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Martin A. Locke - One of the best experts on this subject based on the ideXlab platform.
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ORIGINAL PAPER
2015Co-Authors: Robert M Zablotowicz, Martin A. Locke, Lewis A. GastonAbstract:Tillage and cover effects on soil microbial properties and Fluometuron degradatio
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Fluometuron Interactions in Crop Residue-Managed Soils
2015Co-Authors: Martin A. Locke, Robert M Zablotowicz, Lewis A. GastonAbstract:This paper reviews a series of studies concerning Fluometuron (N,N-dimethyl-N'-[3-(trifluoromethyl)-phenyl]urea) interac tions in soil and herbicide-desiccated crop residues. The objective of these studies was to evaluate effects of tillage and cover crop management on Fluometuron sorption and degradation. Length of equilibration time and organic C level appeared to be the dominant factors influencing Fluometuron sorption quantity and kinetics. Related to these factors, resident time and plant surface accumulation of organic residues may influence the potential for subsequent movement in soil. Fall-seeded ryegrass (Lolium multiforum) cover in a cotton (Gossypium hirsutum L.) cropping system enhanced biological soil quality and the poten tial for Fluometuron degradation. Fluometuron was more rapidly degraded in annual ryegrass residues and conventional tillage (CT) or no-tillage (NT) soils under a fall-seeded annual ryegrass cover crop than in soils without residue
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constructed wetlands as a component of the agricultural landscape mitigation of herbicides in simulated runoff from upland drainage areas
Chemosphere, 2011Co-Authors: Martin A. Locke, Robert M Zablotowicz, Charles T Bryson, Mark A. Weaver, R W Steinriede, R F CullumAbstract:Constructed wetlands are a recommended practice for buffering pollutant source areas and receiving waters. A wetland consisting of a sediment trap and two treatment cells was constructed in a Mississippi Delta lake watershed. A 3-h simulated runoff event was initiated (2003) to evaluate fate and transport of atrazine and Fluometuron through the wetland. Water samples were collected during a runoff simulation and then afterward at selected intervals for 21 d, and analyzed for the herbicides. Breakthrough patterns for herbicide concentrations in water samples during the first 20 h after simulated runoff showed peak concentrations in the first 6 h, with gradual tailing as the herbicide pulse was diluted in the second, excavated (deeper) cell. Atrazine and Fluometuron concentrations in the first (shallower, non-excavated) cell averaged 12- and 20-fold greater, respectively, than those in the second cell following simulated runoff, indicating entrapment in the first cell. Atrazine and Fluometuron concentrations in the shallower cell decreased 32% and 22%, respectively, 9 d following simulated runoff, indicating either degradation or sorption to soil or wetland flora. In the excavated cell, concentrations were even lower, and atrazine declined more rapidly than Fluometuron. Results indicate constructed wetlands can improve downstream water quality though sequestration or processing of pollutants.
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Influence of watershed system management on herbicide concentrations in Mississippi Delta oxbow lakes.
