Influence of Glyphosate-Resistant Horseweed (<i>Conyza canadensis</i>) Growth Stage on Response to Glyphosate Applications

VanGessel, Mark J.; Scott, Barbara A.; Johnson, Quintin R.; White-Hansen, Susan

doi:10.1614/wt-07-108.1

Cited by 39 publications

(45 citation statements)

References 23 publications

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“…In addition, previous studies with glufosinate indicate that its efficacy depends on both environmental conditions and weed species [29,30], while farmers often apply glufosinate after tillering and pose a further risk on its efficacy [19]. Our results are also in accordance with other recent studies [21,25]. For instance, glyphosate-resistant horseweed treated with glyphosate at three different stages of growth was more responsive at the seedling stage than at the large rosette or bolting stages.…”

Section: Dose-response Experimentssupporting

confidence: 92%

“…For the experiment on the different growth stages, regression analysis was carried out. The regression analysis used arcsine-transformed data of(percentage of the control) and natural log of glufosinate rates [25]. The data were fitted to a four parameter logistic curve (Equation: y = min + (max − min)/ 1 + (x/EC50)ˆ−Hillslope),using SigmaPlot, v.11 (Systat Software, Inc., San Jose, CA, USA).…”

Section: Discussionmentioning

confidence: 99%

“…For instance, glyphosate-resistant horseweed treated with glyphosate at three different stages of growth was more responsive at the seedling stage than at the large rosette or bolting stages. Furthermore, the survival and seed production of these potentially resistant plants due to the late treatment will probably result in an increase of the ratio of resistant plants in the accession [25]. …”

Section: Dose-response Experimentsmentioning

confidence: 99%

See 2 more Smart Citations

First Case of Glufosinate-Resistant Rigid Ryegrass (Lolium rigidum Gaud.) in Greece

et al. 2018

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Repeated applications of the same herbicide(s), which are characterized by the same mode of action, increase selection pressure, which in turn favours the evolution of herbicide-resistant weeds. Glufosinate is a broad-spectrum non-selective herbicide being used for weed control for many years around the world. Rigid ryegrass (Lolium rigidum Gaud.) is an economically important grass weed in Greece. Recent complaints by growers about control failure of rigid ryegrass with glufosinate require further investigation and have been the basis of this study. The objectives of this study were to confirm the existence of glufosinate-resistant L. rigidum in Greece and evaluate the effect of L. rigidum growth stage on glufosinate efficacy. Twenty populations of rigid ryegrass from Greece were sampled from five regions, and whole plant dose-response studies were conducted for five populations under controlled conditions with eight rates of glufosinate (0.0, 0.098, 0.187, 0.375, 0.75, 1.5, 3.0, and 6.0 kg a.i. ha −1 ). Glufosinate resistance was confirmed in three out of five populations with the level of resistance ranging from three-to seven-fold compared with the susceptible populations based on above-ground biomass reduction. Results also revealed that the level of glufosinate-resistance of rigid ryegrass was dependent on the growth stage at which it was applied.

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Section: Dose-response Experimentssupporting

confidence: 92%

Section: Discussionmentioning

confidence: 99%

Section: Dose-response Experimentsmentioning

confidence: 99%

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First Case of Glufosinate-Resistant Rigid Ryegrass (Lolium rigidum Gaud.) in Greece

et al. 2018

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“…The control of Conyza canadensis resistant to glyphosate was greater than 80% when the herbicide was applied in 10 cm high plants, whereas when the plants were treated with the herbicide at 15-20 cm height, the control did not reach 50% (Vangessel et al, 2009). …”

Section: Leaf Anatomymentioning

confidence: 90%

Evaluation of the Mechanism Responsible for the Low-Level Resistance to Glyphosate in Goosegrass

