Bibliography: leaves 209-254. Experiments detailed in this thesis, evaluate the impact of various herbicides and herbicide mixtures on the growth, nodulation and nitrogen fixation of annual pasture legumes, the efficacy of the herbicides for weed control, and the potential role of mechanical defoliation to replace herbicides, leading to lower cost and more sustainable farming systems.

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.

<p>Weed control is nowadays a hi-tech discipline. Inter-row weed control is very sophisticated </p><p>whereas the intra-row weed control lacks a lot. The aim of this pro ject is to implement </p><p>an embedded system of an autonomous vision based intra-row weeding robot. Weed and </p><p>crops can be distinguished due to several attributes like colour, shape and context fea- </p><p>tures. Using an emebedded system has several advantages. The embedded system is </p><p>specialized on video processing and is designed to withstand the needs of outdoor use. </p><p>This embedded system is already able to distinguish between weed and crops. The per- </p><p>formance of the hardware is very good whereas the software still needs some optimizations.</p>

<p>In this study I investigate the sensitiveness of Bishop's goutweed (Aegopodium podagraria L.)to mechanical damages in an experiment with artificial clipping. Based on personalobservations of A. podagraria during several years I hypothesise that i) A. podagraria indifference with other species, for example different species of grass have difficult to recoverfrom mechanical damages ii) in a site with several other species present A. podagraria willhave harder to recover from mechanical damages than in a pure stand iii) as purer a stand withA. podagraria is, the harder other species will have to establish after the removal of aboveground parts of A. podagraria. The main conclusion of this work is that mechanical damagehas a significant effect on the vegetation cover of A. podagraria. The experiment also provethat a high grade of monoculture favours the ability of A. podagraria to recover frommechanical damage. It could however not be proven that high grade of monoculture of A.podagraria puts constraints on the ability of other species to establish on plots where A.podagraria is removed.</p>

Jointed goatgrass (Aegilops cylindrica Host; 2n=4x=28; CCDD) is an agriculturally important species both as a weed and as a genetic resource for wheat (Triticum aestivum L.; 2n=6x=42; AABBDD) improvement. In order to better understand the evolution of this species, the diversity of Ae. cylindrica was evaluated along with its progenitors, Ae. markgrafii (Greuter) Hammer (2n=2x=14; CC) and Ae. tauschii Coss. (2n=2x=14; DD), using chloroplast and nuclear microsatellite markers. Ae. cylindrica had lower levels of plastome and nuclear diversity than its progenitors. The plastome diversity of Ae. cylindrica was lower than its nuclear diversity. Ae. cylindrica was found to have either C-or D-type plastomes, derived from Ae. markgrafii or Ae. tauschii, respectively, where the C-type plastome was found to occur at a lower frequency than the D-type plastome. The nuclear genomes of Ae. cylindrica accessions with C-or D-type plastome were found to be very closely related, suggesting a monotypic origin. Furthermore, analyses suggests that Ae. tauschii ssp. tauschii contributed its D genome and D-type plastome to Ae. cylindrica. Ae. cylindrica accessions collected near Van Lake in southeastern Turkey, an area where Ae. tauschii ssp. tauschii and Ae. markgrafii overlap, showed high allelic diversity and may represent the site where Ae. cylindrica formed. Population structure analyses suggested a lack of regional genetic structure in Ae. cylindrica and evidence of migration of Ae. cylindrica among various regions. Finally, Ae. cylindrica accessions in the USA were found to be closely related to accessions from at least three regions of its native range central Anatolia, central East Turkey and western Armenia, and Caucasia. Wheat and jointed goatgrass are closely related and both have the D-genome. These two species can hybridize and produce backcross derivatives under natural conditions, a situation that may allow gene flow between these two species. In order to better understand mating patterns between these two species, a total of 413 first-generation backcross (BC₁) seeds obtained from 127 wheat-jointed goatgrass F₁ hybrids, produced under natural conditions, were evaluated for their parentage using chloroplast and nuclear microsatellite markers. Of the 127 F₁ hybrids evaluated, 109 had jointed goatgrass as the female parent, while the remaining 18 F₁ plants had wheat as the female parent. Of the 413 BC₁ plants analyzed, 358 had wheat and 24 had jointed goatgrass as the recurrent male parent. The male parentage of 31 BC₁ plants could not be determined. Although the majority of hybrids were pollinated by wheat, backcrossing of hybrids to jointed goatgrass would enable gene flow from wheat to jointed goatgrass. Though the observed frequency of jointed goatgrass-backcrossed hybrids (F₁ X jointed goatgrass) was low under field conditions, their absolute number is dependent on frequency of hybrids, which in turn, depends on the density of jointed goatgrass in wheat fields. Therefore, the recommendations to control jointed goatgrass in wheat fields and adjacent areas and to plant jointed goatgrass free wheat seed should be followed in order to avoid gene flow from wheat to jointed goatgrass. / Graduation date: 2006

