Dahlia Diseases

Informational table showing disease name, symptoms, pathogen/cause, and management of Dahlia diseases.
Dahlia Diseases - Articles


Aster YellowsLeaf-like tissue forms where flower parts should be located. Flower-like parts remain green or light green.PhytoplasmaDestroy infected plants. Control leafhoppers.
Bacterial Stem RotBlackened stems have a soft, wet, interior and a foul odor.Erwinia carotovoraPromptly destroy infected plants
Gray MoldIn wet weather, masses of gray spores form on brown spots on buds, leaves or stems.Botrytis cinereaMaintain low relative humidity. Apply a fungicide to protect healthy plants.
Powdery MildewDry, white, mealy, fungal growth occurs on the upper surface of leaves.Golovinomyces cichoracearum (formerly Erysiphe)Apply a fungicide when the fungus is first observed.
Storage RotTubers decay into a soft smelly mass.Various fungi and bacteria.Avoid wounding the tubers. Let the tuber surfaces dry and remove soil before storing. Store tubers in a cool, dry location.
Verticillium WiltSingle branches or the entire plant wilts and dies. Vascular tissue in affectes stems is black, dark brown, or greenish-brown.VerticilliumPlant in pathogen-free potting mix.
VirusConspicuous rings and line patterns may be present or a mosaic of light and dark green may occur on leaves.Impatiens necrotic spot virusDiscard infected plants. Do not save tubers from affected plants. Control thrips since they vector the virus.

Prepared by Gary W. Moorman, Professor of Plant Pathology