WEED WEDNESDAY: Serrated tussock (Nasella trichotoma)

08th Mar 2023

WHAT'S THE IMPACT?

Serrated Tussock is a drought tolerant grass with low feed value. It takes over pastures and native vegetation and is not palatable to stock. Animals grazing on it become malnourished. Serrated Tussock can contaminate hay and grain.

HOW DO I IDENTIFY IT?

Leaves are:

- whitish at the base, looking like shallots

- tightly rolled, narrow and stiff

- upright

- serrated, felt when drawing the leaf between your fingers

Seedheads are:

- on a spike that leans over

- clustered in a group up to 35cm long

- branched with a single flower on each branch

- wrapped in red/brown bracts

Seeds are:

- in a seed head on the flower spike

- golden brown

- hard and small, 1.5mm long

- with a ring of white hairs where they connect to the plant

- with an awn 25mm long, offset from the centre at the other end

Roots are:

- deep

- fibrous

- difficult to pull out of the ground even when plants are small

HOW DOES IT SPREAD?

Serrated Tussock seeds can spread long distances by wind and water. Ripe seed heads break at the base and are carried long distances by wind 10 km or more if conditions are favourable. Seeds also spread by feed, animals and machinery. Animals can pick up seeds in hooves, fleeces or coats. Serrated Tussock seeds remain viable even after passing through an animal’s gut.