不同除草剂对空心莲子草的控制作用评价

采用盆栽试验,测定了氯氟吡氧乙酸、草甘膦和五氟磺草胺对不同生育期空心莲子草的控制作用,以株防效、鲜重防效和再生抑制率为指标,评价了不同除草剂对空心莲子草的控制效果。结果表明,药后7 d,氯氟吡氧乙酸、草甘膦和五氟磺草胺对不同生育期空心莲子草的株防效,均低于15%;药后15 d,氯氟吡氧乙酸和草甘膦对不同生育期的空心莲子草的株防效、鲜重防效均达100%,但五氟磺草胺对不同生育期的空心莲子草的株防效较差。药后30 d,氯氟吡氧乙酸和五氟磺草胺对不同生育期空心莲子草的再生抑制作用较强,抑制效果达74%以上;草甘膦对生长后期的再生抑制作用达81.3%。空心莲子草苗期对不同除草剂的反应最为敏感。氯氟吡氧乙酸可以作为水生环境和旱生环境下防除空心莲子草的重点药剂,草甘膦可用于旱地空心莲子草的防除,五氟磺草胺可作为水生环境条件下防除空心莲子草的主要药剂之一。     

三氯吡氧乙酸、氯氟吡氧乙酸、2甲4氯和草甘膦对葎草的防除活性比较

本文通过温室整株生物测定法比较研究了三氯吡氧乙酸、氯氟吡氧乙酸、2甲4氯钠和草甘膦异丙胺盐4种常用于水稻、小麦种植区防控大龄阔叶杂草的茎叶处理除草剂对6～8叶期葎草Humulus scandens的防除活性。结果表明,在210 g/hm~2剂量下,三氯吡氧乙酸和氯氟吡氧乙酸可完全杀灭供试葎草植株,在420 g/hm~2剂量下,2甲4氯钠对葎草的鲜重抑制率达到95.25%,而草甘膦异丙胺盐840 g/hm~2剂量处理对葎草的鲜重抑制率仍不足80%。进一步通过Logistic曲线模型分析除草剂对葎草鲜重抑制率达到50%和90%的剂量(GR_(50)和GR_(90)剂量)发现,三氯吡氧乙酸、氯氟吡氧乙酸、2甲4氯钠和草甘膦异丙胺盐相应的GR_(50)分别为58.74、76.96、182.52和272.82 g/hm~2; GR_(90)分别为143.97、202.83、678.27和2 980.11 g/hm~2。结论:对于水稻、小麦种植区葎草危害,优先推荐使用三氯吡氧乙酸防除,其次是氯氟吡氧乙酸;使用2甲4氯防控效果不够理想,使用草甘膦无法有效控制。     

江苏省不同地区猪殃殃种群对常用除草剂的敏感性差异

采用整株生测法测定采自江苏省不同地区的20个猪殃殃种群对麦田常用除草剂苯磺隆、苄嘧磺隆、二甲四氯钠、氯氟吡氧乙酸、唑草酮的敏感性差异。结果表明,苯磺隆处理后,20个种群中有12个种群的ED50值超过推荐剂量,对苯磺隆产生明显的抗性;12个抗苯磺隆种群中有10个种群对苄嘧磺隆产生交互抗性,4个种群对二甲四氯钠产生多抗性,但对氯氟吡氧乙酸、唑草酮敏感;抗乙酰乳酸合酶(ALS)抑制剂类除草剂的猪殃殃种群比例呈现苏南到苏北逐渐增加的趋势,苯磺隆和苄嘧磺隆间存在交互抗性,部分抗ALS种群对二甲四氯钠具有多抗性,但抗性种群均对氯氟吡氧乙酸、唑草酮敏感。     

