Claviceps africana Frederickson, Mantle, & de Milliano
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.
Department of Agriculture
The material on this page is in the public
Original posting: June 5, 1999.