Pruning. 245 



The cut should generally toe made at right angles with 

 the toranch, rather than parallel to the supporting mem- 

 ber, since it is important that the wound be no larger 

 than is necessary. Wounds so large that they cannot 

 heal promptly should be painted with lead and oil paint 

 to preserve the wood. 



419. Unhealed Wounds Introduce Decay into the heart- 

 wood of trees. Since the cells of the heartwood contain 

 no protoplasm (72) and are always moist, they form a 

 congenial field for certain destructive fungi (321), that 

 having once gained entrance, sooner or later destroy the 

 heartwood of the whole trunk, thus greatly weakening 

 it and preparing the way for the final destruction of the 

 tree. 



420. Objects of Pruning. If intelligently performed, 

 pruning has one of four objects in view, viz. : 



a — To change the form of the plant, as to outline or 

 density {formative pruning). 



b — To stimulate development in some special part, as to 

 promote the growth of wood or the formation of iiower- 

 buds {stimulative pruning). 



c — To prevent some impending evil to the plant, as to 

 arrest or exclude disease {protective pruning). 



d — To hasten or retard maturity {maturative pruning). 



A — Formative Pruxixg 



This aims to regulate the form of the plant with refer- 

 ence to outline or density, or to strength of stem. Pruning for 

 outline includes pruning (a) for symmetry ov .piciuresque- 

 ness; (b) for stockiness or slenderness. 



421. Pruning for Symmetry aims to develop in the plant 

 a head that is symmetric with reference to its trunk. 



