溴甲烷土壤处理防治烟草病虫草害效果初报

溴甲烷是一种高效熏蒸剂,多年来被用作仓贮虫害的防治,在国外早已被用于烟草苗床土壤处理防治烟草病、虫、草害。我们今年承担了农业科学院烟草所郑州点的农药试验任务,将溴甲烷用于处理烟草苗床土壤,取得了明显防效,现将其结果简报如下:     

烟草苗床化学除草试验研究

经过１９９７～１９９８年连续２年的试验研究表明：烟草苗床化学除草以溴甲烷、大惠利防除效果最好，防效达９０％～１００％。高效盖草能、威霸、精稳杀得对苗床单子叶杂草防效较好，达７８％以上，但对双子叶杂草防效较差。都尔、禾耐斯处理苗床引起严重药害，烟苗出苗推迟，出苗率低，而且严重畸形。综合分析防草效果、烟苗长势和经济投入，以大惠利最适宜于在我国广大烟区苗床推广应用。     

溴甲烷熏蒸烟草苗床(或土壤)灭虫、防病、除草

溴甲烷为一种卤代物类熏蒸杀虫剂,是应用于防治仓储害虫较早的熏蒸剂。由于该药剂杀虫谱广,扩散性好,药效显著,已广泛用于仓库、厂房、车船等处的熏蒸,灭虫、灭菌、灭鼠。用溴甲烷熏蒸烟草苗床或育苗土壤,防治烟草苗期的病、虫、草害,作为烟草生产上培育无病壮苗的一项技术措施,这在世界主要的产烟国家已广泛应用。我国在这方面的开发应用起步较晚。1987年我们与连云港海水化工厂、美国大湖化学公     

我国烟草苗床甲基溴替代研究现状及展望

溴甲烷是一种高效、广谱的土壤熏蒸剂,在我国烟草苗床上广泛使用,由于显著消耗臭氧层,需要寻找有效替代技术。本文综述了国内外甲基溴替代技术研究现状,对我国烟草苗床替代技术进行了分析,并对我国育苗过程中存在的问题作了探讨,提出通过育苗技术和苗床害物IPM策略结合,可望有效替代甲基溴,实现良好的社会、生态和经济效益。      

溴甲烷熏蒸烟草苗床(或土壤)灭虫、防病、除草使用说明

用溴甲烷熏蒸烟草苗床或育苗土壤,防治烟草苗期的病、虫、草害,作为烟草生产上培育无病壮苗的一项技术措施,这在世界主要的产烟国家已广泛应用。一、溴甲烷熏蒸烟草苗床(或土壤)的方法溴甲烷是一种有毒的液化气体,由于气体有强大的扩散力,它可以在薄膜覆盖的苗床(或土堆)里向各方位无孔不入地扩散渗透,从而达到灭虫、灭菌防病、除草的目的。     

斯美地防除烤烟苗床杂草试验报告

经随机区组４ 次重复田间试验,证明３２ ．７ ％ 斯美地（ 土壤熏蒸剂） 对烤烟苗床常见杂草具有显著的除草效果：斯美地２５ｍｌ／ｍ ２ 除草效果达７１ ．９ ％ ,５０ｍｌ／ｍ２ 除草效果达８７ ％ ,７５ ｍｌ／ｍ２ 除草效果达８８ ．１ ％ ,１００ｍｌ／ｍ ２ 除草效果达８９ ．６ ％ 。该药剂对烟种萌发和烟苗安全,对施药人员安全,可替代苗床手工除草。用药量以５０ ～７０ｍｌ／ｍ ２ 为宜。     

满秋在蔗地除草试验报告

本文对43%满秋悬浮剂对蔗田杂草的防除效果进行了试验与分析。3个试验点的结果表明,该药剂对甘蔗安全,对蔗田阔叶杂草与莎草科杂草的防除效果较好,对禾本科杂草的防除效果一般,能显著提高甘蔗产量与含糖量,可在各蔗区扩大试验示范,因地制宜推广。     

不同除草剂对烟草大田杂草防除研究初报

采用除草剂敌草胺、F6285、除芽通对烟草大田杂草防除进行了研究.结果表明,供试的3种除草剂均具有较好的控草效果.其中敌草胺在施药后30d、60d对杂草的防效为72.0%、57.4%,且对烟株生长抑制作用较小.F6285施药后30d、60d对杂草防效均为100%,但对后茬物有一定影响.除芽通虽对杂草具有较好的防效,但对烟株生长抑制作用较强.     

