Glyphosate Applied at the Early Reproductive Stage Impairs Seed Production of Glyphosate-Resistant Hairy Fleabane (original) (raw)
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Glyphosate Resistance Affect the Physiological Quality of Conyza bonariensis seeds
Planta Daninha, 2019
ABSTRACT: High seed production and dispersal capacity and glyphosate resistance are among the main factors that have made hairy fleabane (Conyza bonariensis) one of the most important and dispersed weeds in the world. Herbicide-resistant weeds populations may have fitness cost due to molecular, physiological, and biochemical changes. This study aimed to evaluate the physiological quality of seeds of Conyza spp. and determine whether glyphosate resistance causes fitness costs for resistant biotypes. Seeds from six hairy fleabane biotypes, three glyphosate-resistant and three -sensitive, with a resistance factor average of 11.7 were studied. Among the studied biotypes, five were identified as C. bonariensis and one as C. blakei. Seed analyses were performed in a completely randomized design with ten replications of 100 seeds each (1,000 seeds per biotype). The analyzed seeds were originated from second-generation self-pollinating plants with known segregation rate. The mean results in...
2016
Flaxleaf fleabane (Conyza bonariensis (L.) Cronquist) has been considered a major weed in dryland cropping systems in Australia. Resistance in populations of C. bonariensis to glyphosate has also been confirmed. The weed is very difficult to control with any single herbicide application especially when herbicides are applied after the bolting stage. Anecdotal evidence suggests that some chemicals might affect fleabane seed viability and/or dormancy based on the observations that seeds collected from certain paddocks did not germinate. Glasshouse experiments were conducted to investigate whether applications of glyphosate and paraquat could sterilise the weed seeds and affect seed dormancy of fleabane. Results showed that both herbicides affected the seed viability and dormancy, depending on the application timing and the herbicide. The herbicide-induced dormancy decreased during storage under laboratory conditions.
Glyphosate-resistant hairy fleabane (Conyza bonariensis) in Spain
Weed Technology, 2007
Overreliance on glyphosate can increase the risks of reduced efficacy of the herbicide on weeds and weed resistance, even in regions without glyphosate-resistant crops. That is the reality in Greece, with frequent reports of reduced efficacy of glyphosate against increasingly problematic weeds, such as Conyza spp. The objectives of this study were to determine the occurrence of glyphosate resistance in hairy fleabane populations in central and southern Greece and the effect of weed growth stage on glyphosate efficacy under controlled environmental conditions and to evaluate alternative herbicides in field trials for control of glyphosate-resistant and -susceptible hairy fleabane. Plants from 60 accessions of hairy fleabane, sampled from five prefectures in Greece, were sprayed with glyphosate at 0.36 kg ae ha 21 ; 15 were classified as potentially resistant. After initial screening, 15 potentially susceptible or resistant accessions were selected and dose-response experiments were conducted. Glyphosate rates required to control some accessions were four to seven times greater than that for control of the reference susceptible accession, AR4. Sensitivity of a resistant hairy fleabane accession to glyphosate was strongly dependent on growth stage, with plants at the seedling stage being most sensitive to the herbicide. A field trial indicated that diquat, glufosinate, or glufosinate + oxyfluorfen controlled glyphosate-resistant or -susceptible hairy fleabane. These herbicides, along with various integrated management strategies, have good potential to manage or slow the spread of glyphosate resistance in this species. Nomenclature: Diquat; glufosinate; glyphosate; oxyfluorfen; hairy fleabane, Conyza bonariensis (L.) Cronq. ERIBO.
Resistance of flaxleaf fleabane (Conyza bonariensis (L.) Cronquist) to glyphosate
Bulletin of the National Research Centre, 2020
Resistance to glyphosate has been reported in flaxleaf fleabane populations within a number of grain growing areas in southern Queensland and northern New South Wales and other cropping regions across Australia. To investigate the processes contributing to the evolution and spread of glyphosate-resistant flaxleaf fleabane, the resistant populations tested in dose-response experiments varied in their responses to glyphosate from two to eight times the recommended rate. The different dose responses obtained may indicate different mechanisms of resistance. This can possibly be attributed to an independent evolution of resistance. The results demonstrate that glyphosate resistance is widespread across Australia and has likely evolved multiple times as well as dispersing by seeds.
