226 SHADE-TREES IN TOWNS AND CITIES 



heart. When the stump is left the new tissue makes an 

 effort to overgrow the stub, so to speak, and the result is 

 that a thick layer of wood is deposited at the base of the 

 crotch. (Plate 26, Fig. 3.) When the stub rots and falls 

 out, this tissue remains like a ring around the opening of 

 the knot-hole. (Plate 44, Fig. 7.) To fill such a cavity 

 properly, it is generally best to make a cut across this ring 

 close to the trunk, A B, Plate 44, Fig. 8, then scrape out 

 all the decayed wood and fill the cavity flush with the saw 

 cut. Although by this means the area of the scar is in- 

 creased it is brought in more intimate contact with the 

 healing callus and will be like a cut of an amputated 

 branch. The callus will form over the wood first (Plate 44, 

 Fig. 9), and then over the cement and bury it. 



Cavities resulting from other causes, such as those made 

 by borers, can be treated the same way. Surface wounds 

 need only a painting with coal-tar; but if the decay is deep 

 it needs scraping and filling with cement. 



Crotches. — It frequently happens that a tree forms a 

 sharp angle by the division, near the ground, into two or 

 three limbs. The addition of the annual layers of wood and 

 the swaying of the tree cause a prying apart of the limbs 

 at this point, and in time a split is the result. It is then 

 necessary to brace the crotch to prevent the branches from 

 breaking off. 



A common though wrong method of repairing such a 

 defect in a tree has been to put a band around the two limbs 

 forming the fork. The result of such a method is shown in 

 Plate 44, Fig. 6. The action of the band around one-half 

 of the circumference of the tree has resulted in partly gird- 

 ling it. It has cut into the layers of new growth and the 

 tree has been disfigured. The proper way to brace a crotch 



