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1.
本研究确定了抑霉唑及其代谢产物咪唑乙醇的绝对构型,建立了一种基于超高效液相色谱-串联质谱检测柑橘不同部位抑霉唑和咪唑乙醇对映体的手性分析方法,并开展了柑橘贮藏过程中抑霉唑的选择性降解行为研究.柑橘(椪柑Citrus reticulata Blanco cv.Ponkan)果肉、全果和果皮样品通过乙腈(含体积分数1％ 的...  相似文献   

2.
Metabolism of imazalil (1-[2-(2,4-dichlorophenyl)-2-(2-propenyloxy)ethyl]-1H-imidazole) inPenicillium italicum isolates with a wild-type sensitivity and with various degrees of resistance to sterol demethylation inhibitors was studied in liquid cultures. The metabolite 1-[2(2,4-dichlorophenyl)-2-(2,3-dihydroxypropyloxy)ethyl]-1H-imidazole (R42243) was detected in the culture filtrate after prolonged incubation. The metabolism occurred in the propenyl side chain of imazalil probably through epoxidation and hydratation. This is the first report of such a conversion of imazalil in fungi. R42243 was much less toxic toP. italicum than imazalil. Therefore, the metabolism can be regarded as a detoxification step. Both wild-type and resistant isolates metabolized imazalil, but metabolism by resistant isolates was faster than by the wild-type isolate. This is probably caused by a relatively strong inhibition of growth of the wild-type isolate by the fungicide. Results indicate that the detoxification of imazalil does not operate as a mechanism of resistance. This conclusion was confirmed by the fact that resistant isolates showed cross-resistance to miconazole and R42243, which had a similar structure as imazalil except for the propenyl side chain.  相似文献   

3.
Methods are described for the extraction and analysis by gas-liquid and high-pressure liquid chromatography of the fungicide imazalil, 1-(β-allyloxy-2, 4-dishlorophenethyl) imidazole, on potatoes. Before storage, over 80% was recovered from potatoes treated with 0.01–3.0 mg imazalil kg?1, with a detection limit of 2 μg kg?1. Imazalil applied to potatoes at 10 g t?1 before storage decreased the incidence of gangrene (Phoma exigua), silver scurf (Helminthosporium solani), skin spot (Polyscytalum pustulans) and black scurf (Rhizoctonia solani), and was at least as effective as thiabendazole applied at 40 g t?1. At 1 g t?1 it also decreased skin spot and silver scurf. Incidence of black dot (Colletotrichum coccodes) was unaffected by these fungicide treatments.  相似文献   

4.
新烟碱类杀虫剂在苹果果实不同部位中的残留   总被引：1，自引：0，他引：1  
为了明确噻虫嗪、烯啶虫胺、吡虫啉、啶虫脒、噻虫胺和呋虫胺6种新烟碱类杀虫剂在苹果果实不同部位中的迁移转化规律，以10年生红富士苹果树为试材，分别于蚜虫发生期 (7月10日) 和果实采收前1 d (9月25日) 通过整株喷雾施药，随机取样，采用高效液相色谱仪测定，外标法定量，分析各杀虫剂在生长期套袋果实和不套袋果实及储藏期果实不同部位中的残留量及迁移规律。结果表明:在果实套袋情况下，施药后72 h内果实不同部位各新烟碱类杀虫剂的含量均呈现先逐渐上升而后下降的趋势，且在果皮中的残留量最低 (均低于0.08 mg/kg)，其中烯啶虫胺和吡虫啉在果皮中的残留量低于最低检测浓度，而在果柄和果肉中的残留量明显高于果皮中的，表明套袋果实中药剂主要来源于枝叶运输，经果柄进入果实后易向果肉累积；在果实未套袋情况下，施药后72 h 6种杀虫剂在果肉中的含量均高于套袋果实果肉中的，分别是套袋果实果肉中含量的7.75、3.52、3.36、6.57、2.92和3.06倍，表明套袋可有效降低果实中该类药剂的残留量。储藏试验结果表明:直接向果面喷施6种新烟碱类杀虫剂后，药剂主要存在于果皮中，施药后14和21 d在果肉中的含量均低于最低检测浓度，表明储藏期果皮为该类药剂的主要残留部位，且不易向果肉中转移。  相似文献   

