The Nursery Orchard, as practiced by A.R. Whitney, of Lee Co., Ill., now one of the largest orchardists of the country, is well worthy of imitation by all those nurserymen, who desire also to become fruit-growers. In laying off the blocks of nursery stock, the varieties that are wanted for the orchard, should be planted in such a manner, that they shall be in every fourth row, so that the orchard trees will stand in rows sixteen to twenty feet apart, according as the nursery-rows are four or five feet wide. In cultivating and trimming these rows in the nursery, a plant is selected, every twelve or sixteen feet, which is to remain as the orchard tree when the block shall be cleared. A good tree is selected, and special care in the pruning is bestowed upon it to secure the desired form, and low branches; if necessary, the tree on either side of it is removed, to give it room. By the time the block is cleared, these orchard trees are often in bearing, and while his customers are struggling to save their trees, and nursing them after their transplanting, the nurseryman will have become an orchardist, and is enjoying his fruits. The nursery will have become an orchard—one rather closely planted to be sure—but the trees can be dwarfed by root pruning with the plow, they shelter one another from the prairie blasts, and when too thick, alternate trees may be removed to the wood-pile, and thus cheer the owner on a winter's day.
Winter-killingis a serious evil in the nursery, as by it whole rows and blocks of certain varieties are sometimes destroyed, or very seriously injured. It has been observed to be most marked in its effects upon those sorts of trees that make the most vigorous and sappy growth,and those which continue to grow late in the season. Such varieties have very naturally acquired the epithet oftenderespecially as orchard trees of the same kinds, even in a bearing state, have been similarly affected; in some sections of the country, these kinds have been thrown out of cultivation. The bark looks shriveled and withered, the twigs seem dry when cut, and resist the knife; when thawed by the fire, or on the return of spring weather, the bark seems loose, and the inner bark, instead of being greenish-white, becomes brown, and the whole tree looks as though it was dead. In old trees, large portions of the bark start from the stem and large limbs, and hang loosely for awhile and then fall off. The buds alone retain their vitality, and upon the return of spring they sometimes succeed in establishing the necessary connection with the soil, and restore the circulation of the sap; the results are the deposit of the usual annular layer of woody matter, which encases the dead portions within, that become like asequestrumof dead bone in an animal. The best treatment for the trees that have been winter-killed, is to cut them back very severely, in the hope of producing a vigorous wood-growth the next season, to repair the injury.
A partial winter-killing often affects small nursery trees, especially on low and wet, undrained soils; the plants recover, but for years they have a black point in the heart which embraces all of the wood-growth that was affected—all their wood at the period of the disaster. This is enclosed and surrounded by clear, healthy wood; but such trees are not desirable, they are so fragile, as to be easily broken.
The best preventive for winter-killing in the nursery, isto encourage early ripening of the wood, and to drain the land, is one of the best means of producing this effect; another is the cessation of culture at mid-summer, and the sowing of oats very thick at the last cultivation, has been practiced, and, it is thought, with excellent effects. The rank growth absorbs the superfluous moisture, robbing the trees, and afterwards forms a good protective mulch during the winter. The objections to it are, that it encourages the mice, which, by girdling the trees, effectually winter-kills them.
Many nursery and orchard trees often present a black discoloration of the bark, which is quite unsightly, and excites alarm for the health of the tree. This is often caused by trimming at unfavorable periods; in the spring pruning of bearing trees, the large stumps sometimes bleed, but in the nursery trees it arises from cutting them, and especially in the barbarous trimming up, during severely cold weather, when they are frozen.
Injurious Animals and Insects.—The nurseryman sometimes suffers from the depredations of some of the smaller animals, which cause him great annoyance. The mole, though highly recommended by the naturalists as a harmless beast, who is an aid to horticulture by his insectivorous habits, is nevertheless injurious in hisways; for he often makes his run in the seed bed, or along a row of root grafts, and raising them from their stations break their tender rootlets, when the sun and air soon destroy them. Mice, of different kinds, are still more destructive, particularly in the winter, when they will often girdle young trees near the collar, and do much mischief. They also devour many seeds after they have been committedto the ground, particularly those sown in the autumn. For both of these animals, the best preventive is to catch them, which may be done with traps. They may also be poisoned. The young trees may be protected from the mice by keeping them clear of rubbish, that would shelter these animals, and when snow falls, it should be trodden down closely about the trees. Owls and cats will do their share in the destruction also, but they will also take the friendly little birds.
Rabbits are also very apt to bite off young shoots, and to bark trees of larger growth in the nursery, as well as those that have been set out in the orchard. Various methods have been suggested to prevent their injuries. Wrapping the stems with strips of rags or with ropes of hay, was formerly the method practiced by those who wished to save their young trees; the process is tedious and troublesome. A few pieces of corn-stalk have been placed by the stem of the tree and tied to it; this, too, is a troublesome procedure, though, like the others, it is efficacious. A still better plan in this class of preventives, is a half sheet of common brown wrapping paper, made to encircle the stem, like an inverted funnel; this need be fastened only at the top, by a little thin grafting wax applied with a brush at the instant, or the paper may be tied with some common white cotton string. This envelope keeps off the rabbits, and lasts through the winter; the string will decay before the growing season returns, so there is no danger of strangulation. All the other wrappings must be removed, or they will injure the trees and afford harbor for insects. It will be observed that all applications of this class, are adapted only to trees thathave a clean hole without branches, but are not suited for those which are made to branch at or near the ground. Besides, in countries where snow abounds, these little marauders are elevated above the wrappings, and have fair play at the unprotected parts of the tree—on this account another class of preventives has been adopted.
These consist in applications that are obnoxious to rabbits, which, being nice feeders, are easily disgusted. White-wash, and white-wash made with tobacco water, soap, whale-oil soap, grease, blood, and especially the dead rabbit itself, freshly killed, have all been used with happy results, in that they have driven these animals to seek their food elsewhere. A very good application, and one that may be used upon a low-branched tree as well as to the smooth clear stem of one that is higher, is blood. This is put on with a swab; a few corn husks tied to a stick, answers very well. Dipping this into the vessel of blood, the swab is struck gently against the stem or the branches, as the case may be, and the fluid is spattered over it. A very little will answer to keep the rabbits away, and the effect will continue all winter, notwithstanding the rains.
