Phal leaf with brown stripes and turn yellow

[moria0672]

Originally Posted by King_of_orchid_growing:)

How long has the Phal been in that shady location? Was it just recently placed in that shady location?

You are very wrong about the expanded clay not providing enough moisture. Expanded clay hold tons of moisture, it's just very difficult to judge visually at first glance.

Don't believe me?

Test it out.

Grab a container, fill it with water 1/2 way up the container. Add expanded clay to the water's midline. Remove the expanded clay without dumping the water, then measure how much water is left behind.

If it isn't sunburn, then that "constant humidity" may be the culprit, and it may be a fungal or bacterial infection.

I'm leaning towards it being a fungal problem.

Yes, as was already mentioned, Sphag doesn't provide the best air circulation to the orchid's roots. It does need to be loose.

Dear Philip, the orchid is almost one year in the same position, shady but bright enough for Phalaenopsis...never direct sunlight.
Regarding the compost...I have never said that expanded clay doesn't retain water or moisture, but didn't seems appropriate for the opposite reason...it retains too much water combined with bark (for my growing system).
For this reason I have changed with sphagnum moss...with few water, it remains humid for long time and never needs to be soaked.