I haven't seen anything like the exposed roots except when a sprinkler has gone berserk and washed the soil away! Questions I would have are how deep were they planted in the first place (depth of top of hard part of crown), what are they growing in (native soil, amended soil, clay, loam, sand, mostly soilless media), how well aerated is it, and what is the irrigation system (type, frequency etc.). Diagnosing plant problems always sounds like one is being given the third degree but it's really going through a necessary process of elimination. Daylilies are supposed to pull themselves down rather than up!
