Manual of Gardening Part 13

Mulches also serve a most useful purpose in preventing the ground from packing and baking by the weight of snows and rains, and the cementing action of too much water in the surface soil. In the spring, the coa.r.s.er parts of the mulch may be removed, and the finer parts spaded or hoed into the ground.

[Ill.u.s.tration: Fig. 153: Covering plants in a box.]

Tender bushes and small trees may be wrapped with straw, hay, burlaps, or pieces of matting or carpet. Even rather large trees, as bearing peach trees, are often baled up in this way, or sometimes with corn fodder, although the results in the protection of fruit-buds are not often very satisfactory. It is important that no grain is left in the baling material, else mice may be attracted to it. (The danger of gnawing by mice that nest in winter coverings is always to be antic.i.p.ated.) It should be known, too, that the object in tying up or baling plants is not so much to protect from direct cold as to mitigate the effects of alternate freezing and thawing, and to protect from drying winds. Plants may be wrapped so thick and tight as to injure them.

[Ill.u.s.tration: Fig. 154: Covering plants in a barrel.]

The labor of protecting large plants is often great and the results uncertain, and in most cases it is a question whether more satisfaction could not be attained by growing only hardy trees and shrubs.

The objection to covering tender woody plants cannot be urged with equal force against tender herbs or very low bushes, for these are protected with ease. Even the ordinary mulch may afford sufficient protection; and if the tops kill back, the plant quickly renews itself from near the base, and in many plants--as in most hybrid perpetual roses--the best bloom is on these new growths of the season. Old boxes or barrels may be used to protect tender low plants (Figs. 153, 154). The box is filled with leaves or dry straw and either left open on top or covered with boards, boughs, or even with burlaps (Fig. 154).

Connoisseurs of tender roses and other plants sometimes go to the pains of erecting a collapsible shed over the bush, and filling with leaves or straw. Whether this is worth while depends wholly on the degree of satisfaction that one derives from the growing of choice plants (see _Roses,_ in Chap. VIII).

[Ill.u.s.tration: Fig. 155. Laying down of trellis-grown blackberries.]

The tops of plants may be laid down for the winter. Figure 155 shows a method of laying down blackberries, as practiced in the Hudson River valley. The plants were tied to a trellis, as the method is in that country, two wires (_a, b_) having been run on either side of the row.

The posts are hinged on a pivot to a short post (_c_), and are held in position by a brace (_d_). The entire trellis is then laid down on the approach of winter, as shown in the ill.u.s.tration. The blackberry tops are so strong that they hold the wires up from the ground, even when the trellis is laid down. To hold the wires close to the earth, stakes are thrust over them in a slanting position, as shown at _n n._ The snow that drifts through the plants ordinarily affords sufficient protection for plants which are as hardy as grapes and berries. In fact, the species may be uninjured even without cover, since, in their prostrate position, they escape the cold and drying winds.

In severe climates, or in the case of tender plants, the tops should be covered with straw, boughs, or litter, as recommended for regular mulch-covers. Sometimes a V-shaped trough made from two boards is placed over the stems of long or vine-like plants that have been laid down. All plants with slender or more or less pliant stems can be laid down with ease. With such protection, figs can be grown in the northern states.

Peach and other fruit trees may be so trained as to be tipped over and covered.

Laid-down plants are often injured if the covering remains too late in the spring. The ground warms up early, and may start the buds on parts of the buried plants, and these tender buds may be broken when the plants are raised, or injured by sun, wind, or frost. The plants should be raised while the wood and buds are still hard and dormant.

_Pruning._

Pruning is necessary to keep plants in shape, to make them more floriferous and fruitful, and to hold them within bounds.

Even annual plants often may be pruned to advantage. This is true of tomatoes, from which the superfluous or crowding shoots may be removed, especially if the land is so rich that they grow very luxuriantly; sometimes they are trained to a single stem and most of the side shoots are taken away as they appear. If plants of marigold, gaillardia, or other strong and spreading growers are held by stakes or wire-holders (a good practice), it may be advisable to remove the weak and sprawling shoots. Balsams give better results when side shoots are taken off. The removing of the old flowers, which is to be advised with flower-garden plants (page 116), is also a species of pruning.

