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1.
The degradation of DE-498 (proposed common name flumetsulam) was studied in 21 US soils as a first step in developing a management plan for this new herbicide. Degradation half-lives were shorter in soils that adsorbed the compound less. Adsorption was lower in soils with higher pH and lower organic carbon content. Degradation half-lives were thus influenced by both pH and organic carbon: they were in the range 2–4 weeks in higher pH soils (pH 5 7.0) unless the organic carbon content was above 2.5%, at which half-lives were in the range 1–3 months. In medium pH soils (6.4 pH 6.9) half-lives were 1–2 months, while in lower pH soils (5.9 pH 6.3) they were 1–4 months. The laboratory data were supported by the response of sunflowers (Helianthus annuus L.) planted 1 year after application of flumetsulam to different soils. A quantitative model relating half-life to sorption Kd (r2= 0.85) was coupled with an additional equation relating sorption Kd to the proportion of neutral and anionic forms of the compound at different pH values. The study allows estimates of this herbicide's degradation in soil to be made if its pH and organic carbon content are known. Degradation d'un herbicide sulfonamide en fonction de la capacité d'absorption du sol La dégradation du flumetsulam a étéétudiée dans les sols aux Etats Unis comme premier stade dans le développement d'un plan d'utilisation de ce nouvel herbicide. Les demi-vies de dégradation étaient plus courtes dans les sols qui absorbaient moins le produit. L'absorption était plus faible dans les sols à pH élevé et à faible teneur en carbone organique. Les demi-vies étaient ainsi sous l'influence du pH et du carbone organique: elles étaient de 2 à 4 semaines pour les pH de sols élevés (pH 7) sauf si le carbone organique était au dessus de 2,5%, dans ce cas, les demi-vies etaient de 1 à 3 mois. Dans les sols à pH moyen (6,4 pH 6,9) les demi-vies étaient de 1 à 2 mois, tandis que dans les sols à pH faible (5,9 pH 6,3) elles étaient de 1 à 4 mois. Les résultats de laboratoire ont été confirmés par le comportement de tournesols plantés un an aprfès l'application de flumetsulam dans différents sols. Un modèle reliant la demi-vie au coefficient d'absorption Kd (r2= 0.85) a été couplé avec une équation additionelle reliant le coefficient d'absorption Kd à la proportion de particules neutres et anioniques de la molécule aux différents pH. L'étude permet de faire des estimations de la dégradation de cet herbicide dans le sol dès que le pH et la teneur en carbone organique sont connus. Abbau eines Sulfonamid-Herbizids als Funktion der Bodensorption Der Abbau von Flumetsulam (DE-498) wurde in 21 Böden untersucht, um eine Grundlage zur Produktentwicklung dieses neuen Herbizids zu gewinnen. Die 50%ige Verlustrate (DT50) war in schwächer sorptiven Böden kürzer. Bei hohem pH-Wert und geringem Gehalt an organischer Substanz war die Adsorption schwächer. Die DT50 wurde durch den pH-Wert und den Gehalt organischer Substanz wie folgt beeinflußt: Sie betrug 2 bis 4 Wochen in Böden mit pH >7,0 (wenn der Corg-Gehalt nicht über 2,5% lag; dort dann 1 bis 3 Monate), 1 bis 2 Monate bei 6,4 < pH < 6,9 und 1 bis 4 Monate bei 5,9 < pH < 6,3). Die Ergebnisse der Laboruntersuchungen wurden durch Untersuchungen an Sonnenblumen gestützt. die 1 Jahr nach Applikation von Flumetsulam auf verschiedenen Böden angebaut wurden. Ein quantitatives Modell über das Verhältnis der Verlustrate zum Sorptionskoeffizienten Kd (r2= 0,85) wurde mit einer zusätzhchen Gleichung der Beziehung des Sorptionskoeffizienten Kd zum Verhältnis der neutralen und der anionischen Verbindungen des Wirkstoffs bei verschiedenen pH-Werten verknüpft. Aufgrund der Untersuchungen kann der Abbau dieses Herbizids in Böden bekannten pH-Werts und Corg-Gehalts abgeschätzt werden.  相似文献   

