Root pruning is a method of trenching around the tree to cut away the tap roots. This has the same effect as “ ringing” in helping a tree to become more fruitful. It needs to be done carefully. I once carried out the operation on a pear tree grown against a wall wlaidh, ‘owing to an exceptionally dry summer, caused the loss of the tree.
We root prune the tree, of course, when it is transplanted, because no matter how carefully this operation is done considerable quantities of roots are removed when a tree or shrub is lifted. In nurseries, trees are lifted every year so that they are in a fit condition to be moved when ordered by clients without undue loss of root system.
When root pruning to induce a tree to become more fruitful, I would recommend that it be done in halves. Try cutting a semicircular trench, say 3 ft. away from the tree. Work under the tree root and cut away any tap roots met below say 18 in. or 2 ft. of soil. This will have some effect in restricting the growth of the tree, and if you notice that it increases the fruitfulness but does not quite retard the growth sufficiently, you can then, after two years, root prune the other half. The operation is best carried out during the winter, when the tree is dormant. Trees, such as cherries, plums, pears and apples, may be treated in this way.
The only roots that need to be cut away during root pruning are the thick anchorage roots and not the fibrous roots. An important precaution after root pruning is to stake the tree securely to prevent it being blown down during a gale.
Sometimes a fruit tree—pear or apple —will produce an abundance of wood and leaves without bearing fruit.
The theory of ringing is that by cutting the bark the flow of sap from the leaves down to the roots is partly prevented. This restricts root development, thus preventing excessive growth of branches and foliage.
METHOD OF RINGING
The method is as follows: With a sharp knife remove the two half-rings of bark in. wide and about 2 in. to 4 in. apart and on opposite sides of the stem. The cuts end so that a line drawn vertically up the trunk would touch the ends of the two half-rings. The best time is when the trees are in bloom. After making the cuts, pull out the bark down to the white wood and paint over the cut portion with white lead paint.
Ringing prevents the dropping of unripened apples, and cases are known where pears which have flowered without fruiting have been brought into bearing.
Summer pruning is seldom performed on large standard trees, but for apples and pears grown as cordons or espaliers it is most efficacious in controlling leaf, growth.
On young and vigorous trees the tips of the side shoots can be nipped out while still soft in May or June;. leaders should never be shortened. Older trees growing more slowly should be left till August, when the shoots are cut back with secateurs to five or six fully-developed leaves.
Shoots must never be cut- back very severely as this would cause the dormant buds to grow and form additional shoots. Very vigorous shoots can be broken through half way and left to hang on the tree. This is unsightly, but by continuing to grow they still use sap. And prevent the lower buds from developing.
All these methods conserve the strength and encourage the production of fruit buds. In addition, the removal of some leaves allows more sunlight to reach the fruit and give it colour and flavour.
PRUNING FRUIT TREES
First decide which are the leaders, that is, the shoots that are to form the main branches, then prune all other shoots for spurs. These should be cut back from five to seven buds according to strength—the weaker the shoot the harder it should be cut—and the leaders can then be attended to.
The most important stage in the pruning of fruit trees is during the first three or four years. It is then that the framework of the tree is formed. Bush, half-standard and standard trees should all have branches radiating from the trunk more or less at the same point to form an open bowl-shaped head.
For the first three or four years after the tree is planted the leaders are cut back by a half and afterwards annually by a third of their total length. The pruning in earlier years is to encourage the production of a few really strong main shoots on each branch. Later work consists of shortening spur shoots, with leaders treated as before.
Branches of fruit trees, especially standard or half-standard trees should not be allowed to ‘carry an excessive quantity. During June a certain amount falls naturally, but after this “ June drop” hand thinning will probably be necessary. No diseased, misplaced or
touching fruit should remain on the tree. In the case of apples and pears, they should be thinned to approximately 6 in. apart: this varies with the size of the variety. By doing this each fruit will grow to a better size and shape and will colour evenly and be of good flavour. Remove leaves that shadow the fruit.
Beginners often think that the more manure they can give their fruit trees the heavier will be the crop. This is not so. A tree which is growing very rapidly and producing long shoots does not make fruit buds in such quantities as one making less leaf growth.
Various methods can be adopted to counteract this production of too much wood and several of them will be decribed in detail. Before starting any of these laborious methods be Certain that the trouble is not due solely to the application of too much fertilizers. Reduce the dressings given for a season and if the tree continues to grow too fast start more drastic treatment.