Control of waterhemp (Amaranthus tuberculatus) regrowth after failed applications of glufosinate or fomesafen

2020 ◽  
Vol 34 (6) ◽  
pp. 794-800
Author(s):  
Jesse A. Haarmann ◽  
Bryan G. Young ◽  
William G. Johnson
Keyword(s):  
Seed Production ◽  
Optimum Combination ◽  
Bare Ground ◽  
Herbicide Application ◽  
Application Timing ◽  
Previous Injury ◽  
Crop Tolerance ◽  
Initial Application ◽  
Site Of Action ◽  
Amaranthus Tuberculatus

AbstractFoliar herbicide applications to waterhemp can result in inadequate control, leading to subsequent regrowth that often necessitates a second herbicide application to prevent crop interference and seed production. The most effective herbicides and application timings are unknown in situations where waterhemp has regrown from previous injury, such as failed applications of glufosinate or fomesafen. The objective of this research was to determine the optimum combination of herbicide and time from the first failed herbicide application to a sequential herbicide application for control of waterhemp regrowth. Reduced rates of either glufosinate or fomesafen were applied to 30-cm waterhemp plants to mimic failure of the initial herbicide application in separate bare-ground experiments. Respray treatments of glufosinate, fomesafen, lactofen, 2,4-D, or dicamba were applied 3, 7, or 11 d after the initial application. Glufosinate and fomesafen as respray treatments resulted in 90% to 100% control of waterhemp regardless of application timing following a failed glufosinate application. After a failed application of fomesafen, applying glufosinate or 2,4-D resulted in 87% to 99% control of waterhemp. Waterhemp control with fomesafen and lactofen was 13% to 21% greater, respectively, when those treatments followed glufosinate compared with fomesafen as the initial herbicides. On the basis of these results, glufosinate and fomesafen should be used for respray situations after inadequate control from glufosinate; and 2,4-D or glufosinate should be used for respray situations following inadequate control from fomesafen where crop tolerance and herbicide product labels allow. Although glufosinate followed by glufosinate was very effective for controlling waterhemp regrowth, caution should be exercised to avoid sequential application of herbicide with the same site of action.

scholarly journals Responses of a Waterhemp (Amaranthus tuberculatus) Population Resistant to HPPD-Inhibiting Herbicides to Foliar-Applied Herbicides

2016 ◽  
Vol 30 (1) ◽  
pp. 106-115 ◽  
Author(s):  
Nicholas E. Hausman ◽  
Patrick J. Tranel ◽  
Dean E. Riechers ◽  
Aaron G. Hager
Keyword(s):  
Photosystem Ii ◽  
Field Data ◽  
Growth Stage ◽  
Acetolactate Synthase ◽  
Herbicide Application ◽  
Greenhouse Experiments ◽  
County Population ◽  
Site Of Action ◽  
Amaranthus Tuberculatus ◽  
Action Groups

Field and greenhouse experiments were conducted to characterize the response of a waterhemp population from McLean County, IL to foliar-applied 4-hydroxyphenylpyruvate dioxygenase (HPPD) –inhibiting herbicides and determine the population's sensitivity to herbicides from other site-of-action groups. In the field, 10 to 15–cm-tall waterhemp treated with mesotrione at 105 g ai ha−1, tembotrione at 92 g ai ha−1, or topromezone at 18 g ai ha−1had significantly greater biomass (≥ 10%) 14 d after treatment (DAT) than waterhemp harvested the day of herbicide application, indicating growth had occurred following herbicide application. Waterhemp growth stage at the time of herbicide application influenced control. Mesotrione applied at 105 g ha−1alone or combined with atrazine at 560 g ai ha−1provided significantly greater waterhemp control (≥ 66%) when applied to small waterhemp plants (2 to 5 cm tall) compared with applications made to plants 5 to 10 or 10 to 15 cm tall. Glyphosate, glufosinate, fomesafen, lactofen, or acifluorfen provided greater waterhemp control (≥ 68%) 7 and 14 DAT than mesotrione, dicamba, or 2,4-D. Control of this population with atrazine, chlorimuron, and imazethapyr did not exceed 12%. Results of a greenhouse experiment with waterhemp plants grown from field-collected seed were similar to field data, and confirm the McLean County population was poorly controlled with HPPD, photosystem II, and acetolactate synthase inhibitors.

scholarly journals Palmer amaranth control, fecundity, and seed viability from soybean herbicides applied at first female inflorescence

