Leaf Spot — Sheep's Fescue

Sheep's fescue is characteristically susceptible to dollar spot disease, caused by Sclerotinia homoeocarpa, as well as infection by pathogens of the genus Fusarium, such as F. culmorum, F. equiseti, and F. oxysporum, which induce the appearance of necrotic spots on leaf sheaths.

The clinical presentation manifests as general chlorosis of the leaves with the development of yellow, brown, or purple hues, spot formation, and subsequent desiccation of the leaf apparatus. The development of these symptoms often occurs under adverse environmental conditions, such as high humidity and insufficient soil aeration.

The defense mechanisms of sheep's fescue are largely associated with symbiosis with endophytes of the genus Epichloë, which provide resistance through the production of metabolites that inhibit infection or by the physical exclusion of pathogens from plant tissues.