New canes don’t produce roots until they are about 1/2 to 3/4 grown. They get water and food from the older cane.

Dry and yellow sounds to me more like sunburn or heat damage. Is there chance that window gets hot during the day. How does the older cane it’s growing off of look?

I'm thinking it's heat damage, now. This started showing up when I moved it onto a heat mat. Temps here are in the 50s or 60s lately so I thought it would be best to move it to somewhere warmer. But I have a succulent on the same mat that developed sunburn a week ago. Maybe it's just too hot there?

Has it always been in that window? If so, I'd think it wasn't sunburn damage as it would have already been accustomed to that light level, even though the sun angle is changing to more of a southernly exposure. But then, Dends can handle some pretty bright light especially if eased into it over a few weeks or so.

In my experience Dend phals can easily handle zone 6 house temps without a need for a heat mat, so I wouldn't use the mat for the Den.

If the yellowing coincides with the use of the heat mat or the movement to a new location, that is a pretty good indicator that one of the two caused the issue.

Did the other roots look OK and how does the older cane look (per James)?

Good luck,

Bob

Then I think it's the mat. The roots are ok (sorta), they dried out in shipping and alot of them had to come off. It has a decent root system, just not as much as I wanted. I moved it to the heat mat to hopefully stimulate new roots and the yellowing started. Maybe I'm stressing it too much. I don't know why I didn't think of this myself. I'll move it back and hopefully it'll grow

The older cane looks great, it's just the new growth that's showing the yellowing