溴甲烷在番茄土壤消毒中替代技术研究

采用保护地内划分小区实验方法，在番茄载培过程中，研究了代替溴甲烷的其它3种消毒技术，结果表明，生物熏蒸，人工基质和阿维菌素对防治根结线虫都有不同的效果，增产幅度分别为18．9％，14．05％，19．0％，同时嗅甲烷土壤消毒增产22．06％。从直接经济效益看，阿维菌素＞生物熏蒸＞溴甲烷＞人工基质。     

Surface water seal application to minimize volatilization loss of methyl isothiocyanate from soil columns

BACKGROUND: Metam‐sodium (MS, sodium methyldithiocarbamate) has been identified as a promising alternative chemical to replace methyl bromide (MeBr) in soil preplant fumigation. One degradation product of MS in soil is the volatile gas methyl isothiocyanate (MITC) which controls soilborne pests. Inconsistent results associated with MS usage indicate that there is a need to determine cultural practices that increase pest control efficacy. Sealing the soil surface with water after MS application may be a sound method to reduce volatilization loss of MITC from soils and increase the contact time necessary for MITC to control pests. The objective of this research was to develop a preliminary soil surface water application amount that would potentially inhibit the off‐gassing rate of MITC. RESULTS: Off‐gassing rate was consistently reduced with increasing water seal application. The application of a 2.5–3.8 cm water seal provided significantly lower (71–74% reduction in MITC volatilization) total fumigant loss compared with no water seal. The most favorable reduction in MITC off‐gassing was observed in the 2.5 cm water seal. CONCLUSION: This suggests that volatilization of MITC‐generating compounds can be highly suppressed using adequate surface irrigation following chemical application in this soil type (sandy clay loam), based on preliminary bench‐scale soil column studies. Copyright © 2010 Society of Chemical Industry     

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.     

Effect of soil physical factors on methyl iodide and methyl bromide

Production and importation of methyl bromide is scheduled to be banned by 2001. Methyl iodide was evaluated as a possible replacement soil fumigant. The effects of soil moisture, temperature, soil texture and fumigation time on the efficacy of methyl iodide for the control of two common weeds, Abutilon theophrasti and Lolium multiflorum, were characterized and compared with those of methyl bromide. The optimal soil moisture for methyl iodide to kill both weed species in sandy soils was 14% water content (w/w). Greater efficacy was obtained when the temperature during fumigation was above 20°C. Compared to methyl bromide, the efficacy of methyl iodide was more consistent in different soils. Time to 100% mortality of weeds was 24 h for methyl iodide fumigation and 36 h for methyl bromide when 200 μM of fumigant was used. On a molar basis methyl iodide was consistently more effective than methyl bromide across the range of environmental factors tested. In terms of application technology and spectrum of activity, methyl bromide can be directly replaced by methyl iodide. © 1998 SCI     

溴甲烷土壤消毒替代技术研究进展

概述了溴甲烷替代品的新进展。在土壤消毒方面,新的进展有化学替代品:氯化苦胶囊、氯化苦乳剂、氯化苦+噻唑磷混用、C₂N₂、氰铵化钙、异硫氰酸烯丙酯、异硫氰酸甲酯、1,3—二氯丙烯和氯化苦混剂、碘甲烷、环氧丙烷、叠氮化合物、硫酰氟等。在使用技术上,采用化学灌溉和注射施药技术进一步提高药剂分布的均匀性。在非化学替代技术上,生物熏蒸和有机质补充正受到重视。减少溴甲烷的技术正在快速地发展。     

Photodegradation of bensulfuron-methyl on soil surface

Photolysis of bensulfuron-methyl on soil surface was studied under sunlight and UV light. Seven photoproducts were isolated and characterised by spectroscopic methods. The major processes in the photolysis of bensulfuron-methyl in soil are cleavage of the sulfonylurea bridge, scission of the SO2NH bond and contraction of the sulfuronylurea bridge. The rates of photodegradation of bensulfuron-methyl on different soils followed first-order rate kinetics with half lives of 21.9, 28.4, 36.9, 59.2 and 47.2 h (UV) and 23.1, 27.5, 29.1, 38.9 and 33.8 days (sunlight) for vertisol, alluvial, alfisol, red and laterite soils, respectively. The differences in rates of photodegradation were dependent upon the soil texture and organic matter content.     