11种稻田除草剂对丁香蓼的室内生物活性

采用室内盆栽试验方法开展了11种稻田常用除草剂对丁香蓼生物活性研究, 结果表明:在丁香蓼芽前使用10％吡嘧磺隆WP、40%苄嘧·丙草胺WP, 0~2叶期使用19%氟酮磺草胺SC、120 g/L噁草酮EC, 2~4叶期使用200 g/L氯氟吡氧乙酸EC、3%氯氟吡啶酯EC、25 g/L五氟磺草胺OD、〖JP+2〗100 g/L双草醚SC和4~6叶期使用460 g/L 2甲·灭草松AS, 对丁香蓼的ED90分别为4.18、10.30,1.61、241.60,7.31、9.74、11.83、28.96和117.73 g/hm2, ED90均低于供试药剂的田间常用推荐剂量, 证明丁香蓼对上述药剂敏感, 可作为生产上防除丁香蓼的候选药剂。     

四川省烟田空心莲子草危害调查及化学防除

采用倒置九点取样法对四川省烟田空心莲子草的发生及危害进行调查,并通过小区试验考察氯氟吡氧乙酸、百草枯、草铵膦3种除草剂对空心莲子草的防效。结果显示,空心莲子草在四川烟田的发生频率、相对多度和草害综合指数分别达到43.82%、9.96%和4.83%。20%氯氟吡氧乙酸乳油对空心莲子草的防除效果最佳,900、1050 m L/hm2处理26 d对空心莲子草的株鲜质量防效分别达到94.56%、95.97%,且持效性较好。安全性试验结果表明,烟草对氯氟吡氧乙酸敏感,施药时应注意避免将药液喷施到烟草茎叶上。     

30种除草剂对豚草和薇甘菊的防效初步评价

为了筛选出防除豚草和薇甘菊的新型高效除草剂品种,采用茎叶喷雾法,测定30种除草剂对盆栽豚草和薇甘菊的防除效果。辛酰溴苯腈375 g /hm2、麦草畏216 g /hm2、百草枯600 g /hm2、草铵膦540 g /hm2、草甘膦异丙胺盐922.5 g /hm2、乙羧氟草醚90 g /hm2、三氟羧草醚540 g /hm2、氟磺胺草醚427 g /hm2、莠去津1 140 g /hm2、莠灭净3 000 g /hm2和灭草松1 440 g /hm2对豚草防除效果好,药后30 d鲜重防效达100%;对薇甘菊防效较好的有辛酰溴苯腈375 g /hm2、麦草畏216 g /hm2、2,4-滴钠盐125 g /hm2、氯氟吡氧乙酸180 g /hm2、氯氟吡氧乙酸异辛酯150 g/hm2、草铵膦540 g /hm 2、草甘膦异丙胺盐922.5 g /hm2、灭草松1 440 g /hm2和百草枯600 g/hm2,药后30天鲜重防效达98%以上。本试验结果将为豚草和薇甘菊的化学防控提供有益参考。     

6种除草剂对豚草的田间防治效果

化学防治是一种对恶性入侵杂草豚草有效的防治措施,可在IPM中作为应急手段.为筛选出对豚草具高效的除草剂品种,采用茎叶喷雾法,在田间测定了草甘膦、百草枯、氟磺胺草醚、乳氟禾草灵、氯氟吡氧乙酸、双氟磺草胺·唑嘧磺草胺6种除草刘对豚草的防治效果.结果表明,无论是苗期(株高30 cm)还是成株期(株高60 cm),除双氟磺草胺·唑嘧磺草胺,参试除草剂均对豚草表现出良好的防治效果.可见,草甘膦、百草枯、氟磺胺草醚、乳氟禾草灵、氯氟吡氧乙酸均可应用于防治野外发生的豚草.     

枣阳市鸭跖草发生特点及防除

鸭跖草危害夏播作物越来越严重,通过对鸭跖草的生长特点观察,发生原因分析以及防除药剂筛选,得出麦后棉移栽后,在鸭跖草三叶前和分枝期定向喷雾防除,总体防效草甘磷＋乙羧氟草醚〉草甘磷〉百草枯;玉米地,玉米六叶期防除,总体防效氯氟吡氧乙酸十二甲四氯〉莠去津＋烟嘧油悬浮剂＋氯氟吡氧乙酸〉莠去津＋烟嘧磺隆。药剂防除鸭跖草,要掌握在鸭跖草二叶期到三叶期,苗越小,防除越早,防治效果越高。     

