Kitabı oku: «American Pomology. Apples», sayfa 15
Early spring is a favorite period for pruning, chiefly because it is comparatively a period of leisure; the weather is less inclement than in winter, and the absence of foliage affords us an opportunity to see our work and to anticipate its effects upon the tree. So soon as the buds begin to swell and the foliage to expand, pruning should be arrested, unless in small trees, because the sap is in active motion, and the material called cambium is not yet developed, hence the wounds will bleed, and are not so readily healed over; besides, the bark at this season is very readily separated from the wood, and bad wounds are thus frequently produced by the pruner, which may seriously damage the tree. Then follows a period when pruning had better be suspended until the time that the trees have completed their growth by extension, and formed the terminal bud at the ends of their shoots. The date cannot be given, but it is sufficiently indicated by this mark in nature's calendar; the formation and full development of the terminal bud, and by the copious deposits of woody matter throughout the tree. The annual layer of fibres is then being produced, and the tissues are in the formative stage; the tree now possesses within its own organism the best of all plasters to cure and cover the wounds made by the saw and knife, now the tree possesses the true vis medicatrix naturæ in the highest degree.
A few intelligent nurserymen have learned this very important lesson, and have applied it in the preparation of their trees, for the exposure incident to their removal from the nursery to the orchard. A very few practice it systematically; I knew one, (alas, for the lamented Beeler, of Indiana), who acted upon the suggestion made to him by observations and experiments in vegetable physiology. He left the side branches, though subordinated by shortening when necessary, in order to give stocky stems to his trees, and then removed them with the knife during the summer before they were to be sold and planted, instead of waiting until they were dug and sent to the packing house in the fall or spring. The result was, that while his stems were stout and stocky, they were also smooth, the wounds neatly healed over with new bark, instead of being open from the fresh cuts and liable to crack or bleed, as they would have done had this pruning been deferred until after digging, either in the fall or spring. This may be considered a small matter, but it is an illustration of the principle involved in selecting the period for pruning.
For the removal of small limbs from young trees, hardly any time can come amiss—better to do it out of season than to neglect it, and it is a good rule to have a sharp pruning knife always at hand when passing through our young orchards. There is but one time when pruning is absolutely interdicted, and that is when the wood is frozen. When so circumstanced, it should never be cut nor disturbed in any manner—not even to gratify your best friend, by helping him to a few grafts from your proved tree of some coveted variety. Let him wait for a thaw, or go away without the grafts, rather than commit such an outrage upon your tree: as to approach it with a knife when frozen.
While considering the question of the proper season for pruning, there is one axiom of great importance which should be firmly impressed upon the mind of the orchardist. Much will depend upon which of the two leading objects, above indicated, he may have in view—vigor of growth and symmetry of form, or simply fruitfulness, as the result of his labors in pruning his trees. Pruning at one season will induce the former result, at a different period of the year the same work will conduce to the latter; hence the postulate Prune in winter for wood; in summer for fruit.
CHAPTER XI
THINNING
PROFUSION OF FRUIT-BUDS—WISE PROVISION AGAINST ACCIDENTS—PERIOD OF MATURITY OF PLANTS—MORPHOLOGY—THE YOUNG PLANT GROWS BY DEVELOPMENT OF STEM AND BRANCHES—LEAF BUDS ALL POINTED—THE PERIOD OF ADOLESCENCE VARIES—THE CENTURY PLANT—A DEFINITE PERIOD FOR EACH VARIETY—HOW DIMINISHED OR EXTENDED—STARVING—CROWDING—CUTTING THE ROOTS—OLD OR UNCONGENIAL STOCKS—AT MATURITY AN ACCUMULATION OF NUTRITIVE MATTER—PRESERVING THE BALANCE BETWEEN GROWTH AND FRUITAGE—WE DO NOT THIN FRUIT ENOUGH—TREES EXHAUST THEMSELVES—BIENNIAL BEARERS—ANNUAL BEARERS DESIRABLE—DISBUDDING—FIELD'S HEDGES OF PEARS—REMOVE PORTIONS OF FRUIT—CUTTING-IN THE SHOOTS TO REDUCE FRUIT—DR. HULL AND OTHERS—THINNING THE STRAWBERRY—GOOSEBERRY—GRAPE—THINNING APPLES BY THRESHING THE TREES—BY SEVERE WINTER PRUNING.