Evaluation of methyl iodide as a soil fumigant in container and small field plot studies

Methyl iodide was evaluated as a soil fumigant as a potential replacement for the widely used soil fumigant methyl bromide. In container trials, methyl iodide was significantly more effective than methyl bromide against the plant parasitic nematodes Meloidogyne incognita, Heterodera schachtii and Tylenchulus semipenetrans and the plant pathogenic fungus Rhizoctonia solani. In small field plots, soil populations of root-knot nematodes were no longer detected after methyl iodide fumigation at an application rate of 112 kg ha^-1. However, after growing a susceptible lima bean host for two months, substantial root-knot galling occurred, while Rhizobium nodulation was absent. At 168 kg ha^-1 of methyl iodide, root-knot galling was reduced to less than 1%, and no Pythium propagules were recovered on selective detection media. These efficacy data support the conclusion that methyl iodide is a likely candidate for replacing methyl bromide as a soil fumigant. © 1998 SCI.     

生物熏蒸——环境友好型土壤熏蒸技术

根据"蒙特利尔议定书"要求,防治土传病害效果优异的溴甲烷已于2015年全面退出农业领域(除必要用途豁免外),环境友好型的生物熏蒸技术作为最具发展前景的溴甲烷非化学替代措施而受到普遍关注。文章主要综述了生物熏蒸的作用机理:产生挥发性活性物质及提高土壤温度;介绍了生物熏蒸对腐霉菌、疫霉菌、尖孢镰刀菌等土传病害以及线虫的防治作用;同时阐述了生物熏蒸对土壤中氮(N)、磷(P)、钾(K)、pH值等土壤理化性质以及作物生长指标和产量的影响,阐明了生物熏蒸材料的选择以及施用熏蒸材料时的环境条件是影响生物熏蒸效果的两个主要因素。作者认为,由于受生物熏蒸材料自身的限制,目前将生物熏蒸技术与其他技术相结合,如生物熏蒸与化学熏蒸轮用等,依然具有广阔的研究应用前景。     

实验室条件下威百亩及异硫氰酸甲酯在土壤中的降解特性

在实验室条件下,利用高效液相色谱研究了威百亩及其降解产物异硫氰酸甲酯在土壤中的降解特性及影响因素。结果表明:威百亩在土壤中的降解与土壤绝对含水量、环境温度和土壤有机质含量均密切相关。25 ℃下,威百亩在绝对含水量为0、20%、40%、60%的土壤中的半衰期分别为5.0、1.2、4.1和4.3 d,绝对含水量约为20%的土壤最有利于其降解。威百亩的降解速率还随温度的升高和土壤有机质含量的增加而加快。异硫氰酸甲酯的降解趋势与威百亩基本相同。研究结果可为威百亩的田间安全、合理施用提供参考。     

Multivariate analysis of toxicological and environmental properties of soil nematicides

BACKGROUND: In intensive agriculture, the use of pesticides and soil fumigants is necessary to produce economically viable crops worldwide. However, this practice may involve undesirable effects on human health and the environment. In 1995, methyl bromide was restricted by the Montreal Protocol because of possible ozone depletion. The objective of this study was to compare intrinsic environmental and toxicological properties of 11 active substances with nematicidal properties, some of them recognized as methyl bromide alternatives. RESULTS: Four groups of active substances were discriminated by a series of principal component analyses (PCAs): (a) high toxicity to non-target fauna, humans and animals and medium persistence in the environment (cadusafos, ethoprophos and fenamiphos); (b) high toxicity to humans, animals and non-target fauna and high persistence (carbofuran and fosthiazate); (c) low toxicity to non-target fauna, humans and animals and low persistence (carbosulfan, benfuracarb and oxamyl); (d) low toxicity to humans, animals and non-target fauna and medium persistence in the environment (1,3-dichloropropene, chloropicrin and methyl bromide). CONCLUSION: Evaluating the multiple aspects of toxicological and environmental properties of active substances through PCA is proposed as a helpful tool for initially comparing the complex toxicological behaviour of active substances as plant protection products.     

