微生物除草剂与生物安全

随着人类环境意识的提高和农业可持续发展的需要,高效、环保微生物除草剂的研究越来越显示其重要的社会意义和经济价值。本文概述了微生物除草剂的种类、剂型及特点,介绍了利用微生物及其天然产物防治杂草的潜在优势和目前国内外的研究进展,尤其是对微生物除草剂的生物安全性进行了评价。     

Effects of some phenylurea herbicides on photosynthesis of two wheat varieties

Photosynthesis in the shoots of winter wheat (Triticum aestivum L.) was inhibited by certain phenylurea herbicides applied via the nutrient solution. Recovery from this inhibition after short treatments was used as a measure of the rate of inactivation of these herbicides in the leaf tissue of a variety tolerant to metoxuron (Caribo) and of a less tolerant variety (Manella). The introduction of chlorine atoms into fenuron greatly reduced the rate of inactivation in both varieties, whereas that of a methyl or butoxy group had little or no effect. Metoxuron was inactivated more readily than chlortoluron and both compounds were inactivated more rapidly in Caribo than in Manella.     

Catalytic effect of dissolved humic acids on the chemical degradation of phenylurea herbicides

BACKGROUND: Although biodegradation seems to be the main cause of herbicide degradation, abiotic degradation can also be important for chemicals such as phenylureas, which are subject to catalysed soil reactions. The aim of this work is to investigate the effect of dissolved humic acids (HAs), normally present in natural waters, on the hydrolysis of phenylurea herbicides, and it presents a kinetic model that takes into account the role of adsorption. RESULTS: The linearity of the adsorption isotherms indicates that phenylurea-humic acid interaction can be considered in terms of a repartition-like equilibrium of phenylurea between water and HAs. Kinetic experiments show that the degradation rates of phenylureas increase with HA concentration. CONCLUSION: The kinetic equation adopted adequately describes the experimental data trend, allowing the evaluation of the catalytic effect of HAs on the chemical degradation of phenylureas. Carboxyl groups of HAs seem to play a leading role in the catalysis. The kinetic equation derived in this work could be helpful in predicting the persistence of phenylureas and of related compounds in natural water.     

Phytotoxicity of four herbicides in different synthetic soils

The relative phytotoxicity of four soil-applied herbicides, benzthiazuron, cycloate, delachlor, and pyrazon, used for sugar beet (Beta vulgaris L.), was tested on a dilution series of peat, Newe Ya’ar clay soil and Hamadia calcareous clay soil mixed with sand, and of Newe Ya’ar clay soil mixed with lime. The phytotoxicity was assessed with oats (Avena sativa L. cv. Mulga). Cycloate was the most potent herbicide of the four, except in soils with high organic matter ( ?11%), where delachlor was more active. Benzthiazuron was the least phytotoxic herbicide in the peat + sand mixtures, but it was more active than pyrazon in lighter soils of the Newe Ya’ar series. The addition of sand to the peat and the soils increased the phytotoxicity of all herbicides. The addition of lime to Newe Ya’ar clay soil decreased the phytotoxicity of benzthiazuron and pyrazon but not of delachlor.     

除草剂土壤处理对绿豆生长发育及产量的影响

试验采用了单因素随机区组设计,研究了四种土壤处理除草剂单用及混用对绿豆的安全性。通过测定绿豆的出苗率、光合速率、蒸腾强度、气孔导度、产量等与生长发育相关的形态和生理指标,结果表明,50%乙草胺750 m l/667m2 50%速收150 g/667m2对绿豆安全并有较好的增产效果。     

4种茎叶处理除草剂对半夏田杂草的防除效果

为有效解决半夏田草害问题, 选择4种茎叶除草剂进行半夏田杂草防除田间药效试验。结果表明:10%乙羧氟草醚EC 50~60 mL/667m2 (制剂用量,下同)处理与240 g/L乳氟禾草灵EC 20~30 mL/667m2处理能有效防除半夏田金腰箭、辣子草、土荆芥、金荞麦、紫花香薷、针筒菜、尼泊尔蓼等阔叶杂草, 且对半夏安全, 药后21 d对阔叶杂草株防效、鲜重防效均达90%以上, 与禾本科除草剂8.8%精喹禾灵EC 40 mL/667m2或108 g/L高效氟吡甲禾灵EC 30 mL/667m2搭配使用对半夏田大部分杂草能实现较好防除。但两种阔叶除草剂持效期较短(30 d左右), 生产上可根据施药后期田间杂草发生情况, 采用人工拔除或进行第2次化学防除; 施药应避开中午高温时刻, 以免造成此类阔叶除草剂药害。研究结果可为半夏田除草剂的合理选择和应用提供科学依据。     

