高大平房仓的局部改造对气密性改善的探索

针对高大平房仓气密性较差的情况，对其进行局部改造，提高仓房的气密性，以适应低剂量的环流熏蒸杀虫。     

A simulation model for fate and transport of methyl bromide during fumigation in plastic‐mulched vegetable soil beds

A coupled water‐heat and chemical transport model was used to describe the fate and transport of methyl bromide fumigant in low‐density polyethylene plastic‐mulched soil beds used for vegetable production. Methyl bromide transport was described by convective‐dispersive processes including transformations through hydrolysis. Effects of non‐isothermal conditions on chemical transport were considered through inclusion of temperature effects on transport parameters. An energy‐balance approach was used to describe the plastic‐mulched boundary condition that controls the thermal regime within the soil bed. Simulations were made for variable water‐saturation regimes within the bed and for different depths of fumigant injection. Simulations for various scenarios revealed that large amounts (20–44% over a 7‐day period) of applied methyl bromide are lost from the un‐mulched furrows between the beds. Plastic mulching of the bed was found to be only partially effective (11–29% emission losses over a 7‐day period) in reducing atmospheric emissions. Deep injection of fumigant and saturating the soil with water both led to increased retention of methyl bromide within the soil and less emission to the atmosphere. However, deep injection was unfavorable for effective sterilization of the crop root zone. © 2000 Society of Chemical Industry     

磷化氢与二氧化碳混合熏蒸储藏面粉杀螨抑菌试验报告

用剂量1.5～2g／m     

Efficacy of reduced rate fumigant alternatives and methyl bromide against soilborne pathogens and weeds in western forest nurseries

Preplant soil fumigation is commonly used to control soilborne pathogens and weeds in forest seedling nurseries of Oregon and Washington. However, lower chemical inputs are desired to meet state and federal application regulations, to minimize buffer zone size requirements, and to help protect the environment. Therefore, the objectives of this research were to evaluate the efficacy of three reduced rate soil fumigants under totally impermeable film (TIF) in managing soilborne diseases and weeds, and to determine if combined applications of up to four biocontrol agents improved soilborne disease control. Reduced rates of methyl bromide, metam sodium, and 1,3-dichloropropene, all applied in combination with chloropicrin, were effective in decreasing soil populations of Pythium and Fusarium as well as the presence of Pythium in root debris from the previous crop. The roots of Douglas-fir (Pseudotsuga menziesii) seedlings transplanted into each fumigant treatment were also colonized less by Pythium and Fusarium than those transplanted into nonfumigated control plots. However, biocontrol treatments were not effective against either pathogen. Weed biomass and weeding times were also significantly reduced by fumigation. Application costs were similar for all three fumigant treatments, but seedling size was largest from the methyl bromide and metam sodium treatments followed by the 1,3-dichloropropene treatment. Based on the results of this study, reduced rates of methyl bromide, metam sodium, and 1,3-dichloropropene show promise in managing soilborne diseases and weeds in forest nurseries.     

Detection and characterisation of strong resistance to phosphine in Brazilian Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae)

As failure to control Rhyzopertha dominica (F.) with phosphine is a common problem in the grain-growing regions of Brazil, a study was undertaken to investigate the frequency, distribution and strength of phosphine resistance in R. dominica in Brazil. Nineteen samples of R. dominica were collected between 1991 and 2003 from central storages where phosphine fumigation had failed to control this species. Insects were cultured without selection until testing in 2005. Each sample was tested for resistance to phosphine on the basis of the response of adults to discriminating concentrations of phosphine (20 and 48 h exposures) and full dose-response assays (48 h exposure). Responses of the Brazilian R. dominica samples were compared with reference susceptible, weak-resistance and strong-resistance strains from Australia in parallel assays. All Brazilian population samples showed resistance to phosphine: five were diagnosed with weak resistance and 14 with strong resistance. Five samples showed levels of resistance similar to the reference strong-resistance strain. A representative highly resistant sample was characterised by exposing mixed-age cultures to a range of constant concentrations of phosphine for various exposure periods. Time to population extinction (TPE) and time to 99.9% suppression of population (LT(99.9)) values of this sample were generally similar to those of the reference strong-resistance strain. For example, at 0.1, 0.5 and 1.0 mg L(-1), LT(99.9) values for BR33 and the reference strong-resistance strain were respectively 21, 6.4 and 3.7 days and 17, 6.2 and 3.8 days. With both strains, doubling phosphine concentrations to 2 mg L(-1) resulted in increased LT(99.9) and TPE. High level and frequency of resistance in all population samples, some of which had been cultured without selection for up to 12 years, suggest little or no fitness deficit associated with phosphine resistance. The present research indicates that widespread phosphine resistance may be developing in Brazil. Fumigation practices should be monitored and resistance management plans implemented to alleviate further resistance development.     

南方地区高大平房仓环流熏蒸应用试验

根据我国南方高温高湿地区气候特点,选择最佳的有效杀虫时机,适当控制用药量,并做好仓房的隔热保温措施,高大平房仓可以实现一年一次环流熏蒸彻底杀死储粮害虫,以达到降低用药量,减少熏蒸杀虫次数的目的.     

磷化铝自然潮解环流熏蒸生产性试验报告

用CTHC125×65型磷化氢环流熏蒸仓外投药器投药进行环流熏蒸试验,结果表明,磷化铝自然潮解环流熏蒸是解决深粮层熏蒸杀虫的一种使用安全、操作简便、经济实用的方法。采用该装置仓内磷化氢气体分布均匀,杀虫效果良好。     

Fumigant distribution in forest nursery soils under water seal and plastic film after application of dazomet, metam-sodium and chloropicrin

Adequate concentration, exposure time and distribution uniformity of activated fumigant gases are prerequisites for successful soil fumigation. Field experiments were conducted to evaluate gas phase distributions of methyl isothiocyanate (MITC) and chloropicrin (CP) in two forest-tree nurseries. Concentrations of MITC and CP in soil air were measured from replicated microplots that received dazomet, metam-sodium and CP. Half of the plots were covered with high-density polyethylene tarp immediately after fumigation; the other half were not covered but received daily sprinkler irrigation for 1 week to create and maintain a water seal. The magnitude of MITC concentrations was similar between nurseries for metam-sodium in both tarp and water seal treatments and for dazomet in the tarp treatment. Consistently greater MITC and CP concentrations were found in the upper 30 cm of soil in the tarped plots compared with the water-sealed plots. Despite potential environmental and economic benefits with the water seal method, tarp covers were more reliable for achieving and maintaining higher MITC and CP concentrations and less prone to variations due to irrigation/rain, soil bulk density and other environmental conditions.     

溴甲烷土壤熏蒸技术在秋季温室番茄应用的研究初报

在夏秋高温季节,采用溴甲烷土壤熏蒸技术,可有效地防治温室番茄的土传病害和增加番茄产量,用药剂量为２５ｇ／ｍ２、５０ｇ／ｍ２、７５ｇ／ｍ２的条件下,其对番茄枯萎病的防治效果可达６８．７７％、８７．４９％、９３．７４％,对根结线虫病的防效可达８２．８５％、９２．５２％、９７．１５％,番茄增产幅度可达１４．４％、２３．９％、２９．２％。