Pathogens On and Variation in Nassella trichotoma

Serrated tussock (Nassella trichotoma (Nees) Hack. ex Arechav.)) is arguably the most important pasture weed in south-eastern Australia. For biological control, pathogens that are effective on all populations are needed. Two fungi, Dinemasporium sp. Léveillé and Ascochyta sp. Lib., form leaf spots asso-ciated with death of serrated tussock north-west of Melbourne. Inoculation with spore sus-pensions from culture reduced germination. Inoculation of seedlings with Dinemasporium sp. resulted in infection and necrosis in pot experiments. Germination was also reduced by an unknown white fungus and Fusarium sp. Link ex Fries isolated from abundant external white mycelium on the base of the culms and associated with root rot. These fungi have potential for biological control of serrated tussock in Australia