Adsorption and degradation of four acidic herbicides in soils from southern Spain

BACKGROUND: Pesticide degradation and adsorption in soils are key processes determining whether pesticide use will have any impact on environmental quality. Pesticide degradation in soil generally results in a reduction in toxicity, but some pesticides have breakdown products that are more toxic than the parent compound. Adsorption to soil particles ensures that herbicide is retained in the place where its biological activity is expressed and also determines potential for transportation away from the site of action. Degradation and adsorption are complex processes, and shortcomings in understanding them still restrict the ability to predict the fate and behaviour of ionisable pesticides. This paper reports the sorption and degradation behaviour of four acidic pesticides in five soils from southern Spain. Results are used to investigate the influence of soil and pesticide properties on adsorption and degradation as well as the potential link between the two processes. RESULTS: Adsorption and degradation of four acidic pesticides were measured in four soils from Spain characterised by small organic matter (OM) contents (0.3-1.0%) and varying clay contents (3-66%). In general, sorption increased in the order dicamba < metsulfuron-methyl < 2,4-D < flupyrsulfuron-methyl-sodium. Both OM and clay content were found to be important in determining adsorption, but relative differences in clay content between soils were much larger than those in OM content, and therefore clay content was the main property determining the extent of herbicide adsorption for these soils. pH was negatively correlated with adsorption for all compounds apart from metsulfuron-methyl. A clear positive correlation was observed for degradation rate with clay and OM content (P < 0.01), and a negative correlation was observed with pH (P < 0.01). The exception was metsulfuron-methyl, for which degradation was found to be significantly correlated only with soil bioactivity (P < 0.05). CONCLUSIONS: Both OM and clay content were found to be important in determining adsorption, but relative differences in clay content between soils were much larger than those in OM content, and therefore clay content was the main property determining the extent of herbicide adsorption for soils of this type. pH was negatively correlated with adsorption for all compounds apart from metsulfuron-methyl. The contrasting behaviour shown for these four acidic pesticides indicates that chemical degradation in soil is more difficult to predict than adsorption. Most of the variables measured were interrelated, and different behaviours were observed even for compounds from the same chemical class and with similar structures.     

Effects of various classes of herbicides on four species of algae

Chlorella pyrenoidosa, Chlorococcum sp., Lyngbya sp., and Anabaena variabilis were cultured in Bold's basal medium. They were treated with 0.1, 1.0, and 10 μM concentrations of 2-chloro-2′, 6′-diethyl-N-(methoxymethyl)acetanilide (alachlor), 2-chloro-4-(ethylamino)-6-(tert-butyl-amino)-s-triazine (terbuthylazine), 2-sec-butyl-4,6-dinitrophenol (dinoseb), 1,1-dimethyl-3-(α,α,α-trifluoro-2,6-dinitro-N-propyl-p-toluidine) (profluralin), 2, 4-bis(isopropylamino)-6-(methylthio)-s-triazine (prometryne), and (2,4-dichlorophenoxy)acetic acid (2,4-D). Growth of all algal species tested was markedly reduced by the triazines. Alachlor, dinoseb, and fluometuron inhibited growth of some algae at higher concentrations while 2,4-D and profluralin did not inhibit growth at the concentrations tested. Photosynthesis was greatly inhibited by the triazines, even at the 0.1 μM concentration. Fluometuron was very toxic to the blue-green algae but had less effect on the green algae tested. Lyngbya was most susceptible to photosynthesis reduction by the herbicides. The concentrations of herbicides tested had little effect on respiration of the algae species. It appears that effects on algal growth were due primarily to inhibition of photosynthesis rather than to other metabolic processes.     

