REPORT OF THE STATE ENTOMOLOGIST I912 85 



in considerable measure upon climatic conditions. The vigor of 

 the roots and the lower portion of the trunk, which latter fre- 

 quently escapes injury probably because of the thicker bark hin- 

 dering penetration of vital tissues, is shown by the numerous 

 sprouts on the lower part of badly affected trees. This new 

 growth may be moderate in character or extremely vigorous, much 

 depending upon the vitality of the tree and the number of sprouts 

 developing. 



Miscible oils. An emulsion is defined as " a mixture of liquids 

 insoluble in one another, where one is suspended in the other in 

 the form of minute globules.'' There is no hint of a chemical 

 change, the oil is simply more finely divided and, as a consequence, 

 more evenly distributed through the preparation. It is still oil and 

 possesses the properties of oil, as is readily seen on the disinte- 

 gration of the familiar kerosene emulsion. The term " miscible 

 oil " has been employed in economic literature to designate emul- 

 sions or preparations of oils, usually petroleum, mixing readily 

 with water. A number of these have been placed on the market 

 under various trade names. Experience has demonstrated the 

 utility of a general designation for this class of products. The 

 commercial emulsions are usually more stable, that is, they dis- 

 integrate less readily than the homemade kerosene emulsion. They 

 contain oil in practically an unchanged condition so far as chemi- 

 cal and physiological properties are concerned, and may be ex- 

 pected to produce effects upon plants corresponding to the amount 

 applied, other conditions being uniform. 



Injury by miscible oils. Many have been repeatedly assured 

 that miscible oils, especially certain commercial preparations, can 

 be applied to plants without injury. One manufacturer states 

 that it is " absolutely impossible " for his product " to injure a 

 tree where the simplest directions are followed." Miscible oils can 

 and have been used under conditions which would seem almost to 

 preclude the possibility of injury. Nevertheless, we believe there 

 is a risk in employing these materials, largely because of our ignor- 

 ance of the physiological condition of the tree and the kind of 

 weather which may follow the spraying, both of which appear to 

 be important factors. In addition some varieties seem to be much 

 more susceptible to injury of this character than others. Our ob- 

 servations upon petroleum, noted above, appear to indicate much 

 greater danger of penetration during the winter season, a time 

 when the pressure of sap is greatly lessened. A sudden drop in 



