Ergot
Claviceps purpurea
Overview
A fungal disease of cereals and grasses that replaces grain kernels with dark, hard sclerotia containing toxic alkaloids. Historically caused ergotism (St. Anthony's Fire) in humans consuming contaminated grain. Ergot spreads mainly by spores on wind, splash, tools, and crop debris. Humid, crowded plantings and overhead watering favor outbreaks in home gardens and food forests. Causal agent: Claviceps purpurea. In regenerative gardens, prioritize sanitation, airflow, and unbroken soil cover over calendar spraying, and intervene early when symptoms appear.
Symptoms
Dark purple-black, elongated sclerotia (ergot bodies) replacing individual grain kernels. Honeydew (sticky, sweet exudate) on flower heads during infection. Sclerotia are larger than normal kernels and protrude from the head. Compare several plants and note whether symptoms spread after rain, insect feeding, or wet foliage. Photograph undersides of leaves and cut stems when wilt is present to refine the diagnosis. Rule out simple drought, fertilizer burn, and herbicide drift before assuming a pathogen - abiotic injury often mimics disease.
Environmental Conditions
Cool
Prevention
Plant certified clean seed. Rotate crops. Mow field margins to reduce grass hosts. Deep plow to bury sclerotia. Plant varieties with short, uniform flowering periods. Mulch to reduce splash, clear season-end debris, and avoid working plants when wet. Design beds for airflow and diverse plantings that support beneficial insects without creating permanent humid pockets around susceptible crops.
Management
Clean seed to remove sclerotia. Deep plowing to bury sclerotia below germination depth. Crop rotation. Mow grass borders before flowering. Fungicide application during flowering in severe cases. Prefer drip irrigation, morning watering, and open spacing so leaves dry quickly. Disinfect pruners between cuts on woody plants. Use copper, sulfur, or biological products only as labeled protectants when pressure is high - they rarely reverse advanced infections alone. Destroy (do not casually compost) highly infectious debris.