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Heya guys. I have some issues with my grafted pereskiopsis and wanted to know what the issue might be http://imgur.com/gallery/egWtTlL
The first picture is a astro onzuka grafted about month ago. The leaf is starting to turn yellow from the tip out? Its been on fertilizer and only 2 grafts out of 40 is doing this.

2nd and 3rd pictures show this black hard thing on my pereskiopsis mother plants. No squishyness No pus And no bugs just as hard as the other parts of the pereskiopsis.

I'm not sure I'd worry too much about the leaf yellowing unless it keeps happening. I mean it's just one leaf on two plants right? And you didn't find any signs of bugs or fungus on the plant?

I don't know what the brown spots are. I see a lot of corking on the stems, but clearly the brown is different. Imo it's likely harmless. Maybe it's a fungus. Maybe it's this as yet unexplained phenomenon:

viewtopic.php?f=24&t=43894&p=367210

A general note here, it looks like your light is on the dimmer side (based on the thin leaves). I only grow Pereskiopsis in full sun and I don't know whether that's better or not but it's something to think about if your plants keep having random problems