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1.
Treatment of human erythrocytes with 5 × 10?5M captan or captafol caused a rapid increase in the efflux of intracellular potassium. Captafol had a more pronounced effect than captan on cation permeability. Captafol also decreased anion permeability whereas captan did not affect this process. Glutathione (5 × 10?4M) had little effect in reducing potassium efflux when added to the cells after they were incubated for 1 h with captan or captafol, but it was effective in reducing the potassium loss when added to the cells prior to their treatment with the fungicides. Captafol caused an increase in osmotic fragility of the cells. Incubation of the cell membranes with captafol resulted in the liberation of a small fraction of membrane phospholipids, whereas captan produced no effect. Both the fungicides readily reacted with the sulfhydryl groups in the isolated membrane; 31.5 and 45.7% of the membrane sulfhydryl groups had disappeared following treatment with captan and captafol, respectively. It is suggested that the reaction of captan or captafol and/or their reaction products with the sulfhydryl and amino groups of the red cell membrane protein produces changes in the structure of the membrane with consequent alteration in its permeability.  相似文献   

2.
Phthalimide fungicides (captafol, captan and folpet) enhanced the accumulation of fenarimol by the mycelium of a wild-type strain and a fenarimol-resistant strain of Aspergillus nidulans. The accumulation is ascribed to inhibition of active efflux of fenarimol from the mycelium. It is assumed that the synergistic action observed between the phthalimide fungicides and fenarimol with respect to fungitoxicity, was caused by the increased accumulation of fenarimol.  相似文献   

3.
The procedures involve the removal of captafol, captan or endosulfan spray deposits from the plant surfaces with solvent and their measurement by g.l.c. In contrast to residue analysis, clean-up procedures are avoided and the speed of the methods enable large numbers of samples to be processed in the monitoring of initial spray deposits and the subsequent redistribution or loss in relation to the efficiency of spray application techniques. Recoveries of captafol and captan suspension deposits from glass were greater than 96%: recoveries of emulsion deposits from plant surfaces were greater than 95% for captafol, 93% for captan and 96% for endosulfan.  相似文献   

4.
A method is described for the simultaneous determination of residues of five fungicides used for foliar treatment of apple and pear trees, and for postharvest application. After extraction, the mixture of these fungicides is cleaned-up on a ‘SEP PAK C18’ cartridge and the components determined by gas-liquid chromatography with electron-capture detection. The minimum detectable amounts in apples and pears, on a fresh weight basis, were 0.005mg kg−1 for vinclozolin, 0.010mg kg−1 for captan, folpet and iprodione, and 0.020 mg kg−1 for captafol. The percentage recovery for each fungicide (calculated by analysing four samples of untreated apples and pears, to which varying concentrations of each active ingredient had been added) varied for vinclozolin between 70.0 and 89.2, for captan between 72.0 and 83.8, for folpet between 73.0 and 93.0, for captafol between 70.8 and 91.8, and for iprodione between 75.1 and 97.1.  相似文献   

5.
Addition of cysteine to the fungicides captan, folpet, dichlofluanid and captafol antagonizes the activity of these fungicides and results in the formation of volatile fungitoxicants. There is no relationship, however, between the vapour action upon reaction with cysteine and the fungitoxicity of these compounds.Samenvatting Cysteine heeft een antagonerend effect op de werking van captan, folpet, dichlofluanid en captafol (Tabel 1). Bij proeven in afgesloten ruimtes (twee petri schaaltjes, waarvan de één ongekeerd op de ander, Fig. 1) bleek vooral captan als gevolg van een reactie met cysteine een voorFusarium culmorum toxische damp af te geven, folpet deed dit daarentegen niet, en de twee andere fungiciden alleen in de hoogste concentratie (Tabel 1, Fig. 1). Er is dus weinig verband tussen de fungicide werking en de productie van fungicide dampen als gevolg van de reactie met thiolen.  相似文献   

