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
