I just purchased a cactus and I'm trying to learn more about them. After I made the purchase I noticed something strange (see pic). I just spent an hour online trying to figure this out but I still have no idea. Is this a disease? If so is there anything I can do about it? Also can you help me identify the plant? Thanks.
i'm not too good yet with cacti id's...so, someone else will have to chime in on that :) as for the base, the bottommost section could just be the normal 'corking' that occurs on older plants. it could also be some kind of fungal infection. the black spot could be fungal or bacterial and would likely be the result of damage (plant fell over or was knocked in to with something sharp). could even be a sunburn or inscect damage. sorry i'm not more definitive...at the least you have a few avenues to investigate while waiting for other input.
Appears to be Echinocactus grusonii ??? not 100% sure... bright light and water only when bone dry, and no standing water in the drip tray. By keeping the Cactus on the dry side, there will be less opportunity for fungus to attack the barrel.
It is a Parodia, group Notocactus (or Eriocactus if you like). Search for Notocactus claviceps for example, and you will find plants similar to yours. The discoloured parts are probably not dangerous (and if it is there is almost nothing you can do about it). I have seen similar damages on plants from this genus, and as long as they do not spread they do not seem to do any harm. Just check that they are not caused by scale insects, if so you must eradicate them, of course. It likes more water than an Echinocactus grusonii (but not standing water, as K Baron wrote).
