Submitted by Nathália Faria da Silva (nathaliafsilva.ufv@gmail.com) on 2017-07-19T13:10:28Z No. of bitstreams: 1 texto completo.PDF: 335975 bytes, checksum: 38b076faf12bdd91bf8a9c7659aa9560 (MD5) / Made available in DSpace on 2017-07-19T13:10:28Z (GMT). No. of bitstreams: 1 texto completo.PDF: 335975 bytes, checksum: 38b076faf12bdd91bf8a9c7659aa9560 (MD5) Previous issue date: 2001-03-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A seletividade do flumioxazin foi avaliada nos cultivares de soja UFV-16 e Doko RC, em solo com três níveis de água, em casa de vegetação, e em CAC-1, em condições de campo. Em casa de vegetação, o delineamento experimental foi o inteiramente casualizado, com os tratamentos distribuídos em esquema fatorial 2x3x4, sendo dois cultivares e três níveis de água no solo (75, 85 e 100 dag.kg -1 da capacidade de campo) associados: a) testemunha, b) flumioxazin (25 g.ha -1 ), c) adjuvante {Iharaguen-s + TS 303 0,5 e 0,1 L.ha -1 p.c (produto comercial), respectivamente} e d) flumioxazin (25 g.ha -1 ) + adjuvante (Iharaguen-s + TS 303 0,5 e 0,1 L.ha -1 p.c., respectivamente). No campo, o delineamento usado foi o de blocos casualizados com quatro repetições e tratamentos dispostos em parcelas subdivididas em faixas, onde os herbicidas foram os tratamentos principais, sendo os tratamentos secundários (capina e sem capina) distribuídos nas faixas ao longo do bloco. Os tratamentos com os herbicidas envolveram flumioxazin (15 e 25 g.ha -1 ) combinado com Iharaguen- s (500 mL.ha -1 p.c.), TS 303 (50, 100 e 150 mL.ha -1 p.c), chlorimuron-ethyl (12,5 g.ha -1 ) e fomesafen (200 g.ha -1 ). A toxicidade do flumioxazin à cultura da soja não foi influenciada pelos níveis de água do solo; a adição de adjuvante à calda aumentou em 45% a toxicidade do flumioxazin em relação ao produto puro, reduzindo a altura das plantas do cultivar Doko RC em média 27% em relação à testemunha, o que não ocorreu com o UFV-16. A elevação da umidade no solo proporcionou aumento na altura das plantas do cultivar UFV- 16. A produção de grãos foi reduzida em média 14% em relação à testemunha e apresentou o maior peso de 100 sementes (14,16 g) quando o flumioxazin foi aplicado juntamente com o adjuvante, não sendo estas influenciadas pelos níveis de água no solo. Em condições de campo, o flumioxazin nas doses de 15 e 25 g.ha -1 , misturado com Iharaguen-s, causou toxicidade em torno de 50% à soja CAC-1; o TS 303 adicionado à calda reduziu a toxicidade em 10% com a menor dose do flumioxazin. Esses resultados permitem concluir que o flumioxazin, quando aplicado isoladamente, é seletivo nos cultivares de soja avaliados, não sendo tal seletividade influenciada pelos níveis de água no solo. A adição do adjuvante à calda reduziu a produção de grãos em condições de casa de vegetação. No campo, o cultivar CAC-1 recuperou-se completamente da toxicidade inicial, atingindo produções semelhantes à da testemunha capinada. / The selectivity of flumioxazin was evaluated in the soybean cultivars UFV-16 and Doko RC, in greenhouse and three levels of soil water, and in CAC-1 in the field. The experimental design in the greenhouse was entirely randomized, with treatments distributed in factorial arrangement 2x3x4, with the association of two cultivars and three levels of soil water (75, 85 and 100 dag.kg -1 of the field capacity): a) control, b) flumioxazin (25g.ha -1 ), c) adjuvant {lhraguen-s + TS 303 0.5 and 0.1 l.ha -1 c.p. (commercial product), respectively} and d) flumioxazin 25 g.ha -1 ) + adjuvant (lhraguen-s + TS 303 0.5 and 0.1 l.ha -1 c.p., respectively). The experimental design in the field was randomized blocks with four repetitions and the treatments distributed in split-plots within strips, in which the herbicides were the main treatments, and the secondary treatments (with and without weeding) were distributed in the strips along the block. The treatments with herbicide consisted of flumioxazin (15 and 25 g.ha -1 ) combined with lharaguen-s (500 ml.ha -1 c.p.), TS 303 (50, 100 and 150 ml.ha -1 c.p.), chlorimuron-ethyl (12.5 g.ha -1 ) and fomesafen (200 g.ha -1 ). Fumioxazin toxicity to the soybean crop was not influenced by the levels of soil water; addition of adjuvant to the aqueous solution increased flumioxazin toxicity in 45% compared to pure product, decreasing plant height of cultivar Doko RC in average 27% compared to control, what did not happened to UFV-16. Plant height of cultivar UFV-16 increased with soil moisture increase. Grain yield was reduced 14% on average compared to the control, and gave the largest 100- seed weight (14.16 g) when Flumioxazin was applied together with the adjuvant, both not being influenced by the levels of water in the soil. In field conditions, 15 and 25 g.ha -1 doses of flumioxazin, mixed with lharaguen-s, caused approximately 50% of toxicity to soybean CAC-1; TS 303 added to the aqueous solution with 15 g.ha -1 of flumioxazin caused reduction of 10% in toxicity. The results obtained permit the following conclusions; flumioxazin applied separately is selective in the assayed soybean cultivars, and such selectivity is not influenced by the levels of soil water; addition of adjuvant to the aqueous solution reduced grain yield in the greenhouse conditions; cultivar CAC-1, in the field, had a complete recovery from the initial toxicity, reaching yields similar to the weeded control.