6.
The effects on DNA synthesis of the fungicide captan and several structurally related compounds were investigated in isolated bovine liver nuclei. Captan, folpet, captafol, and trichloromethanesulfenyl chloride inhibited DNA synthesis to the same degree with ID50 values of approximately 50 μM in a 40-min assay. The inhibition is concentration dependent and the degree of inhibition increases with time. Studies with structural analogs of captan indicated that inhibition of DNA synthesis by captan is mediated through the trichloromethylthio moiety of the captan molecule. In addition, the data indicate thiophosgene is probably not the toxic species involved in the inhibition of DNA synthesis. The isolated nuclei used in this study were shown to exhibit only a single DNA polymerase activity which was determined to be of the β or low-molecular-weight type. In addition to its inhibition in intact nuclei, captan inhibited the activity of the β polymerase in nuclear extracts as well as in partially purified enzyme preparations. These results indicate that captan inhibits DNA synthesis in our preparation of isolated nuclei by acting directly on the DNA polymerase-catalyzed reaction rather than by causing a nonspecific or indirect effect in the nuclear system such as alterations in the nuclear membrane or aggregation of the nuclei. The site of captan's inhibitory action is the DNA polymerase molecule. The interaction of captan with the polymerase results in irreversible inhibition of the enzyme. Interaction of captan with the template, if it occurs, does not appear to be involved in mediating the inhibition.  相似文献   

7.
Anthracnose stain on Clementine tangerine and grapefruit, caused byColletotrichum gloeosporioides, is described. Among the fungicides bioassayed against this organism Bordeaux mixture was the most effective copper compound; potent organic compounds were captafol, captan, chlorothalonil, maneb and mancozeb. Bioassay evaluation of fruit treated in the grove revealed that the protection and lasting effect of captafol and Bordeaux mixture were superior to those of chlorothalonil and maneb. Effective field control was achieved even with one prophylactic treatment in July with copper-containing fungicides.  相似文献   

8.
Heterokaryosis is an important mechanism which provides genetic variability increase in filamentous fungi. In order to assess the diversity of vegetative compatibility reactions existing among Colletotrichum acutatum isolates derived from different hosts, complementary nit mutants of each isolate were obtained and paired in all possible combinations. Vegetative compatibility groups (VCG) were identified among the isolates according to their ability to form viable heterokaryons. Seven VCGs were identified among the isolates, one of which contained isolates from different hosts. VCGs 2 and 6 contained two and three members, respectively; VCG-3 contained four members, and four VCGs (1, 4, 5, and 7) contained a single one. This study shows, for the first time, the isolation and the parasexual segregation of a heterozygous diploid sector derived from the heterokaryon formed with nit mutants from VCG-6. Diploid, named DE-3, showed nit+ phenotype and growth rate similar to the parental wild isolate. When inoculated in the presence of the haploidizing agent benomyl, the diploid strain produced parasexual haploid segregants exhibiting the nit phenotypes of the crossed mutants. Since viable heterokaryons and diploid may be formed among vegetative compatible isolates of C. acutatum, this study suggests that the parasexual cycle may be an alternative source of genetic variability in C. acutatum isolates.  相似文献   

9.
Seeds of perennial ryegrass Lolium perenne treated with four fungicides, benomyl, captan, iprodione and metalaxyl, used singly and in all combinations were sown in soil in pots. The soil was maintained at a low moisture content to predispose the seedlings to pre-emergence infection by soil-borne fungi. Thirteen of the fifteen fungicide treatments significantly increased seedling emergence and all but one contained benomyl and/or captan. In another pot experiment, a combination of benomyl and captan was tested against four similar treatments, carbendazim+captan, thiabendazole+captan, thiabendazole+metalaxyl and thiabendazole+thiram and also drazoxolon. Only benomyl+captan and drazoxolon did not increase seedling emergence significantly. A natural infection of the seedlings by powdery mildew Erysiphe graminis was reduced significantly by all treatments except thiabendazole+thiram and drazoxolon. Only car-bendazim+captan significantly increased the dry weight of seedlings per pot 98 days after sowing. Benomyl+captan seed treatment significantly increased seedling emergence in 9 of 16 soils collected from widespread sites. One perennial ryegrass cultivar, Parcour, was used in the above experiments and in a comparison with 12 other diploid cultivars its response to benomyl seed treatment was about mid-range.  相似文献   

