Response of Palmer Amaranth (Amaranthus palmeri) Accessions to Glyphosate, Fomesafen, and Pyrithiobac

2006 ◽  
Vol 20 (4) ◽  
pp. 885-892 ◽  
Author(s):  
Jason A. Bond ◽  
Lawrence R. Oliver ◽  
Daniel O. Stephenson
Keyword(s):  
United States ◽  
Dry Weight ◽  
Field Studies ◽  
Palmer Amaranth ◽  
Southern United States ◽  
Amaranthus Palmeri ◽  
Modes Of Action

Field studies were conducted at Fayetteville, Arkansas, to determine whether 47 Palmer amaranth accessions from different areas of the southern United States varied in response to postemergence applications of the registered rates of the isopropylamine salt of glyphosate (840 g ae/ha), fomesafen (420 g ai/ha), and pyrithiobac (70 g ai/ha). Glyphosate controlled all Palmer amaranth accessions at least 99% 21 d after treatment (DAT). Palmer amaranth control with fomesafen was equivalent for all accessions and at least 96% 21 DAT. Percent dry weight reductions were at least 92 and 94% for glyphosate and fomesafen, respectively. Palmer amaranth control with pyrithiobac was variable and ranged from 20 to 94% 21 DAT, but differences could not be attributed to accession origin. Herbicides with alternate modes of action from pyrithiobac should be utilized for Palmer amaranth control in regions where pyrithiobac has been used continuously.

Evaluation of 2,4-D–based Herbicide Mixtures for Control of Glyphosate-Resistant Palmer Amaranth (Amaranthus palmeri)

2018 ◽  
Vol 33 (2) ◽  
pp. 263-271 ◽  
Author(s):  
Benjamin H. Lawrence ◽  
Jason A. Bond ◽  
Thomas W. Eubank ◽  
Bobby R. Golden ◽  
Donald R. Cook ◽  
...  
Keyword(s):  
Dry Weight ◽  
Field Studies ◽  
Palmer Amaranth ◽  
Amaranthus Palmeri ◽  
Greenhouse Study ◽  
Synthetic Auxins ◽  
Control Options ◽  
Herbicide Mixture ◽  
Herbicide Mixtures ◽  
Sites Of Action

AbstractUnderstanding control of glyphosate-resistant (GR) Palmer amaranth with multiple herbicide sites of action, including synthetic auxins, is crucial for growers to minimize GR Palmer amaranth interference with crops. Field studies in 2013 and 2014 and a greenhouse study in 2014 were conducted in Stoneville, MS, to evaluate POST control of GR Palmer amaranth with 2,4-D alone and in mixtures with glyphosate and/or glufosinate. In the greenhouse study, control of 5- and 10-cm GR Palmer amaranth was 87% with 2,4-D at 0.84 kg ae ha−1. Dry weight reduction of GR Palmer amaranth was ≥81% with 2,4-D at 0.84 kg ha−1. In field studies, mixtures of glufosinate at 0.59 kg ai ha−1and 2,4-D at 0.56 or 1.12 kg ae ha−1controlled 5- to 10-cm GR Palmer amaranth 87% at 28 d after treatment (DAT). Averaged across glyphosate treatments, glufosinate applied alone applied to 5- to 10-cm GR Palmer amaranth reduced dry weight at 28 DAT to 20 g m−2from 82 g m−2and was comparable with that following 2,4-D applied alone at 1.12 kg ae ha−1and mixtures of glufosinate plus 2,4-D at 0.56 and 1.12 kg ae ha−1. Mixtures of 2,4-D plus glufosinate provided ≥92% control of 15- to 20-cm GR Palmer amaranth at 28 DAT. When applied to 15- to 20-cm plants, mixtures of 2,4-D plus glufosinate reduced GR Palmer amaranth density to ≤5 plants m−2compared with 65 plants m−2where no 2,4-D or glufosinate was applied. Glufosinate and 2,4-D are viable control options for 5- to 10-cm or 15- to 20-cm GR Palmer amaranth. However, 2,4-D did not improve GR Palmer amaranth control when added to any herbicide mixture except glyphosate and glufosinate applied to 15- to 20-cm plants at the 28 DAT evaluation.

