SELECTING AND PREPARING MATERIALS 279 



trade names. They may serve as spreaders and stickers as 

 well. They are in a liquid or powder form and usually have a 

 soap or casein base. Bordeaux mixture is an excellent emul- 

 sifier and may be used as a fungicide in the same application. 

 A miscible oil is a clear oil which contains an emulsifying 

 agent and will mix when poured into fresh soft water. An 

 oil emulsion is a grayish white cream which contains an emul- 

 sifying agent and consequently may be diluted with water. 

 These two are the most popular forms of commercial orchard 

 spraying oils. 



Kinds of Oil 



Petroleum oil is used to control lecanium, San Jose, and 

 scurfy scale; for cleaning up bad outbreaks of leaf roller; to 

 check pear psylla, European red mite, and probably apple 

 red-bug eggs. It is used for dormant spraying only, and if 

 applied for too many years in succession it may injure the tree. 

 Petroleum oil may be bought as a crude oil, in a miscible 

 form or as an emulsion. 



Tar oil, a coal-tar creosote product, usually sold as an 

 emulsion, is used to control aphid eggs, bud, moth, oyster 

 shell scale, and scurfy scale. It is not effective against San 

 Jose scale. This oil is very caustic to the skin, and if the 

 weather is at all windy during spraying, it must be handled 

 with care. It is applied during the dormant period. 



D.N, oil has been used as a dormant spray with some de- 

 gree of success. D.N. is an abbreviation for the mixture of 

 96 percent by weight of lubricating oil and 4 percent of dinitro- 

 orthocyclohexylphenol. As yet it should be used cautiously 

 until more experimental work has been done. 



Tar lubricating oil, a mixture of tar oil and petroleum oil 

 in various proportions, is sold by some manufacturers; it is 

 used as a complete '^clean-up'' dormant application. It may 

 be mixed and diluted so that there will be the proper amount 

 of each type of oil to control the combination of insects 

 which are attacking the trees (see Table 40, page 290). Tar 



