Symptoms: Small, white, cushion-shaped sporodochia, circular to elongate (1.5 mm long), are formed singly and in clusters on leaves. Infected leaves become chlorotic and necrotic from the point of infection to the apex of the leaf.
Pathogen and disease characteristics: A network of aerial hyphae culminate in spirally twisted, corkscrew apices at the periphery of the sporodochium. Hyphae are hyaline to very light tan. Conidia are hyaline and spherical, averaging 10 µm in diameter. Spores may have imperceptible roughenings and may be borne in short chains.
Host range: Andropogon marginatus Steud., Chaetochloa poiretiana Hitchc. [=Setaria poiretiana (Schult.) Kuntz.], Panicum palmifolium Willd. (=Setaria palmifolia (Willd.) Stapf.), Pennisetum japonicum Trin., P. nepalense Spreng., P. purpureum Schumach, Setaria aurea Hochst., S. geniculata, S. verticillata (L.) Beauv., and Sorghum vulgare Pers.
Geographic distribution: On pearl millet: Malawi (Wiehe 1953), Tanzania (Mbwaga et al. 1993), Zimbabwe (Mtisi and de Milliano 1991). On other hosts: Japan, Java, Malawi, South Africa, Sudan, Trinidad, Uganda, United States, Zimbabwe.
Nomenclature discrepancies: Synonyms or similar pathogens: Albugo sp., Beniowskia penniseti Wakefield, B. sphaeroideum Kalchbr. & Cke., Ceratium sphaeroideum Kalchbr. & Cke.
Seed transmission: Not known to be transmitted by seed.
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Original posting: June 5, 1999.