Spring Sickness is considered a “mystery” disease – its cause is not known for sure, but it is definitely more prevalent in those areas where there are freeze / thaw cycles. Day lilies (Hemerocallis spp.) There may be a fungus involved but that has not been confirmed. The exact cause of Spring Sickness remains a mystery, and it appears in daylilies throughout zones 3-9 in the United States. thesis, Ohio State University. ... Update; this year in my neck of the woods, very cold and wet spring. Recovery and normal blooms occurring that season are uncertain. Occurrence and Injurious Effects of Rhizoglyphus echinopus - … … Labanowski, G.S., Soika, G. 1992. Daylily Pests. Typically the entire daylily clump is not affected -- usually it's only a couple of fans. Aphids are a common pest in most gardens and daylilies are not immune to their spa sucking habits. are known for being generally disease-resistant, but they occasionally develop fungal problems in conditions of high moisture. Spring sickness happens in areas where the winter is much milder than yours. Aphids. Some plants die from the top down. I’d never heard of this disease before the spring of 2012. According to AHS, spring sickness occurs in early spring with daylilies showing discolored, twisted, bent, or stunted foliage on some of the daylily’s fans. A fungus of … This daylily "Summer Wind" looked really wonky by the time I had gotten the weeds away from it. Spring Sickness normally occurs in areas that have a number of freeze/thaw cycles. There is not a definitive answer for why this happens. Leaves Spotted Due To Spring Sickness Occasionally the leaves of daylily plants develop yellow spots or brown blotches or streaks on them or new growth that looks rough. Day Lilies' Diseases and Their Cures. Aureobasidium microstictum (Bubak) Cooke, The causal agent of leaf streak of daylily (Hemerocallis L.) and its involvement in spring sickness of daylily, M.Sc. They don't bloom as heavily as they should. There was a study published in the AHS Daylily Journal several years ago (Summer 2010) that seemed to show some ss reduction with an insecticide and also with a fungicide (separately as far as I recall). But it did not prevent spring sickness completely. While daylilies have a reputation as being disease free, there are some plant diseases that affect daylilies, most notably, Daylily Rust has been a cause for recent concern. There may be several contributing factors to this daylily issue including bulb mites and leaf streak fungus.