92 NEW YORK STATE MUSEUM 



no injury to soft maples, suggests that the time of appUcation may 

 be extremely important in the case of some trees. The soft maple 

 begins growth in the spring earlier than the sugar maple, and it is 

 very possible that the marked variation in results was due largely 

 to the difference of vital activities then obtaining. 



Conclusions. The use of oils or oil preparations on dormant 

 trees has been followed in several cases by severe injury. 



Trees, as living organisms, respond to climatic and cultural con- 

 ditions and as a consequence their power of resisting penetration 

 and injury by oils undoubtedly varies with the season and prob- 

 ably from year to year. 



Since certain weather conditions promote injury by oils, it ap- 

 pears impossible to be sure that deleterious effects may not fol- 

 low spraying dormant trees with an oil or oil preparation. 



Fall treatment with an oil appears to be more hazardous than 

 spring applications. 



Other things being equal, we believe there is less danger of pene- 

 tration by oil and consequent injury if the applications are made 

 in the spring shortly before active growth begins and presumably 

 offers greater obstacles to entrance by oil or quickly replaces de- 

 stroyed and necessary vital tissues. 



