5. A dead limb with the bark falling off indicates that it died at least
three months before and is, therefore, less safe than one with its bark
tightly adhering to it.

6. Branches are more apt to snap on a frosty day when they are covered
with an icy coating than on a warm summer day.

7. Always use the pole-saw and pole-shears on the tips of long branches,
and use the pole-hook in removing dead branches of the ailanthus and
other brittle trees where it would be too dangerous to reach them
otherwise.

8. Be sure of the strength of a branch before tying an extension ladder
to it.



STUDY IV. TREE REPAIR

Where trees have been properly cared for from their early start, wounds
and cavities and their subsequent elaborate treatment have no place. But
where trees have been neglected or improperly cared for, wounds and
cavities are bound to occur and early treatment becomes a necessity.

There are two kinds of wounds on trees: (1) surface wounds, which do not
extend beyond the inner bark, and (2) deep wounds or cavities, which may
range from a small hole in a crotch to the hollow of an entire trunk.

Surface wounds: Surface wounds (Fig. 116) are due to bruised bark, and a
tree thus injured can no longer produce the proper amount of foliage