Science of The Total Environment, 2006Co-Authors: Robert M Zablotowicz, Martin A. Locke, L. Jason Krutz, Robert N. Lerch, Richard E. Lizotte, Scott S. Knight, R. Earl Gordon, R. Wade SteinriedeAbstract:The Mississippi Delta Management Systems Evaluation Area (MD-MSEA) project was established in 1994 in three small watersheds (202 to 1497 ha) that drain into oxbow lakes (Beasley, Deep Hollow, and Thighman). The primary research objective was to assess the implications of management practices on water quality. Monthly monitoring of herbicide concentrations in lake water was conducted from 2000 to 2003. Water samples were analyzed for atrazine, cyanazine, Fluometuron, metolachlor, and atrazine metabolites. Herbicide concentrations observed in the lake water reflected cropping systems of the watershed, e.g., atrazine and metolachlor concentrations were associated with the level of corn and sorghum production, whereas cyanazine and Fluometuron was associated with the level of glyphosate-sensitive cotton production. The dynamics of herbicide appearance and dissipation in lake samples were strongly influenced by herbicide use, lake hydrology, rainfall pattern, and land management practices. The highest maximum concentrations of atrazine (7.1 to 23.4 μ gL �1 ) and metolachlor (0.7 to 14.9 μ gL �1 ) were observed in Thighman Lake where significant quantities of corn were grown. Introduction of s-metolachlor and use of glyphosateresistant cotton coincided with reduced concentration of metolachlor in lake water. Cyanazine was observed in two lakes with the highest levels (1.6 to 5.5 μ gL �1 ) in 2000 and lower concentrations in 2001 and 2002 (b0.4 μ gL �1 ). Reduced concentrations of Fluometuron in Beasley Lake were associated with greater use of glyphosate-resistant cotton and correspondingly less need for soilapplied Fluometuron herbicide. In contrast, increased levels of Fluometuron were observed in lake water after Deep Hollow was converted from conservation tillage to conventional tillage, presumably due to greater runoff associated with conventional tillage. These studies indicate that herbicide concentrations observed in these three watersheds were related to crop and soil management practices.
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Laboratory assessment of atrazine and Fluometuron degradation in soils from a constructed wetland.
Chemosphere, 2004Co-Authors: Mark A. Weaver, Robert M Zablotowicz, Martin A. LockeAbstract:Constructed wetlands offer promise for removal of nonpoint source contaminants such as herbicides from agricultural runoff. Laboratory studies assessed the potential of soils to degrade and sorb atrazine and Fluometuron within a recently constructed wetland. The surface 3 cm of soil was sampled from two cells of a Mississippi Delta constructed wetland; one shallow area disturbed only hydrologically, and the second excavated to provide greater water-holding capacity. The excavated area was more acidic on average (pH 4.85 versus 5.21), but otherwise the physical properties and general microbial enzyme activities in the two areas were similar. Soils were treated with 84 and 68l gk g � 1 soil 14 C-ring labeled atrazine and Fluometuron, respectively, and incubated under either saturated (88% moisture, w:w) or flooded (1 cm standing water) conditions. Soils were sampled over 32 days and extracted for herbicide and metabolite analysis. Under saturated conditions, Fluometuron metabolized to desmethylFluometuron (DMF) with a half-life equal 25–27 days. However, under flooded conditions, the half-life of Fluometuron was more than 175 days. Atrazine dissipated rapidly in saturated and flooded soil with a half-life of approximately 23 days, but only 10% of atrazine was mineralized to CO2. The overall atrazine and Fluometuron dissipation rates were similar between the two cells, but each area had a different pattern of metabolite accumulation. The major route of atrazine dissipation was incorporation of atrazine residues into methanol-nonextractable (soil-bound) components, with minimal extractable metabolite accumulation. A mixed-mode extractant (potassium phosphate:acetonitrile) recovered greater amounts of 14 C-residues from atrazine-treated soils, suggesting that hydrolysis of atrazine to
Craig W Bednarz - One of the best experts on this subject based on the ideXlab platform.
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combined effects of constant versus variable intensity simulated rainfall and reduced tillage management on cotton preemergence herbicide runoff
Journal of Environmental Quality, 2006Co-Authors: Thomas L Potter, Clint C Truman, Timothy C Strickland, D D Bosch, Theodore M Webster, Dorcas H Franklin, Craig W BednarzAbstract:Pesticide runoff research relies heavily on rainfall simulation experiments. Most are conducted at a constant intensity, i.e., at a fixed rainfall rate; however, large differences in natural rainfall intensity is common. To assess implications we quantified runoff of two herbicides, Fluometuron and pendimethalin, and applied preemergence after planting cotton on Tifton loamy sand. Rainfall at constant and variable intensity patterns representative of late spring thunderstorms in the Atlantic Coastal Plain region of Georgia (USA) were simulated on 6-m 2 plots under strip- (ST) and conventional-tillage (CT) management. The variable pattern produced significantly higher runoff rates of both compounds from CT but not ST plots. However, on an event-basis, runoff totals (% applied) were not significantly different, with one exception: Fluometuron runoff from CT plots. There was about 25% more Fluometuron runoff with the variable versus the constant intensity pattern (P 5 0.10). Study results suggest that conduct of simulations using variable intensity storm patterns may provide more representative rainfall simulation-based estimates of pesticide runoff and that the greatest impacts will be observed with CT. The study also found significantly more Fluometuron in runoff from ST than CT plots. Further work is needed to determine whether this behavior may be generalized to other active ingredients with similar properties [low Koc (organic carbon partition coefficient) |100 mL g 21 ; high water solubility |100 mg L 21 ]. If so, it should be considered when making tillage-specific herbicide recommendations to reduce runoff potential.
