Brown Rot is self-generating because removal of cellulose combined
with lignin damage creates a sponginess that is hygroscopic as well
as structurally unsound. Here you see the rotted area of this old
cedar fence post is at 29% MC on the “A” Scale of my moisture
Interesting and sometimes colorful little algae-fungus combinations
that are generally harmless and can be brushed off.
Mold and Ambrosia Beetles
find Blue Mold (or Blue Stain) without Ambrosia Beetles but you’ll
rarely find Ambrosia Beetles without the stain. Various species of
molds and sapwood stains feed off the moist sugars in sapwood and
discolor it in the process, often permanently.
can see bluish discoloration in the sapwood edge of a Douglas Fir
joist. As the joist was recently scrubbed with full-strength bleach,
the stain is permanent. You can also see a few bluish pin holes in
the sapwood from Ambrosia Beetles. These insects attack stacked logs
and downed trees still having intact bark throughout the warm months
of the year within as short a period as two weeks.
The adult beetles
bore through the bark into the wet sapwood, lay their eggs in the
tunnels, and depart. Their secretions plus the sugar in the sapwood
attracts Blue Mold development in the tunnels, which their larvae
feed on after they hatch and also eventually exit the log to
continue the cycle. In some woods the result is considered
attractive, and there is a market for “Ambrosia Maple” as one
Prevention measures include milling immediately in summer,
debarking or ponding logs waiting to be milled, including continuous
irrigation of the log stacks with water, which also inhibits other
fungi due to oxygen depletion. They cause little real damage and are
no further threat once Ambrosia affected wood is seasoned.
Carpenter ants come in small and large sizes and also don’t eat
wood, but use it for nesting. They require warmth and nearby food –
remove one or both to drive them away.