Gary W. Moorman, Professor of Plant Pathology
|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 SPOTS||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)
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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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