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in the first instance, those parts where the vessels are 

 the most weak and tender ; now these, past dispute, 

 are in the branches. Moreover, we generally see the 

 youngest branches the earliest sufferers. 



Pruning has a powerful influence in preventing the 

 occurrence of the canker. We remember a standard 

 russet apple tree, of not more than twenty years' 

 growth, with a redundancy of ill-arranged branches, 

 that was excessively attacked by this disease. We 

 had two of its three main branches and the laterals of 

 that remaining carefully thinned ; all the infected 

 parts being at the same time removed. The result 

 was total cure. The branches were annually regu- 

 lated, and for six years the disease never re-appeared. 

 At the end of that time the tree had to be removed, 

 as the ground it stood upon was required for another 

 purpose. 



All these facts unite in assuring us that the canker 

 arises from the tree's weakness, from a deficiency in 

 its vital energy, and consequent inability to imbibe 

 and elaborate the nourishment necessary to sustain 

 its frame in vigour, and much less to supply the 

 healthy development of new parts. It matters not 

 whether its energy be broken down by an unnatural 

 rapidity of growth, by a disproportioned excess of 

 branches over the mass of roots, by old age, or by the 

 disorganization of the roots in an ungenial soil ; they 

 render the tree incapable of extracting sufficient nou- 