2.
A total of 146 samples of different kinds of cheeses produced in Spain were analysed in order to ascertain the specific contamination pattern. The organochlorine compounds studied were those most commonly investigated in previous surveys: α-HCH, β-HCH, γ-HCH (lindane), γ-HCH, chlordane, aldrin, dieldrin, endrin, heptachlor, heptachlor epoxide, and the isomers and metabolites of DDT. α-HCH, β-HCH, γ-HCH, chlordane, p,p′, DDT, and p,p′-DDE were found in more than 76% of samples; p,p′-DDE and γ-HCH were the most frequently detected, with frequencies of 100 and 97.9% respectively. γ-HCH, aldrin, dieldrin, heptachlor, heptachlor epoxide, o,p′-DDT, p,p′-DDD and o,p′-DDD were observed at lower frequencies. No residues of endrin were detected in any sample. Insecticides exceeding the maximum residue limits (MRLs) were chlordane, β-HCH, α-HCH and γ-HCH, with 42, 20, eight and six samples respectively. Mean residues of organochlorines found were as follows (μ kg?1 butterfat): α-HCH = 46.3; β-HCH = 46.5; γ-HCH = 54.2; δ-HCH = 16.9; aldrin = 16.7; dieldrin = 9.7; heptachlor = 15.9; heptachlor epoxide = 14.8; chlordane = 50.2; o,p′-DDT = 5.1; p,p′-DDT = 12.4; o,p′-DDT = 19.6; p,p′-DDD = 46.7; o,p′-DDE = 6.9; p,p′-DDE = 40.7 (.DDT = 55.0). Estimated dietary intakes (EDIs) from cheese consumption were compared to acceptable daily intakes (ADIs) for the pesticides where residues exceeded the MRL. EDIs calculated were in all cases below ADIs, and, therefore, based on the ADIs, there is no health risk involved in the consumption of cheese from Spain arising from organochlorine residues.  相似文献   

3.
A Geographical Information System (GIS) was combined with a model for simulating leaching and degradation of herbicides. The model uses first–order kinetics to simulate degradation, and a cascade model to simulate transport. This system was tested with data from a 16 km2 research catchment in northern Germany. Geometrical, topological, and soil data of this area were stored in a GIS. For the whole area, divided into small homogeneous sites (ecotopes), model runs were carried out. The system is able to handle data for all ecotopes automatically and to present calculated results on the behaviour of herbicides as distributed over time and depth for the area. An application of ethofumesate made in sugar–beet in spring and recropping of winter wheat after beet harvest was modelled. Degradation/sorption parameters were estimated from similar soils. Simulation results showed slower degradation in the sandy sites of the catchment, compared to the more loamy regions. Residues of herbicide remaining after beet harvest were greater than 20% of the applied dose in the sandy soils after 150 days. Hence, high risk of damage to the following crop of winter wheat was predicted. At the other sites residues remaining were between 2% and 20% of the applied dose. Einbindung eines Simulationsmodells zum Herbizidverhalten in ein Geographisches Informationssystem–Beispiel zur schlagspezifischen Anwendung Ein Geographisches Informationssystem (GIS) wurde mit einem Simulationsmodell für Herbizidabbau und –einwaschung kombiniert. Grundlage der Abbausimulation ist eine Kinetik 1. Ordnung, der Transport im Boden wird mit Hilfe eines Kaskadenmodells berechnet. Das System wurde in einem Intensiv–Untersuchungsgebiet (16 km2) in Norddeutschland getestet. Geometrische und topologische Daten der Fläche sowie Bodendaten sind im GIS gespeichert. Für die gesamte Fläche, die in kleine homogene Teilflächen (Ökotope) aufgeteilt wurde, wurden Simulationsberechnungen durchgeführt. Das System ist in der Lage, Daten für alle Ökotope automatisch bereitzustellen und die Ergebnisse zum Einwaschungs– und Abbauverhalten für die gesamte Fläche in ihrer Verteilung über Zeit und Tiefe darzustellen. Als Szenario wurde die Applikation von Ethofumesat in Zuckerrüben im Frühjahr mit einem Nachbau von Winterweizen nach der Rübenemte gewählt. Abbauund Sorptionsparameter waren in ähnlichen Böden ermittelt worden. Die Simulationsergebnisse zeigten einen langsameren Abbau in den sandigen Böden verglichen mit den lehmigen. In den sandigen Böden lagen die Rückstandsgehalte nach 150 Tagen übe 20 % der Ausgangskonzentration, wodurch ein hohes Nachbaurisiko für Winterweizen prognostiziert wurde. Für den Rest der Fläche lagen die Rückstände zwischen 2% und 20% der Ausgangskonzentration.  相似文献   

