It's awfully hard to diagnose accurately based upon only that description,
but I'd guess some sort of insect or mite attack.

My first attempt at a "home remedy" would be to spray the affected plants
thoroughly with straight isopropyl rubbing alcohol, repeating every three
days for about three or four times.

--

Ray Barkalow - First Rays Orchids - www.firstrays.com
Plants, Supplies, Artwork, Books and Lots of Free Info!


"eeyore" wrote in message
...
Hello,

Sorry I can't post photos, but I'm wondering if anyone could identify
what would cause a white, almost powdery look, on the top of the leaves.
This leads to yellow leaves or black blotches on the leaves and then a
dropping of all the leaves. Roots look fine, but not sure what chance I
have with nothing but roots.

Started with my phal's but is expanding to all varieties. Very hot
summer here so at first I assumed it was sunburn, but since it continues
into the fall, it has to be something else.

Hope someone can help, I'm not a scientific grower, just been having a
lot of fun buying orchids that have dropped their blooms for a cheap
price, and getting them to rebloom. I was doing great, until whatever
this is took over.

Thanks!