26 MASS EXPERIMENT STATION BULLETIN 397 



Small wounds on slender branches do not ordinarily require protection, but 

 may be treated on valuable trees as a precautionary measure. When pruning 

 operations include so many tmall branches that treatment of all cut surfaces is 

 impossible, a safeguard for prompt healing is the careful use of a sharp hand or 

 pole piuner. In using an ordinary hand pruner with a curved blade, especially 

 on surfaces which are not to be treated with a protective covering, care should 

 be taken to hold the pruner so that the supporting base may bruise only the dis- 

 carded twig, Pruning hooks should be Uied only with considerable caution. 



In making secure one's position while treating wounds in remote parts of trees, it 

 is often necessary to resort to the use of ropes. Experienced workers use ropes 

 extensively both while pruning and while treating tree wounds. The amateur 

 may frequently find that he is able to remove branches without the aid of ropes, 

 but they may be necessary to establish a safe position before engaging in extensive 

 wound treatment activities. The wearing of spurs, however, is never advise ble 

 in operations where the tree being treated is to be retained. 



Pruning. Pruning is an important part of any tree improvement program 

 and may be accomplished at almost any season of the year when practicable. 

 In spring, when tree growth is most active, wounds inflicted during pruning tend 

 to heal more rapidly than at other seasons. However, bleeding is most copious 

 at this time, and loss of sap may somewhat weaken the trees as well as prove a 

 nuisance along streets and highways. For these reasons, excessive bleeders, such 

 as birch and maple, should always be pruned later in the season. Pruning when 

 the tree is in full leaf also has advantages in that dead and weakened parts are 

 then more obvious; and street and park trees are often pruned in winter when 

 spraying and other tree work programs are less pressing. 



Whether the pruning work to be accomplished is simple thinning, extensive 

 trimming, topping, or pollarding, the technique of removing branches should 

 receive careful attention. On large limbs the first operation should be a cut made 

 with a saw on the under side of and somewhat less than half way through the 

 limb at approximately one foot from the ultimate pruning point (Fig. 12, A). 



This should be followed by a cut on the upper side of the limb about two inches 

 farther out than the lower cut. Cuttmg with the saw should be continued until 

 the limb falls (Fig. 12, B). 



A third cut made at the ultimate pruning point will remove the stub and leave 

 a clean cut surface of minimum size for sterilizing treatment and at the same 

 time promote a rapid callus growth (Fig. 12, C). 



An attempt to complete the cutting in one operation on the upper side of the 

 branch will most frequently terminate unhappily, in an ugly enlarged wound 

 surface which will not callus over but will enqourage slime flux and defy satis- 

 factory later treatment. 



Following storms, the prompt pruning of broken branches is essential in treat- 

 ing damaged trees. A saw which makes a wide cut is the best implement to use 

 in removing large branches. A strong sharp knife, a mallet, and a chisel will com- 

 plete the necessary instruments for removing accessible limbs. Bark or wood 

 which is splintered or loosened should also be removed with a sharp cutting 

 implement and the same protection against infection should be employed as in 

 the case of wounds. 



Doubtless there will be instances in which all efforts to restore symmetry to 

 a storm-injured tree by pruning will fail. In such cases, severe pruning of the 

 f-ntire top of the tree, or pollarding, may be the best solution to the problem. 

 Most trees respond to pollarding in ^ome degree, and certain trees, like willows, 



