Thesis (M. Phil.)--University of Queensland. / Includes bibliographical references.

Commercial development of the fungicide prochloraz for the control of pre- and post-harvest diseases in fruit crops has been restricted by the occasional occurrence of 'musty' taints. The primary aims of this research were to identify the cause of taint and and its means of formation. Sensitive and selective residue methodology based upon determination by gas chromatography with mass selective detection was devised, validated and used to establish 2,4,6-trichloroanisole (2,4,6-TCA) as the direct cause of taint by analysis of field-treated samples and studies involving 14C-radiolabelled prochloraz. Evaluation of analytical results in conjunction with corresponding sensory data led to proposals of flavour threshold levels ranging between 0.04 and 1.0mug/kg for 2,4,6-TCA in different fruit types. Formation of the anisole in pre-harvest treatment situations was shown to proceed via the minor plant metabolite 2,4,6-trichlorophenol (2,4,6-TCP) as the direct precursor; under post-harvest conditions, however, metabolism of prochloraz was minimal, and 2,4,6-TCA taints arose primarily from 2,4,6-TCP as an impurity (measured at 0.9% w/w) in the commercial emulsifiable concentrate formulation. Detailed investigation of the relationship between 2,4,6-TCP and 2,4,6-TCA under controlled conditions demonstrated that certain fruit types possess a capacity for direct O-methylation of the phenol to the anisole, whereas others do not. These findings were generally consistent with occurrences of taints associated with prochloraz. Kinetic studies of the active O-methyltransferase system in apple homogenates indicated the same Vmax value for 2-chlorophenol, 2,4-dichlorophenol, 2,6-dichlorophenol and 2,4,6-TCP. Reactivity in this series was found to be closely related to the ability of the molecules to to form effective nucleophiles for reaction with s-adenosylmethionine as the assumed methyl donor, and a linear relationship was established between chlorophenol pKa and log(apparent Km). The O-methylation of 2,4,6-TCP, whilst inhibited competitively by other o-chlorophenolic substrates, remained unaffected by the addition of representative plant o-diphenolics previously reported as substrates for O-methylation in plants.

No description available.

Thesis (M.S.)--University of Wisconsin--Madison, 1970. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

While there is growing public concern over the safety of the food supply, few studies have contrasted varying perceptions of pesticide risk. This study assessed and contrasted perceptions of three groups of Oregon State University Extension Service clientele (home food preservers, Master Gardener volunteers, commercial growers) and factors influencing these perceptions. The impact of the pesticide risk perceptions on purchasing decisions and pesticide application practices was assessed. Two questionnaires were developed: one for home food preservers/Master Gardener volunteers and one for commercial growers. One hundred twenty-seven questionnaires were completed by a convenience sample of home food preservers (85% adjusted return rate) and 155 questionnaires were completed by randomly selected Oregon State University Master Gardener volunteers (81% adjusted return rate). A shortened version of the questionnaire was completed by 124 participants at the annual meeting of Willamette Valley Processed Vegetable Growers. Home preservers were 84% female (mean age=49 ± 14 years), volunteers were 50% female/50% male (mean age=56 ±14 years), and commercial growers were 95% male (mean age=42 ± 11 years). Three different measures of pesticide risk perceptions were used to test six hypotheses: Respondents rated 1) "eating foods produced using pesticides" as high, low, or no risk, and agreed/disagreed (on Likert scales) whether 2) "chemical residues remaining on produce are a major health concern," and 3) "children are at a greater risk for illness from pesticides than adults." Produce selection decisions, pesticide application practices, life stages, gender, media awareness, and knowledge of agricultural production techniques and practices were also assessed to determine their relationship with risk perceptions. Perceptions of risk varied among the three groups. Fifty-five percent of preservers rated "eating foods produced using pesticides" as a "high" risk compared to 34% of volunteers and 2% of growers. Thirty-four percent of preservers strongly agreed that "chemical residues remaining on produce are a major health concern" compared to 25% of volunteers and 7% of growers. Forty-six percent of preservers strongly agreed that "children are at a greater risk of illness from pesticides than adults" compared to 42% of volunteers. Fifty-two percent of growers strongly/ somewhat agreed that children are at no greater risk. Gender was significantly associated with respondents' perceptions. Eighty-nine percent of preservers rating the risk of "eating food produced using pesticides" as "high" were female as were 65% of volunteers. Female volunteers moderately agreed that "chemical residues remaining on produce are a major health concern" compared to males who tended to neither agree nor disagree. The presence of children living in the home was significantly related to the volunteers' perceptions that chemicals are a major health concern and that children are at greater risk. Preservers and growers' results indicated there were no significant differences. Awareness of pesticide reports in the media was measured by recall of four media events. Media awareness was significantly associated with preservers' perceptions that eating foods produced with pesticides was "high" risk and that children are at a greater risk for illness because of pesticide residues. There was no media association for either volunteers or growers. Influence of risk perceptions on produce purchase decisions was measured with a series of questions about past, present, and future purchases. Results indicated that volunteers' pesticide risk perceptions were significantly related to more produce selection decisions than were home food preservers. The risk perception measure that "chemical residues remaining on produce are a major health concern" was most significantly associated with purchase decisions for both preservers and volunteers. For preservers and volunteers there were significant relationships between all three measures of pesticide risk perceptions and three of the twelve purchase decisions tested. Those who perceived a higher risk were 1) more willing to pay a higher price for certified residue free produce, 2) more concerned about pesticide residues when buying imported produce, and 3) intended to purchase produce grown without synthetic pesticides even if it costs more. Knowledge of agricultural practices was measured by a set of five questions. Mean scores ranged from 0.9 ± 0.9 for preservers to 1.6 ± 1.0 for volunteers out of a possible 5.0. Volunteers' with higher scores were significantly more likely to agree that chemicals are a major health concern and that children are at a greater risk of illness from pesticide residues. No significant associations were seen for preservers. Pesticide application practices were significantly related to pesticide risk perceptions. Preservers and volunteers who generally perceived the risks as "high" reported not using pesticides. Preservers reporting changes in application practices moderately agreed chemical residues are a major health concern while volunteers' reporting changes in application practices strongly agreed that children are at higher risk than adults. Growers tended to disagree that pesticides are a major health concern and they were less concerned that children are at a greater risk from pesticides. The study concluded that the home food preservers and Master Gardener volunteers perceived the risks associated with pesticides and produce as much higher than commercial vegetable growers. This difference in perceptions is reflected in some of their produce selection decisions and pesticide application practices. Children living at home, gender, media awareness, and knowledge of agricultural practices were associated with the pesticide risk perceptions of these Extension clientele. Results suggest that educational programming to increase knowledge about pesticide usage in agricultural production is warranted. There is also a need to foster better communications among groups with differing points of views about pesticide residue risks. / Graduation date: 1994

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. / Revised.

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.

No description available.

Thesis (DR. P.H.)--University of Michigan.

Thesis (Ph. D.)--University of California, Riverside, 2009. / Includes abstract. Includes bibliographical references. Issued in print and online. Available via ProQuest Digital Dissertations.