10.
The genetics and biochemistry of oxidative resistance to diazinon were investigated in a diazinon-resistant strain of the house fly, Musca domestica L. The resistant strain was crossed with a multimarker susceptible strain and substrains containing portions of the resistant strain genome were prepared. Resistance, microsomal oxidase, and cytochrome P-450 spectral characteristics were then compared in the different strains. The major gene for resistance to diazinon is semidominant and is located on chromosome II, 13 crossing over units from the recessive mutant stubby wing. Additional resistance genes occur on chromosome II and on other chromosomes as well. Resistance to diazinon was introduced into a susceptible mutant-marked strain via genetic crossing over. Increases in parathion oxidase, total and P-450-specific N- and O-demethylase activity, and resistant strain type I binding spectrum were introduced along with resistance, indicating genes controlling these parameters and resistance are either identical or closely linked. No increase in activity of cytochrome P-450 itself was introduced into the mutant strain. Additional genes controlling the amount of cytochrome P-450 and several spectral changes characteristic of the resistant strains are apparently controlled by genes located at different loci on chromosome II. Resistance factors on other chromosomes are also present, but were not characterized.  相似文献   

11.
Phylloplane micro-organisms may metabolise substances present on the leaf surface, they may interact with leaf pathogens and they may be involved in the process of senescence. The effects of fungicides on many leaf saprophytes are, however, largely unknown. Studies under both field and laboratory conditions have indicated that wide spectrum protectant fungicides, such as captan, captafol and zineb, are as effective against the saprophytic flora as they are against plant pathogens. If the leaf surface microflora is restricted by fungicides then antagonism towards pathogens will also be reduced, but beneficial results may ensue if the microbial impact on senescence is lessened. Field trials with barley have demonstrated that it is possible to delay senescence by using fungicide sprays.  相似文献   

12.
ABSTRACT The comovirus Bean pod mottle virus (BPMV) is widespread in the soybean-growing regions in the United States. It has a bipartite genome consisting of RNA1 and RNA2, which are encapsidated separately. We previously have reported the occurrence in nature of two distinct subgroups of BPMV strains (subgroups I and II), as well as reassortants between the two subgroups. Here, we report the isolation and molecular characterization of naturally occurring partial diploid reassortant strains, which are diploid for RNA1 and haploid for RNA2. Whereas the RNA1s of the partial diploids are derived from two distinct strain subgroups (I and II), the RNA2 is derived from either subgroup I or II. The partial diploid strains induced strikingly severe symptoms on soybean, which could be explained based on the presence of two distinct RNA1s in the same plant. This conclusion was supported by the finding that pseudo-recombinants constructed with two diverse RNA1s induced very severe symptoms on soybean that mimicked those produced by the naturally occurring partial diploids. No enhancement of symptom severity was observed with pseudorecombinants constructed with closely related RNA1s. Likewise, no enhancement of symptom severity was noted with pseudo-recombinants that are diploid for RNA2 and haploid for RNA1. The potential role of genetic reassortment in the epidemiology and pathogenesis of BPMV is discussed.  相似文献   

13.
In two trials established between 1983 and 1990, copper oxychloride and prochloraz-manganese applied at 5 and 50% leaf-fall were as effective as phenylmercury nitrate, formerly used (but now banned) for the control of leaf-scar infection by Nectria galligena. However, prochloraz-manganese has not been developed for use on fruit. Autumn application of carbendazim gave inadequate control and thiophanate-methyl, bitertanol and fenpropimorph were ineffective. Carbendazim applied as a spring-summer treatment reduced canker development to a similar level to a spring-summer dodine scab programme plus autumn copper oxychloride. Summer carbendazim + captafol was an outstandingly effective treatment, but since this trial the use of captafol as a fungicide in the UK has been prohibited. In the absence of an effective autumn treatment, penconazole alone or with captan, and myclobutanil preblossom with myclobutanil alone or with mancozeb post-blossom tended to be less effictive than the standard programme (dodine pre- and dithianon post-blossom). Carbendazim mixed with an effective scab fungicide such as dithianon therefore remains the recommended treatment in an orchard with a serious canker problem. In orchards where there is a limited risk of canker, a spring-summer scab fungicide programme should prevent N. galligena infection at this time of year, with copper oxychloride applied at leaf-fall, particularly after wet weather, to prevent leaf-scar infection.  相似文献   

