Fluroxypyr-resistant kochia [Bassia scoparia (L.) A.J. Scott] confirmed in Alberta

Canadian Journal of Plant Science ◽

10.1139/cjps-2021-0111 ◽

2021 ◽

Author(s):

Charles M. Geddes ◽

Teandra E. Ostendorf ◽

Mallory Owen ◽

Julia Yvonne Leeson ◽

Shaun Sharpe ◽

...

Keyword(s):

Synthetic Auxin ◽

The Status ◽

Auxin Herbicides ◽

Dicamba Resistance

Recent confirmation of dicamba-resistant kochia [<i>Bassia scoparia</i> (L.) A.J. Scott] in Alberta warrants investigation of resistance to other commonly used synthetic auxin herbicides like fluroxypyr. A randomized-stratified survey of 305 sites in Alberta was conducted in 2017 to determine the status of fluroxypyr-resistant kochia. Overall, 13% of the kochia populations were fluroxypyr-resistant. Only 4% of the populations were both fluroxypyr- and dicamba-resistant, indicating that different mechanisms may confer resistance to these herbicides. When combined with estimates of dicamba resistance, about 28% of kochia populations sampled in Alberta in 2017 were resistant to at least one synthetic auxin herbicide.

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The Influence of Hard Water on 2,4-D Formulations for the Control of Dandelion

Weed Technology ◽

10.1017/wet.2020.135 ◽

2020 ◽

pp. 1-31

Author(s):

Geoffrey P. Schortgen ◽

Aaron J. Patton

Keyword(s):

Cropping Systems ◽

Hard Water ◽

Water Soluble ◽

Soluble Salt ◽

Synthetic Auxin ◽

Auxin Herbicides ◽

Acid Herbicides

The herbicide 2,4-D is used in a variety of cropping systems, especially in grasses since it is a selective postemergence broadleaf herbicide. However, the most common formulation (2,4-D dimethylamine) is antagonized when mixed in hard water. The objective of this research was to determine which formulations of 2,4-D or premixes of various formulations of synthetic auxin herbicides are subject to hard water antagonism. Formulations surveyed for hard water antagonism in the first experiment included 2,4-D dimethylamine, 2,4-D diethanolamine, 2,4-D monomethylamine, 2,4-D isopropylamine salt, 2,4-D choline salt, 2,4-D isooctyl ester, and 2,4-D ethylhexyl ester. Synthetic auxin formulation types in the second experiment included water-soluble, emulsifiable concentrates and emulsion-in-water. All formulations were mixed with both soft and hard water (600 mg CaCO3 L-1) and applied to dandelions to determine if antagonism occurred in hard water. Water-soluble (amine and choline) 2,4-D formulations were antagonized by hard water, but water-insoluble (ester) 2,4-D formulations were not antagonized. Similar results were found by formulation type with water-soluble synthetic auxin premixes antagonized but emulsifiable concentrates not antagonized. Further, water-soluble salt formulations were not antagonized when formulated in premixes with other synthetic auxin herbicides as an emulsion-in-water. This research demonstrates that all 2,4-D water-soluble formulations and water-soluble premixes with phenoxycarboxylic acid herbicides are subject to hard water antagonism. Formulations of 2,4-D containing emulsifying agents protect against antagonism by the water-insoluble nature of ingredients in their formulation.

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Weed Control with Halauxifen-Methyl Applied Alone and in Mixtures with 2,4-D, Dicamba, and Glyphosate

Weed Technology ◽

10.1017/wet.2018.48 ◽

2018 ◽

Vol 32 (5) ◽

pp. 597-602 ◽

Cited By ~ 7

Author(s):

Marcelo Zimmer ◽

Bryan G. Young ◽

William G. Johnson

Keyword(s):

Weed Control ◽

Field Experiments ◽

Common Ragweed ◽

Synthetic Auxin ◽

Redroot Pigweed ◽

Giant Ragweed ◽

Auxin Herbicides ◽

Control Spectrum

AbstractSynthetic auxin herbicides such as 2,4-D and dicamba are often utilized to control broadleaf weeds in preplant burndown applications to soybean. Halauxifen-methyl is a new synthetic auxin herbicide for broadleaf weed control in preplant burndown applications to corn, cotton, and soybean at low use rates (5 g ae ha–1). Field experiments were conducted to evaluate efficacy and weed control spectrum of halauxifen-methyl applied alone and in mixtures with 2,4-D (560 g ae ha–1), dicamba (280 g ae ha–1), and glyphosate (560 g ae ha–1). Glyphosate-resistant (GR) horseweed was controlled with halauxifen-methyl applied alone (90% control) and in mixtures (87% to 97% control) 35 d after treatment (DAT). Common ragweed was controlled 93% with halauxifen-methyl applied alone and 91% to 97% in mixtures 35 DAT. Halauxifen-methyl applied alone resulted in poor giant ragweed control 21 DAT (73% control); however, mixtures of halauxifen-methyl with 2,4-D, dicamba, or glyphosate controlled giant ragweed (86% to 98% control). Halauxifen-methyl alone resulted in poor redroot pigweed control (62% control) 21 DAT; however, mixtures of halauxifen-methyl with dicamba, 2,4-D, or glyphosate controlled redroot pigweed (89% to 98% control). Halauxifen-methyl controls GR horseweed and common ragweed applied alone and in mixtures with other synthetic auxin herbicides and glyphosate. Furthermore, mixing 2,4-D or dicamba with halauxifen-methyl can increase the weed control spectrum in preplant burndown applications.

