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

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.

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

Weed Technology ◽

10.1017/wet.2020.58 ◽

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.

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Nontarget-Site Resistance to ALS Inhibitors in Waterhemp (Amaranthus tuberculatus)

Weed Science ◽

10.1614/ws-d-14-00139.1 ◽

2015 ◽

Vol 63 (2) ◽

pp. 399-407 ◽

Cited By ~ 31

Author(s):

Jiaqi Guo ◽

Chance W. Riggins ◽

Nicholas E. Hausman ◽

Aaron G. Hager ◽

Dean E. Riechers ◽

...

Keyword(s):

Acetolactate Synthase ◽

Enzyme Assays ◽

Whole Plant ◽

Site Of Action ◽

Amaranthus Tuberculatus ◽

Resistance Trait ◽

Als Inhibitors ◽

Moderate Resistance ◽

Inhibitor Resistance ◽

Als Inhibitor

A waterhemp population (MCR) previously characterized as resistant to 4-hydroxyphenylpyruvate dioxygenase and photosystem II inhibitors demonstrated both moderate and high levels of resistance to acetolactate synthase (ALS) inhibitors. Plants from the MCR population exhibiting high resistance to ALS inhibitors contained the commonly found Trp574Leu ALS amino acid substitution, whereas plants with only moderate resistance did not have this substitution. A subpopulation (JG11) was derived from the MCR population in which the moderate-resistance trait was isolated from the Trp574Leu mutation. Results from DNA sequencing and ALS enzyme assays demonstrated that resistance to ALS inhibitors in the JG11 population was not due to an altered site of action. This nontarget-site ALS-inhibitor resistance was characterized with whole-plant dose–response experiments using herbicides from each of the five commercialized families of ALS-inhibiting herbicides. Resistance ratios ranging from 3 to 90 were obtained from the seven herbicides evaluated. Nontarget-site resistance to ALS has been rarely documented in eudicot weeds, and adds to the growing list of resistance traits evolved in waterhemp.

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Identification of a Tall Waterhemp (Amaranthus tuberculatus) Biotype Resistant to HPPD-Inhibiting Herbicides, Atrazine, and Thifensulfuron in Iowa

Weed Technology ◽

10.1614/wt-d-10-00150.1 ◽

2011 ◽

Vol 25 (3) ◽

pp. 514-518 ◽

Cited By ~ 38

Author(s):

Patrick M. McMullan ◽

Jerry M. Green

Keyword(s):

Photosystem Ii ◽

Field Tests ◽

Acetolactate Synthase ◽

Field Conditions ◽

Herbicide Resistant ◽

Seed Corn ◽

Modes Of Action ◽

Henry County ◽

Amaranthus Tuberculatus ◽

Als Inhibitors

Seeds of a putative 4-hydroxyphenylpyruvate dioxygenase (HPPD)-inhibiting herbicide–resistant tall waterhemp biotype from Henry County, IA, were collected from a seed corn field in fall 2009 after plants were not controlled following a POST application of mesotrione plus atrazine. The response of this biotype to various herbicide modes of action was evaluated in greenhouse and field tests. Under greenhouse conditions, the suspect biotype showed an eightfold decrease in sensitivity to mesotrione with a 50% control rate of 21 g ha−1compared with 2.7 g ha−1for the susceptible biotype. The biotype also had a 10-fold decrease in sensitivity to atrazine and a 28-fold decrease in sensitivity to thifensulfuron. Under field conditions, tall waterhemp was not controlled POST at the label rate of 1,100 g ha−1of atrazine. Tall waterhemp control was less than 60% at the label rates of three commonly used POST HPPD-inhibiting herbicides in seed corn: 105 g ha−1of mesotrione, 92 g ha−1of tembotrione, or 18 g ha−1of topramezone. Thus, this new tall waterhemp biotype is resistant to three herbicide modes of action: HPPD inhibitors, photosystem-II inhibitors, and acetolactate synthase (ALS) inhibitors.

