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Phillip W. Stahlman - One of the best experts on this subject based on the ideXlab platform.
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Herbicide options for glyphosate-resistant Kochia (Bassia scoparia) management in the Great Plains
Weed Technology, 2019Co-Authors: Gustavo M. Sbatella, Phillip W. Stahlman, Andrew R. Kniss, Albert T. Adjesiwor, Phil Westra, Michael Moechnig, Robert G. WilsonAbstract:Kochia is one of the most problematic weeds in the United States. Field studies were conducted in five states (Wyoming, Colorado, Kansas, Nebraska, and South Dakota) over 2 yr (2010 and 2011) to evaluate Kochia control with selected herbicides registered in five common crop scenarios: winter wheat, fallow, corn, soybean, and sugar beet to provide insight for diversifying Kochia management in crop rotations. Kochia control varied by experimental site such that more variation in Kochia control and biomass production was explained by experimental site than herbicide choice within a crop. Kochia control with herbicides currently labeled for use in sugar beet averaged 32% across locations. Kochia control was greatest and most consistent from corn herbicide programs (99%), followed by soybean (96%) and fallow (97%) herbicide programs. Kochia control from wheat herbicide programs was 93%. With respect to the availability of effective herbicide options, glyphosate-resistant Kochia control was easiest in corn, soybean, and fallow, followed by wheat; and difficult to manage with herbicides in sugar beet. Nomenclature: Glyphosate; Kochia, Bassia scoparia (L.) A. J. Scott, KCHSC; corn, Zea mays L. ZEAMX; soybean, Glycine max (L.) Merr. GLXMA; sugar beet, Beta vulgaris L. BEAVX; wheat, Triticum aestivum L. TRZAX
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Dicamba-resistant Kochia (Bassia scoparia) in Kansas: characterization and management with fall- or spring-applied PRE herbicides
Weed Technology, 2019Co-Authors: Vipan Kumar, Phillip W. Stahlman, Prashant Jha, Randall S. Currie, Ryan P. Engel, Curtis R. ThompsonAbstract:Dicamba-resistant (DR) Kochia is an increasing concern for growers in the US Great Plains, including Kansas. Greenhouse and field experiments (Garden City and Tribune, KS, in the 2014 to 2015 growing season) were conducted to characterize the dicamba resistance levels in two recently evolved DR Kochia accessions collected from fallow fields (wheat–sorghum–fallow rotation) near Hays, KS, and to determine the effectiveness of various PRE herbicide tank mixtures applied in fall or spring prior to the fallow year. Dicamba dose–response studies indicated that the KS-110 and KS-113 accessions had 5- to 8-fold resistance to dicamba, respectively, relative to a dicamba-susceptible (DS) accession. In separate field studies, atrazine-based PRE herbicide tank mixtures, dicamba + pendimethalin + sulfentrazone, and metribuzin + sulfentrazone when applied in the spring had excellent Kochia control (85% to 95%) for 3 to 4 mo at the Garden City and Tribune sites. In contrast, Kochia control with those PRE herbicide tank mixtures when applied in the fall did not exceed 79% at the later evaluation dates. In conclusion, the tested Kochia accessions from western Kansas had evolved moderate to high levels of resistance to dicamba. Growers should utilize these effective PRE herbicide tank mixtures (multiple sites of action) in early spring to manage Kochia seed bank during the summer fallow phase of this 3-yr crop rotation (wheat–corn/sorghum–fallow) in the Central Great Plains.
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first report of Kochia bassia scoparia with cross resistance to dicamba and fluroxypyr in western kansas
Weed Technology, 2019Co-Authors: Vipan Kumar, Prashant Jha, Randall S. Currie, Phillip W. StahlmanAbstract:Evolution and rapid spread of herbicide-resistant (HR) Kochia has become a significant challenge for growers in the U.S. Great Plains. The main objectives of this research were to confirm and characterize the response of putative auxinic HR (Aux-HR) Kochia accessions (designated as KS-4A, KS-4D, KS-4H, KS-10A, KS-10-G, and KS-10H) collected from two different corn fields near Garden City, KS, to dicamba and fluroxypyr and to determine the EPSPS gene copy number to detect whether those accessions were also resistant to glyphosate. Single-dose experiments indicated that putative Aux-HR Kochia accessions had 78% to 100% and 85% to 100% survivors when treated with dicamba (560 g ae ha−1) and fluroxypyr (235 g ae ha−1), respectively. Whole-plant dicamba dose–response studies revealed that the selected Aux-HR accessions had 2.9- to 15.1- and 3.1- to 9.4-fold resistance to dicamba relative to two susceptible accessions (MT-SUS and KS-SUS). In a separate fluroxypyr dose–response experiment, the selected Aux-HR accessions also exhibited 3.8- to 7.3- and 3.0- to 8.6-fold resistance to fluroxypyr on the basis of shoot fresh and dry weight responses, respectively. The confirmed Aux-HR Kochia accessions also had 3 to 13 EPSPS gene copies relative to MT-SUS and KS-SUS accessions (each with 1 EPSPS gene copy). These results suggest that the putative Aux-HR Kochia accessions from Kansas had developed moderate to high levels of cross-resistance to dicamba and fluroxypyr and low to high levels of resistance to glyphosate. This is the first confirmation of Kochia accessions with cross-resistance to dicamba and fluroxypyr in Kansas. Growers should use diverse Kochia control programs, including the proper use of dicamba and fluroxypyr stewardship, use of cover crops, occasional tillage, diversified crop rotations, and alternative effective herbicides to prevent further evolution and spread of Aux-HR Kochia on their fields.
