Enhanced Degradation of the Fungicide Vinclozolin: Isolation and Characterisation of a Responsible Organism

Enhanced degradation of the fungicide vinclozolin was stimulated by multiple successive applications to a soil without any history of previous pesticide input. A vinclozolin-degrading bacterium isolated from this soil was identified as a strain of Pseudomonas putida. This organism metabolised vinclozolin as a source of carbon, but it would neither grow with nor transform any other closely related dicarboximide fungicides nor the degradation product, 3,5-DCA. The degradation of vinclozolin by cultures of P. putida St-1 was investigated under various culture conditions; biodegradation was optimal at 23°C, pH 6·5 and inoculum densities of 10⁷ cells ml⁻¹ but cultures would grow from as little as 100 cells ml⁻¹. Amendments of the vinclozolin-degrading isolate to soil previously untreated with the fungicide caused rapid degradation of applied vinclozolin, whereas amendments of boiled cells, or viable cells grown in the absence of vinclozolin, produced no discernible effect on the rate of vinclozolin degradation.     

Persistence and biodegradation of vinclozolin in tropical rice soils

The persistence of vinclozolin in three tropical rice soils, widely varying in their physicochemical characteristics, was compared under both non-flooded and flooded conditions. Degradation of the fungicide was more rapid in all the soils under flooded conditions than under non-flooded conditions. Kinetic analysis indicated that the degradation of the fungicide followed a first-order reaction irrespective of soil or water regime. Soil acidity and salinity significantly affected the persistence of the fungicide under non-flooded conditions. The degradation of the dicarboxymide fungicide was enhanced following repeated applications to an alluvial soil under both water regimes, with the enhancement being more marked under flooded conditions. Faster degradation of vinclozolin in mineral salts medium inoculated with non-sterile suspension from retreated alluvial soil indicates the involvement of micro-organisms. 3,5-Dichloroaniline was detected as a metabolite in the degradation of the fungicide in both soil and mineral salts medium. © 1999 Society of Chemical Industry     

嘧菌酯在水和有机溶剂中的光化学降解

以500 W氙灯为光源,研究了嘧菌酯在水和有机溶剂中的光化学降解动态及其影响因素。结果表明:当质量浓度为5 mg/L时,嘧菌酯在纯水中光解的半衰期为5.8 h,在2~20 mg/L范围内,其光解速率随初始质量浓度的增大而降低;嘧菌酯在不同介质中的光解速率从大到小依次为乙腈水甲醇正己烷丙酮,其半衰期分别为4.8、5.8、11.5、12.1和23.5 h;硝酸盐对嘧菌酯在水中的光解具有光敏化作用,当NO-3质量浓度为1、2、10和20 mg/L时,其半衰期分别为5.5、5.1、4.5和3.9 h;在1~2 mg/L质量浓度下,NO-2对嘧菌酯在水中的光解具有光敏化作用,而在10~20 mg/L时则表现为光淬灭作用;Fe3+及表面活性剂十二烷基硫酸钠(SDS)对嘧菌酯在水中的光解具有光敏化作用,而腐殖酸和Fe2+则对其表现为光淬灭作用。研究结果可为嘧菌酯的科学合理使用及其环境风险评估提供参考。     

Degradation of the dicarboximide fungicides iprodione,vinclozolin and procymidone in Patumahoe clay loam soil,New Zealand

An enhanced rate of degradation of the dicarboximide fungicides iprodione and vinclozolin was induced in the laboratory in Patumahoe clay loam soil by adding three successive applications of fungicide. Enhanced degradation of the dicarboximide fungicide procymidone could not be induced. Following the first fungicide treatment, the time to 50% loss of iprodione was greater than 35 days; for vinclozolin the time to 50% loss was 22 days. The rate of degradation accelerated with successive applications until, after a third successive application of fungicide, the time to 50% loss of iprodione was only two days and none was detectable at seven days. For vinclozolin, after the third successive application of fungicide, 50% loss occurred after 35 days. By comparison, minimal loss of procymidone was detected after 35 days following each of two successive soil treatments. The induction of enhanced degradation of iprodione and vinclozolin in this soil in the laboratory may explain the observed loss of field control of onion white rot disease. Degradation of iprodione occurred in non-sterile soil but not in sterile soil, indicating that microbial involvement may be responsible for the degradation of iprodione and vinclozolin in soil.     

