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Teuton, Travis C., J. Bryan Unruh, Barry J. Brecke, Greg E. Macdonald, Grady L. Miller y Joyce Tredaway Ducar. "Tropical Signalgrass (Urochloa subquadripara) Control with Preemergence- and Postemergence-Applied Herbicides". Weed Technology 18, n.º 2 (junio de 2004): 419–25. http://dx.doi.org/10.1614/wt-03-155r1.
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Tropical signalgrass is one of the most serious weed problems in the St. Augustinegrass sod production in Florida, and its presence increases production costs and lowers turfgrass quality. The objectives of our research were to: (1) evaluate herbicides preemergence and postemergence for control of tropical signalgrass and (2) compare control of tropical signalgrass and other problem weeds (torpedograss, blanket crabgrass, and India crabgrass) with postemergence herbicides. In preemergence herbicide field trials, only benefin + oryzalin, imazapic, imazapic + 2,4-D, and oryzalin provided ≥75% tropical signalgrass control 8 wk after application (WAA). By 11 WAA, only benefin + oryzalin and imazapic + 2,4-D provided ≥75% tropical signalgrass control. In greenhouse experiments, eight herbicide treatments were applied postemergence to tropical signalgrass seedlings at the two-, four-, six-, and eight-leaf stages. Asulam and CGA 362622 provided ≥89% tropical signalgrass control at all application timings. Imazaquin controlled tropical signalgrass ≥98% when applied before the eight-leaf stage. However, in field trials with mature tropical signalgrass (>20 cm stolons), none of the 20 herbicide treatments applied postemergence provided acceptable control.
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Mueller, Thomas C. y Robert M. Hayes. "Effect of Tillage and Soil-Applied Herbicides on Broadleaf Signalgrass (Brachiaria platyphylla) Control in Corn (Zea mays)". Weed Technology 11, n.º 4 (diciembre de 1997): 698–703. http://dx.doi.org/10.1017/s0890037x00043281.
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Broadleaf signalgrass control from preemergence (PRE) herbicides was usually lower in no-till than in tilled plots. Broadleaf signalgrass control was most nearly complete in tilled plots treated with metolachlor in 1995, a year that favored an herbicide with more soil persistence. Broadleaf signalgrass control was most nearly complete in tilled plots treated with acetochlor in 1996, a year in which rainfall to activate the herbicides did not occur until 9 d after planting. The 1996 data indicated that acetochlor was more stable on the soil surface under the drier conditions. There was no difference in broadleaf signalgrass control between the two acetochlor formulations. Alachlor, metolachlor, and dimethenamid controlled broadleaf signalgrass > 80% for about 4 wk, acetochlor provided control for about 4 wk under no-till conditions and about 8 wk in tilled plots, and pendimethalin provided about 2 wk broadleaf signalgrass control. Acetochlor provided consistent control regardless of the rainfall pattern after application.
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Gallaher, Kent, Thomas C. Mueller, Robert M. Hayes, Otto Schwartz y Michael Barrett. "Absorption, translocation, and metabolism of primisulfuron and nicosulfuron in broadleaf signalgrass (Brachiaria platyphylla) and corn". Weed Science 47, n.º 1 (febrero de 1999): 8–12. http://dx.doi.org/10.1017/s0043174500090585.
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Broadleaf signalgrass is sensitive to nicosulfuron and resistant to primisulfuron, but corn is resistant to both. Research was conducted to determine the effect of varying light level and air temperature on absorption, translocation, and metabolism of nicosulfuron and primisulfuron in broadleaf signalgrass and corn. Corn absorbed between 60 and 85% of the applied nicosulfuron and primisulfuron within 72 h after treatment (HAT), depending on environmental treatment. Absorption, translocation, and metabolism all tended to be more rapid at higher temperature and light intensity. Nicosulfuron and primisulfuron translocation out of the treated leaf was < 4.5% of herbicide absorbed through 72 HAT. Corn rapidly metabolized both herbicides in both environments. However, primisulfuron was metabolized more rapidly (high = 99%, low = 92%) than nicosulfuron (high = 95%, low = 78%). Broadleaf signalgrass absorbed 20% more nicosulfuron than primisulfuron through 72 HAT. Nicosulfuron translocation out of the treated leaf in broadleaf signalgrass was ≤ 15% absorbed through 72 HAT, while primisulfuron translocation was ≤ 4% during the same time period. Primisulfuron metabolism was more rapid than nicosulfuron in broadleaf signalgrass. During the first 4 HAT, broadleaf signalgrass metabolized > 20 times more primisulfuron than nicosulfuron. By 72 HAT, broadleaf signalgrass under conditions of high light and temperature had metabolized nearly 90% of the primisulfuron absorbed but ≤ 7% of the nicosulfuron absorbed was metabolized during the same time. These results suggest that differential activity of nicosulfuron and primisulfuron on broadleaf signalgrass may be based on differential rates of metabolism to nonphytotoxic compounds; uptake and translocation differences agree with the differential broadleaf signalgrass activity. Additionally, environment has the potential to affect rates of sulfonylurea absorption, translocation, and metabolism.
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McGregor, John T., Roy J. Smith y Ronald E. Talbert. "Interspecific and Intraspecific Interference of Broadleaf Signalgrass (Brachiaria platyphylla) in Rice (Oryza sativa)". Weed Science 36, n.º 5 (septiembre de 1988): 589–93. http://dx.doi.org/10.1017/s0043174500075457.
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Field experiments were conducted in 1984 and 1985 at Stuttgart, AR, to investigate the interspecific and intraspecific interference of broadleaf signalgrass densities of 0, 10, 50, 100, and 150 plants/m2with rice. In 1984, significant reductions in rice leaf area index (LAI) occurred 6 weeks after emergence with all broadleaf signalgrass densities. The first reduction in LAI occurred 8 weeks after emergence at the density of 150 plants/m2in 1985. Densities of 50 plants/m2or greater reduced rice dry weight 6 weeks after emergence in 1984, and the highest density of 150 plants/m2reduced rice dry weight 12 weeks after emergence in 1985. Height of rice was reduced by densities of 100 and 150 plants/m2. Linear regression equations indicated that each broadleaf signalgrass plant/m2reduced rough rice yield 18 kg/ha both years. Growth of broadleaf signalgrass was reduced by interspecific and intraspecific interference. The dry weight of broadleaf signalgrass increased at a decreasing rate at plant densities of 100 to 150/m2when grown alone in 1984 and 1985, when a quadratic equation best described the response. Regression equations indicated interspecific interference from rice reduced broadleaf signalgrass dry weight an average of 48 and 81% in 1984 and 1985, respectively. The height of broadleaf signalgrass was greater when grown with rice than when grown alone.
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Corkern, Christopher B., David L. Jordan, James L. Griffin, P. Roy Vidrine, Bill J. Williams y Daniel B. Reynolds. "Influence of Adjuvants on Interactions of Sethoxydim with Selected Broadleaf Herbicides Used in Corn (Zea mays)". Weed Technology 13, n.º 4 (diciembre de 1999): 821–24. http://dx.doi.org/10.1017/s0890037x00042287.
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Field experiments were conducted during 1996 and 1998 to determine the effect of atrazine, bentazon, atrazine + bentazon, the amine salt of 2,4-D, and bromoxynil on broadleaf signalgrass and barnyardgrass control when applied in mixture with sethoxydim. Herbicide combinations were applied with crop oil concentrate, crop oil concentrate + ammonium sulfate, or BCH 815. Bentazon and atrazine + bentazon reduced broadleaf signalgrass and barnyardgrass control by sethoxydim. Bromoxynil reduced barnyardgrass control but had no affect on broadleaf signalgrass control. Including ammonium sulfate with crop oil concentrate or substituting BCH 815 for crop oil concentrate increased barnyardgrass and broadleaf signalgrass control by sethoxydim when applied with bentazon. Ammonium sulfate and BCH 815 increased barnyardgrass control when sethoxydim was applied with bromoxynil but did not affect control when sethoxydim was applied with atrazine + bentazon. Atrazine and the ammonium salt of 2,4-D did not reduce barnyardgrass and broadleaf signalgrass control by sethoxydim regardless of adjuvant.
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FERREIRA, G. L., D. T. SARAIVA, G. P. QUEIROZ, D. V. SILVA, G. A. M. PEREIRA, L. R. FERREIRA, S. N. OLIVEIRA NETO y E. M. MATTIELLO. "Eucalypt Growth Submitted to Management of Urochloa spp." Planta Daninha 34, n.º 1 (marzo de 2016): 99–107. http://dx.doi.org/10.1590/s0100-83582016340100010.
