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1.
A simulation model is described for the transport of the fumigant, methyl bromide gas, away from injection chisels within the field. The injected methyl bromide is assumed to form cylindrical, parallel sources at the depth of injection. Transport of the methyl bromide is described by radial diffusion from the injection cylinders. The dissolution-distillation of methyl bromide gas in the soil water and on soil particles is accounted for by a first-order reversible kinetic equation or by an equilibrium relationship. The hydrolysis of methyl bromide gas to bromide anion is considered to occur according to a first-order irreversible equation. The model considers cases where the soil surface is and is not covered with an impermeable barrier to the diffusion of the gas. Simulated methyl bromide concentrations in the soil air, and bromide concentrations in the soil, compared reasonably well with measured values from several field sites. Comparison of the results of calculations, with and without plastic barriers at the soil surface, with experimental data, indicate that plastic barriers are ineffective in preventing diffusion of gas from the soil to the atmosphere. Calculations of mass balances show that as much as 70% of the applied methyl bromide had escaped to the atmosphere by 14 days after fumigation. 相似文献
2.
Desaeger JA Eger JE Csinos AS Gilreath JP Olson SM Webster TM 《Pest management science》2004,60(12):1220-1230
Movement and biological activity of 1,3-dichloropropene (1,3-D) and chloropicrin applied through drip irrigation in raised beds was investigated at three locations in the southeastern USA. Tests were conducted in fields with dense populations of nutsedge (Cyperus spp), with one location also having a high level of soil nematodes, both of which served as biological indicators of the distribution of effective concentrations of 1,3-D and chloropicrin. Objectives were (1) to gain a better understanding of 1,3-D and chloropicrin movement and the extent of biological activity outside of the wetted bed area, and (2) to examine the effect of application rate, application concentration and subsequent irrigation events on movement and activity of 1,3-D and chloropicrin. InLine, an emulsifiable concentrate containing 60.8% w/w 1,3-D and 33.3% w/w chloropicrin, was injected into polyethylene mulched beds through the drip tubes and water movement in the beds was visualized by adding a blue dye to the injection system. Gas concentrations of 1,3-D and chloropicrin in soil were measured using Gastec detection tubes at different positions relative to the drip tube at 1-4 days after InLine application. After one week, mulch was removed and nutsedge survival evaluated at different positions in the bed. High concentrations of 1,3-D and chloropicrin were measured at the bed center and midway between the bed center and the shoulder, but concentrations were low at the bed shoulder. Width of nutsedge control was significantly greater than width of water movement. Plant-parasitic nematodes were controlled over the entire bed width, but nutsedge re-emerged at the bed shoulders regardless of treatment. Higher application rates and concentrations of 1,3-D + chloropicrin resulted in higher fumigant concentrations in soil air. Irrigations subsequent to application reduced soil air concentrations of 1,3-D and chloropicrin and increased water movement, as did the use of two drip tubes instead of one. The data show that the pesticidal activity of 1,3-D + chloropicrin extends beyond the waterfront and indicate a significant degree of fumigant activity of emulsifiable 1,3-D + chloropicrin. However, unlike plant-parasitic nematodes, nutsedge could not be controlled over the entire bed width, regardless of rate, concentration and volume of water applied. 相似文献
3.
Wenming Zhang Milton E. McGiffen J. Ole Becker Howard D. Ohr James J. Sims Steven D. Campbell 《Pest management science》1998,53(1):71-79
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 相似文献
4.
Metam sodium (metam) is a widely used soil fumigant. Combined application of metam and other available fumigants is intended to produce synergic pesticidal effects for a broad spectrum of pest control in soil fumigation. This study aimed to test the compatibility of metam with the halogenated fumigants 1,3-dichloropropene (1,3-D), chloropicrin, methyl bromide, methyl iodide and propargyl bromide. Halogenated fumigants and metam were spiked simultaneously into organic solvents, water and moist soils, and metam-induced degradation of these halogenated chemicals was evaluated. In all three media, the halogenated fumigants were incompatible with metam and degraded via rapid chemical reactions. The degradation rate varied with halogenated fumigant species and increased as the amount of metam present was increased. In moist soil, 15-95% of the halogenated fumigants were decomposed within 72 h by metam at a 1:1 molar ratio. Combined application of Telone C-35 (62.5% 1,3-D + 35% chloropicrin) at 265 mg kg(-1) and Vapam (42% metam) at 567 mg kg(-1) in soil resulted in complete disappearance of the applied chloropicrin and 20-38% of the 1,3-D within 8 h. The results suggest that simultaneous application of halogenated fumigants and metam at the same soil depth will not maximize pest control. In practice, sequential treatment of soil or application at different soil depths is recommended when these two types of fumigants are used in combination. 相似文献
5.
