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I have a small carambola that is growing indoors in a pot. I've noticed recently that it has tiny white bumps distributed unevenly on the upper stems. What are they: an insect infestation? A fungal infection? Or is it possible this is a natural part of the carambola's lifecycle (I don't know much about them, and this is the only live plant I've seen).

If it's bad for the plant, how do I treat it? The plant does not seem to be suffering (yet), but I would like to know what this is so I can deal with it before the plant starts to have problems. I started it from seed, and it was a lot of work, so I'd like to save this plant, if I can.

White bumps on carambola stem, finger for sense of scale

White bumps on carambola stem

I think I've seen something that looks like this on Virginia Creeper growing outdoors, and the vines always look healthy so I'm unsure if I should be worried about this - the carambola was outside for a while last summer so I suppose it could have picked up something a year ago.


Update: the bumps come off very easily if I run my fingernail along the stem. They don't seem to move on their own, so I'm guessing maybe a fungus? Or eggs, if insects?


Update: They don't seem sticky, like I would expect beads of sap to be.

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  • is it growing in high humidity?
    – kevinskio
    Jul 15, 2022 at 11:16
  • It's growing indoors. It's more humid now than in the winter, but I wouldn't say it's "high" humidity. Jul 15, 2022 at 13:18
  • I guess there is no satisfaction in knowing that according to Google you are the only person who has ever asked this question. I think they could be sap exuded by a plant doing a lot of transpiration
    – kevinskio
    Jul 18, 2022 at 14:19
  • @kevinskio I would have never guessed sap! I've had plants ooze sap before, but it's always been sticky, and usually clear, or clear with some colour tint (I have citruses and one of them oozed a bit last summer - it was sticky and slowly dripped down the stem and had the colour of amber). Jul 18, 2022 at 16:12
  • Nothing under "diseases" seems to describe what my plant is doing: plantvillage.psu.edu/topics/starfruit-carambola/infos Jul 18, 2022 at 16:14

3 Answers 3

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Google brought me here, I have the same white specks on my carambola seedling. Noticed similar specks on a papaya plant as well. Doesn't look like insects, if you squeeze the specs they are sticky so I think it is some kind of sap due to growing conditions indoors.

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mine are 6ft tall now. this only happens near the new growth. suspect some kind of relatively harmless edema. happens less if i water them less. growing them under lights indoors in the UK. relative humidity is sat between 50 - 65 percent and 18 - 25 degrees C.

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Due to the resolution of the photo it is a bit difficult to say with absolute certainty what the white dots are. The Virginia Creeper (Parthenocissus quinquefolia) is a climbing plant so the best guess would be that the white dots are new root nodes. However, if you feel there is something wrong then I would suggest spraying the plant with Neem oil.

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  • The white bumps I've seen on the Virginia Creeper didn't seem like new root nodes - similar to these they looked to be randomly distributed and came off easily (at a finger's touch, almost). But - they were bigger and shaped more irregularly. I'll keep any eye on this plant and if they come back (and if it' doesn't seem like sap), I'll probably hit it with either neem or Safer's insecticidal soap, and maybe tea tree oil (in case it's a fungus). Jul 21, 2022 at 14:45

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