Sapwood in shiitake logs
When I was reading up on
inoculating logs with shiitake mycelium, recommendations on log sizes
varied widely, ranging from 3 to 12 inches in diameter. Large logs tend
to fruit longer and to hold moisture better during dry spells. On the
other hand, small logs fruit faster and are easier to wrangle
(especially if you plan to soak logs to force fruiting).
One factor I didn't read about, but soon thought of once I started looking at the logs Mark cut for me,
is the sapwood-to-heartwood ratio. Shiitakes only eat the sapwood, the
pale-colored wood around the outer perimeter of the log. And bigger
logs, especially if they grew slowly in woodland settings, might have
three quarters of their volume made up of useless heartwood, leaving the
fungi far less food than you might think.
In case you can't pick
out the sapwood in the first photo in this post, here's a labeled
diagram to get you started. This log has been sitting around for a
couple of weeks --- the color difference is even more evident in the wet
wood of a newly cut log.
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Looking closely at my
logs got me thinking that maybe the puny 3-inch treetops that I had
earmarked for firewood are actually better mushroom logs than these huge
logs that I'd originally considered prime fungi fodder. In fact, the
smaller-diameter logs have no heartwood at all, so they might contain
nearly as much sapwood as the log pictured above. Assuming I'm willing
to keep logs moist over the summer with sprinklers, perhaps little logs
are the way to go after all?
The decision will have to
be made soon because spring weather is finally upon us! Highs in the
forties and lows in the twenties means it's finally safe to pull the mycelium out of the fridge and inoculate those logs. Time to enjoy the March Into Spring!