The Ecology, Population Dynamics and Management of Saffron Thistle (Carthamus lanatus) in Eastern Australian Pastures
Project Update
This project was completed in 2000.
In September 1999 Blair Grace went to southern France to compare the ecology of saffron thistle in France (where the thistle occurs naturally but is rarely a problem) with its ecology in Australia, where it is a significant weed. He found that ants in Europe removed many seeds before they can germinate, and this does not happen in Australia. Other findings were that European thistles (chárdon) were commonly attacked by stem boring insects, which are not present in Australia. Biological control using some of these insects is therefore worth investigating.
On the same trip, Blair also attended the European Weed Research Society Conference in Basel, Switzerland. This trip was funded by the CRC for Weed Management Systems.
Project Summary
Saffron thistle (Carthamus lanatus) is Australia's most abundant thistle, and costs around $111 million each year. Surprisingly, precious little is known about how the weed behaves in eastern Australian pastures.
The key questions to be answered if the weed is to be effectively managed are:
- When does it germinate, flower and set seed, and how much seed is produced?
- Is seedling emergence and survival affected by competition with pasture or other saffron thistle plants?
- What stage of the life cycle has the highest mortality, and can this be influenced by grazing management?
- How quickly does the seedbank decline if the weed is controlled?
Germination is affected by rainfall, temperature and pasture cover. Inter and intra-specific competition reduces seedling survival. The time of flowering and seed production depends on rainfall. Larger rosettes and bolting plants are killed by sheep grazing.
Saffron thistle rosette |
Old Saffron thistle |
Researchers
B.S. Grace
B.M. Sindel
A.W. Sheppard
R.D.B. Whalley
Project Support
The project was based at the Agronomy and Soil Science Division, University of New England, Armidale, NSW. Funding for the research was provided by the Cooperative Research Centre for Weed Management Systems.