Can a San Pedro Cactus cutting go bad?

Meaning it's consumption would result in getting sick? Or a loss of potency? How long would this take if left in a cool, dark spot? A cutting SWIM has is getting these black growth-like bumps on it. Though the bumps are hard and clearly not mold.

 

it could be rot, if that is what you think that it is you should probably cut it off before it spreads.

 

I would cut it off as well, although almost every time i've done San Pedro it's had a more tannish 'dead' spot on it. Those spots usually go inwards though, they don't protrude out.

The core is the main thing that will make you sick and the alkaloids vary tremendously between cacti so don't freak if it's not potent or you puke.