Great Sores From Little Lesions Grow, But The Home Owner Can Soon Learn Minor Surgery

Like light pruning, the repair of wounds and cavities, and the bracing of trees' weak spots, are good things for the home owner to practice on a small scale, or to study and supervise, if only because they will help him to recognize the larger needs of his major trees when he does call in professionals.

What a scalpel is to an M.D. a jackknife is to a tree owner: his tool for preliminary work on wounds of all degrees. Pocket arsenals can be bought which contain every weapon from a can opener to a farrier's awl, but for tree repair only two knife blades are needed. One should have a long, narrow "toad-stabber" point for probing and picking out. The other should be short and sturdy with a more rounded end and a fine-honed cutting edge, for tracing and carving.

Tracing is when you incise around a wound to cut back to undamaged bark, and bevel its edges down to the juicy cambium layer. From those juices will grow the callus that is a tree's scar tissue for healing its wounds. Basic to the repair of all tree wounds is remembering that a tree's sap circulation is longitudinal, not lateral, throughout all its members. To help any wound heal you must shape it at both ends into points, like the ends of an ellipse. This lets the cambium channels merge again after having been separated by the wound's width. Within these rejoining points callus will form evenly, without interruption, about a half inch each growing season.

No abrasion or slashing of the bark deep enough to damage the cambium layer should be ignored, especially in young trees. Bark lesions are just like bleeding cuts in your own skin. Great sores from little lesions grow, or can grow, and they are a pleasure for any tree lover to mend when he finds how simple it is.

Right after tracing and shaping any wound, shellac its edges to protect the newly exposed cambium. Then take your time carving and scraping smoothly off the wound's surface all shredded, dry, or discolored fibers down to solid sapwood, and apply a neat dab of tree paint. Do the same wherever a branch has been recently torn off its parent member, before decay can set in. (See Fig. 6.)

A form of damage that often puzzles new tree owners is when bark, usually on lower trunks or limbs and especially in young maples, splits open and separates from the wood for no apparent reason. This is caused by frost action, after a midwinter or "false spring" thaw. It can injure trees severely. The thing not to do is peel off the loose bark, thus exposing bare wood, until callus growth at the edges of the wound is well begun, in late spring or summer. Then chip away the flaked bark, shape the lesions (with pointed ends) and paint them up, taking care not to paint the new callus.

When you pruned your first tree (Chapter V) you cut off some dead branches and stubs whose decay had progressed into the branch bases, penetrating beyond the cambium to form an incipient cavity. (See Fig, 7.) One of these lesions, at a handy height, is a good place to try your hand at cavity repair. Besides your knife you will need for this work a 3/4-inch gouge (curved) chisel and a wooden or hard-rubber mallet. The object of your work will be, after pruning the stub (Fig, 7), to trace and shape the wound with your knife, to cut away all dead tissues in and around the lesion so that callus can roll in and make a healthy seal. (See Fig. 8.) Use your chisel, tapped by the mallet or the heel of your hand, to chip and shave away all discolored material down to living wood. Slope and smooth the excavation as you go and don't worry if, on this first attempt, you go deeper than you wish you had. Shape, smoothness, and perfect drainage are the important results. Careful painting and the healing process will in time take care of your slips.

Decay progresses in wood at about the same rate as growth, going chiefly in and down instead of out and up. When its invasion at a stub lesion has gone past the sap-wood into heartwood, you will not only have to gouge out the decay's top and back limits but also follow its inroads downward to their bottom, which may be surprisingly deep. That is where little stub lesions deceive us. In trying to heal shut at their original openings, they conceal their true depth and thus escape or postpone attention.

To find out how deep the decay has gone, enlarge the original opening enough to let you probe downward with your knife or chisel. If you still can't find hard bottom, take test borings from the outside with a quarter-inch auger, slanting the bit upward so that the hole will drain when you do get a bottom one. What you do next will depend on several things, but your main objects will stay the same: to clean out all the punky wood possible, paint all the exposed good wood that you can reach, and establish free drainage of the cavity.

