148 PRUNING OF PLANTS 



observed. All wounds on a plant are healed by the cell sap 

 carrying food to the wounded part. If this wounded part is 

 in the line of the sap movement the wound is readily healed, 

 but if the wound is not in line with this channel in which the 

 sap flows it will not be healed. Since the only way that the 

 sap is kept flowing in this channel is by the presence of leaves 

 on the trees, it is at once apparent that if a limb is cut off, 

 the leaves are removed and consequently the sap does not 

 pass out into any part of the stub that remains. When a 

 stub is allowed to remain no healing can take place and in 

 a short time disease will enter the tree and finally cause its 

 death. 



The pruning of a plant disturbs the balance between the 

 top and the roots. It is a well known fact that the top and 

 the roots of a plant maintain an equilibrium and when a 

 part of the branches is cut off it breaks this balance. The 

 natural tendency then, is to have the plant develop enough 

 new branches to bring about this balance between the roots 

 and top. When pruning, then, it is necessary to take into 

 consideration this principle, and not prune too severely, so 

 that the balance of the tree is not so radically disturbed. 

 Constant and uniform pruning every year avoids any bad 

 effects from this source, but spasmodic and severe pruning 

 greatly interrupts the equilibrium of a plant. 



Time to Prune. — The time for pruning varies over a con- 

 siderable period and with different plants, and we recog- 

 nize winter and summer pruning. With most horticulturists 

 pruning is done during the late winter and early spring 

 months. As a rule, pruning late in the spring, just before 

 growth begins, is the ideal time for most plants. Late 

 pruning of this kind serves to remove all winter-killed 

 branches with no chance of more to occur. It also has the 

 advantage of starting the healing process at once and the 

 wound is exposed for a much shorter time. 



Summer pruning may be practiced to regulate the form of 

 a tree or induce growth in accordance with some specific 

 purpose. It also has a tendency to produce fruit buds by 

 checking exuberant growth and by encouraging short lateral 

 growths or short spur-like branches in the center of the tree. 



