Ray is correct, it sounds exactly like mites. There are many varieties, in
a spectrum of colors. Unless your eyes are a whole lot better than mine,
you need something stronger than the average magnifying glass to see them.
A jeweler's loupe might be a good option.

Repeated applications of the alcohol suggested by another poster will
eventually kill them, if they haven't gotten down into the potting medium.
Likewise, oil sprays such as Neem or Sunspray, if your weather is not too
hot for safe usage on those. But the applications must be repeated
regularly, and if the infestation is spreading as you describe, I would
recommend repotting all affected plants as you go along. Topical treatments
like alcohol or oil will not kill any of the critters that have gotten down
into the potting mix.

Effective systemic miticides are _expensive_ and hard to come by. Before
investing, you really need to identify the particular type of mite that you
have, because none that we've been able to find will kill all of them.
--
Kenni Judd
Juno Beach Orchids



"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!