5.
毒死蜱在梨果实不同部位的残留及消解动态   总被引：4，自引：3，他引：1  
为探明毒死蜱在梨果实不同部位的残留及消解规律,以20 a生鸭梨（Pyrus bretschneideri Rehd.cv.Yali）为试材,于果实生长期在套袋后向整株喷施48%毒死蜱乳油500倍液（有效成分960 mg/L）,分析毒死蜱向果实中的运输及分配规律;于果实成熟期在采收前向果面喷施48%毒死蜱乳油1 000倍液（有效成分480 mg/L）,分析采后毒死蜱在梨果实不同组织中的分布特征。采用乙腈萃取和GC-NPD检测方法,测定不同处理试材中的毒死蜱含量。结果表明,在果实套袋情况下,整株喷施毒死蜱后72 h内果实不同部位（果心除外）毒死蜱含量均呈现先逐渐上升而后下降趋势,其中果柄、果皮和果梗洼中毒死蜱最高含量值及其出现的时间分别为6.66 mg/kg（12 h）、2.42 mg/kg（24 h）和0.09 mg/kg（12 h）,表明套袋果实毒死蜱来源于枝叶运输,经果柄进入果实后易向果皮累积;而未套袋果施药后24和72 h果皮中毒死蜱含量分别为套袋果的12.56和7.29倍,表明套袋可有效降低果实中毒死蜱的残留量。于果实成熟期向果面喷施毒死蜱后7、14和25 d,果皮中毒死蜱残留量分别为15.54、13.70和12.81 mg/kg,占全果含量的100%,而果肉中毒死蜱残留量低于本检测方法的最低检出浓度（0.05 mg/kg）,因此果皮为果实中毒死蜱主要残留部位,且贮藏期果皮中毒死蜱不易向果肉扩散。  相似文献   

6.
Bobwhite quails were treated with imazalil for 8 weeks. The fungicide was given admixed in the food at 0, 100, 300, 500 and 1000 mg kg?1. Even at the highest dose tested, imazalil did not affect the liver weight or the hepatic microsomal protein content. In treated quails, no significant induction of cytochrome P-450 or NADPH-cytochrome c-reductase activity was observed. Furthermore, imazalil did not induce or inhibit 7-ethoxyresorufin or 7-ethoxycoumarin O-deethylase in quail microsomes. Only a slight but significant increase by 35% and 49% in aniline hydroxylase activity was measured for the 500- and 1000-mg kg?1 dose levels, respectively. After a drug-free period of one week, aniline hydroxylase activity returned to control values, indicating that the effect was fully reversible. It is concluded that imazalil does not induce or inhibit drug-metabolizing enzymes in the quail, even at doses which exceed by far the maximum levels currently used to dress seed under field conditions (100 mg kg?1).  相似文献   