几种药剂对烟草甲生物活性的测定

为了开发有效的贮烟防护剂,试验了7种药剂对烟草甲幼虫和4种药剂对烟草甲成虫的触杀毒力。结果表明,7种药剂中97.1%氟氯氰菊酯对烟草甲幼虫的致死中量最低,对烟草甲幼虫的触杀毒力最强,其次是98.5%溴氰菊酯,27%高效氯氰菊酯,90%甲基嘧啶磷,65.9%氰戊菊酯;供试药剂中对烟草甲幼虫触杀毒力最弱的是66.67%的甲氨基阿维菌素苯甲酸盐。而对烟草甲成虫触杀毒力最强的是90%甲基嘧啶磷。     

新型烤烟苗床土壤消毒剂药效试验

用4种土壤熏蒸消毒剂斯美地、适每地、必速灭和棉隆对烤烟苗床进行了消毒除草试验.播种40d后调查结果为4种农药对单子叶杂草防效分别是97.56%、96.71%、88.53%、95.77%,对双子叶杂草防效分别是99.45%、99.71%、99.69%、99.32%,经方差分析证明,4种农药之间差异不显著,与清水处理相比,4种农药差异达极显著水平.     

The toxic action of phosphine in combination with some alkyl halide fumigants and carbon dioxide against the eggs of Tribolium castaneum Herbst (Coleoptera: Tenebrionidae)

The toxicity of phosphine, three alkyl halide fumigants (ethylene dibromide, methyl bromide and methyl iodide), carbon dioxide, mixtures of phosphine + alkyl halide fumigants, and phosphine + carbon dioxide, to 1-, 2-, and 3-day-old eggs of Tribolium castaneum Herbst was studied. Combinations of phosphine and alkyl halide fumigants showed antagonism as evidenced by their joint action ratios at the LD₉₀ (< 1). The mortality data indicated that mixtures of phosphine and carbon dioxide were more effective than either alone. At LD₅₀, the order of toxicity of the individual fumigants for a 24 hr exposure and on a weight basis (mg fumigant/litre of air) was: phosphine > methyl iodide > ethylene dibromide > methyl bromide. A decline in susceptibility of eggs with age for methyl bromide and ethylene dibromide and a peak tolerance at 2 days for carbon dioxide were noted.     

Movement of halogenated fumigants through wheat

The movement of fumigants was studied by gas chromatography on columns of wheat coupled directly to a detector. The fumigants were methyl bromide, methylene dichloride, carbon tetrachloride, chloropicrin and ethylene dibromide. Their chromatographic behaviour was the same with carbon dioxide as carrier gas as with air or nitrogen. Improved distribution of fumigants added with carbon dioxide in silos is attributed to other factors and not to changes in the dynamics of adsorption of fumigant to wheat.     

