From an experience long ago, a scary image returns to mind when I think about wet storms and trees.

Back when I was working for a tree service, doing consultations and estimates, the owner of a very large Monterey pine called for advice. The tree was beginning to lean during a period of heavy rains and gusty wind.

As we were standing near the tree, behind the lean, discussing a strategy for safely removing it, a couple of wind gusts got the tree rocking and it went over.

Fortunately, the fall zone had been evacuated. The only unmovable target was a cyclone fence, which the falling tree crushed.

I have seen worse, but only as aftermath. This one went over before my eyes.

This winter’s persistent rain has led to all kinds of tree emergencies. On a recent drive on rural roads I must have seen about half a dozen tree crews out cleaning up fallen trees, mostly on creek banks.

Occasionally, I get the opportunity to help prevent property damage from tree failures, as was the case on two recent occasions.

One incident involved an oak, probably 200 years old. The owner called and said the tree appeared to be leaning in a way it had not leaned before. In addition, roots behind the lean appeared to be lifting out of the ground. On top of that, a vertical crack had opened up in the trunk.

The limb structure was massive, with a large portion over the roof of a house.

A brief inspection revealed the anchoring roots behind the lean were indeed unstable in the wet soil. The crack in the trunk revealed weathering in the remaining thin wall of exposed wood—a sign that the crack had been there a long time. A four-foot long probe I inserted in the crack found nothing but an empty cavity to its full length.

On the opposite side of the trunk there was a less noticeable vertical crack in the bark.

I recommended immediate removal. By the time a tree service got to it, the cracks had opened further but, fortunately, they were able to get the tree down without incident.

The owner said it was a sad loss of a treasured old oak, but she was pleased that no one was hurt and there was no damage to the house.

Another incident involved a coast redwood, a species that rarely fails at the roots, at least in my experience.

This tree measured three feet in trunk diameter and was probably only about 60 years old. The owner had a feeling it was leaning more than it used to and thought something looked wrong about the base of the trunk.

Looking at the tree at a distance from various angles it was obvious to me that the top was leaning at about the same angle as the lower trunk, a sign of instability.

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In contrast, a tree that leans because of root defects or other factors, and then, over the course of a few years becomes more stable can show self-correction to vertical in the upper trunk.

Watching the tree closely, I could see a slight motion of the mid to lower trunk in light gusts of wind — not a good sign.

A careful look at the base of the trunk and the tops of the buttress roots where they diverge from the trunk, revealed a mushroom-like structure, located behind the lean.

Cutting off a sample, I noted it to be brown and leathery on top and finely porous on the underside.

I recognized it as an old, dry fruiting body of the “velvet top” fungus (Phaeolus schweinitzii). Often seen on various species of conifers, it causes a brown rot of the woody roots and trunk.

I considered it a high risk, as the tree was about 100 feet tall and leaning toward an occupied building located only 30-feet away. I recommended immediate removal and precautionary evacuation of the building if the lean or trunk movement increased before the tree could be taken down.

Sometimes, trees fail without enough warning to prevent property damage or bodily harm, but on occasion we get the opportunity to see signs of trouble and to take action.

Bill Pramuk is a registered consulting arborist. Visit his website, www.billpramuk.com. Email questions to infr@billpramuk.com or call him at 707-226-2884.

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