Ill cactus

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CactusBob
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Ill cactus

Post by CactusBob »

Hello,

I'm new here and looking for a bit of help with my ill cactus. It's gone a bit yellow, with white fungus and it seems to be sort of collapsing in on itself! Any ideas what might be wrong? Is it salvageable?

Thanks!
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DaveW
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Re: Ill cactus

Post by DaveW »

Afraid it looks as if it's gone rotten. Take it out of it's pot and see.
CactusBob
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Re: Ill cactus

Post by CactusBob »

It disintegrated into mush as soon as I touched it! I don't feel like over watered it but maybe I did. Does this type of cactus need less water than others? Actually in this pot it didn't have drainage holes so I drilled some in... but maybe not enough.
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greenknight
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Re: Ill cactus

Post by greenknight »

What kind of potting mix was it in? If it retains too much water, that makes it very hard to avoid over-watering.
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CactusBob
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Re: Ill cactus

Post by CactusBob »

It was some specialised cactus and succulent mix that I got. It never grew as the others did that I bought at the same time so maybe it was already starting to go when I bought it (April last year).
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greenknight
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Re: Ill cactus

Post by greenknight »

That's possible. While most of what's sold as cactus and succulent mix isn't very good (see - http://www.cactiguide.com/article/?article=article8.php ), seems there was a particular problem with this one. Not sure what species it was, but unless you go to a specialist grower you aren't likely to get any cacti that are that fussy.

Also, you should clean all the old mix off the roots when changing to a different mix - http://www.cactiguide.com/forum/viewtop ... =25&t=9222

Everyone who grows cacti has probably has probably had losses from rot, sometimes you can't ever figure out why it happened.
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CactusBob
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Re: Ill cactus

Post by CactusBob »

Ah, I didn't clean the old mix off so maybe that was a problem. When I threw this one away I noticed that the root ball was tiny and had hardly developed at all - certainly not into the new mix I had used when I repotted.
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greenknight
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Re: Ill cactus

Post by greenknight »

I made the same mistake for years. I often got away with it, because I always freed up some of the roots and got them into the new mix, but I'm sure I would have has better growth and fewer losses if I had bare-rooted them completely.
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Aiko
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Re: Ill cactus

Post by Aiko »

Looks like a Melocactus. It likes to be warm, also in winter. Above 10C at minimum (occasionally it should not mind a colder temperature, but basically it should like it warm).
CactusBob
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Re: Ill cactus

Post by CactusBob »

If your identification is right then that could be the problem. I've also seen the below written:

"Melocactus are somewhat finicky cacti with unusual requirements. They shouldn't be allowed to completely dry out, even in winter"

I had only watered it once since September/October so maybe a combination of bad repotting practice plus lack of water and warmth killed it off.
jfabiao
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Re: Ill cactus

Post by jfabiao »

If you put a cactus bought at a garden center or supermarket straight into a new pot with fresh compost around it but without breaking the peat ball it comes in, the roots will be enclosed in an impervious container, as it is very hard to re-wet dried peat (some peat is treated with wetting agents, some doesn't). Whenever you water, the water will flow freely through the fresh compost without entering that compact peat block and the plant will slowly wither. Better to break off most of the roots and treat the plant as a cutting if you can't free them from all the peat it comes in.
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greenknight
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Re: Ill cactus

Post by greenknight »

Yes, it's a very unhealthy situation. At the same time, the soil in the bottom of the pot may remain saturated too long and go sour, since the plant is unable to take up much of the water. Any root that does manage to poke out into that is likely to rot. Thus you can get the paradoxical result that one plant will wither from lack of water, while another develops root rot from soggy soil, when both got the same treatment.

The way it's so completely rotted now makes me suspect it had already begun before fall. Chilling would accelerate its decline. but I wouldn't expect it to get that bad that fast unless it got actually frozen. I thought it might be a Melo (though not sure, as I said) but root problems struck me as the most likely cause of death.
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CactusBob
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Re: Ill cactus

Post by CactusBob »

Thanks for the help.

Is it only necessary to de-soil the roots on shop/garden centre bought plants? Or any plants where you will be potentially using a different mix than the plant has had previously?
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Steve Johnson
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Re: Ill cactus

Post by Steve Johnson »

CactusBob wrote:Is it only necessary to de-soil the roots on shop/garden centre bought plants? Or any plants where you will be potentially using a different mix than the plant has had previously?
In both situations, always clean the roots thoroughly before you repot. If you don't, any remnants of old mix hiding up in the root ball could be holding enough moisture between waterings to set up the conditions for rot. I lost a few cacti that way -- hard lesson, so hopefully this'll help you avoid repeating the same mistake. I also highly recommend soaking the roots in 1% Hydrogen peroxide for 15 minutes, then rinse them in running water and let them dry out before repotting. The peroxide kills any potential rot-inducing pathogens, and it may promote faster healing of the roots. I've been making this part of my root prep routine since 2012 -- while I don't have any solid evidence to back it up, the peroxide treatment seems to work well. This photo shows the setup when I did for the first time on 9/30/12:

Image

Truth be told, I wasn't cleaning the roots of my cacti as throughly as I should've back then, so the foaming came from organic materials in the old mix. I pay much more attention to root cleaning these days, and if you do the same, foaming action should be minimal.
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greenknight
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Re: Ill cactus

Post by greenknight »

I don't usually go to that much trouble, but yes, you should remove the old mix completely anytime you change to a different mix. Water doesn't readily move between media with different pore sizes - if there's a boundary between media of different textures and you add water in one side of that boundary, the water won't soak across to the other side until it's completely saturated on the first side. If you leave a pocket of the old mix around the roots, you might not have any problems if the two mixes are similar enough. If they're too different, though, there could be trouble - the old mix might stay too wet, like Steve said, or it might not take up any water at all. Neither of these is good for the cactus, obviously.

The peroxide treatment I would recommend for rare, finicky cacti, or when there's reason to believe there's contamination with rot organisms. Common cactus species tend to be very tough plants, though, if you don't want to bother you won't see much difference most of the time - though it certainly wouldn't hurt.
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