bobmct wrote:
Last summer I replaced the decking on my deck with 5/4 x 6 pressure
treated something purchased from a reputable lumber yard. All went
well. I did NOT put any type of stain or finish on it 'cause it was
pressure treated. Now, some 6+ months later and after the horrendous
NE winter we've had, there are black streak marks showing up on many
of the boards.
Any idea what these might be and more importantly how I "might" be
able to get rid of them???

Maybe iron stain from fasteners? I also thought maybe mildew but have no
idea if it will grow on PT; one would think not but...