Applicability of ELISA for determination of metsulfuron‐methyl in soil samples

An immunoassay (ELISA) for analysis of metsulfuron‐methyl was evaluated as a method for quantifying residues in soil. Soil samples were extracted with phosphate buffered saline (PBS), PBS + acetone (80 + 20 by volume) or ammonium carbonate and were analyzed with both ELISA and LC‐MS. A tendency for the ELISA to overstimate the metsulfuron‐methyl content was noted and matrix effects were pronounced, particularly in PBS + acetone or ammonium carbonate extracts. Dilution of extracts before analysis improved the situation but reduced the sensitivity of the assay. Using light standard concentrations it was shown that the extracts in PBS on dilutions exhibited a curve parallel with the standard curve, indicating no significant interference due to matrix effects. A working range of 10–250 ng litre⁻¹ was found for ELISA on this type of extracts. © 2000 Society of Chemical Industry     

我国土壤熏蒸消毒60年回顾

熏蒸剂棉隆和氯化苦于20世纪60年代在我国曾用于棉花黄萎病的防治,由于缺乏施药机械、相关施药标准和方法,加之与国外交流甚少,虽然发现熏蒸剂对土传病害有一定的效果,但一直未形成规模化应用。我国大量使用熏蒸剂进行土壤消毒处理始于20世纪90年代,随着溴甲烷的引进与广泛应用,溴甲烷的替代技术及产品研发,开启了我国土壤熏蒸消毒的新纪元。伴随着土壤消毒技术与理论的不断丰富,新型配套机械装备的成功研发,社会化服务模式的广泛运用,土壤熏蒸消毒在我国进入快速发展时期,大批专业化服务组织应运而生,为我国农作物病虫害的绿色防控、实施乡村振兴战略提供了强有力的技术支撑。该文从土壤熏蒸剂的种类、发展历史、基础理论的建立与阐明3方面综述了我国土壤熏蒸发展情况,并对我国土壤熏蒸消毒未来发展方向提出了展望。     

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.     

Weed suppression by soil steaming in combination with activating compounds

The aim of this study was to determine the weed suppression potential of soil steaming plus activating compounds (KOH or CaO) to boost soil temperature. Different combinations between the compounds and rates were tested in experiments carried out in the field and in a controlled environment. Treatment effects were assessed on field weed vegetation and on seedbank and seedling emergence of three winter ( Alopecurus myosuroides , Matricaria chamomilla and Raphanus raphanistrum ) and four spring annuals ( Amaranthus retroflexus , Echinochloa crus-galli , Fallopia convolvulus and Setaria viridis ), were assessed on field weed vegetation. Neither maximum soil temperature (from 72 to 85°C) nor duration of high temperature in the 3 h following application consistently affected weed suppression. In the field, no significant effects on total weed density were recorded, but there were some significant effects on individual species. The weed seedbank was clearly suppressed by activated steaming: total seedling emergence was inversely related to increasing KOH rates both in the 0–10 and 10–20 cm soil layers, while for CaO the relationship was significant only in the 0–10 cm layer. Winter annuals were more sensitive to KOH than CaO and spring annuals had a more pronounced species-specific response to treatments. There was a strong negative relationship between compound rate and seedling emergence for all species. Alopecurus myosuroides was the most sensitive to the steam-alone treatment (77% reduction), whereas M. chamomilla and E. crus-galli were the least sensitive. Results from this study indicate that the type and rates of activating compounds for soil steaming must be adjusted to the weed community composition.     

甲嘧磺隆和炔草酯对土壤微生物呼吸强度和氮转化的影响

为探究除草剂对土壤微生物的毒性效应,以土壤微生物的呼吸强度和氮转化作为检测指标,分别考察了甲嘧磺隆和炔草酯对红壤、棕壤和潮土中微生物呼吸强度的影响以及对潮土氮转化的影响。结果表明:将供试农药以田间推荐剂量、10倍推荐剂量和100倍推荐剂量施入土壤15 d后,甲嘧磺隆对棕壤微生物表现为呼吸强度抑制作用,对潮土为促进作用,而红壤中除10倍推荐剂量处理组表现出抑制作用外其余两组均表现出促进作用;炔草酯会抑制红壤和棕壤中微生物的呼吸强度,但会促进潮土中微生物的呼吸强度。氮转化试验结果表明:以田间推荐剂量和5倍推荐剂量施入潮土后,甲嘧磺隆在7、14、28、42、56和70 d均能显著促进其硝酸盐含量;炔草酯除28 d时田间推荐剂量处理组的硝酸盐含量显著高于对照组外,其余0、7、14和42 d硝酸盐含量与对照组相比均无显著差异。综上所述,两种除草剂对3种土壤类型微生物的呼吸强度为低毒,对潮土氮转化功能没有长期影响。     

