Variable Tolerance among Palmer Amaranth (Amaranthus palmeri) Biotypes to Glyphosate, 2,4-D Amine, and Premix Formulation of Glyphosate plus 2,4-D Choline (Enlist Duo®) Herbicide

Weed Science ◽  
2017 ◽  
Vol 65 (6) ◽  
pp. 787-797 ◽  
Author(s):  
Douglas J. Spaunhorst ◽  
William G. Johnson
Keyword(s):  
Dose Response ◽  
Active Ingredient ◽  
Maximum Rate ◽  
Glyphosate Resistance ◽  
Palmer Amaranth ◽  
Amaranthus Palmeri ◽  
Whole Plant

Adoption of soybean that is resistant to 2,4-D will result in more use of glyphosate plus 2,4-D premixes and tank mixtures. Preliminary whole-plant greenhouse assays confirm most Palmer amaranth populations found in Indiana are glyphosate-resistant (GR), and some biotypes exhibit tolerance to 2,4-D amine. Dose–response experiments were conducted to determine the level of glyphosate resistance and 2,4-D amine tolerance in four Palmer amaranth biotypes. A premix formulation of glyphosate plus 2,4-D choline was also evaluated. The R1, R2, and R3 biotypes were 31- to 66-fold more resistant to glyphosate (R:S ratio) than the S1 biotype based on the herbicide dose to cause 90% mortality (LD90). The maximum POST rate of the premix formulation of Enlist Duo®labeled in ‘Enlist®’soybean is 2,195 g ae ha−1. When separated by active ingredient, the maximum POST rate of Enlist Duo®is equivalent to 1,141 and 1,054 g ae ha−1of glyphosate and 2,4-D choline, respectively. In the absence of glyphosate, the maximum rate of 2,4-D (1,054 g ae ha−1) in the premix formulation of Enlist Duo®controlled S1, R2, and R3 biotypes, but failed to control all plants from the R1 biotype. Estimates for LD90showed the R1 biotype was 3-fold more tolerant than the S1 biotype to 2,4-D amine. However, no plants survived the 1,155 g ae ha−1(600 g ae ha−1of glyphosate plus 555 g ae ha−12,4-D) treatment with the premix formulation of glyphosate plus 2,4-D choline. Overall, results from this experiment suggest GR Palmer amaranth that also exhibits increased tolerance to 2,4-D amine will be difficult to control with glyphosate or 2,4-D alone, but can be controlled POST with Enlist Duo®at lower than labeled field rates (1,618 to 2,195 g ae ha−1).

scholarly journals Inheritance of Evolved Glyphosate Resistance in a North Carolina Palmer Amaranth (Amaranthus palmeri) Biotype

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Aman Chandi ◽  
Susana R. Milla-Lewis ◽  
Darci Giacomini ◽  
Philip Westra ◽  
Christopher Preston ◽  
...  
Keyword(s):  
North Carolina ◽  
Dose Response ◽  
Genome Analysis ◽  
Copy Number ◽  
Single Gene ◽  
Nuclear Genome ◽  
Glyphosate Resistance ◽  
Palmer Amaranth ◽  
Amaranthus Palmeri ◽  
Dose Responses

Inheritance of glyphosate resistance in a Palmer amaranth biotype from North Carolina was studied. Glyphosate rates for 50% survival of glyphosate-resistant (GR) and glyphosate-susceptible (GS) biotypes were 1288 and 58 g ha−1, respectively. These values for F1 progenies obtained from reciprocal crosses (GR×GSandGS×GRwere 794 and 501 g ha−1, respectively. Dose response of F1 progenies indicated that resistance was not fully dominant over susceptibility. Lack of significant differences between dose responses for reciprocal F1 families suggested that genetic control of glyphosate resistance was governed by nuclear genome. Analysis of F1 backcross (BC1F1) families showed that 10 and 8 BC1F1 families out of 15 fitted monogenic inheritance at 2000 and 3000 g ha−1glyphosate, respectively. These results indicate that inheritance of glyphosate resistance in this biotype is incompletely dominant, nuclear inherited, and might not be consistent with a single gene mechanism of inheritance. Relative 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) copy number varied from 22 to 63 across 10 individuals from resistant biotype. This suggested that variableEPSPScopy number in the parents might be influential in determining if inheritance of glyphosate resistance is monogenic or polygenic in this biotype.