4.
BACKGROUND: Most insect‐resistant transgenic crops employ toxins to control pests. A novel approach is to enhance the effectiveness of natural enemies by genetic engineering of the biosynthesis of volatile organic compounds (VOCs). Before the commercialisation of such transgenic plants can be pursued, detailed fundamental studies of their effects on herbivores and their natural enemies are necessary. The linalool/nerolidol synthase gene FaNES1 was constitutively expressed from strawberry in three Arabidopsis thaliana accessions, and the behaviour of the aphid Brevicoryne brassicae L., the parasitoid Diaeretiella rapae McIntosh and the predator Episyrphus balteatus de Geer was studied. RESULTS: Transgenic FaNES1‐expressing plants emitted (E)‐nerolidol and larger amounts of (E)‐DMNT and linalool. Brevicoryne brassicae was repelled by the transgenic lines of two of the accessions, whereas its performance was not affected. Diaeretiella rapae preferred aphid‐infested transgenic plants over aphid‐infested wild‐type plants for two of the accessions. In contrast, female E. balteatus predators did not differentiate between aphid‐infested transgenic or wild‐type plants. CONCLUSION: The results indicate that the genetic engineering of plants to modify their emission of VOCs holds considerable promise for facilitating biological control of herbivores. Validation for crop plants is a necessary next step to assess the usefulness of modified volatile emission in integrated pest management. Copyright © 2012 Society of Chemical Industry  相似文献   

5.
I. TUNÇ  A. INCI 《EPPO Bulletin》1995,25(3):467-471
Observations were made on a caged batch of Schistocerca gregaria from a swarm which invaded Antalya (TR) on 1988-12-03. Females did not change their colour, and this might be a sign of lack of sexual maturity. Only 1.5% of the eggs deposited were viable. Mortality, apparently due to exhaustion during the crossing of the Mediterranean sea and unfavourable local winter conditions, and inviability of the eggs produced are proposed as detectable causes of the decline of S. gregaria in Antalya.  相似文献   

6.
Wang  Yao  Luo  Wenbo  Huang  Yun  Xu  Luyang  Yin  Yong 《植物病害和植物保护杂志》2017,124(1):67-71
Journal of Plant Diseases and Protection - The mixtures of 10&nbsp;% cyazofamid SC and 25&nbsp;% methiadinil SC were selected at different concentrations in root irrigation treatment of...  相似文献   

7.
Microbial degradation, organic synthesis and ecotoxicology were used to investigate the fate of diuron after spreading on soils. Quantitative biodegradation assays were performed with fungal strains, showing that diuron was degraded but not entirely mineralized. The modifications observed consisted in demethylation of the terminal nitrogen atom. The identified metabolites were synthesized in sufficient amounts to confirm their structures and determine their non‐target toxicity using four biotests. The two metabolites exhibited higher effects than parent diuron. This limited biodegradability and potential aquatic toxicity suggest that diuron is of higher environmental concern than previously recognized. © 2000 Society of Chemical Industry  相似文献   

