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My indoor basil plant has been forming these brown beads on the bottom of leaves and on stems. I think it might be sap that's been oozing out that's turned brown / hardens when exposed to air.

In the photo, you can see:

  • the brown bumps on the stem (center)
  • the brown bumps / sap on the underside of a leaf (right)
  • sap (before it turns brown) on a leaf (bottom)

I also notced that a lot of the green leaves have tiny yellow/white specks (you can see it in the leaf at the top of the photo)

I've checked, and I can't see any visible insects / parasites.

Does anybody have any ideas what's going on? What should I do?

Brown ooze / sap on Basil

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  • Those brown bumps look remarkably like scale insects - try picking one off, or use a cotton bud dipped in white spirit, dab the bump and try to remove it
    – Bamboo
    Mar 30, 2017 at 9:34
  • Quick comment to anyone else stumbling upon this and who's about to pick them with their bare hands: The lumps are female scale insects that have died and hardened. They are full of eggs.
    – kiwibonga
    Oct 24, 2022 at 23:57

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It looks like a scale infestation. Unfortunately, Basil, being an edible plant, isn't that easy to treat because you can't use heavy duty insecticides, so its probably best to dip a cotton bud or something similar into white spirit or alcohol, dab the scale insect (the brown lumps) and remove them. There will be nymphs, the immature form of the scale, on the plant too though, and you can't use alcohol on the leaves to get rid of those. Neem spray might help, but wash the leaves before use. If Basil is readily available where you are, I'd bin this one, and get another, but otherwise, do the alcohol treatment and just use any healthy leaves you can see and struggle on. Some information on scale insect here https: Scale Bug – How To Control Plant Scale.

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  • Yes. That does not look like guttation. With just one plant, you might be able to pick them all off with tweezers. -Never tried that myself, but I grow a 2X3 meter bed of the stuff each year -LOTS of Pesto! Basil is tough if you've got some clean branches, you might get away with just cutting everything else out.
    – Wayfaring Stranger
    Mar 30, 2017 at 15:31

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