Eyespot disease

The fungus Pseudocercosporella herpotrichoides (now commonly referred to as Oculimacula yallundae and O. acuformis) is a destructive plant pathogen within the Ascomycota phylum. It is the causal agent of eyespot, a serious disease that impacts the base of stems in various cereal crops.

The pathogen primarily affects winter wheat, barley, rye, and triticale. It is characterized by the development of eye-shaped lesions on the leaf sheaths and internodes at the base of the plant. As the infection progresses, it degrades the structural integrity of the stem, leading to typical stem breakage and significant lodging.

The biological cycle involves the fungus surviving in crop debris and soil as mycelium. Under cool, humid conditions, conidia are produced and spread by rain splash onto young plants. The infection migrates from the base of the leaves towards the tiller node, slowly colonizing the cortical tissues during the autumn and spring months.

Development and spread are strongly favored by mild, wet weather with temperatures ranging from 5°C to 15°C. Dense sowing and continuous cereal cropping create ideal conditions for the rapid multiplication of the pathogen, allowing it to persist in the field for several seasons if crop residues are not managed properly.

The economic impact is severe, resulting in shriveled grain, premature ripening, and large-scale lodging that hampers harvesting operations and reduces yield quality. Effective management strategies include:

• Utilizing resistant cereal varieties
• Implementing appropriate crop rotations
• Delaying autumn sowing to reduce initial infection
• Applying systemic fungicides at the early tillering stage