Rotting

[Maxy24]

My Cereus peruvianus monstrose is starting to rot. One of it's smaller offshoots, down by the base, is all mushy. The rest of it is fine, but should I unpot the cactus and cut off the rot? Will the rot spread if I don't do something? I'm guessing my potting substrate is not appropriate for it, I had a very hard time finding pumice or grit so tried improvising with small stones and it didn't work out. But I was planning on not watering it anymore until spring so I don't think the substrate will matter much until then. I just want to know what to do about the rot it has now.

[sundanz]

Here's what I would do with my limited knowledge. Rot spreads unless you cut it out. So, take it out of the pot, remove all traces of rot and repot the plant. I don't use pumice because I can't find it. I use a 50/50 mix of cactus soil mix and perlite, with more emphasis on the perlite. My plants are growing without any problems in this mix, and yes, they are growing, not just sitting in the soil. I water carefully and since all of my plants are in claypots they dry out quickly. No one ever sits in wet soil for very long, hence the chance of them rotting is slim unless I overwater (which I don't). Hope this helps.

Karin

[Steve Johnson]

Yes, rot absolutely does spread, and the longer it goes, the worse it'll get. First, you'll need to unpot your Cereus and take a good look at the roots. If they're fine, Karin has the prescription right, and once you've cut out the rot you can repot the plant in a free-draining potting mix. However, if you're currently using a heavy soil-based mix and it's still retaining moisture, I'd get the plant into fresh, dry mix right away. The Cereus should be good to go for watering in the spring.

If the roots are a nasty, smelly, gooey mess, you have a somewhat bigger problem. You'll have to cut the stem above the roots and keep cutting until you see only healthy green plant tissue. You'll also need to use a sterilized sharp knife. Isopropyl alcohol is perfect for sterilizing, although you'll need to do it every time you make a cut. Then dust the cut with fungicidal powder (sulfur powder is great) and let it callous in a dry place away from direct sunlight for a month or so. I believe Cereus peruvianus grows new roots rather easily, so I think you'll see them appearing in the spring. Once again, keep the cutting in fresh, dry potting mix after it's properly calloused and don't water until you see new roots.

Perlite can be a big pain in the backside because it floats away, although if Karin uses top dressing on her plants, that would answer my objection. Other good options are Turface and NAPA 8822 (Floor-Dri). I have no problem getting pumice, so there's no reason for me to go with anything else. But if you can't find it, I'd recommend using any of these options to prevent the difficulty you've been going through.

Hope this helps!

[sundanz]

yes, Steve, I use top dressing (gravel) in all my pots,hence no floating perlite!

[Maxy24]

Would home depot sell this stuff ( Turface and NAPA 8822)? Does it come in small bags or only large ones? I'm at college so I don't really know where anything is...we pretty much shop at Walmart. I just know there's a Home depot.

ETA: We also have a Petsmart...would aquarium gravel work? Or does it have to be absorbent?

[sundanz]

I don't know if Home depot sells Turface or NAPA 8822. However, they sell cactus soil and perlite. I use a bag of pea gravel for top dressing but aquarium gravel is just as good. It does not have to be absorbent, it's mainly for decoration anyway. It makes my cacti look better in a natural setting.

[hoteidoc]

Home Depot doesn't sell Turface or NAPA 8822. NAPA Auto Parts carries the 8822 (or can get it for you); AutoZone has an equivalent -- it's all diatomaceous earth. It's @$9/25# bag. Turface you should be able to get @ lumberyard or hardware stores. Price @ the same, but bag is bigger. Aquarium gravels works & more expensive, but if you only have a few plants, (supposed to, personally haven't used) works well.

[Peterthecactusguy]

if you go to walmart go to the automotive section and get the oildry stuff.. It's made by Marathon... It should have 100% Diatomaceous Earth.

[sundanz]

I bought a bag (25 pound for $4.22) of the oil/dry stuff at Walmart yesterday just to try it out. Should I use a 50/50 mix with my cactus soil like I do with the perlite? Why would the oil/dry stuff be better than Perlite?