Characterization of a dicarboximide-fungicide-resistant laboratory isolate ofMonilinia laxa

Monilinia laxa, the incitant of blossom blight in stone fruits in Israel, is sensitive to 5μg/ml of the dicarboximide fungicides vinclozolin and iprodione in the growth medium. When a large number of spores, from an isolate never exposed to these fungicides, was seeded on a medium containing 15 μg/ml iprodione, spontaneous resistant mutants appeared at 10^-5 frequency. These mutants showed cross resistance to the dicarboximide fungicides vinclozolin, procymidone, l-(3,5-dichloro-phenyl)-3-propen(2)-pyrrolidin-2,5-dion (Co 4462), l-(3,5-dichlorophenyl)-3-methoxymethyl-pyrrolidin-2,5-dion (Co 6054), and to dicloran. Growth rate on fungicide-free medium was similar to that of the parental sensitive strain but sporulation was much reduced. Growth rate on media supplemented with dicarboximide fungicides decreased gradually with increasing fungicide concentrations. The resistance has been stable for more than one year in the absence of fungicides. Artificial inoculation of cherry, apricot and plum fruits previously treated with 500 μg/ml vinclozolin, iprodione, procymidone or Co 6054, with a resistant strain, resulted in brown rot; similar treatments provided full protection of the fruits against the sensitive strain.     

Enhanced degradation of iprodione and vinclozolin in soil

Residues of iprodione and vinclozolin were measured following repeated application of the fungicides to a sandy loam soil in the laboratory. There was a progressive increase in rates of degradation with successive treatments. With iprodione, for example, the times for 50% loss of the first and second applications were about 23 and 5 days respectively. When treated for the third time, less than 10% of the applied dose remained in the soil after just 2 days. Similar results were obtained with vinclozolin in the same soil, and with both compounds in a second soil. In a third soil, which had relatively low pH, degradation of both compounds occurred only slowly and the rate of degradation of a second application was the same as that of the first. Degradation rates in this soil were increased by addition of 100 g kg^?1 of a soil in which degradation occurred more readily, and they were markedly increased by addition of 100 g kg^?1 of a soil in which enhanced degradation had been previously induced. Residues of both fungicides were also measured following repeated application in the field. When iprodione was applied to previously untreated plots, about 3% of the initial dose remained in the soil after 77 days. When applied to plots treated once before, less than 1% remained after 18 days, and when applied to plots treated twice previously less than 1% remained after 10 days. Similar results were obtained with vinclozolin. Enhanced degradation of subsequent soil treatments was also observed following a sequence of low-dosage sprays in the field.     

Degradation of Diuron Photoinduced by Iron(III) in Aqueous Solution

The degradation of diuron photoinduced by iron(III) in aqueous solution has been investigated with different iron(III) species (monomeric species Fe(OH)²⁺, dimeric species Fe₂(OH)₂⁴⁺ and water-soluble oligomeric species) under monochromatic excitation at 365 nm and under sunlight. The rate of degradation depends on the concentration in Fe(OH)²⁺, the most reactive species in terms of ^•OH radical formation. The major photoproduct is 3-(3,4-dichlorophenyl)-1-formyl-1-methylurea which represents more than 60% of diuron disappearance. The mechanism only involves the attack by ^•OH radicals arising from iron(III) excited species. The half-lives of diuron when submitted to such a process in the environment were estimated to be 1–2 h and a few days according to the concentration of Fe(OH)²⁺ (respectively 70% and <10% of total iron(III) concentration).     

15%多菌灵·福美双悬浮种衣剂分析方法

本文介绍了采用液相色谱法,C18柱,以甲醇和水作为流动相,在230nm波长下,对多菌灵·福美双悬浮种衣剂中两种有效成分进行定量分析的方法。该方法的标准偏差分别为0.024和0.023;变异系数分别为0.30%和0.33%;平均回收率分别为99.7%和99.5%;线性相关系数分别为为0.9998和0.9994。     

特丁硫磷3％颗粒剂的高效液相色谱法测定

本文叙述了采用高效液相色谱外标法,以甲醇-水作为流动相,用C18柱和紫外检测器（240nm）,测定了特丁硫磷3％颗粒剂的含量。结果表明,方法的标准偏差为0．013;变异系数为0．43％;平均回收率为98．76％;线性相关系数为0．9933。     

