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.

[rbarata]

I can't see clearly in the phtos but the fluffy substance, in my oppinion, it is not directly related with the mites. The fluffy substance can be fungus and/or fertilizer deposits.

Hydrogen Peroxide and orchids don't mix very well, especially on the roots. It will kill them.

An insecticide suitable for orchids might be a better choice.

[tjselwyn]

Thanks for your reply. I did fertilize it when I repotted it, so hopefully that's it - I'll look into fungus as well.

Yes, I've realised since posting that hydrogen peroxide is a very divisive subject. I'll investigate alternatives.

[estación seca]

The white stuff is probably mold growing on the bark. Fungus that live on dead plant matter don't usually attack live plants. I ignore it in my plants.

Bush snails can be killed with coffee. I would not throw away a plant solely because of bush snails. They are likely in all your other plants. Use the Search via the top maroon menu on "coffee."

Tiny bugs in the medium rarely cause problems for plants. I would ignore them unless you see root damage that looks like chewing. The root mass is an ecosystem with lots of normal residents we don't normally see.

Plantlets are often started in plugs of foam. They grow away from and out of the foam. That plug rarely causes problems, and meticulously removing it often causes root damage. I don't think it's a good idea to be aggressive in removing old potting media.

I think the best approach to growing orchids is to focus on providing proper light, water, temperature, humidity and air at the roots, and not worry much about other factors.

[tjselwyn]

Thanks, ES. Yes, the more I trawl through pictures and videos, the more convinced I am that the white stuff is snow mold. Most sites advise taking action against it, though: repotting and a course of something like Physan is what I'm reading. But would you suggest at least leaving it for a while to see how bad it gets?

I do regret the panic over the bush snails...I think it was those on top of the mites that took it over the edge. And I'm glad to hear you wouldn't stress about the bugs; I should probably also be encouraged by the fact that they don't resemble any of the commonly known ones that people advise dealing with.

Great to know about the plugs as well - I'd assumed clearing that out when repotting was ideal. I've never been overzealous about it, only doing what I can without damaging the roots, but I'll not get bothered about that in the future.

[estación seca]

I don't worry about the mold. I think that kind of mold is more prevalent at lower temperatures. I only see it on medium in my house, not in my warmer sunroom.

[tjselwyn]

OK, that's a relief. You've made me feel a lot better about it!