Ceratobasidium gramineum

Ceratobasidium gramineum, often associated with its anamorph Rhizoctonia cerealis, is a significant fungal pathogen affecting a wide range of cereal crops. It is known to cause sharp eyespot and other root-related diseases that can substantially reduce plant vigor and crop yields in temperate climatic zones.

The disease primarily targets wheat, barley, oats, and rye, although it can infect various grass species. The pathogen colonizes the lower stems and root tissues, interfering with the plant's ability to transport water and nutrients efficiently from the soil to the grain-filling parts of the plant.

Symptoms are usually identified by the presence of distinct lesions on the leaf sheaths and stem bases. These lesions are typically elliptical with light centers and dark brown margins, resembling "eyes." In severe cases, the stem tissue becomes weakened, leading to premature ripening, lodging, and reduced grain weight.

The fungus thrives in cool, moist conditions with temperatures ideally between 10°C and 20°C. High humidity at the soil surface and poor drainage are primary contributors to the disease's spread. The pathogen persists in the soil via sclerotia or within colonized crop residues from previous seasons.

Management and prevention strategies focus on limiting the pathogen's development through field management:

• Crop rotation with non-host plants to break the disease cycle.
• Treatment of seeds with systemic fungicides to protect seedlings during germination.
• Improving soil drainage to prevent excessive surface moisture.
• Maintaining optimal plant density to encourage airflow and reduce canopy humidity.