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. 相似文献
6.
Catherine R Simpson Shad D Nelson Jerry E Stratmann Husein A Ajwa 《Pest management science》2010,66(6):686-692
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 相似文献
7.
Jrn Ole Becker Howard D. Ohr Nigel M. Grech Milton E. McGiffen James J. Sims 《Pest management science》1998,52(1):58-62
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. 相似文献
8.
BACKGROUND: Producers of perennial crop nursery stock in California use preplant soil fumigation to meet state phytosanitary requirements. Although methyl bromide (MB) has been phased out in many agricultural industries, it is still the preferred treatment in the perennial nursery industry and is used under Critical Use Exemptions and Quarantine/Preshipment provisions of the Montreal Protocol. The present research was conducted to evaluate reduced‐rate MB applications sealed with conventional and low‐permeability plastic films compared with the primary alternative material. RESULTS: Reduced rates (100–260 kg ha?1) of MB applied in combination with chloropicrin (Pic) and sealed with a low‐permeability plastic film provided weed and nematode control similar to the industry standard rate of 392 kg ha?1 MB:Pic (98:2) sealed with high‐density polyethylene (HDPE) film. However, the primary alternative chemical, 1,3‐dichloropropene (1,3‐D), tended to provide slightly lower pest control even on sites with relatively low plant parasitic nematode, soil‐borne pathogen and weed pest pressure. CONCLUSION: If California regulations change to allow the use of low‐permeability films in broadcast fumigant applications, the results of this research suggest that reduced rates of MB in perennial crop nurseries could serve as a bridge strategy until more technically, economically and environmentally acceptable alternatives are developed. Published 2010 by John Wiley & Sons, Ltd. 相似文献
9.
1,3‐Dichloropropene (1,3‐D), which consists of two isomers, (Z)‐ and (E)‐1,3‐D, is considered to be a viable alternative to methyl bromide, but atmospheric emission of 1,3‐D is often associated with deterioration of air quality. To minimize environmental impacts of 1,3‐D, emission control strategies are in need of investigation. One approach to reduce 1,3‐D emissions is to accelerate its degradation by incorporating organic amendments into the soil surface. In this study, we investigated the ability of four organic amendments to enhance the rate of degradation of (Z)‐ and (E)‐1,3‐D in a sandy loam soil. Degradation of (Z)‐ and (E)‐1,3‐D was well described by first‐order kinetics, and rates of degradation for the two isomers were similar. Composted steer manure (SM) was the most reactive of the organic amendments tested. The half‐life of both the (Z)‐ and (E)‐isomers in unamended soil at 20 °C was 6.3 days; those in 5% SM‐amended soil were 1.8 and 1.9 days, respectively. At 40 °C, the half‐life of both isomers in 5% SM‐amended soil was 0.5 day. Activation energy values for amended soil at 2, 5 and 10% SM were 56.5, 53.4 and 64.5 kJ mol?1, respectively. At 20 °C, the contribution of degradation from biological mechanisms was largest in soil amended with SM, but chemical mechanisms still accounted for more than 58% of the (Z)‐ and (E)‐1,3‐D degradation. The effect of temperature and amendment rate upon degradation should be considered when describing the fate and transport of 1,3‐D isomers in soil. Use of organic soil amendments appears to be a promising method to enhance fumigant degradation and reduce volatile emissions. Published in 2001 for SCI by John Wiley & Sons, Ltd 相似文献
10.
Reducing fumigant emissions after soil application 总被引：1，自引：0，他引：1
ABSTRACT Volatilization and soil transformation are major pathways by which pesticides dissipate from treated agricultural soil. Volatilization is a primary source of unwanted agricultural chemicals in the atmosphere and can significantly affect fumigant efficacy. Volatile pesticides may cause other unique problems; for example, the soil fumigant methyl bromide has been shown to damage stratospheric ozone and will soon be phased out. There is also great concern about the health consequences of inhalation of fumigants by people living in proximity to treated fields. Because replacement fumigants will likely face increased scrutiny in years ahead, there is a great need to understand the mechanisms that control their emission into the atmosphere so these losses can be minimized without loss of efficacy. Recent research has shown that combinations of vapor barriers and soil amendments can be effective in reducing emissions. In this paper, some potential approaches for reducing fumigant emissions to the atmosphere are described. 相似文献
11.
