It is the time to degraft them because grafting stocks have been weak.
Since the grafting joint is embed deep in the scion when Hylocereus was used as the stock, I decided to go to the degrafting with vascular bundle of the stock.
I have experience this method many times with Astrophytum and Ariocarpus.
Scion with stock, soft-tissue of the stock around joint has already died.
The scion is Ariocarpus retusus v major.
Cut stock and removed soft-tissue of the stock
You can see a long vascular bundle of the stock.
Adjust length of vascular bundle of the stock, 20 mm length
Set the scion on a pot, top-dressing is scoria.
The pot is 12 cm square pot.
Roots will come out from the vascular bundle initially and alive a wile.
When the vascular bundle died, roots come out from the scion, no tap-roots, fine roots only.