Scouting for diseases: Daylily leaf streak
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EmailPathogen: Collecephalus hemerocalli. (view images)
Hosts: Hemerocallis.
Symptoms: Elongated brown lesions, which are lengthwise on the
foliage, surrounded by a chlorotic halo. Lesions that affect the midrib
of a leaf cause the leaf to senesce from the lesion to the leaf tip.
Tissue in the center of the leaf becomes necrotic, creating a dead
streak down the middle of the infected leaf. Flower production may be
decreased.
Spread: Diseased plant material can introduce the pathogen into
a production area. C. hemerocalli produces wind-borne spores on
infected leaves. Sclerotia, an overwintering structure, are produced on
dead or dying foliage.
Management: Cultivars vary in their susceptibility. Remove dead
foliage from the preceding year. Poorly managed plants in overcrowded
growing situations are more likely to become diseased. The disease is
more severe early in the growing season. Temperatures above 90°F limit
disease development.
Information is from the new field guide A Pocket Guide for IPM Scouting in Herbaceous Perennials. Ordering information, call 517-353-6740 or visit: http://www.ipm.msu.edu/pdf/pocketGuidesLandsc07.pdf