Distinction should be made between pruning and shearing. Plants are sheared into given shapes. This may be necessary in bedding-plants, and occasionally when a formal effect is desired in shrubs and trees; but the best taste is displayed, in the vast majority of cases, in allowing the plants to a.s.sume their natural habits, merely keeping them shapely, cutting out old or dead wood, and, in some cases, preventing such crowding of shoots as will reduce the size of the bloom. The common practice of shearing shrubbery is very much to be reprehended; this subject is discussed from another point of view on page 24.

The pruner should know the flower-bearing habit of the plant that he prunes,--whether the bloom is on the shoots of last season or on the new wood of the present season, and whether the flower-buds of spring-blooming plants are separate from the leaf-buds. A very little careful observation will determine these points for any plant. (1) The spring-blooming woody plants usually produce their flowers from buds perfected the fall before and remaining dormant over winter. This is true of most fruit-trees, and such shrubs as lilac, forsythia, tree peony, wistaria, some spireas and viburnums, weigela, deutzia. Cutting back the shoots of these plants early in spring or late in fall, therefore, removes the bloom. The proper time to prune such plants (unless one intends to reduce or thin the bloom) is just after the flowering season. (2) The summer-blooming woody plants usually produce their flowers on shoots that grow early in the same season. This is true of grapes, quince, hybrid perpetual roses, shrubby hibiscus, c.r.a.pe myrtle, mock orange, hydrangea (paniculata), and others. Pruning in winter or early spring to secure strong new shoots is, therefore, the proper procedure in these cases.

Remarks on pruning may be found under the discussion of roses and other plants in subsequent chapters, when the plants need any special or peculiar attention.

Fruit-trees and shade-trees are usually pruned in winter, preferably late in winter, or in very early spring. However, there is usually no objection to moderate pruning at any time of the year; and moderate pruning every year, rather than violent pruning in occasional years, is to be advised. It is an old idea that summer pruning tends to favor the production of fruit-buds and therefore to make for fruitfulness; there is undoubtedly truth in this, but it must be remembered that fruitfulness is not the result of one treatment or condition, but of all the conditions under which the plant lives.

All limbs should be removed close to the branch or trunk from which they arise, and the surface of the wound should be practically parallel with such branch or trunk, rather than to be cut back to stubs. The stubs do not heal readily.

All wounds much above an inch across may be protected by a coat of good linseed-oil paint; but smaller wounds, if the tree is vigorous, usually require no protection. The object of the paint is to protect the wound from cracking and decay until the healing tissue covers it.

Superfluous and interfering branches should be removed from fruit-trees, so that the top will be fairly open to sun and to the pickers.

Well-pruned trees allow of an even distribution and uniform development of the fruit. Watersprouts and suckers should be removed as soon as they are discovered. How open the top may be, will depend on the climate. In the West, open trees suffer from sun-scald.

The fruit-bearing habit of the fruit-tree must be considered in the pruning. The pruner should be able to distinguish fruit-buds from leaf-buds in such species as cherries, plums, apricot, peach, pear, apple, and so prune as to spare these buds or to thin them understandingly. The fruit-buds are distinguished by their position on the tree and by their size and shape. They may be on distinct "spurs"

or short branches, in all the above fruits; or, as in the peach, they may be chiefly lateral on the new shoots (in the peach, the fruit-buds are usually two at a node and with a leaf-bud between them), or, as sometimes in apples and pears, they may be at the ends of last year's growths. Fruit-buds are usually thicker, or "fatter," than leaf-buds, and often fuzzy. Heading-back the tree of course tends to concentrate the fruit-buds and to keep them nearer the center of the tree-top; but heading-back must be combined with intelligent saving and thinning of the interior shoots. Heading-back of pears and peaches and plums is usually a very desirable practice.