Certain insects also prove injurious in the nursery, among these the most numerous are theaphides, which are found upon the roots of some fruit trees, especially the apple. Others of this disagreeable insect appear upon the foliage, among these one of the most disgusting is the one which causes the black curl, on young cherry trees. The pear tree slug, (Selandria cerasi), destroys the foliage of many young trees in the nursery; caterpillars also do their share of mischief. A serious trouble in oldnursery grounds, especially where manure is used, is the grub of the May beetles, of which there are several species. These grubs are whitish, nearly as thick as the little finger, with a brownish head. They cut off the young nursery trees at three or four inches below the surface. We have seen two-year old stocks cut in this manner, and the work of destruction was so complete, that the proprietor of the nursery was a long time in attributing it to such an apparently inadequate cause as this sluggish, soft-bodied grub. All of these, with other insects injurious to fruit, will be considered in their appropriate place.
[12]The Plant, a Biography: M.J. Schleiden, p. 68.
[12]The Plant, a Biography: M.J. Schleiden, p. 68.
[13]Because it had no root, it withered away. Mat. 13, 6.
[13]Because it had no root, it withered away. Mat. 13, 6.
[14]Du Breuil, Culture of Fruit Trees; English Translation.
[14]Du Breuil, Culture of Fruit Trees; English Translation.
[15]A.R. Whitney, Franklin Grove Nurseries, Lee Co., Ill.
[15]A.R. Whitney, Franklin Grove Nurseries, Lee Co., Ill.
DEFINITION OF—OBJECTS—EARLY FRUITAGE—DEFINITION OF TERMS. DWARFING STOCKS—OTHER MEANS OF DWARFING—DWARFS AND STANDARDS. PYRAMIDS OR CONICAL—ESPALIERS—LAYING BARE THE MAIN ROOTS IN SUMMER, TO DIMINISH THE VIGOR OF THE TREES—REMOVING A PORTION OF THEM—ROOT-PRUNING—TRANSPLANTING—EUROPEAN ESPALIERS AND WALL FRUITS—DU BREUIL'S CORDONS—CROWDING, AS A MEANS OF DWARFING—PINCHING, TWISTING, AND FRACTURE—FIELD'S PEAR HEDGES—OUR CLIMATE DOES NOT REQUIRE THESE MEANS OF TORTURE—FACILITY OF PROTECTION MAY RENDER THEM DESIRABLE—GENERAL INTRODUCTION OF QUINCE-DWARFED PEARS IN THIS COUNTRY—MANY FAILURES—SUCCESS DEPENDS UPON CARE—FRENCH SUCCESS—CHINESE—UNCONGENIAL STOCKS—IMPERFECT UNION—PINCHING—HIGHEST PERFECTION OF THE ART OF HORTICULTURE—EQUALIZE THE FLOW OF SAP—NATURALLY FLOWS TO HIGHER PARTS AT EXPENSE OF LOWER, MAY BE REGULATED BY TRIMMING—BY DISBUDDING—BENDING DOWN—PINCHING THE STRONGER, AND ENCOURAGING THE WEAKER—ILLUSTRATION IN THE STRAWBERRY—DWARFING THE APPLE—PARADISE STOCK—THE DOUCIN; UNFIT FOR ORCHARDS—ROOT-PRUNING—HOW IT OPERATES—TIME TO BEGIN—HOW TO BE PURSUED—SEASON FOR—EXPENSE—ROOT-PRUNING PLOW.
DEFINITION OF—OBJECTS—EARLY FRUITAGE—DEFINITION OF TERMS. DWARFING STOCKS—OTHER MEANS OF DWARFING—DWARFS AND STANDARDS. PYRAMIDS OR CONICAL—ESPALIERS—LAYING BARE THE MAIN ROOTS IN SUMMER, TO DIMINISH THE VIGOR OF THE TREES—REMOVING A PORTION OF THEM—ROOT-PRUNING—TRANSPLANTING—EUROPEAN ESPALIERS AND WALL FRUITS—DU BREUIL'S CORDONS—CROWDING, AS A MEANS OF DWARFING—PINCHING, TWISTING, AND FRACTURE—FIELD'S PEAR HEDGES—OUR CLIMATE DOES NOT REQUIRE THESE MEANS OF TORTURE—FACILITY OF PROTECTION MAY RENDER THEM DESIRABLE—GENERAL INTRODUCTION OF QUINCE-DWARFED PEARS IN THIS COUNTRY—MANY FAILURES—SUCCESS DEPENDS UPON CARE—FRENCH SUCCESS—CHINESE—UNCONGENIAL STOCKS—IMPERFECT UNION—PINCHING—HIGHEST PERFECTION OF THE ART OF HORTICULTURE—EQUALIZE THE FLOW OF SAP—NATURALLY FLOWS TO HIGHER PARTS AT EXPENSE OF LOWER, MAY BE REGULATED BY TRIMMING—BY DISBUDDING—BENDING DOWN—PINCHING THE STRONGER, AND ENCOURAGING THE WEAKER—ILLUSTRATION IN THE STRAWBERRY—DWARFING THE APPLE—PARADISE STOCK—THE DOUCIN; UNFIT FOR ORCHARDS—ROOT-PRUNING—HOW IT OPERATES—TIME TO BEGIN—HOW TO BE PURSUED—SEASON FOR—EXPENSE—ROOT-PRUNING PLOW.
Dwarfing consists in so controlling the growth of plants as to reduce the natural size of any of our fruit trees, and bring them within comparatively narrow bounds. The objects of dwarfing are to enable us to planta large number of specimen trees, or of varieties upon a small piece of ground, or to have small trees beside the alleys of our gardens. Such plants are also well adapted for growing in pots, or in the borders of an orchard-house. It is claimed for dwarfed trees, that they are more prolific than those which are worked on free stocks, which are often erroneously called standards, and it is also asserted that these dwarfed trees will bear sooner and produce finer and larger fruit.