et al. 2017

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-Goosegrass (Eleusine indica) infests various crops, being reported as low-level resistant (LLR) to glyphosate. The objectives of this study were to evaluate the mechanisms of resistance to glyphosate in goosegrass by the cyt-P450 complex to identify changes in leaf anatomy of these plants and quantify the accumulation of shikimate in biotypes susceptible and with LLR. The metabolic rate was assessed by applying the cyt-P450 malathion inhibitor 30 minutes before the herbicide application. The analysis of the leaf anatomy consisted of a characterization of anatomic cross-sections and evaluation of the effect of glyphosate on the leaf epidermis and the conducting vessels. Plant tissue was collected 24 hours after treatment (HAT) of the dose-response curve to evaluate the accumulation of shikimate. The LLR biotype has not shown glyphosate metabolism by the early application of malathion due to the control of about 65% with or without applying the inhibitor. There is no anatomical evidence to determine the differential absorption of glyphosate by LLR biotypes. However, there is evidence of lower absorption and translocation of glyphosate in this biotype by lower stomatal density and a smaller diameter of the phloem. However, the LLR biotype presents diameter of phloem of 0.027 mm and stomatal density of 91.23 mm -2 , values which are below the observed ones on the susceptible biotype. The susceptible biotype presents shikimate accumulation 17% higher compared to the biotype with LLR at a dose of 1,080 g e.a. ha -1 , allowing to infer that the resistance mechanism is related to the enzyme insensitivity to the herbicide, which enables the use of appropriate management practices to control this weed.Keywords: cyt-P450 monooxygenase, shikimate, absorption and translocation, EPSPs, Eleusine indica. RESUMO -O capim-pé-de-galinha (Eleusine indica) é infestante de diversos cultivos, sendo relatado como resistente de nível baixo (RNB) ao herbicida glyphosate. Os objetivos deste trabalho foram avaliar mecanismos de resistência de capim-pé-de

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“…(Vangessel et al, 2009;Moreira et al, 2010). No momento da aplicação a temperatura média era de 28 °C; a umidade relativa, de 51%; a intensidade dos ventos, inferior a 1 km h -1 ; ausência de nuvens; e o solo encontrava-se parcialmente úmido.…”

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Estratégias de manejo de inverno e verão visando ao controle de Conyza bonariensis e Bidens pilosa

Neto¹,

Constantin

Oliveira

et al. 2010

Planta daninha

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RESUMO -Conyza bonariensis é uma das principais plantas daninhas da região Sul do País; com a seleção de biótipos tolerantes e resistentes ao herbicida glyphosate, demandas são crescentes por alternativas de manejo para essa espécie. Com esse intuito, o objetivo do presente trabalho foi avaliar a eficiência de diferentes estratégias de manejo de inverno e de verão sobre o controle de Conyza bonariensis, utilizando a mistura em tanque de glyphosate+2,4-D associada ou não com herbicidas residuais. As combinações de manejo foram realizadas após a colheita do milho safrinha (manejo de inverno), associadas a manejos antecedendo a semeadura da soja (manejo de verão), totalizando 15 tratamentos. Os manejos de inverno avaliados foram eficientes na dessecação das plantas daninhas e mantiveram excelentes níveis de controle residual até a pré-semeadura da cultura da soja. A semeadura da aveia após o manejo de inverno com posterior manejo de verão com glyphosate+2,4-D+diclosulam mostrou-se eficiente no controle de Bidens pilosa. Em todos os manejos em que o herbicida 2,4-D foi associado ao glyphosate houve controle total de Conyza bonariensis.Palavras-chave: buva, manejo entressafra, 2,4-D, resistência.ABSTRACT -Conyza bonariensis is one of the most important weeds in southern Brazil. The selection of biotypes tolerant and resistant to the herbicide glyphosate has led to increasing demand for alternatives of management strategy to control this species. This work aimed to evaluate the efficiency of different winter and summer management strategy for the control of Conyza bonariensis, by using glyphosate + 2,4-D tank mixtures combined or not with residual herbicides. The different burndown alternatives were applied after corn harvest (winter burndown), associated to applications before soybean sowing (summer burndown) with a total of 15 treatments. Winter burndown options evaluated in this research were efficient in weed desiccation and provided excellent levels of residual weed control up to the next summer soybean pre-sowing. The sowing of oats after winter burndown with subsequent summer burndown with glyphosate+diclosulam + 2,4-D was found to be efficient to control Bidens pilosa. Conyza bonariensis was totally controlled in all the burndown strategies in which the herbicide 2,4-D was associated to glyphosate.

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Influence of Glyphosate-Resistant Horseweed (Conyza canadensis) Growth Stage on Response to Glyphosate Applications

Cited by 39 publications

References 23 publications

First Case of Glufosinate-Resistant Rigid Ryegrass (Lolium rigidum Gaud.) in Greece

First Case of Glufosinate-Resistant Rigid Ryegrass (Lolium rigidum Gaud.) in Greece

Evaluation of the Mechanism Responsible for the Low-Level Resistance to Glyphosate in Goosegrass

Estratégias de manejo de inverno e verão visando ao controle de Conyza bonariensis e Bidens pilosa

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