Influence of Herbicides on Competition Weed and Glyphosate-resistant Soybean

Competitions of light,nutrient and water between transgenic glyphosate resistant soybean and weed were evaluated with different herbicides(glyphosate,acetochlor,and the mixture of fomesafen and quizalofop-p-ethyl)in filed,which displayed that the application of the mixture of fomesafen and quizalofop-p-ethyl on soybeans had the best anti-herbicidal effect while glyphosate had the weakest effect.The half-life extended by herbicide mixture would affect the soil nutrients.Weed-soybean competitions affected the absorption of nutrients on soybean and yield.However,effective control of weeds could significantly reduce the weed density,improve the field through different layers of light transmittance and the absorption of nutrients on soybean,and enhance the comprehensive competitiveness of soybean.

Control of Glyphosate and Acetolactate Synthase Resistant Common Ragweed (Ambrosia artemisiifolia L.) in Soybean (Glycine max L.) with Preplant Herbicides

A population of common ragweed in Ontario was confirmed to be resistant to glyphosate in 2011. Group 2 [acetolactate synthase (ALS) inhibitors] resistant common ragweed was first confirmed in Ontario in 2000. Previously, glyphosate provided excellent control of common ragweed in glyphosate resistant soybean but with the confirmation of glyphosate resistant (GR) common ragweed, alternative herbicides need to be evaluated. Eight field trials with preplant herbicides were completed over two years (2013 and 2014) in fields with confirmed GR common ragweed. Tank-mixes of glyphosate and linuron or metribuzin provided 88% - 99% and 86% - 98% control 4 weeks after application (WAA) and 80% - 92% and 80% - 95% control 8 WAA, respectively. However, these herbicides also had among the highest environmental impact of the herbicides tested. Based on the results of these studies, GR common ragweed can be controlled with residual herbicides when applied preemergence in soybean. Currently, there are no post emergence herbicides that provide adequate control of GR common ragweed, therefore, preemergence herbicides with residual are essential for full season control.

Interaction of the Bioherbicide <i>Myrothecium verrucaria</i>with Technical-Grade Glyphosate on Glyphosate-Susceptible and -Resistant Palmer Amaranth

Previously we found that a strain of Myrothecium verrucaria (MV) exhibited bioherbicidal activity against several important weeds, and that some commercial formulations of glyphosate applied with MV resulted in synergistic interactions that improved weed control efficacy. We also found that MV had bioherbicidal activity against glyphosate-resistant Palmer amaranth. We have also reported that some commercial formulations are inhibitory to MV. Our objectives were to test the effect of unformulated glyphosate (high purity, technical-grade glyphosate) alone and in combination with MV for bioherbicidal activity on glyphosate-susceptible and -resistant Palmer amaranth biotypes under greenhouse conditions and to examine technical-grade glyphosate on the growth of this bioherbicide. High purity glyphosate (without adjuvants/surfactants) was not toxic to MV growth and sporulation at concentrations up to 2.0 mM when grown on agar supplemented with the herbicide. Both biotypes were injured by MV and MV plus glyphosate treatments as early as 19 h after application (3 h after a dew period of 16 h). These injury effects increased and were more evident through the 6-day time course, when after 120 h the MV plus glyphosate treatment had killed all glyphosate-susceptible and -resistant plants. The interaction of glyphosate plus MV was synergistic toward the control of Palmer amaranth. Data strongly suggest that the active ingredient is responsible for the synergy previously found when this bioherbicide was combined with some commercial formulations of glyphosate. Results demonstrated that MV can control both glyphosate-resistant and -susceptible Palmer amaranth seedlings and act synergistically with high-purity glyphosate to provide improved weed control.

Efficacy of POST glyphosate applications in combination with other POST herbicides in glyphosate-resistant corn (Zea mays L.)

