Old trees with insecure branches can often be saved from destruction by fastening the main branches together on to the trunk. The common practice of putting an iron collar round the branch is a mistake. The iron prevents the branch expanding naturally, and ultimately chokes it. A better way is to use a strong iron rod with a plate at the end, and instead of supporting the branch by encircling it, a hole is bored right through the centre of it, through which the rod is pushed from the outer side. The rod should be of tough iron or steel, and should exactly fit the hole bored by the augur; the portions embedded in the wood should be smeared with coal tar before they are pushed through, so as to make the holes as nearly as possible air and water-tight. One end of the rod should be "threaded" sufficiently to allow of the limbs being braced slightly by screwing up the nut, and thus supporting some of their weight. Finally, the bark should be neatly cut away so as to let in each of the iron plates closer to the living wood, for by this means the time required for closing over the plate by new wood is shortened. In this way the weight is borne by the iron plate, which should, by removing sufficient bark, be allowed to fit close in to the wood. New bark will gradually close over and hide the plate, and instead of an ugly collar cutting into the wood, the only evidence of artificial aid is the rod coming from the inner side of the branch.
Branches or snags that have to be removed should be sawn off quite close to the trunk or larger branch from which they spring. When a stump, even not more than a few inches long, is left, the new bark and wood are unable to close over it, and the wood ultimately decays and acts as a medium for moisture and fungoid diseases. The saw should travel from point A to B, as in the sketch. When a stump is left (as would be done by sawing off at C D) decay sets in sooner or later. Although the tree often succeeds in healing over the dead part, it more often fails to do so until the decay has reached the trunk itself. With the softer-wooded trees like the Horse-Chestnuts disease frequently reaches the heart of the tree quickly by these means. A coating of liquid tar over the wound, renewed once or twice until the new bark has closed over, is a sure protection against these evils.