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Creeping Bellflower Response to Glyphosate and Synthetic Auxin Herbicides

HortTechnology ◽

10.21273/horttech03853-17 ◽

2018 ◽

Vol 28 (1) ◽

pp. 6-9

Author(s):

Carl W. Coburn ◽

Albert T. Adjesiwor ◽

Andrew R. Kniss

Keyword(s):

The Other ◽

Residential Areas ◽

Synthetic Auxin ◽

Auxin Herbicides ◽

Postemergence Herbicides ◽

Biomass Reduction

Creeping bellflower (Campanula rapunculoides) is a difficult to manage weed commonly found in turfgrass and residential areas. We evaluated the efficacy of selected postemergence herbicides (glyphosate, dicamba, clopyralid, quinclorac, and triclopyr) on greenhouse-grown creeping bellflower. The experiment was conducted in Jan. 2016 and repeated in Sept. 2016. Each herbicide was applied at five rates plus a nontreated control. Clopyralid caused greater creeping bellflower biomass reduction and mortality than the other herbicides investigated. The herbicide dose required to cause 50% mortality was lowest for clopyralid [86–138 g·ha−1 acid equivalent (a.e.)] compared with dicamba (221–536 g·ha−1 a.e.), glyphosate (196–678 g·ha−1 a.e.), triclopyr (236–782 g·ha−1 a.e.), and quinclorac (>3000 g·ha−1 a.e.). Clopyralid could be an effective herbicide for managing creeping bellflower, although it is currently not registered for use in many habitats where this plant is a problematic weed.

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Herbicides for Postemergence Control of Mile-a-Minute (Mikania micrantha)

Invasive Plant Science and Management ◽

10.1614/ipsm-d-13-00069.1 ◽

2014 ◽

Vol 7 (2) ◽

pp. 303-309 ◽

Cited By ~ 4

Author(s):

Brent A. Sellers ◽

Sarah R. Lancaster ◽

Kenneth A. Langeland

Keyword(s):

Dose Response ◽

South Florida ◽

Growth Reduction ◽

Mikania Micrantha ◽

Synthetic Auxin ◽

Greenhouse Experiments ◽

Auxin Herbicides ◽

Dose Response Study

AbstractGreenhouse experiments were conducted to evaluate mile-a-minute response to selected herbicides. In the first experiment, mile-a-minute response was evaluated following the application of aminocyclopyrachlor, aminopyralid, fluroxypyr, glufosinate, glyphosate, imazamox, imazapic, metsulfuron, penoxsulam, and triclopyr. Applications of aminocyclopyrachlor, aminopyralid, fluroxypyr, glufosinate, glyphosate, and triclopyr all resulted in mile-a-minute control 70% or greater 8 wk after treatment (WAT). Mile-a-minute sensitivity to these six herbicides was further evaluated in a dose-response study. Although 90% growth reduction (GR90) values were determined for aminopyralid and glyphosate, statistically significant results were not obtained for aminocyclopyrachlor, fluroxypyr, glufosinate, and triclopyr. The results of these experiments suggest that glyphosate, as well as the synthetic auxin herbicides aminocyclopyrachlor, aminopyralid, fluroxypyr, and triclopyr, should be further evaluated for mile-a-minute control in south Florida.

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Triple-resistant kochia [Kochia scoparia (L.) Schrad.] in Alberta

Canadian Journal of Plant Science ◽

10.1139/cjps-2018-0256 ◽

2019 ◽

Vol 99 (2) ◽

pp. 281-285 ◽

Cited By ~ 7

Author(s):

Hugh J. Beckie ◽

Linda M. Hall ◽

Scott W. Shirriff ◽

Elise Martin ◽

Julia Y. Leeson

Keyword(s):

Mode Of Action ◽

Acetolactate Synthase ◽

Kochia Scoparia ◽

Synthetic Auxin ◽

Als Inhibitor ◽

Dicamba Resistance

A randomized stratified survey was conducted in Alberta in 2017 to determine the distribution and abundance of multiple-resistant [acetolactate synthase (ALS) inhibitor, glycine, and synthetic auxin] kochia. All populations were ALS inhibitor resistant, with glyphosate and dicamba resistance confirmed in 50% and 18% of populations, respectively. Ten percent of populations exhibited resistance to all three mode-of-action herbicides.

