PRUNING 



PRUNING 



2821 



to California growers following the freeze of January, 

 1913: "Relative to badly injured trees, it appears best 

 not to prune until the new growth has started. It is 

 best to delay the pruning until a distinct line of demar- 

 cation develops between the injured and uninjured 

 wood. At the Citrus Experiment Station last year five- 

 year-old lemon trees were frosted. Good results were 

 obtained by waiting until the new growth had reached 

 from 4 to 5 inches in length; 

 in that instance about six 

 weeks were required. Allow- 

 ing the injured limbs to re- 

 main not only makes it pos- 

 sible to determine how much 

 it is best to prune, but the 

 limbs and leaves afford shade 

 to the bark of the tree, which 

 is accustomed to protection. 



3208. A well-covered 

 wound. The pruning was 

 properly performed, no 

 stub being left. 



3207. A proper cut. The 

 healing tissue arises from 

 the side of the wound, not 

 from the hard wood. 



It may be desirable, in 

 some instances, to spray the 

 trunks and limbs of large 

 and severely pruned trees 

 with whitewash in order to 

 reflect the sun's rays. Wrap- 

 ping the trunks of young trees with loose sun protec- 

 tors would seem extremely desirable. 



"It seems reasonably certain that no injury to the tree 

 can result from any of the materials passing from the 

 frozen oranges into the tree. An examination of those 

 oranges which have been too badly frozen to be fit 

 for shipment shows that most of them only partially 

 have been killed; consequently, they are presumably 

 respiring carbon dioxide. This loss of energy would be 

 saved if the oranges were removed from the tree. There 

 is no experimental evidence, however, to show whether 

 this loss is sufficient to warrant the cost of early removal 

 by hand." 



When to prune. 



It will be gleaned from the above discussion that 

 the time of pruning depends on many circumstances, 

 and chiefly on the result which it is desired to reach. 

 So far as the healing of the wound is concerned, it is 



perhaps best to 

 prune when 

 the vegetative 

 activities begin 

 in spring so 

 that the wound 

 is quickly 

 covered or 

 "healed." For 

 the purpose 

 of checking 

 growth and 

 producing other definite 

 results, it may be neces- 

 sary to prune at other 

 times of the year. As a 



3211. Improper way of general rule, however, 

 applying pruning-shears. the best time to prune 



is in late autumn to early spring, when labor can be 

 had and before the rush of spring work comes on. In 

 practice, it resolves itself largely into a question of the 

 convenience of the operator. 



The wound. 



The wound made by severing a branch heals by 

 means of a callus which forms from the growing tissue 

 between the bark and wood. (Fig. 3207.) This tissue 

 rolls over the wound, finally joining in the center and 

 completely covering the old wood. The old wood itself 

 takes no part in the healing process; in fact, it dies. 

 When the healing is complete, the old wood is merely 

 covered and preserved from external injury and infec- 

 tion, much as fruit in a jar is preserved by being pro- 

 tected with a tight cover. There is no dressing that 

 will hasten the healing process except as it keeps the 

 wood from decay. In other words, the whole object of 

 dressing a wound is to protect it. The dressing hinders 

 bacteria and fungi from securing a foothold and thereby 

 prevents the rot. Wounds that are exposed for some 

 years nearly always become unsound at the center 

 because of the intrusion of these organisms, and even if 

 the wounds should subsequently heal over, the infec- 

 tion may still extend down the heart of the tree and 

 finally cause its death. The best covering for a wound 

 is one that protects it best 

 from weather, microbes, and 

 fungi and which persists 

 the longest. Ordinarily, 

 good white lead paint, ap- 

 plied heavily and renewed 

 occasionally, is a good pro- 



3209. The stub is longer 

 than necessary, although 

 the fault is not a serious 

 one. It will heal well if the 

 old wood is kept healthy. 



tection for fruit trees. 



Grafting-wax may afford 



a fair protection, if it is 321 - Common fault in 



applied warm and thin so P r T ng ,'!? is IT ? cannot 



heal until the stub rots away, 



that it soaks into the tis- and by ^ time the Jj 



sue. If It IS merely spread may be irreparably diseased. 



over the surface, it soon 



blisters and becomes loose and affords relatively little 

 protection. For shade and forest trees, which are 

 treated by "tree surgeons," special dressings and dis- 

 infectants are employed. 



The rapidity with which wounds heal depends very 

 largely on their position on the tree and the way in which 

 they are made. W T ounds along the main branches, which 

 are the leading avenues for distribution of food, heal 

 more speedily than those on the weaker side branches. 

 If the wound is close to the branch it may be expected 

 to heal better. (Figs. 3208, 3209.) If a stub is left sev- 

 eral inches long (Fig. 3210), it seldom heals until it rots 

 back to the main branch or trunk; and by that time the 

 decayed part may have extended deep into the tissue of 

 the tree. It is a common notion that a limb should be 

 cut at right angles to the direction of the limb itself 

 and beyond the bulge at its base. It is a better plan, 

 however, to make the wound parallel to the direction 

 of the branch or trunk that remains, and closer to it. 

 This wound may have a somewhat larger superficial 

 area, but it is, much nearer the source of the healing 

 food-supply. 