Canadian Journal of Plant Science, 2014
2014. Canada fleabane (Conyza canadensis) control with preplant applied residual herbicides followed by 2,4-D choline/glyphosate DMA applied postemergence in corn. Can. J. Plant Sci. 94: 1231Á1237. Glyphosate resistant (GR) Canada fleabane (Conyza canadensis) is an extremely problematic weed in no-tillage farming operations. A total of five field trials were conducted over a 2-yr (2012 and 2013) period in Ontario to determine the level of GR Canada fleabane control with a two-pass weed control program of a pre plant (PP) residual herbicide followed by 2,4-D choline/glyphosate dimethylamine (DMA) applied POST. Among residual herbicide treatments evaluated, s-metolachlor (1600 g a.i. ha (1 )'flumetsulam (50 g a.i. ha (1 )'clopyralid (135 g a.e. ha (1 ) provided the most consistent (95Á99%) control across all sites 8 wk after application (WAA). S-metolachlor/atrazine (1800 g a.i. ha (1 ) did not provide effective GR Canada fleabane control (21Á86%) 8 WAA. The preplant residual herbicides followed by 2,4-D choline/glyphosate DMA (1720 g a.e. ha (1 ) POST provided 97Á100% control. Glyphosate (900 g a.e. ha (1 ) applied PP followed by 2,4-D choline/glyphosate DMA POST provided 80Á93% control 8 WAA. The application of 2,4-D choline/glyphosate DMA POST following any PP residual herbicide resulted in 97% or greater control of GR Canada fleabane. Results from this research demonstrate that residual herbicides applied PP followed by 2,4-D choline/glyphosate DMA POST provides excellent control of GR Canada fleabane, and also incorporates different modes of action thereby limiting the selection of resistant weeds. A. et Sikkema, P. H. 2014. Lutte contre la vergerette du Canada (Conyza canadensis) chez le maı¨s par application d'herbicides re´siduels avant la plantation puis de 2,4-D choline/ glyphosate DMA apre`s la levee. Can. J. Plant Sci. 94: 1231Á1237. La vergerette du Canada (Conyza canadensis) re´sistante au glyphosate (RG) s'ave`re extreˆmement proble´matique sur les terres agricoles qui ne sont pas travaille´es. Les auteurs ont effectue´cinq essais sur le terrain pendant deux ans (2012 et 2013), en Ontario, en vue d'e´tablir dans quelle mesure on pourrait lutter contre la vergerette du Canada RG avec un programme de de´sherbage en deux temps, a`savoir l'application d'un herbicide re´siduel de pre´plantation et l'application de 2,4-D choline/glyphosate DMA post-leve´e. Au nombre des herbicides re´siduels teste´s, le me´lange s-me´tolachlor (1600 g de matie`re active par hectare)'flumetsulam (50 g m.a. par hectare)'clopyralid (135 g m.a. par hectare) a donne´le taux de de´sherbage le plus stable (95Á99 %) aux diffe´rents sites, huit semaines apre`s application. Le s-me´tolachlor/atrazine (1800 g m.a. par hectare) ne combat pas efficacement l'adventice (21Á86 %), huit semaines apre`s application. L'application d'herbicides re´siduels avant la plantation suivie d'une application post-leve´e de 2,4-D choline/glyphosate DMA (1720 g m.a. par hectare) de´truit de 97 a`100 % de la vergerette RG. L'application de glyphosate (900 g m.a. par hectare) apre`s la plantation puis de 2,4-D choline/glyphosate DMA apre`s la leve´e de´truit de 80 a`93 % de l'adventice, huit semaines apre`s application. L'application de 2,4-D choline/glyphosate DMA apre`s la leve´e conse´cutivement a`celle d'un herbicide re´siduel quelconque avant la plantation tue 97 % ou plus de l'adventice. Ces re´sultats montrent que l'application d'herbicides re´siduels avant la plantation puis de 2,4-D choline/ glyphosate DMA apre`s la leve´e assure une excellente lutte contre la vergerette du Canada RG. Parce qu'ils agissent diffe´remment, ces herbicides concourent aussi a`retarder l'apparition d'adventices re´sistantes.
