甲草胺·乙草胺·莠去津悬浮剂中混有2甲4氯造成棉花药害的技术鉴定

除草剂使用不当所造成的危害已日益成为我国农业可持续发展的一大障碍，而药害的技术鉴定及治理又非常复杂。文章根据棉花受害症状、反应速度、周边杂草受害症状及农药企业的基本生产情况等，初步确定可能造成药害的除草剂种类。利用气质联用仪将供试药害的样品与一些标样在同一条件下的总离子流色谱图和质谱图进行比较，确认甲草胺·乙草胺·莠去津悬浮剂中含有造成棉花药害的2甲4氯，并测定2甲4氯的含量为6．0％。     

常见除草剂药害症状及预防

1常见除草剂药害症状1·1草甘膦农作物受草甘膦药害后,心叶及上部嫩叶先发黄,7~10 d后全株逐渐枯死。农作物根边杂草同样有发黄枯死现象。若在喷洒草甘膦后喷雾器械未彻底清洗,又在棉花子叶平展期用于喷洒杀菌剂,棉花子叶无变化,新出的真叶发黄,生长停滞。1·2克无踪上午农作物正常,喷药后下午突然青枯,包括根边杂草。1·3 2甲4氯在大风天气施药,飘移药害距离可达80~100m,棉花、番茄等阔叶作物受害后叶片产生鸡爪形症状。在小麦4叶1心期前使用,将产生葱管叶。1·4乙草胺用药浓度过高,棉花、西瓜、花生的叶片畸形,两张叶片粘合。蚕豆在盛花期…     

2.5%吡虫啉可湿性粉剂造成棉花药害的技术鉴定

本文根据棉花受害症状、反应速度、况等,初步确定可能造成药害的20种除草剂。周边杂草受害症状及农药企业的基本生产情利用液相色谱与二极管阵列检测技术．将供试药害样品与20种除草剂标样在同一条件下的保留时间和紫外光谱图进行比较．确认2．5％吡虫啉样品中含有造成棉花药害的苯磺隆,并测定苯磺隆的含量为4．7％。     

苯磺隆、2甲4氯防除谷田杂草的药害与增产效果

苯磺隆、2甲4氯两种除草剂防除谷田杂草时,施药前期对谷子表现药害症状,后期消失,对产量的影响较小。     

农药药害发生后的补救措施

l 施肥补救 对产生叶面药斑，叶缘枯焦或植株黄化等症状的药害时，增施肥料可减轻药害程度。 l 排灌补救 对一些除草剂引起的药害，适当排灌可以减轻药害的程度。 l 激素补救 对于抑制或干扰植物的除草剂，如2甲4氯、甲草胺、杀草丹、禾大壮等在发生药害后，喷洒赤霉素可缓解药害程度。 农药药害发生后的补救措施     

皖南稻田除草剂药害发生现状及其预防对策

皖南稻区水稻除草剂药害呈现发生频率高、大型事故增多、影响层面广泛的新特点。造成药害的主要除草剂包括磺酰脲类的胺苯磺隆、甲磺隆、氯磺隆、甲嘧磺隆,灭生性除草剂草甘膦、百草枯,酰胺类的乙草胺、丙草胺、异丙甲草胺,以及2甲4氯、二氯喹啉酸等。药害原因可分为使用者原因、生产者原因、经营推广者原因、环境因素影响等多种。介绍了缓解药害的经验措施。提出从源头上加强除草剂登记与质量管理．在销售和使用环节加强对有关人员的专业知识培训．严格试验示范推广程序,谨慎使用除草剂等预防对策。     

小麦田常用除草剂药害及其规避措施

多种小麦田常用除草剂在使用不当时容易对当茬小麦或后茬作物产生药害。从近年来江苏等地的情况看,异丙隆等除草剂药害发生面积较大;氯磺隆、甲磺隆等除草剂对后茬直播稻、大豆等作物的残留药害发生面积也较大,而且危害严重;唑草酮、甲基二磺隆、精嗯唑禾草灵、乙羧氟草醚、乙草胺、2甲4氯等除草剂药害也时有发生。现对有关除草剂药害形成的原因作简要分析,并提出规避药害的措施,以供参考。     