有效防除麦田抗性杂草荠菜的新型除草剂——双唑草酮

双唑草酮为中国创制的新型对羟基苯基丙酮酸双氧化酶(HPPD)抑制剂类除草剂,已于2018年取得中国农药登记。为了测定其对麦田抗性杂草荠菜的除草效果,共采集了36个荠菜种群,其中1个敏感种群采自未施用过除草剂的路边,其他35个疑似抗性种群均采自于中国苯磺隆使用历史超过20年的冬小麦田。在温室中采用整株盆栽法测定了荠菜种群对双唑草酮、苯磺隆、双氟磺草胺、甲基二磺隆、唑草酮和2甲4氯的抗性水平。结果表明,有28个种群对苯磺隆产生了抗性,其中种群K16009、K17005、15053和17003表现出高水平抗性。这4个种群对其他除草剂的交互抗性检测试验表明:种群K16009、K17005和15053对双氟磺草胺和甲基二磺隆表现出高水平交互抗性,其抗性指数范围为25-321,其GR₅₀值远高于供试药剂登记的田间推荐剂量;而上述4个抗性种群对双唑草酮、唑草酮和2甲4氯均较为敏感,其GR₅₀值均低于供试药剂登记的田间推荐剂量。唑草酮和2甲4氯也可用于小麦田抗性荠菜种群的防治,但该类药剂对施药时间要求较为严格。本研究结果表明,双唑草酮可有效防除对乙酰羟基酸合成酶（AHAS）类除草剂已经产生抗性的荠菜。     

抗草铵膦转基因水稻‘Y0003’直播田除草剂施用技术研究

为给抗草铵膦转基因水稻‘Y0003’商业化生产后除草剂的安全高效施用提供科学依据, 探索了该转基因直播稻田草铵膦的最佳施用时期和施用剂量。研究了在直播稻田3~4叶期、5~6叶期以及分蘖期施用0.225、0.45和0.9 g/hm 2草铵膦(有效成分, 下同)后, 草铵膦对杂草的控制效果和对转基因水稻生长的影响。在测试的3个施药时期, 施用0.225 g/hm 2草铵膦对杂草防除效果都很差, 水稻减产严重; 在水稻3~4叶期和分蘖期施用0.45和0.9 g/hm 2草铵膦对杂草的防除效果也较差, 水稻生长受到严重影响, 与无草对照相比水稻产量显著下降。但在水稻5~6叶期施用0.45 和0.9 g/hm 2草铵膦对主要杂草的防效均在90%以上, 且对水稻安全。因此建议抗草铵膦转基因水稻‘Y0003’直播田在水稻5~6叶期施用0.45~0.9 g/hm 2草铵膦来控制田间杂草。     

Specific microbial responses to herbicides*

Examples from the literature and from the authors’own laboratory demonstrate that herbicides can exert adverse effects on the soil micro-flora, depending on concentration, though often at higher rates than the herbicidal dose. Examples refer to changes in microbial growth (asulam, linuron, paraquat) and equilibrium (metoxuron), respiration and nitrification in samples from field experiments (linuron, simazine) and laboratory experiments (bentazone, glyphosate, barban, etc.), enzyme activities (urease, phosphatase; barban, chlorpropham, linuron) and the decay of sprayed vegetation (glyphosate, paraquat).     

Paraquat-resistant biotypes of Hordeum glaucum from zero-tillage wheat

There has been a significant increase in the area seeded to minimum- and zero-tilled crops worldwide over the past two decades. These cropping systems rely primarily on the non-selective herbicides glyphosate or paraquat/diquat to control weeds before seeding the crop. Both glyphosate and paraquat/diquat are regarded as low-risk herbicides in the ability of target weeds to develop resistance to them. Following 10–15 years of once annual applications of paraquat and diquat for weed control in zero-tilled cereals, failure of these herbicides to control Hordeum glaucum Steud. in two separate fields occurred. Dose–response experiments demonstrated high-level resistance to paraquat and diquat in both populations; however, the resistant biotypes are susceptible to other herbicides. This is the first report, worldwide, of paraquat resistance following the use of this herbicide in zero-tillage cropping systems and is therefore a harbinger of future problems in minimum-tillage systems when there is exclusive reliance on a contact herbicide for weed control.     

