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 on 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.