Differential Response of Arkansas Palmer Amaranth (Amaranthus palmeri) to Glyphosate and Mesotrione

2018 ◽  
Vol 32 (5) ◽  
pp. 579-585 ◽  
Author(s):  
Shilpa Singh ◽  
Nilda Roma-Burgos ◽  
Vijay Singh ◽  
Ed Allan L. Alcober ◽  
Reiofeli Salas-Perez ◽  
...  
Keyword(s):  
Dose Response ◽  
Differential Response ◽  
Palmer Amaranth ◽  
Amaranthus Palmeri ◽  
Susceptible Population ◽  
Tolerance Level ◽  
Crop Fields ◽  
Greenhouse Study ◽  
Effective Doses

AbstractWe conducted a greenhouse study to evaluate the differential response of Palmer amaranth to glyphosate and mesotrione and to quantify the level of tolerance to mesotrione in recalcitrant (difficult-to-control) accessions and their offspring. Seeds were collected from 174 crop fields (corn, cotton, and soybean) across Arkansas between 2008 and 2016. Palmer amaranth seedlings (7 to 10 cm tall) were treated with glyphosate at 840 g ae ha–1or mesotrione at 105 g ha–1. Overall, 47% of the accessions (172) were resistant to glyphosate with 68% survivors. Almost 35% of accessions were highly resistant, with 90% survivors. The majority of survivors from glyphosate application incurred between 31% and 60% injury. Mesotrione killed 66% of the accessions (174); the remaining accessions had survivors with injury ranging from 61% to 90%. Accessions with the least response to mesotrione were selected to determine tolerance level. Dose–response assays were conducted with four recalcitrant populations and their F1progeny. The average effective doses (ED50) for the parent accessions and F1progeny of survivors were 21.5 g ha–1and 27.5 g ha–1, respectively. The recalcitrant parent populations were three- to five-fold more tolerant to mesotrione than the known susceptible population, as were the F1progeny.

Susceptibility of Palmer amaranth (Amaranthus palmeri) to herbicides in accessions collected from the North Carolina Coastal Plain

Weed Science ◽  
2020 ◽  
Vol 68 (6) ◽  
pp. 582-593
Author(s):  
Denis J. Mahoney ◽  
David L. Jordan ◽  
Nilda Roma-Burgos ◽  
Katherine M. Jennings ◽  
Ramon G. Leon ◽  
...  
Keyword(s):  
North Carolina ◽  
Dose Response ◽  
Coastal Plain ◽  
Weed Management ◽  
Acetolactate Synthase ◽  
Fold Increase ◽  
Palmer Amaranth ◽  
Amaranthus Palmeri ◽  
Sites Of Action ◽  
Two Populations

AbstractPalmer amaranth (Amaranthus palmeri S. Watson) populations resistant to acetolactate synthase (ALS)-inhibiting herbicides and glyphosate are fairly common throughout the state of North Carolina (NC). This has led farm managers to rely more heavily on herbicides with other sites of action (SOA) for A. palmeri control, especially protoporphyrinogen oxidase and glutamine synthetase inhibitors. In the fall of 2016, seeds from A. palmeri populations were collected from the NC Coastal Plain, the state’s most prominent agricultural region. In separate experiments, plants with 2 to 4 leaves from the 110 populations were treated with field use rates of glyphosate, glufosinate-ammonium, fomesafen, mesotrione, or thifensulfuron-methyl. Percent visible control and survival were evaluated 3 wk after treatment. Survival frequencies were highest following glyphosate (99%) or thifensulfuron-methyl (96%) treatment. Known mutations conferring resistance to ALS inhibitors were found in populations surviving thifensulfuron-methyl application (Ala-122-Ser, Pro-197-Ser, Trp-574-Leu, and/or Ser-653-Asn), in addition to a new mutation (Ala-282-Asp) that requires further investigation. Forty-two populations had survivors after mesotrione application, with one population having 17% survival. Four populations survived fomesafen treatment, while none survived glufosinate. Dose–response studies showed an increase in fomesafen needed to kill 50% of two populations (LD50); however, these rates were far below the field use rate (less than 5 g ha−1). In two populations following mesotrione dose–response studies, a 2.4- to 3.3-fold increase was noted, with LD90 values approaching the field use rate (72.8 and 89.8 g ha−1). Screening of the progeny of individuals surviving mesotrione confirmed the presence of resistance alleles, as there were a higher number of survivors at the 1X rate compared with the parent population, confirming resistance to mesotrione. These data suggest A. palmeri resistant to chemistries other than glyphosate and thifensulfuron-methyl are present in NC, which highlights the need for weed management approaches to mitigate the evolution and spread of herbicide-resistant populations.

scholarly journals Confirmation of S-metolachlor resistance in Palmer amaranth (Amaranthus palmeri)

