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Ecology and Epidemiology

The Mode of Systemic Infection of Sorghum and Sudangrass by Conidia of Sclerospora sorghi. B. L. Jones, Associate Professor, Texas A & M Agricultural Research and Extension Center, Weslaco, TX 78596, Present address: Texas A & M Agricultural Research and Extension Center, Stephenville, TX 76401; Phytopathology 68:732-735. Accepted for publication 14 October 1977. Copyright 1978 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-68-732.

Systemic infections with Sclerospora sorghi were obtained in sorghum and sudangrass by natural inoculation with conidia in the field and artificial inoculation with conidia in the greenhouse. Plants were most susceptible to systemic infection when inoculated the first night after seedling emergence. Sudangrass initially was more susceptible and it remained susceptible longer than sorghum. Penetrations by means of conidial germ tubes, were observed most often between epidermal cells of the stem at the soil surface. Hyphae advanced to the apical meristem of the plants and invaded developing leaves. It appeared that S. sorghi must enter leaves before they are fully developed for systemic symptoms to be expressed.

Additional keywords: downy mildew, fungal penetration.