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Anatomical Response of St. Augustinegrass to Aminocyclopyrachlor Treatment

Weed Science ◽

10.1614/ws-d-10-00116.1 ◽

2011 ◽

Vol 59 (2) ◽

pp. 263-269 ◽

Cited By ~ 7

Author(s):

Michael L. Flessner ◽

Roland R. Dute ◽

J. Scott McElroy

Keyword(s):

Apical Meristem ◽

Vascular Tissue ◽

Growth Stimulation ◽

Adventitious Root Formation ◽

Root Tip ◽

Synthetic Auxin ◽

Tissue Proliferation ◽

Vascular Parenchyma ◽

Affected Tissue ◽

Auxin Herbicides

Aminocyclopyrachlor (AMCP) is a synthetic auxin herbicide that controls primarily broadleaf (eudicotyledonous) weeds. Previous research indicates that St. Augustinegrass is unacceptably injured by AMCP. In light of the fact that synthetic auxin herbicides usually are safe when applied to monocotyledons, the mechanism for this injury is not fully understood. Anatomical response of St. Augustinegrass to AMCP was investigated using light microscopy. Apical meristem node tissue responded with callus tissue proliferation, abnormal location and development of the apical meristem, necrosis of the developing vascular tissue, vascular parenchyma proliferation, and xylem gum blockages. Node tissues away from the apical meristem responded with xylem gum blockages and the stimulation of lateral meristems and adventitious root formation. Root tip response to AMCP treatment was characterized by a loss of organization. Root tip apical meristem and vascular tissue maturation was disorganized. Additionally, lateral root generation occurred abnormally close to the root tip. These responses impair affected tissue functionality. Mature tissue was unaffected by AMCP treatment. All of these responses are characteristic of synthetic auxin herbicide treatment to other susceptible species. This research indicates that AMCP treatment results in St. Augustinegrass injury and subsequent death through deleterious growth stimulation and concomitant vascular inhibition.

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2,4-D–Resistant Buckhorn Plantain (Plantago lanceolata) in Managed Turf

Weed Technology ◽

10.1017/wet.2017.98 ◽

2018 ◽

Vol 32 (2) ◽

pp. 182-189 ◽

Cited By ~ 9

Author(s):

Aaron J. Patton ◽

Daniel V. Weisenberger ◽

Geoff P. Schortgen

Keyword(s):

Dose Response ◽

Plantago Lanceolata ◽

Resistance Mechanism ◽

Cross Resistance ◽

Pyridinecarboxylic Acid ◽

First Report ◽

Synthetic Auxin ◽

Group 4 ◽

Auxin Herbicides ◽

Acid Herbicides

AbstractA population of buckhorn plantain with suspected resistance to 2,4-D was identified in central Indiana following 30 yr of 2,4-D–containing herbicide applications. Our objectives were to (1) confirm and quantify the level of herbicide resistance in the buckhorn plantain population using dose–response experiments and (2) find alternative herbicides that could be used to control this population. Greenhouse experiments were conducted to quantify the dose–response of resistant (R) and susceptible (S) biotypes of buckhorn plantain to both 2,4-D and triclopyr, two synthetic auxin herbicides from different chemical families. The R biotype was ≥6.2 times less sensitive to 2,4-D than the S biotype. The efficacy of triclopyr was similar on both the R and S biotypes of buckhorn plantain, suggesting the absence of cross-resistance to this herbicide. This is the first report of 2,4-D resistance in buckhorn plantain and the first report of 2,4-D resistance in turf. The resistance mechanism was limited to within a chemical family (phenoxycarboxylic acid) and did not occur across all WSSA Group 4 synthetic auxin herbicides, as the pyridinecarboxylic acid herbicides clopyralid and triclopyr and the arylpicolinate herbicide halauxifen-methyl provided control in our experiments.