2019 ◽  
Vol 33 (5) ◽  
pp. 720-726 ◽  
Author(s):  
Chad Brabham ◽  
Jason K. Norsworthy ◽  
Michael M. Houston ◽  
Vijay K Varanasi ◽  
Tom Barber
Keyword(s):  
Dose Response ◽  
Resistance Mechanism ◽  
Acetolactate Synthase ◽  
Chain Fatty Acid ◽  
Palmer Amaranth ◽  
Cross Resistance ◽  
Amaranthus Palmeri ◽  
Glutathione S Transferase ◽  
Long Chain Fatty Acid ◽  
Long Chain

AbstractS-Metolachlor is commonly used by soybean and cotton growers, especially with POST treatments for overlapping residuals, to obtain season-long control of glyphosate- and acetolactate synthase (ALS)–resistant Palmer amaranth. In Crittenden County, AR, reports of Palmer amaranth escapes following S-metolachlor treatment were first noted at field sites near Crawfordsville and Marion in 2016. Field and greenhouse experiments were conducted to confirm S-metolachlor resistance and to test for cross-resistance to other very-long-chain fatty acid (VLCFA)–inhibiting herbicides in Palmer amaranth accessions from Crawfordsville and Marion. Palmer amaranth control in the field (soil <3% organic matter) 14 d after treatment (DAT) was ≥94% with a 1× rate of acetochlor (1,472 g ai ha–1; emulsifiable concentrate formulation) and dimethenamid-P (631 g ai ha–1). However, S-metolachlor at 1,064 g ai ha–1 provided only 76% control, which was not significantly different from the 1/2× and 1/4× rates of dimethenamid-P and acetochlor (66% to 85%). In the greenhouse, Palmer amaranth accessions from Marion and Crawfordsville were 9.8 and 8.3 times more resistant to S-metolachlor compared with two susceptible accessions based on LD50 values obtained from dose–response experiments. Two-thirds and 1.5 times S-metolachlor at 1,064 g ha–1 were the estimated rates required to obtain 90% mortality of the Crawfordsville and Marion accessions, respectively. Data collected from the field and greenhouse confirm that these accessions have evolved a low level of resistance to S-metolachlor. In an agar-based assay, the level of resistance in the Marion accession was significantly reduced in the presence of a glutathione S-transferase (GST) inhibitor, suggesting that GSTs are the probable resistance mechanism. With respect to other VLCFA-inhibiting herbicides, Marion and Crawfordsville accessions were not cross-resistant to acetochlor, dimethenamid-P, or pyroxasulfone. However, both accessions, based on LD50 values obtained from greenhouse dose–response experiments, exhibited reduced sensitivity (1.5- to 3.6-fold) to the tested VLCFA-inhibiting herbicides.

scholarly journals Interference of Selected Palmer Amaranth (Amaranthus palmeri) Biotypes in Soybean (Glycine max)

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Aman Chandi ◽  
David L. Jordan ◽  
Alan C. York ◽  
Susana R. Milla-Lewis ◽  
James D. Burton ◽  
...  
Keyword(s):  
Glycine Max ◽  
Acetolactate Synthase ◽  
Dry Weight ◽  
Glyphosate Resistance ◽  
Palmer Amaranth ◽  
Amaranthus Palmeri ◽  
Fresh Weight ◽  
Row Crops ◽  
Soybean Yield ◽  
Competitive Disadvantage

Palmer amaranth (Amaranthus palmeriS. Wats.) has become difficult to control in row crops due to selection for biotypes that are no longer controlled by acetolactate synthase inhibiting herbicides and/or glyphosate. Early season interference in soybean [Glycine max(L.) Merr.] for 40 days after emergence by three glyphosate-resistant (GR) and three glyphosate-susceptible (GS) Palmer amaranth biotypes from Georgia and North Carolina was compared in the greenhouse. A field experiment over 2 years compared season-long interference of these biotypes in soybean. The six Palmer amaranth biotypes reduced soybean height similarly in the greenhouse but did not affect soybean height in the field. Reduction in soybean fresh weight and dry weight in the greenhouse; and soybean yield in the field varied by Palmer amaranth biotypes. Soybean yield was reduced 21% by Palmer amaranth at the established field density of 0.37 plant m−2. When Palmer amaranth biotypes were grouped by response to glyphosate, the GS group reduced fresh weight, dry weight, and yield of soybean more than the GR group. The results indicate a possible small competitive disadvantage associated with glyphosate resistance, but observed differences among biotypes might also be associated with characteristics within and among biotypes other than glyphosate resistance.

