Page:Popular Science Monthly Volume 84.djvu/560

556 advance in the area in which the chestnut naturally occurs. However, we shall consider this point again later.

In common with other forest trees, the chestnut is subject to the attack of several species of fungi which bring about a decay of the heartwood. Normally, the tree is protected from such invaders by its incasement of bark, but when this is injured in any way, a vulnerable spot is opened up through which fungi can enter. Notably is this the case in trees injured by forest fires, for here the living bark as well as the sapwood underneath may be entirely killed in spots, causing the so-called fire-scars, and furnishing an easy ingress for fungi. Once inside, in the heartwood, the fungus may work up and down in the interior of the trunk, softening the wood by its decaying action, or "dozing" it, as the lumbermen say. If the tree, thus deprived of the firmness of its solid cylinder of heartwood, its chief mechanical support, does not fall a prey to the next violent windstorm, it is in any case weakened, and the way lies open for attack upon its last stronghold, the sapwood and living bark.

Another widespread trouble of the chestnut, which I have found of common occurrence in New England forests, but apparently more destructive in the southern Appalachian mountains, is caused by the attack of the two-lined chestnut borer, Agrilus bilineatus. Next to the fungus which causes the bark disease, this insect is perhaps its most serious enemy. It is said to have a preference for trees enfeebled in some way, through such causes as drought, unfavorable soil conditions, etc., yet it is possible that where it breeds in great numbers it may be forced to attack vigorous individuals. In any case I have seen many examples of trees, which to all appearances had been in a perfectly sound condition, being rapidly killed by the attacks of this tiny grub. On opening up the inner bark, the long, sinuous channels of the larvæ were disclosed, now and then with a sharp turn in a lateral direction, the combined effects of several of these galleries resulting in a practical girdling of the tree. Many other insects attack the chestnut, but they are of secondary importance.

Let us next consider the practise of "coppicing." As is the case with many other of our forest trees, the chestnut habitually sends up sprouts from the stumps of felled trees, sometimes more than one hundred of these developing from a single parent stump. These "coppice" shoots grow rapidly, having the well-developed roots of the parent tree at their disposal for the absorption of nourishment from the soil, and enter into fierce competition with one another for light and space. Although in the natural course of events the weaker ones succumb and die out in the struggle, the woodsman may assist nature in this process of elimination by cutting out the weaker shoots early, in order to give the more vigorous ones a better chance. In either case, eventually four or five, or rarely