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1.
Spray deposit assessments were made on the leaf surfaces in the top, middle and base zones of intensively grown apple trees sprayed by the conventional largevolume automatic method applying 2250 litres/ha and by fast overhead methods with nozzle booms applying 1125 litres/ha and with mist-blowing equipment applying 562 litres/ha. Qualitative assessment of spray cover, using a 0.05% suspension of Saturn Yellow fluorescent tracer showed that whereas the conventional method gave heavy cover on upper and lower surfaces in all zones, the two overhead methods gave heavier cover on the upper surfaces than on the lower and that an appreciable proportion of the lower surfaces especially in the base zone on trees sprayed by the overhead mist-blower had no fluorescent deposit. Quantitative assessments of copper spray deposits by colorimetric estimations separately on upper and lower surfaces agreed in general with the fluorescent tracer indications, especially the much greater deposits on the upper surfaces on the trees sprayed from overhead. Monitoring of captan spray deposits before and after each successive fungicide application through the season showed that in the three zones the residual and cumulative deposits from the conventional automatic applications were heavier and more uniform than those from the overhead methods which gave lighter deposits on the middle and base zones. In the intervals during which rain fell, most of the captan deposit levels from all methods of spraying were reduced by >70%, whereas during a rainless interval the reduction was 0–45%. The reduction of captan deposit levels during the rainy intervals was significantly greater on the trees sprayed from overhead than on the conventionally sprayed ones. There was a correlation between the percentage loss of captan and the rainfall in the intervals.  相似文献   

2.
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   

3.
Spray deposit assessments were made on the leaf surfaces in the top, middle and base zones of intensively grown dessert apple trees sprayed by a conventional high volume automatic mast method applying 2250 litres/ha, an experimental low and ulfralow volume tractor mist blower, applying 225 litres/ha at normal dilution, 45 litres/ha at five times normal concentration or 22.5 litres/ha at ten times normal concentration, and a modified proprietary hand-directed fan-disc sprayer applying 225 or 22.5 litres/ha. Fluorescent tracer assessments showed that the high volume method gave heavy cover on upper and lower surfaces of the leaves in all zones, the tractor mist method gave lighter but uniform cover and the fan-disc sprayer gave sparse cover on the upper surfaces at the top and on the lower surfaces at the base zone. The hand-directed low and ultralow volume methods, applying one-tenth of the amounts of copper fungicide/ha, gave deposit levels 5–30 % of those of the high volume method and the tractor mist applications gave 0.8–5.2%. The corresponding captan deposits from 5–6 applications were 12–50% and 10–20%: residual deposits from the ultralow volume applications of the concentrated captan were greater than the low volume applications of the same quantities in dilute form. In general, the order of pest and disease control obtained by the three methods was high volume automatic, fan-disc and experimental mist, and this was related to the order of deposit levels: the order of control by the three volume rates was 2250, 225 and 22.5 litres/ha, and this could be related to the degree of spray cover.  相似文献   

4.
A few specimens of ‘Ridomil 25 WP’, a commercial formulation of metalaxyl, showed high genetic activity on a heterozygous diploid strain of Aspergillus nidulans. This activity was due to an impurity which was identified by mass and n.m.r. spectroscopy as captafol. This and the related fungicides captan, dichlofluanid, and tolyfluanid greatly increased the yield of euploid colour segregants from the diploid strain. At low captafol concentrations, most of the induced segregants resulted from mitotic crossing over but chromosome non-disjunction or loss was also caused at high concentrations. Mitotic crossing over could be induced also by vapour-phase action of captafol and captan. The mechanism by which these phthalimides may exert their genetic effects is discussed.  相似文献   