_Tree surgery and protection._

Aside from the regular pruning to develop the tree into its best form to enable it to do its best work, there are wounds and malformations to be treated. Recently, the treating of injured and decayed trees has received much attention, and "tree doctors" and "tree surgeons" have engaged in the business. If there are quacks among these people, there are also competent and reliable men who are doing useful service in saving and prolonging the life of trees; one should choose a tree doctor with the same care that he would choose any other doctor. The liability of injury to street trees in the modern city and the increasing regard for trees, render the services of good experts increasingly necessary.

Street trees are injured by many causes: as, starving because of poor soil and lack of water under pavements; smoke and dust; leakage from gas mains and from electric installation; gnawing by horses; butchering by persons stringing wires; carelessness of contractors and builders; wind and ice storms; overcrowding; and the blundering work of persons who think that they know how to prune. Well-enforced munic.i.p.al regulations should be able to control most of these troubles.

Tree guards.

[Ill.u.s.tration: Fig. 156. Lath tree guard.]

[Ill.u.s.tration: Fig. 157. Wire-and-post tree guard]

Along roadsides and other exposed places it is often necessary to protect newly set trees from horses, boys, and vehicles. There are various kinds of tree guards for this purpose. The best types are those that are more or less open, so as to allow the free pa.s.sage of air and which are so far removed from the body of the tree that its trunk may expand without difficulty. If the guards are very tight, they may shade the trunk so much that the tree may suffer when the guard is removed, and they prevent the discovery of insects and injuries. It is important that the guard does not fill with litter in which insects may harbor. As soon as the tree is old enough to escape injury, the guards should be removed. A very good guard, made of laths held together with three strips of band-iron, and secured to iron posts, is shown in Fig. 156.

Figure 157. shows a guard made by winding fencing wire upon three posts or stakes. When there is likely to be danger from too great shading of the trunk, this latter form of guard is one of the best. There are good forms of tree guards on the market. Of course hitching-posts should be provided, wherever horses are to stand, to remove the temptation of hitching to trees. Figure 158, however, shows a very good device when a hitching post is not wanted. A strong stick, four or five feet long, is secured to the tree by a staple and at the lower end of the stick is a short chain with a snap in the end. The snap is secured to the bridle, and the horse is not able to reach the tree.

[Ill.u.s.tration: Fig 158. How a horse may be hitched to a tree.]

Mice and rabbits.

Trees and bushes are often seriously injured by the gnawing of mice and rabbits. The best preventive is not to have the vermin. If there are no places in which rabbits and mice can burrow and breed, there will be little difficulty. At the approach of winter, if mice are feared, the dry litter should be removed from about the trees, or it should be packed down very firm, so that the mice cannot nest in it. If the rodents are very abundant, it may be advisable to wrap fine wire netting about the base of the tree. A boy who is fond of trapping or hunting will ordinarily solve the rabbit difficulty. Rags tied on sticks which are placed at intervals about the plantation will often frighten rabbits away.

Girdled trees.

Trees that are girdled by mice should be wrapped up as soon as discovered, so that the wood shall not become too dry. When warm weather approaches, shave off the edges of the girdle so that the healing tissue may grow freely, smear the whole surface with grafting-wax, or with clay, and bind the whole wound with strong cloths.

Even though the tree is completely girdled for a distance of three or four inches, it usually may be saved by this treatment, unless the injury extends into the wood. The water from the roots rises through the soft wood and not between the bark and the wood, as commonly supposed.

When this sap water has reached the foliage, it takes part in the elaboration of plant-food, and this food is distributed throughout the plant, the path of transfer being in the inner layers of bark. This food material, being distributed back to the girdle, will generally heal over the wound if the wood is not allowed to become dry.

[Ill.u.s.tration: Fig. 159. Bridge-grafting a girdle.]

In some cases, however, it is necessary to join the bark above and below the girdle by means of cions, which are whittled to a wedge-shape on either end, and inserted underneath the two edges of the bark (Fig.

