White smut

Rusts and smuts

Pathogen

Entyloma polysporum.

Hosts

Aster, Echinacea, Gaillardia, Helianthus and Rudbeckia.

Symptoms

Round, white spots, up to 1 centimeter in diameter. Young lesions may create very faint spots. Over time, the spots turn brown and become necrotic.

White smut gaillardia foliage
Whitish, round lesions on Gaillardia foliage.

Spread

Spores are formed inside the leaf tissue. As lesions mature, the leaf surface ruptures, releasing the spores.

White smut lesions
Older lesions caused by white smut on Gaillardia have coalesced and are causing necrosis.

Spores are wind-dispersed. A white, powdery material may be visible on the leaf surface. Spores of this fungus are not known to survive winters in the northern United States.

Management

Remove all symptomatic plants. Plants in greenhouses may need fungicide applications for good disease control. The disease is favored by cool, humid conditions; disease spread will be slow under warm, dry conditions.

Note

Of the hosts listed, Gaillardia is most susceptible. The disease has been documented on the cultivars ‘Goblin’, ‘Baby Cole’ and ‘Fanfare.’ This disease has been seen with increasing frequency in the past few years.

White smut gaillardia planting
Dieback caused by a severe white smut infestation on a landscape planting of Gaillardia.

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The MSU IPM Program maintains this site as an access point to pest management information at MSU. The IPM Program is administered within the Department of Entomology, fueled by research from the AgBioResearch, delivered to citizens through MSU Extension, and proud to be a part of Project GREEEN.