In the first volume of the transactions of the London Horticultural Society, Mr Knight has made some ingeni ous and excellent remarks on the training and pruning of fruit-trees. His year•old plants are headed down, as usual, early in the spring, and two shoots only are trained from each stem, in opposite directions, and in an elevation of about 5°. (Plate CCCIX. Fig. 6 ) To procure the shoots to be of equal lengths, the stronger is depressed, or the weaker elevated. All lateral shoots are destroyed. Thus far it may be remarked, Mr Knight's method agrees very much with Hitt's, described in his Treatise on Fruit-t•ees. This shape, Mr Knight observes, ought to be given to young trees in the nursery, and is perhaps the only one that can be given to them without the risk of subsequent injury. Next season, as many branches are suffered to spring from each plant as can be conveniently trained, without shading each other ; and by selecting the strongest and earliest buds towards the points of the year-old branches,. to be trained lowest, and the weakest and latest near their bases, to be trained inclining upwards, each an nual shoot will be nearly equal in vigour. (Fig. 7.) In the following winter, the shoots are alternately shortened, and left at full length. In the course of the third year, (Fig. 8.) if the tree be a peach, the central part consists of bearing wood : And, upon the whole, the size and ge neral health of the trees trained in this way, afford evidence of a more regular distribution of the sap than Mr Knight has witnessed in any other mode.
The distance at which the branches are laid in, in all the different modes, varies from eight to ten inches, accord ing to the nature of the tree, or the size of its foliage or fruit. While fan-trained trees are still in progress, a few more shoots are preserved at the summer pruning, than are likely to be ultimately laid in : this is for fear of acci dents. Trees that have filled the spaces allotted to them, are disbudded of most of the woodbuds that appear. Wood buds on old spurs are always displaced. Trees which are in training for the horizontal method require different management. The leading stem is constantly to be attend ed to; all the buds that appear on it are carefully preserv ed, till enough be procured to lay right and left, and form the tree. All wood-buds on the horizontal branches, ex cepting the leading one, are displaced. The fan-training is considered as best for apricots, cherries, and plums, placed against walls, even though the walls be low. None of these kinds of fruit answer well for espaliers; cherries or plums succeed better as half standards or dwarf stand ards.
81. The wall-trees which have now been spoken of are called dwarfs by the gardeners. It is a very common practice to train high standards on the intermediate spaces between the dwarf trees; such trees are in Scotland term ed riders,(§ 63.) Plants four or five years old are preferred, because they are but temporary, and the object is to get fruit as soon as possible. Some good judges have con demned this plan of temporary trees as hurtful ; being calculated to deprive the permanent trees of a proportion of the nourishment which they would otherwise draw from the border: but if the border be tolerably rich, and be only slightly cropped with herbaceous plants, it does not seem likely that the temporary trees can do much in jury.
82. In popular language, the term Esfialier is some what equivocal : it means either rows of fruit-trees planted like hedges, or the individual trees composing the rows ; or, lastly, it means the stakes or rails to which the branch es of the trees are tied. By using the terms espalier-tree and espalier-rail, ambiguity may always he avoided. Of late years, some have proposed to banish espalier-trees alto gether, alleging that they injure the kitchen-garden quar ters, by depriving them of sun and air. But in point of fact, they exist in the greater number of kitchen-gardens, and are not likely soon to be laid aside. If they are some times injurious by depriving the plants of air, they are at other times very useful, acting as a hedge in protecting the young crops from the violence of strong winds. Espa her trees generally produce excellent fruit, the sun and air having access to both sides of the tree ; they commonly afford abundant crops, and the fruit is not apt to be shaken by high winds. Further, they tend to hide the crops of culinary vegetables from the eye, and to render the walk of the kitchen garden as pleasant as an avenue in the shrubbery.
Apples and pears are the fruits best suited for espaliers. The apples are generally grafted on crab stocks, to keep them of moderate size ; or, if the tree be wished still smaller, on Dutch paradise stocks. The distance allowed between the former is from 30 to 40 feet ; between the lat ter, 25 is found sufficient. These may seem large spaces at first; and, to take away the naked appearance, a small cherry-tree, or white currant bush, is sometimes planted in each interval. It is to be studied that, in the same line of rail, trees of similar growth be planted, so that the whole may be nearly equally filled. The trees, when planted, should he of one year's growth, or at most of two years. If the rail be not previously erected, so that the branches can be tied to it, a stake is necessary, to pre vent wind-waving. Very often, the permanent rails arc not put up till the trees have been two or three years train ed on temporary stakes. Simple ash-poles firmly stuck in the ground; and either charred or smeared with tar at the bottom, to retard rotting, form a very efficient substitute for a rail ; for it is to be observed, that during summer, when the leaves are expanded, they equally hide the rough est poles, or the most finished rail. Mr Nicol, however, recommends sinking hewn stones in the earth, and fixing a wooden rail in them : and a writer, in the Scottish Hor ticultural Memoirs, vol. i. has described a kind of cast iron espalier-rail, which of course must be highly dura ble, and, what is remarkable, is cheaper at the first than a wooden one. Some gardeners shorten the head of the tree in the usual way ; others preserve the original branches at full length, never cutting a branch unless where there is a real deficiency of wood for filling the rail. The pruning is chiefly done by disbudding in the summer season. The distance at which the branches are laid in depends on the size of the fruit and leaves; when these are large, seven or eight inches are required ; when small, four or five may be sufficient.