Blue Torch turning purple!

Trouble shoot problems you are having with your cactus.
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Virginia
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Joined: Sun Sep 27, 2020 10:22 am
Location: Las Palmas de Gran Canaria, Spain

Blue Torch turning purple!

Post by Virginia »

Hi everyone,

I've been growing what I believe is is a Pilosocereus azures (Blue Torch) during two years and it looks pretty healthy, nearly a meter height and with 3 smaller sprouts growing from its base -- except that over the past 2/3 weeks it has developed this weird purple like colour at its very top.

I'd think it's just a nice pigmentation development if it wasn't because it looks kind of rugged and hollow (again, just at the top, coinciding with the coloured area). I've attached some pictures. Has any of you experience with this kind of cactus? Any idea as to what could it be?

Thanks everyone - let me know if more info is needed.
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greenknight
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Location: SW Washington State zone 8b

Re: Blue Torch turning purple!

Post by greenknight »

I'm pretty sure the discolored part is dead. I think you need to cut it off well clear of the discoloration.
Last edited by greenknight on Mon Sep 06, 2021 6:35 am, edited 1 time in total.
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anttisepp
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Re: Blue Torch turning purple!

Post by anttisepp »

Cut it off as soon as possible before this infection will spread and kill all your plant.
Heal wound with hydrogen peroxide 3% and then sulfur powder.
Don't worry very much, it will regrow nice new top again.
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greenknight
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Re: Blue Torch turning purple!

Post by greenknight »

Right - do it quick before it spreads any farther.
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Virginia
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Re: Blue Torch turning purple!

Post by Virginia »

Oh wow - I wasn't expecting it'd be so bad! Thanks SO MUCH everyone for your help. I'll cut the top off and hope it won't die!

One more thing before I do: should I put the cactus in the shade while it's healing?

Thanks again to you three - I very much appreciate your time and help.

Virginia
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Steve Johnson
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Location: Los Angeles, CA (Zone 10b)

Re: Blue Torch turning purple!

Post by Steve Johnson »

Virginia wrote: Sun Sep 05, 2021 5:21 pmOne more thing before I do: should I put the cactus in the shade while it's healing?
Absolutely. By the way, make the cut at an angle, not horizontally. A flat top invites mold and fungal infection if water pools up in the middle as the exposed tissue tries to form a callus, so an angled cut avoids the problem.

I think a fungal infection is what led you to this point:

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From the Fungus section in the CactiGuide Pests and Diseases page, here's an example of what it looks like on an Echinocereus:

fungus_echinocereus.jpg
fungus_echinocereus.jpg (82.54 KiB) Viewed 1337 times
If you just want photos without all the blather, please visit my Flickr gallery.
My location: Los Angeles, CA (Zone 10b)
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Virginia
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Re: Blue Torch turning purple!

Post by Virginia »

Super, thanks for the indications. I've now cut the top and, on inspection, indeed, the purple area was rotten, blackened, inside.
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Steve Johnson
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Re: Blue Torch turning purple!

Post by Steve Johnson »

Virginia wrote: Sun Sep 05, 2021 8:12 pmI've now cut the top and, on inspection, indeed, the purple area was rotten, blackened, inside.
Good -- just make sure that you cut all the way down until you see nothing but green tissue. Hopefully you've already done this, but in case you didn't...

Sterilize the knife with alcohol before you cut, and do it each time you cut. When you're done, cover the exposed surface with a liberal dusting of sulfur powder (anttisepp's recommendation to treat it with 3% Hydrogen peroxide first is a good idea). When it dries, any excess powder will simply blow away. Because you live in a desert tropical climate, I believe you enjoy year-round growing for cacti (in other words, no winter dormancy as we experience north of the tropics). If I'm right about that, you'll be in a good position to see a new stem or two growing out of the cut sooner rather than later.

Best of luck!
If you just want photos without all the blather, please visit my Flickr gallery.
My location: Los Angeles, CA (Zone 10b)
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Virginia
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Re: Blue Torch turning purple!

Post by Virginia »

That's correct - there's not such a thing as 'proper' winter here - temperatures always ranging between 20 and 26. That's great to hear the top might grow back again soon :)

Yes, I cleaned the knife with alcohol before and after (lesson learnt from a previous mistake).

Thanks again for your help Steve! Much appreciated! All the best to you and your cacti :)

Virginia
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Steve Johnson
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Re: Blue Torch turning purple!

Post by Steve Johnson »

You're welcome, Virginia!

By the way -- when the Blue Torch starts growing a new head on the cut, please share a progress photo with us here.
If you just want photos without all the blather, please visit my Flickr gallery.
My location: Los Angeles, CA (Zone 10b)
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Virginia
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Re: Blue Torch turning purple!

Post by Virginia »

Will surely do! Let's see how long it takes...

Cheers, Virginia
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