The intermittently warm days that we have enjoyed lately are tempting gardeners to get growing even though those kinds of days are intermingled with wintery weather. We look out at the fruit trees and wonder if it is time to get out and get the pruning done.
The answer is yes and no. Yes, March is a good time to do the pruning but there is no hurry to get out there when the weather is nasty. Give a good day a chance and then face the project.
Before you find your pruners and saws, take the time to learn how to do your pruning correctly. The decisions for pruning cuts are based on the reasons for doing them. Pruning fruit trees serves several primary purposes: to train trees, invigorate them, make them more productive and keep the tree confined to a size and shape that you can harvest. It will produce a strong enough structure to bear a full crop of fruit and will be able to withstand the adversities of snow and wind. It will also collect sunlight to nurture the plant while it produces sweet, large fruit.
Training trees to fit these purposes is essential for a productive back yard orchard. Begin shaping and trimming the tree the day it is planted and keep up with it annually. Let the tree go for several years and it will grow too tall, develop long lateral branches and become bushy and dense so that sunlight cannot penetrate the interior.
Different types of fruit trees have different pruning requirements with some requiring little attention and others requiring considerable trimming. Never remove more than a third of a tree’s branches — even on those that require heavier pruning — as it will stimulate too much new growth and weaken the tree. If you have a tree that has become overgrown and needs extensive pruning, spread the work out over several years. Fruits with multiple seeds, such as apples and pears, are the pome fruits. Pome fruits form on a two year cycle. The first year, buds form and the second year the fruits differentiate. The fruits form at the end of a spur — a separate, small, woody twig attached to the branch. Those spurs continue to grow longer and produce fruit every year. Protect spurs for best fruit production. Spur-type apple trees develop long limbs with only a few side branches and many fruiting spurs.
Peaches, apricots and other stone fruits grow on stems that are attached directly to the sides of branches. They form on oneyear- old wood. Encourage and develop spurs on pome fruits and constantly cut stone fruit trees to keep an adequate area of prime fruit producing wood. On any pruning job, begin by removing plant parts damaged by diseases or insects. Next, remove crossing branches and those that rub on one another.
Remove branches that are weak and unproductive or hang down as these will not produce good fruit if at all. Remove water sprouts (long, fast-growing branches that go straight up with wide distances between the nodes) and suckers (sprouts that extend up from the root). Remove branches that overshade other branches, the center of the tree, or those that grow toward the center of the tree. Make all pruning cuts next to the collar (the wide portion of the branch that spreads where it attaches to the trunk or other branches). Do not leave a stub and do not cut into the collar because it will not heal over properly.
There are several systems that promote healthy tree growth and good fruit production. By their natures, some trees need more extensive pruning than others do. Some respond best to one system of pruning and others flourish under another. The modified leader system is ideal for semi-dwarf or spurtype apples and pear trees, which do not need excessive pruning. This system leaves one main trunk with tiers of branches spaced vertically along it at relatively even intervals. To train a tree to this system, cut the newly planted tree back to 30 inches high — just above a healthy side branch or bud.
Watch to be sure that one central branch grows up as a new trunk through the season. The lowest tier of branches should be 24 to 48 inches from the ground, extending out in four directions as nearly perpendicular to each other as possible. The next tiers of scaffold branches should be spaced 18 to 24 inches apart vertically up the trunk. They should also come out in four directions perpendicular to one another, but ideally, they should be spaced between the lower tiers if possible. Continue developing tiers until the tree reaches the desired height. Generally, the tree will have about three layers of branches and will be about 15 feet high. The branches should form 40 to 90 degree angles with the trunk. If the trunk angle is too narrow, put braces between the branch and the trunk to force them apart and widen the angle.
The number and spacing of the branches and the height of the leader varies with the type of tree — semi-dwarf, dwarf, apple, cherry, pear or plum. The open center system is ideal for peach trees and apricot trees. Keep these trees low for easy picking, spraying and pruning. About 18 to 30 inches above the ground, the branches extend from the end of the trunk.
Develop three or four scaffold branches, all near the same height on the trunk and spaced as uniformly as possible around the tree. Keep these about the same size by pruning. Do not let the branches develop sharp angles with the trunk or they will be weak and split under a heavy fruit or snow load. Prune so that the branches spread out from the trunk to allow light to the center of the tree. Although these pruning systems are best adapted to certain tree types, if you find your tree was shaped to a different method, continue with it. Do not try to change it.
Peaches and nectarines generally require the most pruning, followed by Japanese plums, apples, apricots, sour cherries, European plums and sweet cherries. Sweet cherries require very little pruning. They are large trees with long, upright branches by nature, so do not try to control growth by pruning. Pruning too heavily encourages the growth of water sprouts — long, willowy branches that grow straight up, shade the tree and do not produce fruit. Prune off branches that are interfering with one another or growing too close together. Watch during the growing season and if upright sprouts grow too long, clip them back to a bud facing the direction you want the tree to grow to encourage side branching. Generally, prune pie cherries to the open center system.
These trees are quite brittle and tend to grow at very narrow angles. Train the branches to wide angles while they are small. Train apricot trees to either the open center or the modified leader system. They do not require a great deal of pruning. Because they blossom early, spring frosts often limit fruit production. You may wish to delay pruning apricots until after they blossom.
Linden Greenhalgh, county director for agriculture through the Utah State University Extension Office, has announced that the USU Cooperative Extension Service will host two pruning demonstrations free to the public tomorrow. The first, at 9 a.m., will be at the home of Jay Cooper, 984 Ironwood Road in Erda. The second will be at the home of Gary Fawson, 187 N. Waterhole Way in Grantsville. For more information on these demonstrations, contact the USU Extension office at 277- 2400.