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The objective of this work was to evaluate the initial growth and the physiological characteristics of eucalypt submitted to different managements of signalgrass. The experiment was conducted in a protected environment, using a randomized blocks design with five repetitions. The treatments were arranged in a (5 x 2) + 1 factorial design, and the first factor corresponded to the types of weed management (no control; chemical control keeping the signalgrass shoot on the soil; chemical control with removal of the signalgrass shoot; mechanical control keeping the signalgrass shoot on the soil, and mechanical control with removal of the signalgrass shoot); the second factor corresponded to the two weeds species (U. brizantha and U. decumbens) and a control relative to the eucalypt in monoculture. The eucalypt growth was not affected by the presence of the Urochloa species until 50 days after treatments (DAT). However, the coexistence of these species with eucalypt for 107 DAT reduced the collar diameter, total dry matter, and the leaf area, but did not alter the characteristics related to photosynthesis and transpiration. The control method adopted, with removal or maintenance of the signalgrass shoot, regardless of species, did not change the initial eucalypt growth. It can be concluded that the coexistence of eucalypt with Urochloa decumbens or Urochloa brizantha for 105 days reduces the eucalypt growth. However, the use of chemical or mechanical control, with or without removal of signalgrass residue, were effective methods to prevent interference of these weeds.
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da Silva, Izabela Aline Gomes, Jose Carlos Batista Dubeux, Alexandre C. Leão de Mello, Márcio Vieira da Cunha, Mércia Ferreira dos Santos, Valéria Oliveira Apolinário, Gleise Medeiros da Silva, Erinaldo Viana de Freitas y Nicolas DiLorenzo. "6 Animal performance in grass monoculture or silvopasture systems using tree legumes". Journal of Animal Science 98, Supplement_2 (1 de noviembre de 2020): 18–19. http://dx.doi.org/10.1093/jas/skz397.041.
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Abstract Silvopasture systems (SPS) area management option to enhance delivery of ecosystem services and diversification of income. This study evaluated productive responses of signalgrass (UrochloadecumbensStapf.) in monoculture or in SPS in the sub-humid tropical region of Brazil during six months of the rainy season. The experimental design was randomized complete block with three replications. Treatments were signalgrass + Mimosa caesalpiniifolia Benth. (SPS-Mimosa); signalgrass + Gliricidia sepium (Jacq.) (SPS-Gliricidia); and signalgrass monoculture. Cattle were managed under continuous stocking with variable stocking rate. Response variables included herbage mass (HM), herbage accumulation (HA), stocking rate (SR), average daily gain (ADG), and gain per area (GPA). Herbage mass (HM) was greater (P < 0.0001) on signal grass monoculture (2045 kg DM/ha) than in SPS (1370 kg DM/ha, average for both SPS). Herbage accumulation rate was similar for signalgrass in monoculture and SPS-Gliricidia (avg. 61 kg DM ha-1 d-1), and both were greater than SPS-Mimosa (37 kg DM ha-1 d-1). Average daily gain was greater(P < 0.0001) for SPS-Gliricidia (1.1 kg head-1 d-1), followed by signalgrass in monoculture (0.9 kg head-1 d-1), and SPS-Mimosa (0.3 kg head-1 d-1). Stocking rate ranged from 0.6 animal units (1AU = 450-kg animal) per ha in April to 2.2 AUha-1 in June. Stocking rate and animal performance per area were similar for signalgrass in monoculture and SPS-Gliricidia, and both greater than SPS-Mimosa. Gliricidia enhanced animal performance and provided ecosystem services. Mimosa, however, reduced animal performance likely due to the competition with signalgrass. Mimosa trees, however, are an important source of income (timber used for fence posts) and that might overcome the losses in animal performance.
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da Silva, Izabela Aline Gomes, Jose Carlos Batista Dubeux, Alexandre C. Leão de Mello, Márcio Vieira da Cunha, Mércia Ferreira dos Santos, Valéria Oliveira Apolinário, Gleise Medeiros da Silva, Erinaldo Viana de Freitas y Nicolas DiLorenzo. "5 Animal performance in grass monoculture or silvopasture systems using tree legumes". Journal of Animal Science 98, Supplement_2 (1 de noviembre de 2020): 27–28. http://dx.doi.org/10.1093/jas/skz397.062.
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Abstract Silvopasture systems (SPS) area management option to enhance delivery of ecosystem services and diversification of income. This study evaluated productive responses of signalgrass (Urochloadecumbens Stapf.) in monoculture or in SPS in the sub-humid tropical region of Brazil during six months of the rainy season. The experimental design was randomized complete block with three replications. Treatments were signalgrass + Mimosa caesalpiniifolia Benth. (SPS-Mimosa); signalgrass + Gliricidia sepium (Jacq.) (SPS-Gliricidia); and signalgrass monoculture. Cattle were managed under continuous stocking with variable stocking rate. Response variables included herbage mass (HM), herbage accumulation (HA), stocking rate (SR), average daily gain (ADG), and gain per area (GPA). Herbage mass (HM) was greater (P < 0.0001) on signal grass monoculture (2045 kg DM/ha) than in SPS (1370 kg DM/ha, average for both SPS). Herbage accumulation rate was similar for signalgrass in monoculture and SPS-Gliricidia (avg. 61 kg DM ha-1 d-1), and both were greater than SPS-Mimosa (37 kg DM ha-1 d-1). Average daily gain was greater(P < 0.0001) for SPS-Gliricidia (1.1 kg head-1 d-1), followed by signalgrass in monoculture (0.9 kg head-1 d-1), and SPS-Mimosa (0.3 kg head-1 d-1). Stocking rate ranged from 0.6 animal units (1AU = 450-kg animal) per ha in April to 2.2 AUha-1 in June. Stocking rate and animal performance per area were similar for signalgrass in monoculture and SPS-Gliricidia, and both greater than SPS-Mimosa. Gliricidia enhanced animal performance and provided ecosystem services. Mimosa, however, reduced animal performance likely due to the competition with signalgrass. Mimosa trees, however, are an important source of income (timber used for fence posts) and that might overcome the losses in animal performance.
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Grichar, W. J., B. A. Besler, K. D. Brewer y T. A. Baughman. "Grass Control in Peanut (Arachis hypogaea) with Clethodim and Selected Broadleaf Herbicide Combinations1". Peanut Science 29, n.º 2 (1 de julio de 2002): 85–88. http://dx.doi.org/10.3146/pnut.29.2.0002.
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Abstract Field studies were conducted to evaluate broadleaf signalgrass and southern crabgrass control and effect on peanut yield of clethodim alone and sequential applications with six broadleaf herbicides. When rated 9 wk after treatment (WAT), broadleaf signalgrass control with clethodim followed by (fb) acifluorfen, imazapic, or 2,4-DB 24 hr later did not differ from clethodim alone. When acifluorfen, acifluorfen plus bentazon, imazethapyr, imazapic, and lactofen were applied in a tank-mix with clethodim, broadleaf signalgrass control was less than 65%. Clethodim alone or clethodim plus 2,4-DB controlled 86 and 73% broadleaf signalgrass, respectively. When acifluorfen, acifluorfen plus bentazon, or imazethapyr was fb clethodim, signalgrass control was less than 72%. Southern crabgrass control was reduced in 2 of 3 yr from clethodim alone when acifluorfen was tank-mixed with clethodim. When other broadleaf herbicides were tank-mixed with clethodim, reduced crabgrass control was noted in only 1 of 3 yr. Where no POST herbicides were used, peanut yield was < 1600 kg/ha, while all plots which received a POST herbicide yielded over 2200 kg/ha.
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Johnson, W. Carroll y Harold D. Coble. "Crop Rotation and Herbicide Effects on the Population Dynamics of Two Annual Grasses". Weed Science 34, n.º 3 (mayo de 1986): 452–56. http://dx.doi.org/10.1017/s0043174500067187.
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A 3-yr study was initiated in 1982 to determine the effects of herbicides and crop rotations on large crabgrass [Digitaria sanguinalis(L.) Scop. # DIGSA] and broadleaf signalgrass [Brachiaria platyphylla(Griseb.) Nash # BRAPP] population dynamics. Regardless of the crop rotation sequence, broadleaf signalgrass immediately became the predominant weed where standard herbicide programs were used. Large crabgrass became the predominant species after two growing seasons if no herbicides were applied. Domination by large crabgrass appeared to be due to greater seed production. The domination by broadleaf signalgrass in plots treated with herbicides was attributed to its tolerance to the primary grass herbicide alachlor [2-chloro-N-(2,6-diethylphenyl)-N-methoxymethyl)acetamide]. Broadleaf signalgrass emergence from soil treated with 2.2 kg ai/ha was not statistically different from that in untreated soil, while large crabgrass and fall panicum [Panicum dichotomiflorum(L.) Michx. # PANDI] emergence was significantly reduced at the same rate.
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Suryanto, Priyono, Eny Faridah, Ananto Triyogo, Dody Kastono, Bambang Suwignyo, Aprilia Ike Nurmalasari y Taufan Alam. "Designing soil quality and climate assessment tool for sustainable production of signalgrass (Brachiaria brizantha) silvopasture system in mountain ecosystems". April 2020, n.º 14(04):2020 (20 de abril de 2020): 614–21. http://dx.doi.org/10.21475/ajcs.20.14.04.p2147.