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First Report of Kochia (Bassia scoparia) with Cross-Resistance to Dicamba and Fluroxypyr in Western Kansas
Weed Technology, 2019Co-Authors: Vipan Kumar, Prashant Jha, Randall S. Currie, Phillip W. StahlmanAbstract:Evolution and rapid spread of herbicide-resistant (HR) Kochia has become a significant challenge for growers in the U.S. Great Plains. The main objectives of this research were to confirm and characterize the response of putative auxinic HR (Aux-HR) Kochia accessions (designated as KS-4A, KS-4D, KS-4H, KS-10A, KS-10-G, and KS-10H) collected from two different corn fields near Garden City, KS, to dicamba and fluroxypyr and to determine the EPSPS gene copy number to detect whether those accessions were also resistant to glyphosate. Single-dose experiments indicated that putative Aux-HR Kochia accessions had 78% to 100% and 85% to 100% survivors when treated with dicamba (560 g ae ha – ¹) and fluroxypyr (235 g ae ha–¹), respectively. Whole-plant dicamba dose–response studies revealed that the selected Aux-HR accessions had 2.9- to 15.1- and 3.1- to 9.4-fold resistance to dicamba relative to two susceptible accessions (MT-SUS and KS-SUS). In a separate fluroxypyr dose–response experiment, the selected Aux-HR accessions also exhibited 3.8- to 7.3- and 3.0- to 8.6-fold resistance to fluroxypyr on the basis of shoot fresh and dry weight responses, respectively. The confirmed Aux-HR Kochia accessions also had 3 to 13 EPSPS gene copies relative to MT-SUS and KS-SUS accessions (each with 1 EPSPS gene copy). These results suggest that the putative Aux-HR Kochia accessions from Kansas had developed moderate to high levels of cross-resistance to dicamba and fluroxypyr and low to high levels of resistance to glyphosate. This is the first confirmation of Kochia accessions with cross-resistance to dicamba and fluroxypyr in Kansas. Growers should use diverse Kochia control programs, including the proper use of dicamba and fluroxypyr stewardship, use of cover crops, occasional tillage, diversified crop rotations, and alternative effective herbicides to prevent further evolution and spread of Aux-HR Kochia on their fields. Nomenclature: Dicamba; fluroxypyr; glyphosate; Kochia, Bassia scoparia (L.) A. J. Scott
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reduced absorption of glyphosate and decreased translocation of dicamba contribute to poor control of Kochia Kochia scoparia at high temperature
Pest Management Science, 2018Co-Authors: Phillip W. Stahlman, Mithila JugulamAbstract:BACKGROUND Plant growth temperature is one of the important factors that can influence postemergent herbicide efficacy and impact weed control. Control of Kochia (Kochia scoparia), a major broadleaf weed throughout the North American Great Plains, often is unsatisfactory when either glyphosate or dicamba are applied on hot summer days. We tested effects of plant growth temperature on glyphosate and dicamba phytotoxicity on two Kansas Kochia populations (P1 and P2) grown under the following three day/night (d/n) temperature regimes: T1, 17.5/7.5°C; T2, 25/15°C; and T3, 32.5/22.5°C. RESULTS Visual injury and above-ground dry biomass data from herbicide dose–response experiments indicated greater susceptibility to both glyphosate and dicamba when Kochia was grown under the two cooler temperature regimes, i.e. T1 and T2. At T1, the ED50 of P1 and P2 Kochia were 39 and 36 g ha−1 of glyphosate and 52 and 105 g ha−1 of dicamba, respectively. In comparison, at T3 the ED50 increased to 173 and 186 g ha−1 for glyphosate and 106 and 410 g ha−1 for dicamba, respectively, for P1 and P2. We also investigated the physiological basis of decreased glyphosate and dicamba efficacy under elevated temperatures. Kochia absorbed more glyphosate at T1 and T2 compared to T3. Conversely, there was more dicamba translocated towards meristems at T1 and T2, compared to T3. CONCLUSION Reduced efficacy of dicamba or glyphosate to control Kochia under elevated temperatures can be attributed to decreased absorption and translocation of glyphosate and dicamba, respectively. Therefore, it is recommended to apply glyphosate or dicamba when the temperature is low (e.g. d/n temperature at 25/15°C) and seedlings are small (less than 12 cm) to maximize Kochia control. © 2016 Society of Chemical Industry
Hugh J. Beckie - One of the best experts on this subject based on the ideXlab platform.
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high gene flow maintains genetic diversity following selection for high epsps copy number in the weed Kochia amaranthaceae
Scientific Reports, 2020Co-Authors: Sara L Martin, Hugh J. Beckie, Leshawn Benedict, Connie A Sauder, Wei Wei, Linda M HallAbstract:Kochia, a major weed species, has evolved resistance to four herbicide modes of action. Herbicide resistance appears to spread quickly, which could result in diminished standing genetic variation, reducing the ability of populations to adapt further. Here we used double digest restriction enzyme associated sequencing to determine the level of gene flow among Kochia populations and whether selection for glyphosate resistance reduces genetic variation. Canadian Prairie populations show little to no genetic differentiation (FST = 0.01) and no correlation between genetic and geographic distance (r2 = - 0.02 p = 0.56), indicating high gene flow and no population structure. There is some evidence that Kochia populations are genetically depauperate compared to other weed species, but genetic diversity did not differ between glyphosate susceptible and resistant populations or individuals. The inbreeding coefficients suggest there are 23% fewer heterozygotes in these populations than expected with random mating, and no variation was found within the chloroplast. These results indicate that any alleles for herbicide resistance can be expected to spread quickly through Kochia populations, but there is little evidence this spread will reduce the species' genetic variation or limit the species' ability to respond to further selection pressure.
