Claviceps

Claviceps is a genus of ascomycetous fungi in the family Clavicipitaceae. Members are obligate parasites of flowering grasses, infecting the inflorescences and replacing developing seeds with dark sclerotia. The most economically important species is Claviceps purpurea, which causes ergot diseases on rye and other cereals and grasses.

Biology: Infection starts when fungal spores land on immature flowers. The fungus colonizes the ovary, and the grain is replaced by a hard sclerotial body that accumulates ergot alkaloids. Sclerotia can overwinter in soil and debris and give rise to new infections in successive seasons. Infected heads yield sclerotia instead of grain, which are later disseminated when harvested.

Distribution and hosts: Claviceps occurs worldwide, with C. purpurea the most widespread and economically significant on rye, wheat, oats and related crops. Other Claviceps species infect sorghum, paspalum and other grasses.

Impact and control: Ergot contamination reduces yield and grain quality and poses risks of ergotism in humans and animals. Control measures include crop rotation, sanitation, resistant varieties, careful grain cleaning to remove sclerotia, and monitoring for ergot alkaloids; regulatory limits exist in many jurisdictions. Fungicides may reduce infection in some crops.

Chemistry and medical use: The ergot alkaloids produced by Claviceps, such as ergotamine and ergometrine, have vasoconstrictive and uterotonic properties. They are used medically for migraine and obstetric indications, but their toxicity requires controlled use. Historical outbreaks of ergotism, caused by ingestion of contaminated grain, are known as Saint Anthony's Fire.