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Location is Pacific Northwest (15 mi W of Portland, OR)

A 2-inch diameter branch broke off my backyard maple tree at the trunk this afternoon. The branch had many healthy-looking leaves and seed "helicopters" on it. The leaves show no obvious signs of disease or insect damage.

However, most of the wood was extremely brittle, as if it was dead or almost dead. The only parts with any flexibility were near the distal ends. Branches closer to the trunk end snap like dry kindling, and this is why the main branch broke off.

To my untrained eye there doesn't seem to be evidence of rot or disease, the wood is just very brittle and fragile.

Is the tree in trouble? The main trunk is about 24" in diameter but splits into two trunks about 8 feet above ground. I don't know how old it is.

Here are some pictures

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Closeup of trunk branching:

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Where the branch broke off, from the right side. In the first image this is hard to see, it's about 5/6 of the way up on the right-hand trunk and points straight at the camera, so it blends in with the trunk behind it.

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Closeup of the broken branch trunk end

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Another shot of the break, from the other side.

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As requested, a cross-section through the broken branch.

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  • where is the tree growing? what part of the world? Can we also get a look at the junction in the trunk where it splits? and a cross section of the branch that broke? – kevinsky Jul 11 '16 at 16:27
  • @kevinsky I've updated the post with much better images and location info. – Jim Garrison Jul 11 '16 at 17:04
  • Maple wood is strong but brittle somewhat like glass is strong but brittle. The dark areas in the cross-section are deadwood. The whiter wood of most of the cross section is live wood. The branch has been damaged ('dinged') a few times, but otherwise looks to have been healthy. – Jim Young Jul 11 '16 at 20:56
  • I did another cut 6 inches further out and there in no dead wood visible at all – Jim Garrison Jul 11 '16 at 22:31
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From what I can see, that branch is beneath the canopy, yes? It does have a bit of dead tissue. The reason is, from the information you've given and a few assumptions, this branch and its leaves weren't producing as much food as the canopy of the tree in the sun. Trees will get rid of (slowly) under-achiever branches and divert energy to the over-achievers. If there was a lot of weight at the end of this branch trying to get more sunlight that could easily explain why this branch broke.

Pruning branches that aren't producers will 'hurry up' the diversion of energy to the canopy. Otherwise the tree will get rid of non-producing branches all by itself. No big deal, very, very natural and normal.

When you see branches of a tree with NARROW angles to their main branches (the crotch between the two main trunks in your picture), that is a sign of a weak connection. The strongest connections are branches that have almost 90 degree angles to their trunk, main branch. Like Oak trees. Very strong connections. Maples not so much. Kinda against our intuition. The more weight of a branch, the better the connection. If that branch can get its photosynthetic 'factories' that make FOOD for the tree out far enough to compete with the canopy the connection will be even stronger. Your branch looks as if the tree gave it its walking papers, the pink slip?

I'd pull the moss off the bottom of that trunk near the soil. Be gentle. Moss will keep moisture up against the bark and bacteria could eventually girdle your tree. The rest of the moss, don't worry about it.

Send more pictures of your entire tree and a close up of the leaves, we could give you an ID and say more about pruning so branches don't willy-nilly break off. If you are worried, call your cooperative extension service with your nearest University. They might have Master Gardeners, Master Arborists in need of more points to finish their programs. Or hire one to come out and check the health of your tree, give you ways to increase its health and how to prune correctly...or do it for you.

  • Yes, the branch that broke was well shaded by the canopy and other trees nearby. And it was very heavy with leaves, so your analysis is likely correct. Thanks. – Jim Garrison Jul 12 '16 at 19:55
  • Good. Don't think you need to lose any sleep over it for sure. – stormy Jul 12 '16 at 20:01

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