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glyphosate resistance reduces Kochia fitness comparison of segregating resistant and susceptible f2 populations
Plant Science, 2017Co-Authors: Sara L Martin, Leshawn Benedict, Connie A Sauder, Wei Wei, Leandro Oliveira Da Costa, Linda M Hall, Hugh J. BeckieAbstract:Abstract Glyphosate is considered the world’s most important herbicide, but widespread and continual use has resulted in the evolution of resistance. Kochia scoparia (Kochia) has evolved resistance via tandem gene amplification of glyphosate’s target, 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) and resistant populations have been reported from the Canadian Prairies and the Northern Great Plains. Here, we evaluated the fitness costs of EPSPS amplification in Kochia by comparing susceptible and resistant full siblings from segregating F2 populations generated from within six populations. Kochia was expected to be highly diverse because of strong gene flow; however, six of the seven field-collected parents with higher EPSPS copy number were homozygous. Under competitive greenhouse conditions, the EPSPS type of the line’s maternal parent showed persistent effects: delayed emergence, delayed flowering, and reductions in viable seed count and weight overall. High EPSPS copy number individuals had reduced seed count and weight, reduced competitive ability, and reduced final height in mixed stands, but better germination of the F3. However, all characteristics were highly variable and fitness costs were not constant across genetic backgrounds. In the absence of selection from glyphosate, Kochia with increased EPSPS copy number will be at a competitive disadvantage in some genetic backgrounds.
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pollen and seed mediated gene flow in Kochia Kochia scoparia
Weed Science, 2016Co-Authors: Hugh J. Beckie, Linda M Hall, Robert E Blackshaw, Eric N JohnsonAbstract:Efficient natural dispersal of herbicide-resistance alleles via seed and pollen can markedly accelerate the incidence of herbicide-resistant weed populations across an agroecoregion. Studies were conducted in western Canada in 2014 and 2015 to investigate pollen- and seed-mediated gene flow in Kochia. Pollen-mediated gene flow (PMGF) from glyphosate-resistant (GR) to non-GR Kochia was quantified in a field trial (hub and spoke design) at Saskatoon, Saskatchewan. Seed-mediated gene flow of acetolactate synthase (ALS) inhibitor-resistant Kochia as a function of tumbleweed speed and distance was estimated in cereal stubble fields at Lethbridge, Alberta and Scott, Saskatchewan. Regression analysis indicated that outcrossing from GR to adjacent non-GR Kochia ranged from 5.3 to 7.5%, declining exponentially to 0.1 to 0.4% at 96 m distance. However, PMGF was significantly influenced by prevailing wind direction during pollination (maximum of 11 to 17% outcrossing down-wind). Seed dropped by tumbleweeds varied wi...
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Response of glyphosate-resistant Kochia (Kochia scoparia L. Schrad.) to alternative herbicides
Canadian Journal of Plant Science, 2014Co-Authors: Nikki Burton, Scott W. Shirriff, Hugh J. BeckieAbstract:Burton, N., Shirriff, S. W. and Beckie, H. J. 2014. Response of glyphosate-resistant Kochia (Kochia scoparia L. Schrad.) to alternative herbicides. Can. J. Plant Sci. 94: 1407-1411. A greenhouse study was conducted to examine the response of glyphosate-resistant (GR) plus acetolactate synthase (ALS) inhibitor-resistant Kochia to five post-emergence herbicide treatments commonly used to control the weed species in chemical fallow, cereals, or oilseed crops in western Canada. The treatments, which were applied to two GR Kochia biotypes and one non-GR (susceptible) biotype, included the labeled rate of dicamba, dicamba/fluroxypyr, dicamba/diflufenzopyr, MCPA/bromoxynil, and glufosinate. Both GR and non-GR biotypes responded similarly to each of the herbicide treatments. Although both GR biotypes were sensitive to the herbicides, MCPA/bromoxynil was the most effective treatment in reducing shoot biomass 3 wk after application (99%), followed by glufosinate (91%) then the dicamba mixtures (82%). Dicamba alone ...
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glyphosate and acetolactate synthase inhibitor resistant Kochia Kochia scoparia in western canada
Weed Science, 2013Co-Authors: Hugh J. Beckie, Sara L Martin, Connie A Sauder, Linda M Hall, Robert E Blackshaw, Ryan Low, Randall N Brandt, Scott W. ShirriffAbstract:Abstract In summer, 2011, we investigated suspected glyphosate-resistant (GR) Kochia in three chem-fallow fields (designated F1, F2, F3, each farmed by a different grower) in southern Alberta. This study characterizes glyphosate resistance in those populations, based on data from dose–response experiments. In a greenhouse experiment, the three populations exhibited a resistance factor ranging from 4 to 6 based on shoot biomass response (GR50 ratios), or 5 to 7 based on survival response (LD50 ratios). Similar results were found in a field dose–response experiment at Lethbridge, AB, in spring 2012 using the F2 Kochia population. In fall 2011, we surveyed 46 fields within a 20-km radius of the three chem-fallow fields for GR Kochia. In the greenhouse, populations were screened with glyphosate at 900 g ae ha−1. Seven populations were confirmed as GR, the farthest site located about 13 km from the three originally confirmed populations. An additional GR population more than 100 km away was later confirmed. Po...
Vipan Kumar - One of the best experts on this subject based on the ideXlab platform.
