Oculimacula acuformis

Systematic position and nature of the pathogen. Oculimacula acuformis is a fungus belonging to the kingdom Fungi, phylum Ascomycota. It is a well-known plant pathogen responsible for causing eyespot disease in various cereal crops. Historically known as a variant of Pseudocercosporella herpotrichoides, this fungus is specifically associated with the weakening of the stem base in small-grain cereals.

Diseases and host crops. The fungus primarily causes eyespot, a serious fungal disease that affects winter wheat, barley, and rye. The infection is characterized by the formation of lesions on the leaf sheaths and the first internodes of the stem. These lesions often look like eyes, with a pale center and a dark brown border, which can cause severe stem lodging.

Biology and lifecycle. The pathogen overwinters as mycelium and stroma in crop residues on the soil surface. During cool, wet conditions in the autumn and spring, it produces spores (conidia) that splash onto the base of the stems. The fungus gradually colonizes the outer tissue, penetrating inward and disrupting the vascular system of the plant as the season progresses.

Development conditions and impact. Development is favored by high humidity and temperatures between 5°C and 15°C. Wet winters and early springs significantly increase the risk of an epidemic. The economic impact is substantial: plants with weakened stems are prone to lodging, leading to poor grain filling, reduced kernel weight, and potential yield losses of up to 30% in highly infested fields.

Control measures and management. Controlling Oculimacula acuformis requires an integrated approach focusing on cultural and chemical practices:

• Implementation of crop rotation to reduce inoculum build-up.
• Deep plowing to bury infected stubble and promote decomposition.
• Selection of resistant or tolerant cereal cultivars.
• Timely application of targeted fungicides during the early tillering stage.