Perennial ryegrass staggers

Nature

Perennial ryegrass staggers is poisoning by peramine, lolitrem B, and other toxins that are contained in perennial ryegrass (Lolium perenne), and produced by the endophyte fungus Epichloë festucae which can be present in all parts of the grass plant, but tends to be concentrated in the lower part of the leaf sheaths, the flower stalks and seeds. This condition can affect horses, cattle, sheep, farmed deer and llamas. It regularly occurs in New Zealand and is known spasmodically from Australia, North and South America, and Europe.

Source: Wikipedia

Type 
(G) Very specific problems