I got this guy about a week ago, and at that time,
the brown dot was tiny. It's spread since then. It doesn't seem softer or rotted, but honestly, it is too small to poke well enough. best free image host
What do you think I should do? I really don't want to resort to surgery. I am hoping it is a shipping bruise, but I don't want to wait too long to find out it isn't.
I am not sure what to think of this. You state, the lesion has become bigger, which could mean, that there is a pathogenic microorganism present.
To me it also looks, like the lesion is sunken. If this is a fungus, you should be able to view either a fuzzy growth on it or little raised dots, which may resemble small spheres or slits. Also, the spot would be softer than the rest of the cactus. You can take the blunt end of a pencil and push lightly against the healthy tissue and then the lesion, in order to find out, if there is a difference in turgor. If that lesion does continue to increase in size, you will need to do some surgery and remove the lesion and some surrounding tissue with a sterile cutting tool and then apply sulfur dust or another disinfectant to the wound surface.
