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Cutting a Tree Limb

There is but one best way to cut off the limb of a tree, i.e., to saw it off smooth and clean oil a level with the surrounding bark, without leaving a projecting stub. No other tool will serve the purpose as well as a sharp saw. The proper method is, shown in the accompanying picture. The cutting done, the fresh wound should be covered with some water-proof substance, like common white lead and oil.

The paint is not expected to heal the wound, nor is the wood expected to heal itself, as animal tissues are able to do. The paint serves two important purposes. (1) It prevents sap from getting out. (2) It prevents germs of decay and other foreign substances from getting in. Meanwhile, the living cambium is forming a ring of new bark around the edges of the wound, and rolling it gradually inward until it meets and closes center. The paint is a temporary covering, the cambium puts at the on the permanent one.

The secret of sound wood in growing trees is the utter exclusion of the spores of wood-destroying fungi which are so small and so light that they float invisible in the atmosphere.

There is a wrong way to cut off a tree limb, which, unhappily, is often practiced. That is to hack it off, leaving a long ragged stub, and to give it no further care. The wound bleeds. Evaporation robs the porous wood of its moisture. The tree diverts into other channels the sap that would have gone into this limb were it still in its place. The stub is left to die. Rain soaks into it. Dust collects in its passages. The spores of wood - destroying fungi lodge in the soil thus prepared for them. They honeycomb the stub and grow downward toward the heart of the tree.

Meanwhile, the cambium forms a roll of healing tissue at the base and tries to swallow the rotting stub, which becomes weakened by decay, and finally falls off of its own weight. Then the wound may close. But the disease which has gotten inside the tree may go on and reduce the trunk to a hollow shell. Or it may affect it but slightly. Rarely does a tree have a fresh wound exposed without contracting tree diseases. The larger the surface, the greater the danger, and the more urgent the necessity for the pruner to do his work well.

Sometimes the ring of healing tissue gets too thickly covered with bark. This happens only when large limbs are cut off. The ring becomes "bark-bound," and this prevents the completion of the healing process. It is a good idea to take a jack-knife and scrape off the tough, dead bark on the inner side of the ring. The cambium layer is enabled to set up growth again. This "corrective surgery" should be done in spring when the activities of the tree are at their height.