新型土壤熏蒸剂二甲基二硫研究进展

采用熏蒸剂进行土壤消毒可有效控制设施作物及高附加值作物的土传有害生物,其中熏蒸效果突出的熏蒸剂溴甲烷由于会破坏臭氧层而被禁用,导致土传有害生物熏蒸治理过程中缺乏高效稳定的熏蒸产品。二甲基二硫是一种新型熏蒸剂,对有害线虫具有高活性,可兼治部分土传病原菌及杂草。广谱、安全和高效等优点使其成为最有推广应用前景的溴甲烷替代药剂,或将改善国内杀线虫熏蒸剂缺乏的局面。该文系统综述了国内外关于二甲基二硫对土传有害生物的防控活性、作用机制和降解、散发逃逸、扩散分布及残留等环境行为,以及对土壤养分、微生物及非靶标生物等方面的影响,以期为二甲基二硫的开发及推广应用提供参考。     

美国土壤熏蒸剂使用风险管理措施

概述了美国土壤熏蒸剂登记和应用情况,介绍了美国为降低土壤熏蒸剂使用风险所采取的措施。结合我国土壤熏蒸剂登记及使用实际,提出了加强我国农药使用管理、降低使用风险的措施。     

微生物菌肥对熏蒸剂处理后土壤微生态的影响研究进展

土壤熏蒸是防治土传病害的有效手段,但化学熏蒸剂在杀死病原微生物的同时也会对有益微生物群落的组成与活性造成影响。微生物菌肥不仅能够减少农作物的病虫害侵染,而且能够改善农产品的品质与产量。将土壤熏蒸剂与微生物菌肥配合使用将有利于连作土壤修复、土壤-植物微生态环境的改良与重塑。一方面,土壤熏蒸剂用于消灭前茬作物遗留下的土壤病原物,给土壤进行消毒处理;另一方面,施用微生物菌肥给“纯净”的土壤环境输入有益菌群,引导更利于植物生长的土壤微生态环境(土壤理化性质、土壤微生物群落结构)形成。本文简述了土壤熏蒸剂、微生物菌肥以及微生物菌肥介入熏蒸后的土壤对土壤理化性质、土壤酶系及土壤微生物群落变化的研究进展,旨在系统解析微生物菌肥对经熏蒸剂处理后土壤微环境变化的影响,以期为解决连作障碍、防治土传病害、恢复植物根际功能提供相关理论与技术参考。     

熏蒸剂的使用现状与研究进展

熏蒸剂是在一定温度和压力条件下,能产生对有害生物具有防治作用的气体的一类化学物质。在常温常压下,它们中有些种类是以气体状态存在的,而有些种类则需经过某些化学反应或增加温度后才能产生这种气体。熏蒸剂具有以下特征：1、在一定温度和施用条件下,对昆虫具有杀虫活性;2、一般不易燃,不爆炸;3、施用方便;4、与室内物品不发生化学反应,不具腐蚀性;5、被吸附的量相对较小;6、能迅速穿透被处理物,发散速度快等。     

土壤熏蒸剂对生姜土传病害的防治效果和产量的影响

土传青枯病和茎基腐病对生姜的危害严重制约了生姜产业的可持续发展,土壤熏蒸消毒方法对土传病害有较好的防治效果.本文以氯化苦和棉隆两种土壤熏蒸剂为研究对象,探究其对生姜青枯病和茎基腐病的防治效果及其对生姜产量的影响.结果表明,氯化苦和棉隆处理土壤揭膜后第7天定植的带芽种姜无药害,姜芽生长正常;与对照相比,氯化苦和棉隆处理均...     

基于室内土柱模拟的5种土壤熏蒸剂散发特征

土壤熏蒸是防治土传病虫害的重要手段之一, 熏蒸剂在土壤中的散发直接影响其对土壤有害生物的防治效果。为明确二甲基二硫、顺式-1, 3-二氯丙烯、反式-1,3-二氯丙烯、异硫氰酸烯丙酯, 以及棉隆和威百亩的前体异硫氰酸甲酯等5种常用熏蒸剂在土壤中的散发情况, 本研究以北京顺义采集的沙壤土为材料, 按100 mg/kg剂量添加熏蒸剂, 在室内模拟田间熏蒸剂在土壤内的散发, 并在不同温度(15、25、35℃)和不同土壤含水量(6%、10%、15%)等条件下分别对5种熏蒸剂的散发进行监测。同时拟合出5种熏蒸剂的累计散发量随时间变化的Logistic模型, R2均高于0.98, 拟合度较好。本研究为熏蒸剂的合理化利用、减少农药滥用、减轻环境压力提供一定参考。     

农药在土壤中的环境行为

本文阐述了农药在土壤中的环境行为,即农药的漂移、挥发和光解;农药的动、植物吸收;农药的地表径流;农药的土壤滞留和吸附;农药的土壤淋溶;农药的生物、非生物降解。作者根据自己的研究结果,讨论了农药的土壤环境行为与土壤理化特性及与农药理化特性的关系,并对农药非点源污染的治理问题提出建议。     

