Is it a disease???

[leon4]

Hello all!

I started my collection with these 5 babies a few months ago. I recently noticed that something was off with one of them and got me curious.I'm not even sure it's a disease or anything but if you have any experience over the matter it'd be appreciated.
I'm wondering if the slight discoloration(deeper green) in the mid-low part of the plant and the brownish color near the roots is something to worry about.

Thanks in advance.

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[teo]

I think it's just aging. (google 'corking on cactus' for examples)

[greenknight]

Agreed about corking. Also, the diminishing of the blue color on the older growth is not unusual - it's just a waxy coating on the surface, tends to wear off with age.

[leon4]

That's nice to hear. Did some reading and seems that you are right! Thanks a lot guys!