Dwarf Fruit Trees

NURSERY MANAGEMENT

Dwarf trees are managed in the nursery very much the same as standards of the same varieties. There are no special points to be observed except in the formation of the tops. Western New York nurserymen, who now grow the principal supply of dwarf apple and pear trees, have the custom of forming their nursery stock with high heads. That is, the heads are formed at a height of eighteen inches to three feet from the ground. In this matter the pattern is taken after the usual style of standard trees. This is quite wrong. Of course, some planters might like to have dwarf trees with trunks two or three feet tall, but the best form has a much shorter stem. At any rate the buyer of dwarf trees ought to be at liberty to form the head within three or four inches of the ground if he so desires. This becomes very difficult if the tree is once pruned up to a height of two or three feet.

In order that the planter may reach his own ideal perfectly in this matter, it is sometimes necessary to buy one year old trees, what the English nurserymen call maidens. This, of course, enables the tree planter to form the head wherever he desires.

IV
PRUNING DWARF FRUIT TREES

The pruning of dwarf fruit trees is a matter of the greatest consequence, for on proper pruning depend both the form and the productivity of the trees. Some of the details of management will be explained in the succeeding chapters, dealing with the particular kinds of fruits, but a few general statements should be set down here.

1. The trees are severely headed in. This applies more particularly to bush and pyramid forms. By the term "heading in" we refer to the shortening of the leaders. Such shortening is usually given at the spring pruning, while the trees are dormant. The leaders may be headed in at times, however, during the latter part of the growing season, in July. Such stopping of growing leaders will be practised more often on young trees just coming into bearing than on old trees. (Fig. 10). Constant heading back of some sort, however, is required in nearly all cases, if the tree is to be retained in its dwarf form. The mistake has often been made of thinking that a tree propagated on a dwarf root would take care of itself.

2. Summer pruning is essential. In most American orchard practise one annual pruning (sometimes one pruning every five years!) is considered sufficient, and systematic summer pruning is seldom or never given. Now summer pruning tends much more to repress the growth of a tree than winter pruning does. In fact, heavy winter pruning leads rather to increased vegetative vigor. Aside from any special system of pruning, therefore, this rule is to be remembered, that summer pruning is desirable, on general principles, for dwarf fruit trees.

FIG. 10—BUSH APPLE, THREE YEARS OLD

Showing strong leaders formed during the summer

3. Side shoots usually need pinching during the growing season. Leaders are more frequently allowed to grow unchecked throughout the season, or are stopped only late in their period of development. In the pomaceous fruits, which form distinct fruit spurs, the checking of these side shoots helps toward the production of fruit buds. As long as every bud is allowed to push out into a strong shoot no fruit spurs can become established. Thus the summer pinching of the side shoots on apples and pears has the purpose of encouraging the formation of fruit spurs. On peach and plum trees equally distinct fruit spurs do not form; but if the side shoots are allowed to push forth unrestricted they are apt to choke one another. There will be too many of them, they will not get light enough, their growth will be weak and sappy, and they will not form fruit buds. Good fruit buds on a peach tree, for example, form on strong, clean, healthy shoots of this year's growth for next year's crop of fruit. It is seen, therefore, that in nearly all sorts of dwarf fruit trees the summer pruning is especially directed to the suppression or regulation of the growth of side shoots.

This part of the treatment becomes of prime importance in dealing with cordons and espaliers.

4. The control of the fruit spurs or of the side shoots here contemplated requires that the trees be gone over more than once during the growing season. In fact, four successive examinations of the tree are usually required. Old trees can sometimes be managed with two or three, but young ones, on the other hand, will sometimes require six or more. Of course, there are usually only a few shoots that need attention at each succeeding visit, and the work can be very rapidly performed. The first pruning, or pinching, falls about three weeks after the trees have started into growth. The next one comes ten days later, the next one ten days later again, and the fourth pruning two weeks after the third. From this time onward the intervals lengthen. These specifications, of course, are only approximate and suggestive. Some judgment is required to select just the proper moment for pinching back a shoot and even more to select the time for a general summer pruning. Those trees which enjoy the sympathetic presence of the gardener every day are sure to fare best. The bulk of this pruning can be done with the thumb nail and forefinger, but I find a light pair of pruning scissors pleasanter to work with.

