The habit of growth of a given variety will have a great deal to do with the number of seasons during which heading back will be practiced. Spreading varieties, such as the Drake (see [figure 8]), if making a strong, vigorous growth, should not be headed any longer than is necessary to start a sufficient number of main branches. Every opportunity must be given the trees of this variety to grow as upright as possible. Summer pruning of the drooping, undesirable branches wherever they develop, will help to increase the growth of the upright branches. By pruning as far as possible to inside buds, every opportunity will be given the trees to grow upward. If trees of such varieties make a poor, weak growth, a very heavy heading will force them to make a stronger and more vigorous growth the following season, provided any unfavorable soil and moisture conditions are corrected. Care must be exercised with these trees to prevent the downward growth of any of the branches by pruning them off during the summer, as suggested above. As soon as a strong, upright growth is started, no further heading should be done, but careful thinning by removal of undesirable growth should be continued.
Upright varieties, such as the Languedoc (see [figure 9]) and Texas, may require heading for a longer time than the more spreading varieties. It is necessary to force them to branch nearer the ground and they should be made to spread as much as possible. Pruning to outside buds and summer pinching will aid materially and make it unnecessary to head back after the first two or three years. Where this is not done, heading may be necessary at the end of the third and possibly to the fourth year if the tree is in rich, deep, moist soil. Another advantage of summer pinching and removal of water sprouts is that the trees are not allowed to develop a thick “crow’s nest” at the end of the stubs where heading back was done the previous winter, making the following winter pruning much easier. The habit of growth of each of the principal commercial varieties is shown in [figures 8 to 12], inclusive.
After the main framework is properly started, further pruning will be limited to thinning out the tree to keep it sufficiently open and to remove all dead, injured and interfering branches. Most of the growth after this will continue from the ends of the remaining branches and as the trees grow higher they will tend to branch more. All cross branches and those that are liable to interfere later should be taken out. All water sprouts should be removed unless they are needed to fill in undesirable open spaces.
As the trees come into full bearing and approach maturity, the vigorous wood growth will cease and will be replaced by a moderate yearly growth of wood which will gradually increase the size of the tree without making it unmanageable. Where trees continue to make excessive wood growth when they should be bearing, the trouble may generally be traced to unusually rich, moist soil, a condition which pruning cannot correct. It may be beneficial to stop pruning altogether for a few years, which will be likely to throw the trees into heavy bearing and thus stop excessive wood growth. After the bearing habit is once thoroughly established, moderate pruning may be done to get the tree back into proper shape.
Fig. 13.—Eighteen-year-old almond trees deheaded six feet from ground, in the Armstrong orchard near Davis. Stubs painted with white lead. Photo taken February, 1914. Compare with [Figs. 14 to 19].
Fig. 14.—Same trees as [Fig. 13], showing growth one year after deheading. Photo taken March, 1915. On some of the trees long stubs were left near the bottom of the trees from which new growth never started. Only a moderate thinning out of the new growth was done.
The mature tree should have its branches so spaced that sunlight may penetrate to all portions of the tree. This is necessary for the continued health and life of the fruit spurs in the lower portions of the tree. If the top is too dense, the new growth can only continue in the top and outer portions of the tree where sunlight can penetrate. When an adventitious bud does start in the center of the tree it immediately makes a strong vigorous growth to reach the sunlight far above. Such a growth is called a water sprout. If the trees are kept so pruned that the shadow on the ground during the greater part of the day is mottled with sunlight while the trees are in full leaf, the small growth may be maintained in the center and the bearing surface greatly increased. Where this is done the trees will not tend to grow as high as they otherwise would. Pruning of healthy, mature trees, therefore, will be limited to thinning out and removal of dead and interfering branches and water sprouts. Portions which grow too high may be brought down by removal close to a shorter and lower branch. By giving this treatment only to small portions of the tree during a season, the forcing of water sprouts may be largely avoided.
