Notes on Effects of Kerosene. 169 



8. A building made especiall}^ for the purpose is convenient if 

 large quantities of nursery stock are to be treated. 



9. As potassium C5'anide is a most deadly poison, also the gas 

 generated in fumigating, great care must be taken in using and 

 handling it. Air the room thoroughly before entering it. 



II. EFFECTS OF KEROSENE ON PEACH AND APPLE 



TREES. 



Although the value of kerosene in combating sucking insects 

 was recognized in the early history of spraying, yet it is onl}^ 

 within the past few years that it has been used to any extent in 

 any other form than as an emulsion with soap. But with the 

 advent of the San Jose scale in such force in the East, experi- 

 menters began to turn their attention to kerosene in other forms, 

 and as a result many references to the effects of kerosene have 

 appeared in horticultural literature during the past few years. 

 And yet there is much to learn concerning kerosene audits effects 

 on plant life. From the fact that the results have been so con- 

 flicting without an}' apparent reason, the use of kerosene is an 

 uncertain practice. It is generally conceded by those who 

 have had much experience that the conditions of the weather 

 have a marked influence in determining its effects ; that if 

 applied in bright sunny weather, — a condition which favors the 

 rapid evaporation of the oil, — the liability to injury is greatly 

 reduced in comparison with applications made in cloudy weather. 



With respect to the effect of the 20 per cent mixture of 

 kerosene with water on the buds ofCornus and Pyrus referred to 

 in Bulletin 144, it may be said that they did not suffer in the 

 least. The trees and shrubs sprayed with this strength of 

 kerosene, a year ago, made an excellent growth the past season 

 and are now in good condition. Several months after the Cornus 

 bushes were sprayed, the bark, in some instances, indicated some 

 injury, but it has not proved to be of a serious nature. I think 

 this injury might have been avoided if the climatic conditions 

 had been regarded when the spraying was done. 



It was with the hope of throwing some light on the effects of 

 kerosene and of determining under what conditions it is possible 



