Field and greenhouse experiments were conducted in 2008, 2009, and 2010 to evaluate the efficacy of glyphosate combined with other broadleaf herbicides on herbicide-resistant and -susceptible weeds in Illinois. In the field, the addition of lactofen or fomesafen to glyphosate provided the greatest consistency and control of problematic target weeds including common waterhemp and giant ragweed. Applications of glyphosate tank-mixtures at EPOST provided 10% greater control of giant ragweed compared with the same treatments at POST. The addition of a tank-mix herbicide with glyphosate provided the greatest impact on weed control when applied to glyphosate-resistant common waterhemp with control increasing by 67% compared with glyphosate applied alone. The addition of a tank-mix herbicide with glyphosate had little impact on control of PPO-resistant and herbicide-susceptible common waterhemp. Generally, the addition of an adjuvant to herbicide mixtures with glyphosate did not influence weed control 14 DAT compared with no additional adjuvant. However, the addition of PO-HSOC and SO-HSOC to glyphosate tank-mixtures containing fomesafen and cloransulam increased annual morningglory control compared with no additional adjuvant. In the greenhouse, PPO-inhibiting herbicides (fomesafen, lactofen, flumiclorac, fluthiacet) applied with glyphosate resulted in additive and antagonistic responses depending on the PPO-inhibitor used and the common waterhemp biotype. Generally, glyphosate tank-mixtures applied to PPO-resistant and herbicide-susceptible common waterhemp biotypes resulted in a greater frequency of antagonism than that of a glyphosate-resistant biotype. The efficacy of glyphosate tank-mixtures was also influenced by environmental conditions shortly before and after the herbicide application. Glyphosate tank-mixtures usually resulted in greater efficacy on common waterhemp when applied at 24 C with 75% RH than at 32 C with 40% RH, regardless of tank-mix herbicide or common waterhemp biotype. Although this research supports an improvement in control of glyphosate-resistant common waterhemp with the addition of PPO-inhibiting herbicides to glyphosate, the overall herbicide efficacy was still somewhat variable with evidence for environmental conditions that may alter efficacy of the tank mixtures. Thus, the use of preemergence, soil residual herbicides are still justified to reduce reliance on these postemergence herbicide mixtures for weed control in soybean and ultimately deter further selection of common waterhemp populations resistant to glyphosate and PPO-inhibiting herbicides.

O aumento no consumo mundial de soja demanda o uso de novas tecnologias em seu sistema de produção. Uma dessas tecnologias é a mudança de arquitetura da planta por meio da aplicação de reguladores de crescimento. Entretanto, esses produtos podem gerar danos à planta. Neste contexto, objetivou- se identificar os danos no metabolismo oxidativo em plantas de soja tratadas com reguladores de crescimento (hormônio e herbicidas em subdose) e verificar a presença de padrão de resposta entre variedades cultivadas do grupo de maturação (GM) 7.X (foram utilizadas as variedades cultivadas TEC 7849 IPRO [GM 7.0] e AS 3797 IPRO [GM 7.9] na primeira safra, e TEC 7849 IPRO e Brasmax Desafio RR [GM 7.4] na segunda safra). Os experimentos foram implantados na área da Cooperativa Agropecuária do Alto Paranaíba (Coopadap) no período de outubro de 2016 a março de 2018. Os experimentos foram conduzidos em esquema fatorial, sendo que nas duas safras foram utilizados seis tratamentos (Controle, Citocinina, Lactofen, Imazetapir, 2,4-D e Clorimuron) com quatro repetições. As parcelas experimentais foram constituídas de cinco linhas de sete metros com espaçamento de 0,6 m entre linhas. As aplicações ocorreram no estádio de desenvolvimento V3 utilizando pulverizador costal propelido a CO2. Foram realizadas avaliações (i) bioquímicas (atividade das enzimas superóxido dismutase, catalase e peroxidase, bem como teor de peróxido de hidrogênio e peroxidação lipídica) aos sete dias após a aplicação dos tratamentos, (ii) fenométricas (massa de matéria seca de haste, folha e vagem, número de nós e ramificações, número de vagens - apenas no segundo ano de experimentação) no estádio de desenvolvimento R6, e (iii) componentes de produção (produtividade). Os dados foram submetidos a testes de normalidade (Shapiro-Wilk) e homogeneidade (Levene), à análise de variância (análise fatorial) e, quando significativa, ao teste de Tukey (nível de significância de 5%). Com base nos resultados obtidos, concluiu-se que: (i) a aplicação dos tratamentos aumentou a produtividade (no tratamento com aplicação de Lactofen, principalmente); (ii) há ocorrência de dano fisiológico às plantas; entretanto, a intensidade pode variar com o material genético e as condições climáticas; e (iii) não há padrão de resposta entre as variedades cultivadas utilizadas. / The increase in world soybean consumption calls for the use of new technologies in its production system. One of these technologies is the change of architecture