Bibliography: leaves 124-136. This thesis gives an overview of factors used in weed risk assessments and explores the disparity between the measured high accuracy rate of the weed risk assessment system (WRA) as implemented in Australia and the pessimistic assessments of some workers about the possibility of predicting the weed potential of plant species imported in the future. The accuracy of the WRA may not be as high as previously thought, and it varies with weed definition and taxonomic groups. Cluster analysis and comparative analysis by independent contrasts were employed to determine the value of individual biological and ecological questions on the WRA questionnaire. Results showed that some WRA questions could be deleted from the questionnaire and the scores for others weighted differently. The WRA is not a reliable predictor of weeds when it is considered in the context of the base-rate probability of an introduced plant becoming weedy in Australia. As a result a far greater number on non-weeds will be placed on the prohibited imported list than was initially expected.

Bibliography: leaves 82-89. 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.

Bibliography: leaves 147-163. / ix, 164 leaves : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The aim of this thesis is to confirm the resistance status of three purported resistant weed species by herbicide screening of outdoor pot grown plants. Field experiments are set up to investigate changes in dormancy and seedbank life of the resistant populations over a three year period. After determining the herbicide resistance spectrum of the resistant biotypes, genetic crosses between resistant and susceptible plants are performed to follow the mode of inheritance of acetolactate synthase (ALS) resistance. "In vitro" ALS enzyme assays in the presence of various herbicides are carried out to reveal a modified ALS enzyme as the main mechanism of resistance in all cases. A molecular investigation of the ALS gene is performed to identify mutations responsible for endowing a resistant enzyme. / Thesis (Ph.D.)--University of Adelaide, Dept. of Crop Protection, 1996

186 p. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.) University of Adelaide, Dept. of Agronomy, 1989

Bibliography: leaves 147-163. / ix, 164 leaves : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The aim of this thesis is to confirm the resistance status of three purported resistant weed species by herbicide screening of outdoor pot grown plants. Field experiments are set up to investigate changes in dormancy and seedbank life of the resistant populations over a three year period. After determining the herbicide resistance spectrum of the resistant biotypes, genetic crosses between resistant and susceptible plants are performed to follow the mode of inheritance of acetolactate synthase (ALS) resistance. "In vitro" ALS enzyme assays in the presence of various herbicides are carried out to reveal a modified ALS enzyme as the main mechanism of resistance in all cases. A molecular investigation of the ALS gene is performed to identify mutations responsible for endowing a resistant enzyme. / Thesis (Ph.D.)--University of Adelaide, Dept. of Crop Protection, 1996