PLANTING AND CARE OF TREES 



149 



layer and the disease soon encircles the trunk of the tree, or a single 

 branch, as the case may be. All parts of the tree above the in- 

 fection dies, and if the infection starts on the main stem or trunk, 

 the whole tree is killed. 



So far, no means has been devised for the prevention or control 

 of the disease. When valuable shade trees become affected in 

 one or more branches, the remainder of the tree possibly may be 

 saved by promptly cutting out the diseased portion. It is import- 



Fig. 74. Diseased Chestnut bark 

 showing- pustules of the parasitic 

 fungus bearing winter spore 



Lnt that the cut be made many feet below the point of infection to 

 avoid carrying the spores on the pruning saw. Great care also 

 should be exercised in avoiding injuries to the bark of the re- 

 maining portion of the tree. Tlie wounds made in cutting 

 out the diseased branches should be promptly painted with tar to 

 prevent further infection. 



INSECT TROUBLES 



How Insects Injure Trees — The caterpillars, as well as some 

 beetles, injure the trees by devouring the leaves. A tree may be 