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herbicide programs to manage glyphosate dicamba resistant Kochia bassia scoparia in glyphosate dicamba resistant soybean
Weed Technology, 2020Co-Authors: Ramawatar Yadav, Vipan Kumar, Prashant JhaAbstract:Evolution of Kochia resistance to glyphosate and dicamba is a concern for growers in the US Great Plains. An increasing use of glyphosate and dicamba with the widespread adoption of glyphosate/dicamba-resistant (GDR) soybean in recent years may warrant greater attention. Long-term stewardship of this new stacked-trait technology will require the implementation of diverse weed control strategies, such as the use of soil-residual herbicides (PRE) aimed at effective control of GDR Kochia. Field experiments were conducted in Huntley, MT, in 2017 and 2018, and Hays, KS, in 2018 to determine the effectiveness of various PRE herbicides applied alone or followed by (fb) a POST treatment of glyphosate plus dicamba for controlling GDR Kochia in GDR soybean. Among PRE herbicides tested, sulfentrazone provided complete (100%), season-long control of GDR Kochia at both sites. In addition, PRE fb POST programs tested in this study brought 71% to 100% control of GDR Kochia throughout the season at both sites. Pyroxasulfone applied PRE resulted in 57% to 70% control across sites at 9 to 10 wk after PRE (WAPRE). However, mixing dicamba with pyroxasulfone improved control up to 25% at both sites. Kochia plants surviving pyroxasulfone applied PRE alone produced 2,530 seeds m–² compared with pyroxasulfone + dicamba (230 seeds m–²) at the Montana site. No differences in soybean grain yields were observed with PRE alone or PRE fb POST treatments at the Montana site; however, dicamba, pyroxasulfone, and pendimethalin + dimethenamid-P applied PRE brought lower grain yield (1,150 kg ha–¹) compared to all other tested programs at the Kansas site. In conclusion, effective PRE or PRE fb POST (two-pass) programs tested in this research should be proactively utilized by the growers to manage GDR Kochia in GDR soybean. Nomenclature: Glyphosate; dicamba; dimethenamid-P; pendimethalin; pyroxasulfone; sulfentrazone; Kochia, Bassia scoparia (L.) A.J. Scott; soybean, Glycine max (L.) Merr
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Dicamba-resistant Kochia (Bassia scoparia) in Kansas: characterization and management with fall- or spring-applied PRE herbicides
Weed Technology, 2019Co-Authors: Vipan Kumar, Phillip W. Stahlman, Prashant Jha, Randall S. Currie, Ryan P. Engel, Curtis R. ThompsonAbstract:Dicamba-resistant (DR) Kochia is an increasing concern for growers in the US Great Plains, including Kansas. Greenhouse and field experiments (Garden City and Tribune, KS, in the 2014 to 2015 growing season) were conducted to characterize the dicamba resistance levels in two recently evolved DR Kochia accessions collected from fallow fields (wheat–sorghum–fallow rotation) near Hays, KS, and to determine the effectiveness of various PRE herbicide tank mixtures applied in fall or spring prior to the fallow year. Dicamba dose–response studies indicated that the KS-110 and KS-113 accessions had 5- to 8-fold resistance to dicamba, respectively, relative to a dicamba-susceptible (DS) accession. In separate field studies, atrazine-based PRE herbicide tank mixtures, dicamba + pendimethalin + sulfentrazone, and metribuzin + sulfentrazone when applied in the spring had excellent Kochia control (85% to 95%) for 3 to 4 mo at the Garden City and Tribune sites. In contrast, Kochia control with those PRE herbicide tank mixtures when applied in the fall did not exceed 79% at the later evaluation dates. In conclusion, the tested Kochia accessions from western Kansas had evolved moderate to high levels of resistance to dicamba. Growers should utilize these effective PRE herbicide tank mixtures (multiple sites of action) in early spring to manage Kochia seed bank during the summer fallow phase of this 3-yr crop rotation (wheat–corn/sorghum–fallow) in the Central Great Plains.
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first report of Kochia bassia scoparia with cross resistance to dicamba and fluroxypyr in western kansas
Weed Technology, 2019Co-Authors: Vipan Kumar, Prashant Jha, Randall S. Currie, Phillip W. StahlmanAbstract:Evolution and rapid spread of herbicide-resistant (HR) Kochia has become a significant challenge for growers in the U.S. Great Plains. The main objectives of this research were to confirm and characterize the response of putative auxinic HR (Aux-HR) Kochia accessions (designated as KS-4A, KS-4D, KS-4H, KS-10A, KS-10-G, and KS-10H) collected from two different corn fields near Garden City, KS, to dicamba and fluroxypyr and to determine the EPSPS gene copy number to detect whether those accessions were also resistant to glyphosate. Single-dose experiments indicated that putative Aux-HR Kochia accessions had 78% to 100% and 85% to 100% survivors when treated with dicamba (560 g ae ha−1) and fluroxypyr (235 g ae ha−1), respectively. Whole-plant dicamba dose–response studies revealed that the selected Aux-HR accessions had 2.9- to 15.1- and 3.1- to 9.4-fold resistance to dicamba relative to two susceptible accessions (MT-SUS and KS-SUS). In a separate fluroxypyr dose–response experiment, the selected Aux-HR accessions also exhibited 3.8- to 7.3- and 3.0- to 8.6-fold resistance to fluroxypyr on the basis of shoot fresh and dry weight responses, respectively. The confirmed Aux-HR Kochia accessions also had 3 to 13 EPSPS gene copies relative to MT-SUS and KS-SUS accessions (each with 1 EPSPS gene copy). These results suggest that the putative Aux-HR Kochia accessions from Kansas had developed moderate to high levels of cross-resistance to dicamba and fluroxypyr and low to high levels of resistance to glyphosate. This is the first confirmation of Kochia accessions with cross-resistance to dicamba and fluroxypyr in Kansas. Growers should use diverse Kochia control programs, including the proper use of dicamba and fluroxypyr stewardship, use of cover crops, occasional tillage, diversified crop rotations, and alternative effective herbicides to prevent further evolution and spread of Aux-HR Kochia on their fields.
