Palmer amaranth, sicklepod and pitted morningglory are the three most common and troublesome weeds in soybean in South Carolina. They exhibit very aggressive growth capabilities and if left uncontrolled in fields will...Palmer amaranth, sicklepod and pitted morningglory are the three most common and troublesome weeds in soybean in South Carolina. They exhibit very aggressive growth capabilities and if left uncontrolled in fields will cause significant reductions in soybean yields. Dicamba and 2,4-D herbicides are currently having a resurgence in usage due to the recent commercialization of soybean trait technologies with tolerance to these herbicides. Dicamba and 2,4-D when tank mixed with glufosinate and glyphosate may offer additional weed control to resistant weeds through the process of herbicide synergism. Greenhouse experiments were conducted in 2013 at Edisto Research and Education Center near Blackville, SC to evaluate the efficacy of glyphosate, glufosinate, dicamba and 2,4-D treatments alone and in combination on Palmer amaranth, sicklepod, and pitted morningglory at selected heights. Results suggested that glufosinate alone provided the overall best control for all 3 weed species. Glyphosate alone provided the lowest control of all 3 species at all heights. Synergism or improved sicklepod control was observed when glufosinate was tank mixed with dicamba. However, as sicklepod increased in height, glufosinate + 2,4-D or dicamba combination offered the best control compared to glufosinate alone (90% versus 86% in 20 cm plants and 87% versus 85% in 30 cm plant). In the 5 cm Palmer amaranth, decreased control was observed when glyphosate or glufosinate was tank mixed with 2,4-D. These experiments showed that glufosinate alone and/or in combination with 2,4-D or dicamba was the overall best treatment on the three broadleaf weed species.展开更多
Palmer amaranth and pitted morningglory are difficult to manage weeds present in South Carolina soybean production fields. Glyphosate and ALS-resistant Palmer amaranth biotypes have spread rapidly throughout South Car...Palmer amaranth and pitted morningglory are difficult to manage weeds present in South Carolina soybean production fields. Glyphosate and ALS-resistant Palmer amaranth biotypes have spread rapidly throughout South Carolina making the control of these weeds more difficult. Recently, soybean varieties with tolerance to dicamba have been introduced along with several new ultra-low volatility formulations of dicamba to help with the problem. Field experiments were conducted near Blackville, SC in 2012 and 2013 to evaluate dicamba herbicide programs for broadleaf weed management in dicamba tolerant soybean. At 2 weeks after POST1 (2 WAP1), Palmer amaranth control ranged from 93% to 100% across the PRE followed by POST treatments in 2012 and 2013. By 2 weeks after POST2 (2 WAP2), control was 95% or better. Treatments containing two or three herbicide applications (PRE, POST1 and POST2) offered good to excellent (92% - 100%) pitted morningglory control. No differences in weed control were observed among treatments with 3 application times compared to those applied twice. In general, all treatments with a PRE followed by at least one POST application provided good to excellent control of Palmer amaranth and pitted morningglory. Overall, a PRE (either dicamba or flumioxazin) followed by a dicamba or a non-dicamba containing POST treatment provided good to excellent control of Palmer amaranth and pitted morningglory when applied at the correct growth stage.展开更多
The use of transgenic crops has grown significantly over the past couple of decades. Many agronomic crops produced today are tolerant to glyphosate. Glyphosate-tolerant crops were commercially introduced in 1996, and,...The use of transgenic crops has grown significantly over the past couple of decades. Many agronomic crops produced today are tolerant to glyphosate. Glyphosate-tolerant crops were commercially introduced in 1996, and, about nine years later, glyphosate-resistant Palmer amaranth was confirmed in Georgia. Glyphosate-resistant weeds arose from reliance on postemergence only glyphosate programs to control weeds in crops. New transgenic traits for glufosinate and 2,4-D choline have been developed, and evaluations of stacked traits and concurrent use of multiple herbicides have provided additional