Glyphosate-Resistant Palmer Amaranth (Amaranthus palmeri) Increases Herbicide Use, Tillage, and Hand-Weeding in Georgia Cotton

Weed Science ◽  
2014 ◽  
Vol 62 (2) ◽  
pp. 393-402 ◽  
Author(s):  
Lynn M. Sosnoskie ◽  
A. Stanley Culpepper
Keyword(s):  
Weed Management ◽  
Glyphosate Resistance ◽  
Palmer Amaranth ◽  
Extension Agents ◽  
Amaranthus Palmeri ◽  
Field Site ◽  
Timely Manner ◽  
Biological Attributes ◽  
Hand Weeding ◽  
Herbicide Use

In 2005, the existence of glyphosate-resistance in Palmer amaranth was confirmed at a single 250 ha field site in Macon County, Georgia. Currently, all cotton producing counties in Georgia are infested, to some degree, with glyphosate-resistant Palmer amaranth. In 2010 and 2011, surveys were administered to Georgia growers and extension agents to determine how the development of glyphosate-resistance has affected weed management in cotton. According to respondents, the numbers of cotton acres that were treated with paraquat, glufosinate and residual herbicides effective against Palmer amaranth more than doubled between 2000 to 2005 and 2006 to 2010. Glyphosate use declined between 2000 to 2005 and 2006 to 2010 although, on average, the active ingredient was still applied to a majority of cotton acres. Although grower herbicide input costs have more than doubled following the evolution and spread of glyphosate resistance, chemically-based control of Palmer amaranth is still not adequate. As a consequence, Georgia cotton growers hand weeded 52% of the crop at an average cost of $57 per hand-weeded ha; this represents a cost increase of at least 475% as compared to the years prior to resistance. In addition to increased herbicide use and hand weeding, growers in Georgia are also using mechanical, in-crop cultivation (44% of acres), tillage for the incorporation of preplant herbicides (20% of the acres), and post-harvest deep-turning (19% of the acres every three years) for weed control. Current weed management systems are more diverse, complex and expensive than those employed only a decade ago, but are effective at controlling glyphosate-resistant Palmer amaranth in glyphosate-resistant cotton. The success of these programs may be related to producers improved knowledge about herbicide resistance, and the biological attributes that make Palmer amaranth so challenging, as well as their ability to implement their management programs in a timely manner.

Palmer Amaranth (Amaranthus palmeri) in Tennessee Has Low Level Glyphosate Resistance

2008 ◽  
Vol 22 (1) ◽  
pp. 119-123 ◽  
Author(s):  
Lawrence E. Steckel ◽  
Christopher L. Main ◽  
Andrew T. Ellis ◽  
Thomas C. Mueller
Keyword(s):  
Glyphosate Resistance ◽  
Palmer Amaranth ◽  
Amaranthus Palmeri ◽  
Low Level

scholarly journals Distribution of Glyphosate- and Thifensulfuron-Resistant Palmer Amaranth (Amaranthus palmeri) in North Carolina

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Amy H. Poirier ◽  
Alan C. York ◽  
David L. Jordan ◽  
Aman Chandi ◽  
Wesley J. Everman ◽  
...  
Keyword(s):  
North Carolina ◽  
Crop Production ◽  
Error Variance ◽  
Glyphosate Resistance ◽  
Palmer Amaranth ◽  
Multiple Resistance ◽  
Amaranthus Palmeri ◽  
Row Crop ◽  
Resistance Trait ◽  
Als Inhibitor

Glyphosate resistance in Palmer amaranth was first confirmed in North Carolina in 2005. A survey that year indicated 17 and 18% of 290 populations sampled were resistant to glyphosate and thifensulfuron, respectively. During the fall of 2010, 274 predetermined sites in North Carolina were surveyed to determine distribution of Palmer amaranth and to determine if and where resistance to fomesafen, glufosinate, glyphosate, and thifensulfuron occurred. Palmer amaranth was present at 134 sites. When mortality for each biotype was compared to a known susceptible biotype for each herbicide within a rate, 93 and 36% of biotypes were controlled less by glyphosate (840 g ae ha−1) and thifensulfuron (70 g ai ha−1), respectively. This approach may have underestimated resistance for segregating populations due to lack of homogeneity of the herbicide resistance trait and its contribution to error variance. When mortality and visible control were combined, 98% and 97% of the populations were resistant to glyphosate and the ALS inhibitor thifensulfuron, respectively, and 95% of the populations expressed multiple resistance to both herbicides. This study confirms that Palmer amaranth is commonly found across the major row crop production regions of North Carolina and that resistance to glyphosate and ALS-inhibiting herbicides is nearly universal. No resistance to fomesafen or glufosinate was observed.