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Evironmental indicators are the elements required to plan sustainable forest management practices. This assessment was carried out based on indicators that are sensitive to management and changes in the soil, climate, and associated functions. This study aims at determining soil quality and climate that affect the production of signalgrass silvopasture system in mountain ecosystems. The survey-based study was conducted during dry and wet seasons in 2017-2018. We used stratified random sampling method. Stratification was based on site (agroforestry phase) and environment (season and year). Site nested on environment. Agroforestry phases consisted of initial phase (<50% of the shade intensity of the sun), intermediate phase (50-70% of the shade intensity of the sun), and advanced phase (>70% of the shade intensity of the sun). Seasons were divided into two, dry season (rainfall < 60 mm.month-1) and wet season (rainfall > 100 mm.month-1) and years were limited from 2017 to 2018. The observation was conducted on 30 environmental parameters and signalgrass productions. The data was analyzed using linear mixed models, analysis of variance (ANOVA), structural equation modelling (SEM), and stepwise regression. The study results indicate that the highest signalgrass production at the initial agroforestry phase was 4.50 tons.ha-1. There is a very significant decrease in signalgrass production at the intermediate agroforestry phase by 36.64 % and at the advanced agroforestry phase by 280.80 %, compared to the initial agroforestry phase. The signalgrass production was increased very significantly influenced by the increase in cation exchange capacity (CEC), soil organic carbon (SOC), air temperature (Tair), and wind speed (U2). In addition, it was also significantly influenced by available nitrate (NO3-). Signalgrass production can be improved by the assessment tools by improving CEC, NO3-, SOC, U2 , and Tair with routine organic matters application and annual pruning.
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Gimenez, Agustin E., Alan C. York, John W. Wilcut y Roger B. Batts. "Annual Grass Control by Glyphosate plus Bentazon, Chlorimuron, Fomesafen, or Imazethapyr Mixtures". Weed Technology 12, n.º 1 (marzo de 1998): 134–36. http://dx.doi.org/10.1017/s0890037x0004269x.
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The isopropylamine salt of glyphosate at 420, 560, and 840 g ae/ha applied alone or mixed with the sodium salt of bentazon at 840 g ai/ha, chlorimuron at 9 g ai/ha, the sodium salt of fomesafen at 350 g ai/ha, or the ammonium salt of imazethapyr at 70 g ae/ha was evaluated for control of large crabgrass and broadleaf signalgrass. Neither grass was controlled by bentazon, fomesafen, or chlorimuron. Imazethapyr controlled large crabgrass and broadleaf signalgrass 30 and 72%, respectively, 3 weeks after treatment (WAT). Glyphosate at all rates controlled both grasses 100%. Control 3 WAT was unaffected by mixing bentazon, chlorimuron, fomesafen, or imazethapyr with glyphosate. Broadleaf signalgrass control 1 WAT was reduced 4 to 15% by mixing bentazon with glyphosate.
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Lancaster, Sarah H., David L. Jordan y P. Dewayne Johnson. "Influence of Graminicide Formulation on Compatibility with Other Pesticides". Weed Technology 22, n.º 4 (diciembre de 2008): 580–83. http://dx.doi.org/10.1614/wt-07-067.1.
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Experiments were conducted from 2003 through 2006 to compare annual grass control by graminicides applied alone or with other pesticides and to determine whether graminicide formulation affected annual grass control and interactions with co-applied pesticides. Formulation and rate had no affect on broadleaf signalgrass or large crabgrass control by clethodim. The efficacy of clethodim in tank mixtures with acifluorfen plus bentazon, bentazon, chlorothalonil, imazapic, pyraclostrobin, or tebuconazole were not affected by clethodim formulation. Broadleaf signalgrass and large crabgrass control by clethodim was slightly reduced by acifluorfen plus bentazon, chlorothalonil, imazapic, and pyraclostrobin, but not by tebuconazole. Chlorothalonil and pyraclostrobin reduced broadleaf signalgrass control with quizalofop-P but did not reduce fall panicum control. Azoxystrobin, propiconazole, and tebuconazole did not affect efficacy of quizalofop-P.
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SILVA, D. V., M. A. M. FREITAS, M. F. SOUZA, G. P. QUEIROZ, C. A. D. MELO, A. A. SILVA, L. R. FERREIRA y M. R. REIS. "Glyphosate Herbicide Use in Urochloa brizantha Management in Intercropping With Herbicide-Resistant Maize". Planta Daninha 34, n.º 1 (marzo de 2016): 133–41. http://dx.doi.org/10.1590/s0100-83582016340100014.
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The success of the intercropping among cultivated species depends on the adoption of practices that provide, in due course, greater competitive ability of a species over another. The objective of this study was to evaluate the use of glyphosate herbicide in the suppression of Brachiaria (signalgrass) intercropped with maize. The experiment was conducted in a randomized complete block design with four replications. The treatments were arranged in a 5 x 2 + 2 factorial arrangement, the first factor corresponding to the doses of glyphosate (48, 96, 144, 240, 480 g ha-1 of the acid equivalent (a.e)) and the second one to the vegetative stages of the signalgrass at the time of application (2 and 4 tillers). Two controls were added to the treatment list, comprising controls without herbicide application and hand removal of the signalgrass. The number of plants, tillers and dry matter of signalgrass was reduced with glyphosate. The increase of the glyphosate doses enhanced the injure to the forage plants, mainly when the compound was sprayed at the two-tiller vegetative stage. The dry matter of maize plants increased proportionally to the glyphosate dose. However, the height of the maize plants was not affected. The grain mass and productivity of maize grain increased with increasing dose of glyphosate. The maize yield was negatively influenced on the untreated control. Glyphosate at 96 and 144 g ha-1, when applied at 2 and 4 tiller stage, respectively, reduces the growth of signalgrass and does not affect the maize grain yield.
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Lancaster, Sarah H., David L. Jordan, Alan C. York, John W. Wilcut, David W. Monks y Rick L. Brandenburg. "Interactions of Clethodim and Sethoxydim with Selected Agrichemicals Applied to Peanut". Weed Technology 19, n.º 2 (junio de 2005): 456–61. http://dx.doi.org/10.1614/wt-04-232r.
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Experiments were conducted in North Carolina during 2002 and 2003 to evaluate broadleaf signalgrass and large crabgrass control by clethodim and sethoxydim applied in two-, three-, or four-way mixtures with fungicides, insecticides, and foliar fertilizer–plant growth regulator treatments. Broadleaf signalgrass and large crabgrass control by clethodim and sethoxydim was not reduced by the insecticides esfenvalerate, indoxacarb, or lambda-cyhalothrin. The fungicides azoxystrobin, chlorothalonil, pyraclostrobin, and tebuconazole reduced large crabgrass control by clethodim or sethoxydim in one or more of three experiments for each herbicide. Disodium octaborate and the plant growth regulator prohexadione calcium plus urea ammonium nitrate (UAN) mixed with clethodim and fungicides improved large crabgrass control in some experiments. In contrast, prohexadione calcium plus UAN and disodium octaborate did not affect broadleaf signalgrass or large crabgrass control by sethoxydim.
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Dias, Renan Coelho, Márcia Vitória Santos, Fabiana Lopes Ramos de Oliveira, Evander Alves Ferreira, José Barbosa dos Santos, Bárbara Martins Rodrigues y Cézar Augusto Martins. "Chemical control of signalgrass in alfalfa crops". Semina: Ciências Agrárias 38, n.º 6 (23 de noviembre de 2017): 3695. http://dx.doi.org/10.5433/1679-0359.2017v38n6p3695.
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The use of herbicides to control grass in Medicago sativa (alfalfa) pastures is still incipient. Therefore, the objective of this study was to evaluate the efficiency of fluazifop-p-butyl in the control of Brachiaria decumbens (signalgrass) in alfalfa. Thus, randomized block design was used, with seven doses of fluazifop-p-butyl (0, 25, 50, 100, 200, 300, 400 g ha-1), and four replications. Herbicide application was performed when the plants had about 20 cm height. Chlorophyll fluorescence, control of signalgrass and alfalfa toxicity were evaluated at 7, 15 e 30 days after application (DAA) and, at 45 DAA and 45 days after cut (DAC), both species were cut and tiller density, as well as branches and dry matter of forage species, were determined. Fluazifop-p-butyl does not affect the integrity of the photosynthetic apparatus of alfalfa plants, due to high tolerance to this mechanism of action presented by dicotyledonous species. However, signalgrass had physiological variables negatively affected by the herbicide, indicating the presence of physiological stress, even at the lowest doses of the product. The dose of 50 g ha-1 of fluazifop-p-butyl is effective in controlling signalgrass, without causing physiological and growth damage in alfalfa plants.
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Stephenson, Daniel O., Jason A. Bond, Eric R. Walker, Mohammad T. Bararpour y Lawrence R. Oliver. "Evaluation of Mesotrione in Mississippi Delta Corn Production". Weed Technology 18, n.º 4 (diciembre de 2004): 1111–16. http://dx.doi.org/10.1614/wt-03-260r1.
