Heavy pruning of the top tends to the production of wood; therefore the severe pruning of orchard trees, following three or four years of neglect, sets the trees into heavy wood-bearing, and makes them more vigorous. Such treatment generally tends away from fruit-bearing. This heavy pruning is usually necessary in neglected orchards, however, to bring trees back into shape and to revitalize them; but the best pruning-treatment of an orchard is to prune it a little every year. It should be so pruned that the tops of the trees will be open, that no two limbs will interfere with each other, and so that the fruit itself will not be so abundant as to overload the tree.
In general, it is best to prune orchard trees late in winter or early in spring. It is sometimes better, however, to leave peaches and other tender fruits until after the buds have swollen, or even after the flowers have fallen, in order that one may determine how much they have been injured by the winter. Grape vines should be pruned in winter or not later (in New York) than the first of March. If pruned later than this, they may bleed. The above remarks will apply to other trees as well as to fruits.
If the best size and quality of fruit are desired, care must be taken to see that the plant does not overbear.
Thinning of fruit has four general uses: to cause the remaining fruit to grow larger; to increase the chances of annual crops; to save the vitality of the tree; to enable one to combat insects and diseases by destroying the injured fruit.
The thinning is nearly always performed soon after the fruit is thoroughly set. It is then possible to determine which of the fruits are likely to persist. Peaches are usually thinned when they are the size of one’s thumb. If thinned before this time, they are so small that it is difficult to pick them off; and it is not so easy to see the work of the curculio and thereby to select the injured fruits. Similar remarks apply to other fruits. The general tendency is, even with those who thin their fruits, not to thin enough. It is usually safer to take off what would seem to be too many than not to take off enough. The remaining specimens are better. Varieties that tend to overbear profit very greatly by thinning. This is notably the case with many Japanese plums, which, if not thinned, are very inferior.
Thinning may also be accomplished by pruning. Cutting off the fruit-buds will have the effect of removing the fruit. In the case of tender fruits, as peaches, however, it may not be advisable to thin very heavily by means of pruning, since the fruit may be still further thinned by the remaining days of winter, by late spring frost, or by the leaf-curl or other disease. However, the proper pruning of a peach tree in winter is, in part, a thinning of the fruit. The peach is borne on the wood of the previous season’s growth. The best fruits are to be expected the strongest and heaviest growth. It is the practice of peach-growers to remove all the weak and immature wood from the inside of the tree. This has the effect of thinning out the inferior fruit and allowing the energy of the tree to be expended on the remainder.
Apples are rarely thinned; but, in many cases, thinning can be done with profit.
Washing and scrubbing the trees.
The washing of orchard trees is an old practice. It usually results in making a tree more vigorous. One reason is that it destroys insects and fungi that lodge underneath the bark; but probably the chief reason is that it softens the bark and allows the trunk to expand. It is possible, also, that the potash from the soap or lye eventually passes into the ground and affords some plant-food. Trees are ordinarily washed with soap suds or with a lye solution. The material is usually applied with an old broom or a stiff brush. The scrubbing of the tree is perhaps nearly or quite as beneficial as the application of the wash itself.