Sad day...

Greetings folks!

Bit of a downer of a post.
Was checking on my cacti and noticed a few had turned a very funny colour, pulled one out of the pot to check its roots and the whole thing was rotten right up the core, not even enough to try and save.
All up I have lost 3 thelocactus and also an Astro.

Guess I was a little too heavy handed with the watering.
So far the rest seem ok, but I will scaling back my watering routine majorly!

I was surprised these ones kicked the bucket because they were planted in the driest mix I use, at most there is maybe 5% organic matter, the rest is pumice, scoria and a small amount of sand.

Ah well live and learn I guess.

Gee that's terrible news walker. Any indication as to why? Was the soil sodden wet when you up rooted them or any evidence of fungus or mealy?

I honestly have no idea. The roots were bone dry as was the soil.
The inside of the Cactus was just mush, the center was brown with a bit of an orange tinge, no evidence of bugs or anything like that.
The rest of the cacti are fine, growing like crazy and flowering too. I thought if anything would be affected by over watering it would be the Mexicans but they are all fine and pushing out new spines every few days.

Almost sounds like a bacterial infection to me. Don't get to discouraged though some cacti are just weak and give up the ghost with no warning. I recently lost an Escobaria and my only aztekium to something very similar.

Yeah that would make sense. What stumped me was the roots were all completely fine, dry as a bone and appeared healthy, whatever killed them looks like it's taken hold internally and begun eating its way out!
Truth be told they were far from my favourites so I'm not shattered but still not happy they kicked the bucket.
The photo you posted of your aztekium is very similar to how mine looked. Mine went very very pale and yellow. That's what alerted me to the problem.

I always find this part of the season is worst for losses...some plants just aren't ready, whilst others are screaming for a drink. Especially tricky here in Melb...

I agree Navajoa,
Now I am really hesitant to water the others even though they are growing at an amazing rate. A lot have really surprised me. I knew they would come to life in spring but the transformation in the past few weeks has well and truly surpassed my expectations.
There is one thing I noticed about the ones that carked it, they all had flat bottoms (except the Astro) and minimal roots, I'm starting to think that when they got watered the bottom of the cacti has absorbed water which would explain why the roots were fine but the top was a ball of mush.
I'm in a catch 22, do I restrict watering and possibly affect the growth rate of those that are growing well or continue watering as I have been and run the risk?
At this point I am leaning more towards running the risk.