Grassy weeds in pastoral systems

- CONTEXT, NEEDS AND DIRECTIONS

• weeds are everywhere

• perception is important

• pastoral systems are often weedy

Weeds of pastoral systems

• Weeds of significance to the grazing industries of AustraliaMLA and Weeds CRC 2002

• 119 weed species referenced

• 48 species or groups of species of greatest significance

• 9 grasses or groups of grasses:African lovegrassbrowntop bent grassChilean needle grassCoolatai grassgrader grassannual grasses – e.g. barley grassperennial mission grassrat’s tail grassesserrated tussock

Grassy weeds – where have they come from?

INTRODUCED GRASSES

DELIBERATE ACCIDENTAL

ORNAMENTALAGRICULTURE

Grassy weeds – where have they come from?

CSIRO Plant Introduction Service 1924-2000crops 197 speciesother C3 grasses 1067other C4 grasses 992TOTAL 2250

No. of grass accessions introduced fromSub-Saharan Africa 3490Asia 2052N&E Europe 3786Mediterranean 2934North America 4559Central America 298South America 2000Other/unknown 660TOTAL 19779

Some deliberately introduced weedy grasses

Pennisetum – 5 speciesincluding P. polystachion (mission grass)

Nassella – 9 species, including N. trichotoma and N. neesiana

Andropogon virginicusBromus spp.Eragrostis curvula (African lovegrass)Hyparrhenia hirta (Coolatai grass)Sporobolus indicus (rat’s tail grass)Themeda quadrivalvis (grader grass)Vulpia bromoides

Weedy grasses and the Weeds CRC

• Landscape Management ProgramTask 1: Habitat approach Task 2: Functional group approachTask 3: The science of biological control

• Weeds CRC in its second round since 2001

• 3 research programs(1) Management of new incursions(2) Cropping systems(3) Landscape management

• Task 3 deals with four functional groups(i) invasive rangeland shrubs(ii) bird-dispersed weeds(iii) aquatic weeds(iv) unpalatable grasses

Unpalatable grass weeds in context

• Prominence

• Impact

• Threat

• Intractability

• Conflict