Fluffy white substance on bark plus tiny grey bugs

[tjselwyn]

In the last couple of days I've found a double-trouble issue with two of my orchids, a dendrobium and a mini phal: a combination of a fluffy white substance on the bark and the presence of tiny grey mites. I've done a lot of searching and can't find anything about these two things being present together - I've assumed they're related but could be coincidental.

Both of these orchids have been repotted, the dendrobium back in April and the phal a week or so ago. The dendrobium also had bush snails, which weren't present in the phal, and I panicked a bit and ended up binning it (it had a mushy bark plug stuck right in the middle of the roots that I couldn't get out, and I imagine that's where some of the bugs are coming from). I'd really like to save the phal if I can, though - the attached photos are from its medium.

The fluffy white stuff was only in the bark, not actually on the roots or any part of the plant above the surface. The mites are tiny, grey, elongated, have antennae, and they move pretty quickly (they don't look like any pictures of mealybugs that I've found). I couldn't get a good photo of those, but I've attached what I could and also arrowed one in the picture of the pot.

Also, the black bits on the roots weren't there when I repotted very recently.

For now, I've taken the phal out of its pot and sprayed liberally with 3% hydrogen peroxide. A couple more bugs have since come out of the very centre of the root ball. I've also cut away the blackened roots.

Incidentally, this phal lost a major leaf a few weeks ago, which turned yellow and fell off. I'd assumed it was because of too much light/sunburn, but now I wonder whether it was caused by any of this stuff.

Any suggestions on what these things are? My priority is of course trying to make sure none of my other orchids get infested.