The terms used may as well be explained at once. When we speak of dwarfing stocks, we mean such as are so uncongenial as to check the wood-growth; and thus, while producing smaller trees, they have a tendency to early fruitfulness if properly managed. But this condition may be superinduced by other means than these. Hence in speaking of dwarf pear trees, it does not follow that they have been worked on the quince or other uncongenial stock. A dwarf tree, of whatever kind, is simply one that has been caused to assume diminutive proportions. Dwarfing stocks are contrasted with free stocks, or those which would have attained the full size of the species, and which, when grafted, produce large trees. These are often mis-called standards, when contrasted with those that have been worked on the quince, or other dwarfing stock. Whereas, the trees propagated on free stocks, may also be dwarfed, by means that will be presently detailed; and the term standard refers really to the mode in which the training of the specimens has been performed. Those which are trimmed up as orchard trees are usually treated as standards, and are said to be trimmed to standard hight. Those branching at a lower point are calledhalf standards. Those which are branched so low as to conceal the stem of the tree, and in which the limbs are so well managed that the lower ones are always the longest, and those above them gradually contracted to the point at the top, are called pyramids, or more properly conical trees. Whether dwarfed or not, trees may be trained in a variety of forms, such as the columnar, sometimes called thequenouille; the vase or goblet form may be given them, or the parasol shape, and they may be made to assume the form of a fan or other mode of extension laterally, when trained upon a wall or espalier frame, as may be seen in the illustrations given by Du Breuil; but it is seldom that our gardeners are willing to bestow the care and attention necessary to produce these results.
The vertical and obliquecordonsrepresented and recommended by Du Breuil are very attractive, and admirable methods of training and dwarfing fruit trees, and of crowding a great many into a small space. His method of making an edging to the fruit-border with dwarf apples, inarched together so as to form a connected tree for its whole length, is a capital illustration of the control we may exercise upon vegetation.
Standards and pyramids are often trained as weeping trees, for the sake of gratifying the fancy of the cultivator, and with a view of bringing on that early productiveness which results from the check of the upward current of sap that is incident to such a mode of treatment. This is really a kind of dwarfing so far as it goes, and if commenced early in the life of the tree, it may become very effective, especially when combined with other means ofreducing the growth. These are formed by arching the branches, tying their tips to a ring of wire or hoop secured near the ground, or simply by fastening weights to them sufficient to keep them in the desired position, and by tying the upper limbs to the lower ones. As is well known, the sap flows most readily toward the shoots that occupy a vertical line; it will be seen that its ascent will be seriously retarded in those that are bent, and their vigor will be diminished, and fruit-bearing will be promoted. This process must not be continued too perseveringly, lest the tree become exhausted by over-production.
Du Breuil recommends laying bare the principal roots of the tree in the spring of the year, so as to expose them for the most of their length, and leaving them in this condition during the summer. This exposure of roots to the sun and air diminishes the vigor of the tree, and hence it tends to the production of fruit. He also recommends the removal of a part of the roots in the spring, and replacing the earth; considering this a more energetic operation than the preceding, he advises caution, lest we injure the tree. This is simply root-pruning, a plan that has been pretty thoroughly tested in this country, where, perhaps, its beneficial effects are more needed than in any other, and where we shall even find it advantageous to have recourse to mechanical means for its performance in large orchards by horse-power, as will be set forth in another place.
A very successful method of obtaining the desired effect of dwarfing, which is early and abundant fruiting, consists in transplanting the trees in the autumn; this should be done very carefully, so as to preserve the roots frommutilation as much as possible. The effect of this will be to check the wood-growth the ensuing summer, and fruit-buds will be formed, for it is well known that these two opposite conditions of plant life are complementary the one to the other, and while we always desire to see them both proceeding together in a healthy tree, the wood-growth must have been moderated before we can expect to receive any fruit.
The French and English excel us in training upon walls and espaliers, and we may willingly yield them the palm; since, in this country, it is rarely necessary to incur so great expense for the production of good fruits, and as a means of dwarfing our trees, it is more expensive and requires more skill, care, and watchfulness, than other methods of producing this effect. Espalier training, however, affords the most beautiful opportunity for the illustration of many of the important principles of vegetable physiology, but it should never be undertaken by any one who is not familiar with these, and at the same time willing to exercise great patience and perseverance in their application to the subjects under his control. No blind pursuance of the abstract rules of the art can enable the mere routine gardener to become a successful grower of espalier trees. The modes of training are various, to suit the whims and necessities of the artist. Trees are fastened directly to the walls, or to trellises of wood or of iron, that are placed at a little distance from the masonry, or they may be entirely independent of any such structures, and exposed to the air and light freely on both sides. The trellises may be either vertical, or inclined. The limbs may be made to issue nearly opposite to oneanother, and be trained horizontally in two directions, with successive stages to the top of the wall or trellis, or they may be trained in a fan shape, with various modifications of what M. Du Breuil calls thepalmetteform. And a simple modification of this method of dwarfing may be made with some varieties of fruit, by training a single stem horizontally within a foot of the ground, as a border or edging between the path-ways and the cultivated ground.
The favorite method of training in France, at the present day, appears to be that called thecordon. This may be either the vertical or inclined. In this kind of espalier, the trees are dwarfed by crowding them closely together, and by successive pinching and other mutilation, such as bending and even breaking the shoots, which results in early productiveness. The trees are planted sixteen inches apart, and are trained to single stems, and so treated as to be furnished with the requisite number of fruit-spurs on their whole extent. This is quite a new application of principles, and one which is rudely imitated by Mr. Field's pear hedges, which, however, bear but little resemblance to the elegant cordons of Du Breuil beyond that of dwarfing by crowding and pinching. We are told that among the many advantages of this method, are the diminished time required to cover a wall or trellis with fruit, and the greater facility of replacing a dead or defective tree, which, in the usual espalier methods, is a very serious matter, requiring several years for its restoration and the production of a crop.
We are so blessed, in most parts of this country, with soil and climate that are well adapted to the productionof fruit in the open field, upon sturdy orchard trees, that there is less necessity for introducing these elegant methods of pursuing the fine art of horticulture; and yet there are reasons in the uncertain climate of our winters, why these plans of training and dwarfing should be pursued by those who have the talent and the means for doing it. Until within a few years, there were not many dwarfed pear or apple trees in this country, and they were confined chiefly to French gardens and to the establishments of the wealthy. But since their more general introduction, immense numbers have been propagated and planted, and extensive orchards, particularly of dwarfed pears, have been set out with a view to profit. Some of these have been eminently successful, others are failures; the results will very much depend upon the amount of care which may be bestowed upon them.