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Fluometuron and pendimethalin runoff from strip and conventionally tilled cotton in the southern atlantic coastal plain
Journal of Environmental Quality, 2004Co-Authors: Thomas L Potter, Clint C Truman, D D Bosch, Craig W BednarzAbstract:In the Atlantic Coastal Plain region of southern Georgia (USA), cotton (Gossypium hirsutum L.) acreage increased threefold in the past decade. To more effectively protect water quality in the region, best management practices are needed that reduce pesticide runoff from fields in cotton production. This study compared runoff of two herbicides, Fluometuron [N,N-dimethyl-N'-[3-(trifluoromethyl)-phenyl]-urea] and pendimethalin [N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitro-benzenamine], from plots in strip-tillage (ST) and conventional-tillage (CT) management near Tifton, GA. Rainfall simulations were conducted one day after preemergence herbicide applications to 0.0006-ha plots and runoff from 0.15-ha plots due to natural rainfall following preemergence pendimethalin and Fluometuron and postemergence Fluometuron use was monitored. Pendimethalin runoff was greater under CT than ST due to strong pendimethalin soil sorption and higher erosion and runoff under CT. The highest losses, 1.3% of applied in CT and 0.22% of applied in ST, were observed during rainfall simulations conducted 1 DAT. Fluometuron runoff from natural rainfall was substantially lower from ST than from CT plots but the trend was reversed in rainfall simulations. In all studies, Fluometuron runoff was also relatively low (<1% of applied), and on plots under natural rainfall, desmethylFluometuron (DMF) represented about 50% of total Fluometuron runoff. Fluometuron's relatively low runoff rate appeared linked to its rapid leaching, and high DMF detection rates in runoff support DMF inclusion in Fluometuron risk assessments. Results showed that ST has the potential to reduce runoff of both herbicides, but Fluometuron leaching may be a ground water quality concern.
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Fluometuron and pendimethalin runoff from strip and conventionally tilled cotton in the southern atlantic coastal plain.
Journal of environmental quality, 2004Co-Authors: Thomas L Potter, Clint C Truman, D D Bosch, Craig W BednarzAbstract:In the Atlantic Coastal Plain region of southern Georgia (USA), cotton (Gossypium hirsutum L.) acreage increased threefold in the past decade. To more effectively protect water quality in the region, best management practices are needed that reduce pesticide runoff from fields in cotton production. This study compared runoff of two herbicides, Fluometuron [N,N-dimethyl-N'-[3-(trifluoromethyl)-phenyl]-urea] and pendimethalin [N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitro-benzenamine], from plots in strip-tillage (ST) and conventional-tillage (CT) management near Tifton, GA. Rainfall simulations were conducted one day after preemergence herbicide applications to 0.0006-ha plots and runoff from 0.15-ha plots due to natural rainfall following preemergence pendimethalin and Fluometuron and postemergence Fluometuron use was monitored. Pendimethalin runoff was greater under CT than ST due to strong pendimethalin soil sorption and higher erosion and runoff under CT. The highest losses, 1.3% of applied in CT and 0.22% of applied in ST, were observed during rainfall simulations conducted 1 DAT. Fluometuron runoff from natural rainfall was substantially lower from ST than from CT plots but the trend was reversed in rainfall simulations. In all studies, Fluometuron runoff was also relatively low (
Robert M Zablotowicz - One of the best experts on this subject based on the ideXlab platform.
