Causes. 3 1 



These are always evident upon hard woods, 

 after the thinning of woods and plantations, 

 especially when the thinning has been delayed 

 or is excessive. There is of course in this 

 case a lowering of the temperature and a 

 consequent interruption of the flow of sap ; 

 and to prevent mischief, these branches 

 should be pruned off with a chisel on a long 

 handle, with an upward stroke, to avoid 

 wounding the bark. This may have to be 

 repeated year by year for a while, but the 

 result will well repay the expense. 



Wounds should be avoided as much as 

 possible, as these result in the killing of the 

 sap wood round the part, the lodgment of 

 water in the cavity caused, and, if neglected, 

 an injury to the heart wood itself. 



Ivy, after a while, has an injurious effect 

 upon the bark, by the exclusion of light, air, 

 and moisture, and through its crushing or 

 squeezing power. It should always be cut 

 through near the ground whenever seen. It 

 will die on the tree and soon cease to cling or 

 exclude light and air. When very old and 

 the tree has been already impaired in health. 



