Amaryllis, Hippeastrum sp. hybrids, are widely grown throughout the United States. With their large lily-like flowers, they are prized as house plants in the North and in outdoor gardens in the subtropical South. The flowers range in color from orange, yellow, green, and red to pure white. All species of Hippeastrum are native to tropical and subtropical America, from Mexico and the West Indies south to Chile and Argentina (7).
The most common fungus disease of amaryllis is caused by Stagonospora curtisii (Berk.) Sacc. The disease is variously known as red leaf spot, red blotch, and red fire (2). The same fungus also attacks Narcissus spp. causing the disease known as leaf scorch (1). The fungus also affects a large number of other amaryllids (6).
Fig. 1. Red leaf spot of amaryllis showing characteristic elongate sunken lesions.
Contribution No. 411, Bureau of Plant Pathology, P. O. Box 1269, Gainesville, FL 32602.
1. Creager, D. B. 1933. Leaf scorch of narcissus. Phytopathology 23: 770-786.
2. Creager, D. B. 1959. Red leaf spot of amaryllis. Fla. State Plant Board, Plant Pathol. and Nematol. Lab Note 22. 4 p.
3. Forsberg, J. L. 1963. Diseases of ornamental plants. Univ. III. Spec. Publ. 3. 208 p.
4. Gill, D. L. 1954. Reducing amaryllis leaf spot by spraying. Plant Dis. Reptr. 43:1272-1273.
5. Mullin, R. A., and T. A. Kucharek, eds. 1971. Florida plant disease control guide. Inst. Food & Agr. Sci., Univ. Fla., Gainesville, p. II-10.
6. Smith, C. O. 1935. Inoculations of Stagonospora curtisii on the Amaryllidaceae in California. Phytopathology 25:262-267.
7. Traub, H. P. 1958. The amaryllis manual. The Macmillan Co., New York. 338 p.