Ergot

Systematic position and pathogen nature: Claviceps purpurea belongs to the kingdom Fungi, phylum Ascomycota. It is an obligate parasitic fungus that specifically infects the ovaries of various grass species. In agronomy, it is the primary causal agent of the disease known as ergot, which is characterized by the formation of dark, hard fungal masses that replace the host plant's healthy seeds.

Host crops and symptoms: The fungus affects a wide range of monocots, including rye, wheat, barley, triticale, and many wild grasses. The first visible symptom is the secretion of "honeydew," a sugary fluid containing conidia, which appears during the flowering stage of the host. Later, this fluid is replaced by the development of dark, horn-shaped sclerotia, known as ergot bodies, which protrude from the glumes.

Biology and life cycle: The life cycle begins with the germination of overwintered sclerotia in the soil. During the flowering period of host grasses, these sclerotia produce stalks that release ascospores into the air. These spores infect the ovaries of the developing grains. Following infection, the fungus produces secondary spores (conidia) that can be spread by rain or insects, leading to the infection of neighboring grains within the same or adjacent ears.

Conditions and pathogenicity: Ergot thrives in cool, humid, and rainy weather conditions during the crop's flowering phase. The pathogenicity of Claviceps purpurea is significant due to both yield losses and the presence of toxic ergot alkaloids. Consumption of grain contaminated with sclerotia poses severe health risks to humans and livestock, as the alkaloids are psychoactive and can cause physiological damage known as ergotism.

Protection and management measures: Controlling ergot requires integrated crop management strategies:

• Sowing certified, ergot-free seeds.
• Implementing crop rotation with non-grass species to break the life cycle.
• Performing deep plowing to bury sclerotia, making it impossible for them to germinate at the surface.
• Removing grass weeds from field borders and ditches.
• Using advanced gravity tables and color sorters during grain cleaning to remove ergot bodies from the final harvest.