Symptoms: On pearl millet: small, reddish brown to reddish orange, round to elliptical uredinia develop mainly on foliage. As severity of infection increases, leaf tissue will wilt and become necrotic from the leaf apex to base. In infection sites developing late in the season, uredinia are replaced by telia, which are black, elliptical, and subepidermal.
Pathogen and disease characteristics: P. substriata var. indica is a macrocyclic rust with the uredinial, telial, and basidial stages formed on pearl millet. Urediniospores are generally elliptical, measuring 35 × 25 µm, with four equatorial germpores. Spores have yellowish brown walls and are sparely echinulate, more predominantly near the apex. Teliospores are generally two celled, although this can vary. Dark brown, club-shaped spores measure 49 × 21 µm, and are borne on a pedicel. The spermagonial and aecial stages develop on the alternate Solanum hosts.
Uredinial sori may occasionally be parasitized by Darluca filum (Biv.), which forms pycnidia with two-celled conidia (Ramakrishnan and Narasimhalu 1941).
Host range: Uredinial hosts: Pearl millet, Panicum antidotale, P. maximum, Pennisetum orientale, P. violaceum. Also Pennisetum polystachyon (Ramakrishnan and Sundaram 1956).
Aecial hosts: Eggplant (Solanum melongena L.), S. torvum Sw., S. xanthocarpum Schrad & Wendl., S. anguivi Lam., S. ferox L., S. incanum L., S. linnaeanum Hepper & P. Jaeger, S. gilo Raddi, S. nodiflorum Jacq., S. rostratum Dunal (Wilson et al. 1996b), S. melongena var. insanum Prain, and S. pubescens Willd. (Ramakrishnan and Sundaram 1956). Euphorbia pulcherimma Willd. (Rao et al. 1986) has also been reported as an aecial host, but the report is subject to some question.
Geographic distribution: United States; also Brazil (C.T. Hash, personal communication, 1999).
Asia: India, Sri Lanka, Pakistan.
Africa: Chad, Congo, Ethiopia, Ghana, Guinea, Ivory Coast, Kenya, Malawi, Mozambique, Niger, Nigeria, Senegal, Sierra Leone, South Africa, Sudan, Tanzania, Uganda, Zambia, and Zimbabwe. Also Burkina Faso (S.B. King, personal communication, 1995).
Nomenclature discrepancies: Synonyms: Puccinia penniseti Zimm., Puccinia substriata Ell. & Barth. var. penicillariae (Speg.) Stat.
Other rust pathogens reported on pearl millet: Puccinia stenotaphri Cummins (Sathe 1969) [probably a synonym; the description of the fungus is similar to that in Wells et al. (1973)], Puccinia substriata Ell. & Barth. var. decrospora (Eboh 1986).
Seed transmission: Not known to occur.
Primary citation: Singh and King 1991.
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Original posting: June 5, 1999.