Gary
Moorman
Professor of Plant Pathology |
|
Dahlia Diseases
| 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. |
Phytoplasm |
Destroy infected plants. Control
leafhoppers. |
| Bacterial Stem Rot |
Blackened stems have a soft, wet,
interior and a foul odor. |
Erwinia
carotovora |
Promptly destroy infected plants |
| Gray Mold |
In wet weather, masses of gray spores
form on brown spots on buds, leaves, or stems. |
Botrytis
cinerea |
Maintain low relative humidity. Apply
fludioxonil, iprodione, or mancozeb to protect plants. |
| Powdery Mildew |
Dry, white, mealy, fungal growth
occurs on the upper surface of leaves. |
Erysiphe
cichoracearum |
Apply Ampelomyces,
myclobutanil, ziram, mancozeb, thiophanate methyl + mancozeb,
fenarimol, triadimefon, or triforine when the fungus is first
observed. |
| 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. |
| Verticillium Wilt |
Single branches or the entire plant
wilts and dies. Vascular tissue in affected stems is black,
dark brown, or greenish-brown. |
Verticillium |
Discard infected tubers. Fumigate
infested soil before planting. |
| Virus |
Conspicuous rings and line patterns
may be present or a mosaic of light and dark green may occur
on leaves. |
Impatiens necrotic spot virus |
Discard infected plants. Do not save
tubers from affected plants. Control thrips since they vector
the virus. |
| COMMON NAME |
TRADE NAME |
| Ampelomyces quisqualis |
AQ10 (biological control agent) |
| copper |
Kocide, Basicop, Nu-Cop |
| etridiazole |
Terrazole, Truban |
| etridiazole + thiophanate methyl |
Banrot |
| fenarimol |
Rubigan |
| fludioxonil |
Medallion |
| iprodione |
Chipco 26019 |
| mancozeb |
Dithane, Protect |
| mancozeb + copper |
Junction |
| myclobutanil |
Eagle, Systhane |
| PCNB |
Terraclor, PCNB |
| piperalin |
Pipron |
| propamocarb |
Banol |
| thiophanate methyl |
Clearys 3336, Domain FL |
| thiophanate methyl + mancozeb |
Duosan, Zyban |
| triadimefon |
Bayleton, Strike |
| triforine |
Triforine |
| ziram |
Ziram |
|
|