tools in the management of glyphosate-resistant weeds. Field experiments were conducted in 2012 and 2013 at the Edisto Research and Education Center near Blackville, SC, USA to determine the efficacy of 2,4-D-based herbicide programs in transgenic cotton tolerant to 2,4-D choline, glyphosate, and glufosinate. The treatments provided good to excellent Palmer amaranth and pitted morningglory control in 2012 and 2013. Seed cotton yields across treatments ranged from 0 to 2057 kg ha-1. This new trait technology package in cotton permits in-season postemergence use of 2,4-D choline, a herbicide mode of action not previously used postemergence in cotton, which can control resistant weeds, including Palmer amaranth if applied at the proper growth stage.展开更多
Weeds are the most limiting factor in soybean production in South Carolina. With early emergence and rapid growth, weeds effectlively compete for water, nutrients, and light resources. The recent evolution of herbicid...Weeds are the most limiting factor in soybean production in South Carolina. With early emergence and rapid growth, weeds effectlively compete for water, nutrients, and light resources. The recent evolution of herbicide resistant weeds has made it increasingly difficult for growers to effectively control weeds in soybean. Glyphosate and ALS-resistant Palmer amaranth biotypes have spread rapidly throughout South Carolina, especially in areas where resistance management is lacking. Soybean varieties have been recently developed with tolerance to 2,4-D. Field experiments were conducted at the Clemson University Edisto Research and Education Center located near Blackville, SC in 2012 and 2013 to evaluate selected 2,4-D choline based herbicide programs for weed management in 2,4-D tolerant soybean. Overall, all herbicide treatments were effective in controlling weeds at the POST2 timing. Palmer amaranth control was excellent;however, pitted morningglory was the most difficult. The 2,4-D plus glyphosate pre-mixture provided excellent control for all three weed species with >95% control at POST2 timing. In these treatments, the rate of 2,4-D choline plus glyphosate (1.09 kg ae ha-1 or 1.64 kg ae ha-1) did not have a significant effect on weed control (P = 0.3772). There was a decrease in pitted morningglory control 3 WAP in 2012 vs 2013 in plots treated with S-metolachlor + fomesafen because of a lack of activating soil moisture in 2012. Results from this study showed that all treatments evaluated provided good to excellent control of all 3 weed species. Based on the herbicide programs evaluated in the study, herbicide resistant weeds, such as Palmer amaranth, can be effectively controlled when treated at the correct growth stage.展开更多
文摘Palmer amaranth, sicklepod and pitted morningglory are the three most common and troublesome weeds in soybean in South Carolina. They exhibit very aggressive growth capabilities and if left uncontrolled in fields will cause significant reductions in soybean yields. Dicamba and 2,4-D herbicides are currently having a resurgence in usage due to the recent commercialization of soybean trait technologies with tolerance to these herbicides. Dicamba and 2,4-D when tank mixed with glufosinate and glyphosate may offer additional weed control to resistant weeds through the process of herbicide synergism. Greenhouse experiments were conducted in 2013 at Edisto Research and Education Center near Blackville, SC to evaluate the efficacy of glyphosate, glufosinate, dicamba and 2,4-D treatments alone and in combination on Palmer amaranth, sicklepod, and pitted morningglory at selected heights. Results suggested that glufosinate alone provided the overall best control for all 3 weed species. Glyphosate alone provided the lowest control of all 3 species at all heights. Synergism or improved sicklepod control was observed when glufosinate was tank mixed with dicamba. However, as sicklepod increased in height, glufosinate + 2,4-D or dicamba combination offered the best control compared to glufosinate alone (90% versus 86% in 20 cm plants and 87% versus 85% in 30 cm plant). In the 5 cm Palmer amaranth, decreased control was observed when glyphosate or glufosinate was tank mixed with 2,4-D. These experiments showed that glufosinate alone and/or in combination with 2,4-D or dicamba was the overall best treatment on the three broadleaf weed species.
