148 



MANUAL OF GARDENING 



162. Bridge-grafting or in- 

 arching from saplings 

 planted about the tree. 



"It has been found that there is a tendency for portland ce- 

 ment to contract from the wood after it dries, leaving a space 

 between the wood and the cement through which water and 

 germs of decay may enter. A remedy 

 for this defect has been suggested in 

 the use of a thick coat of tar, or an 

 elastic cement which might be spread 

 over the surface of the 

 cavity before filling. 

 The cracking of port- 

 land cement on the 

 surface of long cavities 

 is caused by the sway- 

 ing of trees during 

 heavy storms, and 

 should not occur if the filling is correctly done. 

 *'In addition to the preservation of decayed 

 specimens by filling the cavities, as above out- 

 lined, it has been proposed to strengthen the 

 tree by treating it as shown in Fig. 162. Young 

 saphngs of the same species, after having be- 

 come established as shown, are grafted by ap- 

 proach to the mature specimen. 



''Injury frequently results from error in the 

 method of attempting to save broken, or to 

 strengthen and support weak branches that 

 are otherwise healthy. The means used for 

 supporting cracked, wind-racked, and over- 

 laden branches which show a tendency to spHt 

 at the forks are bolting and chaining. The 

 practice of placing iron bands around large branches in order 

 to protect them has resulted in much harm ; as the tree grows and 

 expands, such bands tighten, causing the bark to be broken and 

 resulting after a few years in a nartial girdhng (Fig. 163). 



163. Faulty meth- 

 ods of bracing 

 a crotched tree. 

 The lower meth- 

 od is wholly 

 wrong. The up- 

 per method is 

 good if the bolt- 

 heads are prop- 

 erly counter- 

 sunk and the 

 bolts tightly 

 fitted; but if the 

 distance be- 

 tween the 

 branches is 

 great, it is bet- 

 ter to have two 

 bolts and join 

 them by hooks, 

 to allow of wind 

 movements. 