2020 ◽  
pp. 1-7
Author(s):  
Eric B. Scruggs ◽  
Mark J. VanGessel ◽  
David L. Holshouser ◽  
Michael L. Flessner
Keyword(s):  
Seed Production ◽  
Seed Viability ◽  
Palmer Amaranth ◽  
Flower Initiation ◽  
Full Potential ◽  
Herbicide Application ◽  
Female Inflorescence ◽  
Site Of Action ◽  
Auxin Herbicides ◽  
Effective Site

Abstract Palmer amaranth is an extremely troublesome weed for soybean growers because of its aggressive growth, adaptability, prolific seed production, and widespread resistance to many herbicides. Studies were initiated to determine the effects of herbicide application at first female inflorescence on Palmer amaranth control, biomass, seed production, cumulative germination, and seed viability. Enlist (2,4-D–resistant) soybean and Xtend (dicamba-resistant) soybean were planted and various combinations of either 2,4-D or dicamba with and without glufosinate and/or glyphosate were applied at first visible female Palmer amaranth inflorescence. Mixtures of 2,4-D + glufosinate and 2,4-D + glufosinate + glyphosate provided the greatest control at 4 wk after treatment in Enlist soybean. Similarly, in Xtend soybean, combinations of dicamba + glufosinate and dicamba + glufosinate + glyphosate provided the greatest control. The greatest reductions in biomass were from combinations of auxin herbicides (2,4-D or dicamba) plus glufosinate with and without glyphosate. Seed production was reduced most by treatments containing at least one effective site of action: an auxin herbicide (2,4-D or dicamba) or glufosinate. In contrast to previous research, cumulative germination and seed viability were not affected by herbicide treatments. This research indicates the efficacy of auxin herbicides or glufosinate alone and in combination to reduce the seed production of Palmer amaranth when applied at first female inflorescence. More research is needed to evaluate the full potential for applications of these herbicides at flower initiation to mitigate the evolution of herbicide resistance.

Control of Palmer Amaranth (Amaranthus palmeri) Regrowth Following Failed Applications of Glufosinate and Fomesafen

2021 ◽  
pp. 1-21
Author(s):  
Jesse A. Haarmann ◽  
Bryan G. Young ◽  
William G. Johnson
Keyword(s):  
Field Experiments ◽  
Palmer Amaranth ◽  
Amaranthus Palmeri ◽  
Bare Ground ◽  
Herbicide Application ◽  
Ground Field ◽  
Initial Application ◽  
Percentage Points ◽  
Herbicide Treatment ◽  
Postemergence Herbicides

Abstract Rapid vegetative growth and adverse application conditions are common factors leading to the failure of postemergence herbicides on Palmer amaranth. A sequential herbicide application, or respray, is often necessary to control weeds that have survived the initial herbicide application to protect crop yield and minimize weed seed production. The optimum timing after the initial application and the most effective herbicide for control of Palmer amaranth has not been characterized. The objectives of these experiments were to determine the optimum herbicide for treating Palmer amaranth regrowth, the optimum timing for each of those herbicides, and how the initial failed herbicide might affect efficacy of a second herbicide application. Bare ground field experiments were performed in 2017 and 2018 in which glufosinate or fomesafen herbicide failure was induced on Palmer amaranth plants that were 30 cm in height. Respray treatments of glufosinate, fomesafen, lactofen, 2,4-D, and dicamba were applied once at timings of 4 to 5 days, 7 days, or 11 days after the initial spray application. Nearly all herbicide treatment and timing combinations increased control by at least 13 percentage points compared to no respray herbicide treatment. Regardless of initial herbicide, glufosinate applied as a respray treatment was the most consistent and efficacious with up to 97% control. The specific herbicide used in the second application impacted final weed control more so than timing of the respray application. For instance, control by glufosinate respray treatments was 10 to 18 percentage points greater than control from lactofen respray treatments, whereas control decreased by 3 percentage points when respray applications of any herbicide were made 11 days after initial application of glufosinate compared to 4 to 5 and 7 days after initial application of glufosinate. In the event of failure to control Palmer amaranth with glufosinate or fomesafen, glufosinate should be applied in order to maximize control.

scholarly journals Do applications of systemic herbicides when green fruit are present prevent seed production or viability of Alliaria petiolata (garlic mustard)?