文摘Palmer amaranth and pitted morningglory are difficult to manage weeds present in South Carolina soybean production fields. Glyphosate and ALS-resistant Palmer amaranth biotypes have spread rapidly throughout South Carolina making the control of these weeds more difficult. Recently, soybean varieties with tolerance to dicamba have been introduced along with several new ultra-low volatility formulations of dicamba to help with the problem. Field experiments were conducted near Blackville, SC in 2012 and 2013 to evaluate dicamba herbicide programs for broadleaf weed management in dicamba tolerant soybean. At 2 weeks after POST1 (2 WAP1), Palmer amaranth control ranged from 93% to 100% across the PRE followed by POST treatments in 2012 and 2013. By 2 weeks after POST2 (2 WAP2), control was 95% or better. Treatments containing two or three herbicide applications (PRE, POST1 and POST2) offered good to excellent (92% - 100%) pitted morningglory control. No differences in weed control were observed among treatments with 3 application times compared to those applied twice. In general, all treatments with a PRE followed by at least one POST application provided good to excellent control of Palmer amaranth and pitted morningglory. Overall, a PRE (either dicamba or flumioxazin) followed by a dicamba or a non-dicamba containing POST treatment provided good to excellent control of Palmer amaranth and pitted morningglory when applied at the correct growth stage.
文摘The use of transgenic crops has grown significantly over the past couple of decades. Many agronomic crops produced today are tolerant to glyphosate. Glyphosate-tolerant crops were commercially introduced in 1996, and, about nine years later, glyphosate-resistant Palmer amaranth was confirmed in Georgia. Glyphosate-resistant weeds arose from reliance on postemergence only glyphosate programs to control weeds in crops. New transgenic traits for glufosinate and 2,4-D choline have been developed, and evaluations of stacked traits and concurrent use of multiple herbicides have provided additional tools in the management of glyphosate-resistant weeds. Field experiments were conducted in 2012 and 2013 at the Edisto Research and Education Center near Blackville, SC, USA to determine the efficacy of 2,4-D-based herbicide programs in transgenic cotton tolerant to 2,4-D choline, glyphosate, and glufosinate. The treatments provided good to excellent Palmer amaranth and pitted morningglory control in 2012 and 2013. Seed cotton yields across treatments ranged from 0 to 2057 kg ha-1. This new trait technology package in cotton permits in-season postemergence use of 2,4-D choline, a herbicide mode of action not previously used postemergence in cotton, which can control resistant weeds, including Palmer amaranth if applied at the proper growth stage.
文摘Weeds are the most limiting factor in soybean production in South Carolina. With early emergence and rapid growth, weeds effectlively compete for water, nutrients, and light resources. The recent evolution of herbicide resistant weeds has made it increasingly difficult for growers to effectively control weeds in soybean. Glyphosate and ALS-resistant Palmer amaranth biotypes have spread rapidly throughout South Carolina, especially in areas where resistance management is lacking. Soybean varieties have been recently developed with tolerance to 2,4-D. Field experiments were conducted at the Clemson University Edisto Research and Education Center located near Blackville, SC in 2012 and 2013 to evaluate selected 2,4-D choline based herbicide programs for weed management in 2,4-D tolerant soybean. Overall, all herbicide treatments were effective in controlling weeds at the POST2 timing. Palmer amaranth control was excellent;however, pitted morningglory was the most difficult. The 2,4-D plus glyphosate pre-mixture provided excellent control for all three weed species with >95% control at POST2 timing. In these treatments, the rate of 2,4-D choline plus glyphosate (1.09 kg ae ha-1 or 1.64 kg ae ha-1) did not have a significant effect on weed control (P = 0.3772). There was a decrease in pitted morningglory control 3 WAP in 2012 vs 2013 in plots treated with S-metolachlor + fomesafen because of a lack of activating soil moisture in 2012. Results from this study showed that all treatments evaluated provided good to excellent control of all 3 weed species. Based on the herbicide programs evaluated in the study, herbicide resistant weeds, such as Palmer amaranth, can be effectively controlled when treated at the correct growth stage.