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First Report of Kochia (Bassia scoparia) with Cross-Resistance to Dicamba and Fluroxypyr in Western Kansas
Weed Technology, 2019Co-Authors: Vipan Kumar, Prashant Jha, Randall S. Currie, Phillip W. StahlmanAbstract:Evolution and rapid spread of herbicide-resistant (HR) Kochia has become a significant challenge for growers in the U.S. Great Plains. The main objectives of this research were to confirm and characterize the response of putative auxinic HR (Aux-HR) Kochia accessions (designated as KS-4A, KS-4D, KS-4H, KS-10A, KS-10-G, and KS-10H) collected from two different corn fields near Garden City, KS, to dicamba and fluroxypyr and to determine the EPSPS gene copy number to detect whether those accessions were also resistant to glyphosate. Single-dose experiments indicated that putative Aux-HR Kochia accessions had 78% to 100% and 85% to 100% survivors when treated with dicamba (560 g ae ha – ¹) and fluroxypyr (235 g ae ha–¹), respectively. Whole-plant dicamba dose–response studies revealed that the selected Aux-HR accessions had 2.9- to 15.1- and 3.1- to 9.4-fold resistance to dicamba relative to two susceptible accessions (MT-SUS and KS-SUS). In a separate fluroxypyr dose–response experiment, the selected Aux-HR accessions also exhibited 3.8- to 7.3- and 3.0- to 8.6-fold resistance to fluroxypyr on the basis of shoot fresh and dry weight responses, respectively. The confirmed Aux-HR Kochia accessions also had 3 to 13 EPSPS gene copies relative to MT-SUS and KS-SUS accessions (each with 1 EPSPS gene copy). These results suggest that the putative Aux-HR Kochia accessions from Kansas had developed moderate to high levels of cross-resistance to dicamba and fluroxypyr and low to high levels of resistance to glyphosate. This is the first confirmation of Kochia accessions with cross-resistance to dicamba and fluroxypyr in Kansas. Growers should use diverse Kochia control programs, including the proper use of dicamba and fluroxypyr stewardship, use of cover crops, occasional tillage, diversified crop rotations, and alternative effective herbicides to prevent further evolution and spread of Aux-HR Kochia on their fields. Nomenclature: Dicamba; fluroxypyr; glyphosate; Kochia, Bassia scoparia (L.) A. J. Scott
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Discrimination of herbicide-resistant Kochia with hyperspectral imaging
Journal of Applied Remote Sensing, 2018Co-Authors: Paul W. Nugent, Joseph A. Shaw, Bryan Scherrer, Andrew Donelick, Vipan KumarAbstract:A hyperspectral imager was used to differentiate herbicide-resistant versus herbicide-susceptible biotypes of the agronomic weed Kochia, in different crops in the field at the Southern Agricultural Research Center in Huntley, Montana. Controlled greenhouse experiments showed that enough information was captured by the imager to classify plants as either a crop, herbicide-susceptible or herbicide-resistant Kochia. The current analysis is developing an algorithm that will work in more uncontrolled outdoor situations. In overcast conditions, the algorithm correctly identified dicamba-resistant Kochia, glyphosate-resistant Kochia, and glyphosate- and dicamba-susceptible Kochia with 67%, 76%, and 80% success rates, respectively.
Prashant Jha - One of the best experts on this subject based on the ideXlab platform.
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herbicide programs to manage glyphosate dicamba resistant Kochia bassia scoparia in glyphosate dicamba resistant soybean
Weed Technology, 2020Co-Authors: Ramawatar Yadav, Vipan Kumar, Prashant JhaAbstract:Evolution of Kochia resistance to glyphosate and dicamba is a concern for growers in the US Great Plains. An increasing use of glyphosate and dicamba with the widespread adoption of glyphosate/dicamba-resistant (GDR) soybean in recent years may warrant greater attention. Long-term stewardship of this new stacked-trait technology will require the implementation of diverse weed control strategies, such as the use of soil-residual herbicides (PRE) aimed at effective control of GDR Kochia. Field experiments were conducted in Huntley, MT, in 2017 and 2018, and Hays, KS, in 2018 to determine the effectiveness of various PRE herbicides applied alone or followed by (fb) a POST treatment of glyphosate plus dicamba for controlling GDR Kochia in GDR soybean. Among PRE herbicides tested, sulfentrazone provided complete (100%), season-long control of GDR Kochia at both sites. In addition, PRE fb POST programs tested in this study brought 71% to 100% control of GDR Kochia throughout the season at both sites. Pyroxasulfone applied PRE resulted in 57% to 70% control across sites at 9 to 10 wk after PRE (WAPRE). However, mixing dicamba with pyroxasulfone improved control up to 