14.
A study was conducted concerning the inhibition of calf thymus nuclear DNA synthesis by captan. Captan was shown to be toxic to the in vitro incorporation of [3H]dTTP into calf thymus DNA, with an ID50 value of 0.16 mM being measured. This inhibition was determined to be independent of Mg2+ concentration. Although intact nuclear activities were affected, the soluble DNA polymerizing activity isolated from calf thymus nuclei exhibited no inhibition when exposed to captan. Treatment of purified calf thymus DNA with 10?5 and 10?4M captan caused an elevation of the Tm by 2 and 6°C, respectively. The inhibitory characteristic of captan on DNA polymerizing activities and the influence of this compound on the thermostability of DNA indicate a mechanism of inhibition which is located in the nucleus and is possibly related to the template function of DNA and/or with the nuclear DNA polymerizing enzymes.  相似文献   

15.
The DDT-resistant housefly strain, Fe, known to resist DDT by biochemical oxidation, is also resistant to carbamate insecticides and has a high in vitro microsomal epoxidase activity. The purpose of this investigation was to determine whether the DDT resistance, associated with chromosome V, is also responsible for the resistance to carbamates and for the high epoxidase levels. Genetic procedures for segregating the R factors were employed using a multimarker insecticide susceptible strain designated acbco. The technique involved backcrossing the F1 hybrid of the resistant and susceptible parents to the susceptible parent. The genotypes with a single R chromosome from the Fc parent were retained for further development as substrains and for toxicological and biochemical studies.These studies revealed that both resistance to the carbamate insecticide, propoxur, and the high in vitro microsomal epoxidation of aldrin were lost during the genetic isolation of the R factors. However, the resistance to DDT, associated with chromosome V, was present in the substrain carrying this chromosome from the Fc parent. All of the substrains were induced five- to seven-fold, by feeding phenobarbital at 1% in the diet for 3 days.Additional substrains synthesized from the substrains carrying chromosomes II and V or III and V from the Fc parent did not possess sufficient propoxur resistance or aldrin epoxidase activity to account for that present in the R parent.The interpretation of these rseults is that neither the carbamate resistance nor the microsomal epoxidase of the Fc strain is due to the factor which oxidizes DDT. Furthermore, the factor responsible for the high microsomal epoxidase activity is not due to a single chromosome such as chromosome II which is the case in other housefly strains with high oxidase activities.  相似文献   

16.
Respiration and growth of a diploid strain of Ustilago maydis, heterozygous at the oxr-1 locus for resistance to carboxin and carboxin analogs, were less sensitive to the fungicide than the corresponding processes in the wild type haploid. Data on the inhibition of succinate-2,6-dichlorophenolindophenol reductase indicate that the mitochondria of the heterozygous diploid probably contain a mixture of carboxin-sensitive and carboxin-resistant succinic dehydrogenase complexes. This hypothesis is supported by the results of temperature aging experiments: When mitochondria of the heterozygous diploid were subjected to incubation at 30°C which destroyed the enzyme activity of mitochondria from the mutant haploid, the remaining succinate-2,6-dichlorophenol-indophenol reductase activity exhibited a carboxin sensitivity similar to that of mitochondria from the wild type haploid.Carboxin gave very good control of corn smut in seedlings artificially inoculated with two wild type compatible strains but not when both strains were mutant for carboxin resistance, which indicates high resistance in the dicaryon. In a heterozygous cross, the dicaryon seemed to exhibit considerable resistance, if sufficient time was allowed for its formation between inoculation and carboxin treatment of soil.  相似文献   