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ORIGINAL PAPER
2015Co-Authors: Robert M Zablotowicz, Martin A. Locke, Lewis A. GastonAbstract:Tillage and cover effects on soil microbial properties and Fluometuron degradatio
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Fluometuron Interactions in Crop Residue-Managed Soils
2015Co-Authors: Martin A. Locke, Robert M Zablotowicz, Lewis A. GastonAbstract:This paper reviews a series of studies concerning Fluometuron (N,N-dimethyl-N'-[3-(trifluoromethyl)-phenyl]urea) interac tions in soil and herbicide-desiccated crop residues. The objective of these studies was to evaluate effects of tillage and cover crop management on Fluometuron sorption and degradation. Length of equilibration time and organic C level appeared to be the dominant factors influencing Fluometuron sorption quantity and kinetics. Related to these factors, resident time and plant surface accumulation of organic residues may influence the potential for subsequent movement in soil. Fall-seeded ryegrass (Lolium multiforum) cover in a cotton (Gossypium hirsutum L.) cropping system enhanced biological soil quality and the poten tial for Fluometuron degradation. Fluometuron was more rapidly degraded in annual ryegrass residues and conventional tillage (CT) or no-tillage (NT) soils under a fall-seeded annual ryegrass cover crop than in soils without residue
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constructed wetlands as a component of the agricultural landscape mitigation of herbicides in simulated runoff from upland drainage areas
Chemosphere, 2011Co-Authors: Martin A. Locke, Robert M Zablotowicz, Charles T Bryson, Mark A. Weaver, R W Steinriede, R F CullumAbstract:Constructed wetlands are a recommended practice for buffering pollutant source areas and receiving waters. A wetland consisting of a sediment trap and two treatment cells was constructed in a Mississippi Delta lake watershed. A 3-h simulated runoff event was initiated (2003) to evaluate fate and transport of atrazine and Fluometuron through the wetland. Water samples were collected during a runoff simulation and then afterward at selected intervals for 21 d, and analyzed for the herbicides. Breakthrough patterns for herbicide concentrations in water samples during the first 20 h after simulated runoff showed peak concentrations in the first 6 h, with gradual tailing as the herbicide pulse was diluted in the second, excavated (deeper) cell. Atrazine and Fluometuron concentrations in the first (shallower, non-excavated) cell averaged 12- and 20-fold greater, respectively, than those in the second cell following simulated runoff, indicating entrapment in the first cell. Atrazine and Fluometuron concentrations in the shallower cell decreased 32% and 22%, respectively, 9 d following simulated runoff, indicating either degradation or sorption to soil or wetland flora. In the excavated cell, concentrations were even lower, and atrazine declined more rapidly than Fluometuron. Results indicate constructed wetlands can improve downstream water quality though sequestration or processing of pollutants.
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Influence of watershed system management on herbicide concentrations in Mississippi Delta oxbow lakes.
