Eyespot of cereals

The pathogen Pseudocercosoporella herpotrichoides (also known as Oculimacula yallundae) is the causal agent of eyespot, a severe fungal disease affecting the stem base of cereal crops. This pathogen belongs to the division Ascomycota and is a major concern for wheat, barley, and rye growers worldwide.

The disease primarily infects the basal parts of the stems, creating characteristic eye-shaped lesions. These spots can coalesce, leading to severe decay of the culm tissues. This structural damage weakens the plant, significantly increasing the risk of lodging, which is the most noticeable field symptom, often resulting in messy, uneven crop stands.

The life cycle of the fungus is highly dependent on humidity and temperature. It survives as mycelium on crop debris. In cool, wet autumns and springs, the fungus produces conidia, which are splashed by rain onto the stems of developing seedlings. The disease cycle is favored by temperatures ranging from 5°C to 15°C and persistent moisture at the soil-plant interface.

The economic impact is substantial due to yield loss and reduced grain quality. By interrupting the water and nutrient transport through the stem, the fungus prevents proper grain filling, leading to shriveled grains and lower thousand-kernel weight. Severe outbreaks can reduce yields by up to 30%, especially in continuous cereal production systems.

Management strategies focus on cultural practices and targeted fungicide applications. Implementing a crop rotation with non-host species is the most effective way to break the disease cycle. Additionally, selecting resistant varieties and avoiding early sowing dates can significantly reduce initial infection rates. Chemical control should be timed according to crop growth stages, usually during early spring tillering.

• Implement a minimum 2-year break in cereal rotation.
• Select crop varieties with high genetic resistance.
• Manage crop residues through proper soil cultivation.
• Apply systemic fungicides during the early stem elongation stage.