Effect of bicyclopyrone herbicide on sweetpotato and Palmer amaranth (Amaranthus palmeri)

2020 ◽  
Vol 34 (4) ◽  
pp. 552-559
Author(s):  
Jennifer J. Lindley ◽  
Katherine M. Jennings ◽  
David W. Monks ◽  
Sushila Chaudhari ◽  
Jonathan R. Schultheis ◽  
...  
Keyword(s):  
Dry Weight ◽  
Field Studies ◽  
Palmer Amaranth ◽  
Yield Reduction ◽  
Amaranthus Palmeri ◽  
Marketable Yield ◽  
Management Options ◽  
Application Timing ◽  
Shoot Dry Weight ◽  
Plant Injury

AbstractManagement options are needed to limit sweetpotato yield loss due to weeds. Greenhouse studies were conducted in 2018 in Greensboro, NC, and in the field from 2016 to 2018 in Clinton, NC, to evaluate the effect of bicyclopyrone on sweetpotato and Palmer amaranth (field only). In greenhouse studies, Covington and NC04-531 clones were treated with bicyclopyrone (0, 25, 50, 100, or 150 g ai ha−1) either preplant (PP; i.e., immediately before transplanting) or post-transplant (PT; i.e., on the same day after transplanting). Sweetpotato plant injury and stunting increased, and vine length and shoot dry weight decreased with increasing rate of bicyclopyrone regardless of clone or application timing. In field studies, Beauregard (2016) or Covington (2017 and 2018) sweetpotato clones were treated with bicyclopyrone at 50 g ha−1 PP, flumioxazin at 107 g ai ha−1 PP, bicyclopyrone at 50 or 100 g ha−1 PP followed by (fb) S-metolachlor at 800 g ai ha−1 PT, flumioxazin at 107 g ha−1 PP fb S-metolachlor at 800 g ha−1 PT, flumioxazin at 107 g ha−1 PP fb S-metolachlor at 800 g ha−1 PT fb bicyclopyrone at 50 g ha−1 PT-directed, and clomazone at 420 g ai ha−1 PP fb S-metolachlor at 800 g ha−1 PT. Bicyclopyrone PP at 100 g ha−1 fb S-metolachlor PT caused 33% or greater crop stunting and 44% or greater marketable yield reduction compared with the weed-free check in 2016 (Beauregard) and 2017 (Covington). Bicyclopyrone PP at 50 g ha−1 alone or fb S-metolachlor PT resulted in 12% or less injury and similar no. 1 and jumbo yields as the weed-free check in 2 of 3 yr. Injury to Covington from bicyclopyrone PT-directed was 4% or less at 4 or 5 wk after transplanting and marketable yield was similar to that of the weed-free check in 2017 and 2018.

Safety and efficacy of linuron with or without an adjuvant or S-metolachlor for POST control of Palmer amaranth (Amaranthus palmeri) in sweetpotato

2021 ◽  
pp. 1-18
Author(s):  
Levi D. Moore ◽  
Katherine M. Jennings ◽  
David W. Monks ◽  
Ramon G. Leon ◽  
David L. Jordan ◽  
...  
Keyword(s):  
Nonionic Surfactant ◽  
Weed Control ◽  
Critical Period ◽  
Total Yield ◽  
Field Studies ◽  
Palmer Amaranth ◽  
Amaranthus Palmeri ◽  
Foliar Injury ◽  
Protoporphyrinogen Oxidase ◽  
Safety And Efficacy

