Symptoms: Sphacelial (conidial) "honeydew" sporulation has been reported on pearl millet (Frederickson and Mantle 1996). Formation of sclerotia has not been reported.
Pathogen and disease characteristics: Occurrence of the disease has usually been the result of artificial inoculation, except for the observation by Sundaram (1974), which, because of the location, may have been Claviceps sorghi.
From sorghum: Sclerotia (4-6 × 2-3 mm) bear a small distal sphacelial cap. White medulla is bound by thin red-brown cortex. Flower parts are persistent on sclerotia. Stromata are initially pale, translucent, and proliferate from sclerotium at one or two places. Stipes are purple in distal part of stipe. Stipes measure 8-15 × 0.3-0.6 mm; capitula are subglobose, 0.5-1.3 mm; perithecia measure 86-135 × 123-226 µm; ascospores usually up to 45 × 0.8-1.2 µm. Macroconidia are hyaline, mononucleate, oblong to oval, slightly constricted at center with a vacuole at each end, 9-17 × 5-8 µm. Microconidia are hyaline, mononucleate, spherical, 2-3 µm diameter (Frederickson et al. 1991).
Host range: Sorghum, pearl millet, guineagrass (Panicum maximum). The literature is not clear.
Geographic distribution: Infection on pearl millet has been observed in Zimbabwe and possibly in Nigeria and India. Geographic distribution of the pathogen on sorghum is wider than that reported for pearl millet.
Nomenclature discrepancies: The literature suggests cross-infection of pearl millet with Sphacelia sorghi McRae. Futrell and Webster (1966) reported that 1 percent of inoculated florets became infected in Nigeria. Sundaram (1974) reports infections in India, with subsequent cross-inoculations onto sorghum and pearl millet. Few experimental details are described. Dwarakanath Reddy et al. (1969) produced 20-percent infection on pearl millet. Frederickson and Mantle (1996) achieved successful inoculations with C. africana. Frederickson et al. (1991) indicate that there are at least two Claviceps species--C. africana and C. sorghi--that have been lumped under Sphacelia sorghi in the literature.
Seed transmission: No information available. Literature does not indicate if sclerotia form in pearl millet.
Primary citation: Frederickson and Mantle 1996.
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Original posting: June 5, 1999.