Discovered a 50 year old oak had root rot after a storm last Tuesday in Portland

I was out checking a client's property after that big wind came through and found the whole root system was mush underneath, which made me wonder how many of my other jobs have hidden decay I'm just not catching.

4 comments

4 Comments

morgan_bailey932mo ago

That "hidden decay" part really hits home. It's not just oaks either, I've seen it in maples and firs that looked fine from the outside. The thing is, by the time you spot visible signs like mushrooms or cracked bark, the damage is already way advanced. Most arborists use a rubber mallet to tap the trunk and listen for a hollow sound, but that's not foolproof. Some guys are starting to use resistograph drills to check core samples without hurting the tree too much. It's pricey equipment but beats losing a whole tree or having one come down on a house.

hayden1442mo ago

The tap test is pretty reliable if you know what you're listening for, but a resistograph is definitely the next level. I'd trust that over just tapping any day.

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sean7821mo ago

Throw a probe in your bag too.

mary_foster921mo ago

Good point about the tap test but "pretty reliable" and "if you know what you're listening for" are doing a lot of heavy lifting there. What's your personal batting average with it? I've had two oaks this season that sounded solid with a mallet but turned out to have decay pockets up high in the canopy, so I'm wondering if the tap test misses damage that's not right at the base. Do you usually combine it with something else, like poking around the root flare with a probe, or is the mallet your main go-to?