Thesis (Ph. D.)--University of Tennessee, Knoxville, 2009. / Title from title page screen (viewed on Nov. 2, 2009). Thesis advisor: Thomas C. Mueller. Vita. Includes bibliographical references.

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

Thesis (M.S.)--Oregon State University, 2001. / Typescript (photocopy). Includes bibliographical references. Also available online.

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

Thesis (M.Agr.St.) - University of Queensland, 2005. / Includes bibliography.

Management of volunteer horseradish is a major challenge in fields when horseradish is included in the crop rotation. Three field studies were conducted: 1) to evaluate the growth habit and density of volunteer horseradish, 2) to evaluate the efficacy of fall herbicide applications for control of volunteer horseradish, 3) to evaluate the tolerance of subsequent horseradish crops to persisting soil residues of halosulfuron. One year following horseradish production, field infestations of volunteer horseradish ranged from 0.08 to 6.60 plants/m2 with the majority of plants emerging from established roots left below the depth of horseradish harvest and tillage. Fall herbicide applications provided effective control of volunteer horseradish compared to the nontreated control. Combinations of 2,4–D tank–mixed with glyphosate, iodosulfuron, halosulfuron, or rimsulfuron:thifensulfuron achieved the greatest control of volunteer horseradish and reduced volunteer horseradish densities to less than 1 plant /m2, while glyphosate alone provided the least control and density reduction. In addition to volunteer horseradish control, combinations of 2,4–D with glyphosate, iodosulfuron, halosulfuron, or rimsulfuron:thifensulfuron also provided 97% or greater control of winter annual weeds (henbit, common chickweed, and Carolina foxtail). Although the herbicide halosulfuron is very effective at controlling volunteer horseradish, it has the potential to injure future horseradish crops due to soil persistence. Field studies showed that after 4 months following a June halosulfuron application, horseradish can be replanted with no visual injury or reduction in root biomass. Tillage may provide temporary removal of volunteer horseradish plants, however, herbicide applications (e.g., 2,4–D with halosulfuron, iodosulfuron or rimsulfuron:thifensulfuron) provide the most consistent, complete control of volunteer horseradish.

Reproductive endpoints are generally not considered in regulatory risk assessments used to inform registration decisions for pesticides, and relatively few studies have examined effects of herbicides on reproduction in non-target plants. In two sets of greenhouse experiments using three wild species (Rudbeckia hirta L., Centaurea cyanus L. and Trifolium pratense L), effects on flowering phenology and inflorescence characteristics were investigated following low, drift-equivalent glyphosate exposure at an early bud stage. Weekly post-spray observations included the number of inflorescences, aborted buds and malformed inflorescences. In the experiment focusing on inflorescence characteristics (C. cyanus and T. pratense only), inflorescences and pollen were collected at five weeks post-spray to measure inflorescence dry weight, count the number of reproductive florets, estimate the amount of pollen per floret, and assess pollen germination in vitro. Flower production was adversely affected in all three species, including delays in flowering, significant increases in the number of aborted buds and malformed inflorescences, an overall reduction in the number of inflorescences produced, as well as a reduction in the duration of individual inflorescence bloom time (R. hirta and T. pratense assessed only). Inflorescence dry weight and in vitro pollen germination were significantly reduced for C. cyanus exposed to glyphosate, but not for T. pratense. However, both species experienced a significant reduction in the number of reproductive florets produced per inflorescence in response to glyphosate exposure. Neither species was observed to have significant reductions in the amount of pollen produced per reproductive floret. These results have important implications for risk assessment, demonstrating that current glyphosate use in Canada and elsewhere could be adversely affecting non-target flowering plants in field margins, as well as other taxa that rely on them, particularly pollinators. Les effets sur la reproduction des plantes ne sont généralement pas pris en ligne de compte dans les évaluations réglementaires sur les risques des pesticides lors de leur homologation. De plus, relativement peu d'études ont examiné les effets des herbicides sur la reproduction des plantes non ciblées. Dans deux séries d'expériences en serres avec trois espèces sauvages (Rudbeckia hirta L., Centaurea cyanus L. et Trifolium pratense L), les effets sur la phénologie florale et les caractéristiques des inflorescences ont été étudiés après une faible exposition au glyphosate équivalente à la dérive durant la pulvérisation lorsque les plantes sont au début des boutons floraux. Des observations hebdomadaires post-pulvérisation ont été effectuées sur le nombre d'inflorescences, de bourgeons avortés et d’inflorescences malformées. Dans l'expérience portant sur les caractéristiques des inflorescences (C. cyanus et T. pratense seulement), les inflorescences et le pollen ont été recueillis cinq semaines après la pulvérisation pour mesurer le poids sec des inflorescences, compter le nombre de fleurons reproducteurs, estimer la quantité de pollen par fleur et évaluer la germination du pollen in vitro. La production de fleurs a été affectée chez les trois espèces, y compris des retards de floraison, des augmentations significatives du nombre de bourgeons avortés et d’inflorescences malformées, une réduction globale du nombre d'inflorescences produites et une diminution de la durée de floraison par inflorescence. (R. hirta et T. pratense évalués seulement). Le poids sec des inflorescences et la germination in vitro du pollen ont été significativement réduits chez C. cyanus exposé au glyphosate, mais pas chez T. pratense. Cependant, les deux espèces ont subi une réduction significative du nombre de fleurons reproducteurs produits par inflorescence en réponse à l'exposition au glyphosate. Aucune des deux espèces n'a montré de réduction significative de la quantité de pollen produit par fleuron. Ces résultats ont des implications importantes pour l'évaluation de risques, démontrant que le glyphosate, tel qu’utilisé présentement au Canada et ailleurs, pourrait nuire aux plantes à fleurs non ciblées retrouvées en bordure de champs, ainsi qu'à d'autres taxons qui en dépendent, particulièrement les pollinisateurs.

