Informational table showing disease name, symptoms, pathogen/cause, and management of Gaillardia diseases. Disease Symptoms Pathogens/Cause Management Aster yellows Leaves are yellowed and flowers do not appear normal or of good quality. Phytoplasma (bacterial-like organism) Remove and destroy infected plants. Control leafhoppers early in the season with insecticides in order to suppress spread of the pathogen from weeks to your plants. Bacterial leaf spot Areas between veins turn dark brown and collapse. The entire plant may be killed Pseudomonas Remove and destroy infected plants. Do not use sprinkler irrigation. White smut At first light green spots, some with tan centers, form on the leaves and white spores form on the spots. The leaf spots become dark brown. Entyloma spp. Remove and destroy spotted leaves. Apply a fungicide to protect plants. Septoria leaf spot Tan spots containing tiny dark brown to black dot-like fungal fruiting structures form on the leaves. Septoria Do not use sprinkler irrigation. Powdery mildew White fungal growth develops on the surface of leaves. Golovinomyces and Sphaerotheca Apply a fungicide to protect plants. Root and stem rots Lower stems turn tan to dark brown. Sometimes white webs of fungal growth can be seen. Pythium, Sclerotinia, Thielaviopsis, Rhizoctonia Avoid overwatering and do not mound mulch against the plant. Viruses Leaves may be distorted or have patches of light and dark green coloration Impatiens necrotic spot, tomato spotted wilt, or and cucumber mosaic virus Remove and destroy infected plants. Control thrips (vector of impatiens necrotic spot and tomato spotted wilt) and aphids (vectors of cucumber mosaic).

Smut

Septoria leaf spot

Prepared by Gary W. Moorman, Professor of Plant Pathology