Science of The Total Environment, 2006Co-Authors: Robert M Zablotowicz, Martin A. Locke, L. Jason Krutz, Robert N. Lerch, Richard E. Lizotte, Scott S. Knight, R. Earl Gordon, R. Wade SteinriedeAbstract:The Mississippi Delta Management Systems Evaluation Area (MD-MSEA) project was established in 1994 in three small watersheds (202 to 1497 ha) that drain into oxbow lakes (Beasley, Deep Hollow, and Thighman). The primary research objective was to assess the implications of management practices on water quality. Monthly monitoring of herbicide concentrations in lake water was conducted from 2000 to 2003. Water samples were analyzed for atrazine, cyanazine, Fluometuron, metolachlor, and atrazine metabolites. Herbicide concentrations observed in the lake water reflected cropping systems of the watershed, e.g., atrazine and metolachlor concentrations were associated with the level of corn and sorghum production, whereas cyanazine and Fluometuron was associated with the level of glyphosate-sensitive cotton production. The dynamics of herbicide appearance and dissipation in lake samples were strongly influenced by herbicide use, lake hydrology, rainfall pattern, and land management practices. The highest maximum concentrations of atrazine (7.1 to 23.4 μ gL �1 ) and metolachlor (0.7 to 14.9 μ gL �1 ) were observed in Thighman Lake where significant quantities of corn were grown. Introduction of s-metolachlor and use of glyphosateresistant cotton coincided with reduced concentration of metolachlor in lake water. Cyanazine was observed in two lakes with the highest levels (1.6 to 5.5 μ gL �1 ) in 2000 and lower concentrations in 2001 and 2002 (b0.4 μ gL �1 ). Reduced concentrations of Fluometuron in Beasley Lake were associated with greater use of glyphosate-resistant cotton and correspondingly less need for soilapplied Fluometuron herbicide. In contrast, increased levels of Fluometuron were observed in lake water after Deep Hollow was converted from conservation tillage to conventional tillage, presumably due to greater runoff associated with conventional tillage. These studies indicate that herbicide concentrations observed in these three watersheds were related to crop and soil management practices.
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Laboratory assessment of atrazine and Fluometuron degradation in soils from a constructed wetland.
Chemosphere, 2004Co-Authors: Mark A. Weaver, Robert M Zablotowicz, Martin A. LockeAbstract:Constructed wetlands offer promise for removal of nonpoint source contaminants such as herbicides from agricultural runoff. Laboratory studies assessed the potential of soils to degrade and sorb atrazine and Fluometuron within a recently constructed wetland. The surface 3 cm of soil was sampled from two cells of a Mississippi Delta constructed wetland; one shallow area disturbed only hydrologically, and the second excavated to provide greater water-holding capacity. The excavated area was more acidic on average (pH 4.85 versus 5.21), but otherwise the physical properties and general microbial enzyme activities in the two areas were similar. Soils were treated with 84 and 68l gk g � 1 soil 14 C-ring labeled atrazine and Fluometuron, respectively, and incubated under either saturated (88% moisture, w:w) or flooded (1 cm standing water) conditions. Soils were sampled over 32 days and extracted for herbicide and metabolite analysis. Under saturated conditions, Fluometuron metabolized to desmethylFluometuron (DMF) with a half-life equal 25–27 days. However, under flooded conditions, the half-life of Fluometuron was more than 175 days. Atrazine dissipated rapidly in saturated and flooded soil with a half-life of approximately 23 days, but only 10% of atrazine was mineralized to CO2. The overall atrazine and Fluometuron dissipation rates were similar between the two cells, but each area had a different pattern of metabolite accumulation. The major route of atrazine dissipation was incorporation of atrazine residues into methanol-nonextractable (soil-bound) components, with minimal extractable metabolite accumulation. A mixed-mode extractant (potassium phosphate:acetonitrile) recovered greater amounts of 14 C-residues from atrazine-treated soils, suggesting that hydrolysis of atrazine to
Thomas L Potter - One of the best experts on this subject based on the ideXlab platform.
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combined effects of constant versus variable intensity simulated rainfall and reduced tillage management on cotton preemergence herbicide runoff
Journal of Environmental Quality, 2006Co-Authors: Thomas L Potter, Clint C Truman, Timothy C Strickland, D D Bosch, Theodore M Webster, Dorcas H Franklin, Craig W BednarzAbstract:Pesticide runoff research relies heavily on rainfall simulation experiments. Most are conducted at a constant intensity, i.e., at a fixed rainfall rate; however, large differences in natural rainfall intensity is common. To assess implications we quantified runoff of two herbicides, Fluometuron and pendimethalin, and applied preemergence after planting cotton on Tifton loamy sand. Rainfall at constant and variable intensity patterns representative of late spring thunderstorms in the Atlantic Coastal Plain region of Georgia (USA) were simulated on 6-m 2 plots under strip- (ST) and conventional-tillage (CT) management. The variable pattern produced significantly higher runoff rates of both compounds from CT but not ST plots. However, on an event-basis, runoff totals (% applied) were not significantly different, with one exception: Fluometuron runoff from CT plots. There was about 25% more Fluometuron runoff with the variable versus the constant intensity pattern (P 5 0.10). Study results suggest that conduct of simulations using variable intensity storm patterns may provide more representative rainfall simulation-based estimates of pesticide runoff and that the greatest impacts will be observed with CT. The study also found significantly more Fluometuron in runoff from ST than CT plots. Further work is needed to determine whether this behavior may be generalized to other active ingredients with similar properties [low Koc (organic carbon partition coefficient) |100 mL g 21 ; high water solubility |100 mg L 21 ]. If so, it should be considered when making tillage-specific herbicide recommendations to reduce runoff potential.
