of Oxyporus corticola, but there are plenty on the web and here on MO..
Darn, I had forgotten about latemarginatus, it looks even better..!
If you get an opportunity to check this in the microscope, Oxyporus has characteristic cystidia with something like crystals on the top.
But it really resembles orange spore powder on the pore layer. I wonder if it could be conidia, but I don’t know which polypores that can have them (I haven’t seen it described in Oxyporus). If it is conidia, they are produced on the upper side or in the context, not dropped from the pores. Anyway, it should be easy to find out what it is in the microscope (or what it’s not..).