Mysterious browning on cacti and other plants

[absolute0]

Yesterday I noticed some tubercles of my Obregonia denegrii turned brown. The affected tubercles are still firm to the touch and are not mushy at all

https://imgur.com/a/xCdHA

I've also noticed a similar browning in my Euphorbia pseudoglobosa (this occurred weeks before)
https://imgur.com/a/dCTQK

And I'm not sure if it's the same condition, but the leaf edges of my Callisia navicularis also turned brown and look as if they've been nibbled on by tiny creatures

https://imgur.com/a/Hwk1Z

Could these be due to spider mites? I haven't noticed any fine webbing though. Or fungal infection? I hope not...

[stefan m.]

Could be sunburn, but think the euphorbia and obregonia are suffering from rot.

[ElieEstephane]

I have the same problem you are having on the obregonia on some aloe nobilis. The "dry rot" can start from any side of the leaves. Still haven't figured out a solution other than ripping off the leaf

[absolute0]

Oh no. A lot of sources say dry rot cannot be cured with one source saying, "Remove and destroy diseased specimens". I can easily cut-off the affected euphorbia segments but I don't know what to do with the obregonia.

Another source says the fungus that causes dry rot is usually short acting and that improving weather conditions can deactivate the disease. Unfortunately, t's been stormy the past weeks here and although these plants don't get wet in the rain, the cold and humidity might be a factor or something.

[stefan m.]

Try to cut off infected tissue as best as you can. Disinfect with alcohol and powder( cinnamon or sulfur ).

[absolute0]

I removed the affected stems of the Euphorbia already but I just left the Obregonia as it is since removing the affected tubercles would be difficult. Weather has improved so I hope it would indeed deactivate the fungi

[7george]

Give your plants more sun and less water. Might me nutrient-deficiency as well. When one my Obregonia had some spots years ago I lost it next winter: these suffer from fungi.

[absolute0]

Give your plants more sun and less water. Might me nutrient-deficiency as well. When one my Obregonia had some spots years ago I lost it next winter: these suffer from fungi.

It does get lots of sun it's just that the weather has been stormy the past couple of weeks but it's all sunny now. Thanks! For one I'll observe and stop watering it for a while.