Zinnia Diseases

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

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DiseaseSymptomsPathogen/CauseManagement
Alternia Leaf SpotLarge reddish brown or purple spots, at first round to oblong but becoming irregular in shape have gray or tan centers that may drop out leaving a hole. Severely affected leaves brown, dry, and become brittle.Alternaria zinniaeApply a fungicide. Whenever possible, water in a manner that keeps the leaves dry to inhibit this seedborn disease.
Aster YellowsLeaf-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.PhytoplasmaDestroy infected plants. Control leafhoppers.
Bacterial Leaf SpotSpots reddish brown to dark brown, angular and with a prominent yellow halo form on leaves.Xanthomonas campestris pv. zinniaeNo sprays are effective. Whenever possible, water in a manner that keeps the leaves dry to inhibit this seedborn disease.
Powdery MildewWhite fungal growth forms on the upper surface of leaves and may form on flower petals.Golovinomyces cichoracearum (formerly Erysiphe)Apply a fungicide to protect plants.


Alternaria leaf spot. Bacterial leaf spot (those with yellow halo)


Alternaria leaf spot (purple spot, no halo).

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