The use of glyphosate-resistant corn has facilitated a shift from a reliance on preemergence residual herbicides to postemergence (POST) herbicides, and in some cases exclusively glyphosate. Glyphosate is a non-selective herbicide that is relatively slow-acting, which may allow weeds to continue to compete with corn after application and potentially decrease crop yield. The addition of several POST corn herbicides, with some residual control, to an early-season glyphosate application was examined to determine if the tankmix combination would improve the speed of weed control compared to glyphosate applied alone. Seven field trials were conducted over three years (2009, 2010 and 2011) near Ridgetown and Exeter, Ontario. The control of common ragweed was improved 3 days after application (DAA) with three POST glyphosate tankmixes compared to glyphosate alone. However control was still less than 55%. Depending on the weed species examined, at 28 DAA two of the glyphosate tankmix treatments tested provided better common ragweed, common lambsquarters, or green foxtail control than glyphosate alone. Treatments providing better weed control at 28 DAA also typically decreased weed density compared to glyphosate alone.

Weed and insect control affected by mixing insecticides with glyphosate in cotton

Field studies were conducted in 2012 and 2013 to evaluate weed and insect control efficacy with glyphosate at 1 230 g ai（active ingredient） ha^（-1） and the insecticides acephate（728 g ai ha^（-1））,carbosulfan（135 g ai ha^（-1））,endosulfan（683 g ai ha^（-1））,imidacloprid（32 g ai ha^（-1））,or lambda-cyhalothrin（23 g ai ha^（-1））,as well as glyphosate tank-mixed with these insecticides.Four of the most common weeds in cotton,common purslane,false daisy,goosegrass,and lambsquarters,were manually sown in the cotton field and treated with glyphosate alone or in combination with insecticides.Glyphosate efficacy,based on visual estimates of control and weed fresh weight at 21 d after treatment（DAT）,was unaffected by the addition of insecticides.Four weeds were controlled by 93-97%and 86-100%（visual rating） and reduced weed fresh biomass by98-99%and 96-100%with glyphosate alone and its combination with insecticides,respectively.Addition of glyphosate to acephate improved cotton aphid control compared with acephate alone.However,addition of glyphosate to carbosulfan,endosulfan,imidacloprid,or lambda-cyhalothrin did not affect the aphid control when compared with the insecticide alone treatments.These results indicate that cotton producers could potentially integrate weed and insect management strategies by choosing suitable insecticide mixing partners with glyphosate,thereby reducing the application costs without sacrificing the efficacy of the glyphosate or the insecticides.

Activity of Isoxaflutole plus Metribuzin Tankmixes in Isoxaflutole-Resistant Soybean

Isoxaflutole-resistant soybean is currently in development for commercialization in North America. Proposals to use isoxaflutole + metribuzin as the main herbicide tank-mixture raise concerns as there is limited grass control with these herbicides. Strategies are needed to improve grass control with isoxaflutole + metribuzin. Nine experiments were conducted over a two-year period (2017, 2018) to determine the efficacy of isoxaflutole + metribuzin (52.5 + 210 g a·i· ha-1) applied alone and co-applied with pendimethalin, dimethenamid-P, pethoxamid, pyroxasulfone or S-metolachlor applied preemergence (PRE). Comparisons were made with isoxaflutole + metribuzin at a low rate (52.5 + 210 g a·i· ha-1), medium rate (79 + 315 g a·i· ha-1) and a high rate (105 + 420 g a·i· ha-1). Eight weed species were evaluated including common lambsquarters, green and redroot pigweed, common ragweed, velvetleaf, green and giant foxtail, yellow foxtail, barnyardgrass and witchgrass. All herbicides were affected by amount of rainfall following application;less rainfall resulted in reduced weed control. The addition of pendimethalin, dimethenamid-P, pethoxamid, pyroxasulfone or S-metolachlor to the low rate ofisoxaflutole + metribuzin provided equivalent control of all weed species evaluated compared toisoxaflutole + metribuzin at the low, medium, or high rate.

Bioassay and Characterization of Several Palmer Amaranth (<i>Amaranthus palmeri</i>) Biotypes with Varying Tolerances to Glyphosate

