This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

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Cropping systems were: corn + atrazine + EPTC/dichlormid; corn + atrazine + metolachlor; corn + atrazine + bentazon; corn + EPTC/dichlormid intercropped with red clover as green manure or managed as forage crop in the following year; alfalfa + EPTC; soybean + metalachlor + metribuzin; sorghum as green manure followed by winter wheat; and spring barley + diclofop-methyl + bromoxynil. Control treatments were yellow nutsedge growing in a pure stand and complete yellow nutsedge control. After two growing seasons in experiment #1, the tuber population had decreased in all cropping systems. Yellow nutsedge was reduced to 9% of the initial population under perfect control while it tripled in the pure stand. After the first growing season in the second experiment, only corn intercropped with red clover significantly reduced yellow nutsedge population by 17%. When the systems were not treated with herbicides, the yellow nutsedge population increased between 41 to 180% in all cropping systems. There was a significant relation between yellow nutsedge, broadleaf weed and grass densities and yellow nutsedge tuber production. Corn was the most profitable cropping system. The least economically advantageous cropping system was barley.

Mechanical weeders were tested on both mineral and organic soils in 1995 and in 1996, to measure their impact on soil physical properties. The weeders were tested in three crops, carrots in mineral and organic soil, beans in mineral soil, and lettuce in organic soil. Soil bulk density and water content were measured at regular intervals during the weeder trial period, and samples for soil structural analysis were collected in the mineral soil at the beginning and at the end of each season. / No significant results were found in differences in mean weight diameters of dry and water-stable aggregates. Soil moisture did not vary significantly due to treatment. There was significant compaction caused by the first pass in the field (i.e., seeder) in all the crops at both sites in the 0--10 cm layer, and in some cases, to a depth of 25 cm. Additional field passes with the weeders caused some compaction in the tractor wheel at the 0--10 cm depth, and sometimes in the 10--25 cm layer, in all trials in mineral soil, yet no significant effects of treatments were detected in the trials at the organic soil site. No conclusions could be drawn as to the benefits and/or negative impacts of mechanical versus chemical weeding in mineral soil, with respect to the relative compaction caused by the mechanical weeders. This is because in this experiment spraying of herbicides did not involve tractor traffic in the field.

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Field experiments were conducted from 1989 to 1991 to evaluate several sulfonylurea herbicides, glyphosate and clopyralid for the control of bunchberry and other hexazinone tolerant weeds in lowbush blueberry. Broadcast applications of chlorosulfuron, metsulfuron and glyphosate reduced bunchberry densities at all application dates, though crop damage and subsequent yield reductions were unacceptable. Glyphosate was very effective in controlling a large number of plant species when applied as a spot spray treatment. Tribenuron and DPX R9674 were effective in suppressing bunchberry stem densities at all application dates, without major adverse effects on blueberry, and also controlled a large number of hexazinone tolerant weeds when applied as a spot spray treatment. Clopyralid, at rates as low as 100 g a.i. ha$ sp{-1}$, was very effective as a broadcast treatment for the control of tufted vetch, although problems with crop tolerance and yield reductions were evident in some instances. Clopyralid did not control a large number of hexazinone tolerant species when applied as a spot spray treatment.

Title page, table of contents and abstract only. The complete thesis in print form is available from the University of Adelaide Library. / Field experiments investigating the nature and extent of interference in monocultures and mixtures of wild radish and wheat were conducted in 2003 and 2004 at Roseworthy, South Australia. Intraspecific and interspecific interfenernce between wild radish and wheat was investigated in the field using additive series design. Results indicated that higher densities of wheat were able to suppress seed production of this weed species. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1274618 / Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2006

This study of some common turf weeds of the Vancouver area considers some aspects of biology and control. Seed production observations indicated that seeds ranging from 300 to over 260,000 per plant were produced each season by different species. Seeds of Senecio vulgaris L., Sonchus oleraceus L. and Hypochaeris radicata L. germinated immediately after harvest while others required several months. H. radicata showed good germination in light while Cerastium vulgatum L. and Lamium amplexicaule L. germinated best in a shaded or dark environment. Two germination peaks in spring and fall occur in this group of turf weeds. However Stellaria media (L.) Cyrill produced flowers and seed for most of the year. Rumex acetosella L. also had a long flowering period as did Plantago lanceolata L. and P. major L. The three latter species were found to require a long time to mature in the flower head and so were not shedding seed over the considerable period of time characteristic of S. media. Leaf area development did not appear to be associated with root development in the seedling weeds examined, and variations in the relative leaf areas of the different species occurred with time. Marked differences in flowering period and characteristics were apparent in observations on the various weeds made over a 17 month period. Apomictic seeds of Taraxacum officinale L. were found to have a germination rate significantly lower than those produced by artificial pollination. Inhibitory materials present in leaves and stems of weeds were shown to delay germination of bent grass nearly three weeks and to definitely reduce the percentage germination. The species showing the greatest inhibitory properties were Matricaria matricarioides (Less.) Porter, S. media and P. lanceolata in that order. Four turf grasses were shown to differ in their responses to proprietory mixtures of the phenoxy type herbicides, and weed species similarly differed in their responses to the newer herbicides which included Banvel D (dicamba), Tordon, phenoxypropionic materials and mixtures containing two and three chemicals. / Land and Food Systems, Faculty of / Graduate