2021 ◽  
pp. 1-17
Author(s):  
Leo Roth ◽  
José Luiz C. S. Dias ◽  
Christopher Evans ◽  
Kevin Rohling ◽  
Mark Renz
Keyword(s):  
Seed Production ◽  
Seed Viability ◽  
Early Spring ◽  
Alliaria Petiolata ◽  
Late Spring ◽  
Garlic Mustard ◽  
Viable Seed ◽  
Application Timing ◽  
Control Seed ◽  
Second Year

Garlic mustard [Alliaria petiolata (M. Bieb.) Cavara & Grande] is a biennial invasive plant commonly found in the northeastern and midwestern United States. Although it is not recommended to apply herbicides after flowering, land managers frequently desire to conduct management during this timing. We applied glyphosate and triclopyr (3% v/v and 1% v/v using 31.8% and 39.8% acid equivalent formulations, respectively) postemergence to established, second-year A. petiolata populations at three locations when petals were dehiscing, and evaluated control, seed production and seed viability. Postemergence glyphosate applications at this timing provided 100% control of A. petiolata by 4 weeks after treatment at all locations whereas triclopyr efficacy was variable, providing 38-62% control. Seed production was only reduced at one location, with similar results regardless of treatment. Percent seed viability was also reduced, and when combined with reductions in seed production, we found a 71-99% reduction in number of viable seed produced plant-1 regardless of treatment. While applications did not eliminate viable seed production, our findings indicate that glyphosate and triclopyr applied while petals were dehiscing is a viable alternative to cutting or hand-pulling at this timing as it substantially decreased viable A. petiolata seed production. Management Implications Postemergence glyphosate and triclopyr applications in the early spring to rosettes are standard treatments used to manage A. petiolata. However, weather and other priorities limit the window for management, forcing field practitioners to utilize more labor-intensive methods such as hand-pulling. It is not known how late in the development of A. petiolata these herbicides can be applied to prevent viable seed production. Since prevention of soil seedbank replenishment is a key management factor for effective long-term control of biennial invasive species, we hypothesized late spring foliar herbicide applications to second year A. petiolata plants when flower petals were dehiscing could be an effective management tool if seed production or viability is eliminated. Our study indicated that glyphosate applications at this timing provided 100% control of A. petiolata plants by 4 weeks after treatment at all locations, whereas triclopyr efficacy was inconsistent. Although both glyphosate and triclopyr decreased viable seed production to nearly zero at one of our three study locations, the same treatments produced significant amounts of viable seed at the other two locations. Our findings suggest late spring glyphosate and triclopyr applications should not be recommended over early spring applications to rosettes for A. petiolata management, as our late spring application timing did not prevent viable seed production, and may require multiple years of implementation to eradicate populations. Nonetheless, this application timing holds value in areas devoid of desirable understory vegetation compared to no management practices or mechanical management options including hand-pulling when fruit are present, as overall viable seed production was reduced to similar levels as these treatments.

scholarly journals Spray Drift Generated in Vineyard during Under-Row Weed Control and Suckering: Evaluation of Direct and Indirect Drift-Reducing Techniques

2020 ◽  
Vol 12 (12) ◽  
pp. 5068 ◽  
Author(s):  
Marco Grella ◽  
Paolo Marucco ◽  
Athanasios T. Balafoutis ◽  
Paolo Balsari
Keyword(s):  
Weed Control ◽  
Experimental Work ◽  
Environmental Issues ◽  
Buffer Zone ◽  
Optimum Combination ◽  
Spray Drift ◽  
Spray Application ◽  
Herbicide Application ◽  
Spray Applications

The most widespread method for weed control and suckering in vineyards is under-row band herbicide application. It could be performed for weed control only (WC) or weed control and suckering (WSC) simultaneously. During herbicide application, spray drift is one of the most important environmental issues. The objective of this experimental work was to evaluate the performance of specific Spray Drift Reducing Techniques (SDRTs) used either for WC or WSC spray applications. Furthermore, spray drift reduction achieved by buffer zone adoption was investigated. All spray drift measurements were conducted according to ISO22866:2005 protocol. Sixteen configurations deriving from four nozzle types (two conventional and two air-induction—AI) combined with or without a semi-shielded boom at two different heights (0.25 m for WC and 0.50 m for WSC) were tested. A fully-shielded boom was also tested in combination with conventional nozzles at 0.25 m height for WC. Ground spray drift profiles were obtained, from which corresponding Drift Values (DVs) were calculated. Then, the related drift reduction was calculated based on ISO22369-1:2006. It was revealed that WC spray applications generate lower spray drift than WSC applications. In all cases, using AI nozzles and semi-shielded boom significantly reduced DVs; the optimum combination of SDRTs decreased spray drift by up to 78% and 95% for WC and WSC spray application, respectively. The fully-shielded boom allowed reducing nearly 100% of spray drift generation. Finally, the adoption of a cropped buffer zone that includes the two outermost vineyard rows lowered the total spray drift up to 97%. The first 90th percentile model for the spray drift generated during herbicide application in vineyards was also obtained.

