|Alternaria Leaf Spot||Brown specks form on florets and the leaves. Centers become white on the leaf spots.||Alternaria||Maintain low relative humidity and do not wet leaves when watering. Apply a fungicide to protect plants.|
|Bacterial Leaf Spot||Small to large spots are circular at first, then become irregular and dark brown to black. May have a concentric ring pattern.||Pseudomonas cichorii||Maintain low relative humidity. Avoid overhead watering.|
|Botrytis Blight||Petioles have long brown spots. Leaves yellow and die. Petals have tan spots. Stems at soil level are killed. Infected tissues become covered with gray fungal growth.||Botrytis cinerea||Space plants to insure good air circulation. Maintain low humidity. Avoid watering late in the day. Remove crop debris. Apply a fungicide to protect plants.|
|Fusarium Stem Rot||Petiole of leaves blacken at the base as the plant collapses.||Fusarium solani||Plant in pasteurized potting media. Discard infected plants.|
|Phytophthora Crown Rot||Plants wilt suddenly. Leaves brown. Roots are rotted and a crown rot develops.||Phytophthora cryptogea||Plant in pasteurized potting media. Avoid overhead watering. Apply a fungicide to protect plants.|
|Powdery Mildew||White fungal growth develops on the surface of leaves.||Golovinomyces cichoracearum (formerly Erysiphe)||Apply a fungicide to protect plants.|
|Pythium Root Rot||Plants wilt and die as roots rot.||Pythium||Plant in pasteurized potting media.Apply a fungicide to protect plants.|
|Rhizoctonia Crown Rot||Stems at the soil level have a brown lesion. Plants wilt and die.||Rhizoctonia solani||Plant in pasteurized media. Apply a fungicide to protect plants.|
|Thielaviopsis Root Rot||Plants yellow, wilt, and die. Roots are dark brown to black.||Thielaviopsis basicola||Plant in pasteurized media. Apply a fungicide to protect plants.|
|Viruses||Leaves may be mottled, have yellow spotting, dead flecks, line or ring spot patterns. Plants may be distorted or have flower color breaking.||Tobacco rattle, gerbera mosaic, impatiens necrotic spot, and cucumber mosaic viruses.||Maintain good insect and mite control. Plant in pasteurized media. Destroy infected plants|
Fusarium crown rot.
Prepared by Gary W. Moorman, Professor of Plant Pathology
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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.
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