464 BOARD OF AGRICULTURE. [Pub. Doc. 



tremendous pressure on the bark which encases it. If the 

 trunk grows, the bark must keep pace with that growth and 

 constantly increase in area. 



As the trees grow older and larger and the bark grows 

 thicker year after year, the outer layers die, and, becoming 

 unelastic, crack under the annual pressure caused by the 

 expansion of the trunk, until they finally, as in the case of 

 very old trees, scale off and fall to the ground. When this 

 process is slow, the bark may become so thick and tough as 

 to interfere Avith the tree's growth. 



Scraping orchard trees has been condemned as a pernicious 

 practice, calculated to injure the trees subjected to it. It has 

 been maintained that the rough bark which adorns the trunks 

 and branches of old trees forms, together with the lichens 

 or so-called ' ' moss '" upon it, a protection from the blasts 

 of winter, and that the removal of this outer covering must 

 work an injury to the tree. Those who see beauty in the 

 forms and tints of this old bark and its adhering vege- 

 table growths have reason, from an esthetic point of view, 

 to object to its removal. But let it no longer be urged 

 that the process is injurious to the tree. This outer 

 bark is dead tissue, and in many cases it would be better 

 for the health of the tree if it could be removed without 

 waiting for the slow process of nature, by which it is 

 inevitfibly shed. While ,it may be some protection from 

 the alternate freezing and thawing of an open winter, its 

 removal very early in the spring benefits the tree. I have 

 frequently asked people who were scraping the outer bark 

 from their apple trees why they did it. They did not know 

 just the reason Avhy, but their usual answer was, " I think 

 it is good for them." Experience has shown this to be true. 

 If the loose outer bark is removed and burned, the harbor- 

 ing places for many injurious insects are disposed of and the 

 insects themselves destroyed. This is the first and most 

 direct benefit of the scraping, but there are others still more 

 important. 



In the work on the gypsy moth, it now and then became 

 necessar}' to remove the rough bark from the trunks of elms, 

 apples, walnuts and some other trees, to prevent the caterpil- 



