METHOD OF PRUNING. 



177 



FIG. 16. Excrescence 

 caused by bad pruning. 



(Fig. 16.) The wound has nearly healed, yet decay has set 



in and an unsightly excrescence has been formed on the 



trunk of the tree in the effort of healing. If the wound is 



well covered by the new growth of wood 



before injury has been done by the rot, 



the progress of decay is stopped. In 



order to heal readily, a wound caused 



by the removal of a branch should be so 



made that the sap on its way to the roots 



may come in contact with the entire edge 



of the wound without deviating from a 



direct course. 



The Proper Method. Evidently, then, 

 no portion of the amputated branch should 

 be left, but the cut should be made close to 

 and perfectly even with the outline of the 

 trunk or limb from which the branch is removed , without regard 

 to the size of the wound thus made. When this is done, 

 the elaborated sap flows over the wound from the edges, 

 forming callus first at the top and sides, and gradually 

 covers it with healthy, straight-grained wood. The wound 

 is thus healed over and the decay of the trunk is pre- 

 vented. This healing is gradual and may require years 

 for accomplishment, especially if the limb removed is large 

 and the tree old and not vigorous. The annual wood-ring 

 being thickest on a young tree, wounds made on such a tree 

 will heal more quickly than on an old tree. Wounds made 

 near the top of a growing tree heal more readily than those 

 near the base, for the reason that the annual wood-ring is 

 thickest at the top. If the wound is left exposed to the sun 

 and wind during the time required for healing, its surface 

 invites decay. To prevent this we must protect the wound 

 at once by applying shellac or coal tar to its entire surface. 

 The use of grafting wax or other thick coatings- for such a 

 purpose is not recommended, as they are likely to be cracked 

 or pushed off by the growth of the new bark and thus leave 

 the wood comparatively unprotected. A solution of shellac 

 and alcohol, such as is commonly used by painters, is an ex- 

 cellent wood preservative, as it closes the wound, prevents 