5. Root pruning is sometimes advisable. Since the whole program is arranged to check the growth of the dwarf tree, root pruning would naturally fit well with the other practises recommended. Root pruning checks the growth of a tree about as positively as any treatment that can be devised. When dwarf pear or apple trees seem to be making too much wood growth and not enough fruit, they can be taken up, as for transplanting, during the dormant season and set right back into place. This digging up and replanting is always accompanied by some cutting of roots. The whole root system is disturbed and has to re-establish itself before the top vegetates very strongly once more. Such root pruning ought to be done late in the fall. It is a special practice, suited to refractory cases, and the gardener is not recommended to indulge in it too freely.

6. A certain equilibrium between vegetative growth and fruit bearing should be established at the earliest possible moment, and should be maintained thereafter. Of course, some such equilibrium is sought in the management of a standard tree; but it is secured earlier in the life of the dwarf tree and should be much more accurately maintained. The tree must make a certain amount of growth each year, but this must be only enough to keep it in good health, and to furnish foliage enough to mature the fruit. Beyond this wood growth the tree should bear a certain amount of fruit every year, for annual bearing is not only an ideal but a rule in the management of dwarf trees. This equilibrium once established must be maintained not by haphazard pruning, but by some suitable system. If there is the proper balance between summer pruning and winter pruning, combined with proper control of cultivation and fertilization, then the balance between vegetation and fruitage can be kept up. It is a delicate business, like courting two girls at once, but it can be carried out successfully.

7. The training of trees into mathematical forms is largely a mechanical process. For the most part the trees are shaped while they are growing. The young shoots are twisted and bent to the desired positions, and are tied into place until the stems become hardened. There are many clever little tricks for expediting this sort of work and for making the results more sure, but a rehearsal of them here would be tedious. The most important rule to remember is that constant attention must be given the shoots while they are growing. Mistakes are corrected with difficulty after an undesirable form has been allowed to harden.

V
SPECIAL FORMS FOR TRAINED TREES

We have already explained the connection between dwarf trees and the practise of training them in special forms. It is true that this practise looks childish to American eyes. It seems to be only a kind of play, and a rather juvenile sport at that. Nevertheless we should understand that in some parts of the world it is a real and profitable commercial undertaking. We should consider also that in other places, where fruit of very high quality is better appreciated, perhaps, than it is in America, the extra trouble is thought to be worth while for the superior quality which it gives the fruit. As this matter is coming to be of more importance in America also, and as the interest in amateur fruit growing is enormously increasing, we may fairly begin to talk about these methods.

The formation of trees into bushes and pyramids, by means of systematic pruning according to a definite plan, as explained in the succeeding chapters, while apparently simpler and more reasonable to our American eyes, it is still a method of training the tree. The fruiting branches are placed at definite points and the fruit spurs are encouraged to grow in regular succession. It is not a very great step from this to a distribution of the branches into a more precise form.

The different forms which are used most commonly are named and classified in the following outline:

A.—Forms of three dimensions:

a. Vase or bush

b. Pyramid

c. Winged pyramid, etc.

B.—Forms of two dimensions:

a. Various espaliers

b. Palmette-Verrier

c. Fans or Fan-espaliers

d. U-form and double U-form

C.—Trained to a single stem:

a. Upright cordon

b. Oblique cordon

c. Horizontal cordon

(with one arm)

(with two arms)

d. Serpentine cordon, etc.

Among the forms of three dimensions none is of much practical importance besides the pyramid and bush or vase form. These are sufficiently explained in the chapters on pears and apples. Here we need only to define them. The pyramid tree is one which has a straight central stem with branches radiating therefrom. It is especially adapted to upright growing varieties of pears. The bush or vase form has several main arms or branches, all standing out from approximately the same point and growing upward at a more or less acute angle, thus forming roughly a vase. The secondary branches put out from these, bearing fruiting wood, as the gardener may order.