Flax (Linum usitatissimum L.) is considered as a model plant species for multipurpose uses with whole plant utilization for several purposes including industril, food, animal feed, fiber, nutraceutical, pharmaceutical, and bioproduct markets. Therefore, flax is in the process of genetic engineering to meet the market requirements. Prior to commercial release of genetically engineered (GE) flax, a risk assessment was conducted to determine intra- and inter-specific pollen-mediated gene flow and for quantifing and mitigating the adventitious presence (AP) of volunteer flax in canola (Brassica napus L.). The results of pollen-mediated gene flow study (crop-to-crop) suggest that about 1.85% outcrossing would occur in adjunct area, when two flax cultivars were grown in close proximity of 0.1 m apart. Some rare gene flow events were recorded maximum up to 35 m distance from the pollen source but at a very low frequency. The genus Linum has several wild and weedy species, distributed in many parts of the world. A meta-analysis was conducted to determine the potential for gene introgression from GE flax to wild relatives, the occurrence, the phylogeny of flax wild relatives and reported interspecific hybridization. The results demonstrated that cultivated flax has ability to hybridize and form viable F1 plants with at least nine species of Linum; however, none of these species have been reported to occur in Canada. Hybridization of flax with many other wild relatives has either not been studied or reported. However, based on the evidence of reported work, gene flow from GE flax to wild or weedy relatives may occur elsewhere depending on species distribution, sympatry, concurrent flowering, ploidy level and sexual compatibility. The results of the experiments to mitigate the adventitious presence of flax volunteers in canola suggest that combinations of pre-plant followed by post-emergence herbicides were most effective for reducing volunteer flax density and AP in glufosinate-resistant canola. Post-emergence application of imazamox+imazethapyr, however, was not effective for controlling volunteer flax in imidazolinone-resistant canola. Best management practices were developed to mitigate transgene movement from GE flax to ensure co-existance of GE, conventional and organic flax without market harm. / Plant Science

In this study I investigate the sensitiveness of Bishop's goutweed (Aegopodium podagraria L.)to mechanical damages in an experiment with artificial clipping. Based on personalobservations of A. podagraria during several years I hypothesise that i) A. podagraria indifference with other species, for example different species of grass have difficult to recoverfrom mechanical damages ii) in a site with several other species present A. podagraria willhave harder to recover from mechanical damages than in a pure stand iii) as purer a stand withA. podagraria is, the harder other species will have to establish after the removal of aboveground parts of A. podagraria. The main conclusion of this work is that mechanical damagehas a significant effect on the vegetation cover of A. podagraria. The experiment also provethat a high grade of monoculture favours the ability of A. podagraria to recover frommechanical damage. It could however not be proven that high grade of monoculture of A.podagraria puts constraints on the ability of other species to establish on plots where A.podagraria is removed.

Weed control is nowadays a hi-tech discipline. Inter-row weed control is very sophisticated whereas the intra-row weed control lacks a lot. The aim of this pro ject is to implement an embedded system of an autonomous vision based intra-row weeding robot. Weed and crops can be distinguished due to several attributes like colour, shape and context fea- tures. Using an emebedded system has several advantages. The embedded system is specialized on video processing and is designed to withstand the needs of outdoor use. This embedded system is already able to distinguish between weed and crops. The per- formance of the hardware is very good whereas the software still needs some optimizations.

Der gezielte Einsatz von reduzierten Aufwandmengen herbizider Tankmischungen in Mais ein Beitrag zur Umsetzung des integrierten Pflanzenschutzes in der landwirtschaftlichen Praxis. Ergebnisse von Ringversuchen der Länder Brandenburg, Sachsen, Sachsen-Anhalt und Thüringen in den Jahren 2004 - 2006. Wie weit können die Aufwandmengen von praxisüblichen Tankmischungen reduziert werden, um einerseits noch eine ausreichende Breitenwirkung zu erzielen und andererseits aber auch die Unkrautarten zu ermitteln, bei denen bei einer Dosisverminderung ein deutlicher Wirkungsabfall zu verzeichnen ist? Im Rahmen des von der Politik geforderten Reduktionsprogramms chemischer Pflanzenschutz (BMELV 2004) steht auch bei der Unkrautbekämpfung im Mais die Frage nach dem unbedingt notwendigen Maß beim Einsatz der verschiedenen herbiziden Wirkstoffe.

Three isolates of Curvularia belonging to Curvularia tuberculata (isolates 93-020 and 93-022) and Curvularia oryzae (isolate 93-061) were obtained from diseased Cyperus difformis, Cyperus iria, and Fimbristylis miliacea, respectively, in the Philippines in 1993. Under greenhouse conditions, these fungal isolates caused high mortality and significant plant dry weight reduction in C. difformis, C. iria, and F. miliacea when sprayed at the rate of 1 x 108 spores/m3. Cross-pathogenicity of the isolates was demonstrated in three other sedge weed species. C. difformis, C. iria, and F. miliacea were killed but C. rotundus was resistant. Most of the thirteen rice varieties tested were resistant to the fungal isolates. The order of decreasing pathogenicity to rice was C. oryzae (93-061), C. tuberculata (93-020), and C. tuberculata (93-022). The infection process of C. tuberculata and C. oryzae was similar. Spore germination was polar for C. tuberculata and bipolar for C. oryzae. Germ tube growth was random and branching. Appressoria were formed preferentially over epidermal cell wall junctions on sedge hosts and over stomatal apertures in rice. Complex infection cushions were observed only on sedge hosts. Infection hyphae developed inter- and intracellularly, causing epidermal cell walls to separate and mesophyll cells to shrink and collapse. The vascular bundles were not invaded. Colonization of susceptible weeds was rapid and conidiophores emerged from the stomatal aperture between 96 to 120 hours post inoculation (HPI). Resistance to C. tuberculata and C. oryzae in C. rotundus and rice was expressed as a delay in appressorial formation, inhibition of fungal growth after penetration, and lack of sporulation.