Abstract Field studies were conducted to evaluate linuron for POST control of Palmer amaranth in sweetpotato to minimize reliance on protoporphyrinogen oxidase (PPO)-inhibiting herbicides. Treatments were arranged in a two by four factorial where the first factor consisted of two rates of linuron (420 and 700 g ai ha−1), and the second factor consisted of linuron applied alone or in combinations of linuron plus a nonionic surfactant (NIS) (0.5% v/v), linuron plus S-metolachlor (800 g ai ha−1), or linuron plus NIS plus S-metolachlor. In addition, S-metolachlor alone and nontreated weedy and weed-free checks were included for comparison. Treatments were applied to ‘Covington’ sweetpotato 8 d after transplanting (DAP). S-metolachlor alone provided poor Palmer amaranth control because emergence had occurred at applications. All treatments that included linuron resulted in at least 98 and 91% Palmer amaranth control 1 and 2 wk after treatment (WAT), respectively. Including NIS with linuron did not increase Palmer amaranth control compared to linuron alone, but increased sweetpotato injury and subsequently decreased total sweetpotato yield by 25%. Including S-metolachlor with linuron resulted in the greatest Palmer amaranth control 4 WAT, but increased crop foliar injury to 36% 1 WAT compared to 17% foliar injury from linuron alone. Marketable and total sweetpotato yield was similar between linuron alone and linuron plus S-metolachlor or S-metolachlor plus NIS treatments, though all treatments resulted in at least 39% less total yield than the weed-free check resulting from herbicide injury and/or Palmer amaranth competition. Because of the excellent POST Palmer amaranth control from linuron 1 WAT, a system including linuron applied 7 DAP followed by S-metolachlor applied 14 DAP could help to extend residual Palmer amaranth control further into the critical period of weed control while minimizing sweetpotato injury.

Critical Period for Palmer Amaranth (Amaranthus palmeri) Control in Pickling Cucumber

2018 ◽  
Vol 32 (5) ◽  
pp. 586-591
Author(s):  
Samuel J. McGowen ◽  
Katherine M. Jennings ◽  
Sushila Chaudhari ◽  
David W. Monks ◽  
Jonathan R. Schultheis ◽  
...  
Keyword(s):  
North Carolina ◽  
Critical Period ◽  
Relative Yield ◽  
Field Studies ◽  
Palmer Amaranth ◽  
Amaranthus Palmeri ◽  
Marketable Yield ◽  
Yield Data ◽  
Pickling Cucumber ◽  
Cucumber Yield

AbstractField studies were conducted in North Carolina to determine the critical period for Palmer amaranth control (CPPAC) in pickling cucumber. In removal treatments (REM), emerged Palmer amaranth were allowed to compete with cucumber for 14, 21, 28, or 35 d after sowing (DAS) in 2014 and 14, 21, 35, or 42 DAS in 2015, and cucumber was kept weed-free for the remainder of the season. In the establishment treatments (EST), cucumber was maintained free of Palmer amaranth by hand removal until 14, 21, 28, or 35 DAS in 2014 and until 14, 21, 35, or 42 DAS in 2015; after this, Palmer amaranth was allowed to establish and compete with the cucumber for the remainder of the season. The beginning and end of the CPPAC, based on 5% loss of marketable yield, was determined by fitting log-logistic and Gompertz equations to the relative yield data representing REM and EST, respectively. Season-long competition by Palmer amaranth reduced pickling cucumber yield by 45% to 98% and 88% to 98% during 2014 and 2015, respectively. When cucumber was planted on April 25, 2015, the CPPAC ranged from 570 to 1,002 heat units (HU), which corresponded to 32 to 49 DAS. However, when cucumber planting was delayed 2 to 4 wk (May 7 and May 21, 2014 and May 4, 2015), the CPPAC lasted from 100 to 918 HU (7 to 44 DAS). This research suggested that planting pickling cucumber as early as possible during the season may help to reduce competition by Palmer amaranth and delay the beginning of the CPPAC.

