Research was conducted in 2012 and 2013 to evaluate the use of saflufenacil in rice (Oryza sativa L.). Studies included a preemergence evaluation of different rates of saflufenacil in comparison to one rate of carfentrazone, a postemergence evaluation of saflufenacil at different rates and carfentrazone at one rate at different postemergence timings, an adjuvant evaluation to assess rice injury and weed control from different adjuvants when mixed with saflufenacil, a Clearfield program evaluation where saflufenacil was compared to other broadleaf herbicides in a Clearfield weed control program, and a cultivar tolerance evaluation where postemergence applications of saflufenacil were compared to carfentrazone on five different commercial rice cultivars.

Sharppod morningglory is a perennial vine commonly found infesting croplands in Texas and the southeastern United States. Previous research regarding morningglory competition and control primarily focused on annual Ipomoea. Interference, control, and herbicide translocation of sharppod morningglory could differ from that of other morningglories because of differences in growth and resource allocation. Therefore, field and laboratory experiments were conducted from 2001 to 2004 to: 1) determine the effects of seed-propagated and root-sprouted sharppod morningglory on cotton economic value, yield, harvest efficiency, and fiber quality; 2) evaluate sharppod morningglory control with cotton herbicides, and determine the effect of diuron rates on glyphosate absorption and translocation; and 3) assess the impact of cotton herbicide program and cotton-corn rotation on weed species composition over three years. A relatively large proportion of sharppod morningglory biomass was accumulated belowground during the first 8 wk of growth in the greenhouse. Consequently, up to 6 plants 10-m row-1 did not significantly reduce cotton lint yield. Sharppod morningglory density impacted color grade more than any other classification parameter. Through combined effects on yield and quality, cotton lint value was reduced by approximately 85% in the presence of 8 sharppod morningglory 10 m-1. Glyphosate alone did not completely control sharppod morningglory. The use of glufosinate, bromoxynil, or a combination of glyphosate plus diuron provided acceptable control. Sharppod morningglory absorbed up to 75% of glyphosate when applied alone, but most glyphosate was retained in treated leaves and did not translocate well. Diuron decreased absorption, increased leaf retention, and inhibited glyphosate translocation to roots. Rotation to corn and the use of preemergence herbicides in cotton improved control of grass and broadleaf weeds during the year of treatment. In the season following the 3-yr rotation, there were no lasting effects of crop rotation on density or control of grasses and broadleaves. However, hand-hoed and herbicide treated plots resulted in weed densities 2- to 3-fold lower than the untreated. Preemergence herbicides and/or crop rotation can reduce weed density and improve weed control, but these strategies must be employed long-term to reduce density of problematic weeds through depletion of the soil seedbank.

The resistance of Palmer amaranth (PA) and the tolerance (natural resistance) of pitted morningglory (PM) to glyphosate have made these species among the most common and troublesome weeds in the southeastern U.S. since the adoption of glyphosate-resistant (GR) crops. Populations of GR PA (R1 and R2) were identified in Mississippi. The inheritance of glyphosate resistance was examined in reciprocal crosses (RC) between glyphosate-resistant (R) and -susceptible (S) parents (Female-S × Male-R, S/R, and Female-R × Male-S, R/S), and second reciprocal crosses (2RC) (Female-S/R × Male-S/R, S/R//S/R, and Female-R/S × Male-R/S, R/S//R/S). Dose-response assays resulted in 17- to 4old resistance to glyphosate compared with S. Population S accumulated 325- and 8-times more shikimate at the highest glyphosate dose than in R1 and R2, respectively. cDNA sequence analysis of the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene indicated no target site mutation. Genomes of R1, R2, RC, and 2RC contained from 1- to 59old more copies of EPSPS gene than S; EPSPS was highly expressed in R1 and R/S, but was poorly expressed in S, S/R, and R2. EPSPS activity was lower in S and S/R than in R and R/S, glyphosate absent; all were inhibited by glyphosate. Western Blot analysis confirmed an increased EPSPS protein level to EPSPS copy number correlation. Thus, the level of resistance was decidedly influenced by the direction of the cross. R and S female plants were reproductively isolated and seed were still produced, suggesting that PA can produce seed both apomictically and sexually (facultative apomixis). This mode of reproduction determined the low copy number inheritance, as well as guaranteeing the GR trait stability in the R populations. Dose-response assays resulted in 2.6old variability in tolerance to glyphosate between the most tolerant (MT) and the least tolerant (LT) PM populations. The level of tolerance positively correlated with the time of exposure to GR-crop system. Less shikimate was recovered in MT as compared to LT. Levels of aminomethylphosphonic acid (AMPA) were not different between populations and sarcosine was not present in either populations. Consequently, metabolism of glyphosate to AMPA or sarcosine is not a common factor in explaining natural resistance levels.