Every person who has looked at a bearing fruit tree in the winter season, must have been struck with wonder at the great profusion of fruit-buds with which it was clothed; they are crowded along the slender spray of some varieties as thickly as a necklace of beads, or still more abundantly, like clusters of pearls, they are crowded together upon the little fruit-spurs. We are inclined to cavil at this profusion of nature, and to ask why this waste of vegetative effort. But we may rest assured that it is only another evidence of the unerring wisdom of Him who doeth all things well.
All blossoming and fruiting is but a changed condition of those buds that would otherwise have produced leaves and wood-growth. Every tree, sooner or later, reaches a point which we call its period of maturity, when some of its buds are thus modified. The same elemental parts are still present; but those that were arranged for the production of an elongated shoot, with leaves set around it in some definite manner, and destined for the formation of woody growth, are now so constituted as to have a growth of very short extension, and furnished with modified leaves, so changed, that we scarcely recognize them thus crowded together upon this shortened and modified axis. We here take our first lesson in the very interesting study of morphology, or the science of the changes of form to which the parts of a plant are subjected, in the production of flowers and fruit, from what were otherwise the source of shoots and leaves. This will be found one of the most interesting branches of the study of botany, as it leads us to the investigation of one of the most beautiful displays of Divine power, and, like all such studies, gives us more and more elevated views of the exalted wisdom and benevolence of an All-wise Creator, who has produced nothing in vain, and who, while creating worlds and systems of the greatest magnificence, has condescended to prepare the most tiny flower, and its previous bud, in the most perfect manner.
The study of morphology which gives us such an insight into the mechanism of the plant, and which leads us into such mazes of wonder and admiration, cannot now detain us further than to be named and referred to as the explanation of the formation of what we call fruit or blossom buds. The reader is referred to the full explanations of this subject by the famous philosopher and poet, Goethe; or, if more conveniently accessible, to his English translators, or to the appropriate chapters in any of the modern text books of botany.
When the plant is young, its chief object is to grow; it must acquire size and development, to enable it to produce and bear up the enormous crop it is destined one day to yield. Hence in the early years of a tree there is none, or very little of this transformation of the buds, which are all of the pointed character, and when excited into growth, they all produce shoots and leaves only, which result in the formation of an increase of the woody fabric, that we call the tree. This period of adolescence is longer or shorter in different species and varieties—in some it may extend through many years. Thus, the American Aloe is called the Century Plant, from the common belief that it must survive a hundred summers before this stage of maturity and blossoming is reached; whereas this plant only needs a period of thirty years or less to produce its blossoms, when it is favorably situated as to soil and climate.
There is, it is probable, a definite period at which each kind of plant will have these changes occur in the buds, when they will begin to flower and to produce fruit. This period may be accelerated or retarded, to some extent, by human means; for we have observed, that whatever produces excessive vigor, is attended with the formation of leaf buds; whereas, all those conditions and circumstances that check the vigorous growth by extension, provided they do not too greatly impair the vitality of the plant, will conduce to the formation of flower-buds.
Some of these conditions consist in starving the tree, or by planting it in a sterile soil, that has deficient moisture; by severely crowding the roots, or by cutting them, as in root pruning; in grafting a portion of the young plant upon an old or an uncongenial stock, or one that is naturally dwarfish; in ringing the bark; in frequent transplanting, or in continued summer pinching; in short, almost any circumstances which appear to threaten the life of the tree, seem to excite within it an effort for the preservation and perpetuation of the species, by changing the bud plants, attached to the parent, into seed plants, that may and will be separated from it to reach the soil eventually, and there to establish an independent existence.
As the tree advances in growth, and approaches toward its natural period of maturity, it is supposed that there is an accumulation of nutritive matter within it, and at the same time the roots will have exhausted the soil, to some extent, of the elements that contributed to the production of wood-growth, and the result is the formation of flower-buds. Now it becomes a nice matter to preserve the proper balance between these two systems of growth, the wood producing and the fruit forming. Two opposite systems of production have become established in the tree, the one infertile, the other producing the desired fruits; the one preserving the health and vigor of the tree, the other tending to preserve the species at the same time that it satisfies our demands for fruit, but also meanwhile tending to the destruction of the tree, for all old trees are apt to overbear. Young trees, on the contrary, in which the vigor of wood-growth remains in full activity, very often produce fruit-buds and blossoms, but do not perfect their fruit, which either fails to set, from some imperfection of the organs of reproduction, or falls prematurely, in consequence of the wood system absorbing the nutriment, or failing to prepare the proper juices for their support. Trees, in these different conditions, require an entirely opposite treatment. The younger need summer pruning and pinching, to check their too great vigor, and to develop the laterals or spurs with their blossom buds; the older need winter pruning, for the double purpose of reducing the amount of fruit, and also to excite renewed vigor in the production of wood growth that shall take the place of that which has been removed. This subject will be more appropriately discussed in another chapter, to which the reader is referred; while we proceed to the legitimate topic of thinning fruit.
