December, '21] moznette: mango scale control 471 



showed that about S0% of the scales were killed. The soap did not 

 cleanse the trees of the sooty mold, and slight spray injury- was noticed 

 after each spraying, especiall}- on the sunny side of the trees. 



MisciBLE Oil 



The miscible oils, of which there are a number on the market, when 

 used at a strength of one gallon to seventy gallons of water during 

 December and repeating with a spraying at a strength of one gallon of 

 miscible oil to eighty gallons of water during March killed approximately 

 80% of the infestation on the trees sprayed. The m.iscible oils, however, 

 var}^ considerably in composition ; at times they contain harmful ingredi- 

 ents which may cause foHage injury. The m.iscible oils did not seem to 

 spread as effectively as the oil emulsions described below which perhaps 

 accounts for the greater percentage of kill where the oil emulsions were 

 used. 



Paraffine Oil Emulsion 



A num.ber of paraffine oil emulsions as are used against citrus insects 

 were used. They were applied at the rate of one gallon of the stock 

 solution to seventy gallons of water during December and repeating 

 with another spraying during March, using a strength of one gallon of 

 the stock solution to eighty gallons of water. Results showed that 

 from 90% to 95% of the scales were killed where thorough applications 

 were made. 



There are a number of oil emulsions on the m.arket, some of which 

 when combined with the waters used for spraying purposes in southern 

 Florida work very satisfactorily. The waters generally used for spraying 

 purposes in southern Florida come from deep wells in lim.estone forma- 

 tion and are tenned "hard" while those which come from surface wells 

 are as a rule somewhat brackish. There are, however, certain oil emul- 

 sions, which when m.ixed with these waters prove unsatisfactory, 

 because the various salts present in the waters tend to break up 

 the emulsions, causing oil to be set free. This free oil is detri- 

 mental to mango foliage and will cause severe foliage injury. 

 If an oil emulsion, which does not perfectly mix with these 

 waters, is used, considerable inconvenience is experienced by 

 the gradual rising of free oil to the top of the tank. This finally 

 becomes more or less gummy, and the working parts of the pump and 

 machine are so coated with it as to hinder spraying operations. In 

 southern Florida, when oil emulsions are used on the mango, it is ad- 

 visable to test thoroughly to see that no separation occurs, if separation 