3,5-二氯苯胺在水中的光解及水解特性

3,5-二氯苯胺 (3,5-DCA) 是二甲酰亚胺类杀菌剂 (DCFs) 在环境和植物中的主要降解代谢产物,比其母体化合物具有更强的毒性和持久性。本研究通过室内模拟试验,利用气相色谱-质谱联用仪 (GC-MS) 和高效液相色谱 (HPLC),研究了3,5-DCA的光解和水解特性。结果表明:初始质量浓度为5 mg/L的3,5-DCA在氙灯和紫外灯下光解的半衰期分别为49.5 和11.6 min;在中性、酸性和碱性条件下光解的半衰期分别为9.9、168和10.7 min;在甲醇、乙腈、正己烷中光解的半衰期分别为4.10、2.69和0.58 h。进一步研究发现,3,5-DCA在正己烷中的光解产物为单脱氯产物。3,5-DCA在中性、酸性和碱性条件下的水解半衰期分别为40.8、77.0和86.6 d。不同浓度的表面活性剂十二烷基磺酸钠 (SDS) 和十六烷基三甲基溴化铵 (CTAB) 溶液均可抑制3,5-DCA的水解,其中CTAB的抑制效果强于SDS。研究结果有助于更全面地了解二甲酰亚胺类杀菌剂的环境归趋,可为其合理使用及环境安全性评价提供数据支持。     

Field effectiveness and biodegradation of cyclic imides in lettuce field soils

When 42 field trials, carried out from 1975 to 1989 in the Perpignan region (France) for control of lettuce drop caused by Sclerotinia minor, were compared, a decrease in the field effectiveness of cyclic imides was perceptible, beginning approximately in 1985. Moreover, in 15 out of 46 commercial lettuce fields surveyed in 1988 and 1989, the effectiveness of iprodione was less than 80%, the level of acceptability for the growers. In these fields, fungicide degradation, estimated by 3,5-dichloroaniline formation, was faster than in soils in which S. minor was adequately controlled. Statistical analyses showed that the iprodione degradation index was strongly linked to the history of fungicide treatment and was weakly correlated to soil pH or clay content. All the fields characterized by low iprodione effectiveness were associated with high levels of fungicide treatment and high degradation index. Moreover, we observed that soil from a field which had received iprodione for more than ten years did not degrade vinclozolin quickly, while soil from another part of the same field which had been treated with vinclozolin for eight years degraded vinclozolin faster than iprodione.     

Degradation of dicarboximidic fungicides in wine. Part II: Isolation and identification of the major breakdown products of chlozolinate,vinclozolin and procymidone

The main degradation products formed from the dicarboximidic fungicides chlozolinate, vinclozolin and procymidone in wine have been isolated and identified using spectroscopic and chromatographic methods. The fungicides were added to wine after fermentation. Chlozolinate underwent a rapid hydrolytic loss of the ethoxy-carbonyl substituent, to give an oxazolidine that underwent hydrolytic cleavage to give 3′,5′-dichloro-2-hydroxypropanilide. The oxazolidine ring of vinclozolin underwent a similar hydrolysis to give the corresponding anilide 3′,5′-dichloro-2-hydroxy-2-methylbut-3-enanilide. Both these anilides were stable in wine for 150 days. A different degradation behaviour was observed with procymidone and led to the formation of 3,5-dichloroaniline (3,5-DCA), which, in turn, broke down but the derivatives could not be isolated. After consideration of the different behaviours of the fungicides on degradation in wine and in aqueous ethanol at pH4, together with their kinetic data, breakdown pathways are proposed.     

Optimization of hydroponic bioassay for herbicide tepraloxydim by using water free from chlorine

Initial attempts to develop a hydroponic bioassay test for tepraloxydim failed due to lack of repeatability. Investigation of the fate of tepraloxydim in test media revealed that small residues of chlorine and chloramines present on distilled water cause fast degradation of the herbicide. Half‐life of tepraloxydim in the presence of a chlorine excess was determined to be DT₅₀ < 5 s. Reaction with chloramines was slower (DT₅₀ = 4.5 h). Finally, when this factor was eliminated by using water completely free of chlorine, the main process that took place was the isomerization of the oxime group (E vs. Z). However, the overall degradation was slow (DT₅₀ = 17 days) and the hydroponic bioassay was optimized in the absence of chlorine.     

