PEAR GROWING IN CALIFORNIA. 291 



danger of injury to the tree. Frequently trees are seen that have been 

 tied, when grafted, with strong waxed thread or twine which does not 

 rot, and as a consequence the flow of sap is interfered with and there 

 results an enlargement of the tree at point of union, or even girdling, 

 and the subsequent death of the tree. For this reason tying should be 

 carefully done, using no more twine than is necessary. Cotton knitting 

 thread, Nos. 18 or 20, is recommended. Tying of the thread is not 

 necessary as the end may be pulled into the cut of the whip graft. 

 Waxing over the surface of the twine is frequently practiced; also 

 waxing the twine before use, which precludes the necessity of tying. 



Root-grafts are set out in the nursery row in the spring and will 

 develop tops of sufficient size for planting in the orchard the following 

 spring, making the one-year-old tree which is recommended under prac- 

 tically all conditions in California. 



73 



