<p> California grows more than 91% of fresh strawberries in the United States. Critical to this success has been management of soilborne diseases using pre-plant soil fumigation with methyl bromide. However, international regulations require a phase out of methyl bromide, soon to be completed. Reduced availability of methyl bromide has coincided with increased incidence of soilborne diseases affecting strawberry production, including Verticillium wilt, caused by <i> Verticillium dahliae</i>, and Black Root Rot (BRR). BRR is caused by a complex of soilborne pathogens, including <i>Pythium ultimum</i>, that form lesions on tertiary roots, which are critical to nutrient and water uptake. Consequently, non-chemical alternatives for sustainable management of soilborne diseases and highly productive plants are urgently needed. </p><p> Crop rotation with legumes can contribute to plant productivity and disease management by fixing nitrogen and providing a non-host interval during which the pathogen can die by natural attrition. However, rotation crops that appear to be non-hosts because they show no symptoms of disease may nevertheless support development of the pathogen and thus negate the benefit of crop rotation. One objective of this research was to evaluate systemic colonization of ten legume cover crops <i>V. dahliae</i> under field conditions and the extent to which plant residue supports development of <i>V. dahliae </i> microsclerotia (Chapter 1). This included seven cool season legumes: broad 'Windsor' bean, bell bean, field pea, hairy vetch, common vetch, purple vetch and 'Lana' woolypod vetch, and three warm season legumes: sesbania, sunn hemp and black-eyed pea. Frequency of systemic infection at ten weeks ranged from 5% (woolypod vetch) to 23% (field pea) and at the end of the trial ranged from 0% (purple vetch) to 23% (hairy vetch). The trend for mean density of microsclerotia in residue at ten weeks ranged from 0 CFU/g residue (hairy vetch) to 583 CFU/g residue (field pea) and at the end of the trial ranged from 63 CFU/g residue (broad bean) to 1096 CFU/g residue (field pea). In most cases, frequency of infection and formation of microsclerotia in plant residue was higher by the end of the trial than at ten weeks. Thus, in fields infested with <i>V. dahliae</i>, growers should avoid rotation with the evaluated legumes to avoid increasing soil inoculum levels. </p><p> Compost can contribute to plant productivity and disease management by improving soil structure and fertility, and providing the necessary factors to shift soils from disease conducive to suppressive. This study was undertaken to evaluate four composts that are available to California strawberry growers: manure compost, spent mushroom compost, vermicompost and yard trimmings compost. The objective was to evaluate the effect on production parameters including soil quality and fertility, and plant growth and yield. Manure and mushroom compost significantly increased soil electrical conductivity, which reached levels of 9.9&plusmn;1.7dS/m and 7.3&plusmn;0.8dS/m, respectively. Manure, yard trimmings and mushroom composts shifted soil pH closer to optimal levels for up to 7 months in 4 to 5 of the trials. Mushroom compost had the greatest effect on soil nitrate, with up to 32 mg/kg nitrate higher than the non-amended soil. </p><p> Another potential benefit of compost is suppression of soilborne pathogens, which can result from changes in the composition and activity of the soil microbiota. It was an objective of this study to determine if four commercially available composts influence infection of strawberry roots by <i>V. dahliae </i> and <i>P. ultimum.</i> The results showed a significant reduction in <i>V. dahliae</i> root infections in some compost amended soils but results were not consistent across trials. The effect of compost amendments on seedling disease caused by <i>P. ultimum</i> was a reduction in disease incidence by 38-43% compared to the non-amended soil. </p><p> The industry-wide shift in strawberry production generates a tremendous need for knowledge transfer and grower support. Accordingly an additional objective of this research was to solicit industry perspectives on the status of soilborne disease management. Results identified crop rotation as the most important tool in the absence of fumigation as, reported by 46% of respondents. When given a choice of thirteen management tools, crop rotation also had the highest ranking by respondents as a practice always used/recommended. </p><p> Numerous soilborne disease management tools, like crop rotation and compost, sustain high yields and reduce disease incidence, but vary in status of adoption. At a pivotal time when land is still productive but pathogens are becoming more widespread, a regional plan for maintaining pathogen-free soil has an opportunity to emerge as the foundation for a sustainable industry in the post-fumigation era. (Abstract shortened by UMI.)</p>

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Wholegrains have been linked with significant health benefits such as management of cardiovascular disease, diabetes and some cancers. This study aimed to add value to the grain industry by exploring new nutraceutical targets. This was achieved using bioassay guided fractionation. Wheat extracts including wholegrain, endosperm, pericarp and aleurone from different commercial varieties were investigated for in vitro bioactivity in antioxidant, glycosidic enzyme inhibition, anti-inflammatory, anti-cancer, immune function and cholesterol lowering assays. This study found wheat to have antioxidant activity as measured by oxygen radical absorbance capacity (ORAC) assays with higher values reported for the wheat bran extracts. Amino acid trytophan was identified as the most dominant antioxidant compound in the hard wheat variety durum with a TE value of 24217 ± 3158 µmol/g compound. The unsaturated fatty acids oleic, linoleic and linolenic acids proved to be responsible for the majority of the antioxidant activity in the hard wheat bran H2 with TE values of 2424 ± 274, 5220 ± 523 and 5542 ± 102 µmol/g compound, respectively. Wheat bran and germ but not wholegrain or endosperm displayed α-glucosidase and α-amylase inhibiting properties. Through bioassay guided fractionation, phosphoglycerides, 1,2-linoleoylglycero-3-phosphate and 1-palmitoyl-2-linoleoylglycero-3-phosphate were deemed responsible for the α-glucosidase inhibition. Crude wheat extracts were not cytotoxic to a number of human cancerous cell lines. However, some specific fractions showed selective cytotoxicity to the PC3 human prostate tumour cell line. These fractions contained a number of alkylresorcinols with comparative IC50 values (µg/mL) 5-(2-oxotricosanyl)resorcinol (10.9), trans 5-(14-nonadecenyl)resorcinol (13.7), 5-heptadecylresorcinol (22.5) and trans 5-(16-heneicosyl)resorcinol (42.2) to the known anti-cancer agent Chlorambucil (58.7). In this study, wheat bran extracts have not shown any anti-inflammatory inhibition, estrogen binding inhibition, cholesterol lowering or immune function activity. Wheat bran has proved to be a highly nutritious by-product of the wheat milling industry with a number of protective health effects

Thesis (Ph. D.)--University of Adelaide, 1990. / Typescript (Photocopy). Includes bibliographical references (leaves i-xii. (3rd paging sequence)).

Thesis (M.Ag.Sc.) -- University of Adelaide, Dept. of Plant Science, 1991. / Includes bibliographical references (p. 230-281).

Thesis (Ph.D.) -- University of Western Sydney, Hawkesbury, 1999. / Thesis submitted for the degree of Doctor of Philosophy. Spine title: Towards an understanding of vitrification in tissue cultured plants. Includes bibliographical references (leaves 175-203).

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references. Also available via the Internet.

Thesis (M.S.)--University of Missouri-Columbia, 2004. / Typescript. Includes bibliographical references (leaves 84-87). Also available on the Internet.