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Multiple Resistance to Herbicides from Four Site-of-Action Groups in Waterhemp (Amaranthus tuberculatus)

Weed Science ◽

10.1614/ws-d-12-00166.1 ◽

2013 ◽

Vol 61 (3) ◽

pp. 460-468 ◽

Cited By ~ 65

Author(s):

Michael S. Bell ◽

Aaron G. Hager ◽

Patrick J. Tranel

Keyword(s):

Field Experiments ◽

Acetolactate Synthase ◽

Glyphosate Resistance ◽

The United States ◽

Multiple Resistance ◽

Site Mutation ◽

High Frequencies ◽

Site Of Action ◽

Resistance To Herbicides ◽

Action Groups

In 2006 and 2007, farmers from two counties in Illinois reported failure to control waterhemp with glyphosate. Subsequent onsite field experiments revealed that the populations might be resistant to multiple herbicides. Greenhouse experiments therefore were conducted to confirm glyphosate resistance, and to test for multiple resistance to other herbicides, including atrazine, acifluorfen, lactofen, and imazamox. In glyphosate dose-response experiments, both populations responded similarly to a previously characterized glyphosate-resistant population (MO1). Both Illinois populations also demonstrated high frequencies of resistance to the acetolactate synthase (ALS) inhibitor, imazamox. Additionally, one of the populations demonstrated high frequencies of resistance to both atrazine and the protoporphyrinogen oxidase (PPO) inhibitor, lactofen. Furthermore, using combinations of sequential and tank-mix herbicide applications, individual plants resistant to herbicides spanning all four site-of-action groups were identified from one population. Molecular experiments were performed to provide an initial characterization of the resistance mechanisms and to provide confirmation of the presence of multiple resistance traits within the two populations. Both populations contained the W574L ALS mutation and the ΔG210 PPO mutation, previously shown to confer resistance to ALS and PPO inhibitors, respectively. Atrazine resistance in both populations is suspected to be metabolism-based, because a triazine target-site mutation was not identified. A P106S EPSPS mutation, previously reported to confer glyphosate resistance, was identified in one population. This mutation was identified in both resistant and sensitive plants from the population; however, and so more research is needed to determine the glyphosate-resistance mechanism(s). This is the first known case of a weed population in the United States possessing multiple resistance to herbicides from four site-of-action groups.

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Hormesis with glyphosate depends on coffee growth stage

Anais da Academia Brasileira de Ciências ◽

10.1590/s0001-37652013005000027 ◽

2013 ◽

Vol 85 (2) ◽

pp. 813-822 ◽

Cited By ~ 25

Author(s):

LEONARDO B. DE CARVALHO ◽

PEDRO L.C.A. ALVES ◽

STEPHEN O. DUKE

Keyword(s):

Plant Growth ◽

Weed Management ◽

Growth Stage ◽

Growth Stages ◽

Coffee Plant ◽

Herbicide Application ◽

Coffee Plantations ◽

Plant Growth Stages ◽

Coffee Plants ◽

Almost All

Weed management systems in almost all Brazilian coffee plantations allow herbicide spray to drift on crop plants. In order to evaluate if there is any effect of the most commonly used herbicide in coffee production, glyphosate, on coffee plants, a range of glyphosate doses were applied directly on coffee plants at two distinct plant growth stages. Although growth of both young and old plants was reduced at higher glyphosate doses, low doses caused no effects on growth characteristics of young plants and stimulated growth of older plants. Therefore, hormesis with glyphosate is dependent on coffee plant growth stage at the time of herbicide application.

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Sulfentrazone efficiency on Ipomoea hederifolia and Ipomoea quamoclit as influenced by rain and sugarcane straw

Planta Daninha ◽

10.1590/s0100-83582013000100018 ◽

2013 ◽

Vol 31 (1) ◽

pp. 165-174 ◽

Cited By ~ 6

Author(s):

N.M Correia ◽

E.H Camilo ◽

E.A Santos

Keyword(s):