Evaluation of Herbicide Options for Alligatorweed (Alternanthera philoxeroides) Control in Rice

2015 ◽  
Vol 29 (4) ◽  
pp. 793-799 ◽  
Author(s):  
Samuel D. Willingham ◽  
Muthukumar V. Bagavathiannan ◽  
Katherine S. Carson ◽  
Todd J. Cogdill ◽  
Garry N. McCauley ◽  
...  
Keyword(s):  
United States ◽  
Weed Control ◽  
Field Studies ◽  
Rice Production ◽  
Alternanthera Philoxeroides ◽  
Southern United States ◽  
Rice Grain ◽  
Effective Management ◽  
Invasive Weed ◽  
Antagonistic Interactions

Alligatorweed is a perennial, invasive weed in southern United States rice production, but knowledge on effective management of this weed is limited, especially in conventional (non-imidazolinone-resistant) rice fields. Field studies were conducted in multiple environments in southeastern Texas to evaluate different herbicide options involving penoxsulam, propanil, triclopyr, halosulfuron, bispyribac-sodium, bensulfuron, and quinclorac for alligatorweed control in conventional drill-seeded rice when applied at early POST (EPOST), late POST (LPOST), or both. Among the herbicide options evaluated, penoxsulam alone (up to 83%), penoxsulam plus triclopyr (up to 87%), or bispyribac-sodium plus triclopyr (92%) provided superior alligatorweed control. Plots treated with penoxsulam plus triclopyr EPOST produced the highest yields (9,550 kg ha−1), which were comparable to plots receiving penoxsulam plus triclopyr LPOST (9,320 kg ha−1), penoxsulam alone EPOST (9,280 kg ha−1), and penoxsulam plus halosulfuron LPOST (9,180 kg ha−1). Considering both weed control and rice grain yields, penoxsulam plus triclopyr applied EPOST was found to be the best option among the treatments tested. The treatments bensulfuron alone, bensulfuron plus propanil, penoxsulam plus propanil, triclopyr plus propanil, and bispyribac-sodium plus propanil provided poor (≤ 65%) alligatorweed control. Results also suggest the likelihood for antagonistic interactions when tank-mix combinations tested in this study included propanil.

Palmer Amaranth (Amaranthus palmeri) Control by Glufosinate plus Fluometuron Applied Postemergence to WideStrike®Cotton

2013 ◽  
Vol 27 (2) ◽  
pp. 291-297 ◽  
Author(s):  
Kelly A. Barnett ◽  
A. Stanley Culpepper ◽  
Alan C. York ◽  
Lawrence E. Steckel
Keyword(s):  
United States ◽  
Weed Control ◽  
Acetolactate Synthase ◽  
The United States ◽  
Palmer Amaranth ◽  
Effective Control ◽  
Yield Response ◽  
Amaranthus Palmeri ◽  
Cotton Yield ◽  
Cotton Cultivar

Glyphosate-resistant (GR) weeds, especially GR Palmer amaranth, are very problematic for cotton growers in the Southeast and Midsouth regions of the United States. Glufosinate can control GR Palmer amaranth, and growers are transitioning to glufosinate-based systems. Palmer amaranth must be small for consistently effective control by glufosinate. Because this weed grows rapidly, growers are not always timely with applications. With widespread resistance to acetolactate synthase-inhibiting herbicides, growers have few herbicide options to mix with glufosinate to improve control of larger weeds. In a field study using a WideStrike®cotton cultivar, we evaluated fluometuron at 140 to 1,120 g ai ha−1mixed with the ammonium salt of glufosinate at 485 g ae ha−1for control of GR Palmer amaranth 13 and 26 cm tall. Standard PRE- and POST-directed herbicides were included in the systems. Glufosinate alone injured the WideStrike® cotton less than 10%. Fluometuron increased injury up to 25% but did not adversely affect yield. Glufosinate controlled 13-cm Palmer amaranth at least 90%, and there was no improvement in weed control nor a cotton yield response to fluometuron mixed with glufosinate. Palmer amaranth 26 cm tall was controlled only 59% by glufosinate. Fluometuron mixed with glufosinate increased control of the larger weeds up to 28% and there was a trend for greater yields. However, delaying applications until weeds were 26 cm reduced yield 22% relative to timely application. Our results suggest fluometuron mixed with glufosinate may be of some benefit when attempting to control large Palmer amaranth. However, mixing fluometuron with glufosinate is not a substitute for a timely glufosinate application.

scholarly journals Coarse Woody Debris in Southern United States Loblolly Pine Plantations: From Stand-Level to Regional Scales