25% at both sites. Kochia plants surviving pyroxasulfone applied PRE alone produced 2,530 seeds m–² compared with pyroxasulfone + dicamba (230 seeds m–²) at the Montana site. No differences in soybean grain yields were observed with PRE alone or PRE fb POST treatments at the Montana site; however, dicamba, pyroxasulfone, and pendimethalin + dimethenamid-P applied PRE brought lower grain yield (1,150 kg ha–¹) compared to all other tested programs at the Kansas site. In conclusion, effective PRE or PRE fb POST (two-pass) programs tested in this research should be proactively utilized by the growers to manage GDR Kochia in GDR soybean. Nomenclature: Glyphosate; dicamba; dimethenamid-P; pendimethalin; pyroxasulfone; sulfentrazone; Kochia, Bassia scoparia (L.) A.J. Scott; soybean, Glycine max (L.) Merr
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Dicamba-resistant Kochia (Bassia scoparia) in Kansas: characterization and management with fall- or spring-applied PRE herbicides
Weed Technology, 2019Co-Authors: Vipan Kumar, Phillip W. Stahlman, Prashant Jha, Randall S. Currie, Ryan P. Engel, Curtis R. ThompsonAbstract:Dicamba-resistant (DR) Kochia is an increasing concern for growers in the US Great Plains, including Kansas. Greenhouse and field experiments (Garden City and Tribune, KS, in the 2014 to 2015 growing season) were conducted to characterize the dicamba resistance levels in two recently evolved DR Kochia accessions collected from fallow fields (wheat–sorghum–fallow rotation) near Hays, KS, and to determine the effectiveness of various PRE herbicide tank mixtures applied in fall or spring prior to the fallow year. Dicamba dose–response studies indicated that the KS-110 and KS-113 accessions had 5- to 8-fold resistance to dicamba, respectively, relative to a dicamba-susceptible (DS) accession. In separate field studies, atrazine-based PRE herbicide tank mixtures, dicamba + pendimethalin + sulfentrazone, and metribuzin + sulfentrazone when applied in the spring had excellent Kochia control (85% to 95%) for 3 to 4 mo at the Garden City and Tribune sites. In contrast, Kochia control with those PRE herbicide tank mixtures when applied in the fall did not exceed 79% at the later evaluation dates. In conclusion, the tested Kochia accessions from western Kansas had evolved moderate to high levels of resistance to dicamba. Growers should utilize these effective PRE herbicide tank mixtures (multiple sites of action) in early spring to manage Kochia seed bank during the summer fallow phase of this 3-yr crop rotation (wheat–corn/sorghum–fallow) in the Central Great Plains.
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first report of Kochia bassia scoparia with cross resistance to dicamba and fluroxypyr in western kansas
Weed Technology, 2019Co-Authors: Vipan Kumar, Prashant Jha, Randall S. Currie, Phillip W. StahlmanAbstract:Evolution and rapid spread of herbicide-resistant (HR) Kochia has become a significant challenge for growers in the U.S. Great Plains. The main objectives of this research were to confirm and characterize the response of putative auxinic HR (Aux-HR) Kochia accessions (designated as KS-4A, KS-4D, KS-4H, KS-10A, KS-10-G, and KS-10H) collected from two different corn fields near Garden City, KS, to dicamba and fluroxypyr and to determine the EPSPS gene copy number to detect whether those accessions were also resistant to glyphosate. Single-dose experiments indicated that putative Aux-HR Kochia accessions had 78% to 100% and 85% to 100% survivors when treated with dicamba (560 g ae ha−1) and fluroxypyr (235 g ae ha−1), respectively. Whole-plant dicamba dose–response studies revealed that the selected Aux-HR accessions had 2.9- to 15.1- and 3.1- to 9.4-fold resistance to dicamba relative to two susceptible accessions (MT-SUS and KS-SUS). In a separate fluroxypyr dose–response experiment, the selected Aux-HR accessions also exhibited 3.8- to 7.3- and 3.0- to 8.6-fold resistance to fluroxypyr on the basis of shoot fresh and dry weight responses, respectively. The confirmed Aux-HR Kochia accessions also had 3 to 13 EPSPS gene copies relative to MT-SUS and KS-SUS accessions (each with 1 EPSPS gene copy). These results suggest that the putative Aux-HR Kochia accessions from Kansas had developed moderate to high levels of cross-resistance to dicamba and fluroxypyr and low to high levels of resistance to glyphosate. This is the first confirmation of Kochia accessions with cross-resistance to dicamba and fluroxypyr in Kansas. Growers should use diverse Kochia control programs, including the proper use of dicamba and fluroxypyr stewardship, use of cover crops, occasional tillage, diversified crop rotations, and alternative effective herbicides to prevent further evolution and spread of Aux-HR Kochia on their fields.
