Cactus cutting gone bad?

[Chindit]

I haven't done the surgery yet, but I am kind of resigned to this not turning out well.
At some point, I would need some step by step pointers for planting the offsets . Not sure this is the right thread for that issue.
(I have planted offsets or cuttings in the past with mixed success, so I obviously would want to do this correctly).

[Steve Johnson]

I haven't done the surgery yet, but I am kind of resigned to this not turning out well.
At some point, I would need some step by step pointers for planting the offsets . Not sure this is the right thread for that issue.
(I have planted offsets or cuttings in the past with mixed success, so I obviously would want to do this correctly).

Believe it or not, CactiGuide does have a forum that deals specifically with cuttings and offsets:

https://www.cactiguide.com/forum/viewforum.php?f=21

After you remove your offsets from the parent plant, start a thread there with photos of each offset top-to-bottom so we can see them in their entirety. Also, please be sure to give us their lengths -- that'll be important for determining the correct sizes of the pots you'll need for rooting. My experience with rooting offsets is limited, but if none of our other members chime in right away, I'll be there to guide you further. Knowing the species of your cactus would be helpful. I grow only 65 species and unfortunately yours isn't one of them, so when you start the thread in the Cuttings & Offsets forum, ask for an ID. Hopefully a member who responds will be able to give us the species name plus an idea about how long it'll take to root.

[Chindit]

Sorry for the delay, but here are a couple of photos of the root after I cut it. I certainly have no idea what I am looking at.
Also, on the plant itself, I saw that where I cut off the dark areas (and used sulfur powder this time), the same dark/blackened areas have now reappeared so it looks identical to the oringinal two photos I posted a couple of weeks back.
Thanks for any advice on how to proceed.

UNADJUSTEDNONRAW_thumb_1b4.jpg (52.93 KiB) Viewed 1817 times

UNADJUSTEDNONRAW_thumb_1b5.jpg (49.36 KiB) Viewed 1817 times

[Steve Johnson]

Based on those photos, I definitely suspect nematodes, although I can't say for sure. MikeInOz is a professional horticulturalist with many years of experience, so I'll send him a PM and ask him to review everything in this thread. If he confirms my diagnosis, you'll see it here. If he doesn't, he should be able to tell us about what's going on with the nodule you sectioned. Either way, the situation doesn't sound good, and removing the 2 offsets you can root will at least give you the ability to save what's left of the plant.

By the way, know your enemy -- if you do have a root knot nematode infestation, here's what the nematodes look like under a scanning electron microscope:

C0093426-Root_Knot_Nematode_SEM_.jpg (173.96 KiB) Viewed 1783 times

[Chindit]

Thanks Steve.
Any thoughts on why the most recent cuts I made--using the sulfur powder--still led to the blackenng of the cut area?

BTW, that is one strange, pre-historic looking creature.

[MikeInOz]

You might be able to remove it with your bare hand. If not, sterilize a sharp knife with alcohol and do the cut right on the attachment point indicated by the red line.

Steve, It would be much better to take the cutting here. Cutting into old parts is much more slow to root and the resulting roots are often weak. This goes for all cacti and succulents.

cactus cutting.JPG (52.18 KiB) Viewed 1769 times

[Steve Johnson]

Mike confirmed my nematode diagnosis, but the situation is worse than I thought. This is one of your photos (left) and the same photo I enhanced using the auto level filter in Photoshop (right):

02.jpg (45.96 KiB) Viewed 1742 times

While the nematodes were doing their nasty business in the roots, the stems were being eaten from the top down due to fungal infections enabled by the nematode infestation. I thought you might be able to take the cutting on the right, but the enhanced photo says otherwise -- the red circles show that 4 of the stems' growth points are gone. The only part of the plant you might be able to save is the offset that still has a growth point.

Ideally offsets and cuttings should be taken in summer, but I don't think you can wait that long. Best recommendation right now is to have you remove the offset in April or May. If the main stem's fungal infection gets dangerously close to the offset, remove it immediately. Give me its length, and from there I can determine the right size of the pot you'll use for rooting along with further instructions.

[Chindit]

Thanks Mike and Steve for that information. It all makes sense to me now. (although one question would be why it took the nematodes so many years (8,10?) to have this effect).
Steve, I may have misunderstood your previous message re the offsets since I removed them last week (although the infection did look like it was getting close to the offset). One good thing is that there were two smaller offsets, about 3 1/2 inches long, not visible from my original photos (hopefully that is not too small). The offset pictured above is about 9 1/2 inches long.
Thanks,
Joe

[Steve Johnson]

Thanks Mike and Steve for that information. It all makes sense to me now. (although one question would be why it took the nematodes so many years (8,10?) to have this effect).

The answer is this -- you have a really big cactus, and if it was a substantially smaller plant, it would've died years ago.

One good thing is that there were two smaller offsets, about 3 1/2 inches long, not visible from my original photos (hopefully that is not too small). The offset pictured above is about 9 1/2 inches long.