Thinning fruit is not practiced as it should be, particularly on the apple; old trees are often too fruitful, so much so as not only to deteriorate the fruit, but to injure the tree itself. This is so much the case with certain varieties, as to constitute a serious objection to planting them; other sorts so exhaust themselves by over-production in one season, as to be barren, or nearly so, the next year, during which period of rest they are able to recuperate their energies and to provide a new set of flower-buds. These are called biennial bearers, and such are quite numerous in our orchards. Those kinds that are prone to overbear every year, are often objectionable on account of the diminished size and inferior character of their fruits, which result from this cause, particularly when the trees have become old. The great desideratum, especially with those who object to the trouble of thinning the fruit, is to find a variety that will produce an even or well distributed, continuous, and moderate yield—an annual bearer, that does not exhaust itself by the production of one enormous crop so as to require it to rest and recuperate. Such varieties are to be found in our collections, and should be highly prized.
But to return to our topic, the bold method of reducing the crop by winter pruning, has already been alluded to, and is highly recommended for such old trees as have ceased producing thrifty shoots of wood-growth at their tips, and have taken on an excessive tendency to fruitage. There are other methods of producing this desired effect, diminishing the amount of fruit when excessive, and thereby greatly enlarging the size, and improving the flavor of that which is left behind: some of these will now be mentioned.
Disbudding.—One of these consists in the removal of alternate buds, or even a greater proportion than one half; this may be performed either in the end of winter or in early spring, or even after the buds have pushed, still later in the season. This work may be done with the fingers, a knife, or by using the shears, when the buds are terminal, as in old bearing apples and pears, or on some cherries. This plan has been practiced with very good success upon the Duchesse pear, by T.W. Field, who accidentally had his attention directed to the feasibility of making this variety very productive. He had observed that certain trees, which were rubbed so by the cart-wheels as to be stripped of a portion of their buds in the winter season, instead of being injured thereby, were more productive than those which retained all of their abundant spurs and blossoms, and which, nevertheless, often bore sparsely. Improving upon this hint, he has since planted some such varieties in close rows or hedges, which he trims annually with the shears to keep them within bounds, and at the same time to diminish the amount of blossoms. Disbudding is systematically pursued in the European fruit-gardens, and we have elaborate directions for the season and mode of performing the operation, which is extensively practiced, particularly on the trees that are grown as espaliers, and those kept in orchard houses. If neglected, the trees become exhausted by over-production; and the failure of production by the fruit-spurs which results, causes vacant spaces upon the tree, which are afterward, with difficulty, restored to a profitable condition.
Another method, and the one usually pursued by those who practice thinning, is, to go over their trees after blossoming, while the fruit is still small, and systematically remove such a proportion as they may deem sufficient to relieve them of the surplus; and while so doing, they select for removal all the inferior specimens. This is found to pay very well in the increased size, appearance, and flavor of those that remain, and is practiced by all good horticulturists.
It is found in some varieties that the thinning may be done when the fruit has attained to one-half its usual size, so that it may be marketed, and yet those which are left, will swell out to their full proportions after this removal, and will realize, when harvested, more money, and will even be of greater weight than if the whole crop had been left upon the tree until its natural period of maturity. The reason is obvious, and depends upon the greater size and fuller development of the fruit, which remains after thinning.
Summer Pruning has already been alluded to as one of the methods of producing fruitfulness. When it is here introduced as a means of thinning the fruit, the recommendation may appear somewhat paradoxical—yet it is not so. Neither is this cutting a parallel operation to that in which we seek to check the excessive vigor of young shoots by pinching and heading-in, with a view to directing the sap to the lateral buds so as to cause their development for the formation of fruit-spurs, which will insure a greater production of fruit: whereas this summer pruning removes a portion of the crop to be supported by the tree. This plan is most successfully practiced by judicious orchardists, among whom may be named Dr. Hull, of Alton, Ill., who has thus treated his peaches, nectarines, and plums. This process consists in cutting off the ends of the shoots that are laden with fruit, while these are yet quite small; the superabundance is thus removed in a great degree by the knife, and the excess of foliage is also diminished so as to expose the fruit freely to the sun and air, which insures an increased size and heightened color, particularly to the peaches and nectarines. The remaining fruit is also suitably thinned so that no specimens shall crowd one another. The exact distances between them must be determined by the judgment of the operator; some have decided that peaches should not be nearer than nine inches; plums and nectarines may be separated by a smaller distance; but it is not easy to lay down a precise rule.
