Delphinium Diseases
Gary W. Moorman, Professor of Plant Pathology
| Disease | Symptoms | Pathogen/Cause | Management |
|---|---|---|---|
| ASTER YELLOWS | Leaf-like tissue forms where flower parts should be located. Flower-like parts remain green or light green. Often flowers on only one side of the spoke show sympotms. Sepals may be very large or dwarfed. | Phytoplasma | Destroy infected plants. Control leafhoppers. |
| BACTERIAL BUD ROT, CROWN ROT, AND STEM ROT | Yellowed leaves and stunting occurs. Blackened stem bases around cracks and wounds mark the point of entry. Smelly ooze forms under wet conditions. Infected stems topple. | Erwinia carotovora and Erwinia chrysanthemi | Promptly destroy infected plants. Avoid overhead irrigation. |
| BACTERIAL LEAF SPOT | Black, irregularly shaped spots form on leaves. Seedlings are killed. | Pseudomonas syringe | Destroy infected plants. |
| DIAPORTHE BLIGHT | As the plants flower, lower leaves brown and die. Brown spots form on the stems at the soil line and expand upward several inches. Small, black, pimple-like fungal fruiting structures develop on infected tissue. | Diaporthe | Destroy infected plants. Use seed known to be free of the fungus. |
| FUSARIUM WILT AND CANKER | Small brown spots form on stems and enlarge. Brown, sunken lesion may occur on petioles. Stem cankers may be dark brown and 12 inches long. As the canker tissue dies, masses of pink spores form in clumps. Wilting plants have vascular tissue that is browned. | Fusarium oxysporum | Destroy infected plants. |
| POWDERY MILDEW | Dry, white, mealy, fungal growth occurs on the upper surface of leaves. Leaves turn yellow, die from the base of the stem upward. | Erysiphe polygoni | Apply a sulfur, triadimefon, triforine, propiconazole, ziram, myclobutanil, or fenarimol when the fungus is first observed. Destroy plant debris at the end of the season. |
| STORAGE ROT | Tubers decay into a soft smelly mass. | Various fungi and bacteria. | Avoid wounding the tubers when digging them for storage. Let the tuber surfaces dry after digging and removing soil and before storing. Store tubers in a cool, dry location. |
| VIRUS | Conspicuous rings and line patterns may be present and plants are stunted. | Cucumber and tobacco mosaic viruses. | Destroy infected plants. |
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.) |
|---|---|---|---|---|---|
| 3 | 2 | Pyrimidine | fenarimol | 12 | Rubigan (62719-134) |
| Piperazine | triforine | 12 | Triforine (241-355) | ||
| Triazole | propiconazole | 24 | Banner MAXX (100-741), Propiconazole (51036-403), Spectator (62719-346-10404), Kestrel (66222-41-81943) | ||
| triadimefon | 12 | Strike (3125-436), Bayleton (432-1360) | |||
| myclobutanil | 24 | Systhane (707-253) | |||
| M | 1 | Dithiocarbamate | ziram | 48 | Ziram (4581-140) |
| NC | 1 | sulfur | 24 | Kumulus (51036-352) |
DISCLAIMER
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.
Issued in furtherance of Cooperative Extension work, Acts of Congress, May 8 and June 30, 1914, in cooperation with the U. S. Department of Penn State College of Agricultural Sciences research and extension programs are funded in part by Pennsylvania counties, the Commonwealth of Pennsylvania, and the U.S. Department of Agriculture.
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