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Field studies were conducted in Arkansas in 1999, 2000, and 2001 to evaluate mesotrione applied preemergence (PRE) and postemergence (POST) for weed control in corn grown in the Mississippi Delta region of the United States. Mesotrione was applied PRE (140, 210, and 280 g/ha) alone and POST (70, 105, and 140 g/ha), alone or in tank mixtures with atrazine (280 g/ha). Standard treatments for comparison were S-metolachlor/atrazine PRE and S-metolachlor plus atrazine PRE followed by atrazine POST. All PRE treatments controlled velvetleaf, pitted morningglory, entireleaf morningglory, prickly sida, and broadleaf signalgrass 95% 2 wk after emergence (WAE). Mesotrione controlled velvetleaf 89% or more 4 and 6 WAE. Control of morningglory species by mesotrione POST averaged 92% 6 WAE. Prickly sida was controlled at least 90% by all treatments 4 WAE. Mesotrione applied alone PRE and POST controlled broadleaf signalgrass 83 to 91% 4 WAE. All treatments controlled broadleaf signalgrass less than 90% 6 WAE, except treatments that contained S-metolachlor, which gave 94% or greater control. Corn yield ranged from 10.5 to 12.4 Mg/ha and did not differ among treatments. Mesotrione PRE and POST provided excellent control of broadleaf weeds, but S-metolachlor was needed for broadleaf signalgrass control.
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Buehring, Nathan W., Ronald E. Talbert y Ford L. Baldwin. "Interactions of Graminicides with Other Herbicides Applied to Rice (Oryza sativa)". Weed Technology 20, n.º 1 (marzo de 2006): 215–20. http://dx.doi.org/10.1614/wt-04-263r.1.
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Three field experiments were conducted to evaluate efficacy of BAS 625, cyhalofop, and fenoxaprop plus isoxadifen when applied alone or with acifluorfen plus bentazon, acifluorfen, bentazon, triclopyr, bensulfuron, halosulfuron, carfentrazone, and propanil. Broadleaf signalgrass control with fenoxaprop plus isoxadifen was reduced by triclopyr and halosufuron. None of these herbicides reduced Amazon sprangletop control by fenoxaprop plus isoxadifen. Barnyardgrass control with fenoxaprop plus isoxadifen was reduced by halosulfuron and propanil. Barnyardgrass and Amazon sprangletop control by cyhalofop was reduced by bentazon plus acifluorfen, bentazon, acifluorfen, triclopyr, bensulfuron, or halosulfuron. Broadleaf signalgrass control with cyhalofop was reduced by triclopyr and halosulfuron. Amazon sprangletop control by cyhalofop was reduced by all herbicides. Barnyardgrass control with BAS 625 was reduced when applied with propanil, bentazon, or bentazon plus acifluorfen. Broadleaf signalgrass control with BAS 625 was reduced when applied with bentazon plus acifluorfen. Amazon sprangletop control with BAS 625 was reduced when applied with bentazon, acifluorfen, halosulfuron, or propanil.
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Alford, Jason L., Robert M. Hayes, G. Neil Rhodes, Lawrence E. Steckel y Thomas C. Mueller. "Broadleaf signalgrass (Brachiaria platyphylla) interference in corn". Weed Science 53, n.º 1 (enero de 2005): 97–100. http://dx.doi.org/10.1614/ws-04-092r.
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Lira, Carolina C., Jose C. B. Dubeux, Jr ,. Erick R. S. Santos, Mércia V. F. dos Santos y Erinaldo V. de Freitas. "Dung decomposition of cattle grazing from mixed pastures of Signalgrass (Brachiaria decumbens Stapf.) and tree legumes". DECEMBER 2019, n.º 13(12):2019 (20 de diciembre de 2019): 1943–49. http://dx.doi.org/10.21475/ajcs.19.13.12.p1494.
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The mineralization rate of ruminant manure may influence the fertilization management of pastures. This study aimed to evaluate feces decomposition of heifers grazing signalgrass (Brachiaria decumbens Stapf.) fertilized or not with N, or intercropped with legumes in the dry forest region. Two experiments were conducted; the first one was a CRD that evaluated the evolution of CO2 from a mixture of soil and feces (10:1) during 22 days of incubation in a hermetically sealed bucket with a solution of NaOH 0.5 mol L-1. The second one was a RCBD that evaluated the in situ decomposition of feces in nylon bags in time periods 4, 8, 16, 32, 64, 128 and 256 days after incubation above ground. The single negative exponential mathematical model was adequate (P ≤ 0.0001) to quantify the CO2 evolution of the mixture of soil and feces, indicating that 78% of CO2 was released at the beginning of the incubation, especially for the feces collected in the signalgrass pastures intercropped with Gliricidia sepium (Jacq.) Kunth ex Walp. (gliricídia). After the first 5 days, CO2 evolution was more stable. Remaining biomass in the litterbag along decomposition fitted the single negative exponential model (P < 0.001). Greater relative decomposition rate (k) of bovine fecal biomass occurred for the N-fertilized signalgrass treatment (k = 0.0031 g g-1 day-1) and a lesser rate for the treatment intercropped with Mimosa caesalpiniifolia Benth. (sabiá) (k = 0.0018 g g-1 day-1). Nitrogen fertilization in signalgrass pasture favored the decomposition of bovine feces at the end of 256 days of incubation.
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Rodrigues, Barbara Martins, Marcia Vitoria Santos, Josimari Regina Paschoaloto, Thiago Gomes dos Santos Braz, José Barbosa Santos, Cesar Augusto Martins, João Pedro Rodrigues Costa y Claudia Eduarda Borges. "Chemical control of signalgrass for establishing Tanzania-grass". Acta Scientiarum. Animal Sciences 42 (1 de abril de 2020): e48408. http://dx.doi.org/10.4025/actascianimsci.v42i1.48408.
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Herbicides have been used to control Brachiaria grass in pastures established or in formation given their practicality, however their efficiency is questionable due to the lack of specific graminicides for different forage species. Therefore, the goal of this study was to evaluate the efficiency of glyphosate and fluazifop-p-butyl in the control of Brachiaria decumbens (signalgrass) and the intoxication levels of Panicum maximum cv. Tanzania (Tanzania quinea grass) in pasture establishment. The experiments were designed in randomized blocks, in a 2 × 5 × 4 factorial arrangement of two herbicides (fluazifop-p-butyl and glyphosate), five doses equivalent to the commercial dosage of each herbicide (0.25; 0.50; 1.00; 1.50; 200), and four evaluation times after herbicide application (15, 21, 30 and 45 days). There was interaction between doses and evaluation times. The dose 1.5 L ha-1 fluazifop-p-butyl provides efficient control of signalgrass, however, leads to high intoxication in Tanzania guinea grass. Glyphosate is efficient in the control of signalgrass even at the lowest dose (90 g ha-1), however, it causes high intoxication in Tanzania guinea grass, preventing its use in developing pastures. It can be concluded that fluazifop-p-butyl and glyphosate herbicides are not recommended for the control of B. decumbens, cv. Basilisk in developing pastures of Tanzania guinea grass.
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Fuxa, J. R. "SEASONAL OCCURRENCE OF SPODOPTERA FRUGIPERDA LARVAE ON CERTAIN HOST PLANTS IN LOUISIANA1". Journal of Entomological Science 24, n.º 3 (1 de julio de 1989): 277–89. http://dx.doi.org/10.18474/0749-8004-24.3.277.
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The seasonal occurrence of fall army worm (FAW) larvae, [Spodoptera frugiperda (J. E. Smith)], was monitored weekly in corn [Zea mays L.], sorghum [Sorghum bicolor (L.)], signalgrass [Brachiaria decumbens Staph.], and bermudagrass [Cynodon dactylon (L.)] in southeastern Louisiana during 1980–84. The earliest and latest dates of detection of FAW during the study were, respectively, April 19 and August 4 for corn, June 9 and August 18 for sorghum, June 2 and September 21 for signalgrass, and June 8 and October 6 for bermudagrass. FAW generations overlapped in 1980, but in the other years generations were distinguishable and often coincided on the various host plants. The results indicated that there could be at least six generations in one year. In each year there was one major, and usually one or more minor, population peaks on each host plant. The range of dates for the greatest population peak density was June 24 - July 18 in corn, June 17 - July 7 in sorghum, June 30 - August 23 in signalgrass, and July 7 - August 18 in bermudagrass. The highest observed population density was ca. 3 × 105 larvae/ha in corn and 3 × 106 larvae/ha in bermudagrass.
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Silva, Arejacy Antônio Sobral, Dilermando Miranda da Fonseca, Manoel Eduardo Rozalino Santos, Bráulio Maia de Lana Sousa, Virgílio Mesquita Gomes y Reinaldo Bertola Cantarutti. "Initial height and nitrogen fertilization on deferred signalgrass". Bioscience Journal 31, n.º 6 (2015): 1671–81. http://dx.doi.org/10.14393/bj-v31n6a2015-26277.
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Pratt, R. G. "Johnsongrass, Yellow Foxtail, and Broadleaf Signalgrass as New Hosts for Six Species of Bipolaris, Curvularia, and Exserohilum Pathogenic to Bermudagrass". Plant Disease 90, n.º 4 (abril de 2006): 528. http://dx.doi.org/10.1094/pd-90-0528b.