The French have long practiced the dwarfing of certain varieties of fruits, and have been very successful in their results; but that wonderful people, the Chinese, excel all others in this branch of horticulture, for which they display a remarkable talent.
Dwarfing by Uncongenial Stocks.—The usual mode, which is literally a partial starvation of the tree by limiting the supplies of crude sap, consists in the use of uncongenial and dwarf-growing stocks, upon which the desired varieties are budded or grafted. These are, for the dwarfed pear, either Quinces, Thorns, the Mountain Ash, or the Amelanchiers; for the apple, the Paradise and the Doucin varieties of apple stocks; for the peach and plum, the Chickasas, or other dwarf plum stock may be used. The free-growing cherries are worked on theMahaleb or the Morello varieties; but it must be confessed, that some of these do not produce a perfect dwarf without other treatment.
To produce a dwarf by grafting on an uncongenial stock, this should be so uncongenial as to form an imperfect union, which checks the downward circulation; the sap that has been elaborated by the organs of the scion is thus kept above the junction of the two woods, and, being so checked, the result is the early formation of fruit-buds, and a premature fruitage of the trees results in a direct proportion to the incompleteness of the union of scion and stock. This is often so very imperfect as to be very easily ruptured, the grafts are often broken out by a very small force being applied to them, sometimes even the weight of the fruit is sufficient to effect a separation, and an examination of the rupture will show how very slight or imperfect the union between the parts has been; in other cases, however, it is difficult to trace the fibres of wood-growth that belong respectively to the stock and to the scion, even when these have been so different as pear and quince, or plum and peach.
It is also considered desirable that the roots of the stock should be small and fibrous, and not long, naked, and straggling; the former will furnish the crude sap in more limited amounts, and are less likely to produce an excessively rampant or luxurious growth in the scion.
Many persons have been disappointed in the Mahaleb cherry, which has been reputed to be a dwarfing stock. It is found, that without the application of other means, the so-called dwarfed cherries grow as freely, at least in their early years, as those worked on the free stock, knownas the Mazzard cherry. They will never make such large trees, however, and those who would enjoy dwarf cherry trees, should combine the different methods of producing the result.
By Pinching.—There are other means of producing the desired effects of dwarfing and early fruiting, which should be mentioned. These consist in systematic efforts to curtail the development of the wood-growth, by judicious pinching, of the tips or points of the branches, and to prevent the rambling of the roots by root-pruning. These it is designed now to examine. Pinching is practiced in the green-house with the happiest effects, and it results in the production of the most perfect form of the plants, and most abundant display of flowers. The constant check which is thus given to the wood system, causes the sap to seek new outlets, and instead of the one limb into which it had been flowing, and causing it to be developed; its flow is now directed to the other buds along its course, which presently burst out into lateral growths, none of which are so strong as the first, and these are induced to change the character of the buds so as to result in the production of flowers and fruit.
This system applied to fruit-trees has been most thoroughly carried out by the French, and is admirably described and illustrated by Du Breuil, in a work calledScientific Culture of Fruit Trees, and reproduced in our own language by Wm. Wardle, an English gardener and orchardist of high reputation.
It is not to be expected that in this country, where fruits are so easily produced, we shall soon reach such a point of horticultural practice as to lead us to the adoption ofthe European system of walls and espalier training, but we shall do well to watch the application of the very important principles involved in their practice, since these may be applied to our orchards with manifest advantage. In reference to the form and management of trained trees, it is established as an axiom that their permanency is dependent upon an equal diffusion of the sap being kept up throughout the whole extent of their branches. This occurs naturally in all trees, because they develop themselves in the forms natural to them, but in our gardens and orchards we make our trees assume unnatural forms. The sap flows to the highest parts by a law which is well known, though not so well understood; as a consequence, the lower branches do not receive their needed supplies, and being smothered by those above them, they eventually die and decay, leaving a naked stem supporting a top, or the common form of the natural tree. To maintain the shape we desire—be this the pyramid, the vase, or the espalier of whatever kind—certain operations must be performed from time to time, as the conditions of the tree may indicate.
Among these, Du Breuil advises to prune the strong branches short and allow the weaker ones to grow long, and thus to restore the balance. This may be done at the spring pruning, and also at any time during the growing season, when it may be necessary to check excessive growth at any one point: and upon this principle depends some of the most important practice of the summer pruning of our vineyards. The sap flows towards the leaves, and by removing them from one part, and leaving a preponderance upon another, we change the direction of itsflow. As the strongest flow is toward those parts that are in a vertical direction, we may also check this tendency, or encourage it, by altering the position of the branch, as is done in the vineyard by tying up the canes we wish to have developed, and depressing the laterals with their fruit; so in a tree, we may depress the shoots which are too strong, and elevate those that are weak, to produce the desired effect. We may also greatly diminish the flow of sap to a strong branch by removing early all its useless buds; this is a sort of premature pinching to be sure, but when we consider the powerful influence exerted by these organs as centers of vitality, we can realize their attractive force in drawing the sap towards them. After the production of the full number of shoots upon the weaker branch, if the foliage continue to predominate upon the stronger shoot, it may be partially removed by early pinching, or cutting through the petioles, not by tearing them off; and as late as possible, remove the surplus and useless shoots from the weaker branches, which were at first needed to encourage the flow of sap in that direction.
The true pinching of the young laterals, or new shoots, should also be done as early as possible to keep them in check on the strong branches, while the same operation may be delayed on the weaker, from which we should remove only those that will be supernumeraries. M. Du Breuil also recommends the stimulation of the weaker limbs, by bathing all the green portions with a solution of sulphate of iron, made by dissolving twenty-four grains in a pint of water. This should be applied in the evening, when it is absorbed by the leaves, and acts as a powerful stimulant.
It is a well established principle, that the chief growth by extension will be made by the terminal bud, and this should either be removed by cutting back, or left upon the limb, according as we desire to grow our wood; if extension of the shoot be our leading object, all the lateral buds must be subordinated. So also, it is well known, that all circumstances, which retard the circulation, are followed by a diminution of the wood-growth, and by the development of flower buds.