This study was conducted to provide insight into the response of Achyranthes japonica to management tools in the form of complete shoot removal (clipping) and herbicide application at Cypress Creek National Wildlife Refuge (CCNWR) in southern Illinois. Field herbicide experiments indicate that A. japonica is susceptible to foliar applications of systemic, broad leaf herbicides. The removal of A. japonica by herbicide, however, did not allow for re-establishment of the surrounding plant community in years 2011 and 2012. Seedlings at node stage 3, 4 and 6 were able to regrow following complete shoot removal indicating that this species can sustain perennial growth when it develops three nodes and that the node stage at which plants were clipped did not affect their regrowth potential. In the greenhouse, A. japonica was able to regrow following complete shoot removal at the 3 node stage and the number of branches and apical nodes on a plant are the best predictors of the regrowth potential for this species. Achyranthes japonica's susceptibility to foliar applications of systemic herbicides in the greenhouse was high. Herbicide titration results indicate that of the six herbicides tested (2,4-D ester, triclopyr, glyphosate, aminopyralid, triclopyr+fluroxypyr, and aminopyralid+metsulfuron) triclopyr required the least amount of active ingredient to reduce the growth of A. japonica by 50% (GR-50). Results overall suggest that A. japonica reaches perennial growth by the time it has three nodes, making clipping as a management tool only successful if done before plants have developed three nodes. Achyranthes japonica perennial plants are highly susceptible to foliar applications of broad leaf systemic herbicides making them a good management tool in the field.

Made available in DSpace on 2014-06-11T19:35:07Z (GMT). No. of bitstreams: 0 Previous issue date: 1999Bitstream added on 2014-06-13T19:05:18Z : No. of bitstreams: 1 santos_tcr_dr_araiq.pdf: 3624220 bytes, checksum: f06a06f02effa5bf8d56e04e45a3b1f8 (MD5) / A aplicação de um pesticida sobre culturas agrícolas implica em processos de transformação do composto e no consequente aparecimento de produtos de degradação resultantes desses processos. Em campos de arroz onde, em geral, o cultivo é feito em solos alagados, as condições peculiares levam a processos característicos, predominando mecanismos diferentes daqueles observados nas culturas feitas em solos secos. Embora o herbicida propanil seja extensivamente utilizado em cultivos de arroz, poucos estudos têm tratado da degradação nas condições comumente encontradas nos campos. Propanil e seu produto de degradação majoritário, 3,4-dicloroanilina (DCA), foram monitorados em águas e solo de campos de arroz do Delta do Ebro (Espanha). A determinação em amostras de água foi feita por análise on-line SPE/LC/DAD/APCI-MS, utilizando como adsorvente estireno-divinilbenzeno (PLRP-S). Para amostras de solo, a extração foi feita com metanol (em sistema Soxhlet) e clean-up com Florisil. A análise por cromatografia líquida permitiu detecção sensível e reprodutiva por conjunto de diodos, bem como a confirmação inequívoca dos compostos por espectrometria de massas. As concentrações do herbicida nas águas dos campos de arroz variaram entre 1,89-71,07 ng/mL, enquanto maiores concentrações foram determinadas para DCA (18,54-469,97 ng/mL). Os tempos de meia-vida calculados para o herbicida e seu principal produto de degradação foram de 1,24-3,83 e 1,58-1,63 dias, respectivamente. Em solo, a transformação do propanil também foi rápida, com persistência do DCA até um mês após a aplicação do herbicida (concentração de 119,7 ± 22,1 ng/g).O estudo de degradação do propanil nas condições controladas em laboratório evidenciou a influência da matéria orgânica no processo de transformação do herbicida. / The aplication of pesticide over cultivated areas implies changes to the compound, resulting in degradation products. In general, rice is cultivated in swampy areas; therefore, these peculiar conditions result in specific processes differing from those observed on dry soils. Although the extensive usage of propanil herbicide around the world, few studies concerning degradation on paddy field conditions have been carried out. Propanil and its major degradation product, 3,4-dichloroaniline (DCA), were monitored in surface water and soil samples from the rice fields of the Ebro Delta area (Spain). The determination in water samples was made by on-line SPE/LC/DAD/APCI-MS, using styrene-divinylbenzene copolymer (PLRP-S) as a sorbent material. In soil samples, the extraction was made with methanol (using Soxhlet system) and then clean-up with Florisil. The liquid chromatographic analysis allowed a sensitive and reproductive detection by diode array, and also an unequivocal confirmation by using a mass spectrometric detector. Propanil’s concentration in water samples of the rice fields varied from 1.89- 71.07 ng/mL, while higher concentrations of DCA were determined (18.54-469.97 ng/mL). The herbicide and its degradation product exhibited half-lives of 1.24-3.83 and 1.58-1.63 days, respectively. In the paddy soil, propanil also transformed very quickly to DCA, with the evidence of this compound being persistant up to one month after herbicidal application (concentration of 119.7 ± 22.1 ng/g). Under controled conditions the laboratory studies demonstrated the influence of organic matter over the herbicide transformation. A strong interaction with humic acids extracted from sediments pointed out that, besides the biological factors already stated in literature, other mechanisms also influence the propanil degradation.