The seasonal response of Lantana camara to selected herbicides

At 7- to 8-week intervals between September 1990 and February 1993, blocks of Lantana camara L. cv. `Helidon White' were treated with four herbicides (fluroxypyr, metsulfuron-methyl, glyphosate and dichlorprop) as an overall high-volume spray at the recommended label rates. Mortality for each treatment was recorded and correlated with climatic data (maximum, minimum air and soil temperature, rainfall, day length and humidity) recorded for the site. Fluroxypyr killed more than 90% of the L. camara if at least 35 mm of rain was received in the preceding 6 weeks and provided that the average minimum daily temperature for the week before the application was above 15 °C. Similarly, glyphosate caused more than 80% mortality when the rainfall was greater than 60 mm in the preceding 6 weeks, with a similar temperature requirement to fluroxypyr. In contrast, dichlorprop and metsulfuron-methyl caused maximum kills of 35–80% and 83% respectively. This occurred in the summer or early autumn (at times when fluroxypyr and glyphosate also gave maximum kills), but times of maximum kill for dichlorprop and metsulfuron-methyl did not correlate with any specific climatic characteristics. Current field practice is to apply all herbicides in autumn (March–May) when L. camara is growing actively. The consequence of this is that, if some plants are not killed, they can go undetected until the next growing season. However, this study shows that fluroxypyr and glyphosate can be sprayed earlier in the year, thus allowing for follow-up sprays later in the same growing season to kill any regrowth.     

Multiple resistance across glufosinate,glyphosate, paraquat and ACCase‐inhibiting herbicides in an Eleusine indica population

An Eleusine indica population was previously reported as the first global case of field‐evolved glufosinate resistance. This study re‐examines glufosinate resistance and investigates multiple resistance to other herbicides in the population. Dose–response experiments with glufosinate showed that the resistant population is 5‐fold and 14‐fold resistant relative to the susceptible population, based on GR₅₀ and LD₅₀ R/S ratio respectively. The selected glufosinate‐resistant subpopulation also displayed a high‐level resistance to glyphosate, with the respective GR₅₀ and LD₅₀ R/S ratios being 12‐ and 144‐fold. In addition, the subpopulation also displayed a level of resistance to paraquat and ACCase‐inhibiting herbicides fluazifop‐P‐butyl, haloxyfop‐P‐methyl and butroxydim. ACCase gene sequencing revealed that the Trp‐2027‐Cys mutation is likely responsible for resistance to the ACCase inhibitors examined. Here, we confirm glufosinate resistance and importantly, we find very high‐level glyphosate resistance, as well as resistance to paraquat and ACCase‐inhibiting herbicides. This is the first confirmed report of a weed species that evolved multiple resistance across all the three non‐selective global herbicides, glufosinate, glyphosate and paraquat.     

Control by glyphosate and its alternatives of glyphosate‐susceptible and glyphosate‐resistant Echinochloa colona in the fallow phase of crop rotations in subtropical Australia

Echinochloa colona is the most common grass weed of summer fallows in the grain‐cropping systems of the subtropical region of Australia. Glyphosate is the most commonly used herbicide for summer grass control in fallows in this region. The world's first population of glyphosate‐resistant E. colona was confirmed in Australia in 2007 and, since then, >70 populations have been confirmed to be resistant in the subtropical region. The efficacy of alternative herbicides on glyphosate‐susceptible populations was evaluated in three field experiments and on both glyphosate‐susceptible and glyphosate‐resistant populations in two pot experiments. The treatments were knockdown and pre‐emergence herbicides that were applied as a single application (alone or in a mixture) or as part of a sequential application to weeds at different growth stages. Glyphosate at 720 g ai ha^?1 provided good control of small glyphosate‐susceptible plants (pre‐ to early tillering), but was not always effective on larger susceptible plants. Paraquat was effective and the most reliable when applied at 500 g ai ha^?1 on small plants, irrespective of the glyphosate resistance status. The sequential application of glyphosate followed by paraquat provided 96–100% control across all experiments, irrespective of the growth stage, and the addition of metolachlor and metolachlor + atrazine to glyphosate or paraquat significantly reduced subsequent emergence. Herbicide treatments have been identified that provide excellent control of small E. colona plants, irrespective of their glyphosate resistance status. These tactics of knockdown herbicides, sequential applications and pre‐emergence herbicides should be incorporated into an integrated weed management strategy in order to greatly improve E. colona control, reduce seed production by the sprayed survivors and to minimize the risk of the further development of glyphosate resistance.     

