I have a mounted Dendrobium Kingianum, which when first purchased grew new roots very well and has seemed to have taken to the mount. However, upon inspection today one of the roots has stopped growing and the white outer covering of the root has overtaken the green root tip. Is this cause for concern? Has it just stopped growing? There are three or four other roots on the plant that still have green root tips but have not actively grown in two weeks or so. I believe this is due to the lack of sunlight with the coming winter.

Thoughts, opinions?

Thanks!