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Influence of Application Timings and Sublethal Rates of Synthetic Auxin Herbicides on Soybean

Weed Technology ◽

10.1614/wt-d-13-00145.1 ◽

2014 ◽

Vol 28 (3) ◽

pp. 454-464 ◽

Cited By ~ 26

Author(s):

Craig B. Solomon ◽

Kevin W. Bradley

Keyword(s):

Yield Components ◽

Seed Weight ◽

Yield Loss ◽

Field Trials ◽

Synthetic Auxin ◽

Stages Of Growth ◽

General Order ◽

Auxin Herbicides ◽

Production Areas ◽

Near Future

Synthetic auxin herbicides have long been utilized for the selective control of broadleaf weeds in a variety of crop and noncrop environments. Recently, two agrochemical companies have begun to develop soybean with resistance to 2,4-D and dicamba which might lead to an increase in the application of these herbicides in soybean production areas in the near future. Additionally, little research has been published pertaining to the effects of a newly-discovered synthetic auxin herbicide, aminocyclopyrachlor, on soybean phytotoxicity. Two field trials were conducted in 2011 and 2012 to evaluate the effects of sublethal rates of 2,4-D amine, aminocyclopyrachlor, aminopyralid, clopyralid, dicamba, fluroxypyr, picloram, and triclopyr on visible estimates of soybean injury, height reduction, maturity, yield, and yield components. Each of these herbicides was applied to soybean at the V3 and R2 stages of growth at 0.028, 0.28, 2.8, and 28 g ae ha−1. Greater height reductions occurred with all herbicides, except 2,4-D amine and triclopyr when applied at the V3 compared to the R2 stage of growth. Greater soybean yield loss occurred with all herbicides except 2,4-D amine when applied at the R2 compared to the V3 stage of growth. The only herbicide applied that resulted in no yield loss at either stage was 2,4-D amine. When applied at 28 g ae ha−1at the V3 stage of growth, the general order of herbicide-induced yield reductions to soybean from greatest to least was aminopyralid > aminocyclopyrachlor = clopyralid = picloram > fluroxypyr > triclopyr > dicamba > 2,4-D amine. At the R2 stage of growth, the general order of herbicide-induced yield reductions from greatest to least was aminopyralid > aminocyclopyrachlor = picloram > clopyralid > dicamba > fluroxypyr = triclopyr > 2,4-D amine. Yield reductions appeared to be more correlated with seeds per pod than to pods per plant and seed weight. An 18- to 26-d delay in soybean maturity also occurred with R2 applications of all synthetic auxin herbicides at 28 g ae ha−1except 2,4-D. Results from this research indicate that there are vast differences in the relative phytotoxicity of these synthetic auxin herbicides to soybean, and that the timing of the synthetic auxin herbicide exposure will have a significant impact on the severity of soybean height and/or yield reductions.

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Efficacy of triclopyr and synthetic auxin herbicide mixtures for common blue violet (Viola sororia) control

Weed Technology ◽

10.1017/wet.2020.50 ◽

2020 ◽

Vol 34 (4) ◽

pp. 475-481

Author(s):

Aaron J. Patton ◽

Daniel V. Weisenberger ◽

Wenwen Liu

Keyword(s):

Data Collection ◽

Chlorophyll Content ◽

Dose Response ◽

Dry Weight ◽

Synthetic Auxin ◽

Comparison Experiment ◽

Herbicide Mixtures ◽

Auxin Herbicides ◽

High Label

AbstractCommon blue violet is a widely distributed, perennial broadleaf that is difficult to control in lawns. Two experiments were conducted to evaluate the efficacy of synthetic auxin herbicides and their mixtures or rate for common blue violet control. A herbicide comparison experiment was conducted with treatments including a nontreated check; 2,4-D dimethylamine; 2,4-D isooctyl ester (2,4-D ester); dichlorprop (2,4-DP) ethylhexyl ester, MCPA dimethylamine; mecoprop dimethylamine; triclopyr butoxyethyl ester; quinclorac; and mixtures of triclopyr + quinclorac; 2,4-D ester + 2,4-DP; 2,4-D ester + triclopyr; 2,4-D ester + 2,4-DP + triclopyr. All herbicides were applied at 1.12 kg ae ha−1 except quinclorac (0.84 kg ha−1). Additionally, a triclopyr dose-response experiment was conducted using rates of 0, 0.14, 0.28, 0.56, 0.84, and 1.12 kg ha−1. Epinasty ranged from 80% to 99% at 21 d after application for triclopyr-containing treatments and no more than 28% for all other treatments. Plant mass from harvest and regrowth data from the comparison experiment indicated triclopyr-containing treatments provided the highest common blue violet control. Mixtures containing triclopyr did not differ from triclopyr alone, indicating there was no added effect between herbicide mixtures. The triclopyr dose-response experiment confirmed triclopyr efficacy across data collection types. As triclopyr dose increased, violet epinasty increased and chlorophyll content and dry weight decreased. Triclopyr applied at 0.81 kg ha−1 or greater concentration provided 75% or greater control, as indicated by regrowth data. Many herbicides containing triclopyr are registered for use in turf, but most apply a concentration not greater than 0.56 kg ha−1 triclopyr when applied at the high label rate. Thus, to achieve good (75%) common blue violet control, turf managers should select products that contain triclopyr and apply doses of at least 0.81 kg ha−1 when used according to the label.

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