To start the trees at four feet, the tops must be cut back to that height at the time the trees are set, or, if smaller, when they have grown to that height. Three or four buds nearest the top should then be allowed to develop and form the main framework of the tree. After this the trees will need little or no pruning, except the cutting back of straggling branches, and the removal of dead or broken ones. Some writers have advised the persistent and severe cutting back of the tops, from time to time, so as to keep them small, compact and low, but such a system of pruning must be put into practice on a considerable scale for a number of years before it can be recommended. Such a plan might prove valuable where the trees are subject to the force of strong winds, but otherwise it is of doubtful value. TIME TO PRUNE. Pruning may be done at any convenient time, but the best period is probably either just before the flow of sap in spring, or just after the trees have fully developed their leaves in spring. Following the removal of branches of any considerable size--three-quarters of an inch and upward--the wounds should be carefully painted over with white lead paint to prevent decay. CARE OF BROKEN TREES. When trees are broken or injured by wind-storms, the broken branches should be cut off and the resulting wounds carefully trimmed and painted. If the branches are only partly split off, the injury may be repaired, in many cases, by pressing the branch back into place and bolting it there, so as to hold it firmly in place. Trees with forked trunks should be protected by passing a bolt through the two branches some distance above where they divide to prevent splitting. NURSERY ROOT-PRUNING. Too frequently the root system of pecan trees, intended for planting, is but poorly developed. The root consists almost entirely of one large taproot destitute of laterals. Such trees are slow in starting and are hard to transplant. Figure 33 shows an excellent root system on a nursery tree. Such a tree should be almost as easily transplanted as an apple tree. A little more care on the part of nurserymen would insure good root systems. In a former publication it was suggested that the young seedlings intended for stocks be root-pruned "in the fall, after the trees are one year old. It could easily be accomplished by running the tree-digger down the row at a depth of nine or ten inches. The taproots could thus be severed, and the following spring, or summer, the trees could be worked (budded or grafted). This course of treatment would insure greater success in transplanting, as it would have a tendency to develop the lateral roots; and in addition to that, it would, in all probability, induce earlier fruiting." ROOT TRIMMING BEFORE PLANTING.