486 PRUNING AND LOPPING. 



notches cut on two opposite sides and shod at both ends in the 

 manner represented in Fig. 112. The wearing of climbing irons 

 should never be permitted. 



To preserve the surface of section from atmospheric influences 

 and from fungus spores, it should be carefully coated over with 

 tar. The section of a dry branch will drink in this tar greedily 

 and become completely inpregnated with it for a good fraction of 

 an inch. The same will be true, but in a less degree, of green 

 branches cut when the sap is down. Wounds made in a tree 

 while it is in full vegetation, always bleed, and t?r put over such 

 wounds would not be able to adhere, much less get inside the grain 

 of the wood. Moreover the exuding sap would obviously decom- 

 pose and give the very best lodgment possible to fungus spores. 

 Hence green branches should be pruned only outside the season of 

 vegetation and before the sap has begun to rise. 



It is obvious that, in view of economy both of money, labour 

 and supervision, pruning should not be undertaken as a separate 

 operation, but combined with any other that may be going on at 

 the time. 



Special Remarks. 



In pruning roadside, grove and garden trees, the value of which 

 as timber trees is a purely accidental matter, a special device for 

 shutting out all atmospheric influences and preventing the entry 

 of fungus spores is to fix a thin tin-plate over the surface of section, 

 after having coated this latter over thickly with tar. The plate 

 should be of the same shape and nearly the same size as the wood- 

 surface on the wound and be kept in place with small iron tacks 

 driven through it along its edge. In a year or two the new growth 

 of wood and bark spreading out from the edges of the wound will 

 cover up the rim of the plate and completely cut off all air- 

 communication with the outside. 



