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.     

Degradation rates in soil of 1-benzyltriazoies and two triazole fungicides

The degradation rates in soil of 1-benzyltriazole together with six analogues having substituents in the phenyl ring and two commercial triazole fungicides, PP450 and triadimefon, were determined at 15°C and 20 % soil water content. The order of degradation rates of the benzyltriazoles was H > 4-OCH₃ > 4-F>4-Cl.4-≥tert-C₄H_g3,4-diCl>3-CF₃. Thus, in general, persistence was enhanced by electron-withdrawing substituents and by lipophilic groups that increased sorption by soil. Of the commercial fungicides, PP450 was degraded very slowly (half-life 578 days) while triadimefon was quickly converted (half-life 15 days) to the corresponding alcohol, triadimenol, which in turn was degraded very slowly. The effects of temperature and soil water content on rate of degradation were studied for 1-benzyltriazole and 1-(4-fluorobenzyl)triazole. The rate of degradation of 1-benzyltriazole was more sensitive to soil temperature and water content than was that of 1 -(4-fluorobenzyl)triazole. The influence of these results on the input data required by models which simulate persistence in field soil is discussed.     

Degradation of anilinopyrimidine fungicides photoinduced by iron(III)-polycarboxylate complexes

The photoinduced degradation of three anilinopyrimidine fungicides (cyprodinil, pyrimethanil and mepanipyrim) by Fe(III)-polycarboxylate complexes in aqueous solution was investigated. A photochemical redox reaction of Fe(III) complexes of oxalate and citrate occurs during irradiation (simulating sunlight) and is an important source of Fe(II) and a series of oxidants such as H2O2 and O radicals. The mechanism involves the formation of polycarboxylate radicals and/or carbon-centred radicals derived from decarboxylation, whereas the contribution of Fe(OH)2+ to O radical formation is negligible. The attack of O radicals on the fungicide molecules produces numerous photodegradation products, which were identified by means of LC-ES-MS and turned out to be mono- or dihydroxylated derivatives of the active ingredients, except for 2-amino-4,6-dimethylpyrimidine, which is only formed by pyrimethanil. The half-lives of the active ingredients, when submitted to irradiation in the presence of iron(III)-polycarboxylate complexes, were estimated to vary between 28 and 79 min (photodegradation rates in the same conditions: mepanipyrim > cyprodinil > pyrimethanil), and photodegradation is slower in citrate than in oxalate solutions. Photoproducts and their kinetics of formation are very similar for the three fungicides. The OH substitution involves the aromatic and the heterocyclic ring and the nitrogen bridge between the two rings, except for mepanipyrim when the hydroxylation also involves the propynylic side chain.     

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.     

新一代杀虫剂: 在叶部能稳定应用的dsRNA

核酸农药是一类可以特异性地结合靶标生物中特定基因转录的信使RNA的多核苷酸,通过靶标生物体内天然存在的RNA干扰系统沉默相应基因的表达,从而干扰靶标生物的正常生长及其对寄主植物的危害,最终达到保护植物的目的。相对于传统农药而言,核酸农药因其具有特异性较强、开发成本较低、安全绿色等优点正受到越来越多的关注。本文将围绕核酸农药的防治原理、优势特点及应用现状等方面进行综述,详细介绍以靶标基因为导向研制核酸农药的高效筛选方法及其研究进展,总结分析核酸农药未来发展方向和趋势,以期为核酸农药的进一步研发创制和推广应用提供参考。     

The strobilurin fungicides

Strobilurins are one of the most important classes of agricultural fungicide. Their invention was inspired by a group of fungicidally active natural products. The outstanding benefits they deliver are currently being utilised in a wide range of crops throughout the world. First launched in 1996, the strobilurins now include the world's biggest selling fungicide, azoxystrobin. By 2002 there will be six strobilurin active ingredients commercially available for agricultural use. This review describes in detail the properties of these active ingredients--their synthesis, biochemical mode of action, biokinetics, fungicidal activity, yield and quality benefits, resistance risk and human and environmental safety. It also describes the clear technical differences that exist between these active ingredients, particularly in the areas of fungicidal activity and biokinetics.     

