Symptoms: Disease can be expressed as seed decay, pre-emergence and postemergence damping off, stem lesions on seedlings, or stem canker on more mature plants. Invasion of sheath and blade tissue can cause a banding pattern. The midrib is usually the last part of the leaf killed. Mature plants have considerable accumulation of dead brown leaves around the base. Individual culms may be killed. The root system is reduced, with extensive killing and discoloration.
Pathogen and disease characteristics:Rhizoctonia species often survive in soil as melanized hyphae and sclerotia, often associated with plant debris. R. solani forms yellow-brown, matlike stroma and distinct sclerotia in culture. R. zeae forms a white to pink mycelium and spherical, reddish brown sclerotia immersed throughout agar medium. Classification of Rhizoctonia species is currently based on hyphal characteristics and colony morphology in culture (Sneh et al. 1991).
Host range: Nearly all plants are susceptible to one or more anastomosis groups of R. solani or binucleate Rhizoctonia species. Some host specificity exists among the different anastomosis groups of R. solani. Pathogens of pearl millet have not been examined for anastomosis compatibility. R. zeae is primarily a pathogen of many different grasses.
Geographic distribution: On pearl millet: United States, Tanzania (Mbwaga et al. 1993).
Nomenclature discrepancies:Synonyms:Pellicularia filamentosa (Pat.) Rogers f. solani (Kühn) Exner.
Alternative names for the disease: Banded sheath, leaf blight, soil rot.
Seed transmission: Not known to be transmitted by seed. Konde et al. (1980) has reported isolation of Rhizoctonia bataticola from seed, but the fungus is now considered Sclerotium bataticola Taub [teleomorph: Macrophomina phaseolina (Tassi) G. Goid.] .
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Original posting: June 5, 1999.