When all is said and done on the subject of pruning, it remains the fact that the real secret of fruitfulness in a tree lies at the root. If the roots are right the fruit will come - large fruit, finely coloured, and plenty of it. Can the same be said of the head? I trow not. Pruning the branches of fruit trees becomes a necessity when we have to grow them on the restrictive system to suit small spaces of ground; but were it not for that the knife might be kept away from them after the first early shaping without any harm resulting - in fact, with positive benefit.
In my nursery days - the nursery, be it understood, being one in which a rugged old fruit foreman acted the part of "nurse" - a, system of culture was adopted which has always seemed to me to be as near perfection as it is possible to get. Its point was root development. Every item in the cultural routine centred on this one thing. In describing the details of the practice to audiences, often largely composed of experts, I have been looked at with a surprise that bordered on incredulity when I spoke of a hole 6 feet across and barely 1 foot deep being left after the lifting of a tree only three years old. Yet in lifting the young trees to which I refer with the object of filling orders, the workmen began, perforce, 3 feet from the stem, because if they had begun nearer they would have torn to pieces a whole mat of fibrous roots. The roots of these trees did not strike down in the form of a few thick thongs; they ran along the surface in the shape of fibres - a perfect web of them. Of course, such trees as these were always well nourished, because the roots were near the surface, where the full influence of the air kept a constant store of food ready. They were pictures of health and models of cleanliness - no gum, no canker, no American Blight.
Now, how were these trees made to form a mass of roots? and how were the roots kept near the surface? Both questions are easily answered. They were induced to form fibres by being lifted and replanted, twice if necessary. If a young tree is lifted and put back again the second year after planting, the stronger roots are broken and exuberant leaf action is checked. Beyond paring over the ends of all broken roots with a sharp knife nothing need be done. The tree is simply taken out and put back again.
As to the surface action, it was not secured by any such antiquated and useless device as putting flat stones beneath the tree. We did not go foraging around the country and buying up surplus supplies of paving stones from indigent corporations that had overstocked themselves, and were in the way for getting a wigging from angry ratepayers. It was all a matter of culture. If I may be permitted a seeming paradox, the roots were kept up through being afforded every facility for going down. The land was very deeply trenched and thoroughly pulverised, so that you could press a walking stick up to the handle in it without much difficulty - admirably calculated, one would say, to encourage roots to descend. Well, they did not strike down, and for this reason: A soil that is thoroughly pulverised is a soil that is full of air and moisture. It does not crack through drought, because it is never dry. If it were dry near the top, roots would rush down to try and find moisture below; as it is moist near the top the roots stay there. The soil being full of air, the "solubising" (to coin a word) of plant food is in full progress, and the tree rapidly multiplies its feeding fibres in order to take advantage of the good things. In my experience, now approaching a quarter of a century, amongst cultivated trees, I have seen all sorts of devices resorted to for making them healthy and fruitful, from doing away with grafting to hanging bricks on the branches, or laying pavements under orchards; from tremendously hard pruning to no pruning at all. But none of them (harmless and amusing for the most part) ever got together so magnificent a lot of trees as those which I have been describing.
It follows from what has been said that simply chopping off so many roots from a fruit tree is not the be-all and end-all of root management. The first thing is to get the soil into the right mechanical condition for holding moisture through long periods of drought, and for permitting the free ingress of air. When this condition is secured by trenching, exposure to the atmosphere, and vigorous manipulation by spade or fork, early relifting will do nearly all the rest.
To come to details, a young tree should not be lifted when the growth is short and fruit spurs are forming fast, but a tree should be lifted when the summer growths are numerous, are 18 inches long or more, and devoid of fruit buds. Begin 3 feet from the tree, work carefully towards the stem, and as soon as fibres are met with delve down below the tree and work it out. The operation may be performed as soon as the leaves ripen in autumn, if the weather be showery and the soil moist; but if dry it should be deferred.
It may be objected that the foregoing remarks only have interest for those people who are starting with fruit, and that they are not of much value to the large number who enjoy a legacy of trees from a bygone generation. Such a protest would be reasonable. There are thousands of trees in the country of which the roots are in an unsatisfactory condition that are too large to lift, and may not be done away with. In this case it is well to make a trench round the tree so as to get at the roots, doing half one year and half the next, whenever a tree seems disinclined to bloom.
Root pruning is often carelessly done, the roots being severed by blows with a spade. A knife (or a small saw for very thick roots) should be used. It should be remembered that the growing roots of a tree are much softer than the branches, and a sharp pruning knife will easily sever any root up to 1 inch in thickness. Downward cuts should not be made. Upward cuts are better, because the fibres which push from them have a tendency to strike horizontally rather than downward (see B, Fig. 21).
In root pruning large trees a special effort should be made to cut strong roots striking obliquely into bad subsoil. These are often difficult to get at, as I know from sad experience, for they often plunge down almost perpendicularly at a short distance from the bole; but some of them ought to be attacked, as they are a terrible source of unfruitful top growth.
A, root system of an Apple tree showing procedure.
WRONG: a, root detached with a blunt spade, or in a bungling manner, the wood being jagged and the bark torn; b, root detached by a downward cut; c, root split by the improper use of the spade; d, root chopped off and both wood and bark bruised.
RIGHT: e, transverse or straight-across cut on a straight down root; f, slightly upward cut on a diagonal down root; g, upward cut on an oblique root; h, upward cut on horizontal roots.
The dotted cross lines indicate the proper direction and place of cuts on roots which have been wrongly detached.
B, results of wrong and right cuts.
WRONG; i, roots pushed from the under side of a root detached in a bungling manner, the upper portion dying back; j, roots emitted from a downward cut on the lower side of the root; k, roots pushed from a root split in lifting the tree, which root died back in consequence; l, roots emitted from a severely bruised root, which has died back considerably.
RIGHT: m, roots from transverse cut; n, roots from slightly upward cut; o, roots from upward cut on oblique root; p, roots from horizontal (or nearly) upward cut roots.
A, seedling Apple from pip or seed of cider fruit, and the plant a "free" stock: a, tap root or descending axis; b, lateral or anchor roots; c, fibres or active feeding roots; d, collar of tree or junction of roots and head; e, stem or ascending axis; f, laterals or side shoots; g, leading growth.
B, seedling Crab from pip or seed of wild Apple or Crab (Pyrus Malus), commonly called a Crab stock: h, tap root; i, side roots; j, fibres; k, collar; l, stem; m, side shoots; n, leader.
C, Quince from layer: o, side roots; p, collar; q, side shoots; r, leader.
D, Paradise Apple from layer, commonly called a dwarfing stock: s, lateral roots; t, collar; u, side shoots; v, leader.