Daylily
Symptom Cause  
Leaves wrinkled or curled; discolored, stunted, tend to fall off
Aphids
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Buds & leaves chewed or disappear
Deer
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Leaves develop yellow striping
Leaf Streak Fungus
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Leaves stippled; covered with webs
Mite
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Large; ragged holes in leaves
Slugs and Snails
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Black powdery sooty mold fungus forms on honeydew;
Sooty Mold
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Leaves spotted,twisted or pleated effect on the inner leaves, they will often grow sideways with a brown saw-toothed edge and holes. These can suddenly appear in the spring on healthy new leaves.
Spring Sickness
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Leaves discolored; plant distorted; black fecal spots near affected tissue.
Thrips
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