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Johnsongrass (Sorghum halepense (L.) Pers.), broadleaf signalgrass (Brachiaria platyphylla (L.) Beauv.), and yellow foxtail (Setaria glauca L.) are common volunteer grasses in bermudagrass (Cynodon dactylon (L.) Pers.) pastures in the southeastern United States. Johnsongrass and broadleaf signalgrass are potential forages whereas yellow foxtail is a noxious weed. In 1999 and subsequent years, necrosis and dieback of leaves, stems, and roots, stunting, and plant death were observed on all three species in bermudagrass pastures in north Mississippi (3). Symptoms on johnsongrass and yellow foxtail were most severe where bermudagrass exhibited severe symptoms of infection caused by dematiaceous hyphomycetes (2,3); symptoms on broadleaf signalgrass often occurred independently. Symptomatic leaf tissues from 15 to 33 plants of each species and stem and root tissues from 4 to 14 plants of johnsongrass and yellow foxtail were surface disinfested, plated on water agar, and examined for sporulation after 5 to 10 days (2,3). Pathogens were identified by specific morphological features of spores and sporulation as on bermudagrass (3), and axenic cultures were established by spore transfers to cornmeal agar. Bipolaris cynodontis (Marig.) Shoemaker, Curvularia lunata (Wakk.) Boedijn, C. geniculata (Tracy & Earle) Boedijn, and Exserohilum rostratum (Drechs.) Leonard & Suggs were isolated from symptomatic leaves of all three grasses and frequently also observed on stems and roots. B. stenospila (Drechs.) Shoemaker was observed only on broadleaf signalgrass (19 of 33 plants) and B. spicifera (Banier) Subr. on johnsongrass and yellow foxtail. Species most frequent on leaves (58 to 100%) were B. spicifera, C. lunata, and E. rostratum on johnsongrass and yellow foxtail and B. cynodontis, B. stenospila, and E. rostratum on broadleaf signalgrass. The three grasses were grown from seed in potting mix in the greenhouse (one plant per 375-cm3 container), and five replicates 31 to 60 days old were inoculated with a mixture of three isolates of each pathogen observed on them in two experiments. Conidia produced from infested wheat and oat grain were atomized onto foliage (1.2 to 4 × 104 conidia per ml, 20 ml per plant) as described (2). All pathogens incited similar necrotic lesions and streaks on the three grasses after 12 to 15 days, and B. stenospila also caused extensive golden yellow chlorosis on broadleaf signalgrass. All pathogens caused significant (P = 0.05) necrosis (means = 5 to 35% of foliage necrotic based on visual estimates, controls = 1 to 3%), and all were reisolated and grown in pure culture by spore transfers to cornmeal agar from surface-disinfested, symptomatic leaf tissue of each grass. When bermudagrass grown from seed was inoculated at similar spore concentrations, isolates of E. rostratum, B. cynodontis, and B. spicifera from two or all three grasses caused symptoms as severe as did isolates from bermudagrass. Results document new North American or worldwide records of occurrence and pathogenicity for B. cynodontis, C. geniculata, and C. lunata on all three grasses, B. stenospila and E. rostratum on broadleaf signalgrass, and B. spicifera on johnsongrass and yellow foxtail (1). These volunteer grasses, bermudagrass, and the six fungi all appear to represent large, interacting complexes of multiple hosts and potentially cross-infecting pathogens. Reference: (1) D. Farr et al. Fungal Databases. Systematic Botany and Mycology Laboratory. Online publication. USDA, ARS, 2005. (2) R. Pratt, Agron. J. 92:512, 2000. (3) R. Pratt. Phytopathology 95:1183, 2005.
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McGregor, John T., Roy J. Smith y Ronald E. Talbert. "Broadleaf Signalgrass (Brachiaria platyphylla) Duration of Interference in Rice (Oryza sativa)". Weed Science 36, n.º 6 (noviembre de 1988): 747–50. http://dx.doi.org/10.1017/s0043174500075767.
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Interference from broadleaf signalgrass at a density of 180 plants/m2reduced rough rice yields of ‘Bond’ a maximum of 48% at 95 days after rice emergence and reduced yields of ‘Mars' a maximum of 21% from season-long interference. Interference durations of 40 days or longer reduced the panicles/m2, culms/m2, and plant height of rice. Straw dry weight of Bond and Mars was reduced 41 and 26%, respectively, from season-long interference. Increased durations of weed interference did not affect the number of spikelets/panicle, percent filled spikelets, rough kernel weight, or head rice yield of either cultivar. Broadleaf signalgrass produced less dry weight and fewer panicles/m2when grown with Mars than with Bond.
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Johnson, W. Carroll y Harold D. Coble. "Effects of Three Weed Residues on Weed and Crop Growth". Weed Science 34, n.º 3 (mayo de 1986): 403–8. http://dx.doi.org/10.1017/s0043174500067072.
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Broadleaf signalgrass [Brachiaria platyphylla(Griseb.) Nash # BRAPP has recently become the dominant annual grass in certain fields of the North Carolina Coastal Plains. Previously, fall panicum (Panicum dichotomiflorumMichx. # PANDI) and large crabgrass [Digitaria sanguinalis(L.) Scop. # DIGSA] were the dominant annual grasses in the region. One of the possible reasons for the observed population shift could be production of inhibitors or stimulators by one species that affects the population dynamics of the other species. Studies were initiated to evaluate the effects of broadleaf signalgrass, large crabgrass, and fall panicum residue, applied as a mulch or soil incorporated, on five indicator species: the three weeds themselves, corn (Zea maysL.), and soybean [Glycine max(L.) Merr.]. At expected residue levels, the degree of inhibition or stimulation from fall panicum and broadleaf signalgrass was determined to be significant for some indicator species. When such responses were seen, the amount of residue necessary to produce these results was usually within the concentrations normally observed in field situations. Based on these results, it appears that the observed population shift is partially mediated by the production of inhibitors or stimulators through plant residue. Other factors such as differential herbicide selectivity and crop rotation are being investigated.
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Rankins, Alfred, John D. Byrd, Donald B. Mask, Jimmy W. Barnett y Patrick D. Gerard. "Survey of Soybean Weeds in Mississippi". Weed Technology 19, n.º 2 (junio de 2005): 492–98. http://dx.doi.org/10.1614/wt-04-197r2.
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A survey was conducted in 2000 across 38 counties in Mississippi on 192 randomly selected soybean fields to assess the most common occurring weeds. Statewide, prickly sida, which was present in 40% of the fields sampled, was the most common. Pitted and entireleaf morningglory were present in 34 and 29% of the soybean fields, respectively. Broadleaf signalgrass and barnyardgrass were the most common annual grasses, and yellow nutsedge was the most common sedge observed. Trumpetcreeper and redvine were the most common perennial vines. In the Mississippi Delta region of Mississippi, prickly sida was present in 45% of the fields sampled. The trend of occurrence of other species in the Delta mirrored statewide results. In eastern Mississippi, prickly sida and broadleaf signalgrass were found in 43% of soybean fields. Sicklepod, common cocklebur, and balloonvine were more prevalent in eastern Mississippi, when compared with the Mississippi Delta. Since 1982, there has been a sevenfold decline in the occurrence of common cocklebur and a fourfold decline in the occurrence of johnsongrass in Mississippi soybean. Also, the occurrences of redroot pigweed, common ragweed, and fall panicum have declined. Conversely, the occurrences of yellow nutsedge and broadleaf signalgrass have increased. The occurrences of barnyardgrass, prickly sida, redvine and trumpetcreeper have been relatively static over the past two decades.
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Teixeira, Renato Alves, Tatiana Gazel Soares, Antonio Rodrigues Fernandes y Anderson Martins de Souza Braz. "Grasses and legumes as cover crop in no-tillage system in northeastern Pará Brazil". Acta Amazonica 44, n.º 4 (diciembre de 2014): 411–18. http://dx.doi.org/10.1590/1809-4392201305364.
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Studies to select one or more species of coverage plants adapted to Amazonian soil and climate conditions of the Amazon are a promising strategy for the improvement of environmental quality, establishing no-till agricultural systems, and thereby reducing the impacts of monoculture farming. The aim of this study was to assess the persistence time, half-life time, macronutrient content and accumulation, and C:N ratio of straw coverage in a Ultisol in northeastern Pará. Experimental design was randomized blocks with five treatments and five replicates. Plants were harvested after 105 days, growth and biomass production was quantified. After 84 days, soil coverage was 97, 85, 52, 50, and 15% for signalgrass (Brachiaria brizantha) (syn. Urochloa), dense crowngrass (Panicum purpurascens), jack bean (Canavalia ensiformes), pearl millet (Pennisetum americanum) and sunn hemp (Crotalaria juncea,), respectively. Signalgrass yielded the greatest dry matter production (9,696 kg ha-1). It also had high C:N ratio (38.4), long half-life (86.5 days) and a high persistence in the field. Jack bean also showed high dry matter production (8,950 kg ha-1), but it had low C:N ratio (17.4) and lower half-life time (39 days) than the grasses. These attributes indicate that signalgrass and jack bean have a high potential for use as cover plants in no-till agricultural systems in the State of Pará.
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FREITAS, M. A. M., D. V. VALADÃO SILVA, M. F. SOUZA, A. A. SILVA, D. T. SARAIVA, M. M. FREITAS, P. R. CECON y L. R. FERREIRA. "Levels of nutrients and grain yield of maize intercropped with signalgrass (Brachiaria) in different arrangements of plants". Planta Daninha 33, n.º 1 (marzo de 2015): 49–56. http://dx.doi.org/10.1590/s0100-83582015000100006.
