This section is from "The Horticulturist, And Journal Of Rural Art And Rural Taste", by P. Barry, A. J. Downing, J. Jay Smith, Peter B. Mead, F. W. Woodward, Henry T. Williams. Also available from Amazon: Horticulturist and Journal of Rural Art and Rural Taste.
But how best to attain this result is a question of difficult solution; if the soil is faverable and moderately enriched, the planter will for some years have more wood than fruit. On the other hand, if planted in poor soil, he may procure a few specimens of fruit from his stunted trees the second or third year from planting, but it will only be a few, and the production of these will further arrest growth, and the tree will require a year or two to recover the shock, if indeed it ever attain a vigorous condition.
Availing himself of the results which science has achieved when applied to practice, the impatient planter procures a plantation of (so called) dwarf trees, and again he fails to realize his anticipations. He finds that with all his vigilance he cannot prevent the borer from destroying his apple stocks. His peaches on plum stocks snap asunder at the junction, with a fine crop nearly ripe. His pears on quince die out by degrees without any apparent cause. Humbled by his losses he applies to high pomological authority for advice, and receives it. He is told that his course of culture was wrong. He applied nitrogenous manures when carbonaceous only were wanted. He should have treated with phosphartes instead of ammonia.
Turnips should have taken the place of his carrot crop between the rows of his trees. He committed a fatal error in mulching his ground, or, if opposed to mulching, preferring to keep a cultivated surface, his trees were no doubt injured by continued cultivation, and a slight mulching of tan bark would have probably saved them, and, that the finest pears as well as other choice fruits, are as easily produced as cabbages. And thus he is silenced, if not convinced.
The above is no exaggerated picture, although it might well be taken for such; all this has occurred, yet we kuow that the finest apples have been gathered from dwarf trees, that peaches have lived on plum stocks for thirty years, and that pears on quince roots have proved healthy and productive for an equal period; but the fact still remains, that success is very uncertain, even under the best treatment, in the culture of plants that are grafted upon stocks of weaker growth than themselves.
The object in doing so is to weaken and reduce the growth of wood, and it is but reasonable to expect, that an occasional case may occur where this proves too severe.
I have long been convinced that root pruning will ultimately supersede all other methods of inducing fruitfulness in trees, but not until we become convinced that fine fruit cannot be produced without skill and labor.
It is now nearly twenty years since I received my first lesson in root pruning. A row of plum trees that for many years flowered annually in the greatest profusion, but whose excessive vigor of growth invariably starved out the young fruit, so that it dropped as soon as formed, were operated upon. A circular trench was dug out about five feet from the stem, and as deep as the lowest roots; all the roots met with were cut, and all perpendicular roots were also cut as far as practicable without breaking up the ball thus formed. The soil was replaced, and without further care these trees afterwards produced yearly a heavy crop of fruit. I have often had occasion since to witness similar results. A few years ago I root-pruned a row of Nectarine trees trained on the inside wall of a cold grapery; previous to that they rarely produced a fruit, and I believe they have not failed in a good crop since.
Entire control over the roots is the great secret of success in the growth of flowering plants. Florists are well aware that a Geranium will flower most profusely when the pot in which it is growing is well filled with roots. The same principle is recognized in growing fruit trees in pots, and immense crops are produced.
The operation is so simple and the expense involved so very slight that no objections can be made to the system in that respect, and I would strongly advise those who have not been successful in growing pears on quince stocks, to plant healthy trees on pear roots, as I can confidently assure them that they can get fruit as early, and with much more certainty, if they adopt this method of culture.