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Fluometuron and pendimethalin runoff from strip and conventionally tilled cotton in the southern atlantic coastal plain
Journal of Environmental Quality, 2004Co-Authors: Thomas L Potter, Clint C Truman, D D Bosch, Craig W BednarzAbstract:In the Atlantic Coastal Plain region of southern Georgia (USA), cotton (Gossypium hirsutum L.) acreage increased threefold in the past decade. To more effectively protect water quality in the region, best management practices are needed that reduce pesticide runoff from fields in cotton production. This study compared runoff of two herbicides, Fluometuron [N,N-dimethyl-N'-[3-(trifluoromethyl)-phenyl]-urea] and pendimethalin [N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitro-benzenamine], from plots in strip-tillage (ST) and conventional-tillage (CT) management near Tifton, GA. Rainfall simulations were conducted one day after preemergence herbicide applications to 0.0006-ha plots and runoff from 0.15-ha plots due to natural rainfall following preemergence pendimethalin and Fluometuron and postemergence Fluometuron use was monitored. Pendimethalin runoff was greater under CT than ST due to strong pendimethalin soil sorption and higher erosion and runoff under CT. The highest losses, 1.3% of applied in CT and 0.22% of applied in ST, were observed during rainfall simulations conducted 1 DAT. Fluometuron runoff from natural rainfall was substantially lower from ST than from CT plots but the trend was reversed in rainfall simulations. In all studies, Fluometuron runoff was also relatively low (<1% of applied), and on plots under natural rainfall, desmethylFluometuron (DMF) represented about 50% of total Fluometuron runoff. Fluometuron's relatively low runoff rate appeared linked to its rapid leaching, and high DMF detection rates in runoff support DMF inclusion in Fluometuron risk assessments. Results showed that ST has the potential to reduce runoff of both herbicides, but Fluometuron leaching may be a ground water quality concern.
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Fluometuron and pendimethalin runoff from strip and conventionally tilled cotton in the southern atlantic coastal plain.
Journal of environmental quality, 2004Co-Authors: Thomas L Potter, Clint C Truman, D D Bosch, Craig W BednarzAbstract:In the Atlantic Coastal Plain region of southern Georgia (USA), cotton (Gossypium hirsutum L.) acreage increased threefold in the past decade. To more effectively protect water quality in the region, best management practices are needed that reduce pesticide runoff from fields in cotton production. This study compared runoff of two herbicides, Fluometuron [N,N-dimethyl-N'-[3-(trifluoromethyl)-phenyl]-urea] and pendimethalin [N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitro-benzenamine], from plots in strip-tillage (ST) and conventional-tillage (CT) management near Tifton, GA. Rainfall simulations were conducted one day after preemergence herbicide applications to 0.0006-ha plots and runoff from 0.15-ha plots due to natural rainfall following preemergence pendimethalin and Fluometuron and postemergence Fluometuron use was monitored. Pendimethalin runoff was greater under CT than ST due to strong pendimethalin soil sorption and higher erosion and runoff under CT. The highest losses, 1.3% of applied in CT and 0.22% of applied in ST, were observed during rainfall simulations conducted 1 DAT. Fluometuron runoff from natural rainfall was substantially lower from ST than from CT plots but the trend was reversed in rainfall simulations. In all studies, Fluometuron runoff was also relatively low (
Charles E. Snipes - One of the best experts on this subject based on the ideXlab platform.
