over time I have seen several patches of heucheras up and die. this past week I decided to clean up and found at least 1/3 of the plants in various parts of the garden had died off...looks moldy to me. this has happened for the past several yrs with summers being wet, damp, extra dry, etc. is this a fungus in the soil, a bug/worm/slug carrying disease. i'm ready to pull them all out and quit.