Eyespot of cereals

The fungus Phaeosphaeria herpotrichoides is the causal agent of eyespot, a serious disease affecting the base of cereal stems. This pathogen belongs to the class of fungi responsible for foot rot diseases in small grains. It disrupts the vascular tissue of the lower stems, which significantly impairs water and nutrient uptake in the host plant.

Common host crops for this pathogen include winter wheat, winter rye, and barley. The disease is widespread in regions with temperate climates where cool, wet weather persists during the critical stages of early spring development. The fungus can survive for several years on infested crop debris, making it a persistent threat in continuous cropping systems.

The primary symptom is the formation of lens-shaped, elliptical lesions on the leaf sheaths and stems near the soil surface. These lesions typically feature a dark margin, resembling an eye, hence the name of the disease. As the fungus colonizes the inner stem tissues, the stem weakens, leading to severe lodging, stunted growth, and the development of empty or poorly filled heads.

Environmental conditions play a crucial role in the development and spread of Phaeosphaeria herpotrichoides. The infection is favored by high humidity and cool temperatures ranging from 5 to 15 degrees Celsius. Conidia produced on infected crop residues are splashed onto the lower parts of new plants by rain, leading to secondary cycles of infection if weather conditions remain conducive.

Eyespot can cause substantial yield losses, sometimes exceeding 30%, especially in severe outbreaks where lodging prevents proper mechanical harvesting. Effective management relies on an integrated approach:

• Implementing crop rotation with at least a two-year break for cereals.
• Planting resistant or tolerant cultivars.
• Optimizing sowing dates to avoid early autumn infection.
• Strategic application of fungicides during the tillering stage if disease thresholds are met.