I adopted a fairly large (neglected) Hoya / Wax plant and ever since its been in my care it has had dappled white spots on the leaves. I always assumed these were the way the leaves grew - until a few minutes ago when I noticed that I could rub the spots off.

Am I correct in assuming that these spots are powdery mildew? If so, should I be treating it with dilute milk or something else? (Is this something I should just do periodically - I only water it at the base on a weekly basis, but it lives near a kitchen, and there is a lot of humidity - indeed I believe it survived ONLY on the humidity for many years until I adopted it)

Subsequent to @kevinskio answer I can rule out mealie bug and I don't think it is powdery mildew and its definitely not dust. I have now used a magnifying glass to examine an individual leaf, and (magnified) the white dots look almost like metallic silver paint splotches. Is it possible it is some kind of excretion from the leaf?

enter image description here

  • Much too spare to be powdery mildew. Mar 22 at 22:59

1 Answer 1


Every Hoya Carnosa I have seen has had these marks. A Google image search shows very similar patterns on many of the Hoya Carnosa that are pictured.

I have seem this described as a genetic disease but it could be a type of variegation. The problem in really answering this question is that there are many, many cultivars. Some show the same spots you observe and some show larger spots typical of variegation.

You mention that some of the spots come off. Is it possible that there is dust stuck to the leave from a previous use of milk or leaf shine?

Unless you see white cottony tufts which would indicate mealybug no action is called for. You could give the plant a good shower to wash off any dust and leave it at that.

  • 1
    Thank you for answering/engaging. I can confirm that the dust is not due to previous use of milk or leaf shine - I can say this with confidence as I've noticed that even the new folliage on my (rooted) cuttings - which I nurture in my office - are exhibiting the same white spots - also removable - and have definately not been exposed to milk or leaf shine. The newer leaves also have some of whatever this is, but quite a bit less of it. Its not cottony or mealie bug, and its not dust.
    – davidgo
    Mar 23 at 6:30

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