Orientador: Joaquim Gonçalves Machado Neto / Banca: Marcelo da Costa Ferreira / Banca: Casimiro Dias Gadanha Júnior / Resumo: Os objetivos deste trabalho foram de quantificar as exposições dérmicas e respiratórias do tratorista em aplicações de herbicidas em cultura de cana-de-açúcar, avaliando a eficiência de pontas com indução de ar, da barra central e da cabina do trator, separadamente ou combinadas, como medidas de proteção coletiva e classificar as pulverizações das 46 recomendações de herbicidas para cultura de cana-de-açúcar em seguras ou inseguras, calculando o tempo de trabalho seguro e a necessidade e controle da exposição para as condições inseguras. O delineamento experimental utilizado foi o inteiramente ao acaso com os tratamentos distribuídos no esquema fatorial 2 x 2 x 2. O fator A foi a posição da barra no pulverizador (traseira ou central); o fator B a condição do trator (sem e com cabina); e o fator C o modelo da ponta de pulverização (TF Turbo Floodjet® - ou TTI Turbo TeeJet Air Induction®). A exposição dérmica potencial do tratorista foi reduzida em 46% com o uso da barra central, em 20% com a cabina e em 0,07% com as pontas TTI. Das 46 recomendações, 32,6% delas foram seguras com o pulverizador de barra central sem a cabina e com as pontas TF e 34,8% com as pontas TTI. Com a cabina, 36,9% foram seguras com as pontas TF e 39,1% com as pontas TTI. Com o pulverizador de barra traseira sem a cabina, 30,4% das recomendações foram seguras com as pontas TF e 28,3% com as pontas TTI. Com a cabina, 30,4% das recomendações foram seguras com as pontas TTI. A condição mais segura para o tratorista ocorreu com o pulverizador de barra central, trator com cabina e pontas TTI. A cabina do trator é eficiente como medida de proteção coletiva para o controle da exposição dérmica do tratorista em aplicações de herbicidas em cana-de-açúcar com pulverizadores de barra. / Abstract: The objectives of this work were to quantify the exposures dermal and respiratory of the tractor driver in herbicides applications in sugar-cane crop; to evaluate the efficiency of nozzles with air induction, of the central bar and of the cabin of the tractor, isolated or combined, as measures of collective safety for the tractor driver; and to classify the 46 recommendations the herbicides registered spraying for sugar-cane in safe or unsafe for the tractor driver in these work conditions. The used statistical arrangement was the completely randomized plot in the factorial outline 2 x 2 x 2. The factor A was the position of the bar in the sprayer; the factor B was the condition of the tractor; and the factor C was the model of the spraying tip (TF Turbo Floodjet® or TTI - Turbo TeeJet Air Induction®). The potential dermal exposure of the tractor driver was reduced in 46% with the use of the central bar, in 20% with the cabin and in 0,07% with the nozzles TTI, in spraying with extremely course drops. Of the 46 recommendations herbicides for sugar-cane crop, 32,6% of them were safe with the sprayer of central bar without the cabin and with the nozzle TF and 34,8% with the nozzle TTI. With the cabin, 36,9% were safe with the nozzle TF and 39,1% with the nozzle TTI. In the applications with the sprayer of back bar without the cabin, 30,4% of the recommendations were safe with the nozzle TF and 28,3% with the nozzle TTI. With the cabin, 30,4% of the recommendations were safe with the nozzle TTI. The safest condition for the tractor driver was the herbicides application with the sprayer with central bar, tractor with cabin and nozzle TTI. The cabin of the tractor is efficient as measure of collective protection for the control of the exposure dermal of the tractor driver in herbicides applications in sugar-cane with bar sprayer. / Mestre