Can anyone tell me what's wrong with my plants?

[mam288]

I'm wondering if anyone can tell me what's going on with these plants? One looks similar to ghuylar's post from a few days ago, could it be the same thing? False spider mites? I have have spider mites before and don't see any mites or webbing.

[Catpainter]

Very interested in responses.... I received a Dendrobium from orchids.com (don't get me started haha) that has leaves that look very much like your second picture, but the stuff WILL NOT come off so I thought maybe humidifier residue or something? plant is otherwise healthy and growing though, so maybe different that what you have there.

[Clawhammer]

What is your lighting setup? Potentially too much light / sun

[katsucats]

The brown leaf tips probably aren't anything to worry about in my opinion, as long as they don't spread. There are a few leaf spots (i.e. dark, round, sunken spots) that should either be removed or care should be taken not to splash water near them. The white stuff -- I don't know, sunburn or mites are plausible. I will say that white leaf residue from orchids I get from Norman's (orchids.com) or Andy's are probably some kind of fungicide or something. But that's more even and doesn't look like the pictures, I think. Whatever it is, that stuff doesn't come off.

[Roberta]

Consider washing those leaves with the white coating with soapy water. If there are mites, it'll tend to kill them (at least reduce numbers). If it is a residue, the soap will probably help to remove it. It may not resolve the problem but it can't do any harm. No downside, potential upside.

[rbarata]

About the leaf tips...might be a too dry environment (increase watering) or, most probable, excess fertilization.

[Roberta]

Leaf tips on the Oncidium, probably hard water or fertilizer buildup. Black spots, as long as they don't spread not worrisome either. Oncidiums and relatives tend to get ugly leaves. Just trim the ugly parts (with sterile scissors or clippers... the rules of hygiene are the same as always)

[estación seca]

Many Cattleya alliance plants have a thick, waxy cuticle. If plants have been grown with proper watering, and then the watering becomes insufficient for a while, the leaves shrink a little. The wax separates from the leaf and can look like fine white scaling. This might be your issue; I can't see the photos well on my phone.

[mam288]

Wow, lots of ideas! Thanks!

I was thinking the black leaf tips might be over fertilization so I stopped fertilizing several months ago to see what would happen. The spots seem to still be growing. Not that that rules our fertilizer as a possibility but it's some additional information. As for light, I do have them under some T5 lights but the leaves that look unhappy are sticking out from under the light into the room. I dont think they get much light from the fixture.

I'll give the other plant a good wash and see if anything improves.

[Roberta]

The black spots on the Oncidium leaves could be a minor fungal or bacterial problem that came from splashing water or cold water. Or water standing on leaves that then got hit by strong light. It seems limited to just a few leaves - you could just trim the affected parts. Or spray with something like Physan. I don't see anything that would require more aggressive treatment.

The brown leaf tips could happen from fertilizer buildup if the plant got dry for a bit (Oncidiums hate to go dry...) Again, seems limited to older leaves. This group of plants just seems to get this sort of thing easily.