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First Report of Kochia (Bassia scoparia) with Cross-Resistance to Dicamba and Fluroxypyr in Western Kansas
Weed Technology, 2019Co-Authors: Vipan Kumar, Prashant Jha, Randall S. Currie, Phillip W. StahlmanAbstract:Evolution and rapid spread of herbicide-resistant (HR) Kochia has become a significant challenge for growers in the U.S. Great Plains. The main objectives of this research were to confirm and characterize the response of putative auxinic HR (Aux-HR) Kochia accessions (designated as KS-4A, KS-4D, KS-4H, KS-10A, KS-10-G, and KS-10H) collected from two different corn fields near Garden City, KS, to dicamba and fluroxypyr and to determine the EPSPS gene copy number to detect whether those accessions were also resistant to glyphosate. Single-dose experiments indicated that putative Aux-HR Kochia accessions had 78% to 100% and 85% to 100% survivors when treated with dicamba (560 g ae ha – ¹) and fluroxypyr (235 g ae ha–¹), respectively. Whole-plant dicamba dose–response studies revealed that the selected Aux-HR accessions had 2.9- to 15.1- and 3.1- to 9.4-fold resistance to dicamba relative to two susceptible accessions (MT-SUS and KS-SUS). In a separate fluroxypyr dose–response experiment, the selected Aux-HR accessions also exhibited 3.8- to 7.3- and 3.0- to 8.6-fold resistance to fluroxypyr on the basis of shoot fresh and dry weight responses, respectively. The confirmed Aux-HR Kochia accessions also had 3 to 13 EPSPS gene copies relative to MT-SUS and KS-SUS accessions (each with 1 EPSPS gene copy). These results suggest that the putative Aux-HR Kochia accessions from Kansas had developed moderate to high levels of cross-resistance to dicamba and fluroxypyr and low to high levels of resistance to glyphosate. This is the first confirmation of Kochia accessions with cross-resistance to dicamba and fluroxypyr in Kansas. Growers should use diverse Kochia control programs, including the proper use of dicamba and fluroxypyr stewardship, use of cover crops, occasional tillage, diversified crop rotations, and alternative effective herbicides to prevent further evolution and spread of Aux-HR Kochia on their fields. Nomenclature: Dicamba; fluroxypyr; glyphosate; Kochia, Bassia scoparia (L.) A. J. Scott
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confirmation of glyphosate resistant Kochia Kochia scoparia from sugar beet fields in idaho and oregon
Weed Technology, 2018Co-Authors: Vipan Kumar, Joel Felix, Don W Morishita, Prashant JhaAbstract:Glyphosate-resistant (GR) Kochia is an increasing management concern in major cropping systems of the northwestern US. In 2014, we investigated four putative GR Kochia accessions (designated as ALA, VAL, WIL, DB) collected from sugar beet fields in eastern Oregon and southwestern Idaho to characterize the level of evolved glyphosate resistance and determine the relationship between the 5-enol-pyruvylshikimate-3-phospate synthase (EPSPS) gene copy number and level of glyphosate resistance. The EPSPS gene copy number was used as a molecular marker to detect GR Kochia in subsequent surveys in 2015 and 2016. Based on LD50 values from a whole-plant dose-response study, the four putative GR Kochia populations were 2.0- to 9.6-fold more resistant to glyphosate than the glyphosate-susceptible (GS) accession. In an in vivo leafdisk shikimate assay, leaf disks of GS Kochia plants treated with 100-µM glyphosate accumulated 2.4- to 4.0-fold higher amounts of shikimate than the GR plants. The four GR accessions had 2.7 to 9.1 relative EPSPS gene copies compared with the GS accession (<1 EPSPS gene copies), and there was a linear relationship between EPSPS gene copy number and glyphosate resistance level (LD50 values). The 2015 and 2016 GR Kochia survey results indicated that about half of the collected populations from sugar beet fields in eastern Oregon had developed resistance to glyphosate whereas only one population from the Idaho collection was confirmed glyphosate resistant. This is the first confirmation of GR Kochia in sugar beet fields in eastern Oregon and southwestern Idaho. Diversified weed control programs will be required to prevent further development and spread of GR Kochia in sugar beet-based rotations in this region.Nomenclature: Glyphosate; Kochia, Kochia scoparia (L.) Schrad.; sugar beet, Beta vulgaris L.
Philip Westra - One of the best experts on this subject based on the ideXlab platform.
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The Draft Genome of Kochia scoparia and the Mechanism of Glyphosate Resistance via Transposon-Mediated EPSPS Tandem Gene Duplication
Genome biology and evolution, 2019Co-Authors: Eric L. Patterson, Philip Westra, Christopher A. Saski, Daniel B. Sloan, Patrick J. Tranel, Todd A. GainesAbstract:Increased copy number of the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene confers resistance to glyphosate, the world's most-used herbicide. There are typically three to eight EPSPS copies arranged in tandem in glyphosate-resistant populations of the weed Kochia (Kochia scoparia). Here, we report a draft genome assembly from a glyphosate-susceptible Kochia individual. Additionally, we assembled the EPSPS locus from a glyphosate-resistant Kochia plant by sequencing select bacterial artificial chromosomes from a Kochia bacterial artificial chromosome library. Comparing the resistant and susceptible EPSPS locus allowed us to reconstruct the history of duplication in the structurally complex EPSPS locus and uncover the genes that are coduplicated with EPSPS, several of which have a corresponding change in transcription. The comparison between the susceptible and resistant assemblies revealed two dominant repeat types. Additionally, we discovered a mobile genetic element with a FHY3/FAR1-like gene predicted in its sequence that is associated with the duplicated EPSPS gene copies in the resistant line. We present a hypothetical model based on unequal crossing over that implicates this mobile element as responsible for the origin of the EPSPS gene duplication event and the evolution of herbicide resistance in this system. These findings add to our understanding of stress resistance evolution and provide an example of rapid resistance evolution to high levels of environmental stress.