Control of glyphosate resistant hairy fleabane (Conyza bonariensis) with dicamba and 2,4-D
Planta Daninha, 2012
Auxyn type herbicides such as dicamba and 2,4-D are alternative herbicides that can be used to control glyphosate-resistant hairy fleabane. With the forthcoming possibility of releasing dicamba-resistant and 2,4-D-resistant crops, use of these growth regulator herbicides will likely be an alternative that can be applied to the control of glyphosate resistant hairy fleabane (Conyza bonariensis). The objective of this research was to model the efficacy, through dose-response curves, of glyphosate, 2,4-D, isolated dicamba and glyphosatedicamba combinations to control a brazilian hairy fleabane population resistant to glyphosate. The greenhouse dose-response studies were conducted as a completely randomized experimental design, and the rates used for dose response curve construction were 0, 120, 240, 480, 720 and 960 g a.i. ha-1 for 2,4-D, dicamba and the dicamba combination, with glyphosate at 540 g a.e. ha-1. The rates for glyphosate alone were 0, 180, 360, 540, 720 and 960 g a.e. ha-...
Low temperature reverses the resistance to glyphosate in hairy fleabane ( Conyza bonariensis )
Journal of Plant Protection Research, 2020
Environmental factors and the addition of adjuvants to the spray tank mix may interfere with glyphosate efficiency in hairy fleabane control. The objective of this study was to evaluate the effect of air temperature and the addition of ammonium sulfate (NH4)2SO4 to glyphosate in the control of glyphosate-resistant (GR) and -susceptible (GS) hairy fleabane. Treatments consisted of air temperatures of 12°C and 25°C, six doses of glyphosate from zero to 2,880 g · ha−1, the presence or absence of (NH4)2SO4 in the spray solution, and one GS and another GR biotype. At the lowest tested dose (180 g · ha−1), control of the GR biotype was 91% and 20% when the plants were kept at 12°C and 25°C, respectively, reducing the resistance factor (RF) by 9.30 times and was associated to the reduction of temperature. The addition of (NH4)2SO4 increased the control by 10−20% at high glyphosate doses and at 25°C. The resistance of hairy fleabane to glyphosate was completely reversed when the plants were...
Sumatran Fleabane (Conyza sumatrensis) Resistance to Glyphosate in Peach Orchards in Turkey
HortScience
Glyphosate has been widely used to control annual, perennial, and biennial weeds including Conyza species. Conyza sumatrensis (Sumatran fleabane) is considered a highly invasive and troublesome weed worldwide, including in European and Mediterranean regions. In Turkey, the use of glyphosate in orchards has recently increased; however, extensive use of glyphosate has resulted in poor control of C. sumatrensis in several peach orchards. The objectives of this research were to determine if C. sumatrensis is resistant to glyphosate and identify alternative herbicides with different modes of action that can be used instead of glyphosate. Two dose response studies were conducted in the greenhouse to evaluate the response of four C. sumatrensis populations to glyphosate, chlorsulfuron, and metribuzin. Glyphosate isopropyl amine and glyphosate potassium was applied at 0, 0.25, 0.5, 1, 2, 4, and 8 times the use rate of 1080 g a.e./ha (a.e. indicates acid equivalent) when the plants were at r...
Seedbank and Field Emergence of Weeds in Glyphosate-Resistant Cropping Systems in the United States
Weed Science, 2015
A segment of the debate surrounding the commercialization and use of glyphosateresistant (GR) crops focuses on the theory that the implementation of these traits is an extension of the intensification of agriculture that will further erode the biodiversity of agricultural landscapes. A large field-scale study was initiated in 2006 in the U.S. on 156 different field sites with a minimum 3-yr history of GR-corn, -cotton or -soybean in the cropping system. The impact of cropping system, crop rotation, frequency of using the GR crop trait, and several categorical variables on seedbank weed population density and diversity was analyzed. The parameters of total weed population density of all species in the seedbank, species richness, Shannon's H' and evenness were not affected by any management treatment. The similarity between the seedbank and aboveground weed community was more strongly related to location than management; previous year's crops and cropping systems were also important while GR trait rotation was not. The composition of the weed flora was more strongly related to location (geography) than any other parameter. The diversity of weed flora in agricultural sites with a history of GR crop production can be influenced by several factors relating to the specific method in which the GR trait is integrated (cropping A segment of the debate surrounding the commercialization and use of glyphosate-resistant (GR) 23 crops focuses on the theory that the implementation of these traits is an extension of the 24 intensification of agriculture that will further erode the biodiversity of agricultural landscapes. A 25 Manuscript Click here to download Manuscript: Seedbankpaper_Rev2 10-30-14.docx