Distribution and efficacy of drip-applied metam-sodium against the survival of Rhizoctonia solani and yellow nutsedge in plastic-mulched sandy soil beds

The effects of metam-sodium application rate on soil residence time, spatial and temporal distributions of methyl isothiocyanate and pest control efficacy were studied in a Georgia sandy soil. Metam-sodium 420 g L(-1) SL was drip applied at rates of 147 and 295 L ha(-1) in plastic-mulched raised beds. Methyl isothiocyanate concentrations in soil air space were monitored from four preselected sites: 10 and 20 cm below the emitter, and 20 and 30 cm laterally away from the emitter at 3, 12, 24, 48, 72, 120 and 240 h after chemigation. A higher rate of metam-sodium application resulted in higher methyl isothiocyanate concentrations in the soil. Highest methyl isothiocyanate concentrations were found at 20 cm below the emitter, and lowest at 30 cm laterally away from the emitter. Methyl isothiocyanate concentrations decreased with time and distance from the emitter. Lower methyl isothiocyanate concentration x time product values at 20 and 30 cm away from the emitter resulted in lower mortalities of Rhizoctonia solani Kühn and yellow nutsedge (Cyperus esculentus L.). The results demonstrated that methyl isothiocyanate can be delivered at lethal doses with drip-applied water downward within the beds. Lateral diffusion of methyl isothiocyanate from the point of application did not reach biologically active concentrations to affect the survival of R. solani or yellow nutsedge. Further studies on the lateral distribution of methyl isothiocyanate in sandy soils are needed to circumvent this limitation.     

Fumigation toxicity of volatile natural and synthetic cyanohydrins to stored-product pests and activity as soil fumigants

Insecticidal fumigation toxicity of natural and synthetic cyanohydrins was evaluated with four stored-product pests: the lesser grain borer, Rhyzopertha dominica (F), the red flour beetle, Tribolium castaneum Herbst, the saw-toothed grain beetle Oryzaephilus surinamensis L, the maize weevil, Sitophilus zeamais (Motsch) and the house fly, Musca domestica L. The fumigation LC50 values were calculated by probit analysis. For house flies, all but one of the cyanohydrins tested were more potent than 1,3-dichloropropene (Telone). Three were as efficacious as chloropicrin. For the lesser grain borer, all cyanohydrins tested were more insecticidal than dichloropropene, and all but one were more potent than chloropicrin. Four were as insecticidal as dichlorvos. The acetate of 1-cyano-1-hydroxy-2-propene (CHP-ace) was also tested in soil for antifungal and antibacterial activity, and inhibition of weed seed germination. CHP-ace reduced the total soil bacterial and fungal counts significantly, and was effective in inhibiting the germination of weed seeds in soil, indicating a broad spectrum of activity as a soil fumigant.     

Analysis of metsulfuron‐methyl residues in wheat field soil: a comparison of HPLC and bioassay techniques

BACKGROUND: Metsulfuron‐methyl is a low‐application‐rate sulfonylurea herbicide that is widely used to control broad‐leaved weeds in wheat. Owing to its persistent nature, its residues may be present at phytotoxic levels for the next crop in rotation. Therefore, a comparative evaluation of HPLC and bioassay techniques was made for the analysis of this herbicide in wheat field soil. RESULTS: Metsulfuron‐methyl was applied to wheat crop at different rates (4, 8 and 12 AI ha^?1) at 28 days after sowing as a post‐emergence application, and the soil was analysed for metsulfuron‐methyl residues by HPLC and lentil seed bioassay techniques. The bioassay was found to be the more sensitive technique. At the recommended rate of application, 4 g AI ha^?1, the bioassay technique could detect the residue up to 30 days in surface soil, while, with HPLC, residues were not detectable on the 15th day. The half‐lives of metsulfuron‐methyl by HPLC and bioassay were calculated as 6.3–7.8 and 17.5 days respectively. Under field conditions, residues of metsulfuron‐methyl were also detected in subsurface soil by the bioassay technique at trace levels, but were not detected by the solvent extraction/HPLC method. CONCLUSION: Lentil seed bioassay is a more sensitive technique than HPLC. Traces of residues detected in subsurface soil indicated the mobility of metsulfuron‐methyl into lower layers. Copyright © 2009 Society of Chemical Industry