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University of Illinois Extension

Daylily Leaf Streak

Aureobasidium microstictum 


5 (1= rare, 5 = annual)


4 (1 = little harm, 5 = death of plant) [fungus causes foliage to dieback to ground but does not kill the roots]


Hemerocallis sp. (Daylily)    


Aureobasidium microstictum causes reddish spots with yellowish margins that often result in brown streaks down the center of the leaves. Usually this leaf disease does not cause the death of the plant.

Don't confuse this disease with the relatively new (and much more important) disease called daylily rust, which is caused by Puccinia hemerocallidis.  

Life Cycle

The pathogen over-winters on dead plant material. It infects and causes dead leaves by mid to late summer.  


Fungicides and sanitation are helpful. However, if you are willing to accept poor aesthetic appearance by late summer, no treatment is needed. The plants will survive without any fungicide applications.

Filed under plants: Flowers

Filed under problems: Fungal Disease

More information is available on Hort Answers.