Effect of surface tarp on emissions and distribution of drip-applied fumigants

Soil fumigants are used to control a wide variety of soil-borne pests in high-cash-value crops. Application of soil fumigants through drip irrigation systems is receiving increasing attention as a method to improve the uniformity of fumigant application. Little information is available on the emissions and soil distribution of fumigants following subsurface drip application, or the effect of plastic tarp on fumigant emissions in these systems. In these experiments, the fumigant compounds 1,3-dichloropropene (1,3-D), Vapam (a methyl isothiocyanate (MITC) precursor), and propargyl bromide (PrBr) were applied to soil beds via drip irrigation at 15 cm depth. Beds were tarped with either standard 1-mil high-density polyethylene (HDPE) or a virtually impermeable film (VIF), leaving the furrows bare. Cumulative emissions of 1,3-D, MITC, and PrBr in these tarped bedded systems was very low, amounting to <10% of the applied mass. These experiments were conducted in the winter months, with average air temperatures of 12-15 degrees C. Cumulative emissions of MITC and 1,3-D from a sandy loam field soil were decreased by > or =80% by tarping the bed with VIF rather than HDPE. A large fraction of the 1,3-D and PrBr flux was from the untarped furrows in VIF-tarped plots, indicating that inhibiting volatilization from the furrow will be important in further reducing emissions in these systems. Monitoring the fumigant distribution in soil indicated that tarping the bed with VIF resulted in a more effective containment of fumigant vapors compared to use of a HDPE tarp.     

Effect of environmental conditions on the permeability of high density polyethylene film to fumigant vapors

Soil fumigation in greenhouses or agricultural fields often includes tarping the soil surface with polyethylene (PE) films to contain the fumigant in the soil and reduce emissions to the atmosphere. Previous research has demonstrated that PE films are permeable to methyl bromide and other fumigant compounds. In these experiments, the effect of temperature, fumigant mixtures, condensed water, and field aging on the permeability of high-density polyethylene (HDPE) was determined. Mass transfer coefficients (h, a measure of permeability) of the fumigants methyl bromide, 1,3-dichloropropene, propargyl bromide, and chloropicrin across HDPE films were determined. In these studies, temperature and HDPE film type had the largest impact on the h of fumigant compounds across HDPE films. Other factors investigated, including fumigant mixtures, condensed water on the film, and field aging of UV-stabilized film, did not have a significant impact on h. The results of these experiments suggest that the permeability of an intact piece of an agricultural film will increase with increasing temperature but is relatively constant despite changes in other environmental conditions.     

Effect of application variables on emissions and distribution of fumigants applied via subsurface drip irrigation

Soil fumigation is useful for controlling soil-borne pests and diseases in high-cash-value crops. Fumigants are highly volatile, and approaches to reduce atmospheric emissions are required to protect human and environmental health. Application of fumigants through drip irrigation has been proposed as a means to decrease fumigant emissions, improve fumigant distribution in soil, and minimize worker exposure. These experiments were conducted to investigate the effect of the configuration of the drip system on the volatilization and distribution of the fumigants 1,3-dichloropropene (1,3-D), propargyl bromide (PrBr), and methyl isothiocyanate (MITC) in bedded systems. Results indicated that changing the drip emitter spacing and using multiple drip lines in each bed had little effect on the emissions and distribution of any fumigant. Increasing the depth of application from 15 to 30 cm reduced volatilization of MITC by approximately 20 to >90%; emissions were reduced due to a decrease in the flux from the bed top, and deeper injection did not change the amount of fumigant volatilized from the bed side slope and furrow. Increasing the application depth resulted in a slight decrease in the rate of fumigant dissipation in soil, indicating the potential for some improvement in pest-control efficacy with deeper application.     

Effects of two fumigants and a fungicide formulation on the development of kiln brown stain in radiata pine lumber

Two fumigants (methyl bromide and sulphuryl fluoride) were used to treat freshly sawn radiata pine (Pinus radiata D. Don) lumber and log sections to evaluate their influence on development of kiln brown stain. Both treatments reduced severity of stain when compared with controls. The sulphuryl fluoride treatment was notably better than methyl bromide at the highest fumigant dosage, but levels of overall stain were still considered unacceptable with only 20–30% of lumber having either no or slight stain beneath the surface. Sulphuryl fluoride showed superior penetration into sapwood compared to methyl bromide as determined by a colour assay of parenchyma cell viability. A fungicide formulation which was successful in preventing brown stain in kiln dried eastern white pine was ineffective against kiln brown stain in radiata pine. The results of the present study indicates that the mechanism for kiln brown stain in radiata pine differs from that in eastern white pine.     