A utilização de compostos químicos no controle de pragas que afetam negativamente a produção agrícola tem sido objeto de muitas críticas por parte de ambientalistas e pesquisadores devido aos problemas ambientais proporcionados por tais substâncias. Nos últimos anos tem-se dedicado bastante tempo e recursos em pesquisas que levem à descoberta de produtos para controle de pragas que tragam nenhum ou o menor prejuízo possível ao ambiente. Neste sentido, o estudo da alelopatia busca a utilização de compostos oriundos da própria natureza para uso no combate a espécies invasoras em plantações, na esperança de ter-se um controle prático e efetivo sobre plantas daninhas minimizando-se a contaminação ambiental. Neste trabalho foram utilizaram-se extratos aquosos de sementes e folhas da leguminosa feijão-de-porco (Canavalia ensiformis) como um bioerbicida pós-emergente aplicado no controle das plantas daninhas trapoeraba (Commelina benghalensis) e corda-de-viola (Ipomoea grandifolia), e foi avaliada também a seletividade dos extratos com relação a cultivares de soja (Glycine max) convencional e transgênica. Foram preparados tratamentos em seis diferentes concentrações e aplicados em três diferentes períodos, sendo avaliados seus efeitos de toxicidade e seletividade sobre o desenvolvimento das plantas daninhas e da soja. Os resultados foram submetidos à análise de variância e aplicou-se o teste F a 1% de probabilidade, mostrando que os tratamentos mais eficazes no controle das invasoras foram aqueles preparados a partir das sementes de feijão-de-porco nas concentrações 25 e 50 g L-1, que interromperam completamente o desenvolvimento as plantas daninhas, sem causar, no entanto qualquer efeito aparente sobre a soja, tanto transgênica quanto convencional. Foram realizadas também determinações cromatográficas para identificação de compostos fenólicos em amostras de folhas de feijão-de-porco. Mediante a comparação com compostos padrão e variação de comprimento de onda na região do ultravioleta-visível foi possível identificar os compostos ácido clorogênico, ácido p-anísico, naringina e rutina, cujas concentrações encontradas, relativas às amostras, foram de 4,42 mg L-1, 6,0 mg L-1, 3,75 mg L-1 e 5,0 mg L-1 respectivamente. / The use of chemicals to control pests that adversely affect agricultural production has been treated with great concern due environmental issues provided by such substances. In the last years much time and money were devoted in researchs leading to discovery products to control pests that bring no or the least damage to the environmet. In this sense, the use of allelopathic species for controlling invasive species is an environmental friendly technique. In this work aqueous extracts of seeds and leaves of Jack bean (Canavalia ensiformis) were used as a post-emergent bioherbicide succesfully applied for control of dayflower (Commelina benghalensis) and morningglory (Ipomoea grandifolia), and selectivity on conventional and transgenic soybean (Glycine max) cultivars. Treatments were prepared in six different concentrations and applied in three different periods, being analyzed the effects of toxicity and selectivity on the development of weeds and soybean. The results were subjected to analysis of variance and applied the F test at 1% probability, showing that the most effective treatments in controlling the weeds were those prepared from seeds of Jack bean at concentrations of 25 and 50 g L-1, that totally controlled weeds, however causing no apparent injury on soybeans, both transgenic and conventional. Chromatographic analysis were also performed for identification of phenolic compounds in samples of Jack bean leaves. By comparison with standards and changes in wavelength on ultraviolet-visible spectra was possible to identify clorogenic acid, p-anisic acid, naringin and rutin compounds at concentrations of 4.42 mg L-1, 6.0 mg L-1, 3.75 mg L-1 and 5.0 mg L-1 respectively.