Diclofop-methyl antagonism by broadleaf weed herbicides: the importance of leaf expansion rate

Avena saliva cv. Amuri and A. fatua were sprayed with diclofop methyl (1.0 kg a.i. ha^?1) alone and in combination with 2,4-D (1.1 kg a.i. ha^?1), bentazone (1.0 kg a.i. ha^?1), chlorsulfuron (15 g a.i. ha^?1) or dicamba (0.3 kg a.i. ha^?1). Effects of the herbicides on leaf extension rate during the first 8 to 10 days after spraying and subsequent growth (dry weight) after 57–75 days were determined by comparison with unsprayed plants. Diclofop-methyl applied alone did not cause a decrease in leaf extension rate of A. saliva or A. fatua until at least 4 days after spraying. All broadleaf weed herbicides in combination with diclofop-methyl caused a decrease in leaf extension rate of both species within 2 days of spraying. Ten days after spraying, leaf extension rates for plants sprayed with a broadleaf weed herbicide plus diclofopmethyl (all combinations) were lower than for unsprayed plants but greater than for plants sprayed with diclofop-methyl alone. With the exception of A. fatua sprayed with bentazone, long-term growth of plants sprayed with a broadleaf weed herbicide plus diclofop-methyl (all combinations) was lower than for unsprayed plants but greater than for plants sprayed with diclofop-methyl alone. Bentazone applied with diclofop-methyl caused a substantial decrease in leaf extension rate of A. fatua within 24 h of spraying but at harvest, dry weight of plants from this treatment was similar to or less than that for plants sprayed with diclofop-methyl alone. Application of diclofop-methyl with bentazone at a rate of 0.3 kg a.i. ha^?1 also caused a reduction in leaf extension rate of A. fatua within one day of spraying. At this rate of bentazone, dry weight of plants at harvest was intermediate to that of unsprayed plants and those sprayed with diclofop-methyl alone. It is proposed that decreased leaf expansion rate during the first few days afte spraying is the cause of broadleaf weed herbicide antagonism of diclofop-methyl.     

广东省稻菜轮作区中牛筋草对十种除草剂的抗性水平及靶基因序列分析

为明确广东省稻菜轮作区中牛筋草对10种常用除草剂的抗性水平及抗性分子机制,采用整株生物测定法测定广东省稻菜轮作区内8个牛筋草种群P1～P8对草甘膦、草铵膦和乙酰辅酶A羧化酶(acetyl-CoA carboxylase,ACCase)抑制剂类等10种除草剂的抗性水平,并进一步分析P1和P8种群相关靶标酶基因5-烯醇丙酮酰莽草酸-3-磷酸合酶(5-enolpyruvyl-shikimate-3-phosphate synthase,EPSPS)、谷氨酰胺合成酶(glutamine synthetase,GS)和ACCase的部分功能区序列特征。结果显示,牛筋草P1～P8种群对草甘膦抗性指数为敏感种群的5.9倍～17.7倍,其中P8种群对草甘膦的抗性水平最高;8个种群对草铵膦也产生了不同程度的抗性,抗性指数为敏感种群的2.3倍～14.2倍,其中P1种群抗性最高。牛筋草P1和P8种群均对ACCase抑制剂类除草剂精喹禾灵、氰氟草酯和噁唑酰草胺产生了交互抗性;P1种群ACCase基因在第2 041位氨基酸处发生突变,该突变在牛筋草种群中首次发现;而P8种群ACCase基因则在第2 027位氨基...