The culture of the strawberry affords one of the best illustrations of the benefits and effects of pinching. The runners of this plant may be viewed in the light of wood-growth, or the increase of the plant by extension; even though these slender threads are not permanent, and they only serve to convey a bud to a distance from the parent plant, and place it under favorable circumstances for the formation of a natural layer. They are but annual productions, and hence there is no considerable deposit of woody matter, as in the limbs of trees, but they are thrown out from the parent plant just like woody branches, and are so much substance withdrawn from it, which, if retained or thrown back upon the plant, would have resulted in an enlargement of the main stem of the strawberry plant, and in the development of buds upon the crown, which become stored with the proper juices that result in the production of more abundant blossom buds. The result, however, is so admirable an illustration of this important element in the management of permanent and woody fruit-trees, that we may well look at an herbaceous plant, be it even so humble an individual as the prostrate earth-berry, as our ancestors called the deliciousFragaria.
Apples are generally dwarfed by working them upon the French Paradise stock, which is a very diminutive tree or bush, seldom rising more than a few feet high. This is the true stock for those who wish to indulge in the luxury of dwarf apple trees. Such are very appropriate for the small garden, or for the specimen grounds of a nursery establishment, and they sometimes make beautiful objects in the lawn or among the shrubbery, but they are wholly unsuited for orchard planting, as many a poor deluded purchaser has found out to his sorrow, a few years after having been beguiled by the smooth-spoken tree peddlers, who have sold many thousands through the country to farmers to plant as orchard trees.
There is a more vigorous stock which has been used for the same purpose, but it possesses much less dwarfing power. It is called the Doucin, or English dwarfing stock. This, however, exerts so little of the dwarfing influence, that at the end of eight or ten years the trees are generally about as large as those worked upon free stocks; but it happens unfortunately that early fruitage, the great object of dwarfing, is not attained by their use, for they will not have produced any more fruit than the common trees similarly treated.
By Root Pruning.—Among the many valuable hints which horticulturists have received, with the beautiful flowering and other plants, from our antipodes in the "Flowery Land," none has been of greater value than the practice of root-pruning. In this art of dwarfing even the large forest trees by mutilations of the roots and by other means, this curious people excel all others, as hasfrequently been stated. In Europe, and in this country also, root-pruning has been extensively practiced with the effect of partially dwarfing the trees, but more especially with the object of inducing prematurely the fruitfulness we so much desire, and which is a natural result of the diminished supplies of crude sap furnished by the contracted roots of a tree that has been treated in this manner. The balance between the wood-growth by extension, and that which results in fruitful spurs is sooner established, and the sap is directed to the formation and support of the fruit.
We should not commence the application of this severe treatment until our trees have been allowed to establish themselves firmly in their stations, unless we desire at the same time to produce decided dwarfs by means of root-pruning. In this case the treatment may be commenced in the nursery itself; the stocks should be transplanted once or oftener before being worked, and the young trees should be moved annually, which will so shorten the roots as to make them a mass of fibres, occupying the whole soil close about their main divisions, and the subsequent removals can then be easily effected, with but a slight check to the tree, which becomes furnished with fruit spurs at a very early period of its existence, instead of its requiring years to reach its natural period of fruitfulness, as is the case with some varieties, particularly of the pear.
As generally practiced, however, root-pruning is postponed until the trees have made a free and vigorous growth, and have become well established in their stations. Then if the growth be too vigorous, and there do not appear any indications of the formation of fruit spurs, as is often the case in the fertile soils of the West, ourimpatient orchardists complain of the barrenness of their trees, and seek a remedy in root-pruning. This is generally performed with a sharp spade, with which a trench is dug in a circle around the tree. The excavation should be deep enough to reach all of the lateral roots; these are generally within a foot of the surface. The ditch need not be much wider than the spade, and the soil can be thrown back at once, but all the roots should be severed, if we desire to produce the effect of checking the wood-growth. The diameter of this circle will depend upon the size and vigor of the tree to be operated upon. As a general rule, it may be made in the proportion of one foot to each inch of the tree's diameter. The work may be done at any time after the spring growth has begun to harden, or during the autumn and winter, and until the buds are about to break in the spring. The operation is wonderfully conducive to the end we have in view, and we often see a vigorously growing but barren subject, transformed in a single season into a fruitful tree, covered with blossom-bearing spurs that are full of promise of delicious fruits. In some varieties, however, these fruit spurs require more than a single season for their perfection.
Now it may be objected that this labor will be expensive, and so it is, as all hard work with the spade must be; but what of that, when we consider the happy results that ensue in golden harvests. But it has been suggested that this labor may be performed by farm machinery, using a strong plow, or rather a sharp cutter attached to a plow beam, and drawn by a powerful team at the requisite distance on either side of the rows of trees, and in directions crossing each other at right angles. This, of course, likeall mere mechanical applications, must be uniform, whether the necessities of the trees be equal or not; whereas, by hand-labor, we may vary the distance at which the roots are to be cut, according to the vigor and size of the trees demanding the treatment.
This topic will be again referred to in the chapter on Pruning, where also it will be necessary to recur to the subject of Training, which was incidentally alluded to in connection with Dwarfing.