The wide distribution of Palmer amaranth (Amaranthus palmeri) in the southern US became a serious weed control problem prior to the extensive use of glyphosate-resistant crops. Currently glyphosate-resistant populations of Palmer amaranth occur in many areas of this geographic region creating an even more serious threat to crop production. Investigations were undertaken using four biotypes (one glyphosate-sensitive, one resistant from Georgia and two of unknown tolerance from Mississippi) of Palmer amaranth to assess bioassay techniques for the rapid detection and level of resistance in populations of this weed. These plants were characterized with respect to chlorophyll, betalain, and protein levels and immunological responses to an antibody of 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) the target site of glyphosate. Only slight differences were found in four biotypes grown under greenhouse conditions regarding extractable soluble protein and chlorophyll content, but one biotype was found to be devoid of the red pigment, betalain. Measurement of early growth (seedling shoot elongation) of seedlings was a useful detection tool to determine glyphosate resistance. A leaf disc bioassay (using visual ratings and/or chlorophyll analysis) and an assay for shikimate accumulation were effective methods for determining herbicide resistance levels. The two unknown biotypes were found to be resistant to this herbicide. Some differences were found in the protein profiles of the biotypes, and western blots demonstrated a weak labeling of antibody in the glyphosate-sensitive biotype, whereas strong labeling occurred in the resistant plants. This latter point supports research by others, that increased copy number of the EPSPS gene (and increased EPSPS protein levels) is the resistance mechanism in this species. Results indicate the utility of certain bioassays for the determination of resistance and provide useful comparative information on the levels of inherent constituents among closely related plants.

转基因大豆SHZD32-01对草甘膦的抗性及草甘膦除草效果研究

为了评价自主研制的转G10-EPSPS基因的抗除草剂转基因大豆SHZD32-01对不同浓度草甘膦的耐受性和草甘膦的除草效果,以SHZD32-01大豆为试验材料,以受体中豆32为对照,采用随机区组设计,在V3期喷施田间剂量为1,2,4倍浓度的草甘膦(1.23,2.46,4.92 kg·hm^(-2))和清水,统计大豆株高和受害率等指标,以及草甘膦喷施后各小区再次长出杂草的密度与高度。结果表明:1~4倍田间浓度的草甘膦处理下,转基因大豆SHZD32-01的株高和覆盖度之间无显著差异,对转基因大豆的生长没有明显影响,而受体材料全部死亡。清水处理下,SHZD32-01与中豆32之间的株高无显著差异,但株高低于喷施草甘膦的处理。喷施草甘膦7 d后,SHZD32-01与受体中豆32的种植小区内杂草全部死亡;28 d后田间浓度草甘膦处理下再次长出杂草的密度和高度与人工除草小区无显著差异。田间种植转基因大豆SHZD32-01在V3期喷施1倍草甘膦即可达到很好的除草效果。

Efficacy of Selected Herbicide Programs in 2,4-D Tolerant Cotton (<i>Gossypium hirsutum</i>L.)

The use of transgenic crops has grown significantly over the past couple of decades. Many agronomic crops produced today are tolerant to glyphosate. Glyphosate-tolerant crops were commercially introduced in 1996, and, about nine years later, glyphosate-resistant Palmer amaranth was confirmed in Georgia. Glyphosate-resistant weeds arose from reliance on postemergence only glyphosate programs to control weeds in crops. New transgenic traits for glufosinate and 2,4-D choline have been developed, and evaluations of stacked traits and concurrent use of multiple herbicides have provided additional tools in the management of glyphosate-resistant weeds. Field experiments were conducted in 2012 and 2013 at the Edisto Research and Education Center near Blackville, SC, USA to determine the efficacy of 2,4-D-based herbicide programs in transgenic cotton tolerant to 2,4-D choline, glyphosate, and glufosinate. The treatments provided good to excellent Palmer amaranth and pitted morningglory control in 2012 and 2013. Seed cotton yields across treatments ranged from 0 to 2057 kg ha-1. This new trait technology package in cotton permits in-season postemergence use of 2,4-D choline, a herbicide mode of action not previously used postemergence in cotton, which can control resistant weeds, including Palmer amaranth if applied at the proper growth stage.

Evaluation of 2,4-D-Choline Based Herbicide Systems in 2,4-D Tolerant Soybean (<i>Glycine max</i>L.)