Monitoring ley pastures and their response to winter cleaning

2006 ◽  
Vol 46 (8) ◽  
pp. 1023 ◽  
Author(s):  
E. C. Wolfe ◽  
J. A. Paul ◽  
P. D. Cregan
Keyword(s):  
Rapid Development ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Total Biomass ◽  
Seedling Density ◽  
Bare Ground ◽  
Herbicide Application ◽  
Seeding Rate ◽  
The Impact ◽  
Legume Growth

The purposes of this study were to evaluate subterranean clover-based leys on farms and in experiments using several pasture parameters, and to assess the impact of winter cleaning on the productivity and botanical composition of clover swards. Annual pastures were monitored on a group of 5 farms in the Wagga district and compared with an experimental subterranean clover (Trifolium subterraneum L.) pasture. The major problem in the farm paddocks was a lack of legume biomass due to poor legume densities, a consequence of the use of the soft-seeded cultivar Woogenellup and a high content of grassy weeds. The farmers in the group were unaware of the tools, parameters and benchmarks for making quantitative pasture comparisons. In 2 experiments, a range of subterranean clover swards were generated through the use of cultivars, seeding rate and winter cleaning treatments, grazed at 15 sheep/ha and monitored for 3 years. Appropriate benchmark values for the seed pool of subterranean clover were 300–350 kg/ha in winter and 600–700 kg/ha in summer. On the basis of both winter production, a function of May seedling density (target >1000 seedlings/m2) and spring production, which depended on the cultivar maturity, Junee was superior at Wagga to either Dalkeith (earlier maturing) or Woogenellup (softer seeded). Winter cleaning, using selective herbicides (fluazifop, simazine) to remove grasses and weeds, was advantageous in achieving a high content (>90%) and productivity of subterranean clover, provided that the legume content of the pasture was at least 28%, or >20% of total ground area before herbicide application in winter. In winter-cleaned swards, legume growth increased by up to 80%, legume biomass was improved by up to 46% and legume content increased from <50 to >95%. The main disadvantages of winter cleaning were increased areas of bare ground and reduced total biomass for several weeks after herbicide application, and the rapid development of ryegrass that was resistant to at least 1 of the herbicides used. The strategic use of observations to monitor the performance of pastures and their response to management is discussed.

Effect of tillage on timing ofSetariaspp. emergence and growth

Weed Science ◽  
1999 ◽  
Vol 47 (5) ◽  
pp. 563-570 ◽  
Author(s):  
Lizabeth A. B. Stahl ◽  
Gregg A. Johnson ◽  
Ronald L. Wyse ◽  
Douglas D. Buhler ◽  
Jeffrey L. Gunsolus
Keyword(s):  
Seed Production ◽  
Weed Management ◽  
Cropping Systems ◽  
Field Research ◽  
Herbicide Application ◽  
Tillage Systems ◽  
Early Application ◽  
Setaria Faberi ◽  
Tillage System ◽  
Soil Seedbank

Weed management can be a significant challenge in cropping systems, partly because the effects of tillage systems on weed seedbank and seedling population dynamics are not well understood. Field research was conducted from 1994 to 1996 in established tillage plots consisting of moldboard plow (MP), chisel plow (CP), and no-tillage (NT). The objectives were to determine the effects of long-term tillage systems on the timing and duration ofSetariaspp. emergence and percentage cumulative emergence from the soil seedbank and to investigate the effect of tillage onSetariaspp. density and seed production following glyphosate application atSetariaspp. heights of 5, 10, and 15 cm. NT contained a greater number ofSetariaspp. seed in the 0- to 1-, 1- to 3-, and 3- to 6-cm depths than MP or CP systems. There was little difference between the three tillage systems at depths greater than 6 cm.Setariaspp. emergence was greater in NT than in MP or CP in 1994 and 1996 and greater than in MP in 1995. There was a substantial increase inSetariaspp. emergence in NT between 3 and 4 weeks after planting (WAP) in 1994 and between 5 and 6 WAP in 1995 and 1996. Significant emergence did not occur past 5 to 6 WAP in 1994 and 1995 but continued over a longer period of time in 1996.Setariaspp. plants consistently reached targeted herbicide application heights 4 to 9 d earlier in NT than in CP and MP. In 1994, finalSetariaspp. density was greater in NT compared to CP and MP at the 5- and 10-cm herbicide application timings. When glyphosate was applied to 15-cm-tallSetaria, very few weeds were present following application across all tillage systems. In 1995, NT resulted in greaterSetariaspp. density than MP or CP across all application timings. There was no difference in finalSetariaspp. density between MP and CP across all glyphosate timings in 1994 and 1995. Seed production was negligible in MP and CP, regardless of glyphosate timing. In NT, however, significant seed production occurred, especially with early application. Results indicate that the effectiveness of nonresidual herbicides forSetaria faberiHerrm. control is influenced by tillage system and the timing of application.