四种熏蒸剂对辣椒疫霉和南方根结线虫的毒力

为明确不同熏蒸剂对土传病原菌辣椒疫霉Phytophthora capsici和南方根结线虫Meloidogyne incognita的毒力,采用密闭熏蒸法测定了4种土壤熏蒸剂氯化苦、棉隆、威百亩、1,3-二氯丙烯的毒力及1,3-二氯丙烯和氯化苦复配的联合毒力。结果表明:氯化苦、棉隆、威百亩、1,3-二氯丙烯对辣椒疫霉的EC₅₀分别为0.12、2.44、8.30、8.45 mg/L; 对南方根结线虫的EC₅₀ 分别为1.23、0.22、0.30、0.18 mg/L。1,3-二氯丙烯和氯化苦以2:1、1:1、1:2比例复配时对辣椒疫霉的EC₅₀ 分别为1.13、0.24、0.14 mg/L;对南方根结线虫的EC₅₀分别为0.19、0.32、0.61 mg/L。结合经济效益和多种病害兼治的原则,推荐使用1,3-二氯丙烯与氯化苦1:1配比,可兼治辣椒疫病和根结线虫病。     

土壤熏蒸剂棉隆防治土传病害研究进展及未来发展趋势

棉隆对病原细菌、真菌、根结线虫及杂草均有较高防效,而且作为固体微颗粒剂具有使用简单、安全的特性,被广泛用于作物种植前熏蒸土壤以防治土传病虫害。施用过程中,土壤环境因素（包括土壤类型、土壤温湿度、土壤有机质及pH等）、施药方式、施药季节和施药剂量均会对棉隆的熏蒸效果产生显著影响,不正确的使用方式常会导致熏蒸效果不理想或产生药害问题。该文系统综述土壤熏蒸剂棉隆的使用概况（包括作用机制、适用作物、施用方式和施用效果等）、存在的问题及原因分析（包括施用深度、水分、温度对棉隆有效成分含量的影响及其熏蒸对土壤微生物群落结构的影响等）、解决对策（包括改善施药方式、优化土壤环境和活化熏蒸后土壤微生物等）以及未来发展趋势,以期为棉隆的高效应用提供借鉴。     

减少土壤熏蒸气体散发的措施研究进展

本文综述了可减少土壤熏蒸防治土传有害生物过程中熏蒸气体散发的几种物理及化学方法研究进展,如覆盖塑料薄膜、增加施药深度、增加土壤含水量、提高土壤容重、添加生物炭、采用滴灌系统施药、研发新剂型以及向土壤表面添加有机和无机肥料等。虽然采用上述单一方法均能够不同程度减少熏蒸气体的散发损失,但是将多种技术联合使用能达到更理想的减排效果。同时建议相关政府管理部门、科研人员和种植者共同努力,将除覆盖塑料薄膜外的其他替代减排技术推广应用到实际生产中,以达到减少熏蒸气体排放效果的同时减少塑料薄膜的使用,降低对生态环境的不利影响。     

Characterization of propargyl bromide transformation in soil

Propargyl bromide is being investigated for its potential as a soil fumigant. Characterization of the fate of propargyl bromide in soil is important in determining both efficacy and the threat of environmental contamination. These experiments investigated some of the factors affecting the rate of propargyl bromide degradation in soil and quantified some of the products formed as a result of propargyl bromide degradation in four soils of differing composition and at three initial propargyl bromide concentrations. In all soils at all initial propargyl bromide concentrations, equimolar formation of Br- was observed during propargyl bromide degradation, but little propargyl alcohol (product of hydrolysis) was formed. The apparent first-order degradation coefficient (k) increased with decreasing initial propargyl bromide concentration in all soils, but the mass degraded per unit time increased with increasing propargyl bromide concentration. The rate of propargyl bromide degradation increased with increasing soil organic matter content, and the k value was correlated to the organic carbon content of the soil (correlation coefficient > 0.97 for all concentrations). Repeated application of propargyl bromide did not increase the rate of propargyl bromide degradation in soil. Addition of Br- did not affect the rate of propargyl bromide transformation in soil, so accumulation of Br- in the soil is not expected to impede propargyl bromide degradation.     