8.
A citrus ringspot isolate from Star Ruby grapefruit (RS-SR) was mechanically transmitted to Chenopodium quinoa. RS-SR was partially purified by differential centrifugation, fractionation in a sucrose gradient, and agarose gel electrophoresis of selected fractions. Infectivity of concentrated extracts on C. quinoa was lost in individual fractions of the gradient, but it was recovered by combining a top and a bottom component. Both components contained a 48-kDa protein not found in similar preparations from healthy plants. After further purification the 48 kDa protein was detected at the top edge of the agarose gel. In the initial experiments a 38-kDa protein was found in the same fractions that later contained the 48-kDa protein. An antiserum obtained to the 38 kDa protein reacted in Western blots with both the 38- and the 48-kDa proteins, whereas another antiserum raised to the Florida isolate CRSV-4 (also containing a 48-kDa protein) did not react with the 38-kDa protein, indicating that the latter was probably a degradation product of the 48-kDa protein. Filamentous flexous particles were observed by serologically specific electron microscopy in crude extracts from RS-SR-infected C. quinoa plants. These results indicate that RS-SR is associated with a two-component virus similar to those associated with several psorosis and ringspot isolates, and serologically related to CRSV-4.  相似文献   

9.
A function that approximates the curve of the growth rate of the mycelium of the imperfect fungusSphaeropsis sapinea in relation to temperature is proposed. This function contains three free parameters, representing maximum growth rate, optimum temperature and shape of the curve. It was applied to data from an experiment with 27 isolates, in which the growth rate was measured in two replications at ten temperatures ranging from ?2 °C to 45 °C. Fitting the function to data from each isolate in each replication resulted in estimates of three parameters in which the information about the curve contained in the ten original observations is compressed. The estimates of the optimum temperature and of the shape were used in a further statistical analysis aimed at comparing the isolates and at ascertaining whether they could be divided into a few distinct groups, possibly related to different strains. The latter proved not to be the case.  相似文献   

10.
Kriss AB  Paul PA  Madden LV 《Phytopathology》2012,102(9):867-877
A multilevel analysis of heterogeneity of disease incidence was conducted based on observations of Fusarium head blight (caused by Fusarium graminearum) in Ohio during the 2002-11 growing seasons. Sampling consisted of counting the number of diseased and healthy wheat spikes per 0.3 m of row at 10 sites (about 30 m apart) in a total of 67 to 159 sampled fields in 12 to 32 sampled counties per year. Incidence was then determined as the proportion of diseased spikes at each site. Spatial heterogeneity of incidence among counties, fields within counties, and sites within fields and counties was characterized by fitting a generalized linear mixed model to the data, using a complementary log-log link function, with the assumption that the disease status of spikes was binomially distributed conditional on the effects of county, field, and site. Based on the estimated variance terms, there was highly significant spatial heterogeneity among counties and among fields within counties each year; magnitude of the estimated variances was similar for counties and fields. The lowest level of heterogeneity was among sites within fields, and the site variance was either 0 or not significantly greater than 0 in 3 of the 10 years. Based on the variances, the intracluster correlation of disease status of spikes within sites indicated that spikes from the same site were somewhat more likely to share the same disease status relative to spikes from other sites, fields, or counties. The estimated best linear unbiased predictor (EBLUP) for each county was determined, showing large differences across the state in disease incidence (as represented by the link function of the estimated probability that a spike was diseased) but no consistency between years for the different counties. The effects of geographical location, corn and wheat acreage per county, and environmental conditions on the EBLUP for each county were not significant in the majority of years.  相似文献   

11.
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12.
A virus was recovered by sap transmission from plants of several citrus species exhibiting or not symptoms of chlorotic dwarf (CCD), a disease recently reported from Eastern Mediterranean Turkey. The virus was identified as an isolate of olive latent virus 1 (OLV-1), originally described as a possible sobemovirus. The citrus isolate of OLV-1 (OLV-1/Tk) possesses biological, morphological, physico-chemical, and ultrastructural properties similar, if not identical to those of the OLV-1 type strain and is also serologically indistinguishable from it. In addition, OLV-1/Tk has many properties, especially physico-chemical, in common with serotypes A and D of tobacco necrosis necrovirus (TNV-A and TNV-D). However, OLV-1/Tk is only very distantly related serologically to both TNV-A and D, suggesting that it can be regarded as a distinct species in the genusNecrovirus. OLV-1/Tk could not be detected in citrus tissues by ELIS A or dot-blot molecular hybridization, probably because of the extremely low virus concentration. By contrast, limited virus recovery was obtained by sap inoculation and fair detection rates were afforded by PCR. OLV-1/Tk was identified in 54 of 92 (59%) citrus plants affected by CCD and in 14 of 49 (28%) symptomless plants. These results do not support the notion that there is a cause-effect relationship between OLV-1/Tk and CCD, even though the more frequent association of this virus with diseased plants remains intriguing.  相似文献   

