PRUNING 261 



warm, dry weather, and when the wound is not shaded 

 after peehng; otherwise, injurious fungi are apt to in- 

 fect the ruptured cells. 



429. Protective pruning. — Dead or dying members of 

 a plant sliould be promptly remo\'ed, since they more or 

 less endanger its well-being. Dead branches of any con- 

 siderable size invite decay into the stem, which often re- 

 sults disastrously (419). Branches that are dying from 

 infection by a parasite, such 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), and those that interfere by too close con- 

 tact should be cut back in proportion to the interference. 



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. 

 A short-handled hoe or a box-scraper is convenient for 

 the work. Trees subject to sun-scald should generally 

 not be scraped unless other trunk protection is given. 



430. Maturative pruning. — Pruning to hasten ma- 

 turity is seldom practiced. In nursery trees that tend to 

 grow too late, and are thus subject to winter killing, the 

 leaves are sometimes removed two or three weeks before 

 the time when hard frosts are expected, to encourage 

 ripening of the wood. 



The later tobacco plants in a plantation are usually 

 topped at the time the main crop is pushing the flower 

 stalk, which causes their leaves to mature in season to 

 be harvested with the rest of the crop. 



For a discussion of pruning to retard maturity see 

 paragraph 158. 