A utilização de compostos químicos no controle de pragas que afetam negativamente a produção agrícola tem sido objeto de muitas críticas por parte de ambientalistas e pesquisadores devido aos problemas ambientais proporcionados por tais substâncias. Nos últimos anos tem-se dedicado bastante tempo e recursos em pesquisas que levem à descoberta de produtos para controle de pragas que tragam nenhum ou o menor prejuízo possível ao ambiente. Neste sentido, o estudo da alelopatia busca a utilização de compostos oriundos da própria natureza para uso no combate a espécies invasoras em plantações, na esperança de ter-se um controle prático e efetivo sobre plantas daninhas minimizando-se a contaminação ambiental. Neste trabalho foram utilizaram-se extratos aquosos de sementes e folhas da leguminosa feijão-de-porco (Canavalia ensiformis) como um bioerbicida pós-emergente aplicado no controle das plantas daninhas trapoeraba (Commelina benghalensis) e corda-de-viola (Ipomoea grandifolia), e foi avaliada também a seletividade dos extratos com relação a cultivares de soja (Glycine max) convencional e transgênica. Foram preparados tratamentos em seis diferentes concentrações e aplicados em três diferentes períodos, sendo avaliados seus efeitos de toxicidade e seletividade sobre o desenvolvimento das plantas daninhas e da soja. Os resultados foram submetidos à análise de variância e aplicou-se o teste F a 1% de probabilidade, mostrando que os tratamentos mais eficazes no controle das invasoras foram aqueles preparados a partir das sementes de feijão-de-porco nas concentrações 25 e 50 g L-1, que interromperam completamente o desenvolvimento as plantas daninhas, sem causar, no entanto qualquer efeito aparente sobre a soja, tanto transgênica quanto convencional. Foram realizadas também determinações cromatográficas para identificação de compostos fenólicos em amostras de folhas de feijão-de-porco. Mediante a comparação com compostos padrão e variação de comprimento de onda na região do ultravioleta-visível foi possível identificar os compostos ácido clorogênico, ácido p-anísico, naringina e rutina, cujas concentrações encontradas, relativas às amostras, foram de 4,42 mg L-1, 6,0 mg L-1, 3,75 mg L-1 e 5,0 mg L-1 respectivamente. / The use of chemicals to control pests that adversely affect agricultural production has been treated with great concern due environmental issues provided by such substances. In the last years much time and money were devoted in researchs leading to discovery products to control pests that bring no or the least damage to the environmet. In this sense, the use of allelopathic species for controlling invasive species is an environmental friendly technique. In this work aqueous extracts of seeds and leaves of Jack bean (Canavalia ensiformis) were used as a post-emergent bioherbicide succesfully applied for control of dayflower (Commelina benghalensis) and morningglory (Ipomoea grandifolia), and selectivity on conventional and transgenic soybean (Glycine max) cultivars. Treatments were prepared in six different concentrations and applied in three different periods, being analyzed the effects of toxicity and selectivity on the development of weeds and soybean. The results were subjected to analysis of variance and applied the F test at 1% probability, showing that the most effective treatments in controlling the weeds were those prepared from seeds of Jack bean at concentrations of 25 and 50 g L-1, that totally controlled weeds, however causing no apparent injury on soybeans, both transgenic and conventional. Chromatographic analysis were also performed for identification of phenolic compounds in samples of Jack bean leaves. By comparison with standards and changes in wavelength on ultraviolet-visible spectra was possible to identify clorogenic acid, p-anisic acid, naringin and rutin compounds at concentrations of 4.42 mg L-1, 6.0 mg L-1, 3.75 mg L-1 and 5.0 mg L-1 respectively.

Field studies were conducted during 2006 and 2007 to evaluate control of saw greenbriar and southern dewberry by various pasture herbicides and to assess forage tolerance of Tifton 85 bermudagrass to these herbicides. Herbicides evaluated in each study included triclopyr, picloram, 2,4-D, fluroxypyr, dicamba, aminopyralid, metsulfuron methyl and various combinations of the above. Visual ratings were taken on each herbicide efficacy experiment. Visual evaluations of phytotoxicity, measurements of dry matter yield, and forage quality were quantified for each of the bermudagrass tolerance trials. Saw greenbriar was best controlled at approximately one year after treatment by triclopyr at 10.9% ae v/v with diesel as the carrier (88-98%), although the lower rate of triclopyr + diesel at 0.87% ae v/v + 5% v/v and triclopyr alone at 0.87% ae v/v provided 49 to 86% control. Triclopyr + fluroxypyr at 0.25% ai v/v + 0.086% ai v/v gave best control of southern dewberry in both years when applied as an individual plant treatment (IPT) six weeks after shredding. In general, shredding 45 days prior to herbicide application gave an advantage to southern dewberry control versus not shredding. In 2006, triclopyr + fluroxypyr (IPT) was the only treatment to decrease Tifton 85 dry matter yield at the first harvest, with no effect observed at the second harvest. In 2007, both broadcast treatments containing triclopyr + fluroxypyr and the IPT treatment of triclopyr decreased dry matter yield at the first harvest, with triclopyr (IPT) being the only treatment to lower dry matter yield at the second harvest. Field studies were also conducted in 2006 and 2007 to assess sharppod morningglory control in Roundup Ready Flex® and LibertyLink® cotton systems. Herbicides evaluated included glyphosate, glufosinate, prometryn, fluometuron, and diuron. Visual ratings of percent weed control and sharppod morningglory plant counts were taken to assess control. Prometryn at 1.8 kg ai ha⁻¹ and fluometuron at 1.8 kg ai ha⁻¹ provided significant preemergence control (33-81%) of seedling sharppod morningglory. All rates of glyphosate (1.06 and 1.54 kg ai ha⁻¹) and glufosinate (0.45 and 0.6 kg ai ha⁻¹) controlled sharppod morningglory from 55 to 100% at both application timings. The addition of diuron at 1.12 kg ai ha⁻¹ to glyphosate and glufosinate at the late season application enhanced sharppod morningglory control by 3 to 16%. Additionally, in both years, no reduction in cotton yield was observed in the morningglory infested treatment when compared to the weed free treatment.