Spreading cornmeal on soil or lawns cures fungal disease.
Don't use cornmeal as a fungicide. The idea comes from beneficial fungi that grow on it, but cornmeal itself feeds many fungi, pathogens included, and no published research backs it. Manage fungal problems with good drainage, sensible watering and airflow. Don't confuse it with corn gluten meal, a separate weed product.
What is actually known
This traces to a real observation. Trichoderma and other fungi that attack plant pathogens grow vigorously on cornmeal, and it is those fungi that do the suppressing. Cornmeal itself is no fungicide. It feeds many fungi (labs use it to culture pathogens such as Rhizoctonia), and no published research supports using it for this or any other garden purpose. (Don't confuse it with corn gluten meal, a different product sold as a pre-emergent weed suppressant, whose real-world results have been inconsistent.) What actually limits fungal disease in a lawn is the setup: good drainage, no overwatering, and air movement.
The evidence
Evidence: checked against 2 sources in the research-based literature.
The 2 sources
Further work identified Trichoderma spp. as one of these antagonistic fungal groups (Gul and Fazli 2005) that grow vigorously on cornmeal agar
Poor soil drainage, lack of air movement, shade, cloudy weather, dew, over-watering, and watering in late afternoon favor prolonged leaf wetness and increased disease severity.
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Cite this page
Milpa Gardens. "Spreading cornmeal on soil or lawns cures fungal disease." Evidence grade: Refuted. https://milpa.garden/beliefs/cornmeal-fungicide-cornmeal-lawn/
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