5.
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   

6.
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   

7.
BACKGROUND: Captan is an important fungicide for controlling diseases in horticultural crops. Predicting its dissipation is important for estimating dietary risks and optimising pesticide application. Experiments were conducted to determine the relationship of captan loss on apple leaves with temperature, humidity and rainfall, and to investigate captan loss on fruit in dry conditions. RESULTS: There was large unit-to-unit variability in captan residues in spite of the controlled application. Temperature and humidity had negligible effects on captan loss. Captan loss is predominately due to washoff by rain, although a certain proportion of captan may bind to the plant surface tightly and hence may not be readily removed by rain. About 50% of captan can be washed off by as little as 1 mm of rain after an application, and the loss appeared not to relate to the amount of rain. Under dry conditions, daily loss of captan is estimated to be around 1% on both fruit and leaves, giving a half-life of ca 70 days. CONCLUSIONS: Captan loss on leaf and fruit surfaces is primarily due to rain washoff.  相似文献   

8.
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   

9.
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   

10.
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   

11.
The influence of surface of exposure of brassicas to insecticide sprays has been assessed in two experiments conducted in small plots where endosulfan, parathion, trichlorfon and pirimicarb were applied to a flowering brassica, broccoli (Brassica oleracea L. var italica Plenck) and to a leafy brassica (Brassica oleracea L. var. tronchuda Bailey). The differences of surface exposure resulted in much higher deposits and subsequent residue levels in broccoli. The results stress the need to evaluate residue data on groups of brassicas of different surfaces of exposure to pesticide spray when granting registration petitions for brassicas in general in order to establish pre-harvest intervals.  相似文献   

12.
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   

13.
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   

14.
Spray deposit patterns on simulated and live foliage of balsam fir and white birch were determined at different heights and at periphery and interior locations of the tree crown, following aerial and ground applications of fenitrothion formulations over a boreal forest near Searchmont, Ontario. Droplet size spectra and AI deposits were assessed at ground level with ‘Kromekote’ card/glass plate units. Aerial application was made with a Cessna 188 aircraft fitted with ‘Micronair’ AU3000 atomizers. For ground application, a ‘Soloport’ 423 backpack mistblower fitted with an extension tube and a diffuser nozzle at the tip was used. Deposit data on the ground samplers indicated significantly larger droplets and greater deposits from the aerial spray trial than from the mistblower treatment. However, foliar deposits at tree canopy level were only slightly higher in the former trial than in the latter. Analysis of spray deposits on simulated and live fir foliage showed definite gradients in deposit levels, decreasing from top to bottom crown, and from periphery to inner tree crown. In the birch tree crown, such gradients were not observed. The simulated leaves generally acted as better collectors of spray droplets than the natural leaves. The overall mean deposit values, expressed in ng cm?2, showed a wide variation, although there was generally a close relationship between the deposits on the simulated and natural surfaces.  相似文献   

15.
Results are reported for four experimental trials carried out against Botrytis cinerea on wine grapes in Piedmont (Northern Italy) during 1979 and 1980, using fungicides with different mechanisms of action, alternately or in mixture. Good effectiveness was obtained not only with the exclusive use of dicarboximide fungicides but also with alternated spray programmes, for example using benomyl or captafol or dichlofluanid for the first two sprays and the dicarboximides only for the last two sprays. It was possible to reduce the number of sprays with the dicarboximides to only one (at beginning of ripening), by, for example, alternating dichlofluanid, vinclozolin and benomyl. Good results were also obtained using half-rate mixtures of fungicides with different mechanisms of action, for example benomyl or dichlofluanid mixed with one of the dicarboximides. In this way the selection pressure exercised by the dicarboximides is decreased. Moreover, the cost of treatments is reduced owing to the lower price of benomyl, dichlofluanid and captafol and because these fungicides are effective not only against B. cinerea but also against powdery mildew (benomyl) or downy mildew (dichlofluanid and captafol).  相似文献   

16.
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   

17.
R.J. COOK 《EPPO Bulletin》1981,11(3):277-285
Field experiments with barley have generally shown a good relationship between disease and yield. However, in some experiments the yield response is greater than would be expected from the level of disease. In contrast, other trials have shown a reduction of yield following applications of tridemorph to spring barley. On winter wheat, trials in Germany have shown a poor relationship between disease incidence and yield following application of carbendazim or captafol at GS 30–31. About 10 96 of these responses were negative, although there was an average yield increase of 2–3 %. Similarly, in a series of trials in Britain an average yield increase of 3 % was not related to disease level. In these trials about 25 % of results showed no increase in yield. The carbendazim fungicides, and also certain others, have some cytokinin-like activity and it is possible that this is related to extended green leaf survival. Other interactions with host-cell chemistry can be envisaged. Fungicides also influence stability of the leaf microflora. By this effect they may favour diseases such as Typhula and Rhizoclonia, or else suppress secondary pathogens (Alternaria, Cladosporium) at the end of the season.  相似文献   

