White to yellowish-green spots, up to ¼ of an inch in diameter develop on the leaves of Gaillardia. Light to dark brown spots can be seen in the center of these white spots. Leaf spots may later drop out leaving ragged holes.
This disease is caused by a fungus (Entyloma polysporum ). Fungal fruiting bodies (a complex fungal structure containing spores) are not seen on the surface of the diseased leaves. Microscopic examination of the internal leaf tissues is needed to see the fungal spores. This fungus may be seed-borne and may overwinter as resting spores in plant debris.
White smut is best managed with proper sanitation practices. Cut back plants; remove infected leaves or severely infected plants. During production, increase plant spacing to minimize disease spread by water splash from plant to plant.