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influence of cultivation timing on pyrithiobac performance in cotton gossypium hirsutum 1
Weed Technology, 2000Co-Authors: Eric P. Webster, David R Shaw, Todd A. Baughman, Charles E. Snipes, Charles T BrysonAbstract:Abstract: Pitted morningglory control with norflurazon or Fluometuron preemergence (PRE), each at 1.12 kg/ha, was 72% or less 14 d after a postemergence (POST) application of pyrithiobac in 1993 and 1994. Pyrithiobac POST at 70 g/ha following Fluometuron or norflurazon PRE cultivated at any timing controlled pitted morningglory at least 76%. Pyrithiobac POST controlled common cocklebur equal to the weed-free in 1993 at 14 d after the POST application. In 1994, when rated 28 d after pyrithiobac POST, cultivation 3 d before a single application of pyrithiobac controlled less common cocklebur than any other herbicide treatment containing pyrithiobac. At 28 d after pyrithiobac POST, no treatment controlled common cocklebur as well as the weed-free. In 1993 and 1994, seed cotton yield was equal to the weed-free when pyrithiobac followed Fluometuron PRE cultivated at any timing or a single application of pyrithiobac cultivated prior to 7 d after POST application. Nomenclature: Fluometuron, N,N′-dimethyl-N′-[3-(...
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Adsorption, dissipation, and movement of Fluometuron in three southeastern United States soils.
Weed Science, 1997Co-Authors: William T. Willian, Robert M. Hayes, Thomas C. Mueller, Charles E. Snipes, David C. BridgesAbstract:Fluometuron adsorption and dissipation under field and laboratory conditions, and distribution within the soil profile was determined in 3 soils from Tennessee, Mississippi, and Georgia that are representative of the cotton-growing regions of the southeastern United States. Fluometuron adsorption was correlated with organic matter, but not with clay content or soil pH. First-order kinetics explained Fluometuron dissipation under field and controlled conditions (r2≥ 0.82). Field dissipation of Fluometuron was slower under dry conditions. Fluometuron was not detected below 15 cm in the soil profile in any soil, and concentrations in the 8- to 15-cm soil zone were < 15 ppbw 112 d after treatment. Fluometuron dissipation was more rapid in soil from the 0- to 8-cm depth in Tennessee soil than in Mississippi soil under controlled conditions. Dissipation was more rapid under field conditions than under laboratory conditions at 2 of 3 locations. Fluometuron half-lives in soils from the 0- to 8-cm depth ranged from 9 to 28 d under field conditions and from 11 to 43 d in the laboratory. Fluometuron dissipation in soils from 30- to 45- and 60- to 90-cm depths was not different among soils, with half-lives ranging from 58 to 99 d under laboratory conditions. Fluometuron half-life was positively correlated with soil depth and inversely correlated with organic matter. These data indicate that organic matter, soil depth, and environmental conditions affect Fluometuron dissipation.