13.
柽柳特麦蛾生物学特性的初步研究   总被引：2，自引：1，他引：2  
柽柳 (Ｔａｍａｒｉｘｓｐｐ .)自 1 9世纪初作为观赏植物从亚洲引入美国后 ,由于极强的适应能力和缺乏植食者的取食胁迫而迅速扩散。其中多枝柽柳 (ＴａｍａｒｉｘｒａｍｏｓｉｓｓｉｍａＬｅｄｅｂ .)、中华柽柳 (Ｔ .ｃｈｉｎｅｎｓｉｓＬｏｕｒ.)和密花柽柳 (Ｔ .ｐａｒｖｉｆｌｏｒａＤＣ .) ,特别是多枝柽柳已成为美国西南部的首要有害植物[1] 。从入侵植物原产地引进天敌控制其扩散蔓延 ,是一条经济、有效的生物防治方法。迄今 ,已报道取食柽柳属植物的麦蛾有 9个属 ,其中特麦蛾属 (Ｔｅｌｅｉｏｄｅｓ)有 2种 ,即Ｔ .ｂｒｕｃｉｎｅ…  相似文献   

14.
Kim WS  Geider K 《Phytopathology》2000,90(11):1263-1268
ABSTRACT A 3.3-kb fragment of genomic DNA from bacteriophage Phi-Ea1h encoding an amylovoran-directed depolymerase lyase was sequenced, and three open reading frames (ORFs) were detected. The first ORF could encode a lysozyme and the second a holin that may form a pore supporting cell lysis by the lysozyme. The third ORF encodes a protein of 657 amino acids and deletion mutation in this DNA fragment abolished extracellular polysaccharide (EPS)-degrading activity. A putative promoter and a ribosome binding sequence were located in front of the gene. A polymerase chain reaction product spanning the gene was inserted into multi copy plasmids including fusions with a Histidine-tagged sequence to facilitate its purification on a nickel nitrilotriacetic acid column. Maximal activity of the purified protein was observed between pH 4 and 5 at 52 degrees C. Visualized by staining with fluorescein isothiocyanate-labeled lectin from Abrus precatorious, the enzyme degraded the EPS-capsules of Erwina amylovora. In virulence assays, no symptoms were detected for a low inoculum of an E. amylovora strain when pear slices were soaked in a solution of depolymerase in contrast to control slices without addition of the enzyme. Furthermore, gfp- or lux-labeled E. amylovora cells were not propagated, when their amylovoran capsules were removed by the depolymerase. The enzyme could be a tool for biological control of fire blight.  相似文献   

15.
A pathogenic Pseudomonas syringae strain resistant to rifampicin and nalidixic acid was sprayed upon and colonized maple twigs and perennial ryegrass. The inoculated twigs were sampled at intervals of 2-3 weeks from July 1985 to September 1986, and epiphytic populations of the marked strain recovered during this time ranged from undetectable to 104 colony-forming units/g. The results showed that this strain of P. syringae could overwinter on maple twigs and potentially serve as a source of inoculum in the spring. Aerial dispersal was also investigated. The marked strain inoculated onto grass growing in pots was detected on medium in inverted petri plates, on maple leaves and with an Andersen sampler positioned from 12 to 100 cm above the grass. The number of detectable cells that dispersed vertically upwards was low even in the presence of wind, rain, or irrigation water. The marked strain inoculated onto maple branches was isolated from grasses under the inoculated trees, showing that P. syringae was dispersed downward. Lateral dispersal of the marked strain from inoculated to uninoculated trees was not detected. The identity of the antibiotic-resistant strain isolated from the trees and grasses was confirmed by DNA restriction-fragment profile analysis.  相似文献   