Mitigating 1,3-dichloropropene, chloropicrin, and methyl iodide emissions from fumigated soil with reactive film

Implicated as a stratospheric ozone-depleting compound, methyl bromide (MeBr) is being phased out despite being considered to be the most effective soil fumigant. Its alternatives, i.e., 1,3-dichloropropene (1,3-D, which includes cis and trans isomers), chloropicrin (CP), and methyl iodide (MeI), have been widely used. High emissions of MeI from fumigated soil likely put farm workers and other bystanders at risk of adverse health effects. In this study, two types of constructed reactive film were tested for their ability to mitigate emissions of 1,3-D, CP, and MeI using laboratory permeability cells. Before activation, these films act as a physical barrier to trap fumigants leaving soil. After activation of the reactive layer containing ammonium thiosulfate solution, the films also act as a sink for the fumigants. Over 97% of trans-1,3-D and 99% of the cis-1,3-D, CP and MeI were depleted when they passed into the reactive film. Half-lives (t(1/2)) of cis-, trans-1,3-D, CP and MeI under activated reactive film were 1.2, 1.4, 1.6, and 2.0 h respectively at 40 °C.     

The toxicity of twelve fumigants to three species of mites infesting grain

Eggs of Tyrophagus longior, Acarus siro and Glycyphagus destructor were highly tolerant of each fumigant tested at 10°C while mobile stages were susceptible. Some eggs of T. longior survived the highest test dosages of methyl bromide, phosphine, ethylene oxide, ethyl formate, methallyl chloride and ethyl bromide. The ascending order of toxicity for the other fumigants, as judged by the ct product needed to kill all eggs, was methyl chloroform (MC), carbon tetrachloride (CTC), ethylene dichloride (EDC), methyl formate, ethylene dibromide and acrylonitrile. The toxicity of EDC was generally enhanced by the addition of MC or CTC, though dosages for control were still high, and a single fumigation can only be expected to provide a short-term absence of mobile stages. If complete control is required, this can be achieved by two treatments at a low dose if these are separated by an interval during which the surviving eggs hatch but do not reach the adult stage. The length of this interval depends on temperature and at 10°C is about 7 weeks, at 15°C 3 weeks and at 20°C 2 weeks.     

Predicted gas loss of sulfuryl fluoride and methyl bromide during structural fumigation

Elimination of insects in grain-milling facilities requires the periodic use of a gaseous insecticide (fumigant) that can destroy pests. Ideally, the fumigant concentration within a treated building should remain constant during the fumigation process to enhance efficacy while minimizing the amount of fumigant required. However, fumigant is often slowly lost through cracks and crevices within the structure. Wind impact on this leakage loss and in natural ventilation is explored using computational fluid dynamics (CFD). Two surrogate enclosure geometries, based on actual commercial grain mills, are used in the analysis. Building materials are assumed impermeable to fumigants, and cracks within structures are approximated as square regions where permeability parameters can be specified (i.e., porous jumps). Half-loss times (HLT) for sulfuryl fluoride (SF) and methyl bromide (MB) within the structure can be simulated. When diffusion dominates (no wind), SF had increased leakage rates of ∼5.4% over MB. However, simulated HLT due to diffusion are in the order of years for both fumigants. If the wind is blowing at measurable rates, convection-driven losses dominate and leakage from the mill is independent of the fumigant being used. Predicted half-loss times for MB and SF are statistically indistinguishable for external wind velocities from 0.125to 8 m s^-1. Therefore, HLTs are insensitive to fumigant physicochemical properties when the wind is blowing. Representative and diverse wind-frequency analysis for California and Texas show limited intervals of calm wind periods, and median wind speeds at or above those investigated in this analysis. Thus, decisions for product use should be based on efficacy, cost, and environmental impact, since convective-induced leakage rates are similar.