Almost lost a 30 year old oak because of a hidden root rot

I was out on a job last week in Blue Springs and noticed this huge oak looking a little thin on one side. The homeowner said it was fine. I poked around the base and found a soft spot about the size of a dinner plate. Turns out it was Armillaria root rot from a broken sprinkler line soaking the base for like 5 years. I found out from a forestry extension article that this fungus can spread 10 feet underground before you ever see a mushroom. By the time the canopy shows signs the root system is already 50 percent gone. Has anyone else caught something like this early and saved the tree?

3 comments

3 Comments

the_paul19d ago

That root collar excavation you did, was it mostly just removing the infected bark and dirt, or did you have to cut into the actual wood structure? I dealt with a similar situation and the arborist had me digging out about six inches of soil from around the base before we could even see where the rot stopped. Wondering how deep you had to go.

the_james19d ago

Jammed a shovel in about eight inches down before I hit solid wood on mine, same as you described, and @paigep20's story is spot on with how sneaky that fungus can be even when the tree looks fine above ground.

paigep2019d ago

Oh yeah I caught the same thing on a clients property last spring. The tree looked fine from the street but I noticed some bark coming off near the base. Scratched at it and found big white fans of fungus right under the bark. Definitely Armillaria from a clogged downspout that had been dumping water there for years. Sent soil samples to the county extension and they confirmed it. We did a root collar excavation and removed all the infected tissue plus improved the drainage around the trunk. Tree is still standing two seasons later and leafed out great this year. Caught it just in time the arborist said maybe another year or two and it would have been gone.