FIG. 15—PEARS IN DOUBLE U-FORM

From Loebner's "Zwergobstbäume"

The flying pyramid or winged pyramid, described in all European books, is considerably different from the ordinary pyramid and is more precise in its design. Usually six arms are brought out at the base of the tree. These are grown in a direction approximately horizontal until they reach a convenient length,—say two to three feet. They are then suddenly bent upward and inward and are conducted along wires set for this purpose until they meet in a common point with the main stem of the tree some four to eight feet above where the branches put out. There is thus formed a precise mathematical pyramid. Along these main arms fruiting spurs are allowed to grow, but no branches are expected to develop.

Sometimes the flying pyramid is made more elaborate by bending the arms into a spiral form. Other more or less complex modifications are practised to some extent. All of them are to be regarded merely as curiosities and as of no practical value.

The various forms of espaliers and fan-shaped trees have their special and legitimate uses. It may be said here that the Palmette-Verrier is regarded generally as being the most successful for the largest number of varieties of fruits. It is a safe rule also that the simpler forms are generally the better. With rare exceptions a tree confined to a moderately small space is more satisfactory than one trained over a large space.

Great care must be exercised in forming these trees. If the geometrical style of training is undertaken at all, it should be carried out with considerable precision. If one arm happens to be placed a little higher, or at a little more moderate angle, or otherwise more favorably than the corresponding arm, it will very soon divert to its own use the major portion of food supplied by the top. It will outgrow its mate and the form which the gardener designed will eventually be lost. It will be seen at once that this condition makes the same care and precision necessary in all forms of training.

Fig. 16—PEARS IN U-FORM

Sometimes called two-arm upright cordons

The U-form classifies somewhere between the cordon and the espalier. It consists of two upright branches joined to a single trunk below by an arc of a circle. The fruit is all borne on the two parallel stems which are treated essentially the same as upright cordons. (Fig. 17.)

The double U-form is made by growing two U's from the same tree. The stem is first divided near the ground into two branches and each of these is immediately divided into two more. The tree thus provides four parallel and equally spaced upright and fruiting stems equal to four upright cordons, except that they are all supported from a single trunk. The U- and double U-forms are employed mostly for plums, apricots, peaches and nectarines.

One occasionally sees much more elaborate schemes of training than any here mentioned. There are complex geometrical designs, even pictorial figures—birds, dogs, and beer-steins—and sometimes the initials of the gardener, or the name of his kingly and imperial majesty. In every case the method of producing these forms is practically the same. A frame is built of wood or wire in the form which it is desired to give the tree. Branches are developed at suitable points on the tree and these are tied out while they are growing to the wooden or metal form. It does not require any special care or ingenuity to produce the most elaborate designs in this method. It is essentially a job of carpentry.

FIG. 17—APRICOTS IN U-FORM

We come now to the cordons. If we take the simplest form, namely the upright cordon, we have what we may call a tree of one dimension only. The upright cordon has nothing but height, eschewing both breadth and thickness. A cordon is simply a tree trained to a single stem and this stem may be placed in any position. The position or direction of the stem classifies the cordon. There are, therefore, besides the upright cordon, others which are oblique, that is, which make an angle with the horizontal, those which are horizontal, and those which are bent into various forms. The serpent form is one of the simplest of these. This form of cordon is simply bent back and forth against a trellis forming a series of S's one above another. The horizontal cordons are of two varieties, namely one-arm and two-arm forms. It is altogether a matter of convenience which one of these forms is chosen.

FIG. 18—PEAR IN ESPALIER

This tree is carrying over 200 fruits

In conclusion it may be pointed out that the slower growing trees, pears and apples, are the better suited to the more elaborate forms of training. The more free and rapid growing species, such as peaches, nectarines, cherries, and Japanese plums, are better managed in somewhat simpler forms, preferably the fan. Such trees do well, however, in the U-form or double U-form.

FIG. 19—OLD ESPALIER PEARS ON FARM HOUSE WALL