Mobility and persistence of four herbicides in soil of a South Australian vineyard

The use of persistent herbicides has increased the potential for contamination of soil, soil water and groundwater. The mobility, dissipation and fate of four herbicides, norflurazon, oxadiazon, oxyfluorfen and trifluralin, used in South Australian viticulture, have been studied in a typical sand‐over‐clay vineyard soil. Following herbicide application at field rates to plots up‐slope of miniature lysimeters, surface soil and soil water were sampled regularly over the period of annual rainfall. The concentration of each herbicide in the soil cores, surface soil and soil water was determined by GLC‐NPD following solid‐phase concentration procedures where necessary. Oxadiazon dissipated more quickly than the other three herbicides in the soil. Norflurazon was the most mobile of these herbicides in this soil. However all four herbicides were found in the soil water within the first year, though only norflurazon was found in the soil water in the subsequent year. Norflurazon moved laterally to a greater extent than the other herbicides. © 2000 Society of Chemical Industry     

4种除草剂与助剂安融乐协同防除紫花苜蓿田马唐的研究

为探究高效氟吡甲禾灵?精吡氟禾草灵?烯草酮?精喹禾灵对紫花苜蓿田老根马唐的防除效果及助剂安融乐对上述4种药剂的增效作用, 在室内测定马唐幼苗和成株对4种除草剂及添加助剂的敏感性, 并在田间验证上述4种除草剂与助剂混用对老根马唐的防效?室内结果表明, 成株马唐对高效氟吡甲禾灵?精吡氟禾草灵?烯草酮?精喹禾灵的耐药性增加明显, 其中精喹禾灵的耐药性增加最大; 高效氟吡甲禾灵?精吡氟禾草灵?烯草酮?精喹禾灵与安融乐混配后, 成株马唐的鲜重GR50(有效成分)较单用上述除草剂分别减少16.6%?31.0%?31.5%?6.2%, 其中烯草酮与安融乐混配增效作用最为明显?田间结果表明, 安融乐的加入能提高上述4种除草剂对老根马唐的防效, 其中烯草酮和安融乐混配对老根马唐的增效最优, 株防效和鲜重防效较单用分别增加10.39和8.58百分点, 并显著提高紫花苜蓿产量?     

Spectral and time-resolved fluorescence signature of four weed species as affected by selected herbicides

In the present study we show for the first time the suitability of the laser-induced fluorescence technique to evaluate in vivo herbicide-induced damages as revealed by changes of fluorescence spectra and lifetime. Four herbicides of different modes of action (glyphosate, bromoxynil, mesotrione, and amitrole) were selected and applied to four weed species (Stellaria media, Setaria viridis, Chenopodium album, and Viola arvensis). Modifications of the fluorescence signature depended on the agrochemical – plant species interaction as well as on the time after application. Measurements in the red and far-red spectral region reveal disturbances in the functionality of the photosynthetic apparatus and chlorophyll concentration, e.g. after application of bromoxynil or mesotrione. Recordings in the blue and green spectral regions indicate changes of both amount and composition of specific fluorophores, i.e. after application of glyphosate and amitrole. In all spectral measurements, the position of peak maxima was not affected by herbicide application. The fluorescence lifetime, expressed as LTmean or as lifetime 1 (LT1, short-duration) and LT2 (long-duration) fractions, provided additional information to the spectrally resolved data. Thereby, significant alterations of the lifetime duration and fractional characteristics were observed at specific wavelengths, e.g. after application of bromoxynil, mesotrione, or amitrole.     

Effect of four herbicides and two oils on leaf-cell membrane permeability*†

Leakage of electrolytes from leaf discs of treated Phaseolus Vulgaris L. plants was the main criterion used to study the effect of several chemicals on the permeability of leaf-cell membranes. Paraquat, diquat, dinoseb and oxyfluorfen (2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(Trifluoromethyl) benzene) increased leaf-cell membrane permeability after exposure for 12 h or less. An‘aromatic’oil caused a large increase in permeability at 2–5 min after treatment. Increases in electrolyte release were also correlated with release of soluble amino acids from the leaf discs but the former method was the more sensitive. Increase in cell membrane permeability was always associated with injury symptoms such as appearance of necrotic areas in leaves. Chlorpropham, linuron, sodium azide, glyphosate and 2,4-D at 10^?3M, as well as 1% X-77 surfactant and a non-phytotoxic isoparaffinic oil did not alter leaf-cell permeability at 12 h after treatment. Light was necessary for paraquat and oxyfluorfen to alter leaf cell permeability. Paraquat and oxyfluorfen caused a greater increase in leaf-cell permeability of a soybean mutant with yellow leaves as compared with the normal green leaves. With oxyfluorfen this difference in permeability was greater than with paraquat, and was associated with the appearance of severe necrotic injury symptoms in the yellow mutant; paraquat caused no injury symptoms.     

