Symptoms: Cream to pink mucilaginous droplets of "honeydew" ooze out of infected florets on pearl millet panicles. Within 10 to 15 days, the droplets dry and harden, and dark brown to black sclerotia develop in place of seeds on the panicle. Sclerotia are larger than seeds and are irregularly shaped. They generally get mixed with the grain during threshing.
Pathogen and disease characteristics: Sclerotia germinate to form 1 to 16 fleshy stipes, 6 to 26 mm long. Each stipe bears an apical, globular capitulum, light to dark brown, with numerous perithecial projections. Asci are interspersed with paraphyses and emerge through ostioles. Threadlike ascospores are hyaline, aseptate, and measure 100-170 × 0.5-0.7 µm.
Sclerotia germinate following rain. Ascospores infect emerged stigmas before pollination. Conditions favoring the disease are relative humidity greater than 80 percent and 20 to 30 °C temperatures. Honeydew production promotes secondary infection caused by asexual conidia. Honeydew consists of two types of asexual conidia.
Host range: Pearl millet, Cenchrus ciliaris, Panicum antidotale, Pennisetum hohenackeri Hochst. Also P. squamulatum and P. massaicum (Dwarakanath Reddy et al. 1969).
THIS PATHOGEN HAS NOT BEEN REPORTED ON PEARL MILLET IN THE UNITED STATES AND ALL EFFORTS TO RESTRICT ITS ENTRY SHOULD BE CONTINUED.
Countries where pearl millet ergot has been observed or reported include:
Africa: Botswana, Burkina Faso, Gambia, Ghana, Malawi, Niger, Senegal, Somalia, Tanzania, Uganda, Zambia, Zimbabwe. Also Benin, Cameroon, Chad, Togo, Ivory Coast, Kenya, Mali, Nigeria, Sudan (S.B. King, personal communication, 1995).
Asia: India, Pakistan.
Nomenclature discrepancies: Synonyms or similar pathogens: Claviceps microcephala (Wallr.) Tul., Sphacelia spp., Cerebella sorghi-vulgaris Subram. (Wallace and Wallace 1949).
Alternative disease name: Asali disease.
Seed transmission: Sclerotia can contaminate seed lots. A 10-percent NaCl solution is effective for separating sclerotia and fragments from seed by flotation. This technique can be used only for relatively small quantities of seed. Sclerotia can be removed from small individual seedlots by hand.
Primary citation: Thakur and King 1988.
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Original posting: June 5, 1999.