The maintenance of trees, shrubs, and vines, since they are almost invariably planted where they are expected to remain permanently, presents fewer difficulties than the care of perennial plantings, except where plants become diseased or subject to insect attack. Maintenance is confined mostly to cultivation, feeding, watering, pruning, and spraying.
Pruning has been discussed in Chapter III (Pruning), but there is an analogous practice often followed by "tree doctors," namely, the scraping of bark from trees, which should be touched on here. The main object and accomplishment of tree scraping seems to be the providing of work for "tree doctors" during dull seasons. The ultimate consequences to the tree are seldom beneficial, and often fatal. Instances have occurred where handsome shade trees were scraped down to the cambium by ignorant "doctors" and promptly died. The outer bark of trees is placed by nature as a protective covering and should not be removed, except in the case of those trees, such as hickory and plane tree, which naturally shed bark in large scales, and then only when these scales are harbouring insects which cannot be otherwise destroyed. The criticism of the so-called tree doctors is, however, not intended in the least to discredit really expert tree surgeons nor to discourage the employing of them. Quite to the contrary, it should be noted that these men can render most valuable service and that often a greatly prized tree can be saved for many years and its growth greatly improved by having it wisely cared for. The supporting of branches where a crotch might cause a splitting of large limbs is too often neglected. The removing of broken branches often prevents decay from entering into the heart of the tree. The taking out of crossing limbs often makes possible a symmetry of development that otherwise would never be realized.
*See also Chapter III (Pruning) on "Pruning" and Chapter VIII (Winter Protection And Mulching) on "Winter Protection and Mulching."
The proper filling of a cavity, after the wound has been scientifically dressed, will enable the cambium to begin to grow over the space and in time to cover it entirely with tissue that will greatly promote future growth of the tree as a whole while at the same time it removes a disfigurement. But before the welfare of valuable trees is entrusted to a man who professes to be able to restore them there should be valid assurance of his being in every way proficient and thoroughly competent.
Shade trees seem to be less intelligently maintained than shrubbery. It is a matter of common knowledge that the roots of trees spread as far or farther than the tops, and that most of the feeding roots are at the extremities of the large roots. Many experiments have proved that the effect of fertilizers is rarely felt very far in a lateral direction from the place where applied. Therefore, when feeding a shade tree do not bank a small pile of strawy manure around the trunk, as this encourages mice only. Spread the mulch well out over the whole area covered by the top of the tree, and neglect, if any, the area near the trunk. In case of shade or orchard trees which are not vigorous and which require feeding, recent experiments seem to show that applications of nitrate of soda and acid phosphate are effective. Quantities up to ten pounds for each tree may be used on old trees either spread evenly over the surface of the ground underneath the tree or introduced beneath the sod in quantities of a handful deposited in the bottom of holes made by a crowbar at staggered intervals of eighteen inches. Bone meal is probably one of the best fertilizers to be used in preserving the vitality of shade trees. A successful method of applying bone meal is that of spreading it broadcast over the lawn surrounding the base of the tree. This fertilizer, which is slow acting, should be applied during the winter or very early spring months, at the rate of at least twenty-five or fifty pounds for trees from ten to twelve inches in diameter, and at a proportionately less rate for trees of smaller diameter. This fertilizer should be applied at least once in two years. It is much better to apply a less amount and to fertilize the trees each year.
Most of the deep-rooted shade trees, such as oaks, seldom need watering after they are once established, but it is often advisable to grve shade trees a heavy watering in time of drought Surface sprinkling is not desirable as it encourages surface rooting and seldom does much good. In case it is necessary to water a shade tree the best plan is to throw up a shallow embankment of earth around the tree just outside the spread of the branches if possible, and flood the enclosed area at intervals not more often than once in five or six days. Many trees and shrubs will be much benefited in time of drought if their tops are sprinkled at sundown on very hot days.