BCSS - Forum

This spring and summer about half a dozen cacti have developed something: they turned completely orange in a short space of time. I have a few others which have developed orange localised spots, but these plants seem to have something different. The entire epidermis has turned orangey brown. I can't believe it is something like red spider, I would think it is more like bacterial or virus.
I grow my plants in house on windowsills, but in good weather I put them outside on the lawn. The result is generous flowering which is what I wanted to achieve, but I am concerned that I may have inadvertently exposed the plants might be some general garden diseases. Whatever it is does not seem to affect the cacti generally, I think a few species are vulnerable rather than my cacti.

I also have a second disease which has affected three Mammillaria species. The new growth has come "nuda" or "inermis", I do not know if this is temporary or a permanent change, but there are no spines on the new growth.

Please any advice about the above would be welcome. It looks like the rust covered plants will have to be thrown out.

A picture will be helpful.
Could be burned by the sun, if it happens fast and they colour reddish / orange?

I tend to agree with Aiko, especially if they are still very firm to the touch and not rotting. Even if they were originally on a sunny windowsill, moving them outside straight into direct sun can be problematic. Sun may seem the same wherever it is, but glass filters out a lot of the UV and the sudden exposure to high UV levels outside can scorch plants very easily. You don't generally get a suntan sitting in front of a sunny window!

Thank you. I will take some pictures if it helps, but the verbal description does sum it up. The reason I did not think sun burn is that the colour change was fairly rapid, and I regulate the position of the plants regarding the sun, when both on the windowsill and the outside. (In trays with sides marked for consistent placement) The orange is total and 360 degrees, that should not happen if it were sun burn, I would expect the orange to be on one side, also it is just a few plants out of two hundred. When I have had sun burn, rarely, it has been on a prominent patch of a plant.

Interestingly this is happening to my Echeveria Agavoides and one Echeveria (my only flat leaved form).

The tips start turning orange and then the whole leaf turns orange till it dies. Threw out one other plant yesterday due to this.

Sounds very much like spider mites. Does the rust appear primarily on the apex where new growth appears? In which case you have a problem as they are difficult to eradicate.

First thing to do is to quarantine the affected plants from the rest of the collection. Then have a look on the market for predatory insects or insecticide.

The new growth sans-spines is a strange one, I had a similar problem last year, mostly with Mammillaria. Thankfully all plants have resumed new growth as normal this year. My guess is that it's caused by a virus carried by spider mites, as it seemed to occur at the same time as when I had spider mite problems too.

The echeverias looks like sunburn.... mine did the same thing last year after I put them outside.
This year they have been fine.
I put it down to treating them with neam oil as a spray, I believe it made them susceptible to sunburn.
I had to remove all damage leaves to stop the rotting. and put them in the shade till they recovered

There is a difference between sunburn and sun colour, though possibly they are just degrees of the same. Plants in habitat often display sun colour through being stressed, which is perfectly natural and in many cases the feature that made them more desirable to the original collector than just being boring green.

Sunburn though is where the part of the leaf exposed goes dead, brown and crispy, usually through exposing a plant grown in lower light intensity too quickly to full sun. From the stairs in the picture you look as though you are growing them in the darker interior of the room rather than on a bright windowsill, since Succulents are really high light intensity plants.

I would say your first plant has sunburn, but the second is just sun coloured.

See:-

http://gardeninggonewild.com/?p=17919

FaeLLe wrote:Interestingly this is happening to my Echeveria Agavoides and one Echeveria ....
The tips start turning orange and then the whole leaf turns orange till it dies. Threw out one other plant yesterday due to this.

Your second picture shows plants in a peculiar light. Is this where they reside normally and where/what is it? I get the impression the plants are not receiving natural light. Before making a suggestion about the cause if you could please clarify.


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Looks like the camera white balance set to daylight Brian, but taken under a tungsten bulb? In the old days of film you needed a blue correction filter. Auto white balance in digital cameras usually works these days though, but sometimes you do have to set it manually or correct in post processing. Certainly they do seem to be growing in a room interior, which would make them very sensitive to sun if moved outside.