The 3 1/2" long offsets are definitely not too small, and all 3 offsets can go into the same pot for rooting. Unfortunately I don't have enough time to give you detailed instructions today, but I will tomorrow. In the meantime, you gave me the offsets' lengths, so please measure their diameters at the thickest part and let me know what they are.

[Chindit]

Steve, the 9 1/2 inch offset, as well as one of the smaller offsets has a diameter of 3/4 of an inch.
The other 3 1/2 inch offset has a diameter of 1/2 an inch.
Joe

[Steve Johnson]

Steve, the 9 1/2 inch offset, as well as one of the smaller offsets has a diameter of 3/4 of an inch.
The other 3 1/2 inch offset has a diameter of 1/2 an inch.

A 5" x 5" pot should be good as your "rooting pot", but this will be strictly for rooting the offsets. Once they develop strong roots, they'll need their own smaller pots. This requires patience, so let them start growing roots over the course of spring and summer, then figure on spring 2025 as the time when they'll be ready for regular deep watering and fertilizing as they grow in the correctly-sized pots that'll accommodate their new root systems.

For your "rooting pot", you'll have a layer of potting sand with a layer of substrate below it. The layer of substrate I had in mind is a 60% pumice-40% soil mix. However, your cactus appears to be a Cereus peruvianus, and based on what Mike said to me in a PM, the substrate needs to be a little richer since Cereus species are hungry plants. I sent him another PM inquiring about what'll be the most suitable -- as soon as I hear back from him, we can proceed.

[Steve Johnson]

And we're ready, Joe.

You'll need the following:

• A clean 5" x 5" pot. Nonporous pots are best, although I don't think it matters if you use a porous clay (AKA terracotta) pot as your rooting pot.

• From Amazon, potting sand...
  
  https://www.amazon.com/Original-Ingredi ... r=8-3&th=1
  
  ...Rosy Soil Cactus and Succulent Potting Soil Mix for Houseplants...
  
  https://www.amazon.com/Rosy-Soil-Cactus ... hdGY&psc=1
  
  ...horticultural pumice...
  
  https://www.amazon.com/Horticultural-Pu ... hdGY&psc=1
  
  ...and plant stakes:
  
  https://www.amazon.com/Support-Adjustab ... 0aWM&psc=1

• You'll need something to keep soil from coming down out of the pot's drain hole. A piece of fiberglass window screen works, although you can find something similar at your local nursery.

An artist I definitely am not, but hopefully the following photos will be good visual aids for you...

Rooting_pot01.jpg (37.64 KiB) Viewed 1609 times

Make a mix of 50% Rosy Soil and 50% pumice. As you see, you'll have a 2" layer of potting sand above a 3" layer of Rosy Soil-pumice substrate. Dig the offsets down about an inch into the potting sand. The plant stakes will keep them upright -- important since they won't stand up on their own over time. This view from above indicates how you should space them:

Rooting_pot02.jpg (24.31 KiB) Viewed 1609 times

Buy a watering spray bottle if you don't already have one -- easily available at your local nursery or grocery store. The bottle will have 2 settings, mist and stream. Set it to mist. Starting in April, mist the stems once every 3-4 weeks (believe it or not, this helps in the rooting process). Don't worry if the potting sand gets a little bit moist, but don't let it get saturated either. Be prepared for the fact that the offsets will get shriveled over the course of spring and summer -- once again, don't worry as they'll do their growing below-ground first before they start growing above-ground in 2025. When you get into summer (either July or August) gently (and I mean gently) pull up on the offsets. If you feel like they want to come right out, they haven't rooted yet. But if you get a little bit of resistance, that means you have new roots. Should that be the case, you can mist the potting sand to moisten it more than you did before the offsets started putting out new roots. Let the potting sand dry out completely between mistings, and don't mist at all in fall and winter. If all goes well, the offsets will be ready for their own pots in spring 2025. Good news there, the 50% Rosy Soil-50% pumice mix should be perfect for them.

[Chindit]

Wow! Thanks a ton Steve for those incredibly detailed instructions!
I can see now how I had been making mistakes in the past (there really is a lot of mis-information out there).
I feel very optimistic that the "progeny" of this 30 year old plant will live on.
Thanks again,
Joe

[Steve Johnson]

Wow! Thanks a ton Steve for those incredibly detailed instructions!
I can see now how I had been making mistakes in the past (there really is a lot of mis-information out there).
I feel very optimistic that the "progeny" of this 30 year old plant will live on.
Thanks again,
Joe

Always a pleasure! When you place the offsets in the rooting pot, post a photo so I can see what it looks like with the plant stakes and all.

[Chindit]

All items have been ordered. I do have some additional questions though:
-I had put sulfur on 2 of the offsets where the cuts were made. Can they just be placed in the pot wihout removing the sulfur powder?
-Once in the pot, should they be kept out of direct sunlight?
-Is there any danger of the fungal infection that was on the original parent plant spreading to other plants in the house?
Thanks!