What is this green spore on my drying oak?

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Forum topic by JohnMcClure posted 03-24-2017 02:01 PM 524 views 0 times favorited 5 replies Add to Favorites Watch
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251 posts in 784 days

03-24-2017 02:01 PM

Four months ago my FIL cut down an oak (not sure the variety, but I will find out). I took a few of his logs and cut them into slabs on the chainsaw, on a whim, planning to dry the slabs for 2 years and see what they become.

I checked on my slabs (kept in a garage, which is not climate controlled, but is better than you might think) this morning. On the sapwood of most slabs, I saw this green stuff. It scrapes off very easily – it’s just on the surface, and it seems to come off in a powder, like spores from some kind of fungus, maybe? And it’s only on the sapwood, as you can see in the picture.

What do you think it is? Is it a concern?

Background on the tree:
3ft diameter at base, and was still alive, but completely hollowed out from ground level up to an unknown height. The thickness that was still intact around the hollow was about 2 inches all around. Not a single bug to be found anywhwere in the wood; the inside of the hollow was fairly dry, crumbly, dark brown; but after you crumble a little off with your fingernail, underneath still very hard.
The logs I took were solid all the way through, about 14” diameter. Some, however, were punky in the center, as though the rot of the hollow were creeping up through the center and had just reached that log.
The bark is still on, and some of it has green lichen on it (source of the spores?)

FWIW my slabs are about 2” thick, 2 feet long, roughly chainsawed from logs. Endgrain “sealed” with spraypaint.

-- I'd rather be a hammer than a nail

5 replies so far

View avsmusic1's profile


273 posts in 829 days

#1 posted 03-24-2017 03:25 PM

is it safe to assume the garage is fully enclosed?
Any airflow or dehumidification?
What state are you located in?

View JohnMcClure's profile


251 posts in 784 days

#2 posted 03-24-2017 03:33 PM

The garage is enclosed, and has a sort of “closet” (no door) up against an interior wall, where I’m keeping the wood. This I expect keeps the temperature pretty mild. At one point I had a small fan circulating air in the closet, but unfortunately after I borrowed the fan I never put it back. And I had a 100W incandescent light bulb on for the last couple of weeks.
I’m in Texas near Houston, so the winter was not cold and it’s now summer with highs in the mid 80s. Humidity is… variable.
The slabs were stickered but as a matter of fact, I think the ones with the green spores were at the bottom back of the pile, so the poorest airflow.

-- I'd rather be a hammer than a nail

View Andybb's profile


1274 posts in 747 days

#3 posted 03-24-2017 03:47 PM

Here in the Pacific NW mold is a fact of life. A local guy here keeps a spray bottle with half strength bleach that he spritzes on stuff like that. I knew Texas was like another world. It only just became Spring here in Seattle! :-)

-- Andy - Seattle USA

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1403 posts in 1874 days

#4 posted 03-24-2017 03:48 PM

Texas summers start in March?? And I thought Arizona was bad with summers starting in June…. Ok, I’m done.

We don’t get a lot of mold here, but the little we do comes off with sanding or milling.

You beat me to it, Andy. ........... Jerry (in Tucson)

-- Jerry (in Tucson)

View Andybb's profile


1274 posts in 747 days

#5 posted 03-25-2017 08:26 AM

In answer to your question, no it is not a concern. It will disappear the first pass through the planer or sander.

-- Andy - Seattle USA

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