噻菌灵、百菌清烟剂的分析方法

本文介绍选用5%XE-60为固定液的填充性，邻苯二甲酸二丁酯为内标物，用气相色谱法对5%噻菌灵，百菌清烟剂中的百菌清作定量分析；用高效液相色谱法，以甲醇 水 氢氧化铵（70 30 0.6)为流动相，C18反相柱定量测定噻菌灵，能有效地将杂质分离，是生产单位质量分析的可靠方法。     

Identification of potato scab-causing Streptomyces sp. occurring in strongly acidic soils in Saga Prefecture in Japan

Acid scab of potatoes occurs frequently in strongly acidic soils at pH 3.9–5.2. On the basis of the phylogenetic relationships derived from 16S rDNA sequences and physiological characteristics, we identified the organism causing this disease in potatoes grown in the Uwaba district of Saga Prefecture, Kyushu Island, southwest Japan, as Streptomyces acidiscabies. Another pathogen that occurred more frequently in weakly acidic to neutral soils, rather than strongly acidic soils, was identified as S. scabiei. Streptomyces acidiscabies tended to produce superficial lesions, while S. scabiei mostly produced raised and/or erumpent lesions.     

Uptake and distribution of thiabendazole by seed potatoes

The uptake of thiabendazole into potato seed tubers (cultivar King Edward) was determined by the method of application, more being taken up from solutions and suspensions than from dusts. Penetration and uptake were greatest with solutions at pH 3, and less at higher or lower pHs. The addition of inorganic salts (KCl, CaCl₂) had no effect. Treatment of tubers with weak solutions of mineral acid increased uptake of thiabendazole. There was little movement and no metabolism of the chemical when potatoes were stored for 3 months.     

Comparison of an in vitro and a damping-off assay to test soils for suppressiveness to Pythium aphanidermatum

Testing of soil samples in greenhouse assays for suppressiveness to soilborne plant pathogens requires a considerable investment in time and effort as well as large numbers of soil samples. To make it possible to process large numbers of samples efficiently, we compared an in vitro growth assay with a damping-off assay using Pythium aphanidermatum as the test organism on tomato seedlings. The in vitro test compares the radial growth or relative growth of the fungus in soil to that in autoclaved soil and reflects suppressiveness of soils to the pathogen. We used soils from a field experiment that had been farmed either organically or conventionally and into which a cover crop (oats and vetch in mixture) had been incorporated 0, 10, 21, and 35 days previously. We obtained a significant, positive correlation between damping-off severities of tomato seedlings in damping-off assays and both relative and radial growth in vitro. In addition, radial and relative growth of P. aphanidermatum in the in vitro assay were positively correlated with several carbon and nitrogen variables measured for soil and incorporated debris. We did not find differences between the two farming systems for either growth measures of P. aphanidermatum or disease severities on tomato at different stages of cover crop decomposition. The in vitro assay shows potential for use with any fungus that exhibits rapid saprophytic growth, and is most suitable for routine application in suppressiveness testing.     

Persistence of the fungicides thiabendazole, carbendazim and prochloraz-Mn in mushroom casing soil

The persistence of the fungicides thiabendazole, carbendazim and prochloraz-Mn in mushroom casing soil was determined following their application at rates commonly used in the UK mushroom industry. Following drench applications, the concentration of all active ingredients was always higher in the top half of the casing soil layer than in with the bottom half. When carbendazim and prochloraz-Mn were applied using half the recommended volume of water per unit area, there was a tendency for carbendazim concentrations to be even higher in the top half of the casing soil, compared with the standard treatment, while concentrations of prochloraz-Mn were similar, irrespective of the volume of water used. Carbendazim and prochloraz-Mn concentrations in the top half of the casing layer decreased to < or = 13 mg kg(-1) by day 28/29, following different applications, whereas the thiabendazole concentration was consistently high during the course of the crop, being < or = 83 mg kg(-1) at day 31. Fungicides that do not persist at high concentrations in mushroom casing soil for the duration of the crop may not give good control of mushroom pathogens, particularly if the fungicide concentration falls to a level which is close to the EC50 value.     

The comparative behaviour of simazine and terbacil in soils

Adsorption of simazine (2-chloro-4,6-bisethyl-amino-1,3,5-triazine) was 2.2–4 times greater than that of terbacil (5-chloro-6-methyl-3-t-butyl-uracil) in the same soils and adsorption of both herbicides was 2–4 times greater in the topsoils than subsoils. Adsorption was inversely correlated with herbicide movement in a thick-layer chromatography system. One year after application of 3 kg/ha to field plots, simazine residues were highest near the soil surface, whereas terbacil residues increased with soil depth in the sandy and sandy loam soils. Total residues recovered from the upper 25 cm of soils was 5% or less of the simazine originally applied, and 10% or less of the applied terbacil. In an oat seedling bio-assay, the GR₅₀ values were generally 1.5–3 times higher for simazine than for terbacil in the same soils.     

The occurrence of Piptocephalis in soils and its isolation

Samenvatting Piptocephalis species, onder andereP. cylindrospora Bainier, komen in Nederlandse kleigronden algemeen voor. Zij zijn zonder meer van het grondoppervlak af te enten na toevoeging aan grond van fijngemalen garnalenpantsers en zijn te isoleren door het uitplaten van grondverdunningen in wateragar met garnalenpantserpoeder.     

