Hope someone can help. I have issues with Calathea ornata sanderiana, it has like small crystals on all leaves. It is on both top and bottom of the leaf. I've not been successful in finding what this might be.

Hi and welcome to NGA!

A few questions to see if we can figure this out.

First, do the 'crystals' easily wipe off like dust or are they firmly attached to the leaves or actually part of the leaves? Second, is this appearing on new growth or just old growth? Third, do you see anything on the plant that look like very fine spider webs?

In the mean time, if possible, I'd take a damp wash cloth and wipe the leaves clean - don't forget the stems. Then watch the leaves and see if it returns.

Mineral deposits maybe? Have you tried to remove them, by saying, by giving her a good spritz? I'd give her a shower, just my two cents. And I'd go from there if they reappeared.

Judging from the irregular distribution of the white specks and the brownish leaf tip edges, I suspect spider mites. If so, spray the entire plant with a solution of soapy water, making sure that all leaf and stem surfaces are dripping wet.

Hi,

Thanks for answers.

@Xeramtheum Crystals are not firmly attached, no spider web, just crystals along the nerves of the leaf. There are no new leaves for some time now, so I have changed the soil and the place to see if this will make the change.

I've clean the leaves with a damp washcloth and they look on now but I would really like to find why this happens.

@Faridat maybe, but do you know why this happens?

@WillC no spider mites, I have encounter them before. This looks like a physiological issue and would really like to find out why this happened.

Thanks,

Calcium oxalate can be released from the leaves' pores and when it dries it takes this crystal formation.
https://en.wikipedia.org/wiki/...
This is another useful link, the phenomenon is not so rare.
https://en.wikipedia.org/wiki/...

Or, if you live in an area where the water is salty/brackish, I did a research and it has occured to other Calathea plants, excreting excess salt from the surface of the leaves. That's a remarkable phenomenon!

Hi, I am new here, so I am not too sure what I am doing.. I was wondering about your calathea issue. Have you concluded what the white dust was? I've had a similar issue on my calathea Maui Queen, and in the end the plant died. I was convinced it was not the mites, as I could not spot any webbing or any insects.. but maybe some sort of stress related issue due to the winter season and the impact of central heating.. but maybe it was the mites?

emapra5 - the answer to your inquiry is explained right above your post.

Have you looked at it with a hand lens?

I have been having the same problem with my Calathea Rosea and Calathea Ornata. Warning: this thing spreads from plant to plant. This took me a while but I finally figured it out. I saw microscopic white dots on the leaves and examined under the microscope. Please see the attached image (enlarged x80). These show as small white dots on the midrib of the leaves. Now that I know it is some kind of a microscopic insect, I will give the plants a good wash and apply insect killing soap a few times over the next couple of weeks. This probably won't help the original post owner but maybe it will help someone else.