Hemerocallis (Daylily) Diseases
Gary W. Moorman, Professor of Plant Pathology
| Disease | Symptoms | Pathogen/Cause | Management |
|---|---|---|---|
| Colletotrichum leaf spot or leaf scorch | Leaf tissue dies in a streak along the mid-vein. | Colletotrichum dematium | Remove infected leaves. Destroy leaf debris at the end of the season. Avoid overhead irrigation. |
| Leaf streak or Red leaf streak | 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. | Aureobasidium microstictum | 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 | Slender, grassy foliage develops and few flower stalks form. Crowns rot and die. | Rhizoctonia, usually following freeze injury. | Protect crowns from freezing. |
| Russet spot | Reddish spots form on the leaves. | Unknown. | |
| Rust | Bright yellow spots or streaks on the upper side of the leaf have bright yellow-orange spores on the underside.. | Puccinia hemerocallidis | This fungus also occurs on Patrinia spp. (and possibly Hosta, but this has not been observed in the U. S.). Most cultivars are susceptible. Remove infected leaves and immediately place them in a plastic bag for disposal. Keep the bag closed. Apply flutolanil, azoxystrobin, mancozeb, or chlorothalonil, weekly until the disease is under control. |
Active Ingredients and Trade Names of the Chemicals
| FRAC Group No. | Risk Level | Class | Active ingredient | REI Restricted Entry Interval | Trade names (EPA Reg. no.) |
|---|---|---|---|---|---|
| 1 | 3 | Benzimidazole | thiophanate methyl | 12 | 3336 (1001-69), OHP 6672 (51036-329-59807) Fungo Flo (51036-329-59807) Systec 1998 (48234-12) |
| 7 | Anilide | flutolanil | 12 | Contrast (45639-208-58185) | |
| 11 | 3 | Strobilurin | azoxystrobin | 4 | Heritage (10182-408) |
| 12 | 2 | Phenylpyrol | fludioxonil | 12 | Medallion (100-769) |
| M | 1 | Chloronitrile | chlorothalonil | 48 | Daconil (50534-9), Exotherm Termil (70-223) |
| 12 | Echo (60063-7), PathGuard (60063-7-499), Concorde (72167-24-1812), Pegasus (72167-24-1812) | ||||
| Dithiocarbamate | mancozeb | 24 | Dithane (707-180), FORE (707-87), Pentathlon (1818-251) | ||
| manganese + zinc | 24 | Protect T/O (1001-65) |
Fungicides and Fungicide Resistance Management - Certain fungicides, usually systemic fungicides, are said to be 'at risk' to the development of resistance if they are used repeatedly. See the Risk Level in the above table (1 = low risk; 3 = high risk). The Fungicide Resistance Action Committee has developed a numbering system in which chemicals with the same FRAC Group number have the same mode of action (See http://www.frac.info/frac/index.htm ). It is recommended that chemicals at high risk be used sparingly and in rotation or mixed with chemicals with different modes of actions (different FRAC number).
References
Holcomb, G. E. 1976. Daylily leaf-streak in Louisiana. Plant Disease Reporter 60:232-233.
Blosser, W. 2001. Daylily rust alert. Regulatory Horticulture 27:5-6.
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Notice: The user of this information assumes all risks for personal injury or property damage.
Warning! Pesticides are poisonous. Read and follow all directions and safety precautions on labels. Handle carefully and store in original labeled containers out of the reach of children, pets, and livestock. Dispose of empty containers right away, in a safe manner and place. Do not contaminate forage, streams or ponds.
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