2011 ◽  
Vol 35 (4) ◽  
pp. 161-169 ◽  
Author(s):  
Huei-Jin Wang ◽  
Philip J. Radtke ◽  
Stephen P. Prisley
Keyword(s):  
United States ◽  
Loblolly Pine ◽  
Coarse Woody Debris ◽  
Power Plants ◽  
Woody Debris ◽  
Dry Weight ◽  
Pine Plantations ◽  
Southern United States ◽  
Carbon Equivalent ◽  
Regional Forest

Abstract Broad-scale estimates of coarse woody debris (CWD) yield across landscapes are somewhat rare, despite the importance of CWD in ecosystem functioning and its potential role in terrestrial carbon cycles. Yields of CWD were estimated at regional scales by linking a stand-level predictive model with regional forest inventory data for 11 states in the southern United States. We estimated that the accumulation of CWD in late-rotation loblolly pine plantations across the South totals 48.67 million metric tons of dry wood necromass, the carbon equivalent of 24.33 million metric tons. This represents annual CO2 emissions of 21 coal-fired power plants, or the amount of carbon sequestered each year in 7 million ha of pine forests. Confidence intervals for CWD dry weight per hectare generally did not exceed ±25% of the estimated values. Although county-level estimates were of higher uncertainty, the spatial pattern appeared to be relatively consistent with the extent of loblolly pine, with low yields near the extremes of the species' natural range and high yields in extensively forested portions of its range. Quantifying regional carbon stores of CWD with respect to stand-level management activities may improve accuracy of regional estimates and provide further insight into management effects on the carbon pool and the carbon cycle.

Effects of Temperature and Photoperiod on Texas Panicum (Panicum texanum) and Wild Proso Millet (Panicum miliaceum)

Weed Science ◽  
1986 ◽  
Vol 34 (6) ◽  
pp. 876-882 ◽  
Author(s):  
David T. Patterson ◽  
Ann E. Russell ◽  
David A. Mortensen ◽  
Robert D. Coffin ◽  
Elizabeth P. Flint
Keyword(s):  
United States ◽  
Vegetative Growth ◽  
Dry Matter ◽  
Dry Weight ◽  
Growing Season ◽  
Southern United States ◽  
Panicum Miliaceum ◽  
Proso Millet ◽  
Effects Of Temperature ◽  
Total Dry Weight

Texas panicum (Panicum texanumBuckl. # PANTE) is a native of the Southwest, now increasing as a weed throughout the southern United States, whereas wild proso millet (Panicum miliaceumL. # PANMI) is an introduced weed currently increasing in importance in the northern Midwest. In controlled-environment chambers, both species produced more tillers, greater leaf area, and more total dry weight at 30/24 C day/night (simulated growing season temperature in Georgia) than at 24/18 C (simulated growing season temperature in Minnesota). Texas panicum accumulated more dry matter at 30/24 C than did wild proso millet, while wild proso millet accumulated more dry matter at 24/18 C than did Texas panicum. When the two species were grown together, Texas panicum was the superior competitor at 30/24 C while wild proso millet was superior at 24/18 C. Exposure to short photoperiods at an intermediate temperature of 27/21 C accelerated flowering and limited vegetative growth in both species. In the range of photoperiods (10 to 16 h) examined, wild proso millet always flowered earlier and, consequently, produced less vegetative growth than Texas panicum. Its responses to temperature and photoperiod indicate that wild proso millet probably would be competitively inferior to Texas panicum and other adapted grass weeds in the southern United States.

Management of glyphosate-resistant Palmer amaranth (Amaranthus palmeri) in 2,4-D–, glufosinate-, and glyphosate-resistant soybean

2020 ◽  
pp. 1-8
Author(s):  
Chandrima Shyam ◽  
Parminder S. Chahal ◽  
Amit J. Jhala ◽  
Mithila Jugulam
Keyword(s):  
United States ◽  
Field Experiments ◽  
The United States ◽  
Palmer Amaranth ◽  
Amaranthus Palmeri ◽  
Soybean Yield ◽  
Chlorimuron Ethyl ◽  
Density And Biomass ◽  
Herbicide Programs ◽  
Biomass Reduction

