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RIGHT NOW IS A GOOD TIME TO PRUNE FRUIT TREES
It happens every time I teach a class on pruning. When I get to the part about when to prune, someone in the audience quips, "Why didn't you tell me that six (or 3 or 9) months ago, when it was the recommended time to prune?"
Well, I'm telling you now, this is a very good time to prune apple trees. It's also a good time to prune most hardwoods -- this period of late winter, before spring bud-break, when daytime temperatures are comfortable and the absence of leaves allows you to view the tree's "skeleton."
I spent several hours in mid-February doing annual pruning maintenance on my eight apple and crabapple trees that will help them produce more fruit and mature with a strong and symmetrical limb and branch structure.
There is a paradox involved in pruning apple trees. Apple trees need pruning to prevent excessive and misdirected branch growth but at the same time, pruning stimulates new growth, which increases the need for annual pruning.
It is the habit of apple trees to grow sucker branches and water sprouts in abundance, partly in response to pruning. You can recognize water sprouts easily this time of year because they grow straight up in the air, sometimes adding as much as six feet of growth in a season. Water sprouts and sucker branches should be removed every year.
One of the primary objectives of pruning fruit trees is to keep the tree canopy open so air can circulate and sunshine can penetrate all major limb sections to help ripen fruit.
Many apple varieties have a bad habit of growing branches back towards the center of the tree that cross each other, causing wounds where branches rub together and a dense center that prohibits air and light to penetrate the tree's center.
Ideally, pruning should begin when the tree is very young and continue each year so the tree can be shaped in such a way that it grows strong and allows penetration of air and light.
Pruning apple trees is complicated by the fact that not all apple varieties have similar growth habits. My HaralRed tree has a more undesirable branching pattern than my two Honeycrisp trees. I have several Red Splendor crabapple trees that would -- if I didn't intervene with annual pruning -- become a tangled mass of water sprouts and criss-crossing branches.
In my Pruning Simplified book, author Lewis Hill writes that fruit trees are usually trained in one of three forms: central leader, modified leader, or open center.
Trees that bear heavy crops of large fruit, including apples and pears, are usually best pruned to grow with a central leader, or trunk, at least in their younger days, Hill says.
The modified leader method is initially the same as the central leader method, but eventually you let the central trunk branch off to form several tops, according to Hill.
The open center method allows maximum light to penetrate the shady interior but is not recommended for apples, he says, because it produces a tree with weaker branches.
The key to pruning apple trees, Hill writes, is to think sunshine and light penetration. Because of its tight branch structure, only about 30% of an unpruned tree gets sufficient light to produce abundant fruit, and another 40% of the tree gets only a marginal amount of light, according to Hill.
As mentioned earlier, late-winter pruning does stimulate some re-growth of branches to replace lost wood. A general pruning rule is to never remove more than a third of a tree's branches in any one year. In the case of apples, a better rule, based on my experience, is to limit pruning to 10% of a tree's branches.
Several years ago, a spring storm caused a large oak limb to fall on one of my crabapple trees, destroying about half the crabapple tree's branches. That tree has been producing hundreds of new sprouts and suckers ever since to compensate for the branch loss that occurred in the storm.
I've been asked occasionally about what to do with gnarly, old, overgrown and under-pruned apple trees. There is no simple answer here. I would ask, what is the objective? To grow fruit? Provide shade? Preserve a memory? Sometimes it may be best to remove the tree and start over with a healthy young transplant of one of the tasty new varieties from the University of Minnesota such as Honeycrisp or Zestar.
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PUTTING DOWN ROOTS:
A Delightful Blend of
Gardening Wisdom, Wit
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by Cliff Johnson |
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