232 PRACTICAL TREE REPAIR 



decay of trees. Sometimes the causes of decay lie 

 deeper. Its presence may be due to soil exhaus- 

 tion or to the fact that the tree is growing on a 

 soil not naturally suited to it. Dr. Haven Met- 

 calf, forest pathologist in the bureau of plant in- 

 dustry at Washington, speaking of all the diseases 

 of woody plants, says : " The most widespread 

 cause of disease of trees and shrubs is the attempt 

 to grow them in a climate and situation for which 

 the given species are not adapted." This, how- 

 ever, is a subject which is rather within the realms 

 of horticulture and forestry than of tree repair. 

 To foresters it is an immensely important matter. 

 They find that on certain soils decay begins to at- 

 tack the trees of a certain species at, say, fifty 

 years, while on a more favorable soil the harvest 

 can safely be deferred until the trees have stood 

 seventy or eighty years. The obvious lesson to 

 be drawn from this fact is that when trees are 

 planted those kinds should be chosen which are 

 known to do well on the given soil, and that the 

 soil around the trees should be kept in good con- 

 dition. 



