Pruning Anatomy 101
Pruning Anatomy 101
Before pruning, it’s necessary to understand the parts of the tree you’ll be working with.
When it comes to a tree’s branches, the terms twig, shoot, branch, and limb can be used interchangeably; however, twig and shoot usually refer to younger growth, whereas limb and branch refer to mature growth.
Buds are dynamic. They are growth points—undeveloped, embryonic shoots that appear as little bumps along the branches. Buds can go dormant in the fall, withstand the adversity of cold, even frigid winters, and then come busting out in spring and perform on demand.
A bud will produce leaves, branches (with leaves), or flowers (which when pollinated yield fruit). This depends on what type of bud it is.
All fruit trees have two basic bud types: vegetative and flower/ fruit buds.
Vegetative buds produce leaves and branches with leaves. They are similar on pome fruit and stone fruit trees. Vegetative buds occur primarily on 1-year-old wood and also on older wood. One-year-old wood has only vegetative buds.
Vegetative buds are slender, pointed, and clasped tightly to the branch. During the summer, when the tree is leafed out, they are hidden by the leaves and difficult to identify. In winter, when the tree goes dormant, voilà, the buds are exposed. In dormancy, vegetative buds begin to fatten and become encased by bud scales (protective blankets) and take on a silver grey hue.
Flower/fruit buds produce flowers first, then fruit. They differ on pome (apples, pears) and stone fruit trees.
Apples and pears have compound or mixed buds composed of:
- Cluster of 2–6 flowers
- Surrounding circle of small supporting (subtending) leaves
- Short, weak shoot
Flower/fruit buds on pome fruit trees are plump and round, and protrude up from the branch. They occur primarily on lateral branches, but also on primaries, and only occur on 2-year-old and older wood.
Flower/fruit buds on stone fruit trees are solitary, having a single flower and a single fruit. They occur almost exclusively on lateral branches—either on short, brushy shoots or on long, slender shoots. As with apples and pears, they only occur on 2-year-old and older wood.
Different species of fruit buds have different lifespans. Knowing the longevity of a fruit bud is important in pruning, as you may wish to renew them periodically.
The geometry and architecture of a tree are not, and should not be, haphazard. Deciduous fruit trees are trained and pruned to articulated, specific forms. Pruning and training should be used in tandem; they go hand in glove. While deciduous trees can be grown to myriad specific forms, one all-important factor unites them. They are simply geometric forms that facilitate the number one priority in fruit tree culture: sunlight interception and infiltration, especially in the lower portion of the tree.
Remember, fruit is largely produced from one source—the sun. You can enhance a tree’s interception of that energy by pruning and training so the branches have good spacing, both vertically and horizontally. Of the total direct sunlight that falls on a tree, you need 50–80 percent of that light to strike all portions of the tree to produce and maintain quality fruit buds. In summer, when the tree is leafed out, this looks like what I call dappled sunlight—more sun than shade on the leaves. Sunlight does not naturally move (unaided) more than 3–4 feet into a tree canopy; at just 3 feet inside the canopy, light can be reduced as much as 60 percent. Thus, good interior light distribution relies on a tree form that allows alleys or shafts of light into the interior.
With pome fruit and stone fruit, by far the two most used forms are the open center (OC) and the modified central leader (MCL).
Of these two systems, the open center is much simpler in design and thus easier to master and teach. While somewhat more complex, the modified central leader has more fruit-bearing surface than the open center, and thus promotes higher yields per area.
The open center form mimics the geometry of a cone, with wide circular top and a relatively narrow base. Think of it as a sun cup: fill your cup with light; fill your life with fruit. A wide, open top with good horizontal spacing between primary branches creates alleys or shafts of light down into the core of the tree.
If you flip the cone or superimpose an equilateral or isosceles triangle on the tree, you get the basic form of the modified central leader. This form—narrow at the top and wide at the base—also achieves good sunlight interception and saturation into the tree’s lower portions.
More from Fruit Trees for Every Garden
Reprinted from Fruit Trees for Every Garden. Copyright © 2019 by Orin Martin and Manjula Martin. Photographs copyright © 2019 by Liz Birnbaum. Etchings and illustrations copyright © 2019 by Stephanie Zeiler Martin. Published by Ten Speed Press, an imprint of Penguin Random House LLC.
How to Select a Tree Planting Site
Learn what factors to consider when deciding where and when to plant a new fruit tree, including resources on find a spot with the best sun exposure.