I picked up this plant from a plant shop in Phoenix. This white scaly stuff seems to be spreading. I had a second plant just like this that had much more growth on it and it eventually died. I'm really hoping to save it.

Any idea how to treat this or what it is?

a busy cat

  • it does not look like mealy bug but has a resemblance to powdery mildew which is uncommon on indoor plants with a waxy cuticle
    – kevinskio
    Feb 7, 2016 at 23:08

1 Answer 1


It looks vaguely similar to scale, but I really don't know.

I suggest that you dip a Q-tip in isopropyl alcohol and then touch a few of these spots. If they fall off you know it is scale or some similar bug.

You can treat the whole tree by taking it outside to spraying it with NEEM oil (at the label prescribed dilution). One spraying will wipe out most if not all of what you see. Be prepared to repeat the spraying again in one to two weeks time as eggs laid by these guys will have hatched.

If the Q-tip test doesn't have any effect, it might be fungal/bacterial. Again I don't know what it might be, but spraying with hydrogen peroxide will kill most fungi and common horticultural bacteria. Dilute at the rate of two tablespoons of 3% peroxide per one quart of water.

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    It's common name is Silver Thicket, so it's supposed to have a white bloom on it, to reflect light in it's natural harsh conditions. Wash the bloom from some plants and its doesn't return. Could the scaly patches be damage done by frost or another source of damage with the cuts drying out and scaring over? Is it possible there is another source of care that caused the other to eventually die e.g over watering?
    – user13638
    Feb 8, 2016 at 6:47
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    Roots must get oxygen. This is the reason for the 'well drained soil' mantra. I wait until the soil feels dry to the touch before watering. If you drag your finger across the surface, no soil should stick to it (alternatively you can ram a chopstick of the like into the soil and check that it isn't damp before you water again).. Then I water. I prefer to flood the pot as I believe this will completely refresh the gasses in the soil. Of course the problem could be any number of things. I'm just trying to help you work through solving the problem..
    – user13580
    Feb 8, 2016 at 7:02
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    That's the same process as I go through Jim. There's always the well meaning person who will water your plants on a weekly basis whether they need it or not, and then they drown! The compost in the picture above looks free draining though.
    – user13638
    Feb 8, 2016 at 7:05
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    Rosie, Now I remember. You are in Germany and must be growing this tropical euphorbia indoors. Since I again have no idea about which I speak, have you consulted on-line resources such as euphorbia-international.org/euphorbias/pests/…
    – user13580
    Feb 8, 2016 at 7:23
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    Not me Jim, it's Jterm's question I've grown in in the uk before, must try to find another one soon, now I have a greenhouse
    – user13638
    Feb 8, 2016 at 19:11

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