|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
This publication is available in alternative media on request.