The picture explains it. I thought sunburn until I saw the photo. It has been very hot but they are shaded by the mimosa mid-day. Soil is not overly damp but maybe a water issue? Fungus? I wonder what AH would surmise?

I'm not certain if that is a fungus, or perhaps scarring from an insect or evidence of some other creature taking bites to eat . Some of my cactus have gotten that as well but it never posed any sort of threat. I think its just some form of blistering cactus naturally experience.

Yeah Im no expert but it was the same for me, cact seem to take care by themselves..

I also fail in knowing truly what this is or how it affects the plants.

However, living in the South East Coast area of the USA, I have indeed also encountered this 'growing' on my cacti.

I will follow this thread along so I may learn with you

The little I can say is that it has not seemed to kill any of the cacti.

Be well Cactus spirit

For the time being i moved them into a more shaded area and letting the soil dry. The main concern is that the growing tips are scarred. This is the same group that i had one turn white and appeared to die. Now a new pup is growing from its' root so i agree they are tough. But you know i treat them like they are part of myself. When i have stressed plants they appear in my dreams if i have spent a lot of time caring for them.. Kinda interesting that i can feel them like that.

For the time being i moved them into a more shaded area and letting the soil dry. The main concern is that the growing tips are scarred. This is the same group that i had one turn white and appeared to die. Now a new pup is growing from its' root so i agree they are tough. But you know i treat them like they are part of myself. When i have stressed plants they appear in my dreams if i have spent a lot of time caring for them.. Kinda interesting that i can feel them like that. Still a cactus newb.

It doesn't look like fungus to me. It looks like general corking, which can happen from just about any thing and doesn't cause any real damage to the plants. It's nearly impossible to keep cacti from getting some little character marks, ime.

Cacti that I've had that got damage on the growth tip just pupped. I've had them pup a basal pup or just push out a new one right on top. Shouldn't be a major problem. It will push through and carry on somewhere. The cacti in the lower right corner of your first pic looks like slugs might be taking bites off it.

And AH would tell you you needed an indoor hydroponic lab setup, cause serious growers don't deal with, like, the sun and rain and stuff.

This is what i thought today as i checked on some of this year's new plantings that are still only .5cm high. Something ate almost all of them!!!!. The only thing left of most was some fuzz that was their little baby thorns I put on my magnifying glasses and dug the survivors out with a teaspoon and transplanted them into a new pot with new soil and moved them back inside. maybe 10 out of 38 were there and some had huge chunks missing. It will be interesting if they recover to see what shapes they take.

I am thinking I need to put out some diy slug traps aka cheap beer in a tupperware...

I had the same problem except it was a caterpillar invasion, they liked to munch the top. The seedlings where tiny (about 5mm), lots of them died but most of them survived and now they look like this :


This one has been attacked 2 times so it's a pup on a pup



Good luck with your babies and don't worry too much, they are stubborn.