甲氧基丙烯酸酯类杀菌剂在我国的登记用量分析

为探究嘧菌酯与硒代蛋氨酸复合暴露后对水体生物早期发育的影响,采用半静态试验法,测定了等毒性配比的嘧菌酯和硒代蛋氨酸二元混合体系复合暴露对水生模式生物斑马鱼胚胎及仔鱼的发育毒性及对相关酶活性的影响。结果表明：经不同质量浓度的嘧菌酯和硒代蛋氨酸(0.1 + 0.2、0.25 + 0.5、0.5 + 1.0和1.0 + 2.0 mg/L) (其中硒代蛋氨酸按硒元素的质量计,下同)复合暴露后,胚胎出现自主运动次数减少、孵化率降低、死亡率增加及心率下降现象,同时仔鱼体长受到显著抑制,且呈现明显的时间-剂量-效应关系;与对照组相比,在嘧菌酯和硒代蛋氨酸不同质量浓度(0.0005 + 0.001、0.005 + 0.01和0.05 + 0.1 mg/L)复合暴露下,斑马鱼仔鱼体内过氧化氢酶(CAT)活性显著降低,且高浓度复合暴露组(0.05 + 0.1 mg/L)的抑制作用最显著(P < 0.01),而对超氧化物歧化酶(SOD)活性则无显著影响;与对照组相比,高浓度复合暴露组显著抑制了线粒体呼吸链复合体Ⅲ的活性(P < 0.05),而其余浓度复合暴露组差异不显著。研究结果表明,经嘧菌酯与硒代蛋氨酸不同质量浓度复合暴露(0.1 + 0.2、0.25 + 0.5、0.5 + 1.0和1.0 + 2.0 mg/L)后,会对斑马鱼胚胎及仔鱼发育产生毒性效应,但在目前自然水体环境实际浓度水平下,除了抑制CAT活性外,尚不会产生其他毒性效应。以上研究结果可以为水体环境中嘧菌酯和硒代蛋氨酸浓度监测及复合暴露的生态风险评估提供数据支撑。     

基于RNA干扰的杀菌剂开发及其对化学杀菌剂的影响

RNA干扰(RNA interference, RNAi)是真核生物中高度保守的基因沉默现象,在医药与植物保护领域展现出广阔的应用潜力,相关产品已进入或即将进入医药与杀虫剂市场。近年来,科研工作者在基于RNAi技术的植物病原微生物的防控方面开展了大量研究,取得了进展,但仍无法实现基于RNAi防治植物病原真菌技术的商业化应用。本文概述了RNAi研究从1990年至今的发展历程,从细胞生物学、分子生物学角度提出了RNAi病害防控技术产品化瓶颈问题的新见解,同时讨论了基于RNAi的杀菌剂对传统化学杀菌剂的影响,可为RNAi杀菌剂的创制和应用提供参考。     

Environmental fungicides and triazole resistance in Aspergillus

Fungal diseases are problematic in both human health and agriculture. Treatment options are limited and resistance may emerge. The relatively recent recognition of triazole resistance in Aspergillus fumigatus has prompted questioning of the origin of resistance. While multiple mechanisms are described in clinical isolates from triazole‐treated patients, some de novo resistance is also recognised, especially attributable to TR₃₄/L98H. Such strains probably arose in the environment, and, indeed, multiple studies have now demonstrated TR₃₄/L98H triazole resistance strains of A. fumigatus from soil. Docking and other in vitro studies are consistent with environmental resistance induction through exposure to certain triazole fungicides, notably difenoconazole, propiconazole, epoxiconazole, bromuconazole and tebuconazole. This article addresses the potential implications of this issue for both human health and food security. © 2013 Society of Chemical Industry     

羧酸酰胺类(CAAs)杀菌剂研究进展

羧酸酰胺类(Carboxylic acid amides, CAAs) 化合物是一类对卵菌病害具有优异防治效果的新型杀菌剂。该类杀菌剂由3组化学结构各不相同的化合物组成,包括肉桂酰胺、缬氨酰胺氨基甲酸酯和扁桃酰胺类。由于这3类杀菌剂具有相似的杀菌活性且相互间存在正交互抗药性,国际杀菌剂抗药性行动委员会已于2005年底将这3类具有不同化学结构的杀菌剂归为羧酸酰胺类杀菌剂。对CAA类杀菌剂的化学结构特征、生物学活性、作用机制与抗药性的最新研究进展进行了综述。     