Karin

[juliab]

sundanz
you sound like me I am so afraid I am going to hurt it more than save it. I have the same problem mine is the white top one got heavy broke off and the bottom rotted just wham this happened and what I did not relies it was top heavy so it had a dry stem so my beautiful top had a stem that was dry no rotting weird huh? so I just stuck it down in the same pot after I took out the rotted stem and added more cacti and a bit of gravel (small ) and re-potted the top it had roots on one side so far so good I thought well I will try its going to kick the bucket if I dont try something. so far its just sitting pretty. I am not goring to water till summer ad I have it sitting where it was so time will tell. I had on gloves and the latex really put some spots on my hands. Or cactus become our friends when were alone and when they get sick or dieing we dont want this to happen its like saying by to a old friend.


Good luck keep us up to date.

[sundanz]

Juliab, thank you. I'm new to cacti, since May, and I'm trying to learn everything I can so my plants will be happy, and stay happy. Maybe I go overboard sometimes, but that's the way I am, I want to do it right. Winter is coming soon and I already bought a little greenhouse where they are now living.

As far as your plant goes, the one that broke off, well, you did the right thing. It should get new roots, cacti are actually pretty tough plants. Whenever I buy a new plant I take it out of the pot it came in and repot it in a clay pot. I remove all the soil from the plant before repotting, inspect the roots for bugs etc and if everything is well it goes in the new pot.You could never do that with a "regular"plant, they would surely die.
Growing cacti is an addiction as you may well know. I was just going to hsve 1 or 2, now I'm up to 70 and I'm already thinking about adding another greenhouse!

It's crazy!

Karin

[fanaticactus]

I bought a bag (25 pound for $4.22) of the oil/dry stuff at Walmart yesterday just to try it out. Should I use a 50/50 mix with my cactus soil like I do with the perlite? Why would the oil/dry stuff be better than Perlite?

Karin

Unless you hear differently from someone else, Karin, I would use a 50/50 mix potting soil/Oil-Dry. You could probably even go as much as 80/20 in favor of Oil-Dry. I use it in my mix and think it's great. It's better than perlite in my opinion because it's not light enough to float like perlite and it's more porous and holds more water, but not enough to make to substrate soggy. It seems to give cacti just the right amount of moisture. I've kind of given up on perlite because one of the last bags I bought had so much crushed perlite (about a quarter of the bag it was nothing but white dust, which blew all over the place when I added it to the soil. I was afraid I'd breathe it in.

[Maxy24]

So I unpotted the cactus and have a bit of a dilemma. I found the problem, most of my potting mix is marble stones but around the roots themselves it was mostly soil and this soil was still moist, and it's been a month since it got watered. I'm not sure if this soil is stuff I failed to remove when I took it our of it's old pot (which was mainly soil) or if it's actually soil from my mix. In any case that's what caused the rot.

My issue is I'm not sure what's rotted and what's not. The two little offshoots that were obviously rotted came off, but by this time they were dried up, crunchy things. The "skin" of the cactus around where these offshoots were is all dry and brown and peeled off a bit when I removed the dead offshoots. Underneath the skin the area is brown. It has a little give when I push on it but is not squishy, so I'm not sure if it's healthy or dead/rotted. If it is rotted I'm afraid I must cut off the stem.

I am also struggling to get the dirt off of the roots and I can't tell if some of the roots are rotted or not because they are caked in dirt. Some of them also feel like they have some sort of papery layer over them, like it was planted in one of those disposable peat pots and when they took it out some of the peat pot stuck to the roots. I really want to rinse the dirt off of the roots but know the cactus might not appreciate that.


I took some pictures of the stem where I removed the rotted offshoots to show you what I'm talking about. These are the two spots where the skin is peeled off and the tissue underneath is brown, but not squishy.






What would you do with this plant?

[hoteidoc]

You could cut, callous, & reroot. But since everything above that is healthy, I'd probably rock around the defect & let it carry on until something more serious shows. Then it's back to Plan B.