It has never adversely affected the plant, but it does make it look sick.

Not sure what the problem is. High nitrogen fertilizer helps green-up the leaves, but it doesn't like heavy fertilizer.

My grove is small and about 10 years old.

Kt

I don't think they really need misting or extra humidity because mine used to leaf curl a bit in the summer, but not anymore. They leaves I see this year are also way smaller than they were the previous years due to larger culms.