4种芽前除草剂防除直播小白菜田杂草的效果及其安全性

采用田间试验方法研究了33%二甲戊灵乳油、96%精异丙甲草胺乳油、50%敌草胺水分散粒剂和90%禾草丹乳油4种芽前除草剂防除直播小白菜田杂草效果及其安全性,筛选出了适于直播小白菜田的芽前除草剂。结果表明,药后35d,33%二甲戊灵乳油有效用量371.25~742.5g/hm2、96%精异丙甲草胺乳油864~1 080g/hm2和90%禾草丹乳油1 687.5~2 025g/hm2处理无论是总草株防效还是鲜重防效均在94.27%以上,其次是50%敌草胺水分散粒剂750~1 500g/hm2处理,防效为85.62%~90.54%。33%二甲戊灵乳油各供试剂量虽对小白菜的出苗没有影响,但对小白菜的生长有一定影响,表现为地上部株高和鲜重受抑制;其他3个供试除草剂各剂量处理对小白菜出苗和生长安全。从除草效果和安全性两方面综合考虑,推荐96%精异丙甲草胺乳油864~1 080g/hm2和90%禾草丹乳油1 687.5~2 025g/hm2用于小白菜田芽前防除杂草。     

四种除草剂不同施药时期对冬小麦田杂草的防除效果

通过对巨星等四种麦田除草在冬前（小麦越冬前）和春季（小麦拔节前）不同施药时间的除草试验，结果表明同一种除草剂品种在冬前适期用药除草效果明显优于春季用药，防效较春季施药可提高10％－20％     

甘肃省枸杞炭疽病菌对4种甾醇脱甲基抑制剂的敏感性

为明确甘肃省枸杞炭疽病菌对甾醇脱甲基抑制剂类药剂 (DMIs) 的敏感性,采用菌丝生长速率法测定了采自甘肃省靖远县3个地区及景泰县3个地区共102株枸杞炭疽病菌对苯醚甲环唑、戊唑醇、丙环唑及氟硅唑的敏感性,分别就不同年份、不同地区间胶孢炭疽复合种和尖孢炭疽复合种对4 种 DMIs 杀菌剂的敏感性差异进行了分析。结果表明:供试46 株枸杞胶孢炭疽复合种整体上对苯醚甲环唑、戊唑醇、丙环唑和氟硅唑仍表现为敏感,EC₅₀值分别在0.28~1.20、0.11~2.98、0.32~2.84和0.35~3.85 μg/mL之间;而56株尖孢炭疽复合种对4种药剂的敏感性则出现了不同程度分化,部分菌株疑似已出现敏感性下降现象,其中,对苯醚甲环唑、戊唑醇、丙环唑和氟硅唑敏感性最低的菌株EC₅₀值分别为1.63、3.80、6.21和4.74 μg/mL。不同年份间采集的枸杞胶孢炭疽复合种和尖孢炭疽复合种对4种杀菌剂的敏感性均存在显著差异,2017年采集的菌株敏感性相对更低,4种杀菌剂对胶孢炭疽复合种的平均EC₅₀值分别为 (0.84 ± 0.03)、(1.23 ± 0.13)、(1.19 ± 0.09) 和 (1.69 ± 0.17) μg/mL,对尖孢炭疽复合种的平均EC₅₀值分别为 (1.06 ± 0.03)、(2.25 ± 0.15)、(2.43 ± 0.20) 和 (2.85 ± 0.19) μg/mL。不同地区枸杞炭疽病菌对4种杀菌剂的敏感性表现不同,其中靖远县五合镇的胶孢炭疽复合种对4种杀菌剂敏感性最低,平均EC₅₀值分别为 (0.79 ± 0.12)、(1.28 ± 0.87)、(1.39 ± 1.05) 和 (1.74 ± 1.04) μg/mL,景泰县草窝滩镇的胶孢炭疽复合种对苯醚甲环唑和丙环唑敏感性最高,平均EC₅₀值为 (0.28 ± 0.10) 和 (0.46 ± 0.10) μg/mL,对戊唑醇和氟硅唑敏感性最高的胶孢炭疽复合种来自景泰县寺滩乡,平均EC₅₀值为 (0.42 ± 0.16) 和 (0.65 ± 0.09) μg/mL;不同地区间采集的尖孢炭疽复合种对4种杀菌剂的敏感性则不存在显著差异。研究结果可为甘肃省枸杞炭疽病防治中杀菌剂的合理使用及延缓抗药性发展提供依据。     

