brown/black spots taking over Cereus peruvianus

Trouble shoot problems you are having with your cactus.
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someguy
Posts: 8
Joined: Sat Mar 21, 2015 5:49 pm

brown/black spots taking over Cereus peruvianus

Post by someguy »

Good morning,

I have a Cereus peruvianus (ID'ed thanks to this forum!) that I am getting quite concerned about. For a while (months), there were some black spots on a new arm that started at the end/tip. At first it was just on that arm and only at the tip, and after a while they turned more brown and seemed contained/done. Over the past couple months, it's accelerated a lot, with the entire end of the new arm now appearing "dead" and spots starting on older, bigger arms. It appears to be starting at the top/tip and working down, often starting at the spine clusters. I read the pest guide several times and nothing quite seems to fit. I don't want to guess on a cause and potentially make things worse with an incorrect treatment.

Within the past week or two at most, it seems the Cereus shed a number of what I'm 99% sure are black seeds (as opposed to pests).

Can anyone clue me in as to what's going on and what action I should take? Thank you.
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adetheproducer
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Joined: Tue Sep 03, 2013 4:15 pm
Location: Porth, the Rhondda, Wales

Re: brown/black spots taking over Cereus peruvianus

Post by adetheproducer »

I would consider removing the offending stem. It looks to be something fungal/bacterial and entered the plant via the areloes. Could be a mite infestation but does not look quite right for that. Yes they do look like seed, test them and see if they grow.
And as the walls come down and as I look in your eyes
My fear begins to fade recalling all of the times
I have died and will die.
It's all right.
I dont mind
I dont mind.
I DONT MIND
someguy
Posts: 8
Joined: Sat Mar 21, 2015 5:49 pm

Re: brown/black spots taking over Cereus peruvianus

Post by someguy »

adetheproducer wrote:I would consider removing the offending stem. It looks to be something fungal/bacterial and entered the plant via the areloes. Could be a mite infestation but does not look quite right for that. Yes they do look like seed, test them and see if they grow.
Thanks for the quick reply. I'm a total novice -- I searched the forums and Google but only saw talk of when to cut off a stem or part of it, but not how. Is a sharp knife or kitchen shears (cleaned with rubbing alcohol prior) ok? Does it matter if I cut straight across (level) or angled? Will I need to do anything with the lower part that's still on the plant?
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adetheproducer
Posts: 1576
Joined: Tue Sep 03, 2013 4:15 pm
Location: Porth, the Rhondda, Wales

Re: brown/black spots taking over Cereus peruvianus

Post by adetheproducer »

A sharp knife it best. Yes clean the blade with alcohol and cut at an angle not flat. You might want to keep the stem very much separately from the main plant and put it in a pot of grit. If the black stuff is not life threatening it should set roots and then you will have another one. Plus dont rush to follow my instructions my area of cacti is mainly around miniature tap rooted things. Wait for more advice before doing anything there are far more experienced people on here than me.
And as the walls come down and as I look in your eyes
My fear begins to fade recalling all of the times
I have died and will die.
It's all right.
I dont mind
I dont mind.
I DONT MIND
HP22B
Posts: 238
Joined: Tue Jul 29, 2014 2:43 pm

Re: brown/black spots taking over Cereus peruvianus

Post by HP22B »

Looks like it's turning into ziricote :wink:
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greenknight
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Location: SW Washington State zone 8b

Re: brown/black spots taking over Cereus peruvianus

Post by greenknight »

Yep, surgery is the only answer - cut off the infected part. I would just throw that part away, it's too far gone to grow as a cutting in my opinion. Doesn't look like mite damage, some kind of infection.

For those to be seeds, there would need to be a fruit. The fruits are large and round - these are sometimes referred to as "Peruvian Apple Cactus" .
Spence :mrgreen:
someguy
Posts: 8
Joined: Sat Mar 21, 2015 5:49 pm

Re: brown/black spots taking over Cereus peruvianus

Post by someguy »

Thanks again to everyone's input. I performed surgery a couple days ago and thus far, the patient seems to be doing well.
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