Persistence of resistance to fungicides in Sphaerotheca fuliginea

Isolates ofSphaerotheca fuliginea collected in 1981–1983 in cucumber glasshouses in the Netherlands were tested for their sensitivity to benzimidazole fungicides, dimethirimol, dinocap and pyrazophos.Resistance to dinocap was not observed, although this fungicide has been used for over 30 years. Resistance to benzimidazole fungicides and dimethirimol has been persistent since these fungicides were withdrawn for control of cucumber powdery mildew more than 10 years ago. Although pyrazophos has only been used incidentally after 1977, the level of resistance has not decreased.Factors possibly involved in the persistence of resistance and implications for disease control in practice are discussed.Samenvatting De gevoeligheid voor twee benzimidazool-fungiciden en dimethirimol, dinocap en pyrazofos werd getoetst vanSphaerotheca fuliginea isolaten die in 1981–1983 verzameld waren in komkommerkassen in Nederland. Resistentie tegen dinocap werd niet waargenomen, ofschoon dit fungicide al meer dan 30 jaar wordt gebruikt.De resistentie tegen benzimidazool-fungiciden en dimethirimol, die meer dan 10 jaar geleden werden teruggetrokken voor de bestrijding vanS. fuliginea, was persistent. Hoewel pyrazofos slechts incidenteel gebruikt is sinds 1977, is het resistentieniveau niet teruggelopen. Factoren die mogelijk betrokken zijn bij de persistentie van resistentie en de gevolgen voor de ziektebestrijding worden besproken.     

Inactivation of seed-treatment fungicides by Rhizobium

2-Methoxyethylmercury chloride (MEMC) applied to cowpea seeds with Rhizobium provided little or no control of seedling rot caused by Rhizoctonia solani; similar treatment, but without Rhizobium, gave >40% control of disease. Treating seeds with quintozene and then with Rhizobium rendered the fungicide completely ineffective against R. solani infections; disease control was >70% when seeds were treated with quintozene only, and >60% when seeds were coated first with Rhizobium and then with quintozene; treatment with quintozene+Rhizobium gave about 25% control. Simultaneous treatment with Rhizobium considerably reduced the efficacy of captafol, chloroneb, carbendazim and thiophanate-methyl. Disease control by carboxin, benomyl and thiabendazole remained unaltered in the presence of Rhizobium, but only thiabendazole gave good control. Seeds treated with MEMC and Rhizobium produced seedlings without root nodules; nodulation was also decreased by captafol and by carboxin but six other fungicides had no effect. The implications of Rhizobium-fungicides interactions are discussed in the context of fungicidal control of root diseases.     

Interactions of fungicides and leaf saprophytes

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.     

Review: The strobilurin fungicides

The original article to which this Correction refers was published in Pest Management Science 58 (7): 649–662 (2002).Copyright © 2004 Society of Chemical Industry     

After-effects of systemic fungicides in the control of soil-borne pathogens,and the interaction between systemic fungicides and growth regulators

After benomyl treatment of mustard seedlings, grown in Rhizoctonia-infested soil, root remainders left in the soil significantly suppressed Rhizoctonia infection in two successive, later ‘crops’ of mustard seedlings. This effect was even larger with the combination tomato — Verticillium albo-atrum.Antagonistic interactions between growth-regulating substances (chlormequat, dimas; chlorflurenol and ethephon) and benomyl were shown upon treatment of Phialophora cinerescens-infected carnations and of Verticillium albo-atrum-infected snapdragons. Application of growth regulators before fungicide treatment reduced the effect of the fungicide on Phialophora and Verticillium wilt. When applied after fungicide treatment, these growth substances did not interfere with benomyl activity.Also, observations on stem growth pointed to an interaction between growth regulators and benomyl. Growth substances, in themselves slightly inhibitory to growth, diminished the growth-promoting effect of benomyl.     

几种药剂对草莓炭疽病的效果

采用菌丝生长速率法测定了48%波尔多液可湿性粉剂、50%咪鲜胺可湿性粉剂、40%福美锌可湿性粉剂和70%代森联干悬浮剂4种药剂对草莓炭疽病菌的室内毒力。结果表明,4种药剂对菌丝生长的EC50的大小顺序为:50%咪鲜胺40%福美锌70%代森联48%波尔多液,50%咪鲜胺的EC50为6.24 mg/L。并选取毒力较好的50%咪鲜胺可湿性粉剂和40%福美锌可湿性粉剂进行了田间药效测定,48%波尔多液可湿性粉剂作为对照。试验发现:50%咪鲜胺可湿性粉剂在田间的效果最好,其800 mg/L处理在田间2次药后7 d的防效达到了80.26%,与对照药剂48%波尔多液可湿性粉剂间存在显著性差异。