Orange Staining on Prickly Pear

Trouble shoot problems you are having with your cactus.
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dvdmsy
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Orange Staining on Prickly Pear

Post by dvdmsy »

A couple of plants that spent the winter indoors and dry are suddenly showing a kind of orange rusting. I presume it's a fungus. Any recommendations on what to do about this?
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Nic
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Re: Orange Staining on Prickly Pear

Post by Nic »

If it can't be rubbed of, then it is the plant compensating for not being used to that much light, if not, then I don't know.
There is no cactus you can't eat, but you just might regret it if you eat the wrong one.
dvdmsy
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Re: Orange Staining on Prickly Pear

Post by dvdmsy »

Thanks for your reply, Nic!
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Re: Orange Staining on Prickly Pear

Post by dvdmsy »

I guess the next question is, will it eventually recover its vibrant green color?
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Nic
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Re: Orange Staining on Prickly Pear

Post by Nic »

If what I said was true, it should turn back once it is adjusted to that much light, it should turn green again. Browning/Redding happens a lot with aloes grown in full sun, every year some of my aloes turn when I put them outside, and then by the end of the summer they're greener again.
Sorta like this cholla is a reddish brown, if you put it in less light, it would get lighter
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There is no cactus you can't eat, but you just might regret it if you eat the wrong one.
dvdmsy
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Re: Orange Staining on Prickly Pear

Post by dvdmsy »

I think the reddening here is from light -- you're right about that. But I fear that it might be from too much artificial light over the winter. The plants spent the season in a cool hallway that received sun from a skylight, but at night an overhead light illuminates the hallway. The plants never had any darkness for about three months. This could be the problem.
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Re: Orange Staining on Prickly Pear

Post by esp_imaging »

Standard artficial lighting or room lighting is dark (quite literally thousands of times darker, potentially) compared to sunlight. Unless it was inches from a light source, I doubt if it would be a problem.
It looks to me more like a rust / fungal issue, maybe due to cold/humidity if you have just put them onto a balcony. Most opuntias are pretty resistant to dry cold but far less to damp cold.
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greenknight
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Re: Orange Staining on Prickly Pear

Post by greenknight »

Fungus rust occurs in patches with a definite border, which this lacks. Look more like a response to environmental conditions.
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dvdmsy
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Re: Orange Staining on Prickly Pear

Post by dvdmsy »

What's weird is that only the two plants without glochids are showing this orange-ing. The more prickly plants have no such color change.
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hegar
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Re: Orange Staining on Prickly Pear

Post by hegar »

I also do not have any definite answer as to why your plant developed those reddish streaks. However, I doubt, that a pathogen is the reason for it. Rusts for example are almost unheard of on cacti. They would also rupture the epidermis and very tiny spores would be inside the lesion, which is usually a blister-like structure, or be present on the outside also, once it has ruptured.
I assume, that the tissue of the reddened "pads" is firm, just like that of the healthy looking ones. Insects and mites can most likely also be ruled out.
So that leaves basically only some kind of environmental factors (light, heat, frost, etc.).
Because prickly pear cacti are such vigorous growers, I would sacrifice that cladode and check out, what it looks like on the inside. Is it drying up? Is there a rot developing, a color change, etc.?

Harald
dvdmsy
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Re: Orange Staining on Prickly Pear

Post by dvdmsy »

Thanks, Harald. The plants are fine except for the discoloration. The side of the cladode that was not facing "out" or the artificial light exposed side look fine. It has to be the fluorescent bulb that is the culprit. Three months of that constant shining resulted in a kind of burn. Perhaps not that weird. Lesson learned.
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