DIFFICULTIES IN THE OUTSET—WHAT CONSTITUTES DISEASED ACTION—NO ANALOGY TO ANIMAL SICKNESSES—CONGENITAL DEFECTS—DEBILITY. DEFICIENT STRENGTH OF FIBRES—DEFECTIVE FOLIAGE—IMPERFECT AND REDUNDANT BLOSSOMS—THE CIVILIZED AND CULTIVATED PLANT MAY BE ABNORMAL ALTOGETHER—UNSATISFACTORY ACCOUNTS OF DISEASES IN PLANTS—LANKESTER'S CLASSIFICATION CONSIDERED—EFFECTS OF THE EXCESS OR PAUCITY OF MOISTURE, HEAT, AND LIGHT—MODE OF ACTION OF FROST—INJURY RATHER REFERRIBLE TO THE CONDITION OF THE CIRCULATION THAN TO THE DEGREE OF COLD IN MANY HARDY PLANTS—INFLUENCE OF THE SOIL—LIGHT THE GREAT STIMULUS, ITS WITHDRAWAL SUSPENDS HEALTHY ACTION—ITS SUDDEN RESTORATION CAUSES DEATH BY SUN SCALD—INJURY BY SUNSHINE IN WINTER—POISONOUS GASES—MIASMATA—POISONS IN THE SOIL—PARASITIC PLANTS, EPIPHITES, FUNGI, PEAR BLIGHT—VARIOUS THEORIES—WHAT WE KNOW, AND WHAT WE DON'T KNOW—TREATMENT—ROOT PRUNING SUGGESTED—SATISFACTORY RESULTS—MILDEW BLIGHT IN PEACH AND APPLE—TWIG BLIGHT IN APPLE AND QUINCE—THE APPLE BLIGHT—BITTER ROT—CRACKED FRUIT—SCAB—MILDEWS—KIRTLAND'S VIEWS AND SUGGESTED REMEDY—WOUNDS AND INSECTS—NEEDING THE AID OF SURGERY RATHER THAN MEDICINE—DESTRUCTION OF FOLIAGE BY INSECTS IMPAIRS THE HEALTHY CONDITION OF THE PLANT—RESUME—SELECT HEALTHY TREES OF HEALTHY VARIETIES—EMPIRICAL CHARACTER OF TREATMENT USUALLY RECOMMENDED FOR DISEASED TREES—THE BLACK KNOT—THE ROT AND MILDEW OF THE GRAPE.
DIFFICULTIES IN THE OUTSET—WHAT CONSTITUTES DISEASED ACTION—NO ANALOGY TO ANIMAL SICKNESSES—CONGENITAL DEFECTS—DEBILITY. DEFICIENT STRENGTH OF FIBRES—DEFECTIVE FOLIAGE—IMPERFECT AND REDUNDANT BLOSSOMS—THE CIVILIZED AND CULTIVATED PLANT MAY BE ABNORMAL ALTOGETHER—UNSATISFACTORY ACCOUNTS OF DISEASES IN PLANTS—LANKESTER'S CLASSIFICATION CONSIDERED—EFFECTS OF THE EXCESS OR PAUCITY OF MOISTURE, HEAT, AND LIGHT—MODE OF ACTION OF FROST—INJURY RATHER REFERRIBLE TO THE CONDITION OF THE CIRCULATION THAN TO THE DEGREE OF COLD IN MANY HARDY PLANTS—INFLUENCE OF THE SOIL—LIGHT THE GREAT STIMULUS, ITS WITHDRAWAL SUSPENDS HEALTHY ACTION—ITS SUDDEN RESTORATION CAUSES DEATH BY SUN SCALD—INJURY BY SUNSHINE IN WINTER—POISONOUS GASES—MIASMATA—POISONS IN THE SOIL—PARASITIC PLANTS, EPIPHITES, FUNGI, PEAR BLIGHT—VARIOUS THEORIES—WHAT WE KNOW, AND WHAT WE DON'T KNOW—TREATMENT—ROOT PRUNING SUGGESTED—SATISFACTORY RESULTS—MILDEW BLIGHT IN PEACH AND APPLE—TWIG BLIGHT IN APPLE AND QUINCE—THE APPLE BLIGHT—BITTER ROT—CRACKED FRUIT—SCAB—MILDEWS—KIRTLAND'S VIEWS AND SUGGESTED REMEDY—WOUNDS AND INSECTS—NEEDING THE AID OF SURGERY RATHER THAN MEDICINE—DESTRUCTION OF FOLIAGE BY INSECTS IMPAIRS THE HEALTHY CONDITION OF THE PLANT—RESUME—SELECT HEALTHY TREES OF HEALTHY VARIETIES—EMPIRICAL CHARACTER OF TREATMENT USUALLY RECOMMENDED FOR DISEASED TREES—THE BLACK KNOT—THE ROT AND MILDEW OF THE GRAPE.
In opening a discussion upon the nosology of vegetation, it may be expected that one who had spent many years of his life in the investigation of the diseases of the humanfamily, and at the same time was something of a student of comparative anatomy and physiology, tracing analogies between the animal and vegetable kingdoms, should be familiar also with the diseases of plants. Such an anticipation, it is feared, will not, in the present instance, be realized. Indeed, the writer feels very much at a loss how to proceed in discussing this branch of the subject, and hardly knows what departures from undoubted health and vigor should be considered worthy of the title of disease. Nor is it easy to trace the causes of the conditions that are generally viewed in the light of maladies. We find the manifestations both in the tree or plant, and in its several parts, and also in the products which chiefly interest us; the fruits themselves, are often deteriorated by what is called diseased action of different kinds. The analogy to diseases of animals is certainly not very distinct. We do not find anything like fevers, or gout, or rheumatism, in plants, but we may consider some of their conditions somewhat in the light of dropsies, and plethora or hypertrophy on the one hand, and of anæmia or atrophy upon the other; we may consider canker and the death of some parts of a plant analogous to gangrene, and mortification in the animal subject. Then again we find congenital defects in individuals among plants, just as we do among animals. Some are always less vigorous than others, and thus certain varieties seem possessed of a degree of inherent disease that perpetually prevents them from displaying the requisite strength and vigor which we so much desire in our plantations. Certain varieties that, from the size and excellence of their fruits, have attracted the attention of pomologists, are so deficient in health and vigor as to beconsidered diseased, and are therefore very properly condemned as unworthy a place in our orchards and gardens; others appear simply deficient in the production of some one part, as is illustrated by the inferior strength of the woody fibres of some trees, which break easily under the weight of their own fruit, and thus destroy the symmetry of the tree and diminish its productiveness. Others have defective foliage, which is attended by the imperfect performance of the functions of growth, both in the fruit and in the sustaining woody fibres; others again produce defective blossoms with either a redundancy or deficiency of the parts that are necessary for the production of the seeds needed for the perpetuation of the species. When the parts are deficient, the flowers are called barren or infertile. A redundancy or multiplication of parts is seen in double flowers of our gardens, where they are much prized for their beauty, though considered monstrosities by the botanist, and perhaps properly referred to diseased action by the nosologist.
