I have a cherry blossom tree potted and recently bought another plant that I set on top of the soil (when I water it, the water drains through to the cherry blossom tree) I tend to be a chronic waterer and haven't watered them in a few days, came in the room to check and water my plants and saw this around the soil. Is this fungus? Eggs? Any ideas? I recently purchased mosquito bites and mosquito dunks and applied it to all of my plants because of a gnat infestation, which for the most part is completely gone. Between applying all that and watering appropriately I didn't expect anything else to pop up. Just trying to figure out what this new issue is. Thank you!!

Fungus or mold would be my guess, but I can't tell from the photo.

Is it concentrated where drainage from the smaller pot would be most concentrated in the4 soil of the larger pot?

What was the smaller plant, did it have mold or very organic soil, and might it have had some build-up of soluble salts and organics before you set it on top of the larger pot and watered it? Was there mushroom compost in the small pot?

This is not experienced advice, just what I would do:

I would remove the smaller pot and set that where it will drain onto something that you don't care about, like an old Tee shirt or towel, and not draining into any flowerbed or vegetable garden. Flush it well, in case something coming out was "bad" (fungi, mold, eggs, salts, excessive organics, whatever). If it turns out to be something bad AND it came from the small pot, maybe re-pot that small guy and put the diseased soil into a plastic bag in the trash.

Then I would scrape away as much as I could from the larger pot surface. Maybe replace all the mix I could remove without hacking roots.

Once you figure out what it is, it MIGHT not be harmful, but until then, I would reduce the risk to the cherry blossom tree. The longer whatever-it-is stays in the cherry blossom tree pot, the more likely it will eventually make you re-pot the tree.

Could it be the Perlite that makes up the potting soil mix?

Did you check the underside of the other pot that you had sitting in there? That might give you a clue.

Looks a little bit too regular, round and uniform in size to be Perlite, to me.

I think I'd spoon it out of there, but put it in a jar or something so you can satisfy your curiosity - not to mention ours!

Btw, mosquito dunks and bits really shouldn't cure your fungus gnat problem, I don't think, unless you're putting them in the plant saucers where the water sits. They're meant to be put into standing water to kill mosquito larvae.

Some people use sticky yellow paper to catch mature fungus gnats.

I would rather make the soil surface unattractive by keeping it dry - add coarse bark shreds on top of the soilless mix.
Maybe bottom-water most of the time. Flush the pot sometimes.
And keep organic stuff out of the pots. Few organics => little or no fungus => no fungus gnats.

I'm kind of hoping the little balls are baby mushrooms from mushroom compost in the mix.
That would also explain fungus gnats.

We should ask:
Are the balls hard like Perlite or squishy?
Do they smell different from the soilless mix in the tree-pot, or the other pot?
Are they still growing rapidly? At all?
If you spoon a few into water, do they dissolve?

Mosquito bits/dunks (or other forms of BTi) can be effective for fungus gnat control/elimination.
http://www.summitchemical.com/...

That's the standard advice I've seen given for the past 4-5 yrs. I don't have any problems with them ever since I got away from using any peat in pots a long time ago.

The bottom of the other plant didn't seem like it was covered in anything- the white balls were a little firm and didn't dissolve in water. When I got home from work this morning I moved the pot and it seemed like there were just as many, if not more white balls with new little orange ones popping up. I can't really tell if there's a smell from them- there's so many plants that the entire room has a soil-y scent.

When I read the Amazon reviews for the mosquito dunk/bits it said they worked on fungus gnats too. One goes into the water and the other you sprinkle into the soil. I also bought a 100 pack of the sticky squares and they work really well! A review said to mix the dunk and water them with it- do you think it's hurting the plants to use it like that? I've only watered them with it twice since I've purchased it.

Here are the pictures for reference-

Hey, neat about the mosquito dunks/fungus gnats - ya learn something new every day on this wonderful site, huh?

I'm leaning towards the little white balls being a fungus of some type. It's probably not harmful to your plants, but if you let it propagate it will be on all your soil soon. As I said before, I'd scrape it off the soil and isolate it to see what comes from it.

Do the balls squish, then kind of bounce back? I've found styrofoam bits in the soil of purchased plants lately, masquerading as perlite.

I have had this same problem this summer. Twice I have been told by others that the balls were probably fungus but I am still open to the idea that they may be eggs. Or perhaps both problems simply resulted from me keeping the soil too damp. In any case, here is how I finally dealt with the gnats -- I kept my vacuum sweeper out, and each day I used the wand of the vacuum to vacuum up the gnats -- it is great at catching them mid-flight in the air! I also vacuum them up from the leaves and the edges of the pot. You do have to be careful not to vacuum up the soil of any tender seedlings though. It took about 2 weeks to vacuum up all the hatching gnats. Also, I made sure to also vacuum my rug after the gnats to there would be plenty of dust/cat hair on top of them to prevent them from escaping my vacuum bag. In any case, if I were you, I would try to make sure you do not let the soil stay to wet for very long. Good luck!

>> the white balls were a little firm and didn't dissolve in water.

>> this morning I moved the pot and it seemed like there were just as many, if not more white balls with new little orange ones popping up.

That makes me think "fungus" even more. There must be something for them to eat, either organic components in the soil, or some organic fertilizer.

(Touching a match to one might distinguish between Styrofoam and fungus: both would stink, but I would expect Styrofoam to flare up with oily black smoke that smells like petrochemicals. Or drop one into a little mineral spirits. Or drip a drop of gasoline onto one. Those would dissolve Styrofoam, I'm pretty sure. I wonder if slicing one open would reveal a mushroom structure?)

Yeah, I would scrape them away and replace the surface mix. Then think about encouraging a drier soil surface. If you ever re-pot the tree, maybe consider a less-organic potting mix, maybe one that holds a little less water.

If you have a lot of pots indoors, and the fungus only appeared when you set one small pot on top of the potted tree ... don't do that. It hints that something is different about the small pot - either it has a lot more fungus than anything else, or the runoff from it contains things that encourage fungus.

I would put that small pot outside since it "infected" a valuable plant, or at least scrape the surface and flush what's left a few times (i.e. flush out soluble organics).

You can flush a pot quicker and more thoroughly (with slightly less risk of drowning roots) if you set it on top of some toweling, old cotton socks or other absorbent fabric and let on flap dangle down 6-12 inches. The dangling flap is a wick that draws dirty water out of the pot, encouraging the mix in the pot to let some air back in between flushes.

Or take the small pot outside and re-pot it with clean soil-less mix. Maybe most soil fungi are not harmful, but as an undesired hitchhiker, it's a "weed".