Permeation of soil fumigants through agricultural plastic films

Plastic films are used in soil fumigation to control fumigant emission into the atmosphere. In previous studies it was shown that the plastic films are permeable to fumigant vapors. Virtually impermeable films (VIF) have been developed to reduce such emission and to increase the efficacy of pest control. A rapid, accurate, sensitive and simple method to measure the permeability of plastic films to soil fumigants that was developed in the present study is described in this paper. The method uses a static, closed system in which the tested film is fixed between two cells. The fumigant is sampled by a solid-phase microextraction method and measured quantitatively by gas chromatography. The method was used to assess the permeability of two plastic films — a low-density polyethylene film (LDPE) and a VIF — to commercial soil fumigants formulated individually or in mixtures. All the tested fumigants permeated through the commonly used LDPE film, in the following descending order of permeability: methyl isothiocyanate (MITC), methyl bromide (MBr), 1,3-dichloropropene (1,3-D; Telone), chloropicrin (CP). The VIF was impermeable to all the tested fumigants except MITC, the permeation of which was reduced by 40%. The permeation of some fumigants through LDPE films was influenced by the formulation used. The permeation of CP was increased when it was combined with MBr in Bromopic. With Telopic, a mixture of 1,3-D and CP, the permeation of 1,3-D through LDPE film was 62% greater than that of Telone, whereas that of CP was not affected. The permeation rates of both MBr and CP were 25–30% greater when they were formulated as a mixture in Bromopic than when they were formulated individually. The formulation of fumigants as mixtures of two components did not affect their permeability through VIF. This study showed that differences in the suitability of plastic films for soil fumigation can be measured easily in a laboratory. It also showed that the VIP was more effective than LDPE in reducing losses of fumigant to the atmosphere, thus allowing more efficient use of fumigants to manage soilborne pests. The presented method helps us to choose the most adequate film for optimizing fumigation efficacy, and reducing costs and environmental risks. http://www.phytoparasitica.org posting Sept. 17, 2006.     

Diffusion and emissions of 1,3-dichloro propene in Florida sandy soil in microplots affected by soil moisture, organic matter, and plastic film

The main objective of this study was to determine the influence of soil moisture, organic matter amendment and plastic cover (a virtually impermeable film, VIF) on diffusion and emissions of (Z)- and (E)-1,3-dichloropropene (1,3-D) in microplots of Florida sandy soil (Arredondo fine sand). Upward diffusion of the two isomers in the Arredondo soil without a plastic cover was greatly influenced by soil-water content and (Z)-1,3-D diffused faster than (E)-1,3-D. In less than 5 h after 1,3-D injection to 30 cm depth, (Z)- and (E)-1,3-D in air dry soil had diffused to a 10 cm depth, whereas diffusion for the two isomers was negligible in near-water-saturated soil, even 101 h after injection. The diffusion rate of (Z)- and (E)-1,3-D in near-field-capacity soil was between the rates in the two water regimes. Yard waste compost (YWC) amendment greatly reduced diffusion of (Z)- and (E)-1,3-D, even in air-dry soil. Although upward diffusion of (Z)- and (E)-1,3-D in soil with VIF cover was slightly less than in the corresponding bare soil; the cover promoted retention of vapors of the two isomers in soil pore air in the shallow subsurface. More (Z)-1,3-D vapor was found initially in soil pore air than (E)-1,3-D although the difference declined thereafter. As a result of rapid upward movement in air-dry bare soil, (Z)- and (E)-1,3-D were rapidly volatilized into the atmosphere, but emissions from the near-water-saturated soil were minimal. Virtually impermeable film and YWC amendment retarded emissions. This study indicated that adequate soil water in this sandy soil is needed to prevent rapid emissions, but excess soil water slows diffusion of (Z)- and (E)-1,3-D. Thus, management for optimum water in soil is critical for pesticidal efficacy and the environment.     

Physical, chemical and environmental properties of selected chemical alternatives for the pre-plant use of methyl bromide as soil fumigant

Production and use of methyl bromide, a soil fumigant, are being restricted because of this chemical's deleterious effects on stratospheric ozone concentrations. Several products, some of which are currently used as soil fumigants, are being considered as possible replacements for methyl bromide, alone and in various combinations. Among these, 1,3-dichloropropene, methyl isothiocyanate generators such as metam-sodium, and chloropicrin are currently registered, while others such as methyl iodide and sodium azide are at different stages of the registration process. This review examines physicochemical properties, environmental fate, and metabolism of the various potential methyl bromide replacement products.     

氯化苦熏蒸对土壤反硝化作用及nirS型反硝化细菌群落结构的影响

探究氯化苦熏蒸对土壤反硝化作用的影响及机制。采用理化分析和DGGE方法分析了氯化苦熏蒸后土壤反硝化及nirS型反硝化细菌群落结构。不同浓度氯化苦熏蒸对土壤nirS型反硝化细菌群落均匀度无影响,而对nirS型反硝化细菌多样性和丰富度指数的影响为高浓度中浓度低浓度对照。对土壤反硝化作用的影响表现为,经500 mg/kg氯化苦熏蒸的土壤在培养初期(0 d)反硝化率比对照降低10.55%,土壤反硝化作用被显著抑制。2周后3种浓度氯化苦均抑制土壤反硝化作用, 4周后土壤的反硝化作用缓慢恢复。500 mg/kg浓度氯化苦对土壤反硝化强度的影响与nirS型反硝化细菌群落结构变化不同,说明土壤反硝化作用的强弱并非完全决定于土壤nirS型反硝化细菌。