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Competition between maize and signalgrass can economically cripple the intercropping by the reduced yield of maize and dry matter content of the forage. In seeking to define plant arrangements which make this system more efficient, this research was held with the objective of assessing the effects of interference of densities of signalgrass (Urochloa Brizantha) on nutrition and on maize grain yield. Two field experiments were conducted in a randomized block design with four replications. Treatments were arranged similarly in both experiments, in a 2 x 4 factorial design, the first factor being the dose of Nicosulfuron herbicide applied (0 and 8 g ha-1) and the second factor being the forage seeding rates (0, 2, 4 and 6 kg of seeds per hectare). The interference of signalgrass reduced foliar nitrogen, potassium and phosphorus content in maize plants intercropped with the forage. Higher values of grain yield were observed with the reduction of the spacing and the application of the recommended herbicide underdose (8 g ha-1). It was concluded that, regardless of the seeding density of U. Brizantha, reducing the maize seeding inter-rows spacing, combined with the application of an underdose of Nicosulfuron, caused a positive effect by reducing the initial forage growth, resulting in less interference of Urochloa brizantha on nutrient uptake by the maize plants and grain yield of the crop.
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Scott, Robert C., David R. Shaw, William B. O'neal y Troy D. Klingaman. "Spray Adjuvant, Formulation, and Environmental Effects on Synergism from Post-Applied Tank Mixtures of SAN 582H with Fluazifop-P, Imazethapyr, and Sethoxydim". Weed Technology 12, n.º 3 (septiembre de 1998): 463–69. http://dx.doi.org/10.1017/s0890037x00044158.
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The effect of adding a spray adjuvant to SAN 582H tank mixtures with fluazifop-P, imazethapyr, and sethoxydim was evaluated. SAN 582H synergistically increased broadleaf signalgrass control with reduced rates of all three postemergence (POST) herbicides when no spray adjuvant was used and when crop oil concentrate was added. For example, broadleaf signalgrass control increased from 50% to 83% when SAN 582H was tank-mixed with 52 g ai/ha sethoxydim and crop oil concentrate. In another experiment, several formulations of SAN 582H, including blank solvent-only formulations (no SAN 582H), were evaluated in combination with a reduced rate of sethoxydim to determine the source of synergism from tank mixtures. The SAN 582H molecule, not the carrier solvents in formulated product, was determined to be the source of synergism. The synergistic properties of SAN 582H were compared to other chloroacetamides. Synergism from acetochlor was similar to SAN 582H when applied POST with a reduced rate of either fluazifop-P, imazethapyr, or sethoxydim for grass control. Metolachlor also synergistically increased the control of grasses with the POST herbicides; however, metolachlor caused considerable phytotoxicity when applied alone and synergistic interactions were detected less frequently. The efficacy of sethoxydim mixed with SAN 582H was evaluated under different soil moisture conditions. Broadleaf signalgrass control increased from 81% to 93% under dry, moisture-stressed conditions when 210 g/ha sethoxydim was tank- mixed with SAN 582H.
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O'Barr, John H., Garry N. McCauley, Rodney W. Bovey, Scott A. Senseman y James M. Chandler. "Rice Response to Clomazone as Influenced by Application Rate, Soil Type, and Planting Date". Weed Technology 21, n.º 1 (marzo de 2007): 199–205. http://dx.doi.org/10.1614/wt-05-044.1.
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Clomazone is an effective herbicide widely used for PRE grass control in rice. However, use of clomazone on sandy textured soils of the western Texas rice belt can cause serious rice injury. Two field experiments at three locations were conducted in 2002 and 2003 to determine the optimum rate range that maximizes barnyardgrass and broadleaf signalgrass control and minimizes rice injury across a wide variety of soil textures and planting dates. At Beaumont (silty clay loam), Eagle Lake (fine sandy loam), and Ganado (fine sandy loam), TX, PRE application of 0.34 kg ai/ha clomazone applied to rice planted in March, April, or May optimized barnyardgrass and broadleaf signalgrass control and rice yield while minimizing rice injury. Data suggest that, although injury might occur, clomazone is safe to use in rice on sandy textured soils.
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Teuton, Travis C., Barry J. Brecke, J. Bryan Unruh, Greg E. MacDonald, Grady L. Miller y Joyce Tredaway Ducar. "Factors affecting seed germination of tropical signalgrass (Urochloa subquadripara)". Weed Science 52, n.º 3 (mayo de 2004): 376–81. http://dx.doi.org/10.1614/ws-03-121r1.
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Ezenwa, Ike V., Robert S. Kalmbacher, John D. Arthington y Findlay M. Pate. "Creeping Signalgrass Versus Bahiagrass for Cow and Calf Grazing". Agronomy Journal 98, n.º 6 (noviembre de 2006): 1582–88. http://dx.doi.org/10.2134/agronj2006.0097.
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Smith, Roy J. "Weed Thresholds in Southern U.S. Rice,Oryza sativa". Weed Technology 2, n.º 3 (julio de 1988): 232–41. http://dx.doi.org/10.1017/s0890037x00030505.
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Knowledge of interference thresholds, biology, and growth habits of weeds of rice is essential to implement timely, effective, economical weed control technology for profitable rice production. Regression analyses were used to determine threshold levels for weed densities and durations of interference for major weeds of rice. Weed threshold information for individual species or combinations of species can be used to develop models for initiating control inputs and determining their costs and returns. Among the grass weeds in density experiments, red rice reduced rice grain yields the most followed by barnyardgrass, beared sprangletop, and broadleaf signalgrass. Among broadleaf/aquatic weeds in density experiments, hemp sesbania reduced rice grain yields the most followed by northern jointvetch, ducksalad, spreading dayflower, and eclipta. Barnyardgrass, broadleaf signalgrass, and ducksalad interfered with rice the most during early season, whereas eclipta, hemp sesbania, northern jointvetch, red rice, and spreading dayflower caused greater interference during mid- to late-season.
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Palmer, Eric W., David R. Shaw y James C. Holloway. "Influence of CGA-277476 on Efficacy of Postemergence Graminicides". Weed Technology 13, n.º 1 (marzo de 1999): 48–53. http://dx.doi.org/10.1017/s0890037x00044894.
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Field experiments were conducted at three Mississippi locations to evaluate potential antagonism when postemergence graminicides were tank-mixed with CGA-277476 and to determine if the antagonism could be overcome with an increase in graminicide rate. At all locations when the 1X rate of clethodim, fluazifop-P, or quizalofop was tank-mixed with 79 g ai/ ha CGA-277476, johnsongrass, broadleaf signalgrass, and barnyardgrass control was reduced 5 to 30%. When the graminicide rates were increased to 1.5X, antagonism was still present for fluazifop-P and quizalofop. However, 156 g ai/ha clethodim overcame the antagonism when tank-mixed with 79 g/ha CGA-277476 compared to 105 g/ha clethodim. CGA-277476 alone controlled barnyardgrass and broadleaf signalgrass 38 to 63% and johnsongrass 60 to 85%. There were no differences in soybean yields with graminicides applied alone or tank-mixed with CGA-277476.
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Pearson, Bree A., Robert C. Scott y V. Frank Carey. "Urea Ammonium Nitrate Effects on Bispyribac and Penoxsulam Efficacy". Weed Technology 22, n.º 4 (diciembre de 2008): 597–601. http://dx.doi.org/10.1614/wt-07-139.1.
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Experiments were conducted at the Lonoke Extension and Applied Research Center greenhouse at Lonoke, AR, to evaluate the effects of urea ammonium nitrate (UAN) on bispyribac and penoxsulam efficacy on barnyardgrass, hemp sesbania, and broadleaf signalgrass. Herbicide treatments included bispyribac at 17.9 or 35.8 g ai/ha or penoxsulam at 24.4 or 48.9 g ai/ha tank mixed with (1) no adjuvant, (2) a nonionic organosilicone (OSL) adjuvant at 0.125% v/v, (3) a methylated seed oil/organosilicone (MSO/OSL) adjuvant at 0.37 L/ha, (4) a proprietary blend of MSO/OSL/UAN at 2% v/v, (5) UAN at 2% v/v, (6) OSL at 0.125% plus UAN at 2% v/v, or (7) MSO/OSL at 0.37 L/ha plus UAN at 2% v/v. In addition to these adjuvants, penoxsulam was also applied with crop oil concentrate (COC) at 2.34 L/ha and with COC at 2.34 L/ha plus UAN at 2% v/v. The addition of UAN to either herbicide plus an adjuvant increased herbicide efficacy on barnyardgrass in the greenhouse, with 95 to 99% biomass reduction of three- to four-leaf barnyardgrass and 88 to 92% biomass reduction of one- to three-tiller barnyardgrass. UAN did not generally increase efficacy on hemp sesbania, as control was 90% or higher with treatments containing either herbicide and a recommended adjuvant. Adding UAN did not increase efficacy on broadleaf signalgrass. Broadleaf signalgrass control was highly variable and no treatment provided more than 65% biomass reduction.