7.
To evaluate whether the location of bacterial endophyte communities contributes to disease resistance in potato tubers ( Solanum tuberosum ), the population density, biodiversity and antibiotic activity of endophytic bacteria was examined from the tuber peel (periderm plus top 3 mm of tissue) of four cultivars (Russet Burbank, Kennebec, Butte and Shepody). There were no significant differences for population density of bacteria among the layers of peel examined and no cultivar × peel layer interaction. Endophytic bacteria from several layers of peel were challenged in in vitro bioassays to the soil-borne plant pathogens Fusarium sambucinum , Fusarium avenaceum , Fusarium oxysporum and Phytophthora infestans (mating types A1 and A2). In general, antibiosis of bacterial endophytes against these pathogens was significantly higher ( P  = 0.01) in isolates recovered from the outermost layer of tuber peel and decreased progressively toward the centre of the tuber. Antibiosis against P. infestans was variable, with a progressive decrease in antibiotic activity from outer to inner layers of peel occurring in cvs Russet Burbank and Kennebec only. For antibiosis there were significant cultivar × peel, and cultivar × pathogen interactions ( P  = 0.01). In all cases the inhibitory activity of endophytic bacteria was significantly greater ( P  = 0.01) against the A1 than the A2 mating type of P. infestans . In four of seven cases, where the same species of bacteria were recovered from all three peel layers, antibiosis to pathogens decreased significantly ( P  = 0.01) with depth of recovery (from the periderm to inside the tuber), indicating that in certain communities of endophytic bacteria, defence against pathogens may be related to bacterial adaptation to location within a host and may be tissue-type and tissue-site specific.  相似文献   

8.
An electron capture gas-liquid chromatographic method is described for the analysis of the fungicide imazalil,a 1-(β-allyloxy-2, 4-dichlorophenethyl)imidazole, in citrus fruit. Recoveries were 80–95% from citrus fruit fortified at 0.50–2.0 mg/kg, with a limit of detection of 0.01 mg/kg.  相似文献   

9.
Applying thiabendazole to potato seed tubers affected with silver scurf caused by Helminthosporium solani sensitive to thiabendazole decreased the severity of disease on progeny tubers at harvest, but about 50% of the isolates from these were resistant to the fungicide. The disease was not decreased when samples of the progeny tubers were treated with thiabendazole and planted in the following year, and the incidence of resistant isolates increased. Resistant isolates continued to be present when tubers were planted in the next 2 years without fungicide treatment. Treatment with a mixture of thiabendazole and imazalil also decreased the disease and fewer isolates were resistant than when treated with thiabendazole alone, although the proportion increased after treatment with the mixture in the following year. When seed tubers were infected with thiabendazole-resistant H. solani , silver scurf on progeny tubers was not affected by thiabendazole applied to the seed tubers but was decreased by the mixture of thiabendazole and imazalil. Imazalil was equally effective against H. solani sensitive or resistant to thiabendazole.
Some isolates of H. solani had grey aerial mycelium and of 516 of these isolates obtained in 4 years 29% were resistant to the fungicide. Other isolates produced small, black colonies and their frequency increased with thiabendazole treatment of seed tubers. Of 244 of these isolates, 62% were resistant.  相似文献   

10.
The metabolism of fosetyl-aluminium to phosphonic acid in the peel of citrus fruit has been studied by gas chromatography using a nitrogen-phosphorus detector and also with a flame photometric detector. At the same time the phosphonic acid residues remaining in the peel and the pulp of citrus fruit, as a result of the application of aqueous solutions of fosetyl-aluminium at 2.5 g litre?1 to trees prior to harvest was determined.  相似文献   

11.
The effects of different incubation conditions on toxicity and uptake of imazalil by mycelium of a wild-type (003) and fungicide-resistant (R264) strain of Aspergillus nidulans were determined. In agar plate and liquid shake culture, imazalil was 200 and 40 times less toxic to the R264 strain, respectively, than to the wild-type strain. Inhibition of C-4 desmethyl sterol (ergosterol) biosynthesis occurred rapidly in mycelium of both strains at minimum growth inhibitory concentrations. Imazalil was neither detoxified nor converted into a toxic compound by mycelial suspension. Increased uptake of imazalil by the two strains occurred as concentrations of the fungicide were increased. However, the percentage uptake of imazalil by the wild-type strain was highest at the lowest concentration. These results suggest that binding in the wild-type strain involved a small number of high-affinity sites which became saturated as fungicide concentrations increased; and that at higher concentrations considerable nonspecific binding occurred in both strains. Uptake of imazalil during the initial 10 min of incubation was considerably lower in resistant than in the wild-type strain. However, upon prolonged incubation, both strains took up near equal amounts of fungicide. Uptake of fungicide by both strains was not inhibited by incubation at low temperature but was stimulated by respiratory inhibitors. These data support, in part, the hypothesis that resistance to imazalil, as reported previously for fenarimol (M. A. de Waard and J. G. M. van Nistelrooy, Pestic. Biochem. Physiol. 13, 255 (1980)), is based on reduced uptake of fungicide by mycelium of the resistant mutant.  相似文献   

