I purchased some pachanoi the other week, including one not so healthy plant. I saw a small spot of rot on one pot but it was a two plants with five branches in total so I decided to give it a go anyway.
It was badly root bound when I tried to repot it so the roots got quite a beating as I divided it into two plants, I then left it for a week and gave them a dose of anti-rot. Problem is the rot (which is a small spot) seems to have gotten worse. It has not spread, but has deepened in colour (brown) and softened more, now the second plant has developed a small spot.
So how long do you usually leave a plant before giving it a chop? I may have fertilised it too early but it looked like it desperately needed food *sigh* and I have not actually dealt with this disease before. I'm not sure when the panic should set it, the main problem is one which has rot at the tip, which I guess I can cut off

You got to give us a photo, but I think I know what you mean,,,

No panic. Trichocereus are almost unkillable. I told you not to get a named or heavily cloned, as a seed raised plant might be blackrot free, clones are usually infected.

You can't get rid of this thing, learn to live with this. Cutting, stressing, lots of rain/humidity/watering can worsen it, but it always heals, it almost never kills a plant.

It has actually hardened up since I posted this, and some of the colour is improving so I think the anti-rot did it's job, so if you think it won't kill it, then I'll juts give it a monthly dose until it improves, and keep feeding it. It's not got the colour of blackrot, but as I said it seems to be improving. I just think they're really poorly looked after.
I don't think it's a clone, the guy told me he has been growing cuttings from the same plant for 40 years.
I have purchased some small ones down at the nursery, they only had the scop when i went, so I got some polaskia as well, very nice