There are several ways of arranging the trees in an orchard. The principal are as follows: Square, all trees at equal distances in rows at right angles to one another. Quincunx, as the last with one tree in the middle of each square. Triangular, trees at the points of an equal sided triangle, this being repeated right through the plantation. Cordons and trained trees are almost always planted in straight, parallel rows or against walls and fences.
In large orchards it is a frequent practice to plant permanent, slow-maturing varieties at the full distance apart with quick-maturing trees or small fruits (e.g. currants, gooseberries, etc.) in between. These latter are known as fillers and are removed after from ten to fifteen years, by which time the permanent trees are beginning to require all the space. A drawback to mixed plantations is the difficulty of carrying out spraying and feeding programmes suitable to all the trees.
Cultivation of Orchards. Growth is always slower when the ground beneath trees is grassed than when it is cultivated, but trees tend to be more fruitful and bear fruit of better colour and quality when grassed under. In consequence young trees are usually grown on cultivated ground, but this may be grassed down after eight to ten years. Another scheme with much the same object is to keep ground cultivated until fruit is well formed and then allow the growth of summer weeds for a few weeks, digging or ploughing these in later. The weeds must not be allowed to seed.
On no account must deep cultivation be carried out near established fruit trees, or surface roots will be destroyed. Near large fruits, e.g. apples, pears, plums, cherries, etc., it is not safe to dig more than 4 in. deep. For bush fruits, e.g. currants and gooseberries, 2-3 in. should be regarded as the maximum ; strawberries, raspberries, etc., 1-2 in.
Unfruitfulness. This may be due to one or other of several causes. Most fruits are only formed if the flowers are fertilized with pollen. In some varieties, e.g. Apple Bramley’s Seedling, and Pear Pitmaston Duchess, the flowers carry little or no pollen and fertilization can take place only if another variety of the same kind of fruit which bears pollen liberally is grown near by. In other instances, e.g. most sweet cherries and, to a lesser extent, apples, pears, and plums, pollen is borne freely but is partially or wholly ineffective on flowers of its own variety and sometimes also with flowers of certain other varieties. Varieties which will not produce fruit with their own pollen are said to be ‘self sterile’ ; those which will bear some fruit with their own pollen but more when cross-pollinated, are described as ‘partially self fertile,’ while those with pollen which is wholly effective on their own flowers are ‘self-fertile.’ Where the pollen of one variety will not fertilize the flowers of another, ‘incompatibility’ is said to exist between the two.
In planting an orchard it is important that varieties should be assorted in such a manner that the pollen of one fertilizes the flowers of another. Note that flowers can be fertilized only with pollen of the same kind, apples with apples, pears with pears, etc.
Even when the right kind of pollen is available in sufficient quantity it must be carried from flower to flower. This is largely the work of bees and other insects. Lack of these may cause unfruitfulness. This can be overcome by introducing bees or by hand fertilizing the flowers by carrying pollen to them on a camel hairbrush.
Cold, damp weather at blossom time may keep insects away, while frost may kill the blossom outright. This is a particular danger with early flowering fruits such as peaches, nectarines, cherries, and plums. Under nourishment of trees may also prevent effective fertilization. This can be remedied by proper feeding.
Young trees that are growing very freely often fail to produce any blossom at all. Their excessive vigour can be checked by opening a trench round them in October and severing the coarser roots (root pruning), or by removing a ring of bark 1 in. wide from around the main trunk or the base of each main bough in early May (bark ringing). This latter method should not be practised with stone fruits (e.g. plums, cherries, etc.), as it is liable to cause gumming.
Fruits for Special Localities
- DAMP PLACES. Blackcurrants, quinces.
- NORTH AND EAST WALLS. Morello cherries, currants, gooseberries and such plums as Czar, Belgian Purple, Oullin’s Golden Gage, Rivers’ Early Prolific, and Victoria.
- SOUTH AND SOUTH-WEST WALLS. Apricots, peaches, nectarines, figs, grapes, and choice dessert plums, pears, and apples.