266 Principles of Plant Culture. 



a time when the wood is well supplied with reserve 

 food, i. e., some time after the tree has put out leaves. 

 It is most likely to succeed in warm, dry weather, and 

 when the wound is not shaded after peeling; otherwise, 

 injurious fungi are apt to infect the ruptured cells. _ 



C PROTECTIVE PRUNING. 



429. Dead or Dying Members of a plant Should Be 

 Promptly Removed, since they more or less endanger 

 its well-being. Dead branches of any considerable size 

 invite decay into the stem which often results disas- 

 trously (419). Branches that are dying from infection 

 by a fungous parasite, as the apple or pear blight, or 

 the black knot of the plum (323), are especially dan- 

 gerous and should always be removed as soon as dis- 

 covered. Branches that tend to interfere with the 

 growth of others already formed should be checked by 

 pinching (416 a), and those that interfere by too close 

 contact should be cut back in proportion to the inter- 

 ference. 



Scraping off the dead bark scales from old fruit trees 

 tends to remove certain destructive insects or their 

 eggs. It should be done during the growing season, 

 and a short-handled hoe or a box-scraper is convenient 

 for the work. Trees subject to sun-scald should gener- 

 ally not be scraped unless other trunk protection is 

 given. 



D MATURATIVE PRUNING. 



430. a Pruning to hasten maturity. This is seldom 

 practiced. In nursery trees that tend to grow too late, 

 and are thus subject to winter killing, the leaves are 