表面活性剂辅助-凝固-漂浮分散液-液微萃取-高效液相色谱法检测葡萄酒中4种三嗪类除草剂残留

建立了表面活性剂辅助-凝固-漂浮分散液-液微萃取-高效液相色谱(SA-DLLME-SFO-HPLC)法检测葡萄酒中西玛津、莠去津、特丁津和扑草净4种三嗪类除草剂残留的分析方法。考察了萃取剂的类型、萃取剂和表面活性剂的体积、萃取时间和盐效应等对萃取效率的影响,确定最佳萃取条件为:20 μL十一醇作为萃取剂,2 μL 0.25 g/L的Tween-20水溶液作为分散剂,萃取时间10 min,氯化钠的质量浓度为250 g/L。结果表明:西玛津、莠去津、特丁津和扑草净的线性范围为0.008~5 mg/L,检出限分别为2.4、1.8、2.0和2.8 μg/L,富集倍数在24.5~32.4之间。在0.008、0.08和2.4 mg/L添加水平下,西玛津、莠去津、特丁津和扑草净在葡萄酒中的回收率在84%~102%之间,相对标准偏差(n=5)在2.1%~6.9%之间。该方法可用于葡萄酒中西玛津、莠去津、特丁津和扑草净残留量的测定。     

Efficacy of four corn (Zea mays L.) herbicides when applied with flat fan and air induction nozzles

Twelve field experiments were conducted over a 4 year (2002–2005) period to determine the influence of the herbicide dose, nozzle type, spray volume, and spray pressure on herbicide efficacy in field corn ( Zea mays L.). The control of Abutilon theophrasti (velvetleaf ), Ambrosia artemisiifolia (common ragweed), Chenopodium album (common lambsquarters), Amaranthus powellii (green pigweed), and Echinochloa crus-galli (barnyard grass) was improved with the use of full herbicide doses compared to half doses of bromoxynil, glufosinate, dicamba, and nicosulfuron. The yield was increased for bromoxynil, glufosinate, and nicosulfuron when the full herbicide dose was used. When applied at the manufacturer's recommended dose, flat fan nozzles, compared to air induction (AI) nozzles, provided better control of A. theophrasti , A. artemisiifolia , and C. album with bromoxynil, A. artemisiifolia and C. album with dicamba, and E. crus-galli with nicosulfuron. Bromoxynil, in relation to weed control, was the only herbicide that was affected by the water carrier volume. By increasing the spray pressure with an AI nozzle, there was an improvement in the control of A. theophrasti , A. artemisiifolia, and C. album with the application of bromoxynil and E. crus-galli with the application of nicosulfuron, with a yield increase with bromoxynil. Overall, this study concludes that the optimum nozzle type, water carrier volume, and spray pressure is herbicide- and weed species-specific.     

基于登记用量分析我国四大主粮作物田除草剂的登记现状

为除草剂合理减施提供数据参考,本研究于2019年7月3日自中国农药信息网查询我国四大主粮作物——小麦、水稻、玉米和马铃薯登记的除草剂,并对这4种作物田登记除草剂单剂（含原药）及混剂的条目数量进行整体分析,并对所有单剂有效成分以及不同剂型的登记条目数量进行分析,筛选出高用量单剂有效成分,分别从剂型和防治对象上进行用量分析,再将用量最高的4种有效成分、3种作物和3种防治对象进行组合,对已登记的组合进行用量分析。结果显示：有效成分用量最大值、均值和范围排序均依次为水稻田、小麦田、玉米田和马铃薯田,并选出15种高用量单剂有效成分,其中2甲4氯钠、2,4-滴钠盐、苯磺隆、丙草胺、丁草胺、2,4-滴二甲胺盐和2甲4氯二甲胺盐等存在用量差异大、异常高值点多的问题;登记除草剂单剂有效成分用量最高的剂型为可溶粉剂,用量最高的防治对象为阔叶杂草和莎草科杂草;2甲4氯钠-水稻-阔叶杂草和2甲4氯钠-水稻-莎草科杂草组合用量差异大且离群高值点多,究其原因可能与剂型、厂家有关。为减少除草剂用量,建议在最低有效剂量研究基础上,选择有效成分用量较低的除草剂品种。