Evil Genius

Second plant has scale too. Same treatment, Neem, Azamax, Spinosad etc.

The original plant suffers from scale, which then again causes substantial scarring. Look into pesticides against Scale, e.g. Azamax or something similar.

Hey mate, not sure what flower it is but it definitely isn't a Trichocereus flower. The whole flower development cycle on Trichocereus is totally different to that of the plants who have these flowers. It might be an aborted flower bud from a very early stage, but with how this looks it is honestly highly unlikely. It seems to sit on the areoles, but not in a natural way that flowers emerge from Trichocereus areoles. I am really sceptical of this, and I think it might've got stuck there by accident. But yeah, if this plant should flower at one point you know for sure. Do you have other pics of this clone? There are some cacti that flower like this, but they are other genera and this looks like Trichocereus bridgesii or something similar.

These are PC by the way.

Hey mate, there's all kinds of Trichocereus around and not all are PC. If in doubt just post them here and we're happy to help with the identification. Close up photos are important though. Blurry group pics are usually not good enough. Ps: no discussion about alkaloids please.

First one is probably Neoraimondia herzogiana and the second one is Echinocactus grusonii. Definitely no Trichocereus, but nice plants. The Neoraimondia are just beautiful in Peru.

Hey mate, what error do you get?

First one is a Myrtillocactus geometrizans and the second one is a Trichocereus terscheckii.

Nope, it is definitely a Ferocactus. Google Images is a very bad tool to identify cacti. This rib structure is only present on Ferocactus and Gymnocalycium look totally different at this size.

Sorry, discussing ingestion of cacti isn't allowed here.

It's a Ferocactus. Could be Ferocactus glaucus, but not entirely sure which one it is.

Hey mate, first one is Stenocereus pruinosus, second one is Myrtillocactus geometrizans.

Dormancy is something that you get below 10° Celsius. Everything above isn´t really something I´d be worried about. The colder it gets, the slower these plants grow, but if your climate supports it you can still repot or root cuttings. Personally, I only use sand for rooting because it dries very fast and doesn´t cause problems with humidity below the cuts. If you have a rather organic soil, it will always trap humidity at the surface where your cut touches the soil. But yeah, other than this I wouldn´t worry a lot. Just make sure they stay dry and don´t get wet feet when it´s really cold.

Hi Hendry, very, very likely a PC. Don´t think it´s a Scop because the ribs arent bloated enough, and the overall spination just doesnt fit either. This is very close to PC and it´s a very variable plant that can look just like this. Would keep an eye on it and post it again when it´s bigger. Never say never, but everything other than PC would be surprising.

Almost certainly chemical burns. Did you use fertilizer, pesticides, oil, alcohol or anything similar on this plant? I´ve only seen this damage from Chemicals and mostly from oils and Neem.