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Photo: N/A, License: N/A, Created: 2019:10:23 17:07:28

SUBMITTED PHOTO A pruning job from several years ago did not go as planned.

Unlike the case with “pruning” herbaceous plants—for example deadheading or thinning perennials, the marks of pruning woody plants remain, able to tell their side of the story for years, or even decades. So, sometimes trees give arborists the chance to go back and check their work. But just like when a good speech teacher tells you that your otherwise good speech was ruined by your milk mustache, if you are going to check your work with trees, you need to be ready to wrestle with bad news.

In some regards, the photo tells me some bad news. There are two signs in the photo that the pruning job I did several years ago did not go as planned. The easiest problem to spot is the two sets of adventitious sprouts near the pruning cut. Adventitious sprouts are the small tree-looking branches growing out of the trunk. These sprouts are response growths from latent buds and have neither structural integrity nor aesthetic appeal.

Latent buds are like the second string: If a windstorm or a tree guy takes out the starting quarterback, the latent buds are the bench that supplies his replacement. But even though in football, the replacement might be a Nick Foles, what grows from a latent bud on a tree will never take the tree to the Super Bowl.

The second problem in the photo is less visible. If you look closely, you can see that the pruning wound has never even begun to close up, and there is even a decaying stub remaining. An arborist’s goal when pruning is to cut the branch in such a way that the tree will naturally and quickly cover the wound and prevent further decay. In the photo, I do not see any wound wood, much less a “healed over” cut.

So, with both problems, shall I admit my guilt, try to learn a lesson, and try to blot this failure from my mind? Sort of. But as I have reviewed the case, I have reasons (excuses?) for my failure.

Here, then, are my excuses, and we can all learn from them. I was called to repair wind damage on this tree: A broken 10-inch limb. The Colorado State University Extension guidelines for pruning mature trees says that most pruning cuts should be less than two inches in diameter, and cutting more than four inches should be avoided.

Second, the same guidelines require no more than 20% of the foliage of a tree to be removed in pruning. But the limb on this soft red maple was broken, so I had to cut it. Third, pruning cuts should be at the growth collar, preventing stub or flush cuts. But major limbs often do not have collars.

The moral of the story is that with preventative pruning, many emergency pruning errors can be avoided.

Joshua Arp is an ISA-certified municipal specialist, Clarks Summit’s municipal arborist and an operator of an organic lawn and landscape maintenance business. Reach him at