Field Experiment ◽

Biological Effects ◽

Soil Surface ◽

Time Interval ◽

Herbicide Application ◽

Time Intervals ◽

Greenhouse Experiments ◽

Sugarcane Straw ◽

Simulated Rain ◽

Rain Simulation

The aim of this study was to assess the capacity of sulfentrazone applied in pre-emergence in controlling Ipomoea hederifolia and Ipomoea quamoclit as a function of the time interval between herbicide application and the occurrence of rain, and the presence of sugarcane straw on the soil surface. Two greenhouse experiments and one field experiment were conducted. For the greenhouse experiments, the study included three doses of sulfentrazone applied by spraying 0, 0.6, and 0.9 kg ha-1, two amounts of straw on the soil (0 and 10 t ha-1), and five time intervals between the application of herbicide and rain simulation (0, 20, 40, 60, and 90 days). In the field experiment, five herbicide treatments (sulfentrazone at 0.6 and 0.9 kg ha-1, sulfentrazone + hexazinone at 0.6 + 0.25 kg ha-1, amicarbazone at 1.4 kg ha-1, and imazapic at 0.147 kg ha-1) and two controls with no herbicide were studied. Management conditions with or without sugarcane straw on the soil were also assessed. From the greenhouse experiments, sulfentrazone application at 0.6 kg ha-1 was found to provide for the efficient control of I. hederifolia and I. quamoclit in a dry environment, with up to 90 days between herbicide application and rain simulation. After herbicide application, 20 mm of simulated rain was enough to leach sulfentrazone from the straw to the soil, as the biological effects observed in I. hederifolia and I. quamoclit remained unaffected. Under field conditions, either with or without sugarcane straw left on the soil, sulfentrazone alone (0.6 or 0.9 kg ha-1) or sulfentrazone combined with hexazinone (0.6 + 0.25 kg ha-1) was effective in the control of I. hederifolia and I. quamoclit, exhibiting similar or better control than amicarbazone (1.4 kg ha-1) and imazapic (0.147 kg ha-1).

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Confirmation and Control of HPPD-Inhibiting Herbicide–Resistant Waterhemp (Amaranthus tuberculatus) in Nebraska

Weed Technology ◽

10.1017/wet.2016.4 ◽

2017 ◽

Vol 31 (1) ◽

pp. 67-79 ◽

Cited By ~ 26

Author(s):

Maxwel C. Oliveira ◽

Amit J. Jhala ◽

Todd Gaines ◽

Suat Irmak ◽

Keenan Amundsen ◽

...

Keyword(s):

Dose Response ◽

Field Conditions ◽

Effective Control ◽

Herbicide Resistant ◽

Greenhouse Experiments ◽

Amaranthus Tuberculatus ◽

Sites Of Action ◽

And Control ◽

Herbicide Programs

Field and greenhouse experiments were conducted in Nebraska to (1) confirm the 4-hydroxyphenylpyruvate dioxygenase (HPPD)-inhibiting resistant-waterhemp biotype (HPPD-RW) by quantifying the resistance levels in dose-response studies, and (2) to evaluate efficacy of PRE-only, POST-only, and PRE followed by POST herbicide programs for control of HPPD-RW in corn. Greenhouse dose-response studies confirmed that the suspected waterhemp biotype in Nebraska has evolved resistance to HPPD-inhibiting herbicides with a 2- to 18-fold resistance depending upon the type of HPPD-inhibiting herbicide being sprayed. Under field conditions, at 56 d after treatment, ≥90% control of the HPPD-RW was achieved with PRE-applied mesotrione/atrazine/S-metolachlor+acetochlor, pyroxasulfone (180 and 270 g ai ha−1), pyroxasulfone/fluthiacet-methyl/atrazine, and pyroxasulfone+saflufenacil+atrazine. Among POST-only herbicide programs, glyphosate, a premix of mesotrione/atrazine tank-mixed with diflufenzopyr/dicamba, or metribuzin, or glufosinate provided ≥92% HPPD-RW control. Herbicide combinations of different effective sites of action in mixtures provided ≥86% HPPD-RW control in PRE followed by POST herbicide programs. It is concluded that the suspected waterhemp biotype is resistant to HPPD-inhibiting herbicides and alternative herbicide programs are available for effective control in corn. The occurrence of HPPD-RW in Nebraska is significant because it limits the effectiveness of HPPD-inhibiting herbicides.