It is evident, that very often the conditions of a plant and its products, which we most highly prize, and towards which all our efforts in its culture are directed, are really departures from the natural and healthful status; in other words, what we covet, is really a state of diseased and abnormal action. With the other secondary objects of occupying and ornamenting the barren wastes of the earth with plants, and thus supplying food to hosts of insects, and to the higher animals, nature also has primarily in view, the production of perfect seeds for the perpetuation of their species, by the plants that are profusely scattered over the globe. Man, on the contrary, often rejects thetrue seeds as worthless when compared to their juicy fleshy envelopes that constitute his favorite fruits, or the enlarged and succulent roots, tubers, stalks, and leaves, that characterize his garden vegetables and field crops; while in the grains proper he seeks sustenance in the true seeds, which become the object of his greatest care and ingenuity to enlarge, to increase, and to develop, particularly in regard to their nutritive qualities.
Most writers upon the diseases of plants have given us very indistinct notions upon the subject, and have done very little to enlighten their readers; while they have written voluminously upon the unhealthy and unsatisfactory condition of certain vegetables, and have given us most extensive accounts of the treatment by which they propose to remedy the evils complained of, we gather little of the information needed to enable us to understand the true state of the case, or of the causes of the disease, if it is to be considered such. The reader need not expect that he will be more enlightened by this chapter than he has been by the essays to which reference is here made, but he will be led to a consideration of some of the causes of those departures from health and vigor which are considered diseased action, and in this way he may possibly be put upon the track which will lead him to the avoidance of disastrous results. More than this will not be attempted.
Perhaps the most satisfactory account of diseases of plants is that given by Lankester, in which he divides them according to their causes, as follows:
1st—Those produced by changes in the external conditions of life, such as redundancy or deficiency of theingredients of soil, of light, of heat, air, and moisture.
2d—Those produced by poisonous agencies, as by injurious gases, miasmata in the air, or by poisons in the soil.
3d—Those arising from the growth of parasitic plants, such as the various Fungi, Dodder, Mistletoe, etc.
4th—Such as are caused by mechanical injuries or wounds, and by the attacks of insects.
These may be considered separately: 1st—It may be assumed, and has been already well established by botanists, that every plant has its own peculiar constitution, adapting it to certain atmospheric conditions, and that for its healthful and successful culture, these must be understood and adhered to, within comparatively narrow limits. Tropical plants, as is well known, cannot be cultivated beyond their natural limits, except under circumstances where their natural conditions are nearly imitated by the gardener; and even in our stoves and hot-houses, these plants do not compare in vigor with their fellows that luxuriate in the hot and steaming atmosphere of the tropics, under the stronger light of such a clime as is natural to them. On the contrary, the plants of northern latitudes will not grow and produce seeds where temperature is too elevated. Those from a humid atmosphere suffer in an arid clime, and those which thrive in dry sandy regions suffer equally when introduced into a humid atmosphere.
Thus we find, that where there is too much moisture for some of our cultivated plants, they are inclined to be too succulent, and this very excess may produce a dropsical condition that is really a state of disease. Thus we suffer in a loss of fruit, which will fall badly before itsperiod of maturity, and that which remains its full time is found to be thin and watery, deficient in the high spicy aromatic flavor which is so highly appreciated by the connoisseur of these choice products. When, on the other hand, the arid character of the soil and climate prevail to an extent that is uncongenial to any particular fruit, we shall find that its growth is arrested, and that its highest qualities are not adequately developed: this is frequently observed in an unusually dry season—and in California, where irrigation is required to enable the orchardist to produce some of the succulent fruits, the most remarkable size and beauty have been attained, but we are told that it was often at the expense of the desired flavor that the same varieties acquire, under circumstances more advantageous to the development of their superior qualities.
So in many of our fruits, the successful results depend upon the hygrometric condition of the atmosphere, and Liebig suggests that a very prolific source of diseased action in plants, arises from the suppressed evaporation and transpiration consequent upon such atmospheric conditions.
Too much moisture prevailing at the time of the blossoming of our fruits, especially moisture precipitated in the form of rain during this period, is sometimes disastrous to our crops, both of cereals and of orchard fruits. Continuous showers prevent the development of the pollen-grains, and their transfer to the stigmas of the blossoms, so that the fruit does not set well. Fortunately this does not often occur in our glorious climate, which is so highly favored by an abundance of light and sunshine, which are the great and essential stimuli of the higher orders ofplants. The loss of our fruit crops in some parts of the Ohio Valley in the years 1862, 1865, and 1866, was fairly attributed to this cause.
We must not overlook the unhealthy influences produced by an excess of moisture in the earth. Many plants that naturally delight in a dry porous soil, become weak, unfruitful, or even seriously diseased when they are planted in low wet grounds, or upon such as are underlaid by a very tenacious sub-soil, while an opposite condition is equally unfavorably to those that are naturally more aquatic in their tastes and habits. In the former case we learn to avoid such soils and situations, unless we are able to change their character in this respect by thorough under-draining, which will completely remove the evil, and the remedy becomes merely a question of expense.
A certain amount of temperature may be assumed as requisite to every plant, or rather it may be affirmed that some plants cannot exist and thrive except within a certain range, and it has been asserted that each class of plants requires a mean temperature for the year that shall not vary many degrees: the range of this variation has perhaps never been satisfactorily ascertained. But it is well known, that both heat and frost act injuriously upon vegetation. Mr. Lindley tells us that "the extreme limits of temperature which vegetables are capable of bearing, without destruction of their vitality, have not been determined with precision." When the temperature is maintained at a higher point than is natural, the plant is excited to undue activity of growth; but this is attended with an enfeebled condition, often seen in badly managed green-houses. Mr. Knight found that certain plants wererendered abortive by the production of male flowers only, when exposed to too great heat, and by an opposite treatment, when subjected to a low temperature for a long time, others produced only female flowers. In some plants a high degree of heat, with moisture, results in the production of leaves only, and Humboldt found that wheat was grown about Xalapa, Mexico, as a fodder plant, because it produced an abundance of grass, but did not form ears nor grain.
A diminished temperature, on the contrary, removes the stimulus of growth, and leads to the suspension of all vital action in proportion to its reduction. At the freezing point it is probable that all such action ceases, though in this regard there is great difference among plants; the mosses and lichens will flourish, and the Chickweed will vegetate and blossom at a temperature very little above freezing. The access of frost, after vegetation has somewhat advanced, often proves very disastrous, and we not unfrequently lose our crops of fruit by such an occurrence during the period of blossoming, or even afterward.
