Goldenrod (Solidago) Diseases
|Rust||Small, bright orange, yellow, or brown pustules on the underside of leaves.||Coleosporium, Puccinia or Uromyces||Provide good air circulation. Clean up all debris. Avoid overhead watering. Golden Fleece and Fireworks are reported to be resistant to rust and powdery mildew. Apply a fungicide to protect plants.|
|Powdery mildew||The powdery white or gray fungus is most evident on the upper surface of leaves. Leaves will often turn yellow or brown, curl up, and drop off; new foliage emerges crinkled and distorted. Use the same methods that are described for the control rusts above.||Golovinomyces, Erysiphe, Uncinula, Phyllactinia, Sphaerotheca||Provide good air circulation and avoid overhead watering. Golden Fleece and Fireworks are reported to be resistant to powdery mildew and rust. Apply a fungicide to protect plants.|
|Fungal leaf spots||Small, dark spots of fungal infection tend to appear first on lower leaves. Leaves with numerous spots may turn yellow, then brown, and wither.||Ascochyta, Asteroma, Cercospora, Colletotrichum, Macrophoma, Phyllosticta, Placosphaeria, Ramularia, Septoria.||Avoid overhead watering, space plants adequately to insure rapid drying, and water early in the day. Apply a fungicide to protect plants.|
|Bacterial leaf spot||Dark brown to black spots form on the leaves.||Xanthomonas sp.||Avoid overhead watering, space plants adequately to insure rapid drying, and water early in the day.|
|Aster yellows||Plants become yellowed and flowers lack their usual coloration. Tight clusters of leaves may form.||Phytoplasma||Remove and destroy infected plants. Apply insecticides to suppress leafhoppers that spread the pathogen.|
|Crown gall||Galls or swollen areas form at the soil line or sometimes higher where the plant had been wounded.||Agrobacterium tumefaciens||Start with healthy plants that are free of any galls. Remove and destroy infected plants.|
|Lesion nematodes||Roots may be stubby with darkened areas along their length.||Pratylenchus pratensis||Remove and destroy infected plants. Replant with non-host species.|
|Virus||Yellow or brown rings form on leaves or leaves may be yellowed in a mottled pattern. Plants may be stunted.||Tomato spotted wilt virus (TSWV)||Infected plants should be removed and destroyed. Use insecticides to suppress the insect that spreads the virus, western flower thrips.|
Prepared by Gary W. Moorman, Professor of Plant Pathology
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