According to this lengthy dissertation, the severity of a couple of rusts (not daylily) did not significantly differ between compost-amended and control plots. Rust tended to be worse on manure amended plots
https://www.ideals.illinois.ed...
In the summary the author concludes "Data from the field pointed to the fact that building up organic matter does not automatically guarantee disease suppression. Manure supplied more labile carbon and nitrogen, induced higher microbial activity and produced higher biomass, yet it promoted certain diseases, especially with biotrophic pathogens like rust......"
