What kind of mold is this and how to treat it?

[AaylaSecura]

Hi,

I’m new to the forums and to orchid care in general. I have a phalaenopsis which I bought about 3 months ago. I noticed that the top of the roots and the medium are covered in some white dust. Is it snow mold or something else? Do I need to repot it and if I do repot it should I sterilize the roots? If so, what should I use? Can I use hydrogen peroxide (at 3%)?

Also the roots and the medium are stuck together: when I removed a few pieces of the bark from the top I think I damaged the root a bit, it was just glued to the bark.

See the attached photo.

[Roberta]

I don't see any mold. the outside of roots are naturally white. As far as roots being stuck to bark, they're behaving normally... in a perfect world they would be attaching themselves to the side or branch of a tree. When you repot, don't worry about removing stuck-on bark. Just remove what comes easily and leave the rest - preserving roots is what is important.

[Mountaineer370]

First, welcome to the Orchid Board! As far as your photo, I don't see any mold, either. Phalaenopsis roots are usually whitish or silverish when they are ready to be watered. Also, I see one root that looks like it is older and has turned brown, but it could still be viable, so I would leave it be. I see a couple of bark chunks at the top that look like they may have a whitish powder on them. It could be something like dolomite that was added by the manufacturer, or it could be mineral salts that have leached out of your water. It's just one photo, and it only shows a small part of the plant, but I'm not seeing a plant that is in dire need of repotting.

[Ray]

A white, dusty deposit could be minerals left behind by evaporating water...

[estación seca]

Welcome to the Orchid Board!

Those roots look typical for Phals being grown in a home during the winter. Mold tends only to grow on dead plant tissue.

You can learn a lot about Phals from a thread here. Go to Forums in the left yellow menu, then Beginners. Near the top click on The Phal abuse stops here.

[Orchidtinkerer]

hi aayla,
the white dust is mineral deposits. This is fairly normal but it can be a sign you might be overfertilising. I see it with lecca but not very often with bark - so it could also more likely be a sign you are overwatering slighly. Since you don't want to be keeping the bark soaking wet all the time the top layer should be dry most of the time, if it is not over time salt deposits will form more.

The general consensus on this board is not to use 3% hydrogen peroxide. If you have nothing else on hand and must use it then dilute it about 5 part water to 1 part HP but I see no need for you to use it.
Most problems can be resolved by drying out any rotting or molding parts, so HP is rarely needed.

A repot shortly after buying a new orchid is a wise move, mostly to check what the roots look like inside the pot. It sounds like the plant has not had a repot in a long time(roots all glued to bark) so yes check what the roots look like.
To minimize damage, fill a bucket with lukewarm water and let the whole pot soak in the bucket for 30 minutes.
This will loosen the bark and make it easier to peel off gently. If the bark does not come off easily it does not need to all be removed! Just remove any squishy bark, firm bark can remain for another repot.
Massage all around the pot first to loosen roots stuck to the pot, then gently pull the plant out.

[AaylaSecura]

Thank you all for the replies, I feel relieved to know it’s not mold! I’ll decrease the fertilization frequency.