浅谈草甘膦对棉花的药害及预防

棉花是新余市渝水区最主要的经济作物.每年种植面积6 000 hm2左右.棉田除草是棉花生产上一项重要的措施,使大量的农村劳力从繁重的劳动中解放出来,提高了生产率.但棉田除草剂的连续多年大量使用,其药害问题已日益显现.表现最为突出的是草甘膦,AS的药害.近年各植棉乡镇草甘膦药害现象屡见不鲜,反映十分强烈.据统计,本区20世纪90年代后期局部零星发生,后逐年加重,2006～2007年全区年发生药害面积267～400 hm2,受害田块被害株率10%～30%,高的达90%以上,产量损失10%～20%,高的50%以上,每年因药害造成翻耕改种或严重减产棉田达13 hm2以上.为确保棉花生产的更好发展,笔者对草甘膦对棉花的药害进行了多年的调查研究,并提出相应的预防对策.     

几种除草剂对恶性杂草野艾蒿的防除效果及对胡麻生长发育的影响

采用田间试验的方法,测定了几种除草剂单剂和混用配方对胡麻田恶性杂草野艾蒿的防除效果及对胡麻生长发育的影响。结果显示,75%二氯吡啶酸SG+56%2甲4氯钠盐SP、75%二氯吡啶酸SG+90%莠去津WG混配、75%二氯吡啶酸SG单剂对野艾蒿的株防效、地上部鲜重防效、地下部鲜重防效分别达到93.24%～97.46%、94.69%～96.77%和90.13%～96.40%,对靶标杂草野艾蒿防除效果明显且对胡麻无药害,胡麻产量较空白对照分别增加36.59%、4.14%和20.86%。48%灭草松AS虽对野艾蒿的综合防效较低,但其对胡麻无药害且胡麻蒴果数、千粒重较大,胡麻产量较空白对照增长61.27%。90%2甲·草甘膦SP、82%草甘膦异丙胺盐AS、20%氯氟吡氧乙酸EC、70.5%2甲·唑草酮WG、20%敌草快AS 5种除草剂对胡麻安全性低,不宜应用于胡麻田野艾蒿的防治。结合各除草剂处理后胡麻的药害、经济性状、生物产量、籽粒产量以及对野艾蒿的防除效果进行综合分析,胡麻田野艾蒿防除除草剂选择适宜度依次为:75%二氯吡啶酸SG+56%2甲4氯钠盐SP混配75%二氯吡啶酸SG48%灭草松AS75%二氯吡啶酸SG+90%莠去津WG混配。本文为胡麻田恶性杂草野艾蒿的化学防除提供了理论依据。     

河北成安、广平等县发生大面积棉花药害

据国家农药质量监督检验测试中心反映,河北省邯郸地区成安县,今年6～7月份因施用邢台市农药厂6月份加工分装的2.5％敌杀死乳油造成1000多亩棉花的药害。广平县也因相同原因受害棉花地达500～600亩。棉株受害症状为:幼叶扭曲呈鸡爪状,生长停止,为典型的2,4-滴丁酯药害症状。     

Increased metabolism of a pyrrolidine urea herbicide in corn by a herbicide antidote

Corn, cotton, and sorghum plants were injured by high rates of 5328 (cis-2,5-dimeihyl-1-pyrrolidinecarboxanilide) when it was applied to the soil surface al planting time. The injury was severe al 35·84 kg/ha (eight times recommended dosage) and in corn resulted in complete inhibition of adventitious root development and reduced shoot and primary and secondary root growth. Treatment of the seeds with 0·5% Protect (1,8-naphthalic anhydride) prior to planting dramatically decreased the injurious effect of 5328 on corn, sorghum, and cotton. Using ¹⁴C-5328 in corn, it was shown that Protect did not alter herbicide uptake. However, the rate of conversion of the herbicide molecule in corn tissue lo water soluble, nonherbicidal metabolites was markedly enhanced in plants grown from Protect-treated seeds.     

Control of purple nutsedge (Cyperus rotundus) in cotton with benfuresate

The herbicide benfuresate applied preplanting to cotton (Gossypium hirsutum L.) fields infested with purple nutsedge (Cyperus rotundus L.) inhibited nutsedge growth for several weeks and was found selective for cotton. The best nutsedge control was achieved when the herbicide was mechanically incorporated following a preplant broadcast or band application which was activated by a sprinkler irrigation. The rate of benfuresate needed for effective and selective nutsedge control in cotton ranged from 0.80 to 1.60 kg/ha, the higher rates necessary in soils with higher clay and organic matter contents.     

