Ferocactus latispinus issue

[samreu]

I was hoping someone could give me some thoughts as to what may be afflicting my ferocactus - the stem has got a mustard colored scaling to it in several spots.
Was a healthy specimen last year - last watering was mid-October before I wintered it in a north facing window with 5-6 other cacti I have overwintered in this same windowsill - north facing and I have a blind that is about 1 foot from the window which I close to keep the cooler temps in there, although I do leave the blind open enough for air movement - I monitor the temps high/low with a digital and it hovered between 55-65F for the november to mid-march period - took it out a couple of weeks ago - no issues with any of the other cacti that I can see.

[samreu]

Any thoughts anyone?
Or do i just put it in quarantine and see what its fate will be with time?

[hegar]

To me this looks like a cultural issue. If the discoloration is only present on one side, it could have been caused by either sunburn or perhaps a cold injury. It does not seem to be a rot or another pathogen. It would have helped, if you could have shown the whole plant, including what it looks like on the other side of the affected ribs.

Harald

[Steve-0]

Glad to hear a more learned comment which helps educate a newbie, me. My thought was cold temp damage but samreu describes careful monitoring with Temps. My large echinocactus grusonii got a surprise frost burn, my fault, and it looked like this.

[anttisepp]

Cold injury is typical to latispinus vs other ferocacti.

[samreu]

Thanks for the comments. Harald, the rest of the plant looks not bad, in my 2nd pic you can see another rib to the left of the worst part also affected. I looked closer and there are some faint hints of discoloration elsewhere, ever so slight. If Harald and anttisep are correct about the cold theory, i suspect it must have been cold drafts that were the issue and if so, seems the latispinus is pretty sensitive. The hi-lo save function on the digital thermometer never showed anything lower than 55F?? I had o trolli, mamm celsiana and pringlei, echinopsis subdenudatum, gym horsti, monvillei and bruchii in same window sill with no issues. Hopefully the issue won't start further complications, guess time will tell.
Thanks for your input.