Actually, the wood was under a few conditions that may have cause both
the CCA leaching out and fungal attack.  The pine 4x6 was about 4" off
the ground, and the previous builder put plastic between the timber and
the fir floor boards.  Then there was the bases of the columns that were
sitting on the deck, covering about a 10" by 10" area.  The building
sits in a wonderful grove, allowing the moisture to sit, and sit.....
The fir was rotten under the bases, then under the floor the corners of
the CCA treated lumber were rotten.  It was more of the looks of brown
or soft rot, where the wood just turned to powder.  So I assume the
treatment had leached out, and the CCA pine just degraded naturally.
Oh, it was about 20 yrs old.

i hope to cure this problem by perhaps blocking the bases up about 1/4"
with Brazilian mohog? between the bases and the fir, and not put plastic
over the framing.  Also, I may apply Amteco, an anti fungal wood
preservative, to keep the deck from absorbing as much moisture.  The
trees around it may also be cleared a bit, so perhaps this may not
happen again.