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Burke, Ian C., Walter E. Thomas, Janet F. Spears y John W. Wilcut. "Influence of environmental factors on broadleaf signalgrass (Brachiaria platyphylla) germination". Weed Science 51, n.º 5 (septiembre de 2003): 683–89. http://dx.doi.org/10.1614/0043-1745(2003)051[0683:ioefob]2.0.co;2.
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Teuton, Travis C., Christopher L. Main, Thomas C. Mueller, John B. Wilkerson, Barry J. Brecke y J. Bryan Unruh. "Prediction Modeling for Tropical Signalgrass (Urochloa subquadripara ) Emergence in Florida". Applied Turfgrass Science 2, n.º 1 (2005): 1–3. http://dx.doi.org/10.1094/ats-2005-0425-01-br.
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Carbonell, M. V., E. Martínez, J. E. Díaz, J. M. Amaya y M. Flórez. "Influence of magnetically treated water on germination of signalgrass seeds". Seed Science and Technology 32, n.º 2 (1 de julio de 2004): 617–19. http://dx.doi.org/10.15258/sst.2004.32.2.30.
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Cross, Robert B., Lambert B. McCarty y Alan G. Estes. "Postemergence Tropical Signalgrass (Urochloa subquadripara) Control with Nonorganic Arsenical Herbicides". Weed Technology 30, n.º 3 (septiembre de 2016): 815–21. http://dx.doi.org/10.1614/wt-d-16-00012.1.
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Tropical signalgrass (TSG) has become a serious weed problem in tropical and subtropical regions such as Florida in recent years in association with the ban of organic arsenical herbicide use in turf. The purpose of this research was to identify alternative POST herbicides that control TSG. Two field experiments were conducted in bermudagrass golf course fairways in south and central Florida in 2014 and 2015. Several nonorganic arsenical herbicide treatments controlled TSG. In the first experiment, treatments containing amicarbazone alone and in combination with other herbicides provided > 97% TSG control 12 wk after initial treatment (WAIT) in 2014 and 2015. These included a single application of amicarbazone at 0.49 kg ai ha−1, or sequential applications of amicarbazone at 0.25 kg ha−1in combination with foramsulfuron at 0.04 kg ai ha−1, sulfentrazone + imazethapyr at 0.25 kg ai ha−1, thiencarbazone + foramsulfuron + halosulfuron at 0.14 kg ai ha−1, and thiencarbazone + iodosulfuron + dicamba at 0.18 kg ai/ae ha−1. In the second experiment, sequential applications of thiencarbazone + foramsulfuron + halosulfuron at 0.14 kg ha−1in combination with either quinclorac at 0.84 kg ai ha−1or metribuzin at 0.28 kg ai ha−1provided ≥ 85% TSG control 12 WAIT in both years.
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Scott, Robert, David R. Shaw y William L. Barrentine. "Glyphosate Tank Mixtures with SAN 582 for Burndown or Postemergence Applications in Glyphosate-Tolerant Soybean (Glycine max)". Weed Technology 12, n.º 1 (marzo de 1998): 23–26. http://dx.doi.org/10.1017/s0890037x00042512.
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Field experiments were conducted to evaluate postemergence (POST)-applied tank mixtures of 560, 1,120, and 1,680 g ai/ha glyphosate with or without 1,120 g ai/ha SAN 582 (proposed name, dimethenamid) as burndown treatments or POST in glyphosate-tolerant soybean. SAN 582 was not antagonistic with glyphosate at the glyphosate rates evaluated. In the burndown study, glyphosate controlled horseweed 98% or more and curly dock 82% or more with or without SAN 582. However, broadleaf signalgrass emerged after the burndown treatments were applied. All tank mixtures that included SAN 582 controlled broadleaf signalgrass 84 to 96%, 6 wk after treatment. In the glyphosate-tolerant soybean study, glyphosate controlled barnyardgrass and johnsongrass present at the time of application 89% or more, regardless of rate. Tank mixtures of SAN 582 with glyphosate controlled late-season flushes of barnyardgrass through residual activity of the SAN 582. Applying SAN 582 with glyphosate improved soybean yield 500 kg/ha over glyphosate applied alone.
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Eure, Peter M., David L. Jordan, Loren R. Fisher y Alan C. York. "Efficacy of Herbicides When Spray Solution Application Is Delayed". International Journal of Agronomy 2013 (2013): 1–7. http://dx.doi.org/10.1155/2013/782486.
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Information is limited concerning the impact of delaying applications of pesticides after solution preparation on efficacy. Experiments were conducted to determine weed control when diclosulam, dimethenamid-P, flumioxazin, fomesafen, imazethapyr, pendimethalin, andS-metolachlor were applied preemergence the day of solution preparation or 3, 6, and 9 days after solution preparation. Herbicide solutions were applied on the same day regardless of when prepared. Control of broadleaf signalgrass, common lambsquarters, entireleaf morningglory, and Palmer amaranth by these herbicides was not reduced regardless of when herbicide solutions were prepared. Surprisingly entireleaf morningglory control by all herbicides increased when herbicide application was delayed by 9 days. In separate experiments, control of broadleaf signalgrass by clethodim, common ragweed by glyphosate and lactofen, entireleaf morningglory by lactofen, Italian rye grass by glyphosate and paraquat, and Palmer amaranth by atrazine, dicamba, glufosinate, glyphosate, imazethapyr, lactofen, and 2,4-D was affected more by increase in weed size due to delayed application than the time between solution preparation and application.
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Lancaster, Zachary D., Jason K. Norsworthy y Robert C. Scott. "Evaluation of Quizalofop-Resistant Rice for Arkansas Rice Production Systems". International Journal of Agronomy 2018 (2018): 1–8. http://dx.doi.org/10.1155/2018/6315865.
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Due to the ongoing evolution of herbicide-resistant weeds, new technologies are needed to maintain effective levels of control. A new rice variety that will be resistant to quizalofop, an acetyl coenzyme A carboxylase- (ACCase-) inhibiting herbicide, is currently under development. With the anticipated launch of this technology in 2018, multiple experiments were conducted to determine effectiveness of the quizalofop-resistant rice system for common grass weed species found in Arkansas rice production. One hundred and twenty-six barnyardgrass populations were collected across Arkansas and treated with quizalofop at 80 g ai ha−1 to determine a baseline of response. All populations evaluated were effectively controlled (≥92%) by quizalofop, with only 13 populations resulting in lower than 98% control. A greenhouse and field trial were conducted to compare efficacy of quizalofop to currently labeled rice graminicides for control of common rice grass weeds. Results from the greenhouse experiment showed that quizalofop treatments resulted in greater efficacy of common grass weeds compared to cyhalofop or fenoxaprop. This was especially apparent at the larger grass growth stages. A field experiment conducted compared season-long weed control programs of quizalofop to fenoxaprop and cyhalofop. The quizalofop-containing treatments were no better than fenoxaprop and cyhalofop for barnyardgrass and broadleaf signalgrass control. Barnyardgrass and broadleaf signalgrass control were greater than 96% for all herbicide treatments. An additional field experiment was conducted to determine the best rate structure for sequential applications of quizalofop in rice. Sequential applications of quizalofop at 120 g ha−1 followed by 120 g ha−1 two weeks later resulted in the highest barnyardgrass and broadleaf signalgrass control. Likewise, applying the full seasonal use rate of 240 g ha−1 of quizalofop resulted in greater control compared to 200 and 160 g ha−1. Results from this research indicate a strong benefit from quizalofop use in rice.
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Buehring, Nathan W., Ronald E. Talbert y Ford L. Baldwin. "Rice (Oryza sativa) Response and Annual Grass Control with Graminicides". Weed Technology 20, n.º 3 (septiembre de 2006): 738–44. http://dx.doi.org/10.1614/wt-05-153r.1.
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Field studies were conducted to evaluate rice injury and control of propanil-resistant and -susceptible (natural infestation) barnyardgrass, broadleaf signalgrass, and Amazon sprangletop with BAS 625, cyhalofop, and fenoxaprop plus the safener isoxadifen in rice. BAS 625 at 100 g ai/ha applied to two- to three-leaf rice resulted in 19 to 72% injury in three of four experiments. Fenoxaprop plus isoxadifen at 90 + 98 g ai/ha injured rice 11 to 31%, and cyhalofop at 280 g ai/ha consistently resulted in minimal rice injury. The most effective control (84 to 99%) of propanil-resistant and propanil-susceptible barnyardgrass across all experiments was achieved with sequential applications of the BAS 625 at 75 and 100 g ai/ha, cyhalofop at 210 and 280 g ai/ha, and fenoxaprop plus isoxadifen at 68 + 74 and 90 + 98 g ai/ha. When the graminicides were applied to four- to six-leaf rice (one tiller), propanil-resistant and propanil-susceptible barnyardgrass control was generally very poor. Fenoxaprop plus isoxadifen controlled broadleaf signalgrass 91 to 100%, even when applied once to four- to six-leaf rice. BAS 625 at 75 and 100 g ai/ha and cyhalofop at 210 and 280 g ai/ha applied sequentially provided consistent broadleaf signalgrass control (≥98%). Amazon sprangletop control was good (85 to 99%) with fenoxaprop plus isoxadifen at 45 + 49, 68 + 74, and 90 + 98 g ai/ha (applied in a single application or sequentially), BAS 625 at 100 g ai/ha applied to two- to three-leaf and four- to six-leaf rice or 50, 75, and 100 g ai/ha applied sequentially, and cyhalofop at 140, 210, and 280 g ai/ha applied to two- to three-leaf rice or sequentially.
