Toxic endophyte-infected tall fescue and range grasses: historic perspectives.

Abstract

A historic profile of endophyte-induced tall fescue toxicosis is presented. A chronology of events is presented, beginning with the importance of finding Balansia-infected grasses in a tall fescue pasture in north central Georgia. This initial finding was followed by the discovery that another related endophyte was present in tall fescue and other major forage grasses. This species of endophyte was identified as Acremonium coenophialum. After this report was the important discovery that cattle performance was poor on Acremonium-infected tall fescue. Thus, this endophyte and its presence in tall fescue was implicated as the cause of tall fescue toxicosis and fescue foot. It was later established that this endophyte also produced ergot alkaloids. The related endophyte of perennial ryegrass, A. lolii, was subsequently shown to be responsible for the ryegrass staggers syndrome. Several other species of Acremonium have been associated with other important forage and turf grasses. Finally, important papers leading to the revelations that endophytic fungi and their grass hosts are ecologically significant and that most should be considered mutualistic symbioses are reviewed. Symbiotic grasses have enhanced physiological and morphological characteristics that offer biotechnological exploitations on one hand, but on the other solutions to the toxicity of tall fescue are difficult because grasses free of their fungal partner are generally ecological failures.