12.
为明确柑橘汁加工过程中吡唑醚菌酯的残留动态,于2019年在湖南省洪江市和重庆市江津区两地以普通甜橙为研究对象,采用40%吡唑 ? 咪鲜胺水乳剂按5倍最高推荐剂量(有效成分166.7 mg/kg) 施药3次,按照橙汁典型商业化加工工艺过程进行加工,采用QuEChERS前处理方法结合高效液相色谱-串联质谱(HPLC-MS/MS)检测吡唑醚菌酯的残留量。方法确证结果表明:在0.0025~0. 5 mg/L(皮精油基质为0.005~1 mg/L)范围内,吡唑醚菌酯的基质匹配标准曲线线性关系良好(相关系数大于0.9905)。在0.01、0.1和2 mg/kg (皮精油基质为0.2、2和20 mg/kg) 3个添加水平下,吡唑醚菌酯在柑橘加工产品及清洗液中的平均回收率为63%~110%,相对标准偏差(RSD)为1.3%~9.6%。柑橘汁加工试验结果表明:榨汁过程[加工因子(PF)的最佳评估值为<0.02]是降低吡唑醚菌酯残留的高效途径,吡唑醚菌酯易在皮渣(PF为1.2)及皮精油(PF为15.6)中富集。研究结果可为吡唑醚菌酯的膳食风险评估提供参考。  相似文献   

13.
Automated conductance measurements in polypectate medium were used for the detection of pathogenic soft rot Erwinia spp. in potato peel extracts. The detection threshold for Erwinia carotovora subsp. atroseptica (Eca) in inoculated peel extracts was ca. 104 colony forming units (cfu) ml-1 when samples were considered positive on the basis of a response within 48 h at 20 °C. Detection of E. chrysanthemi (Ech) was less sensitive, only 105 cfu ml-1 peel extract were detected within 36 h at 25 °C. The linear correlation between detection times in conductimetry and inoculum levels of Eca and Ech in peel extracts was used for a quantitative estimation of Eca and Ech in naturally contaminated peel extracts. Samples giving a positive conductimetric response had to be confirmed with an enzyme-linked immunosorbent assay (ELISA) or polymerase chain reaction (PCR) for the presence of Eca and Ech, because E. carotovora subsp. carotovora (Ecc) also generated a conductance response. Conductimetry was sensitive and efficient for detection of contamination levels of Eca higher than 104 cfu ml-1 peel extract. For Ech, conductimetric detection was less sensitive and inefficient due to low contamination levels of Ech and the presence of high numbers of Ecc in many samples after enrichment, which interfered with the test. Immunofluorescence cell staining (IF) combined with enrichment and immunofluorescence colony staining (IFC) were suited to detect and quantify low numbers of Eca and Ech at less than 104 cfu ml-1 in peel extracts. However, since false positive and negative reactions in serology were observed, the use of PCR after enrichment, or in combination with IFC to confirm positive results, was required for accurate detection.  相似文献   

14.
The effect of fosetyl-aluminium on the control and spread of brown rot disease Phytophthora citrophthora in post-harvest citrus fruit was studied in laboratory and semi-commercial experiments. Aqueous solutions of fosetyl-aluminium at 5 to 10 g a.i. litre?1 controlled the fungus even when applied 3 days after inoculation at 17°C. No mycelia developed on the peel surface of treated fruit. The fungicide exerted a good prophylactic effect on healthy fruit, protecting them during storage from contact inoculation. Fosetyl-aluminium also showed a fungitoxic effect in vitro and in vivo on other fungi which developed in harvested citrus fruits. Residue levels of phosphoric acid in the treated fruit were higher when the fungicide was incorporated in the wax coating the fruit than when applied in aqueous solution, and levels were lower in the pulp than in the peel. It is concluded that fosetyl-aluminium is a suitable commercial post-harvest treatment for control of brown rot in citrus fruits.  相似文献   

