蔬菜大棚常用土壤消毒剂

对蔬菜大棚常用的几种土壤消毒药荆的性能、使用方法、应用领域、消毒机理及各自的特点进行了阐述.介绍了几种可以取代溴甲烷的土壤消毒剂,指出了今后用于蔬菜大棚的土壤消毒剂的发展趋势.今后土壤消毒荆的开发应朝着安全、高效、环境友好、使用方便的方向发展,以适应不同农业种植的各种要求.     

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.     

The effect of pretreatments of carbon-coated formvar films on the trapping of potato leafroll virus particles using immunosorbent electron microscopy

The application of electrical charges on carbon-coated formvar films had a marked effect on the trapping of virus particles by immunosorbent electron microscopical techniques. On grids, positively charged with ethidium bromide, numbers of virus particles were high, and almost equal to those trapped with the aid of protein A in combination with a negative charge.Samenvatting Het aanbrengen van elektrische lading op koolstof-formvar vliezen beïnloedde de adsorptie van virusdeeltjes aan het vlies, bedekt met homoloog antiserum (-globulinen). Op vliezen met een positieve lading werd een veel groter aantal virusdeeltjes waargenomen dan op de neutrale of negatief geladen vliezen. Positief geladen vliezen werden verkregen door behandeling met ethidium-bromide. Negatief geladen vliezen werden verkregen door behandeling met geïoniseerd argongas. Op de negatief geladen vliezen bleken grote hoeveelheden verontreinigingen van allerlei aard te precipiteren. Bovendien was het beeld van de virusdeeltjes vaag. Negatief geladen vliezen gaven wel goede resultaten ten aanzien van het vangen van virusdeeltjes in combinatie met proteine A en -globulinen.     

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％。     

Notes: Effects of compost application on the dynamics of soil nitrogen and manganese after steam sterilization

(Jpn. J. Soil Sci.Plant Nutr., 77, 307–311, 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.     

Modelling the kinetics of ethyl formate sorption by wheat using batch experiments

BACKGROUND: Ethyl formate formulations are being considered to replace methyl bromide for fast grain disinfestation. Grain adsorbs ethyl formate rapidly, which can result in inadequate fumigation concentrations and unacceptable grain residues. A model of ethyl formate sorption kinetics will enable fumigation approaches to be determined that meet disinfestation and food safety requirements. RESULTS: This paper identifies all mass transport processes involved in ethyl formate sorption by wheat from published and experimental evidence. The model accounts for reaction losses of ethyl formate in air and grain using first‐order kinetics, transport in the gas and solid phases with linear mass transfer coefficients and uses a linear partition relationship representation of sorption equilibrium. Batch experimental data were measured to determine model coefficients. Novel gaseous breakdown data for ethyl formate in air were measured, and first‐order kinetics was demonstrated, although the specific reactions involved were not identified. CONCLUSION: The model predicts air and grain fumigant concentrations relevant for grain disinfestation and food residue contamination successfully. The form of the model should be applicable to all fumigant–grain systems, as it accounts for the diffusion and reaction influences known to occur with all modern fumigants under concentration and exposure conditions relevant to industry. Copyright © 2009 CSIRO, Australia. Published by John Wiley & Sons, Ltd.     

Effect of nitrogen application on the bromide content of lettuce grown under glass

Abstract

Lettuce (Lactuca sativa L.) collected from eleven trials with different rates of application of ammonium nitrate limestone was analysed for bromide. Nitrogen application (0–2.6 kg N/100 m²) decreased the bromide content of the lettuce in most trials. This decrease varied from 0 to 50%, with 27% as the average. A correlation was found between the bromide content of the crop and that of the soil extract at the conclusion of the trials. The correlation could be improved by calculating a multiple regression equation which included the nitrate content of the soil extract.     

Juvenile idiopathic epilepsy in Egyptian Arabian foals: 22 cases (1985-2005)

Background:Epilepsy is relatively uncommon in horses compared with other species and limited information is available.
Hypothesis:The objectives of the study were to describe the age of onset, clinical signs, clinicopathologic data, electroencephalographic findings, treatment, and outcome, including long-term prognosis in Arabian foals with idiopathic epilepsy.
Animals:Twenty-two foals were included in the study.
Materials and Methods: Medical records from 1985 to 2005 were reviewed.
Results:The age of onset of affected foals ranged from 2 days to 6 months. Seizures were characterized by generalized tonic and clonic motor activity, staring, and loss of consciousness. The most common postictal signs were transient blindness and abnormal mental status. The interictal neurologic examination was otherwise normal. Clinicopathologic data and imaging diagnostics were normal except in 4 foals that developed complications. Electroencephalography revealed epileptiform activity in 9 of 13 foals. Foals were treated with benzodiazepines for the short-term; whereas phenobarbital was used over the long-term. Potassium bromide was added in 3 foals in which seizures were multiple, frequent, and difficult to control. The long-term prognosis was favorable with cessation of seizures by 1 year of age. The most common complication was head trauma. The most common concurrent disease was pneumonia.
Conclusions and Clinical Importance: Juvenile idiopathic epilepsy of Egyptian Arabian foals has an early clinical onset but appears to be self-limiting. Information obtained from this study strongly suggests a heritable condition that merits further investigation.