How about digging the earth away from the crown and cutting all the greenery down to very near the crown. I am sure it would not be a 100% cure, but I am asking if it would have a significant deterrent effect?
I don't remember why but I always thought it would be good to spray the daylily foliage with a fungicide then cut it back, but then I read you should cut it back then spray. Which is actually best or does it matter?