Some plants in a dormant condition, will endure uninjured a great depression of temperature, while others will be destroyed by the slightest approach of frost. According to De Candolle, this may depend upon the greater or less amount of water they contain, upon the greater or less viscidity of their fluids, or the rapidity with which these fluids circulate. Those with larger cells he thinks most easily injured by frost, and those which contain a great deal of air are able to resist it best. The freezing point will vary according to the quality of the sap, for we know that different vegetable juices congeal at differenttemperatures. The manner in which cold acts upon plants depends upon their physical structure. Lindley says, freezing is attended with the following effects:—The fluids contained within the cells of tissue are congealed and expanded—this produces a laceration of the cell-walls, and impairs excitability by the unnatural extension to which the cells are subjected; the air is expelled from the air-vessels and introduced into parts naturally intended to contain only fluid; the green coloring matter and other secretions are decomposed, and the vital fluid or latex is destroyed, and the action of its vessels is paralyzed. The interior of the tubes, in which fluid is conveyed, is obstructed by a thickening of their sides. So we have as a result, both mechanical, chemical, and vital changes.[16]
Our hardy fruit trees are woody perennials that hybernate during the winter. Yet we find that even these suffer upon some occasions from a great depression of temperature; it has been asserted that a certain degree of cold would inevitably destroy the blossom buds at least, and we often find that the bark is burst off from the wood, and in some instances the wood itself is so injured as to suffer from a kind of decomposition, and to become affected with a change generally known as the dry rot, losing its elasticity and hardness, and acquiring a whitish color, which is supposed may arise from the introduction of the mycelia of fungous growths. Now it is believed that these injuries do not arise so directly from the degree of cold to which the tree has been exposed, as to the condition of its circulation at the time of the exposure. If thesap have been excited by mild or warm weather, as is so apt to be the case in our changeable climate, the sudden depression of temperature will produce disastrous effects, even when the cold has not been very severe. This is manifested by the bursting of the bark in young trees in the early part of winter, while they are yet holding their leaves, and of course having a circulation somewhat active. Hence the importance, now very well understood by our nurserymen, of checking the growth of young trees in time to have their terminal buds thoroughly ripened before the approach of frost. This, to a certain extent, is subject to our control; but we cannot foresee the character of the seasons upon which the safety of our orchard trees will, in a great measure, depend, and they are less easily managed. When the autumn is dry, and continued late into winter, as sometimes happens, we see a perfect ripening of the wood, with a great development of blossom buds, and then we may confidently calculate upon the safety of our fruits, provided they be not exposed to a warm period at mid-winter, that shall excite some activity in their circulation, which would suffer terribly from any sudden and great depression of temperature such as frequently occurs, carrying the mercury from summer heat to a point below zero, in a few hours. Such a change has amounted to 68 degrees in nine hours.[17]
The influence exerted by the soil upon the healthiness or unhealthiness of our trees has already been alluded to incidentally, but it is an important subject of inquiry whether this may arise from a redundancy or a paucity of some particular ingredients necessary to sustain the plantswe desire to cultivate. Liebig has pointed out how chemistry may be brought to our assistance in solving such a question. As all the inorganic elements found in a tree and its fruits, must have been derived from the soil in which it grew, he suggested that the ashes of the plant would show us exactly what it needed, and then an examination of the soils would inform us whether they contained all the necessary elements, and in the right proportion. Hence arose the doctrine and the practice of applying special manures, which has been so fashionable in our day. Though there be many doubters as to the efficacy of such investigations and practices, most sensible and enlightened agriculturists admit the truths which Liebig has propounded.
Light is the great stimulus of vegetation, an essential element to its existence: its withdrawal is followed by an arrest of some of the most important functions of vitality, and yet we find that there is a great difference among different species, as to their requirements of this element, and also that various parts and several products of vegetation require very different degrees of light for their perfection. It is also found that a sudden exposure of parts from which it had been withheld, is often attended with disastrous consequences. Its withdrawal does not so immediately destroy the plant, being attended with the etiolation of the parts that are usually colored, but a sudden re-exposure to the sun's rays will now destroy the plant. So the removal of a portion of the foliage from a tree, or the exposure of the bare stem of one that had been previously sheltered, is often attended with severe effects, known as sun-scald—for which there is no remedy, but very easymodes of prevention. The best of these is to provide against the evil by reserving the lower branches to shade the stem. There are other excellent reasons for this practice, which will be brought forward in the chapter on Pruning.
Frequently, however, the nurseryman, or perhaps the injudicious efforts of the planter himself, may have removed all the side branches of the young tree, and as these cannot be replaced, we may substitute for them a shelter from the scorching sun to which the newly planted tree is exposed. This may be done by tacking two narrow boards together at their edges, like a gutter spout, and setting them upright on the south side of the tree to shade it. A wisp of straw, tied loosely to the stem, will answer a very good purpose; but both of these appliances are objectionable, because they furnish a shelter for insects, and thus they fall short of the natural shading of the stem by the foliage of its own branches.
It is not only the scorching suns of summer that damage our young trees that are thus exposed by injudicious trimming. Even the bright rays of a mid-winter sun, falling upon the frozen stem, will often effect the most serious damage, and should be guarded against with equal care; but here the natural protection will answer, for the shade of the naked spray of the laterals is found all-sufficient in the well-trained tree.
2d—To resume the consideration of Lankester's causes of disease, it must be admitted that some diseased conditions may be produced by poisonous gases, but the usual result will be the death of plants confined in such an atmosphere. The natural power of diffusion of all gasesamong one another in the open air, prevents the danger that would ensue in a confined situation. The accidental production of sulphurous and other poisonous gas, or the escape of smoke from the flues or from the tobacco-pan in the green-house, sometimes produces the most disastrous effects upon the plants subjected to their action. So, in crowded cities, it often happens that the effects of coal smoke and other gases, generated in the furnaces and manufactories, are very injurious to vegetation. The coal soot falls in flakes like lamp-black, which covers the surface and obstructs the transpiration of the stomata, and thus seriously affects the health of plants in such situations.