A couple years ago I planted out a Nolina seedling. It was Nolina erumpens I collected myself in west Texas. Of course the winter before last barely hit 15F and it was fine. This winter, it actually appeared green for the most part, with only some of the longer needles browning. However, I just pulled on a green needle and it pulled off. Mind you the thing is still very tiny, longest leaf is only 4" or so.
Should I:
1) cover with glass pane (what I've done now)
2) cover with glass pane + treat with antifungal copper solution
3) dig entire plant immediately and try to get it growing again inside
4) give up - it's dead!