Differences in light stability of some carboxylic acid anilide fungicides in relation to their applicability for seed and foliar treatment

Irradiation of carboxin, furcarbanil, pyracarbolid, cyclafuramid, benodanil, mebenil and oxycarboxin by u.v. light (254 nm) for 4 h resulted in 97, 64, 58, 50, 20, 18 and 15% inactivation, respectively. Photoinactivation of the different compounds in aqueous solution or in the solid state was much slower in sunlight than in u.v. light and stability increased in the following order: carboxin < furcarbanil ≤ cyclafuramid ≤ pyracarbolid < mebenil ≤ benodanil < oxycarboxin. The residues of carboxin and furcarbanil on the leaf surface of bean plants were almost completely inactivated after 40 h exposure to sunlight; cyclafuramid lost 85% of its activity. The toxicity of leaf deposits of pyracarbolid, mebenil, benodanil and oxycarboxin decreased by 83, 53, 50 and 41%, respectively after 80 h in sunlight. The compounds with low photostability (e.g. carboxin, furcarbanil and cyclafuramid) are recommended mainly for controlling seed- and soil-borne fungi; pyracarbolid, mebenil, oxycarboxin and benodanil, which proved to be more photostable, appear to be useful fungicides to control rust diseases. Among several photochemical decomposition products of carboxin detected, the sulphoxide and sulphone were identified.     

五种杀虫剂对蜜蜂的经口毒性及风险评价

分别采用"小烧杯法"和"饲喂管法" 检测了50%虫螨腈水分散粒剂(WG)、1%甲氨基阿维菌素苯甲酸盐乳油(EC)、80%氟虫腈水分散粒剂(WG)、50 g/L氟虫腈悬浮剂(SC)、10%阿维菌素·哒螨灵乳油(EC)5种杀虫剂对蜜蜂工蜂的经口毒性。其中, "小烧杯法"测得的48 h LC50值分别为21.3、0.490、0.112、0.075 7、0.488 mg/L, "饲喂管法"测得的48 h LC50值分别为134、0.730、1.33、0.668、1.54 mg/L。就这5种杀虫剂而言,"饲喂管法"测得的48 h LC50值均不同程度高于"小烧杯法"。以摄入量计,则"饲喂管法"测得的48 h LD50值分别为1.34、0.007 30、0.013 3、0.005 37、0.015 4 μg/蜂。按毒性等级标准划分, 50%虫螨腈WG对蜜蜂具有中等毒性,1%甲氨基阿维菌素苯甲酸盐EC、10%阿维菌素·哒螨灵EC、80%氟虫腈WG和50 g/L氟虫腈SC对蜜蜂为剧毒。如果采用危害商值(Hazard Quotient,HQ)衡量药剂的风险性,则上述5种杀虫剂对蜜蜂的HQ值分别为84.0、205、3 247、3 609、8 939,表明它们对蜜蜂均具有潜在风险。同时还就两种检测方法的优缺点和适用范围进行了比较。     

柱前衍生-高效液相色谱法检测水中王铜残留的研究

建立了一种柱前衍生-高效液相色谱检测水中王铜（碱式氯化铜,copper oxychloride）的方法,并应用于不同水样中王铜残留量的测定。样品在酸性条件下经二乙基二硫代氨基甲酸钠（DDTC-Na）柱前衍生,使用C18反相色谱柱,以甲醇-水为流动相等度洗脱,在305 nm波长下进行检测。结果表明:在0.06~2 mg/L范围内,王铜的质量浓度与对应的峰面积间线性关系良好,方法的检出限（LOD）为0.02 mg/L,定量限（LOQ）为0.06 mg/L;在0.06、0.2和1 mg/L添加水平下,王铜在3种水样中的平均回收率在85%~108%之间,相对标准偏差（RSD）在2.2%~14%之间,3种水样对王铜的检测均不产生干扰。该方法准确、可靠,操作简便,可应用于快速检测水中王铜的残留量。     

Further observations on the enhanced degradation of iprodione and vinclozolin in soil

