120 



J. Ease of Dilution 



The ease with which any spray material mixes in the tank is an im- 

 portant consideration. Some stock emulsions look good, but upon dilu- 

 tion with water, free oil, which may be injurious to plants, appears on 

 the surface. 



In the case of the cold-mixed emulsions with Bordeaux mixture as 

 the emulsifying agent, the stock emulsion rises to the top of the spray 

 solution, though no free oil may appear. This difficulty can be overcome 

 by diluting the stock emulsion with a weak Bordeaux instead of water. 

 A 1-1^-50 Bordeaux holds it at an equilibrium. It is possible that with 

 the agitator in a spray tank running, this difficulty would not be so 

 serious, but the stock emulsion rises quickly, and it is not at all certain 

 that with the agitator in the bottom of a full tank, a good mixture 

 could be made. 



4. Stability 



On the whole, cold-mixed emulsions are not as stable as boiled emul- 

 sions, as shown by our experience of the past four years. The cold- 

 mixed stock emulsions, upon standing, break down faster than the boiled 

 emulsions, especially in cold weather. For this and other reasons, there 

 is a greater likelihood of injury with the cold-mixed emulsions than 

 with the boiled emulsions. 



5. Conipatibilitv with Fungicides 



The boiled soap-oil emulsions will mix with Bordeaux, but not with 

 lime sulfur. Most cold-mixed emulsions will mix with both Bordeaux 

 and lime sulfur. \Miile there is some precipitation in the cold-mixed 

 emulsions with lime sulfur, yet effectiveness does not seem to be impaired, 

 as will be seen by applications 69 and 70 in Table IX (pp. 115, 117). 



6. Kinds of Cold-mixed Emulsions and Methods of Making 



Bordeaux. — Cold-mixed Bordeaux-oil emulsion is made by pumping 

 together, without heating, oil and Bordeaux mixture. Most of that used 

 in our experiments Was made with equal parts of oil and Bordeaux. 

 Three pumpings gave a product appreciably better than that made with 

 two. In most of our work, a 4-6-50 Bordeaux (using hydrated lime) 

 was used. 



Calcium Caseinate. — Kayso, or any form of calcium caseinate, usually 

 makes a good emulsion. It is probably the easiest to make of any of 

 the commonly used cold-mixed emulsions, and one of the cheapest. The 

 formula generally used is two gallons of oil and one gallon of water in 

 which is mixed four ounces of calcium caseinate. Calcium ca.-^einate 

 should be used fresh to get the best results. 



Iron Sulfate-Limc. — Iron sulfate and lime can be used in place 

 of the copper sulfate and lime of the Bordeaux mixture. In our experi- 



