I have maiden hair grass that is about three years old. There are five different plants and they did really well until the last couple of weeks. One is still green with the plumes above the grass, but the others are yellow and brown with the plumes either not there or they are barely coming up. One looks especially bad. I did see some black "ish" spots on the old dried up stems. Looks almost like a leaf fungus? Does anybody know how to nurse them back to health? Should I just wait and cut them way back in the Spring and see what happens? Thanks so much for any help.