Tillage and herbicide treatments with inter‐row cultivation influence weed densities and yield of three industrial crops

Field experiments were conducted in northern Greece in 2003 and 2004 to evaluate effects of tillage regimes (moldboard plowing, chisel plowing, and rotary tilling), cropping sequences (continuous cotton, cotton‐sugar beet rotation, and continuous tobacco) and herbicide treatments with inter‐row hand hoeing on weed population densities. Total weed densities were not affected by tillage treatment except that of barnyardgrass (Echinochloa crus‐galli), which increased only in moldboard plowing treated plots during 2003. Redroot pigweed (Amaranthus retroflexus) and black nightshade (Solanum nigrum) densities were reduced in continuous cotton, while purple nutsedge (Cyperus rotundus), E. crus‐galli, S. nigrum, and johnsongrass (Sorghum halepense) densities were reduced in tobacco. A. retroflexus and S. nigrum were effectively controlled by all herbicide treatments with inter‐row hand hoeing, whereas E. crus‐galli was effectively reduced by herbicides applied to cotton and tobacco. S. halepense density reduction was a result of herbicide applied to tobacco with inter‐row hand hoeing. Yield of all crops was higher under moldboard plowing and herbicide treatments. Pre‐sowing and pre‐emergence herbicide treatments in cotton and pre‐transplant in tobacco integrated with inter‐row cultivation resulted in efficient control of annual weed species and good crop yields. These observations are of practical relevance to crop selection by farmers in order to maintain weed populations at economically acceptable densities through the integration of various planting dates, sustainable herbicide use and inter‐row cultivation; tools of great importance in integrated weed management systems.     

Chemical cotton stalk destruction for maintenance of host-free periods for the control of overwintering boll weevil in tropical and subtropical climates

In the Lower Rio Grande Valley (LRGV) of Texas, cotton regrows and produces fruit from undestroyed stalks throughout the winter, and in spring weevils from such locations become a serious threat. The success of the boll weevil eradication program, which was reintroduced in the LRGV in 2005, will be dependent on thorough stalk destruction following harvest. However, adverse weather conditions and conservation tillage often impede immediate and complete stalk destruction using typical tool implements, and alternative stalk control methods are needed. This study provides an examination of the efficacy for cotton stalk destruction of different herbicides (thifensulfuron-methyl + tribenuron-methyl, dicamba-diolamine, 2,4-D-dimethylammonium, flumioxazin, 2,4-DB-dimethylammonium and carfentrazone-ethyl) and their rates, spray volumes and application timings on shredded or standing cotton stalks after stripper or picker harvest. None of the tested herbicides, except 2,4-D-dimethylammonium, stopped post-harvest cotton regrowth and fruiting. 2,4-D-dimethylammonium sprayed once (0 or 7 days) after cotton was harvested at 1 lb AE acre(-1) (1.12 kg ha(-1)), in a spray volume of 10 gal water acre(-1) (93.5 L ha(-1)) with 5 mL L(-1) surfactant, was highly effective in stalk destruction (72-90%). The best results were achieved when the herbicide was applied immediately after the cotton was shredded, followed by standing stripper-harvested and standing picker-harvested cotton. 2,4-D-dimethylammonium applied twice, 0 and 14 (or 21) days after cotton harvest, was 100% effective in killing stalks, regardless of whether they were shredded or standing, or whether harvest was by stripper or picker. These findings showed that 2,4-D-dimethylammonium cotton stalk destruction eliminated food and reproductive opportunities for managing overwintering boll weevils [Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae)].     

Influence of propaquizafop application rate and time on Sorghum halepense (L.) Pers. control and cotton (Gossypium hirsutum) yield

Field experiments were carried out from 1990 through 1992 to study the effect of propaquizafop application rate and application timing of fluazifop, haloxyfop, propaquizafop, quizalofop, and hoeing on Sorghum halepense (L.) Pers. control and seed cotton yield. Control of S. halepense with propaquizafop applied to plants 20–35 cm tall was not affected by rate of application and was similar to that obtained with fluazifop applied at the recommended rate. Cotton yield following all herbicide treatments was greater than that of the weedy control, but lower than that of the weedfree control. S. halepense control with fluazifop, haloxyfop, propaquizafop, and quizalofop applied to plants 20–35 or 35–80 cm tall was greater than that obtained with their application to plants 5–15 or 10–25 cm tall. Ho-eing, applied once at any S. halepense growth stage, provided less control than any herbicide treatment on the same date. Cotton yield was increased by all herbicide treatments and hoeing compared to that of the weedy control, but the highest yield was obtained after herbicide appli-cation to S. halepense plants 10–25 cm tall. However, none of the herbicide treatments or hoeing increased cotton yield to the level of the weedfree control.     