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The Influence of Fluometuron and MSMA on Cotton Yield and Fruiting Characteristics1
Weed Science, 1994Co-Authors: Charles E. Snipes, J. D. ByrdAbstract:Field experiments conducted from 1987 through 1991 at the Delta Branch Experiment Station, Stoneville, MS, determined the effect of postemergence topical applications of Fluometuron and MSMA on cotton yield and fruiting. Herbicide treatments applied to cotton in the cotyledon to 1-leaf growth stage were 1.12 kg ai ha-' Fluometuron plus 0.25 % by vol nonionic surfactant, 2.2 kg ai ha-' MSMA, and a combination of 1.12 kg ha-' Fluometuron and 2.24 kg ha-' MSMA. The commercial formulation of MSMA contained nonionic surfactant. Visual injury of cotton 14 d after treat- ment ranged from 14 to 28% for Fluometuron, 9 to 26% for MSMA, and 22 to 34 % for the combination. Seed cotton yield at the first harvest was reduced by all herbicide treatments except in 1987 and for DES 119 cotton in 1990. In 1990, yield of DES 119 cotton treated with MSMA and the combination was less than the untreated control for the second harvest interval. Cotton yield from herbicide treatments at later harvests was equal to or greater than the untreated control. Only in 1988 did all treatments reduce total seed cotton yield below the untreated control. Fiber quality was not adversely affected by the herbicides. Compared to the control, plant mapping indicated that the number of sympodial branches per plant was reduced by MSMA and by the combination for DPL 50 cotton in 1990. Averaged over 4 experiment years, herbicide treatments did not reduce total bolls per plant; percentage of boils in first, second, or outer positions; highest sympodium with two bolls; or number of sympodium with bolls in the first or second position. However, MSMA and the combination increased node number of the first sympodia by one and 1.5 positions, respectively, when compared to the control, indicating delayed maturity. Nomenclature: F I u o m e t u r o n, N,N-dinethyl-N'-(3-(trifluoromethyl)- phenyl)urea; MSMA, monosodium salt of methylarsonic acid; cotton, Gossypium hirsutum L., 'DES 422,"DES 119,' and 'DPL 50.' Additional index words: Plant mapping, fiber quality, mi- cronaire, maturity, herbicide phytotoxicity, COTMAP.
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cotton gossypium hirsutum yield response to mechanical and chemical weed control systems
Weed Science, 1992Co-Authors: Charles E. Snipes, Thomas C MuelleAbstract:Cotton yield response was evaluated in 1987, 1988, and 1989 when weeds were managed with preemergence Fluometuron [none (0%), band (50%), or broadcast (100%) surface coverage], cultivation (none, one, two, or three times), and postdirected Fluometuron + MSMA. Weed densities (primarily prickly sida, morningglories, and hemp sesbania) varied widely among years and were directly related to early season rainfall. Postdirected herbicide application or cultivation(s) had little effect on weed density. The use of a banded Fluometuron application reduced weed biomass 28 to 47%. A further decrease was observed when preemergence Fluometuron was increased from banded to broadcast coverage. Seed cotton yields were low with no preemergence Fluometuron. Banded Fluometuron and at least one cultivation had yields similar to broadcast Fluometuron only. Cotton yields were related to weed density and weed biomass in a hyperbolic relationship. Low weed densities caused more yield loss per unit weed density than higher densities. Nomenclature: Fluometuron, N,N-dimethyl-N'-[3(trifluoromethyl)phenyl]urea; MSMA, monosodium salt of methylarsonic acid; cotton, Gossypium hirsutum L. 'DES 119'; prickly sida, Sida spinosa #3 SIDSP; hemp sesbania, Sesbania exaltata # SEBEX; morningglories, Ipomoea species # IPOZZ. Additional index words. Weed competition, yield loss, weed density, weed biomass, interference, SIDSP, IPOZZ, SEBEX.
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Cotton (Gossypium hirsutum) Yield Response to Mechanical and Chemical Weed Control Systems
Weed Science, 1992Co-Authors: Charles E. Snipes, Thomas C. MuellerAbstract:Cotton yield response was evaluated in 1987, 1988, and 1989 when weeds were managed with preemergence Fluometuron [none (0%), band (50%), or broadcast (100%) surface coverage], cultivation (none, one, two, or three times), and postdirected Fluometuron + MSMA. Weed densities (primarily prickly sida, morningglories, and hemp sesbania) varied widely among years and were directly related to early season rainfall. Postdirected herbicide application or cultivation(s) had little effect on weed density. The use of a banded Fluometuron application reduced weed biomass 28 to 47%. A further decrease was observed when preemergence Fluometuron was increased from banded to broadcast coverage. Seed cotton yields were low with no preemergence Fluometuron. Banded Fluometuron and at least one cultivation had yields similar to broadcast Fluometuron only. Cotton yields were related to weed density and weed biomass in a hyperbolic relationship. Low weed densities caused more yield loss per unit weed density than higher densities.