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Etiology, Incidence, and Distribution of Cotton Seedling Damping-off in Southern Spain. J. M. Melero-Vara, Research Plant Pathologist, Departamento de Protección Vegetal, Dirección General de Investigación y Extensión Agrarias, Apdo. 240, 14080 Córdoba. R. M. Jiménez-Díaz, Professor, Departamento de Agronomía, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad de Córdoba, Apdo. 3048, 14080 Córdoba, Spain. Plant Dis. 74:597-600. Accepted for publication 29 November 1989. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1990. DOI: 10.1094/PD-74-0597.

Disease surveys in 1980–1984 indicated widespread occurrence of cotton (Gossypium hirsutum) seedling damping-off in the Guadalquivir Valley of southern Spain. Dead seedlings occurred in 82–94% of the fields, with annual average incidences ranging from 6.6 to 9.4% dead seedlings per field. Fusarium spp., Rhizoctonia solani AG-4, Pythium ultimum, Thielaviopsis basicola, and Phytophthora palmivora MF1 A1, in order of decreasing frequency, were isolated from affected seedlings. Isolates of these fungi were pathogenic to cotton, except for those of Fusarium. R. solani AG-4 was the primary agent in the disease complex and was associated with severe necrosis of the root and/or hypocotyl. Pythium ultimum was associated with a watery decay of the root. Phytophthora palmivora MF1 A1 and T. basicola were minor components in the complex.

Keyword(s): Fusarium equiseti, F. oxysporum, F. solani.