Abstract Glyphosate-resistant (GR) Palmer amaranth is a problematic, annual broadleaf weed in soybean production fields in Nebraska and many other states in the United States. Soybean resistant to 2,4-D, glyphosate, and glufosinate (Enlist E3TM) has been developed and was first grown commercially in 2019. The objectives of this research were to evaluate the effect of herbicide programs applied PRE, PRE followed by (fb) late-POST (LPOST), and early-POST (EPOST) fb LPOST on GR Palmer amaranth control, density, and biomass reduction, soybean injury, and yield. Field experiments were conducted near Carleton, NE, in 2018, and 2019 in a grower’s field infested with GR Palmer amaranth in 2,4-D–, glyphosate-, and glufosinate-resistant soybean. Sulfentrazone + cloransulam-methyl, imazethapyr + saflufenacil + pyroxasulfone, and chlorimuron ethyl + flumioxazin + metribuzin applied PRE provided 84% to 97% control of GR Palmer amaranth compared with the nontreated control 14 d after PRE. Averaged across herbicide programs, PRE fb 2,4-D and/or glufosinate, and sequential application of 2,4-D or glufosinate applied EPOST fb LPOST resulted in 92% and 88% control of GR Palmer amaranth, respectively, compared with 62% control with PRE-only programs 14 d after LPOST. Reductions in Palmer amaranth biomass followed the same trend; however, Palmer amaranth density was reduced 98% in EPOST fb LPOST programs compared with 91% reduction in PRE fb LPOST and 76% reduction in PRE-only programs. PRE fb LPOST and EPOST fb LPOST programs resulted in an average soybean yield of 4,478 and 4,706 kg ha−1, respectively, compared with 3,043 kg ha−1 in PRE-only programs. Herbicide programs evaluated in this study resulted in no soybean injury. The results of this research illustrate that herbicide programs are available for the management of GR Palmer amaranth in 2,4-D–, glyphosate-, and glufosinate-resistant soybean.

Critical timing of Palmer amaranth (Amaranthus palmeri) removal in sweetpotato

2020 ◽  
Vol 34 (4) ◽  
pp. 547-551 ◽  
Author(s):  
Stephen C. Smith ◽  
Katherine M. Jennings ◽  
David W. Monks ◽  
Sushila Chaudhari ◽  
Jonathan R. Schultheis ◽  
...  
Keyword(s):  
North Carolina ◽  
Logistic Model ◽  
Yield Loss ◽  
Relative Yield ◽  
Field Studies ◽  
Palmer Amaranth ◽  
Amaranthus Palmeri ◽  
Marketable Yield ◽  
Yield Data ◽  
Critical Timing

AbstractPalmer amaranth is the most common and troublesome weed in North Carolina sweetpotato. Field studies were conducted in Clinton, NC, in 2016 and 2017 to determine the critical timing of Palmer amaranth removal in ‘Covington’ sweetpotato. Palmer amaranth was grown with sweetpotato from transplanting to 2, 3, 4, 5, 6, 7, 8, and 9 wk after transplanting (WAP) and maintained weed-free for the remainder of the season. Palmer amaranth height and shoot dry biomass increased as Palmer amaranth removal was delayed. Season-long competition by Palmer amaranth interference reduced marketable yields by 85% and 95% in 2016 and 2017, respectively. Sweetpotato yield loss displayed a strong inverse linear relationship with Palmer amaranth height. A 0.6% and 0.4% decrease in yield was observed for every centimeter of Palmer amaranth growth in 2016 and 2017, respectively. The critical timing for Palmer amaranth removal, based on 5% loss of marketable yield, was determined by fitting a log-logistic model to the relative yield data and was determined to be 2 WAP. These results show that Palmer amaranth is highly competitive with sweetpotato and should be managed as early as possible in the season. The requirement of an early critical timing of weed removal to prevent yield loss emphasizes the importance of early-season scouting and Palmer amaranth removal in sweetpotato fields. Any delay in removal can result in substantial yield reductions and fewer premium quality roots.

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