Thinning is not often practiced upon the strawberry crop, which appears able upon suitable soils to produce a great abundance of fine fruit, but it may be done by the curious, and enormous show specimens, such as are often exhibited at fairs, are produced by special care and high manuring, aided greatly by judicious thinning; not only by cutting back a portion of the crowns, so as to throw the whole force of the plant into one or two trusses, but still further, by removing with the scissors a portion of the blossoms or fruit, so that the few which are left may become enormously distended with the nutriment that had been stored up in the plant for a much greater number. Some may consider this one of the tricks of the trade, and so it is when merely done for the sake of deceiving the public, who are asked to purchase the variety by the sample of fruit, without detailing the arts by which the results were accomplished: but there can be no objection raised against such practices when pursued by the amateur for the sake of producing unusually large fruits of any variety.
The English pursue a similar method with their show gooseberries; by means of thinning and high feeding, with great attention to watering, these fruits are made to assume gigantic proportions that are little dreamed of by cultivators of the smaller varieties, which are chiefly grown in this country.
The grape is very prone to over-production, and the crop, as well as the vine itself, is often much injured by a want of attention to this particular. So avaricious is man, that few persons will exert the needed firmness and perseverance to remove the excess which the beautiful vine annually affords. The result of this neglect is apparent at the vintage, especially when from any fault of the season, or from the invasion of insects or of mildew, the foliage may have been damaged, as it frequently is, to a considerable extent. Then we find large quantities of the grapes so deficient in color and flavor as to be worthless; in some varieties whole bunches will hang flaccid, withered, and insipid—while perhaps a few, more favorably situated, will have their proper flavor. The grape vine is well called beautiful, and it is capable of sustaining most wonderful amounts of fruit; but on young vines, especially, it is very bad policy to allow of this over-production.
The tendency to fruitage may be met in different ways, a few of which will now be pointed out, and all planters are urged to observe and to practice some of these plans for reducing the exuberance of this kind of fruit. In the first place we practice winter pruning, regardless of its established and well-known effect of producing an increase of wood-growth, for this is what we desire to obtain in the vine, on account of its habit of yielding its fruit on wood of the previous year's growth; by this means we are able to pursue the renewal system, which is so generally preferred, and thus we may keep our vines perpetually clothed with new wood, or canes as they are technically called. By this winter pruning we can reduce the amount of wood that is of a bearing character, to any point which may be deemed desirable, according to the strength and age of the vine, and thus the crop is thinned by a wholesale process of lopping off the superabundance of buds, that would have produced an excess of fruit. Another method of thinning is, to rub out a portion of the shoots, this may be every alternate branch in close jointed varieties of the vine: this is to be done soon after the buds have burst, and while the branches are yet quite small, so that the vital forces may be directed to those that remain. Wherever double shoots appear, the weaker should always be removed.
Still another method of reducing the superabundance, remains to be noticed; this consists in thinning the grapes themselves, the separate berries, which, in some varieties, are often so crowded upon the bunch, as to prove a serious injury to one another. In hardy out-door culture this is seldom practiced, being less necessary than in the large varieties of foreign grapes that are grown under glass. These are systematically thinned with the scissors, so that none shall crowd together; and this process, repeated from time to time, is found to produce much finer and larger berries and heavier bunches than when all are left.
A very rude method has sometimes been pursued in thinning the superabundance of fruit upon apple trees. It appears so very Gothic that its description may only excite a smile, when it is stated that it consists in threshing the tree with a long slender pole, by which a portion of the fruit is cast to the ground. Rude and primitive as this method may appear, it is surely better than no thinning at all, and is attended with this good result, for which it deserves some commendation; the threshing removes portions of the excessive twiggy spray that always abounds upon such trees as those under consideration, and thus, in a degree, it prevents the recurrence of so heavy a crop the following year. Whenever an old orchard has reached this condition of over-fruitfulness, however, the best method of thinning is to give a severe winter pruning; removing portions of the spray and encouraging the free growth of young wood in various parts of the top, to replace the older portions that were removed.