15.
Isolates ofPenicillium italicum with differential levels of resistance to imazalil were obtained via step-wise mass selection of conidia of the fenarimol-resistant isolate E300-3 on imazalilamended PDA. Three out of five selection steps were successful. The resistance level to imazalil of isolates acquired after the two last selection steps was on average 122 and 197. The differential level of resistance was also apparent in decay control on oranges by imazalil inoculated with the various isolates. The isolates showed a similar cross-resistance pattern to other fungicides which inhibit C-14 demethylation of sterols (DMIs), although the level of resistance to these fungicides was significantly higher. All isolates displayed negatively-correlated cross-resistance to tridemorph and dodine. Most isolates had a normal virulence on oranges. In competition experiments with mixed-inocula of the wild-type and a resistant isolate, the proportion of the wild-type increased in successive generations on untreated oranges and the proportion of the resistant isolate increased on imazalil-treated oranges. The lower competitive ability of the resistant isolate on untreated oranges may be due to a decrease in spore production as compared with the wild-type.Since isolate E300-3 was obtained in two selection steps on fenarimol-amended PDA, the isolates obtained in the last selection steps on imazalil-amended PDA may have at least five different genes for resistance to DMIs. This is consistent with resistance to DMIs being under polygenic control, with the genes involved having an additive interaction, although this is not the only possible explanation of the results.  相似文献   

16.
嘧霉胺对采后柑橘绿霉病的防治效果   总被引：1，自引：0，他引：1  
在实验室和贮藏库条件下,对嘧霉胺单剂、嘧霉胺与抑霉唑或嘧霉胺和咪鲜胺混剂防治柑橘绿霉病的效果进行了评价。室内实验结果表明:采用500或1 000 mg/L嘧霉胺单剂、500 mg/L嘧霉胺+500 mg/L抑霉唑或500 mg/L嘧霉胺+500 mg/L咪鲜胺混剂在接种后12~18 h进行浸果处理,对由抑霉唑抗性或敏感菌株引起的绿霉病均有显著的防治效果,防效超过94%;500或1 000 mg/L 的抑霉唑对敏感菌株的防效在93%以上,但对抗性菌株的防效低于70%。贮藏库防效试验结果表明:在具抑霉唑抗性菌系的贮藏库中,上述质量浓度的嘧霉胺单剂、嘧霉胺与抑霉唑、或嘧霉胺与咪鲜胺混剂对绿霉病的防治效果明显优于抑霉唑单剂;而在不具抗抑霉唑菌系贮藏库中的防效则与抑霉唑相当。由此认为:嘧霉胺可作为抑霉唑的替代药剂应用于柑橘的采后处理,其推荐使用质量浓度为500~1 000 mg/L,可单独使用,也可与抑霉唑或咪鲜胺混合使用。  相似文献   

