Here are the general
steps in installing a cable to reinforce a weak fork:
1. Do all needed pruning first.
2. Drill each pair of holes exactly
aligned with each other to prevent the
fasteners from wallowing, low enough in
the tree to involve important,
well-attached branches with reliable wood,
but high enough for good mechanical
advantage. Usually cables should be
installed about 2/3 of the distance from the
weak fork to the top of the tree, but this
is a judgment call that depends on
the size and shape of the tree.
3. There will be some decay associated
with each drill hole, and to some extent
this decay will spread vertically within
RODS OR CABLE
FASTENERS IN VERTICAL ALIGNMENT.
The columns of decay are likely to join,
resulting in large weak areas where cracks
and breakage can occur.
4. Instead of lag screws use threaded rod
all the way through the branch or
leader. At each end of each hole, use flat
washers (round, not pointed) seated
flat on bare wood; set square or hex nuts
to hold the rod snugly in place, and
attach the cable to "Ammon nuts" (commonly
used on power pole installations).
See the drawing below.
5. Don't paint the hardware or the wounds.
6. Install cables snugly, but not tight
enough to prevent the cabled branches
from moving somewhat. Cables installed
when leaves are absent should be
moderately tight, never slack, to prevent
the added load of leaves from placing
additional stress on the fork.
7. Inspect all cables annually. Remember that bad forks
always get worse, not
better; and they never "heal." The
long-term power of a cable to strengthen a
tree comes from the tree's closure of
sound wood over the hardware. If decay is
advancing faster than the wound is
closing, consider removing the cabled parts
or the entire tree. When the time comes to
remove the tree, don't take chances
-- DO IT!
8. Take photographs
of the installation, and notes on how and when the work
cracks together doesn't work: the crack will extend at
both ends as the branch flexes.