17.
A critical test of fungicidal activity against the wound pathogen Glomerella cingulata f.sp. camelliae on camellias involved the application of a conidial suspension to scratches on detached leaves, treated with fungicide 24 h previously. In this test, prochloraz at 250–500 μg/ml a.i. in both EC and manganese WP formulations was highly effective, inhibiting leaf rotting by 90–100% compared with 55% or less in some tests with benomyl, chlorothalonil and captafol at 500–1000 μg/ml and captan at 1200 μg/ml. Prochloraz gave similar protection to leaves when applied to whole plants. Protection was less, especially on older leaves, when wounding and inoculating were delayed by 7 or more days after treatment. Prochloraz did not prevent all infection through comparatively large wounds, e.g. leaf scars, made on stems 24 h after treatment.
Poor control of the disease in a nursery was not due to resistance of the pathogen to benomyl; in vitro tests failed to detect full resistance at this time. Under nursery conditions a statutory policy of destroying infected plants and spraying the remainder with prochloraz or prochloraz manganese (both at 500 μg/ml), alternating with benomyl (500 μg/ml) on a weekly basis apparently prevented spread of the disease to healthy plants.  相似文献   

18.
Abstract

Fungicide spray trials showed that high volume applications (1121 lha) of mancozeb, captafol and vondozeb reduced foliage and stem disease and substantially increased marketable yields of rain-fed tomatoes in northern Nigeria. The results suggest that captafol had a more persistent fungicidal action as there was no yield difference between the 7 and 14 day frequencies of application. U.I.v. methods (<12 l/ha) using three fungicides were compared with high volume treatments. The u.I.v. captafol treatment was particularly effective. An assessment was made of droplet distribution in relation to atomiser disc rotation speed and the height of carriage of the sprayer.  相似文献   

19.
The effects of two pesticides, dieldrin and captan, upon the growth and macromolecular syntheses of the vegetative cells of Dictyostelium discoideum strain Ax-2 were investigated. Dieldrin at a concentration of 5 μg/ml inhibited growth as well as the synthesis of RNA, DNA, and protein, while as little as 1 μg/ml of captan produced the same effects. After a 1-hr exposure to either pesticide, all macromolecular syntheses ceased. Within a period of 5 to 10 hr the amoebae began to shrink, and eventually some lysis occurred. Lysis was most pronounced in cells incubated with captan. When the amoebae were grown in the presence of 5 μg/ml of either pesticide and then washed and resuspended in fresh medium, the effects on growth were annulled. No growth inhibition was observed when 0.05 M cysteine was added prior to the addition of 5 μg/ml of captan. Further experimentation to study possible degradation effects of these two synthetic pesticides upon RNA and protein molecules showed that breakdown of these macromolecules into TCA-soluble units did not occur. Preliminary studies have also shown that [2-14C]uracil and [14C]amino acids are taken up in their respective pools in the presence of captan or dieldrin.  相似文献   

20.
BACKGROUND: Captan is an important fungicide for controlling diseases in horticultural crops. Understanding its dissipation is important for estimating dietary risks and optimising pesticide application. Field experiments were conducted on apple leaves and fruit to investigate (1) the temporal variability of captan residues, (2) the contribution of several factors to the variability in residues and (3) the relationship between residues and climatic conditions. RESULTS: Initial captan deposits and subsequent residues on fruit and leaves were closer to a lognormal than to a normal distribution. The unit-to-unit variation contributed most to the observed variability in the initial deposit and subsequent residues. Variability due to orchards or trees or tree-zone interactions was also frequently important, but there was no discernable trend in the effects. The variability in residues did not appear to decrease over time. Canopy structure affected greatly the initial deposition but had little direct effect on subsequent captan loss. Fruit and leaves on the outside of the tree canopy received more deposit than those on the inside, but these differences gradually decreased over time. Captan loss resulted mainly from the first rainfall after an application. CONCLUSIONS: Captan loss is mainly due to rain, and the loss is negligible under dry conditions.  相似文献   

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