If the decay goes back into heartwood only a short distance and downward no farther than your chisel can reach, you may elect simply to cut open an exterior V channel through which you can be sure of excavating and painting thoroughly. (See Fig. 9.) If the cavity's vertical depth is great, you may decide to establish drainage by enlarging your test hole and inserting a tube (copper or galvanized), meantime carving back the cavity's upper wall surfaces as best you can. (See Fig. 10.) Often this compromise is best, to avoid an ugly gape in the tree and conserve the sapwood shell. The decay remaining within can be slowed by flushing out the cavity with disinfectant (copper sulphate or mercury bichloride solution), and this process will give you a check on your drainage, through the tube. A dry hole rots much more slowly than a damp one.

It does not take many years for a cavity the size of the one in Fig. 7, which started from a small branch stub, to enlarge to one the size shown in Fig. 11. Here the heartwood has been invaded so far as to cause structural weakness. When such a cavity has formed in a branch or minor leader, the simplest procedure is to amputate the whole member below the cavity. In a main leader or trunk, salvage is still possible by full excavation of the decay, through a frontal channel down its whole length (which matters much less than its width), followed by the installation of internal iron bracing rods. (See below.) These are criss-crossed, at different levels, at spots where the cavity's sapwood-and-bark shell affords good purchase.

Tree "surgery" as it was first sold years ago consisted largely, and more truly, in tree "dentistry": plugging up cavities with a variety of fillers, chiefly concrete, which were supposed to arrest decay and strengthen the tree. Seldom did cavity-filling do any such thing for trees. Unless a perfect seal is achieved, decay persists more surely in a "filled" cavity than in one left open, well drained and periodically painted. Structural strength is as often lessened as it is increased by the filler's inert, non-integral bulk, against which the tree's living tissues weave and chafe. Nowadays, cavities are seldom filled except for appearance's sake; and this work, which is at once the most expensive and least important aspect of tree surgery, should be left to experts only. With this exception:

Where a cavity extends down a trunk into the root-crown, it often pays a tree owner—after he has cleaned out, painted, and rodded the hollow above-ground—to excavate the decay downward as far as he can, then lay a base of small stones and pour filler (an asphalt-sawdust mix) into the hollow until its surface rises a few inches above ground level. When it hardens, this fill by its weight alone may improve the tree's balance and anchorage. The top of the fill can be kept sloped and moisture-sealed against the tree's butt shell with thick tree paint or a plastic.

Besides butt cavities and the girdling roots mentioned in Chapter IV, other troubles in his trees' lower extremities that a home owner can spot and attend to are burns, root scars, and cavities, animal damage (gnawing by rabbits, rubbing by horses and cows, antler-raking by deer), and insect invasions (ants, grubs, borers). Against these latter, potent poisons now come in aerosol form. A few squirts from the can's nozzle and you fill the beasties' tunnels and galleries with lethal DDT vapor—much more effective than the pastes and slurries we used to mix up and poke in.

Sometimes trees "bleed" persistently from old wounds that appear to be almost, but not quite, healed. The exudate smells foully and it discolors, even kills, all bark that it oozes down over. This is called "slime flux" and it comes from high sap pressure in poorly conditioned trees. Actually it is of two kinds, "brown" and "alcoholic." The former is a leakage of xylem (heartwood) sap from the root system, darkened by fungi and bacteria. It may be checked (but seldom cured) by boring holes into the heartwood at intervals directly below the old, fluxing wound, and inserting pipes, which should be long enough to carry the drip out away from bark and roots. The more curable "alcoholic" slime is just that—a leakage of phloem (outer layer) enriched sap from the tree's crown, in which sugars and starches are fermenting. This kind, white and bubbly, comes out low on the tree as a rule. It can usually be stopped by retracing and redressing (with shellac) the old wound that is exuding. All trees showing slime flux should be generously fed.