Thesis(M.S.)--Auburn University, 2006. / Abstract. Vita. Includes bibliographic references.

Doctor of Philosophy / Department of Agronomy / J. Anita Dille / Integrated weed management (IWM) is an ecological approach to weed control that reduces dependence on herbicides through understanding of weed biology and involves using multiple weed control measures including cultural, chemical, mechanical and biological methods. The critical period of weed control is the duration of the crop life cycle in which it must be kept weed-free to prevent yield loss from weed interference. Eight experiments were conducted throughout Kansas between October 2010 and June 2012 to identify this period in winter wheat grown under dryland and irrigated conditions. Impact of henbit and downy brome density on winter wheat yields were evaluated on four farmer’s fields with natural populations and on a research station with overseeded populations. Henbit density up to 156 plants m-2 did not affect winter wheat yield, while downy brome at a density of 40 plants m-2 reduced yield by 33 and 13% in 2011 and 2012, respectively. In the presence of downy brome, winter wheat should be kept weed-free approximately 30 to 45 days after planting to prevent yield loss; otherwise, weeds need to be removed immediately following release from winter dormancy to prevent yield loss due to existing weed populations. Flumioxazin and pyroxasulfone are herbicides registered for use in winter wheat, soybean and corn for control of broadleaf and grass weeds. Flumioxazin and pyroxasulfone were evaluated for plant response to localized herbicide exposure to roots, shoots, or both roots and shoots utilizing a novel technique. Two weed species, ivyleaf morningglory and shattercane, as well as two crops, wheat and soybean, were evaluated for injury after localized exposures. The location and expression of symptoms from the flumioxazin and pyroxasulfone herbicides were determined to be the shoot of seedling plants. The utilization of preemergence herbicides in winter wheat is not a common practice, although application may protect winter wheat from early season yield losses as determined by the critical weed-free period. Kansas wheat growers should evaluate the presence and density of weed species to determine which weed management strategy is most advantageous to preserving winter wheat yield.

The indeterminate nature of lentil (Lens culinaris Medik), in conjunction with adverse field conditions, can lead to varying degrees of maturity among plants at harvest. This variable maturity may have a negative influence on lentil production and can delay harvest. Desiccants are currently used to improve lentil crop dry-down. However, applying desiccants too early may result in reduced crop yield and quality, and also leave unacceptable herbicide residues in lentil seeds. In addition, only four herbicides (glyphosate, diquat, saflufenacil, and glufosinate) are registered as desiccants for lentil desiccation in Canada, which limits options for growers. Therefore, the objectives of this thesis were i) to determine the importance of desiccant application timing in affecting crop yield and quality, as well as herbicide residues and ii) to determine whether additional desiccants applied alone or tank-mixed with glyphosate provide better crop desiccation. Field trials were conducted at Saskatoon and Scott, Saskatchewan, from 2012 to 2014. In the application timing trial, glyphosate or saflufenacil alone, or glyphosate+saflufenacil generally decreased seed yield, thousand seed weight, and crop dry-down, and increased herbicide residue levels at earlier application timings. For example, when applied at 60% seed moisture, saflufenacil reduced yield and thousand seed weight by 22% and 10%, respectively, and resulted in glyphosate and saflufenacil residues greater than 2.0 and 0.03 ppm, respectively. Although there were no reductions in yield and thousand seed weight when desiccants were applied at 50% or 40% seed moisture, glyphosate residue exceeded 2.0 ppm. Application of desiccants at 20 or 30% seed moisture content had no effect on yield, thousand seed weight, or herbicide residues. These results indicate that desiccant application timing is critical, and should not be made before 30% seed moisture. In a second study, glufosinate and diquat tank mixed with glyphosate were the most consistent desiccants and provided optimal crop dry-down without reducing yield and thousand seed weight, and effectively reduced glyphosate residue. The other herbicides tested (pyraflufen-ethyl and flumioxazin) were found to be poor options for growers as they had sub-optimal crop desiccation and did not affect glyphosate residue.

No description available.

To understand the flow of water as a factor that influences aquatic vegetation communities and aquatic plant dispersal, custom-made Global Positioning System (GPS) drones were used to monitor the movement of water in Aliceville Lake, Columbus Lake, and Ross Barnett Reservoir, MS. In each reservoir, the drones drifted in the wind-generated surface current. Analysis of wind speeds suggests that a certain wind speed may be necessary to overcome gradient flow. Wind direction and wind speed should be incorporated in future spatial simulation models for aquatic plant dispersal and distribution. An herbicide evaluation on Cuban bulrush (Oxycaryum cubenese) was conducted to determine what herbicides would effectively control the invasive species. Applications made prelowering were more successful than postlowering applications for all herbicides tested with glyphosate, 2,4-D, triclopyr, diquat, imazamox, and imazapyr resulting in 100% mean biomass reduction. For postlowering applications, glyphosate, triclopyr, and diquat are recommended.