of the plant through the application of growth regulators. However, these products can cause damage to the plant. In this context, the objective was to identify oxidative metabolism damage in soybean plants treated with growth regulators (hormone and herbicides in subdose) and to verify the presence of a response pattern among cultivars of the maturation group (GM) 7.X (GM) the cultivars TEC 7849 IPRO [GM 7.0] and AS 3797 IPRO [GM 7.9] were used in the first harvest, and TEC 7849 IPRO and Brasmax Challenge RR [GM 7.4] in the second harvest. The experiments were carried out in the area of the Cooperativa Agropecuária do Alto Paranaíba (Coopadap) from October 2016 to March 2018. The experiments were conducted in a factorial scheme, and in the two harvests six treatments were used (Control, Cytokinin, Lactofen, Imazethapyr, 2,4-D and Chlorimuron) with four replicates. The experimental plots consisted of five seven - meter rows with spacing of 0.6 m between rows. The applications occurred at the V3 development stage using CO2 propellant sprayer. Biochemical evaluations (activity of the enzymes superoxide dismutase, catalase and peroxidase, as well as hydrogen peroxide content and lipid peroxidation) were carried out seven days after the application of the treatments, (ii) phenometric (stem dry matter mass, leaf and pod, number of nodes and branches, number of pods - only in the second year of experimentation) at the R6 development stage, and (iii) production components (productivity). Data were submitted to normality tests (Shapiro-Wilk) and homogeneity (Levene), analysis of variance (factorial analysis) and, when significant, Tukey test (significance level 5%). Based on the results obtained, it was concluded that: (i) the application of the treatments increased the productivity (in the treatment with application of Lactofen, mainly); (ii) there is occurrence of physiological damage to plants; however, the intensity may vary with genetic material and climatic conditions; and (iii) there is no pattern of response among the cultivated varieties used.

In an effort to maximize yields, many soybean growers have begun moving to intensive, input-based soybean management systems. However, limited reliable information exists about the effect of these inputs on soybean yield. The purpose of this study was to evaluate the effect of individual inputs and combinations of inputs as part of high-yield management systems on soybean seed yield and to determine the effect of one of these inputs, lactofen, on soybean physiology. Small plot studies were established in nine states across the Midwest. A number of commercially available soybean inputs were evaluated individually and in combination to determine their effect on soybean yield and quality. Lactofen and comparison treatments were applied to soybeans at multiple growth stages and yield and yield components were determined. When examined across environments, input-intensive combination treatments increased soybean yields from 3.9 to 8.1 %. However, break-even economic analysis indicated that the combination (SOYA) treatments evaluated had 0% probability of breaking across a wide range of yield levels and soybean prices, due to the high input costs. The foliar insecticide showed the highest probability of breaking even across a range of yield levels and crop prices (40% to 99%). Yield increases and breakeven probabilities were generally greatest in the northern states (Minnesota, Wisconsin, Michigan) and similar in the central and southern states. Lactofen application did not kill the apical meristem and had minimal effect on yield components compared to untreated soybeans at any growth stage. Meristem removal increased node m-2 in some environments, but did not increase pods m-2 and seeds m-2 or seed yield.

Made available in DSpace on 2014-06-11T19:34:57Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-02-13Bitstream added on 2014-06-13T19:44:38Z : No. of bitstreams: 1 correa_mjp_dr_jabo.pdf: 913272 bytes, checksum: 5000bc011ba683f81e165123412cb4d8 (MD5) / Uema-Universidade Estadual do Maranhao / O presente estudo teve por objetivo avaliar a eficácia e seletividade de herbicidas aplicados em pós-emergência, isolados e em misturas, para o controle de plantas daninhas e os efeitos sobre o crescimento e o desenvolvimento da soja convencional (M-SOY 8001) e transgênica (M-SOY 7908 RR). Também foram estudados os efeitos dos produtos sobre a atividade fotossintética e nas características morfológicas externas e internas das plantas. Foram conduzidos dois experimentos, no ano agrícola 2006/2007 e repetido em 2007/2008, em condições de campo, na Fazenda de Ensino, Pesquisa e Produção da UNESP, Câmpus de Jaboticabal, SP. O delineamento experimental utilizado foi em blocos ao acaso com quatro repetições. Os tratamentos constaram da aplicação de herbicidas isolados e em misturas: lactofen (168 g ha- 1), glyphosate (1080 g ha-1), lactofen + chlorimuron-ethyl (96 + 10 g ha-1), chlorimuron-ethyl + imazethapyr (10 + 70 g ha-1), chlorimuron-ethyl + bentazon (10 + 600 g ha-1), glyphosate + imazethapyr (900 + 