Dispersal and genetic variability of Sonchus oleraceus L. in relation to its resistance to ALS-inhibiting herbicides.

The work described in this thesis investigates the existence and level of acetolactate synthase (ALS)-inhibiting herbicide resistance in Sonchus oleraceus in Australia. It further discusses the sensitivity of different S. oleraceus populations to different dose rate treatments of the ALS-inhibiting herbicide, chlorsulfuron. Thirdly the movement or not of the resistance gene between S. oleraceus plants. Gene movement is investigated in light of S. oleraceus being self pollinated and possessing a wind dispersed seed. Finally using molecular tools the genetic diversity and seed movement in S. oleraceus is investigated. Although much is known about the evolution of plant based genetic resistance to herbicides there is less known as to the specific resistance gene movement in differing weed species. The first approach undertaken in this study was to collect a broad spectrum of S. oleraceus seed from a number of Australian states and test the progeny from this seed for resistance to chlorsulfuron. Subsequent to this DNA extractions were made from S. oleraceus plant material for use in AFLP and sequencing techniques. The results of this study indicate that ALS-inhibiting herbicide resistance to chlorsulfuron in S. oleraceus is now widespread in Australia. The movement of the resistance gene within populations is low (<4%), however, population dendrograms indicate seed has been dispersed across large distances in Australia facilitating the movement of the resistance gene. In addition sequence analysis indicates numerous independent mutation events. With the identification of previously unknown levels of resistance in Australia and gene movement knowledge, extension of improved management practises is possible.Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 201

The biology and ecology of rampion mignonette Reseda phyteuma L.

Rampion mignonette is an annual to short-lived perennial agricultural weed from the Mediterranean region, first found in vineyards at Clare, South Australia, in 1986. The biology and ecology of rampion mignonette was studied to provide a basis for its integrated control and management. The study includes a literature review, maps of world and Australian distribution and drawings showing plant habit and details. A field survey found that rampion mignonette showed little migration and that containment and population reduction could be achieved by careful management including both chemical and cultural techniques. Common herbicides were also found to be effective in controlling the weed. An experiment established that it is unlikely to become a major weed of broadacre crops and pastures in the South Australian dryland farming system. It does however have the potential to compete with grapevines and reduce grape yields.Thesis (M.App.Sc.)--University of Adelaide, Dept. of Agronomy and Farming Systems, 199