Weeds are the most limiting factor in soybean production in South Carolina. With early emergence and rapid growth, weeds effectlively compete for water, nutrients, and light resources. The recent evolution of herbicide resistant weeds has made it increasingly difficult for growers to effectively control weeds in soybean. Glyphosate and ALS-resistant Palmer amaranth biotypes have spread rapidly throughout South Carolina, especially in areas where resistance management is lacking. Soybean varieties have been recently developed with tolerance to 2,4-D. Field experiments were conducted at the Clemson University Edisto Research and Education Center located near Blackville, SC in 2012 and 2013 to evaluate selected 2,4-D choline based herbicide programs for weed management in 2,4-D tolerant soybean. Overall, all herbicide treatments were effective in controlling weeds at the POST2 timing. Palmer amaranth control was excellent;however, pitted morningglory was the most difficult. The 2,4-D plus glyphosate pre-mixture provided excellent control for all three weed species with >95% control at POST2 timing. In these treatments, the rate of 2,4-D choline plus glyphosate (1.09 kg ae ha-1 or 1.64 kg ae ha-1) did not have a significant effect on weed control (P = 0.3772). There was a decrease in pitted morningglory control 3 WAP in 2012 vs 2013 in plots treated with S-metolachlor + fomesafen because of a lack of activating soil moisture in 2012. Results from this study showed that all treatments evaluated provided good to excellent control of all 3 weed species. Based on the herbicide programs evaluated in the study, herbicide resistant weeds, such as Palmer amaranth, can be effectively controlled when treated at the correct growth stage.

Genomic Stability of Palmer amaranth Plants Derived by Macro-Vegetative Propagation

qPCR (quantitative polymerase chain reaction) and random amplified polymorphic DNA (RAPD) were utilized to investigate genetic stability of Palmer amaranth cloned plants over 10 generations. DNA from original parent Palmer amaranth plants (grown from seeds) was re-analyzed using qPCR, and confidence levels for determining ΔΔCt (threshold crossing) values were established. ANOVA was used to determine variation (margin of error) of these ΔΔCt values. This margin of error was applied to qPCR analysis of DNA from eight individual parent plants and their descendants (10th generation) so that possible differences in EPSPS (5-enolpyruvylshikimate-3-phosphate synthase) gene copy number could be ascertained. This method (and the associated error) indicated a lack of agreement in ΔΔCt values of DNA from plants of these two generations. qPCR analysis showed that in five out of eight clones, EPSPS gene copy number varied more than the calculated error (P = 0.05). A second technique to monitor genetic stability, RAPD was used to determine possible changes in genomic DNA due to extended cloning of these regenerated plants. RAPD analysis showed that four out of the eight clones differed when the profiles of the two generations were compared. Results show that qPCR and RAPD analysis point to the fact that several Palmer amaranth clones experienced changes in genome structure over 10 generations. Although the glyphosate resistance trait was retained, results suggest that during cloning studies, the genetic stability of macro-vegetatively propagated lines should be monitored.

抗草甘膦杂草及其抗性机制研究进展

介绍了迄今为止全球发现的13种抗草甘膦杂草的发生、发展,并从草甘膦的吸收、输导和分布,5-烯醇丙酮莽草酸-3-磷酸合成酶(EPSPS)的活性以及抗药性遗传等方面对其抗性机制进行了讨论,指出了中国在未来出现抗草甘膦杂草的潜在风险性,并提出了延缓杂草对草甘膦抗性发生的策略。

抗草甘膦杂草及其检测方法发展现状

草甘膦在世界范围的多年大量使用已经引起了抗草甘膦杂草的产生。本文针对全球迄今为止发现的21种抗草甘膦杂草的发生、发展状况进行了论述。探讨了抗草甘膦杂草抗药性检测方法,分别从整株生物测定及生物化学等方面介绍了抗草甘膦杂草检测方法的研究现状,为抗草甘膦杂草检测方法的发展及其抗性监测方法的建立提供参考。

抗草甘膦杂草的抗性机理研究进展

草甘膦因其独特而优异的理化特性,自上市起便受到广泛的关注,现在已经成为全世界应用最广的除草剂之一。但是随着草甘膦抗性杂草的不断出现,草甘膦的应用前景受到严峻的挑战。文章综述了草甘膦生产及应用现状、草甘膦作用机理和草甘膦抗性杂草的发展,重点阐述了草甘膦抗性杂草的抗性机理。最后对如何通过延缓草甘膦抗性杂草的出现,保护草甘膦提出建议。

