PLANTING AND CARE OF TREES 



147 



on the trunk or branches of a tree will have any beneficial effect, for 

 these are the result of disease and not the real trouble. These 

 familiar fungus growths are found only on wood that has become 

 diseased as a result of some mechanical injury, which may have 

 occurred several years before. The treatment for such troubles, as 

 mentioned elsewhere, consists in removing the decayed wood con- 

 taining the fungus, sterilizing the wound, and protecting the tree 

 from further infection. 



There are some leaf diseases, like the black-spot or "tar-spot" on 

 the Maple, that sometimes cause injury, but are seldom so serious 

 as to kill the tree. There are other tree troubles that affect the 

 leaves and which frequently cause serious alarm on the part of the 

 owner of the trees. A branch here and there and sometimes one- 

 half or more of the tree will show colored and dying leaves, many 

 of which fall about mid-summer. This trouble is especially com- 

 mon on the Sugar Maple, and it is sometimes very difficult to deter- 

 mine the cause. It is probably caused many times by an unbal- 

 anced condition of the tree. The Sugar Maple develops a large 

 growth of foliage in the spring, and during the dry months of July 

 and August the roots seem to have trouble in supplying enough 

 moisture to take care of the evaporation from the leaves. As a 

 result, some of the less favored branches lose their leaves. Trees 



Fig. 72. Chestnut trees kiUed by the bark disease. 



