SOME FACTORS GOVERNING THE TREND AND PRAC- 

 TICE OF FOREST SANITATION 



By J. R. Weir^ 



One of the most important phases of scientific forestry, and 

 in many respects the most important if the largest possible amount 

 of merchantable material is to be obtained, is the protection of 

 forests from their numerous natural enemies. This work falls 

 into three main divisions — protection against fire, against insects, 

 and against diseases caused by fungi. It is my purpose here to 

 discuss some of the factors governing the trend and practice of 

 forest protection with special reference to fungous diseases. 



Although forest protection has only recently been directed 

 into the proper channel for profitable returns, still the preven- 

 tion of injury to the forest is the oldest branch of forestry and 

 was the first to receive attention. We are reminded of the great 

 royal forests established by the early English kings and the 

 scrupulous care with which they were tended. True, the earliest 

 protection of forests was almost wholly in the interests of the 

 chase, still a way was opened which led to a more rational view 

 of the benefits to be derived from a protective forest policy and 

 later laws were devised regulating planting and the utilization 

 of forest products. The control and prevention of fungous 

 diseases in plants as a practical branch of Botany has only come 

 into prominence in recent years. The old writers before the 

 Christian era knew some of the more virulent plant diseases, 

 especially those which assumed the nature of an epidemic. But 

 this knowledge was so permeated by the philosophy of the time, 

 and as such visitations were looked upon as emanating from the 

 deities, nothing definite could possibly come from it. Not until 

 a true knowledge of the significance of parasitism in plant life 

 became general was any advance possible. This was necessarily 

 dependent on the miscroscope by means of which the presence 

 of the parasites could be detected. 



Reviewing the trend and development through which many of 

 the working hypotheses of the present day were first conceived, 

 it is interesting to note the varying view points as to the nature 

 and relationship between living things and the inanimate world, 



^ Consulting Pathologist, U. S. Forest Service, District 1. 



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