Transcript Document

Grassy weeds in pastoral systems
- CONTEXT, NEEDS AND DIRECTIONS
• weeds are everywhere
• pastoral systems are often weedy
• perception is important
Weeds of pastoral systems
• Weeds of significance to the grazing industries of Australia
MLA and Weeds CRC 2002
• 119 weed species referenced
• 48 species or groups of species of greatest significance
• 9 grasses or groups of grasses:
African lovegrass
browntop bent grass
Chilean needle grass
Coolatai grass
grader grass
annual grasses – e.g. barley grass
perennial mission grass
rat’s tail grasses
serrated tussock
Grassy weeds – where have they come from?
INTRODUCED GRASSES
DELIBERATE
AGRICULTURE
ACCIDENTAL
ORNAMENTAL
Grassy weeds – where have they come from?
CSIRO Plant Introduction Service 1924-2000
crops
197 species
other C3 grasses
1067
other C4 grasses
992
TOTAL
2250
No. of grass accessions introduced from
Sub-Saharan Africa
3490
Asia
2052
N&E Europe
3786
Mediterranean
2934
North America
4559
Central America
298
South America
2000
Other/unknown
660
TOTAL
19779
Some deliberately introduced weedy grasses
Pennisetum – 5 species
including P. polystachion (mission grass)
Nassella – 9 species,
including N. trichotoma and N. neesiana
Andropogon virginicus
Bromus 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
•
Weeds CRC in its second round since 2001
•
3 research programs
(1) Management of new incursions
(2) Cropping systems
(3) Landscape management
•
Landscape Management Program
Task 1: Habitat approach
Task 2: Functional group approach
Task 3: The science of biological control
•
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