耐草甘膦杂草控制技术研究

柑桔园行间定向喷雾试验结果表明,在41%农达AS中加入70%苯嘧磺草胺WG和助剂Dash不仅能有效控制乌蔹莓、铁苋菜、假一年蓬、加拿大一枝黄花等多种耐草甘膦阔叶杂草的危害,控制多年生杂草的再生,而且作用速度可与20%克无踪AS相当,对柑桔生长安全。从高效、经济、安全的角度综合考虑,三者混用的适宜剂量为41%农达AS 1 000～1 500 g ai/hm^2＋70%苯嘧磺草胺WG 12.5～25.0 g ai/hm^2＋助剂Dash（喷液量的1%）。

杂草对草甘膦抗性机制及治理对策

杂草对草甘膦的抗药性发生日趋严重,给农业生产带来严重经济损失,已成为杂草抗药性研究的热点问题。本文综述了杂草对草甘膦的抗药性机制研究进展,提出了抗草甘膦杂草的防除措施。

杂草对草甘膦抗性的发展及其治理

草甘膦以其广谱、对环境友好和低毒而成为世界最重要的除草剂,然而,对于同一作用机制除草剂的过度依赖及长期使用会导致杂草群落变迁及产生抗性,在选择压力作用下,杂草对草甘膦产生抗性,特别是随着抗草甘膦作物的扩大种植,杂草对草甘膦的抗性显著增强,为此综述了世界范围内抗草甘膦杂草的现状及预防杂草对草甘膦抗性发展的治理。

抗草甘膦转基因玉米AG16分子特征和抗性鉴定

抗草甘膦转基因玉米(Zea mays)能有效降低杂草防治成本,具有重要的应用前景。浙江大学转基因抗虫植物和生物安全实验室前期通过农杆菌介导法,以玉米Hi-Ⅱ品种为受体导入新型抗草甘膦基因G10evo,获得不同的抗草甘膦玉米转化系。在此基础上,筛选了具有良好草甘膦抗性的转基因玉米转化系AG16。本研究利用PCR、Western杂交、Southern杂交、ELISA等方法对AG16进行分子特征检测,并对AG16的草甘膦抗性水平进行鉴定。结果表明,G10evo在AG16中为单拷贝插入;G10evo蛋白在AG16的根、茎和叶组织中表达;ELISA分析表明,草甘膦喷洒前,嫩茎中G10evo蛋白的表达量达到9.975μg·g-1。温室中草甘膦抗性测定结果显示,AG16能抗4~8倍田间浓度的草甘膦,远高于草甘膦在实际生产中的使用量。因此,AG16草甘膦抗性水平达到生产需求,具有产业应用潜力,为培育具有自主知识产权的抗草甘膦玉米提供了种质资源。

草甘膦施用量对转基因玉米杂草防效、产量以及CP4-EPSPS合酶表达的影响

为了解草甘膦施加量对种植于内蒙古农牧业科学院生物育种科研试验基地的转基因玉米杂草防效、产量以及CP4-EPSPS合酶表达量的影响,本文对转基因玉米DBN9936系列远科105品种进行2250 mL/hm^(2)、3000 mL/hm^(2)和3750 mL/hm^(2)41%草甘膦处理,提取并测定远科105D品种中CP4-EPSPS蛋白的表达量,结合施药过程中的药害、除草效果、产量的测定等数据。研究结果表明:转基因玉米DBN9936系列远科105D品种中抗草甘膦蛋白CP4-EPSPS为组成型表达蛋白,在玉米的不同生育期内都能稳定表达,并不与草甘膦的施加量成正比。在喷洒草甘膦后的第45 d进行杂草统计:施加3750 mL/hm^(2)的41%草甘膦可以将田间94.8%的稗、藜、反枝苋、狗尾草、蒺藜等杂草清除掉,而施加3000 mL/hm^(2)的41%草甘膦除草率为93.1%,施加2250 mL/hm^(2)的草甘膦除草率为87.7%。产量数据表明,有效防控草害能提高玉米产量约16%,而不同草甘膦施药量对玉米的增产并不明显。综上,考虑到内蒙古中西部沙壤土中主要杂草的种类和数量,喷洒2250mL/hm^(2)的草甘膦是既节约成本,也能有效除草,并且也不会明显降低产量的一个合适的施药量。

抗草甘膦杂草检测方法的研究进展

目前,抗草甘膦杂草问题日趋严重。通过检索国内外抗草甘膦杂草的检测方法,总结出常用检测方法和其他检测方法,进行了简单概述,为抗草甘膦杂草检测体系的发展提供依据。