The effects of soil pH on rates of degradation of iprodione and vinclozolin were measured in a silty clay loam soil. Little degradation of either fungicide occurred at pH 4.3 or 5.0, and degradation at pH 5.7 was slower than at pH 6.5. In both of the higher-pH soils, the rate of loss of a second application of either fungicide was faster than that of the first, and a third application degraded even more quickly. In soil with pH 6.5, for example, the times for 50% degradation of iprodione following the first, second and third applications were about 30, 12 and 4 days, and for vinclozolin were 30, 22 and 7 days respectively. Iprodione degraded very rapidly in a sandy loam that had been treated three times previously with this fungicide and also degraded rapidly in the same soil pretreated three times with vinclozolin. Vinclozolin degraded rapidly in the vinclozolin pre-treated soil, but its rate of loss in the iprodione pre-treated soil was only slightly faster than in the previously untreated control. Studies of iprodione degradation in 33 soils from commercial fields demonstrated a clear trend towards faster rates of loss in soils with an extensive history of iprodione use. The time for 90% loss from previously untreated soils varied from 22 to 93 days. It varied from 16 to 28 days in soils treated once previously and from 5.2 to 23 days in soils treated twice previously. In soils that had received three or more previous doses, the time to 90% degradation varied from 3.8 to 15 days.     

三氯异氰尿酸的液相色谱分析

本文介绍了使用反相高效液相色谱，C18柱，以甲醇和冰乙酸水溶液为流动相，紫外检测器，对三氯异氰尿酸制剂进行定量分析的方法。该方法的标准偏差为0.03，变异系数为0．06％，线性相关系效为0．9994，平均回收率为100.3％。     

Sensitivity of populations ofBotrytis cinerea to triazoles,benomyl and vinclozolin

Sensitivity of field isolates (121) ofBotrytis cinerea from France (1992), Germany (1979–1992), Israel (1990) and the Netherlands (1970–1989) to the triazoles tebuconazole and triadimenol, the benzimidazole benomyl and the dicarboximide vinclozolin were tested in radial growth experiments. Resistance to benomyl (in 21 to 100% of isolates tested) and vinclozolin (in 25 to 71% of isolates tested) was common in most countries. EC₅₀s (concentrations of fungicides inhibiting radial mycelial growth ofB. cinerea on B5-agar by 50%) for tebuconazole and triadimenol ranged between 0.01–1.64 and 0.4–32.6g ml^–1, respectively, and were log-normally distributed. The variation factor (ratio between EC₅₀s of the least and most sensitive isolate tested) amounts 164 and 82 for tebuconazole and triadimenol, respectively. These values are comparable to those for azole fungicides applied in control of other pathogens. Hence, variation in sensitivity to triazoles can probably not explain limited field performance of triazoles towardsB. cinerea. Isolates from south west Germany (1992) were significantly less sensitive to tebuconazole than isolates collected earlier in Germany, Israel and the Netherlands. Such less sensitive populations may contribute to the limited field performance of DMI fungicides towardsB. cinerea. The sensitivity of isolates from south west Germany to tebuconazole was similar to that of DMI-resistant mutants generated in the laboratory. These mutants displayed stable resistance with Q-values (ratio between EC₅₀ of resistant mutant and wild type isolate) between 5 and 20. Sensitivity of field isolates and laboratory mutants to tebuconazole and triadimenol was correlated.     

Mechanisms of dicarboximide ring opening in aqueous media: Procymidone,vinclozolin and chlozolinate

The hydrolysis kinetics of the dicarboximide fungicides procymidone, vinclozolin and chlozolinate in neutral and alkaline solutions of pH 60 to 13·7 at 25°C have been determined conjointly by ultraviolet spectrophotometry and by high performance liquid chromatography. Under alkaline conditions, the fungicides undergo attack by the hydroxide ion on a specific carbonyl group and the rate of hydrolysis increases proportionally to the hydroxide ion concentration. Procymidone gives quantitatively and irreversibly 2-(3,5-dichlorophenylcarba-moyl)-l,2-dimethylcyclopropanecarboxylate. The reaction is not subject to general base catalysis and experimental data are in agreement with a rate-determining attack by the hydroxide ion. After a rapid hydrolytic loss of the ethoxycarbonyl substituent from chlozolinate, the dicarboximide ring cleavage of the two other fungicides leads, by mechanisms which differ with respect to the type of base catalysis and the rate-determining step, to the corresponding anilides, producing as intermediates the carbamic acids, which undergo loss of carbon dioxide. The hydrolysis of vinclozolin and chlozolinate yields, respectively, N-(3,5-dichloro-phenyt)-2-hydroxy-2-methylbut-3-enanilide and N-(3,5-dichlorophenyl)-2-hydroxy-propanilide.