The phase-out of methyl bromide as a soil fumigant has stimulated research into the use of other soil fumigants for weed control. Methyl bromide, methyl iodide, propargyl bromide, 1,3-dichloropropene (1,3-D) and metam-sodium were tested alone and in combination with chloropicrin in laboratory experiments to determine their efficacy against Cyperus esculentus L (yellow nutsedge) tubers. Propargyl bromide and metam-sodium were the most efficacious fumigants tested, with EC50 values of 3.7 and 6.5 microM, respectively. The relative potencies of methyl iodide and chloropicrin were not significantly different but were 2.6 and 2.9 times more potent than methyl bromide, respectively. The EC50 values for all fumigants other than 1,3-D were significantly lower than that of methyl bromide. Combining each fumigant with 17% chloropicrin resulted in a synergistic interaction. The greatest increase in potency between the expected result and the actual result was a relative potency of 3.8 with the methyl bromide/chloropicrin combination. The smallest increase in efficacy was with propargyl bromide and chloropicrin, with a relative potency of 1.5. There was no significant difference between the EC50 values of methyl bromide/chloropicrin and methyl iodide/chloropicrin combinations. Combining 1,3-D with 17% chloropicrin resulted in an EC50 value for C. esculentus control similar to that of methyl iodide applied alone. 相似文献
12.
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。 相似文献
13.
A new method is described for tracing water movement in polyethylene film covered soil beds. Dye was delivered via a drip tape micro-irrigation system which was placed in the bed as the soil beds were shaped and covered with polyethylene film. The dye was injected into the system and irrigated with water for 4-24 h at 0.41-1.38 bar (41-138 kPa) pressure depending on the experiment. The dye appeared as blue circles on the soil surface within 20 min of injection and produced a three-dimensional pattern in the soil profile. Injection-irrigation-pressure scenarios were evaluated by measuring dye movement directly below and between emitters by sliding fabricated blades vertically into the bed at the desired examination point and excavating the soil away from the blade. The dye typically produced a U shape on the face of the bed and the area was calculated for each of these exposed faces. The area increased as the length of irrigation and water pressure increased. Interrupted irrigation (pulsing) scenarios did not alter the calculated areas encompassed by the dye compared to uninterrupted irrigation scenarios. The blue dye provided a direct, inexpensive and easy method of visualizing water movement in soil beds. This information will be used to optimize application of emulsifiable plant-care products in polyethylene film mulch beds. 相似文献
14.
Duniway JM 《Phytopathology》2002,92(12):1337-1343
ABSTRACT None of the chemical alternatives currently registered and available has the full spectrum of activity and versatility of methyl bromide as a pre-plant soil fumigant. Chloropicrin and 1,3-dichloropropene (Telone) can provide significant control of many plant pathogens in soil and growth stimulation in annual crops. These compounds, however, provide limited control of weeds or other residual plant materials in soil of concern in nursery production systems, and some perennial replant diseases. Methyl isothiocyanate generators such as metam sodium have broad biocidal activity in soil, but are more difficult to apply effectively. In most soil applications, the available alternatives are likely to be used in combinations, either as mixtures (e.g., 1,3-dichloropropene and chloropicrin) or sequentially (e.g., chloropicrin followed by metam sodium). They may also be supplemented with other more specific pesticides and cultural controls. Among the alternatives currently under active development but not yet available, methyl iodide and propargyl bromide probably have activity that most closely parallels that of methyl bromide in soil. However, all of the chemical alternatives to methyl bromide will be subject to continuing review and more regulation. Furthermore, we do not know the actual prospects for registration of the new fumigants currently under development and there is a risk that registered fumigants will not be available for large-scale use in soil indefinitely. 相似文献
15.
Physical, chemical and environmental properties of selected chemical alternatives for the pre-plant use of methyl bromide as soil fumigant 总被引：1，自引：0，他引：1
Ruzo LO 《Pest management science》2006,62(2):99-113
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. 相似文献
16.