17.
Differential accumulation of [14C]imazalil and [14C]fenarimol by germlings of wild-type and DMI-resistant isolates ofPenicillium italicum was studied at various pH values. At pH 7 and 8 the low-resistant isolate E300–3 accumulated 22% and 35%, respectively, less imazalil than the wild-type isolate W5. Imazalil accumulation at pH 5 and 6 was similar. Isolate E300–3 also accumulated less fenarimol as compared with the wild-type isolate. This difference was much more obvious than for imazalil and was observed at all pH values tested. Differences in accumulation of both imazalil and fenarimol between low (E300–3), medium (H17) and high resistant (I33) isolates were not observed. These results suggest that decreased accumulation of DMIs is responsible for a low level of resistance only and that additional mechanisms of resistance might operate in isolates with a medium and high degree of resistance. With all isolates fenarimol accumulation was energy-dependent. This was not obvious for imazalil.The wild-type and DMI-resistant isolates had a similar plasma membrane potential as determined with the probe [14C]tetraphenylphosphonium bromide ([14C]TPP+). Various test compounds, among which ATPase inhibitors, ionophoric antibiotics and calmodulin antagonists, affected the accumulation of [14C]TPP+, [14C]imazalil and [14C]fenarimol. No obvious correlation between the effects of the test compounds on accumulation levels of the fungicides and [14C]TPP+ could be observed. These results indicate that the plasma membrane potential does not mediate the efflux of DMI fungicides byP. italicum.  相似文献   

18.
Imazalil had no effect on the initial growth of mycelia of Penicillium italicum (for 10 hr) or Aspergillus nidulans (for 2 hr). In P. italicum during this period neither respiration nor cell permeability was affected, but uptake of [32P]phosphate, [14C]leucine, or [14C]uridine was partially inhibited. The initial (5 hr) inhibition of substrate uptake coincided with a 50% reduction in ergosterol content. Within 0.5 hr, incorporation of [14C]acetate into C-4-desmethyl sterols was strongly inhibited in mycelia of A. nidulans treated with 0.5 μg/ml of imazalil. However, radioactivity in C-4-methyl and dimethyl sterols exceeded that of control cultures. Concentrations of imazalil as low as 0.005 μg/ml caused short-term (1 hr) declines of incorporation into desmethyl sterols and increases into the C-4-methyl and dimethyl sterols. Incorporation into phospholipids, triglycerides, and free fatty acids was not affected. These data suggest that the primary antifungal action of imazalil is inhibition of demethylation in the biosynthesis of ergosterol.  相似文献   

19.
Mutant strains of Aspergillus nidulans have been isolated which display a low level of resistance to imazalil, a recently developed systemic fungicide. Agar growth tests showed that A. nidulans is about three times as sensitive to imazalil when growing on supplemented minimal medium (SM) as compared with complete medium. This effect was reduced by adding glutamic acid to the SM.Imazalil resistance was found to be based on a multigenic system; 21 single gene mutations define 8 loci which were allocated to 6 different linkage groups. Mutations at different loci lead pleiotropically to one or more of the following properties: hypersensitivity or resistance to acriflavin, cycloheximide and neomycin, resistance to chloramphenicol and fenarimol, and to cold sensitivity. Of 120 cycloheximide-resistant strains isolated, 98 were also imazalil-resistant.Recombination analysis of different imazalil-resistant strains with mutations at three loci resulted in additive effects, giving strains with a high level of resistance to imazalil.The results indicate that imazalil may interfere either with protein synthesis like cycloheximide, chloramphenicol and neomycin or with synthesis or function of cell membranes. Interference with cell membrane synthesis might lead to altered sterol composition, resulting in selective permeability to different compounds.  相似文献   

20.
Isolates of Pyrenophora graminea resistant to organomercury were obtained from barley crops in England and Scotland in 1984–6. Resistant isolates were approximately 100 times less sensitive in vitro than sensitive isolates to phenyl mercuric acetate (PMA), but the difference was only four times for methoxyethyl mercuric acetate (MEMA). In small-plot field trials, seed treatment with either PMA or MEMA gave good control of leaf stripe disease caused by organomercury-sensitive strains of P. graminea but neither compound gave commercially acceptable control of resistant strains. Fungicides with different modes of action (triadimenol + fuberidazole, flutriafol + ethirimol + thiabendazole, carboxin-+- thiabendazole + imazalil, and guazatine + imazalil) were effective against organomercury-sensitive and organomercury-resistant strains. The few cases of resistance found do not justify a change from the use of organomercury as the standard seed treatment for barley.  相似文献   

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