By Luke Miller
Nature usually has things well in hand. But every so often she needs some help. Case in point: pruning.
Trees don’t always grow the way we want them to. Some species form multiple stems, which are inherently weak. Others start out just fine but develop problems after injury caused by people, animals, or wicked weather.
This sugar maple lost its top after a dry spell. When I cut the trunk back to live wood, the maple responded by growing multiple leaders. This is what happens when deer browse a tree, too.
When there’s more than one leader, things don’t usually work out well. It was true in ancient Rome. (Reference the intrigue surrounding the emperors when more than one wanted the crown.) And it certainly is true in the arboreal kingdom.
The solution was simple: Remove one of the leaders. In this case I removed the weaker stem and kept the straighter, more vigorous one. (Note that I cut off this weak branch on an angle rather than straight down. This results in a smaller wound that seals more quickly.) Although it looks strange now, the oddly shaped trunk will even itself out as it matures. More important, a large, single-stem tree is less prone to storm damage.
Another potential hazard: when a tree develops a v-shape crotch. The narrower the angle, the weaker the branch. That’s not much of a problem on trees with a mature height under 30 ft, but it can be a safety hazard on larger specimens. Think of it this way: A snip of the loppers now could save a call to a chainsaw-wielding arborist in 20 years.
Pruning is really about looking into the future. This small oak has an abundance of branches. Too many, in fact. There simply won’t be enough room for all of them to develop into limbs. So I snipped off a few stems to make room for future growth. In this case, I retained branches on all sides of the tree, making sure they’re connected to the trunk at various levels rather than one. This way the tree will be stronger and better balanced visually.
Note: to lessen the chance of beetles spreading oak wilt disease, avoid pruning oaks from April to August, when beetles are most active. Pruning in late winter is best.
What about multistem trees like this amur maple? It looks more like a shrub than a tree—and that’s as nature intended. Since it tops out at about 25 feet, the multiple stems aren’t likely to cause problems.
However, the structure looks messy because branches are going every which way. Crossing branches tend to rub against each other, leaving wounds that can become entry points for pests and diseases.
I removed the crossing branches and opened up the canopy. It looks better, allows in more sunlight, and keeps the branches from rubbing. All in all the maple will be happier and healthier in the long run.