Adaptation of soil solarization to the integrated management of soilborne pests of tomato under humid conditions 总被引：1，自引：0，他引：1
ABSTRACT Soil solarization was shown to be cost effective, compatible with other pest management tactics, readily integrated into standard production systems, and a valid alternative to preplant fumigation with methyl bromide under the tested conditions. Solarization using clear, photoselective, or gas-impermeable plastic was evaluated in combination with metham sodium, 1,3-dichloropropene + chloropicrin, methyl bromide + chloropicrin, pebulate, or cabbage residue. Strip solarization, applied to 20-cm-high, 0.9-m-wide beds, was conducted to achieve compatibility with standard production practices and resulted in soil temperatures 2 to 4 degrees C above those temperatures resulting when using conventional flatbed solarization. Soil temperatures were 1 to 2 degrees C higher at the edges of the raised beds, eliminating any border effects associated with solarization. Following a 40- to 55-day solarization period, the plastic was painted white and used as a production mulch for a subsequent tomato crop. The incidence of Southern blight and the density of Paratrichodorus minor and Criconemella spp. were lower (P < 0.05) in solarized plots. No differences (P < 0.05) in the incidence of Fusarium wilt and the density of nutsedge and Helicotylenchus spp. were observed between plots receiving solarization and plots fumigated with a mixture of methyl bromide + chloropicrin. The severity of root galling was lower (P < 0.05) when soil solarization was combined with 1,3-dichloropropene + chloropicrin (16.2 + 3.4 g/m(2)) and a gas-impermeable film. The incidence of bacterial wilt was not affected by soil treatments. Marketable yields in plots using various combinations of soil solarization and other tactics were similar (P < 0.05) to yields obtained in plots fumigated with methyl bromide + chloropicrin. The results were validated in several large scale field experiments conducted by commercial growers. 相似文献
17.
The application of a granular formulation of sodium azide (Smite 8G), to pine nursery beds at rates of 0, 22.4, 67.2 and 134.5 kg active ingredient ha?1 under water seal or plastic seal, was compared over a 1-year period with methyl bromide, applied at a rate of 650 kg ha?1, to determine the effects of soil bacterial populations, soil enzymic activities, development of mycorrhizal roots, weed population and incidence of root diseases. Bacterial populations at 24 days after treatment had increased in proportion to the amount of sodium azide added; however, highest numbers of bacteria were recorded from the methyl bromide-treated plot. At the last sampling date no significant differences were observed in bacterial populations among treatments. Neither sodium azide nor methyl bromide caused permanent changes in soil enzymic activities or adversely affected mycorrhizal root development on pine seedlings. Sodium azide at 134.5 kg ha?1 and methyl bromide both significantly decreased the number of Cyperus spp. plants in plots; however, the number of pine seedlings exhibiting a root disease was highest in plots receiving these treatments. 相似文献
18.
黄土高原旱地不同保护性耕作措施对马铃薯田土壤水温效应及产量的影响 总被引：6，自引：0，他引：6
设计实施了黄土高原西部旱农区马铃薯传统耕作(T)和五种保护性耕作措施:垄上覆膜沟内覆草摆种(PDSS)、垄上覆膜沟内覆草浅播(PDSSH)、垄上覆草摆种(RSS)、平作覆草摆种(FSS)和垄上不覆膜沟内覆草摆种(DSS)的大田对比试验,对不同耕作措施下各层次土壤水分、地温及产量进行了研究.结果表明:马铃薯免耕秸秆覆盖能明显改善0～80 cm土壤贮水量,特别是对0～30 cm土壤贮水量的影响尤为突出;与传统耕种相比,免耕秸秆覆盖可以降低各个土壤测定层的日均积温(≥0℃),并能在晴天14∶00时有效降低结薯层的温度,结薯层的温度FSS为27～29℃,PDSSH为21～28.5℃,较传统耕种的27～32℃略低,降低了高温对马铃薯生长的不利影响;免耕秸秆覆盖除RSS外,出苗率和产量均高于传统耕种,且FSS的产量最高,达27 468.3 kg/hm2,较传统耕种增产30.05%. 相似文献
19.
Evaluation of chemical and integrated strategies as alternatives to methyl bromide for the control of root-knot nematodes in Greece 总被引：3，自引：0，他引：3
Current environmental awareness has led to a greater demand for alternative nematode control strategies. Three field experiments were established to compare management tactics on cucumber in commercial greenhouses naturally infested with root-knot nematodes (Meloidogyne spp). Cucumber rootstocks which have shown resistance to soil-borne diseases were tested to reveal any resistance/tolerance to root-knot nematodes, and integration of these rootstocks with nematicides was investigated. Metham-sodium and 1,3-dichloropropene (1,3-D) provided good control of nematode populations when their application was followed by the application of a non-fumigant nematicide such as cadusafos or oxamyl. Neither fumigant could provide season-long control of nematode populations, and a further application of cadusafos was required for satisfactory control. The efficacy of metham-sodium was significantly increased when injected into soil in comparison with its application through the drip irrigation system. The use of rootstocks resistant to soil-borne fungal pathogens used together with chemical means of nematode control provided promising results for their further use in integrated strategies as alternatives to methyl bromide. However, the latter was the superior treatment for the control of root-knot nematodes in soil infested with residues of galled roots. Dazomet, metham-sodium nor the non-fumigant nematicides oxamyl and fenamiphos could reduce nematode population as efficiently as methyl bromide. None of the chemicals tested except methyl bromide could enter galled roots and kill surviving nematodes. 相似文献
