Eyespot (wheat)

Eyespot is an important fungal disease of wheat caused by the necrotrophic fungus Tapesia yallundae (syn: Pseudocercosporella herpotrichoides; W-type [anamorph]; Oculimacula yallundae) and Tapesia acuformis (syn: Pseudocercosporella herpotrichoides; R-type [anamorph]; Oculimacula acuformis).

[1] The eye-shaped elliptical lesions which give eyespot its name form on lower stem bases near to the soil surface.

The lesions are straw yellow, often with black pupil-like dots in the centre, and are bordered by greenish-brown to dark-brown rings.

Alternatively in other cases of severe infection the nutrient and water supply to the plant is disturbed, resulting in low quality grain and whitehead production due to early maturation.

Invasion of Pseudocercosporella herpotrichoides in wheat initiates with release of enzyme for breaking the plant cell wall.

The plant starts forming the papillae - a callose matrix (cellulose, suberin, protein, gums, calcium and silicon) which provides extra resistance to penetration, however this barrier does remain effective for long if the level of micro-organisms present is high.