A simulation of herbicide use based on weed spatial distribution

Intensive field surveys were conducted to deter mine the spatial distribution of composite broad leaf and grass weed seedlings in seven maize and five soybean fields in eastern Nebraska in 1992. Farmer fields where herbicides were applied in a 38-cm band over 76-cm spaced rows were chosen for this study. Weed populations were measured in the interrow and in the band-treated intrarow. Spatial maps constructed for grass or broadleaf weeds revealed that individual species as well as species assemblages are highly aggregated. On average, 30% of the sample area in the 12 fields surveyed was free of broadleaf weeds and 70% free of grass weeds in the interrow area (no her bicide). Where a pre-emergence herbicide was applied (intrarow), 71% of the sample area was free of broadleaf weeds and 94% free of grass weeds. Increasing the threshold to some value other than zero resulted in a larger field area not requiring a herbicide application. The results of these distribution studies indicate that herbicide use could be substantially reduced if weed dis tribution maps or real-time plant sensing were available to provide information for intermittent herbicide application systems or refinement of economic thresholds.     

转基因棉花的研发现状与发展策略

国内外转基因棉花的研发主要集中于抗虫、耐除草剂、抗病、纤维改良、抗旱和耐盐碱等性状,但只有抗虫、耐除草剂棉花注册应用。自1996年商业化种植以来,年种植面积逐年上升,到2010年全世界转基因棉花的种植面积已达2 100万hm2。转基因棉花的大规模种植,对有效控制棉花害虫与杂草的发生为害发挥了重要作用,显著降低了生产成本,提高了棉花产量。本文综述了国内外转基因棉花的研发动态及其商业化进程,并结合我国棉花产业发展需求,提出了我国转基因棉花的发展对策。     

Benchmark study on glyphosate-resistant cropping systems in the United States. Part 4: Weed management practices and effects on weed populations and soil seedbanks

BACKGROUND: Weed management in glyphosate‐resistant (GR) maize, cotton and soybean in the United States relies almost exclusively on glyphosate, which raises criticism for facilitating shifts in weed populations. In 2006, the benchmark study, a field‐scale investigation, was initiated in three different GR cropping systems to characterize academic recommendations for weed management and to determine the level to which these recommendations would reduce weed population shifts. RESULTS: A majority of growers used glyphosate as the only herbicide for weed management, as opposed to 98% of the academic recommendations implementing at least two herbicide active ingredients and modes of action. The additional herbicides were applied with glyphosate and as soil residual treatments. The greater herbicide diversity with academic recommendations reduced weed population densities before and after post‐emergence herbicide applications in 2006 and 2007, particularly in continuous GR crops. CONCLUSION: Diversifying herbicides reduces weed population densities and lowers the risk of weed population shifts and the associated potential for the evolution of glyphosate‐resistant weeds in continuous GR crops. Altered weed management practices (e.g. herbicides or tillage) enabled by rotating crops, whether GR or non‐GR, improves weed management and thus minimizes the effectiveness of only using chemical tactics to mitigate weed population shifts. Copyright © 2011 Society of Chemical Industry     

Matching herbicide application rates with the environmental conditions and growth stages of nodding thistle (Carduus nutans) and hairy buttercup (Ranunculus sardous) in pastures

Glasshouse experiments were conducted to evaluate whether herbicide application rates could be reliably reduced without compromising the efficacy of the herbicide. The seedling, and vegetative and preflowering plants of nodding thistle ( Carduus nutans ) and hairy buttercup ( Ranunculus sardous ) were treated with different rates of glyphosate or a mixture of picloram and triclopyr. Half of the plants were well-watered at all times while the other half was moisture-stressed for 1 week before the herbicide treatments were applied. Hairy buttercup was more susceptible to glyphosate than nodding thistle, while both were equally susceptible to the picloram/triclopyr mixture. Moisture stress significantly reduced the efficacy of both herbicide treatments, regardless of the plant development stage or the herbicide rate applied.