Effects of Herbicide Application Timing on Johnsongrass (Sorghum halepense) and Pitted Morningglory (Ipomoea lacunosa) Control

1990 ◽  
Vol 4 (4) ◽  
pp. 900-903 ◽  
Author(s):  
David R. Shaw ◽  
Sunil Ratnayake ◽  
Clyde A. Smith
Keyword(s):  
Growth Stage ◽  
Field Experiments ◽  
Sorghum Halepense ◽  
Herbicide Application ◽  
Ipomoea Lacunosa ◽  
Application Timing ◽  
Final Treatment ◽  
Pitted Morningglory

Field experiments were conducted to evaluate the influence of application timing of imazethapyr and fluazifop-P on rhizome johnsongrass and pitted morningglory control in soybean. Herbicides were applied at three timings keyed to johnsongrass heights of 15, 30, and 60 cm and 3-, 6-, and 9-leaf pitted morningglory. Evaluations 6 wk after the final treatment indicated imazethapyr controlled both species best when applied at the 15-cm johnsongrass growth stage. Increasing imazethapyr rate did not increase control of pitted morningglory, but did increase johnsongrass control at the 15-cm application timing. However, at the 30-cm johnsongrass application timing, increasing the rate from 0.07 to 0.10 kg ha-1improved control of both species. Johnsongrass control with imazethapyr was no more than 64% when applications were delayed to 30-cm or larger johnsongrass. Fluazifop-P controlled johnsongrass well at all timings.

The influence of soybean population and POST herbicide application timing on in-season and subsequent-season Palmer amaranth (Amaranthus palmeri) control and economic returns

2020 ◽  
pp. 1-7
Author(s):  
Denis J. Mahoney ◽  
David L. Jordan ◽  
Andrew T. Hare ◽  
Nilda Roma-Burgos ◽  
Katherine M. Jennings ◽  
...  
Keyword(s):  
Weed Control ◽  
High Density ◽  
Palmer Amaranth ◽  
Economic Returns ◽  
Herbicide Application ◽  
Application Timing ◽  
Herbicide Resistant ◽  
Resistance Evolution ◽  
Subsequent Crop ◽  
Density Population

Abstract Overreliance on herbicides for weed control has led to the evolution of herbicide-resistant Palmer amaranth populations. Farm managers should consider the long-term consequences of their short-term management decisions, especially when considering the soil weed seedbank. The objectives of this research were to (1) determine how soybean population and POST herbicide application timing affects in-season Palmer amaranth control and soybean yield, and (2) how those variables influence Palmer amaranth densities and cotton yields the following season. Soybeans were planted (19-cm row spacing) at a low-, medium-, and high-density population (268,000, 546,000, and 778,000 plants ha–1, respectively). Fomesafen and clethodim (280 and 210 g ai ha–1, respectively) were applied at the VE, V1, or V2 to V3 soybean growth stage. Nontreated plots were also included to assess the effect of soybean population alone. The following season, cotton was planted into these plots so as to understand the effects of soybean planting population on Palmer amaranth densities in the subsequent crop. When an herbicide application occurred at the V1 or V2 to V3 soybean stage, weed control in the high-density soybean population increased 17% to 23% compared to the low-density population. Economic return was not influenced by soybean population and was increased 72% to 94% with herbicide application compared to no treatment. In the subsequent cotton crop, Palmer amaranth densities were 24% to 39% lower 3 wk after planting when following soybean sprayed with herbicides compared to soybean without herbicides. Additionally, Palmer amaranth densities in cotton were 19% lower when soybean was treated at the VE stage compared to later stages. Thus, increasing soybean population can improve Palmer amaranth control without adversely affecting economic returns and can reduce future weed densities. Reducing the weed seedbank and selection pressure from herbicides are critical in mitigating resistance evolution.

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