16.
No-till agriculture involves the use of granular pesticide formulations, chemically treated seeds, and pelleted baits. Some of these may accidentally kill birds. We have tested whether methyl anthranilate (MA), a known bird repellent, would eliminate consumption of a pelleted bait. In two laboratory experiments and an outdoor aviary trial, cowbirds (Molothrus ater Bodd.) were presented with pellets containing pesticide and MA, pellets containing pesticide but no MA, and carrier pellets without pesticide or MA. Consumption of any formulation was low, but the addition of MA significantly decreased bait loss in the laboratory, and prevented the disappearance of bait in the outdoor trial.  相似文献   

17.
Fusarium oxysporum (Fo) is an important soil-borne fungus that cause huge economic losses worldwide. Fungal-specific Common in Fungal Extracellular Membrane (CFEM) proteins are known to be involved in some important physiological processes associated with pathogenicity. To date, few Fo CFEM proteins have been characterized. The recent publication of several genomes of Fo has allowed us to conduct a genome-wide comparison analysis of CFEM proteins in Fo. In this study, we identified CFEM proteins for 12 different Fo formae speciales(f. sp) and obtained an average of 16 CFEM proteins for each Fo. The Fo CFEM proteins were classified into three groups (groups 1–3) according to structural features. Importantly, we identified a new conserved motif containing about 50 amino acids (DR motif) in group 1 members. CFEM proteins containing DR motif (CFEM_DR proteins) are remarkably conserved among Fo, and their number is greater in Fo compared with other fungi. We found the expansion of CFEM_DR proteins in Fo can be attributed to the segmental duplications in the genomes. Expression analysis revealed that CFEM_DR genes had a higher expression level in mycelium than conidia, and their expressions increased dramatically in the host roots at 3 days post inoculation, indicating that Fo CFEM_DR genes have roles while colonizing and infecting their hosts.  相似文献   

18.
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19.
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20.
Abstract

Saccharum spontaneum L. is an innocuous grass species of the Old World, but one of its ecotypes behaves as a pernicious weed in Central India. The species is believed to have evolved in the ecological mosaic of the sub-Himalayan valleys into a wide range of polyploids (2n = 40 to 128), from where its higher polyploids may have migrated into South-east Asia and Africa while the lower ones spread over the Indian sub-continent. The species shows much morphological diversity, and a remarkable plasticity and adaptation to environment. Its ecotypes propagate themselves variously, and many clones possess rhizomes for tiding over long dry seasons. The weed ecotype is one of the latter.

When a collection of S. spontaneum clones was grown in an experimental garden, most of the clones from the Himalayan river basins and the larger deltas showed no tendency to rhizome formation, while almost all occurring in the Central Indian plateau were highly rhizomic; the lower peninsular clones showed various degrees of predisposition.

These differences were seen to be associated with the presence or absence of soil droughts and long dry seasons in the original habitat. Apparently, natural selection for the rhizome character has taken place largely on the basis of this factor of the environment.

Genes for rhizomes may have arisen in the sub-Himalayan area and emerged into the Gangetic valley via areas felled indiscriminately and with inefficient agricultural follow-up. They may have accumulated under a high-selection pressure in the Central Indian plateau area and given rise to the pernicious weed ecotype here.

S. spontaneum does not yield to ordinary weeding; mechanised deep ploughing produced good results, but later the infestation returned. The weed may yield to irrigation, as this would dislocate it ecologically. Irrigation would boost its hot weather growth, which could be blade-harrowed away. A summer crop of rice or sunn hemp (for green manure) would keep the weed down until it is too late for it to grow. Pilot studies would show whether in this way the rhizomes could be starved out. Under the altered agro-ecological conditions, re-infestation may not succeed.  相似文献   

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