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the academic requirements for the degree of Doctor of Philosophy School of Animal, Plant and Environmental Sciences. Johannesburg, June 2018. / Lantana camara L. (sensu lato) (Verbenaceae) remains one of the worst invasive alien plants in most tropical and subtropical parts of the world, including South Africa. Despite a concerted biological control (biocontrol) effort, with 45 biocontrol agents released against the weed worldwide since the early 1900s to date, L. camara control is far from satisfactory in most areas, including the study area. In 2012, during the initial stage of this work, a plant-ecological survey was conducted in riparian areas along the Sabie River, across an altitudinal gradient, and also in the adjacent forest plantation areas, in the province of Mpumalanga (South Africa). As a follow-up to two separate previous studies in the same area (1996/7 and 2005), aimed at determining the effectiveness of the ‘Working for Water’s (WfW) invasive alien plant (IAP) control programme, this work is another milestone in a long-term monitoring study. However, despite 16 years (1996/7-2012) of integrated IAP-control operations in the area, the WfW programme was only able to successfully remove larger overstorey IAPs, which opened-up the canopy and reduced competition, creating a conducive growing environment for an amalgamation of understorey IAPs, including L. camara, whose spread and densification were still on the rise. Biocontrol is regarded as a better alternative for long-term, sustainable and environmentally friendly IAP control, compared to the conventional mechanical and chemical methods. Most L. camara biocontrol agents introduced into South Africa have not yet had their full impact quantified under field conditions. This work is novel in that, for the first time, it quantifies the combined impact of the ‘old plus new’ suite of L. camara biocontrol agents, on the growth, reproduction and biomass of the weed under field conditions, in an inland area, through an insecticidal exclusion experiment, using carbofuran. Five prominent biocontrol agents occur on L. camara at the study sites, namely the fruit-mining fly, Ophiomyia lantanae (Froggatt) (Diptera: Agromyzidae); the shoot-sucking bug, Teleonemia scrupulosa Stål (Hemiptera: Tingidae); the defoliating moth, Hypena laceratalis Walker (Lepidoptera: Noctuidae); the leaf-mining beetle, Octotoma scabripennis Guèrin-Mèneville (Coleoptera: Chrysomelidae); and the fungal leaf-spot pathogen, cf. Passalora sp. (Chupp) U. Braun & Crous var. lantanae. During the course of this study, an additional agent, the flower-galling mite, Aceria lantanae (Cook) (Acari: Trombidiformes: Eriophyidae), was released and successfully established at lower altitudes (~843 m), showing an affinity for the dark-pink L. camara variety over others in the study area, namely light-pink and red-orange. Agent impact was difficult to measure because the activity of carbofuran in exclusion plants (carbofuran-treated L. camara plants) was short-lived; and therefore the impact of biocontrol agents on L. camara, which appeared to be negligible, may have been underestimated. Despite failing to maintain the ‘exclusion’ plants biocontrol agent-free through the application of carbofuran, there were reductions of 28% in the number of side-stems per plant, 31% fewer seeds in the soil seedbank, and 29% lower seed production, in ‘biocontrol’ plants compared to ‘exclusion’ plants. Although these differences were not statistically significant, they suggest that the present suite of biocontrol agents slightly reduces the vegetative and reproductive growth of L. camara. To achieve significant biocontrol of L. camara in inland areas, it seems necessary to introduce additional agents, which are well adapted to inland climatic conditions. The effects of micro-environmental factors, namely altitude and the degree of shading, were also investigated. Some biocontrol agents, such as T. scrupulosa, exhibited feeding phenological plasticity, resulting in it maintaining its presence at different altitudinal levels throughout the seasons. The performance of the suite of biocontrol agents, except A. lantanae, was, also, not limited by plant varietal differences. Additional research on biological and integrated control of L. camara is required. Keywords: Biocontrol; Biological invasion; Carbofuran; Insecticidal exclusion; Invasive alien plants; Lantana camara; Post-release evaluation. / LG2018

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