70 g ha-1), lactofen + chlorimuronethyl + imazethapyr (96 + 10 + 70 g ha-1) e lactofen + chlorimuron-ethyl + imazethapyr/haloxyfop-methyl (96 + 10 + 70 / 60 g ha-1). Além disso, foram mantidas duas testemunhas sem aplicação de herbicida (capinada e mantida infestada). Concluiu-se que os herbicidas utilizados foram seletivos para a soja; exceção dos tratamentos com glyphosate na soja M-SOY 8001. Na condição de baixa infestação de plantas daninhas, os herbicidas aplicados foram eficazes no controle destas. Na área com maior infestação de plantas daninhas, a aplicação de glyphosate isolado ou em mistura com imazethapyr proporcionou melhor controle das plantas infestantes. Quanto a eficiência fotossintética máxima, apenas o cultivar convencional foi suscetível à aplicação dos herbicidas, principalmente às misturas contendo lactofen + chlorimuron-ethyl... / This research was carried out to evaluate the efficiency and selectivity postemergence herbicides applied alone and in mixtures to the weed control and the effects on the growth and the development transgenic (M-SOY 7908 RR) and conventional (M-SOY 8001) soybean. The effects of the products on the photosynthetic activity and the external and internal morphologic characteristics of the plants, also it studied. Two experiments were carried out from 2006/2007 and 2007/2008 under field conditions on Education, Research and Production Farm of UNESP in Jaboticabal, SP, Brazil. A randomized complete block experimental design with four replications was used. Herbicide treatments consisted lactofen (168 g ha-1), glyphosate (1080 g ha-1), lactofen + chlorimuronethyl (96 + 10 g ha-1), chlorimuron-ethyl + imazethapyr (10 + 70 g ha-1), chlorimuron-ethyl + bentazon (10 + 600 g ha-1), glyphosate + imazethapyr (900 g + 70 g ha-1), lactofen + chlorimuron-ethyl + imazethapyr (96 + 10 + 70 g ha-1) and lactofen + chlorimuron-ethyl + imazethapyr/haloxyfop-methyl (96 + 10 + 70 + 60 g ha-1). The tests included two nontreated (no hand weeded and hand weeded). The herbicides were selective for the soybean; exception of the treatments glyphosate applied in the M-SOY 8001 soybean. Under low weed condition, the herbicides applied were effective in the weed control. In the area with larger weed condition, glyphosate applied alone and glyphosate plus imazethapyr caused better control the weeds compared other herbicides. With respect to maximum photosynthetic efficiency response, just conventional soybean was susceptible the herbicides applied, mainly the mixtures containing lactofen + chlorimuron-ethyl and lactofen + chlorimuron-ethyl + imazethapyr / haloxifop-methyl. For total chlorophyll response, the varieties presented susceptibility to the lactofen alone and in mixture with chlorimuron-ethyl, imazethapyr... (Complete abstract click electronic access below)

The continued spread of Palmer amaranth (Amaranthus palmeri S. Wats.) throughout the southern and midwestern United States is a result of herbicide-resistant populations. Besides being the most troublesome weed specie in several agronomic crops, Palmer amaranth is also host to economically important pests such as tarnished plant bug (Lygus lineolaris Palisot de Beauvois). Pesticide application methodology that maximizes efficacy while reducing selection pressure is needed to combat herbicide-resistant Palmer amaranth. Pulse width modulation (PWM) sprayers are used for pesticide application with the goal of maintaining product efficacy while mitigating spray drift. Additionally, alternative off-season weed management practices such as flooding could be adopted to optimize soil seedbank depletion. Therefore, evaluation of spray droplet size and flooding period on Palmer amaranth control and seed germination was conducted. The objectives of this research were to: (1) evaluate the influence of spray droplet size on lactofen and acifluorfen efficacy on Palmer amaranth using a PWM sprayer, (2) develop prediction models to determine spray droplet size that provides the greatest level of Palmer amaranth control, (3) evaluate the impact of flooding period and seed burial depth on Palmer amaranth seed germination in different soil textures, and (4) analyze the impact of nitrogen fertilizer application rate on the attractiveness of Palmer amaranth to tarnished plant bug. Results show that spray droplet size does not affect lactofen efficacy on Palmer amaranth, thus, coarser spray droplets are recommended to increase spray drift mitigation efforts. In contrast, acifluorfen applied with 300 μm (medium) spray droplets provided the greatest Palmer amaranth control. Furthermore, prediction models indicated that greater model accuracy was obtained when adopting a location-specific weed management approach. Flooding periods of 3, 4, and 5 months reduced Palmer amaranth seed germination across burial depths and soil textures. Therefore, fall-winter flooding may be adopted as an effective practice for soil seedbank depletion. Results also demonstrated that nitrogen fertilizer application rate does not consistently impact Palmer amaranth attractiveness to tarnished plant bug.