72 CIRCULAR 2 70, U. S. DEPARTMENT OF AGRICULTURE 



LuBRICATING-OlL EMULSIONS 



Lubricating-oil emulsions are extensively used in the Pacific North- 

 west for controlling the San Jose scale, red spiders, and leaf rollers, 

 and are also used against the codling moth and other insects. They 

 may be purchased in a form which can be readily diluted with water, 

 or, if the grower desires to prepare his own emulsions, the following 

 formula may be used: 



Water 33 gallons. 



Ammonia (28 percent) 1 quart. 



Casein (finely powdered) 3 pounds. 



Oil 100 gallons. 



Put the water into the spray tank, and, with the pump and agitator 

 running, add the ammonia and then sift in the casein slowly. As soon 

 as the latter has dissolved, which will be almost immediately, add the 

 oil about as fast as it will run from the drum. Be sure to let the oil 

 run in at least this slowly until the agitator is well covered, or a 

 reversed emulsion may result. (A reversed emulsion will not mix 

 with water and cannot be used.) Allow the mixture to be stirred 

 thoroughly by the agitator for a few minutes and then pump it through 

 a piece of spray hose at about 250 pounds' pressure into empty drums 

 for storage until it is used. A second pumping is advisable if the 

 emulsion is to be kept more than a week or so. The emulsion should 

 not be made during freezing weather, but when once made it will stand 

 the ordinary temperatures occurring after March 1 . It should be used 

 as soon as possible after making, although it will usually keep for 

 several weeks in closed drums. The cost of making, aside from the 

 cost of the oil, should not be over 2 cents per gallon. 



The methods of preparing emulsions for dormant and summer use 

 are the same, except that different oils are needed for the two pur- 

 poses. The grower should be sure that the proper oil is employed, 

 whether he makes his own emulsions or buys the prepared material. 

 The most important specifications for oils are the viscosity, measured 

 by the rate of flow, and the unsulfonated residue, or degree of refine- 

 ment. For dormant spraying the oil should have a viscosity of 100 

 to 120 seconds Saybolt, and an unsulfonated residue of 50 to 70 per- 

 cent. For summer spraying under most conditions the viscosity of 

 the oil should be 65 to 75 seconds Saybolt (" light medium" or "me- 

 dium" oil), and the unsulfonated residue should be at least 85 percent. 

 For yellow varieties of apples, such as the Yellow Newtown, the 

 viscosity of the oil should not exceed 55 seconds (" light" oil). When 

 oil emulsion is used with lead arsenate, it should be put into the tank 

 first, and the lead arsenate added just before the tank is full. Com- 

 binations of some brands of oil emulsion and lead arsenate may cause 

 a slight burning of the foliage, or the mixture may flocculate or 

 "curd" in the tank. The latter is usually not objectionable and may 

 be advantageous in allowing more of the mixture to adhere to the fruit. 

 Combination sprays should be used immediately after being mixed. 

 If they are allowed to stand, they may undergo changes that will 

 reduce their effectiveness or increase the difficulty of removing spray 

 residues. The manufacturer's directions for mixing should always be 



