Disease Note.

First Report of Diseases on Lisianthus in Argentina. S. Wolcan, CIC-CONICET, Laboratorio de Fitopatologia, Facultad de Ciencias Agrarias y Forestales UNLP, 60 y 119, 1900 La Plata, Buenos Aires, Argentina. L. Ronco, E. Dal Bo, G. Lori, and H. Alippi, CIC-CONICET, Laboratorio de Fitopatologia, Facultad de Ciencias Agrarias y Forestales UNLP, 60 y 119, 1900 La Plata, Buenos Aires, Argentina. Plant Dis. 80:223. Accepted for publication 21 November 1995. Copyright 1996 The American Phytopathological Society. DOI: 10.1094/PD-80-0223A.

During the late 1980s lisianthus (Eustoma grandiflora (Raf.) Shinn.) was introduced in Argentina as an alternative cut flower. Greenhouse production is located in La Plata and Florencio Varela, not far from Buenos Aires. Climatic conditions, especially high relative humidity, enhance some diseases resulting in losses of economic significance. From 1988 to 1994 four diseases were detected for the first time in Argentina. This is the first record for two of these diseases on lisianthus: (i) Tomato spotted wilt virus (TSWV), which was detected in 1994. The symptoms included stunting and light brown necrotic rings and spots on the lower leaves. The response of indicator hosts and enzyme-linked immunosorbent assay using impatiens necrotic spot virus, TSWV, and groundnut ringspot virus antibodies demonstrated that TSWV was the causal agent, (ii) Stem rot {Sclerotinia sclerotiorum (Lib.) de Bary), which causes a soft rot with white mycelium on the stem and black sclerotia inside the pith. The fungus was isolated and Koch's postulates were fulfilled. The diseases previously reported in other countries are gray mold (Botrytis cinerea Pers.:Fr.) (1), whose symptoms are crown and basal leaf rot with grayish mycelium and spore masses over the surface, and downy mildew (Peronospora chlorae de Bary) (I), which produces the typical white mycelial patches on the leaves.