18.
BACKGROUND: Increasingly, Flemish greenhouse growers are using spray booms instead of spray guns to apply plant protection products. Although the advantages of spray booms are well known, growers still have many questions concerning nozzle choice and settings. Spray deposition using a vertical spray boom in tomatoes and strawberries was compared with reference spray equipment. Five different settings of nozzle type, size and pressure were tested with the spray boom. RESULTS: In general, the standard vertical spray boom performed better than the reference spray equipment in strawberries (spray gun) and in tomatoes (air‐assisted sprayer). Nozzle type and settings significantly affected spray deposition and crop penetration. Highest overall deposits in strawberries were achieved using air‐inclusion or extended‐range nozzles. In tomatoes, the extended‐range nozzles and the twin air‐inclusion nozzles performed best. Using smaller‐size extended‐range nozzles above the recommended pressure range resulted in lower deposits, especially inside the crop canopy. CONCLUSIONS: The use of a vertical spray boom is a promising technique for applying plant protection products in a safe and efficient way in tomatoes and strawberries, and nozzle choice and setting should be carefully considered. Copyright © 2009 Society of Chemical Industry  相似文献   

19.
Foliar uptake into eleven plant species, grown under controlled environment, has been determined for spray deposits of glyphosate, 2, 4-D and prochloraz applied as solutions in aqueous solvents in the presence and absence of an ethoxylated nonylphenol surfactant. Over 24 h, uptake of glyphosate did not exceed 6% of applied chemical into any species whereas uptake of 2, 4-D and prochloraz differed between species and was modified significantly by the addition of surfactant. Uptake of prochloraz was increased consistently by adding surfactant, but the response of 2, 4-D was variable. Increased uptake was attributed mainly to surfactant-enhanced wetting of the leaf surfaces. Uptake of prochloraz per unit wetted area increased in the presence of surfactant but that of 2, 4-D decreased. Uptake of either chemical did not correlate with the presence of specialised leaf surface structures, cuticular morphology or distribution of the chemicals within the dried deposits. The dried chemicals were distributed either uniformly or as annuli as a result of complex interactions between the active ingredient, surfactant and the leaf surfaces. Regression analysis indicated that the epicuticular wax and cuticular membrane were the major sinks for both 2, 4-D and prochloraz during the 24-h period.  相似文献   

20.
A detailed study has been conducted to evaluate the residues of endosulfan and its principal metabolite (alpha-endosulfan, beta-endosulfan and endosulfan sulfate) which may have accumulated in environmental samples due to regular aerial spray application of endosulfan on cashew leaf plantation for a period of 20 years. Three months after the last spray of endosulfan 350 g litre-1 EC at 300 ml acre-1 (equivalent to 105 g AI acre-1 = 42.5 g ha-1), a total of 93 samples of cow milk, fish, water, soil and dried cashew leaf were collected from a village in Kasargode District, Kerala, India, where endosulfan contamination was likely to have occurred. All the samples were analyzed for total residues of endosulfan (comprising alpha- and beta-endosulfan), endosulfan sulfate and also the potential hydrolysis product endosulfan diol, using gas chromatography with electron capture detection. The minimum detection limits of total endosulfan was 0.001 microgram g-1. Analysis of soil samples showed the deposition of total endosulfan residues in the range < 0.001-0.010 microgram g-1, and dried leaf samples showed residues of endosulfan in the range < 0.001-3.43 micrograms g-1 dry weight. In cow milk, fish and water, endosulfan residues could not be detected above the minimum detection limit. Endosulfan diol was not observed in any sample. The data obtained was confirmed by GC-MS-EI using selective ion monitoring (SIM) mode.  相似文献   

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