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Santos, Manoel Eduardo Rozalino, Dilermando Miranda da Fonseca, Virgílio Mesquita Gomes, Thiago Gomes dos Santos Braz, Simone Pedro da Silva, Ronan Lopes Albino, Andreza Luzia Santos y Guilherme Portes Silva. "Grazing patterns on signalgrass pasture according to location of cattle feces". Revista Brasileira de Zootecnia 41, n.º 4 (abril de 2012): 898–904. http://dx.doi.org/10.1590/s1516-35982012000400010.
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Shabana, Yasser M., Carol M. Stiles, R. Charudattan y Ayman H. Abou Tabl. "Evaluation of Bioherbicidal Control of Tropical Signalgrass, Crabgrass, Smutgrass, and Torpedograss". Weed Technology 24, n.º 2 (junio de 2010): 165–72. http://dx.doi.org/10.1614/wt-09-065.1.
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Tropical signalgrass (TSG) causes serious problems for sod production and turf maintenance in Florida. Other grasses such as large crabgrass (CG), smutgrass (SG), thin paspalum (TP), and torpedograss (TG) can be problematic as well. Several emulsion formulations composed of mycelium or mycelium-free culture filtrate (or both) of the fungal pathogen Drechslera gigantea (DG) and Sunspray 6E oil were tested with or without ammonium sulfate or pelargonic acid (n-nonanoic acid; a natural product registered as a biorational herbicide) in greenhouse and field trials. A 30% Sunspray 6E oil formulation containing DG mycelium (10 g), DG culture filtrate (70 ml), and 4.5 g of ammonium sulfate caused 88 to 100% injury on TSG, CG, SG, and TG in greenhouse trials. The injury resulted from disease as well as phytotoxicity of the culture filtrate, oil, and ammonium sulfate. An emulsion formulation composed of 30% Sunspray 6E oil and 70% DG culture filtrate amended with 2% (v/v) pelargonic acid killed SG 2 wk after application. DG formulations containing ammonium sulfate or pelargonic acid produced lower levels of injury when treated grasses were exposed to a 24-h dew period compared with those treated and not exposed to dew. Formulations containing DG mycelium, DG culture filtrate, and ammonium sulfate or pelargonic acid are effective and promising for control of weedy grasses. Further evaluations of these formulations under field conditions are justified.
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Mueller, Thomas C. y Lawrence E. Steckel. "Efficacy and Dissipation of Pyroxasulfone and Three Chloroacetamides in a Tennessee Field Soil". Weed Science 59, n.º 4 (diciembre de 2011): 574–79. http://dx.doi.org/10.1614/ws-d-11-00003.1.
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Field studies were conducted in Knoxville, TN, over a 2-yr period (2007 and 2008) to determine the field dissipation rate and efficacy of pyroxasulfone, acetochlor, dimethenamid, ands-metolachlor to broadleaf signalgrass. Depending on rainfall patterns, pyroxasulfone at 209 g ai ha−1provided broadleaf signalgrass control of > 75%, which was equal to or superior to acetochlor at 1,740 g ai ha−1, dimethenamid at 1,500 g ai ha−1ands-metolachlor at 1,420 g ai ha−1. Pyroxasulfone provided residual control into the growing season and provides a tool for resistance management of later-emerging weeds. Herbicide dissipation was rapid in all soils (half-life usually < 20 d), although it was slower in a dry year. The order of herbicide dissipation and half-life in days in the 2 yr was acetochlor (3.5, 5 d) > dimethenamid (5, 9 d) >s-metolachlor (8.8, 27 d) > pyroxasulfone (8.2, > 71 d). There was poor correlation between observed weed control at 45 d after treatment and chemically determined herbicide concentrations at that same time, with ∼ 40% difference in 2007 and ∼ 50% difference in 2008.
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Jordan, David L., P. Roy Vidrine, James L. Griffin y Daniel B. Reynolds. "Influence of Adjuvants on Efficacy of Clethodim". Weed Technology 10, n.º 4 (diciembre de 1996): 738–43. http://dx.doi.org/10.1017/s0890037x00040744.
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Field experiments evaluated barnyardgrass, broadleaf signalgrass, and rhizomatous johnsongrass control with clethodim applied with Agri-Dex® crop oil concentrate at 1.0% v/v, the adjuvant Dash® at 1.0% v/v, the methylated seed oil Sun-It II® at 1.0% v/v, a blend of silicone surfactant plus methylated seed oil (Dyne-Amic® at 0.5% v/v) or nonionic surfactant (Kinetic® HV at 0.125% v/v), two silicone surfactants (Sylgard® 309 and Silwet L-77® surfactant) at 0.125% v/v, two other conventional nonionic surfactants (Latron AG-98™ and Induce®) at 0.25% v/v, and the acidified soya phospholipid LI-700®. When compared with the conventional nonionic or silicone-based surfactants and LI-700, clethodim at 70 g ai/ha controlled barnyardgrass more effectively when applied with Dash or Sun-It II. Broadleaf signalgrass and rhizomatous johnsongrass were controlled more effectively when clethodim was applied with Agri-Dex, Dash, Sun-It II, or Dyne-Amic. Clethodim at 70 g/ha applied with Dash or Sun-It II controlled grasses equally or greater than clethodim at 140 g/ha.
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Grichar, W. James. "Using Soil-Applied Herbicides in Glyphosate-Resistant Soybeans along the Texas Gulf Coast". Weed Technology 20, n.º 3 (septiembre de 2006): 633–39. http://dx.doi.org/10.1614/wt-05-049r1.1.
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Field studies were conducted at four locations over a 2-year period to evaluate the utility of soil-applied herbicides and glyphosate timing for weed control and soybean yield. Pendimethalin,S-metolachlor plus metribuzin, and flufenacet plus metribuzin were applied pre-emergence (PRE) alone or followed by glyphosate applied early postemergence (EPOST), late postemergence (LPOST), or EPOST plus LPOST. Soil-applied herbicides or glyphosate alone failed to control (<45%) broadleaf signalgrass in 2003 due to late-season rainfall, which accounted for a late flush of growth. In 2004, soil-applied herbicides alone controlled 79–100% broadleaf signalgrass, whereas glyphosate alone or in combination with soil-applied herbicides controlled at least 99%. Barnyardgrass and tall waterhemp were controlled at least 87% with soil-applied herbicides alone and at least 95% when glyphosate was used alone or in combination with a soil-applied herbicide. Soybean yield varied, but at only one location did herbicide treatments produce higher yields than the untreated check. Under low to moderate weed pressure, the use of a soil-applied herbicide followed by glyphosate failed to increase net returns over soil-applied herbicides alone.
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Parker, William B., L. Thompson y F. Michael Godley. "Integrating Sethoxydim into Soybean (Glycine max) Weed Management Systems". Weed Science 33, n.º 1 (enero de 1985): 100–108. http://dx.doi.org/10.1017/s0043174500084009.
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On-farm field experiments were conducted in the Piedmont Plateau and Coastal Plain of North Carolina in 1981 and 1982 to investigate the integration of sethoxydim {2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one} with other chemical and cultural weed control tactics into soybean [Glycine max(L.) Merr.] weed management systems. Sethoxydim at 0.2 kg ai/ha provided control of broadleaf signalgrass [Brachiaria platyphylla(Griseb.) Nash. # BRAPP], large crabgrass [Digitaria sanguinalis(L.) Scop. # DIGSA], and fall panicum [Panicum dichotomiflorumMichx. # PANDI) equal to control achieved with registered rates of the soil-applied herbicides alachlor [2-chloro-2’,6’-diethyl-N-(methoxymethyl)acetanilide] and trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine). Control of broadleaf weed species with the postemergence herbicides bentazon [3-isopropyl-1H-2,1,3-benzothiadiazin-4-(3H)-one 2,2-dioxide] and acifluorfen {5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid} equaled or exceeded the control obtained with the soil-applied herbicides linuron [3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea] and metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazin-5-(4H)-one]. Applications of 0.22 kg/ha of sethoxydim 2, 3, 4, and 5 weeks after soybean planting provided season-long control of fall panicum and crabgrass in 1981. In 1982, crabgrass control was 88 to 99% up to 4 weeks after planting. Later applications provided inadequate control of the grass species. Variations in volume and pressure of application had no effect on control of 10-cm goosegrass [Eleusine indica(L.) Gaertn. # ELEIN] or broadleaf signalgrass with 0.2 kg/ha of sethoxydim. Increasing pressure increased control of 30-cm goosegrass and broadleaf signalgrass. Increasing volume increased only control of goosegrass. Bentazon and acifluorfen provided better control of broadleaf weeds when applied early than when applied late. In two of four experiments tank mixtures of sethoxydim and bentazon resulted in an initial decrease in grass control compared to corresponding sequential applications. Soybean yields were comparable, however.