|Bacterial Soft Rot||Yellowing plants wilt and die rapidly. Corms have a wet, soft rot.||Erwinia carotovora or Erwinia chrysanthemi||Plant only healthy, sound corms. Discard infected plants. Plant in pasteurized media.|
|Botrytis Blight||Leaf spots become tan in color. Flower petal spots are at first water-soaked but become tan. Infected crowns, petioles, and developing flowers are covered with gray fungal growth.||Botrytis cinerea||Reduce the humidity in the greenhouse. Space plants to insure good air circulation. Apply a fungicide to protect healthy plants.|
|Fusarium Wilt||Infected plants become very yellow. Vascular tissue in the corm turns dark brown to black. Mature plants wilt and die.||Fusarium oxysporum f. sp. cyclaminis||Plant sound, disease-free corms in pasteurized media. Discard infected plants.|
|Leaf Spot||Yellow or brown or gray circular spots develop on leaves and may have a zonate pattern within them. Small dark brown dots can be seen within the spots.||Septoria, Gloeosporium, or Phyllosticta||Water plants in a manner that does not wet the leaves. Apply a fungicide to protect healthy plants.|
|Pythium Root Rot||Young plants die. Stunting and root rot occurs on older plants.||Pythium||Plant in pasteurized media. Keep hose ends off the ground. Discard infected plants.|
|Thielaviopsis Root Rot||Stunted plants have blackened roots.||Thielaviopsis basicola||Plant in pasteurized media. Discard infected plants.|
|Viruses||Flowers may be abnormal in shape. Leaves are deformed and streaked with yellow or brown markings or have ringspots in a thumb-print like pattern.||Tobacco mosaic, cucumber mosaic, tobacco rattle, tomato aspermy, potato virus X, impatiens necrotic spot||Discard infected plants. Maintain good aphid and thrips control. Wash hands thoroughly and frequently when handling plants to prevent mechanical spread.|
Impatiens necrotic spot virus symptoms on leaves and flowers (Photos by F. E. Gildow, Penn State)
Prepared by Gary W. Moorman, Professor of Plant Pathology
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