during 

 the dormant season when the weather is fit for spraying. It is ad- 

 visable to make two dormant sprays in orchards that are incrusted 

 with the scale. No indication of injury to trees from the use of 

 lubricating-oil emulsion as a dormant spray has been observed 

 following its use for one season in commercial orchards of Arkansas. 



Soft water should be used with the stock emulsion for spraying 

 whenever possible. Hard water in many instances will set free 

 some of the oil in the emulsion. Lime-sulphur residue in the spray 

 tank or spray pump Avill also produce some free oil. The sprayer 

 should be thoroughly cleaned with a caustic soda solution before 

 oil emulsion is used. If hard water must be used for spraying, a 

 weakened Bordeaux, at the rate of J-J-50, can be added. This 

 will make the hard waters of the Ozarks mix with the stock emulsion. 

 Care should be taken to protect the stock emulsion from freezing, 

 which occurs when it is exposed to temperatures of about 15° F. 



The time to control the San Jose scale is during the dormant 

 season. Summer treatments with lubricating-oil emulsion and with 

 other insecticides have failed to clean up severe infestations of 

 scale satisfactorily. The best results that can be hoped for with 

 summer sprays of oil emulsion are a partial checking of the scale. 



