This section is from the book "The Gardener V2", by William Thomson. Also available from Amazon: The New Organic Grower: A Master's Manual of Tools and Techniques for the Home and Market Gardener.
What is known by the term disbudding the Peach, consists in the removal of all the buds while in a small state that are not required to grow into shoots, to furnish wood bearing fruit for the following year. This operation should be begun early, as soon as the buds have started. They should not all be removed at once, but at three different intervals of time. At the first disbudding remove those which are termed by gardeners fore-right buds - that is, those that are on the front side of the shoots and that would grow at a right angle from the trellis - and those which are situated on the opposite side of the shoot, thus leaving those that are right and left. In about twelve or fourteen days after this, about the half of those left should be removed at intervals along the shoot, always leaving the best-looking two buds near the base. The trees should be examined, and finally disbudded in about a week after removing all except the most promising bud near the base, which is to form the chief growth for next year's fruiting; on short stubby growths, this bottom bud and the terminal one will be enough to leave. On longer shoots, one or two intermediate ones may be left if there is room enough to tie them in without crowding the tree.
But always give the preference to the lowest-placed buds.
In removing the last of the superfluous buds, when they have got stronger than those taken off at the first and second disbuddings, a thin sharp knife should be used, as it makes a less and cleaner wound than when they are detached by the hand. The leading shoot, if not required to furnish the tree as in the case of young trees, should be stopped when it has grown 1 foot; but allow the lateral growths for next year's fruiting to grow their full length, and keep them regularly tied to the trellis as they grow - using for this purpose soft matting, taking care not to tie too tightly, but leaving room sufficient for the wood to swell.
The common error of tying in too many young growths should be avoided, as one of the greatest errors in Peach culture. It crowds the tree with wood that is not required, and prevents the sun and air from acting properly on the foliage, and the result is weak, unripened, and unfruitful wood. Whenever any given growth shows that it is going to be much stronger than the rest, it should either be cut out altogether, or stopped, and restopped if necessary, to prevent its monopolising the sap that should go to the other parts of the tree.
After the fruit are all gathered, look carefully over the trees and untie and cut out at once those shoots from which the fruit have been gathered and which are not necessary for another year. This gives more room to the young wood required for the ensuing crop, and concentrates the energies of the tree on their maturation. It is not easy nor necessary thus to cut out all the wood that requires to be removed, but the lessening of it leaves but little to do at the winter or early spring pruning, as the case may be, and it lets more air and light at the foliage and buds of the shoots that are left, and necessary to furnish the next crop.
All Peach-trees that are vigorous, and the wood of which has been well ripened, generally set a great many more fruit than are needed, and therefore they require to be thinned off. This operation should not be completed all at once, but gradually, and not finally till the fruit are stoned. As soon as the fruit have swollen sufficiently to burst and throw off their flowers, the first thinning should take place. Where the fruit have set in clusters of twos and threes, remove all but the best-formed and largest fruit, those that are placed on the under sides of the shoots and those that are very near to the wires, and that would not get room to swell if left. When the fruit have attained the size of marbles, a second thinning should take place, removing all the smallest fruit and those that are nearest the top and the bottom parts of the bearing shoot - leaving the largest about the middle of them. Although I have never experienced very much dropping of the fruit in the process of stoning, it is always best to leave considerably more at the second thinning to be removed after they have completed the formation of the stones; then the final thinning should take place.
The weight of crop must be regulated by several considerations: if the trees are young, and show a tendency to make too strong a growth, then it is best to crop rather heavily, say a fruit to every 6 or 7 square inches of surface. The ratio of cropping should be graduated according to the vigour of the trees. Those which have covered a considerable allotted space, and that are in what may be termed good bearing condition, should not be taxed so heavily. If fine fruit are required, a fruit to every 10 or 12 square inches is sufficient. Of course their distribution may be unequal, and it is desirable that on the lower branches - stretching more at a right angle with the stem - the fruit should not be so thick as on the central parts of the trees, which have a tendency to become over-vigorous at the expense of the lower ones.