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Nicosulfuron Resistance and Metabolism in Terbufos- and Naphthalic Anhydride-Treated Corn

Weed Science ◽

10.1017/s0043174500081005 ◽

1995 ◽

Vol 43 (2) ◽

pp. 163-168 ◽

Cited By ~ 7

Author(s):

Balazs Siminszky ◽

Frederick T. Corbin ◽

Yvonna Sheldon

Keyword(s):

Laboratory Experiments ◽

Acetolactate Synthase ◽

Synergistic Interaction ◽

Differential Sensitivity ◽

Severe Injury ◽

Seed Treatments ◽

Naphthalic Anhydride ◽

Corn Seed ◽

Greenhouse Experiments ◽

Target Enzyme

Synergistic interaction between the insecticide terbufos and the herbicide nicosulfuron may result in severe injury to corn. Greenhouse and laboratory experiments were conducted to determine if using the imidazolinone-resistant corn ‘Pioneer-3343 IR’ (P-3343 IR) or coating corn seeds with naphthalic anhydride (NA) would reduce herbicidal injury imposed by the nicosulfuron-terbufos interaction. Greenhouse experiments showed nicosulfuron-terbufos interactions resulting in herbicidal injury in both P-3343 IR and ‘DeKalb 689’ (D-689) corn varieties, but the D-689 was more sensitive than the P-3343 IR corn. The greenhouse experiments also demonstrated protection against the nicosulfuron-terbufos interaction by NA seed treatments. Studies with radiolabeled nicosulfuron showed that terbufos inhibited the metabolism of nicosulfuron, but pretreatment of D-689 and P-3343 IR corn seed with NA decreased the inhibition in excised corn leaves. The differences in sensitivity to nicosulfuron in the two corn varieties resulted in part from the differential metabolism and primarily from the differential sensitivity of the target enzyme, acetolactate synthase, to the herbicide.

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

Weed Technology ◽

10.1017/s0890037x00026622 ◽

1990 ◽

Vol 4 (4) ◽

pp. 900-903 ◽

Cited By ~ 12

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.

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Growth and Seed Production of Horseweed (Conyza canadensis) Populations Resistant to Glyphosate, ALS-Inhibiting, and Multiple (Glyphosate + ALS-Inhibiting) Herbicides

Weed Science ◽

10.1614/ws-09-024.1 ◽

2009 ◽

Vol 57 (5) ◽

pp. 494-504 ◽

Cited By ~ 35

Author(s):

Vince M. Davis ◽

Greg R. Kruger ◽

Jeff M. Stachler ◽

Mark M. Loux ◽

William G. Johnson

Keyword(s):

Field Experiment ◽

Seed Production ◽

Acetolactate Synthase ◽

Multiple Resistance ◽

Conyza Canadensis ◽

Greenhouse Experiments ◽

Herbicide Treatments ◽

Als Inhibitors ◽

Shoot Mass ◽

Southeastern Region

Horseweed populations with mixtures of biotypes resistant to glyphosate and acetolactate synthase (ALS)–inhibiting herbicides as well as biotypes with multiple resistance to glyphosate + ALS-inhibiting herbicides have been documented in Indiana and Ohio. These biotypes are particularly problematic because ALS-inhibiting herbicides are commonly tank mixed with glyphosate to improve postemergence horseweed control in soybean. The objective of this research was to characterize the growth and seed production of horseweed populations with resistance to glyphosate or ALS-inhibiting herbicides, and multiple resistance to glyphosate + ALS-inhibiting herbicides. A four-herbicide by four-horseweed population factorial field experiment was conducted in the southeastern region of Indiana in 2007 and repeated in 2008. Four horseweed populations were collected from Indiana or Ohio and confirmed resistant to glyphosate, ALS inhibitors, both, or neither in greenhouse experiments. The four herbicide treatments were untreated, 0.84 kg ae ha−1glyphosate, 35 g ai ha−1cloransulam, and 0.84 kg ae ha−1glyphosate + 35 g ai ha−1cloransulam. Untreated plants from horseweed populations that were resistant to glyphosate, ALS-inhibiting, or multiple glyphosate + ALS-inhibiting herbicides produced similar amounts of biomass and seed compared to populations that were susceptible to those herbicides or combination of herbicides. Furthermore, aboveground shoot mass and seed production did not differ between treated and untreated plants.

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