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Survey reveals frequency of multiple resistance to glyphosate and dicamba in Kochia (Bassia scoparia)
Weed Technology, 2019Co-Authors: Eric P. Westra, Scott J Nissen, Philip Westra, Thomas J. Getts, Todd A. GainesAbstract:Glyphosate-resistant (GR) Kochia has been reported across the western and midwestern United States. From 2011 to 2014, Kochia seed was collected from agronomic regions across Colorado to evaluate the frequency and distribution of glyphosate-, dicamba-, and fluroxypyr-resistant Kochia, and to assess the frequency of multiple resistance. Here we report resistance frequency as percent resistance within a population, and resistance distribution as the percentage and locations of accessions classified as resistant to a discriminating herbicide dose. In 2011, Kochia accessions were screened with glyphosate only, whereas from 2012 to 2014 Kochia accessions were screened with glyphosate, dicamba, and fluroxypyr. From 2011 to 2014, the percentages of GR Kochia accessions were 60%, 45%, 39%, and 52%, respectively. The percentages of dicamba-resistant Kochia accessions from 2012 to 2014 were 33%, 45%, and 28%, respectively. No fluroxypyr-resistant accessions were identified. Multiple-resistant accessions (low resistance or resistant to both glyphosate and dicamba) from 2012 to 2014 were identified in 14%, 15%, and 20% of total sampled accessions, respectively. This confirmation of multiple glyphosate and dicamba resistance in Kochia accessions emphasizes the importance of diversity in herbicide site of action as critical to extend the usefulness of remaining effective herbicides such as fluroxypyr for management of this weed.Nomenclature: Dicamba; fluroxypyr; glyphosate; Kochia, Bassia scoparia (L.) A.J. Scott
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The Draft Genome of Kochia scoparia and the Mechanism of Glyphosate Resistance via Transposon-Mediated EPSPS Tandem Gene Duplication
2019Co-Authors: Eric L. Patterson, Philip Westra, Christopher A. Saski, Daniel B. Sloan, Patrick J. Tranel, Todd A. GainesAbstract:ABSTRACT Increased copy number of the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene confers resistance to glyphosate, the world’s most-used herbicide. There are typically three to eight EPSPS copies arranged in tandem in glyphosate-resistant populations of the weed Kochia (Kochia scoparia). Here, we report a draft genome assembly from a glyphosate-susceptible Kochia individual. Additionally, we assembled the EPSPS locus from a glyphosate-resistant Kochia plant by sequencing a Kochia bacterial artificial chromosome library. These resources helped reconstruct the history of duplication in the structurally complex EPSPS locus and uncover the genes that are co-duplicated with EPSPS, several of which have a corresponding change in transcription. The comparison between the susceptible and resistant assemblies revealed two dominant repeat types. We discovered a FHY3/FAR1-like mobile genetic element that is associated with the duplicated EPSPS gene copies in the resistant line. We present a hypothetical model based on unequal crossing over that implicates this mobile element as responsible for the origin of the EPSPS gene duplication event and the evolution of herbicide resistance in this system. These findings add to our understanding of stress resistance evolution and provide an example of rapid resistance evolution to high levels of environmental stress.
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Kochia Kochia scoparia emergence profiles and seed persistence across the central great plains
Weed Science, 2017Co-Authors: Anita J Dille, Phillip W. Stahlman, Philip Westra, Randall S. Currie, Andrew R. Kniss, Gustavo M. Sbatella, Robert G. Wilson, Patrick W Geier, Jarrett D Riffel, Michael MoechnigAbstract:Timing of weed emergence and seed persistence in the soil influence the ability to implement timely and effective control practices. Emergence patterns and seed persistence of Kochia populations were monitored in 2010 and 2011 at sites in Kansas, Colorado, Wyoming, Nebraska, and South Dakota. Weekly observations of emergence were initiated in March and continued until no new emergence occurred. Seed was harvested from each site, placed into 100-seed mesh packets, and buried at depths of 0, 2.5, and 10 cm in fall of 2010 and 2011. Packets were exhumed at 6-mo intervals over 2 yr. Viability of exhumed seeds was evaluated. Nonlinear mixed-effects Weibull models were fit to cumulative emergence (%) across growing degree days (GDD) and to viable seed (%) across burial time to describe their fixed and random effects across site-years. Final emergence densities varied among site-years and ranged from as few as 4 to almost 380,000 seedlings m−2. Across 11 site-years in Kansas, cumulative GDD needed for 10% emergence were 168, while across 6 site-years in Wyoming and Nebraska, only 90 GDD were needed; on the calendar, this date shifted from early to late March. The majority (>95%) of Kochia seed did not persist for more than 2 yr. Remaining seed viability was generally >80% when seeds were exhumed within 6 mo after burial in March, and declined to <5% by October of the first year after burial. Burial did not appear to increase or decrease seed viability over time but placed seed in a position from which seedling emergence would not be possible. High seedling emergence that occurs very early in the spring emphasizes the need for fall or early spring PRE weed control such as tillage, herbicides, and cover crops, while continued emergence into midsummer emphasizes the need for extended periods of Kochia management.Nomenclature: Kochia, Kochia scoparia (L.) Schrad. KCHSC.
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molecular basis of evolved resistance to glyphosate and acetolactate synthase inhibitor herbicides in Kochia Kochia scoparia accessions from montana
Weed Science, 2015Co-Authors: Vipan Kumar, Prashant Jha, Eric P. Westra, Darci Giacomini, Philip WestraAbstract:Abstract The rapid evolution and spread of glyphosate-resistant (GR) Kochia in the Northern Great Plains is an increasing threat to GR cropping systems and conservation tillage practices common in this region. GR Kochia accessions with 4.6- to 11-fold levels of resistance to glyphosate have recently been reported in Montana. Those GR Kochia accessions were also suspected to be resistant to acetolactate synthase (ALS) inhibitors, i.e., multiple herbicide-resistant (MHR) Kochia. In this research, the level of resistance to the ALS-inhibitor herbicides (sulfonylureas) and the molecular mechanisms conferring resistance to glyphosate and ALS-inhibitor herbicides in MHR Kochia was investigated. On the basis of whole-plant dose–response assays, MHR Kochia accessions (GIL01, JOP01, and CHES01) were 9.3- to 30-fold more resistant to premixed thifensulfuron methyl + tribenuron methyl + metsulfuron methyl than the susceptible (SUS) accession. In an in vivo leaf-disk shikimate assay, MHR plants accumulated less shiki...
