I think pressure treated wood nowadays uses a copper solution which gives it that green color. I don't know about shomburkia but dendrobiums are sensitive to copper. What if he mounted it on a piece of cork and then put the cork on the post. That way if the roots don't attach to the post it will be easy to move.

I'll suggest that James, thanks...

hi

I grow phals and Brassia but mounted on cork when the roots reach around to the PT they won't attach!! I tried growing creeping fig on it and even it won't attach will grow over it but won't hold on . I also use tree fern which gives the advantage of epi ferns will sprout in it good luck gary

Considering the potential chemical issues with pressure treated wood, I would not recommend it. Cedar is a great, sturdy option. I found a box of cedar shingles for $10 at my local Habitat Restore.