scholarly journals Influence of Soybean (Glycine max) Population and Herbicide Program on Palmer Amaranth (Amaranthus palmeri) Control, Soybean Yield, and Economic Return

ISRN Agronomy ◽  
2012 ◽  
Vol 2012 ◽  
pp. 1-8
Author(s):  
Amy E. Hoffner ◽  
David L. Jordan ◽  
Alan C. York ◽  
E. James Dunphy ◽  
Wesley J. Everman
Keyword(s):  
North Carolina ◽  
Glycine Max ◽  
Glyphosate Resistance ◽  
Palmer Amaranth ◽  
Production Costs ◽  
Soybean Plant ◽  
Amaranthus Palmeri ◽  
Economic Return ◽  
Soybean Yield ◽  
Herbicide Resistant

Palmer amaranth (Amaranthus palmeri S. Wats) has become one of the most prominent and difficult weeds to control in soybean (Glycine max (L.) Merr.) in North Carolina. A survey was conducted in North Carolina during fall 2010 to estimate the magnitude of this problem. Palmer amaranth was present in 39% of 2,512 fields representing 0.24% of soybean ha in North Carolina. In recent years, growers have reduced soybean seeding rates in an effort to decrease production costs associated with technology fees. However, given the increase in prevalence of Palmer amaranth and the difficultly in controlling this weed due to herbicide resistance, growers may need to reconsider reductions in seeding rates. Therefore, research was conducted during 2010 and 2011 to determine if Palmer amaranth control, soybean yield, and economic return were affected by soybean plant population, preemergence (PRE) and postemergence (POST) herbicides, and herbicide resistant traits (glufosinate-resistant and glyphosate-resistant cultivars). Applying PRE or POST herbicides and increasing soybean population increased Palmer amaranth control, soybean yield, and economic return when compared with POST herbicides only or when lower soybean populations were present. Efficacy of glufosinate and glyphosate did not vary in most instances, most likely because these herbicides were applied timely, and the frequency of glyphosate resistance did not exceed 10% in these fields.

scholarly journals Glyphosate-Resistant Palmer Amaranth (Amaranthus palmeri) in Nebraska: Confirmation, EPSPS Gene Amplification, and Response to POST Corn and Soybean Herbicides

2017 ◽  
Vol 31 (1) ◽  
pp. 80-93 ◽  
Author(s):  
Parminder S. Chahal ◽  
Vijay K. Varanasi ◽  
Mithila Jugulam ◽  
Amit J. Jhala
Keyword(s):  
Gene Amplification ◽  
Crop Production ◽  
Acetolactate Synthase ◽  
The United States ◽  
Palmer Amaranth ◽  
Amaranthus Palmeri ◽  
Epsps Gene ◽  
South Central ◽  
Whole Plant ◽  
Herbicide Programs

Palmer amaranth is the most problematic weed in agronomic crop production fields in the United States. A Palmer amaranth biotype was not controlled with sequential applications of glyphosate in glyphosate-resistant (GR) soybean production field in south-central Nebraska. The seeds of the putative GR Palmer amaranth biotype were collected in the fall of 2015. The objectives of this study were to (1) confirm GR Palmer amaranth and determine the level of resistance in a whole-plant dose-response bioassay, (2) determine the copy number of 5-enolpyruvylshikimate-3-phosphate (EPSPS) gene, the molecular target of glyphosate, and (3) evaluate the response of GR Palmer amaranth biotype to POST corn and soybean herbicides with different modes-of-action. Based on the effective dose required to control 90% of plants (ED90), the putative GR Palmer amaranth biotype was 37- to 40-fold resistant to glyphosate depending on the glyphosate-susceptible (GS) used as a baseline population.EPSPSgene amplification was present in the GR Palmer amaranth biotype with up to 32 to 105 EPSPS copies compared to the known GS biotypes. Response of GR Palmer amaranth to POST corn and soybean herbicides suggest reduced sensitivity to atrazine, hydroxyphenylpyruvate dioxygenase (HPPD)- (mesotrione, tembotrione, and topramezone), acetolactate synthase (ALS)- (halosulfuron-methyl), and protoporphyrinogen oxidase (PPO)- (carfentrazone and lactofen) inhibitors. GR Palmer amaranth was effectively controlled (>90%) with glufosinate applied at 593 g ai ha−1with ≥95% reduction in biomass. More research is needed to determine whether this biotype exhibits multiple resistant to other group of herbicides and evaluate herbicide programs for effective management in corn and soybean.

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