Goldenrod (Solidago) Diseases
Gary W. Moorman, Professor of Plant Pathology
|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 thiophanate methyl or Bacillus subtilis to protect leaves not yet infected.|
|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 polyoxin, thiophanate methyl, potassium salts of fatty acids, neem oil, jajoba oil, petroleum oil, or copper hydroxide.|
|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 pyraclostrobin + boscalid, thiophanate methyl, propiconazole, potassium bicarbonate, Bacillus subtilis to protect leaves not yet infected.|
|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.|
Warning! Pesticides are poisonous. Read and follow all directions and safety precautions on labels. Handle carefully and store in original labeled containers out of the reach of children, pets, and livestock. Dispose of empty containers right away, in a safe manner and place. Do not contaminate forage, streams or ponds.
Issued in furtherance of Cooperative Extension work, Acts of Congress, May 8 and June 30, 1914, in cooperation with the U. S. Department of Penn State College of Agricultural Sciences research and extension programs are funded in part by Pennsylvania counties, the Commonwealth of Pennsylvania, and the U.S. Department of Agriculture.