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What is this on the back of Monstera leaf?
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What is this on the back of Monstera leaf?


I just discovered this brown substance on the back of one of my Monstera leafs. See the second picture for more detail. Looks like dirt or soil almost.

Never seen anything like it on my plants. It's the only leaf on the plant with this, and I see no bugs in the plant.

Anyone having an idea what it is?

by andreasrolen

30 Comments

  1. meedliemao

    Not sure what that is, but I’d remove that leaf asap before it spreads. You might want to look up “monstera scale”; it’s bugs, but you might not see them other than the ‘dirt’ they leave. There are treatment options for scale, so the plant will recover. Again, I’m not sure that’s it, but if you look it up it might help with a diagnosis.

  2. andreasrolen

    Some help from ChatGPT suggested “Rust Fungus” which I think it is.

    Removed the leaf and getting some oil to put on the other leaves to avoid it from spreading.

  3. MSenIt4Life

    I don’t know either but looking at the rest of the leaf it appears to have some kind of white specks and what looks a bit of scale on the stem. No clue what the rest of the plant looks like, but would cut this one completely off if you can.

  5. nowuff

    Is this a powdery substance almost like coffee grounds?

    I’m not sure I agree with other commenters that it’s scale. But I could be wrong. Scale usually shows as small waxy lumps that are difficult to remove.

    I’m guessing if you wipe this away with rubbing alcohol, there will not be anything there besides a yellowish spot.

    To be safe, I would cut the leaf off. But I wouldn’t ring alarm bells on scale just yet.

  6. Moxiefeet

    Where is that opossum hissing when you need it!

  7. Emergency-Advisor192

    It looks like a fugal infection. Cut off the leaf and treat with captain jacks. Spray down the whole plant and move it away from its light source so it doesn’t burn. Get a fan and install some good airflow.

  8. Faloopa

    You win: I made the actual Stinkface with my actual human skin and muscles when I saw this pic.

    I have tons of Monsteras ranging from 6 months old up to 40+ years old, and I’ve NEVER seen anything like that. Good on ya for removing that leaf and watching the plant, but I would also quarantine the FUCK out of it. Like in its own room and be careful not to brush up against it with your clothes and wash your hands before touching ANYTHING else.

  9. knightgimp

    kind of just looks like dirt caked on? did you get this plant recently?

  10. Cottoneyejill

    Rust fungus- mine had this after last years repot… chopped affected leaves, applied two treatments of neem oil & boom we good bb

  13. slyfox7187

    Looks like Rust. What does the top of the leaf look like?

  14. MzDarkChocolate1

    Eww take it outside with some solution and spray it off,

  18. EntertainmentOk3006

    I shall be inspecting every inch of my monsteras after work thanks to this pic. May the force be with you 🫡

  20. Disastrous-Hope7915

    Rust fungus, cut all affected leaves and apply an antifungal treatment or neem to prevent further spread.

  25. PearlyPilea3

    Rust fungus. I wiped the spots with watered down dawn dish soap every few days until it finally went away.
    Do not try to shower the entire plant off with water, it will only spread to other leaves. I made that mistake and it went from one leaf to all of them. If it’s just that leaf, it may be worth just cutting it off.

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