Crotch hollows also come under the heading of wound repair. Many otherwise well-formed trees (particularly yel-lowwoods) develop deep pockets where their leaders, especially large multiples, branch out from the trunk. In these hollows, which resemble inverted armpits, not only water but fallen bark and wind-blown soil can accumulate. Often parasite plants or seedlings from the tree itself will start growing there. Danger arises from wet-rot and frost pressures. Averting such pockets early in a tree's life or altering them after they have developed is not difficult. The problem involved is purely one of drainage. An open channel can be gouged, or a tube inserted, to the crotch hollow's lowest point. To keep the pocket from collecting debris, fit a sheet-metal cap over it. This can be done also over cavities, to keep out squirrels and such. The tree will accept the shield, with a callus roll, as part of itself if you trace back the bark to open a ledge of wood and tack the metal to it.

Crotches forming a wide angle are always stronger than acute-angle or V crotches. Often the latter look strong because they appear to be reinforced by a roll of callus. But that roll was formed, on the outside only, after that crotch was cracked or actually sprung open some time ago by heavy pressure, as of wind or snow, applied to the member aloft. Unlike a metal joint mended by arc welding it is not "stronger than ever" after its healing, but highly prone to refracture in another big blow or snow. It is particularly important to inspect trees near architecture or over driveways for V crotches, callused or otherwise, for they are inherently weak and hazardous. In trees small enough to handle himself, the home owner can reinforce a faulty crotch in one of two ways, or both; rodding and/or cabling.

The rodding mentioned above for reinforcing deep cavities is called "wood screw" and it comes in various diameters up to two inches. It is iron bar, threaded its whole length, which is screwed through opposed holes in the hollow tree and sawed off flush to the bark, which will grow over the ends. When wood screw is used to reinforce a weak crotch, the crotch should first be drawn together tightly by a "come-along" (interlooped rope sling, or noose) rigged high up in the members forming the crotch. This is necessary because the bar's threading, being continuous, has no pulling power. Turned with a pipe wrench through holes bored slightly smaller than its own diameter, the rod only holds fast in whatever position it is left. More positive in their action, but more expensive, are bolt-and-nut assemblies which must be measured, cut, and threaded to fit each situation. And the nuts, with elliptical or diamond-shaped washers, must be countersunk into the bark to get them healed over properly. But bolts are best for mending split limbs, which they can draw together.

The optimum position for rodding is about twice the smaller member's diameter above the weak crotch. In case of dire weakness, put one or even two more rods a like distance farther up. (Always coat with tree paint any metal put into living tree tissues. This goes for drain tubes or pipes, too, which need not be driven more than three or four inches into their holes.)

Cabling to support weak crotches, or to brace any of a tree's upper parts by fastening them to other parts, is done with galvanized twist wire in gauges that run from ^4- to %-inch. The cable is fastened to hooks or eyes that may be of the lag (screw-in) or bolt-and-nut type. Loops in the unraveled cable's ends are fashioned by wrapping its separated strands back around itself with pliers. Cables should be installed while trees are in leaf, so that tensions can be properly adjusted, again using the "come-along" to ensure tension enough. The hook or eye should be placed at one-half to two-thirds of the weak member's length above the crotch. The cable should run upward at about forty-five degrees to another hook or eye in the supporting member. (In cabling a tree's tops together for mutual support, this angle can be much less, or even horizontal, the main thing being to oppose weights and stresses judiciously.)

A composite of noosing, cabling, and rodding a weak-crotched tree is shown in Fig. 12.

Under no circumstances should trees or their members be braced by passing wires, cables, or chains around them.

No matter how you stuff or baffle the collars, sap circulation will suffer. When a small tree blows over, you can pull it erect with a rope and prop it there temporarily, to keep its roots underground, with a padded board nailed atop a post. To fix it permanently erect, don't use the time-honored makeshift of guy wires passed through hose. Put a screw hook or eyebolt into the trunk about halfway up and run a cable down at forty-five degrees to a "dead man" buried in the ground. This is a heavy pipe or post, not driven at a slant but laid horizontally at the bottom of a yard-deep "grave," which you dig at right angles to the trunk on the windward side. Pass the cable to the "dead man" through a slanting hole which you poke with your punch-bar, to avoid loosening the earth between tree and grave. (See Fig- 13-)

Once they have been blown over, resurrected trees are likely to go down again if another blow comes before they are securely rerooted. To guard against this, in case the next gale should come from a new angle, put in two or three cables to buried anchors.

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