I have had a huge yucca removed, and the roots were poisoned and then removed. The earth is still full of roots, but I am not sure which ones belonged to the yucca. There are a lot which seem to have a red core inside a brown outer layer. Are these from the yucca, or maybe from roses? I don't know if I can pull them out or not. Thanks a lot.
Dead roots will be hard and brittle, or soft and mushy. Scrape a bit off the outside of the roots - if the tissue is still moist, the root is still alive.