159). The ends of the cions and the edges of the wound are held by a bandage of cloth, and the whole work is protected by melted grafting-wax poured upon it. [Footnote: A good grafting-wax is made as follows: Into a kettle place one part by weight of tallow, two parts of beeswax, four parts of rosin. When completely melted, pour into a tub or pail of cold water, then work it with the hands (which should be greased) until it develops a grain and becomes the color of taffy candy. The whole question of the propagation of plants is discussed in "The Nursery-Book."]

Repairing street trees.

The following advice on "tree surgery" is by A.D. Taylor (Bulletin 256, Cornell University, from which the accompanying ill.u.s.trations are adapted):--

"Tree surgery includes the intelligent protection of all mechanical injuries and cavities. Pruning requires a previous intimate knowledge of the habits of growth of trees; surgery, on the other hand, requires in addition a knowledge of the best methods for making cavities air-tight and preventing decay. The filling of cavities in trees has not been practiced sufficiently long to warrant making a definite statement as to the permanent success or failure of the operation; the work is still in an experimental stage. The caring for cavities in trees must be urged as the only means of preserving affected specimens, and the preservation of many n.o.ble specimens has been at least temporarily a.s.sured through the efforts of those practicing this kind of work.

[Ill.u.s.tration: Fig. 160. A cement-filled cavity at the base of a tree.]

"Successful operation depends on two important factors: first, that all decayed parts of the cavity be wholly removed and the exposed surface thoroughly washed with an antiseptic; second, that the cavity, when filled, must be air tight and hermetically sealed if possible. Trees are treated as follows: The cavity is thoroughly cleaned by removing all decayed wood and washing the interior surface with a solution of copper sulfate and lime, in order to destroy any fungi that may remain. The edges of the cavity are cut smooth in order to allow free growth of the cambium after the cavity is filled. Any antiseptic, such as corrosive sublimate, creosote, or even paint, may answer the purpose; creosote, however, possesses the most penetrating powers of any. The method of filling the cavities depends to a great extent on their size and form.

Very large cavities with great openings are generally bricked on the outside, over the opening, and filled on the inside with concrete, the brick serving the purpose of a retaining wall to hold the concrete in place. Concrete used for the main filling is usually made in the proportion of one part good Portland cement, two parts sand, and four parts crushed stone, the consistency of the mixture being such that it may be poured into the cavity and require little or no tamping to make the ma.s.s solid. (Fig. 160.)

[Ill.u.s.tration: Fig. 161. A wound, made by freezing, trimmed out and filled with cement.]

"Fillings thus made are considered by expert tree surgeons to be a permanent preventive of decay. The outside of the filling is always coated with a thin covering of concrete, consisting of one part cement to two parts fine sand. Cavities resulting from freezing, and which, though large on the inside, show only a long narrow crack on the outside, are most easily filled by placing a form against the entire length of the opening, having a s.p.a.ce at the top through which the cement may be poured (Fig. 161). Another method of retaining the concrete is to reinforce it from the outside by driving rows of spikes along the inner surface of either side of the cavity and lacing a stout wire across the face of the cavity. For best results, all fillings must come flush with the inner bark when finished. During the first year, this growing tissue will spread over the outer edge of the filling, thus forming an hermetically sealed cavity. In the course of time, the outside of small or narrow openings should be completely covered with tissue, which buries the filling from view.

[Ill.u.s.tration: Fig. 162. Bridge-grafting or in-arching from saplings planted about the tree.]

"It has been found that there is a tendency for portland cement to contract from the wood after it dries, leaving a s.p.a.ce between the wood and the cement through which water and germs of decay may enter. A remedy for this defect has been suggested in the use of a thick coat of tar, or an elastic cement which might be spread over the surface of the cavity before filling. The cracking of portland cement on the surface of long cavities is caused by the swaying of trees during heavy storms, and should not occur if the filling is correctly done.