The role of Penicillia in ryegrass staggers.

Tremorgenic strains of Penicillium verrucosum var cyclopium, P canescens, P janthinellum, P novaezeelandiae and P estinogenum were isolated from the faeces of 15 of 23 affected sheep and cattle in eight of nine field outbreaks of ryegrass staggers. One tremorgenic strain of P griseofulvum was isolated from the faeces of one of 25 sheep grazing in unaffected flocks. Tremorgenic strains of P verrucosum var cyclopium, P canescens, P janthinellum and P estinogenum were also isolated from the A horizon of New Zealand soils. Since a large proportion of experimentally dosed live P verrucosum var cyclopium died during passage through the gut, the faecal evidence from naturally staggering animals suggests that at least some outbreaks of ryegrass staggers are caused by tremorgenic Penicillia and that their source may be soil.