What are these marks on a Phal leaf?

[RosieC]

Anyone know what these marks might be?
Could it be mite damage, I've had spider mites on some Dens, but I've not seen mites on this, just these marks.
What else might it be?



A bit of background, this was only the second orchid I ever bought, back in 2008. Until a couple of years ago it was also a massive very healthy orchid, with over 32 flowers when it last flowered well in 2010.

However for the last couple of years it's health has been steadily declining. It's lost several of leaves which were NOT the bottom ones, mostly from one side. It's grown new leaves so still counts 13 leaves, however the new ones are pretty small compared to the old ones and most of the leaves are very wrinkled and limp.

I grow a lot of phals successfully (this is one of 23) and the others are doing well. I know how to look after the roots etc, but this one won't grow new roots (even with seaweed extract) and over the 3 years since it last grew roots most of them have just aged and died so there are very few left.

Anyway, I'm not looking for general care tips, unless you think there is something I might be missing, I'm just wondering if these marks could explain it's reluctance to be healthy