Daylily Perennial Shrub Diseases:
Colletotrichum Leaf Spot or Leaf Scorch:
Symptoms-Leaf tissue dies in a streak along the mid-vein.
Management-Remove infected leaves. Destroy leaf debris at the end of the season. Avoid overhead irrigation.
Leaf Streak or Red Leaf Streak:
Symptoms-Reddish fleck form on the leaves as the mid-vein yellows. Oval dead spots form and the leaves die prematurely. During wet conditions wet, shiny masses of white spores can be seen with a hand lens on the brown leaves.
Management-Remove infected leaves. Destroy leaf debris at the end of the season. Avoid overhead irrigation. Cultivars vary greatly in susceptibility. Protect new leaves with thiophanate methyl.
Rhizoctonia Crown Rot:
Symptoms-Slender, grassy foliage develops and few flower stalks form. Crowns rot and die.
Management-Protect crowns from freezing.
Symptoms-Bright yellow spots or streaks on the upper side of the leaf have bright yellow-orange spores on the underside.
Management-Remove infected leaves and immediately place them in a plastic bag for disposal. Keep the bag closed. Apply flutolanil, azoxystrobin, mancozeb, or chlorothalonil, weekly.