Brown Leaves on Cana Lillies
 

Can anyone tell me what this is, and is there a way to combat it?:

When I planted Cana Lilies about four years ago, then came in wonderfully
and looked totally healthy. In subsequent years, shortly after the leaves
develop, the leaves are brown, dry, and wilting around the edges, and the
plants look terrible. Some adjacent leaves look perfectly healthy, but most
are in bad shape.

Any thoughts?

Jim