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The effects of temperature, humidity and rainfall on captan decline on apple leaves and fruit in controlled environment conditions 总被引:1,自引:0,他引:1
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
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Hughes EA Zalts A Ojeda JJ Flores AP Glass RC Montserrat JM 《Pest management science》2006,62(9):811-818
An analytical method has been developed that can be used to determine the potential dermal exposure (PDE) of workers to the pesticide captan in small-scale horticultural production units. The methodology is based on the whole body dosimetry technique, using a cotton coverall and cotton gloves as sampling media, with protective clothing worn beneath the cotton media to protect the operator. The quantitative determination of captan was done by gas chromatography-electron capture detector (GC-ECD), with the analytical method validated by measuring limits of detection and quantification, linear ranges, sample recovery and precision. Special emphasis is placed on factors that affected the stability of captan during chromatographic determination. The data generated for potential dermal exposure are presented separately for mixing/loading and application activities. These data are compared with values obtained with visible tracers using a similar field technique. Margin of safety (MOS) values are also calculated for the agricultural procedures studied. 相似文献
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Allowable levels for pesticide residues in foods,known as tolerances in the US and as maximum residue limits(MRLs) in much of the world,are widely yet inappropriately perceived as levels of safety concern. A novel approach to develop scientifically defensible levels of safety concern is presented and an example to determine acute and chronic pesticide food safety standard(PFSS) levels for the fungicide captan on strawberries is provided. Using this approach,the chronic PFSS level for captan on strawberries was determined to be 2 000 mg kg–1 and the acute PFSS level was determined to be 250 mg kg–1. Both levels are far above the existing tolerance and MRLs that commonly range from 3 to 20 mg kg–1,and provide evidence that captan residues detected at levels greater than the tolerance or MRLs are not of acute or chronic health concern even though they represent violative residues. The benefits of developing the PFSS approach to serve as a companion to existing tolerances/MRLs include a greater understanding concerning the health significance,if any,from exposure to violative pesticide residues. In addition,the PFSS approach can be universally applied to all potential pesticide residues on all food commodities,can be modified by specific jurisdictions to take into account differences in food consumption practices,and can help prioritize food residue monitoring by identifying the pesticide/commodity combinations of the greatest potential food safety concern and guiding development of field level analytical methods to detect pesticide residues on prioritized pesticide/commodity combinations. 相似文献
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Captan and fenitrothion dissipation in field-treated cauliflowers and effect of household processing
Fernández-Cruz ML Barreda M Villarroya M Peruga A Llanos S García-Baudín JM 《Pest management science》2006,62(7):637-645
Field trial studies have been performed with captan and fenitrothion on cauliflower to propose maximum residue limits and to study the dissipation of the pesticides. Residue levels have been determined at different times following good laboratory practice using gas chromatography with mass spectrometric detection. The behaviour of residue levels of these compounds after household processing has been analysed using gas chromatography with electron capture detection. Seven days after treatment, residue levels of captan could be detected, but not of fenitrothion. The half-lives of dissipation for captan and fenitrothion were calculated as 0.9 and 1.8 days respectively. Washing did not significantly affect the residual amounts of captan and fenitrothion observed in raw vegetables; however, after cooking, captan had degraded completely, whereas residue levels of fenitrothion were not modified significantly. 相似文献
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为筛选防治柑橘沙皮病的高效低毒药剂,连续两年进行了新型复配药剂50%克菌丹·啶氧菌酯水分散粒剂防治柑橘沙皮病的田间药效试验,对该药剂防治柑橘沙皮病的效果及安全性进行了评价。两年的试验结果表明:50%克菌丹·啶氧菌酯水分散粒剂有效成分用量625 mg/kg对柑橘沙皮病具有较好的防治效果,2018年药剂处理两次后对柑橘叶片和果实沙皮病的防治效果分别为78.46%和76.84%,2019年药剂处理两次后对柑橘叶片和果实沙皮病的防治效果分别为78.79%和75.59%,显著优于对照药剂80%克菌丹水分散粒剂800 mg/kg的处理,优于对照药剂22.5%啶氧菌酯悬浮剂150 mg/kg的处理。50%克菌丹·啶氧菌酯水分散粒剂对柑橘安全,值得应用于柑橘沙皮病防治的示范与推广。 相似文献
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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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P. H. Fourie F. Halleen 《European journal of plant pathology / European Foundation for Plant Pathology》2006,116(4):255-265
Wound protection during all stages of grapevine propagation is of utmost importance to prevent infection of propagation material by decline and dieback pathogens. In semi-commercial nursery trials, grapevine rootstock and scion cuttings were soaked in water (control), chemical or biological sanitation products prior to cold storage, prior to grafting (machine- or hand-grafting) and prior to planting in field nurseries. Natural infection levels in basal ends and graft unions of uprooted nursery grapevines were evaluated 8 months after planting. Total pathogen incidences in the water-treated control plants ranged from 30% in basal ends to 13.5% in graft unions. Phaeomoniella chlamydospora was the most commonly isolated pathogen, followed by Phaeoacremonium, Cylindrocarpon + Campylocarpon, Botryosphaeria and Phomopsis spp. Machine-grafted unions generally had lower pathogen incidences compared with hand-grafted graft unions. In general, repeated soak-treatments of propagation material in the tested products resulted in reduced pathogen incidences in nursery grapevines. However, products containing T. harzianum (Trichoflow-T), hydrogen peroxide (Bio-sterilizer) and 8-hydroxyquinoline sulphate (Chinosol) gave inconsistent results, whereas Bronocide (a blend of halogenated alcohols and water) proved to be a good sterilising agent, but reduced certifiable plant yield significantly. Benomyl (at 100 g/100 l), Sporekill (a patented didecyldimethylammonium chloride formulation at 150 ml/100 l) and captan (at 1000 ml/100 l) were consistently the best treatments as growth parameters were not negatively influenced and pathogen incidences in basal ends and graft unions of uprooted plants were reduced. 相似文献
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