Accumulation patterns and fungicidal effect of carbendazim and thiabendazole in peanut plants after soil injection

Carbendazim and thiabendazole applied to the rhizosphere of peanut plants by injection into the soil at doses of 0.1, 0.5 and 2.5 g per 1 m row, accumulated in the leaves during the first week after treatment, the concentrations being related to the doses applied. Two weeks after treatment the concentrations of both fungicides dropped sharply. During the rest of the season, whilst the concentration of carbendazim in the high-dose treatment was 0.1 mg/kg fresh weight, the concentration of thiabendazole increased from 0.1 to 2.0 mg/kg and remained at this level until harvest. At the end of the growing season treated plants were less infected with Cercospora leaf spot (Cercospora per sonata) than the untreated control, thiabendazole affording better protection than carbendazim. Plants treated with the highest dose of thiabendazole were the only ones that did not wilt, even though infected. Laboratory studies of the adsorption of these fungicides on soil revealed that carbendazim is less adsorbed and also less persistent than thiabendazole.     

Lack of cross resistance to benomyl and thiabendazole in some strains of Aspergillus nidulans

Samenvatting Verworven resistentie inAspergillus nidulans tegen benomyl en thiabendazol bleek te berusten op één gen, gelocaliseerd op chromosoom VIII, op een afstand van 34 eenheden van ts-D 15 en 5 eenheden van orn-B 7. Hoewel kruisresistentie de regel is, blijkt dat sommige, mutanten tegen slechts één van beide fungiciden resistent zijn, en dat resistantie tegen thiabendazol zelfs gepaard kan gaan met extra gevoeligheid voor benomyl (Fig. 1 en 2).     

The determination of thiabendazole (2-(4-thiazolyl)-benzimidazole) in citrus fruit dips

Methods for analysing the strength of thiabendazole (TBZ) dipping fluids are described. The methods which require only the minimum laboratory facilities and can be used in citrus packing houses, are based upon (i) a titration method utilising the complex formed by TBZ with silver ions, for accurate work, and (ii) a refractive index method after concentration for rapid checking by packing house employees. These methods are compared with a spectrophotometric method.     

北京7种经济林吸滞PM_(2.5)特征及其价值评估

文中选取北京7个经济林树种,在仅考虑生态功能前提下,分析其作为园林绿化树种的吸滞PM_(2.5)特征,探讨叶表面形态特征对其影响,并利用合理指标评估其生态价值。结果表明:不同树种吸滞PM_(2.5)量介于0.089~0.258μg·cm-2,排序为:苹果>桃>枣>梨>核桃>杏>樱桃;吸滞PM_(2.5)量均在7、8月份较高,5月份较低;叶表面形态特征复杂,较为粗糙的叶片吸滞PM_(2.5)能力强;苹果吸滞PM_(2.5)量为0.83 kg·hm~(-2)·a-1,价值量约为67.47元·hm~(-2)·a-1。     

Characterization of triadimefon sorption in soils using supercritical fluid (SFE) and accelerated solvent (ASE) extraction techniques

Sorption–desorption of the fungicide triadimefon in field‐moist silt loam and sandy loam soils were determined using low‐density supercritical fluid extraction (SFE). The selectivity of SFE enables extraction of triadimefon from the soil water phase only, thus allowing calculation of sorption coefficients (K_d) at field‐moist or unsaturated conditions. Triadimefon sorption was influenced by factors such as soil moisture content and temperature; sorption increased with increased moisture content up to saturation, and decreased with increased temperature. For instance, K_d values for triadimefon on the silt loam and the sandy loam soils at 40 °C and 10% water content were 1.9 and 2.5 ml g⁻¹, respectively, and at 18% water content, 3.3 and 6.4 ml g⁻¹, respectively. Isosteric heats of sorption (ΔH_i) were −42 and −7 kJ mol⁻¹ for the silt loam and sandy loam soils, respectively. Sorption–desorption was also determined using an automated accelerated solvent extraction system (ASE), in which triadimefon was extracted from silt loam soil by 0.01 M CaCl₂. Using the ASE system, which is basically a fast alternative to the batch equilibration system, gave a similar ΔH_i value (−29 kJ mol⁻¹) for the silt loam soil (K_f = 27 µg^{1 − 1/n} ml^1/n g⁻¹). In order to predict transport of pesticides through the soil profile more accurately on the basis of these data, information is needed on sorption as a function of soil water content. © 2000 Society of Chemical Industry     

The degradation of simazine, linuron and propyzamide in different soils

Simazine, linuron and propyzamide were incubated in 18 different soils at 25°C and field capacity soil moisture content. The degradation of each herbicide followed first-order kinetics. The half-life of simazine varied from 20 to 44 days, that of linuron from 22 to 86 days and that of propyzamide from 10 to 32 days. The rate of linuron degradation was highly significantly correlated with soil organic matter content, clay content, soil respiration and the extent of herbicide adsorption by the soil. The rate of simazine degradation was significantly and negatively correlated with soil pH, but the rate of propyzamide degradation was not related with any of the soil factors examined.     

The breakdown of the triazine herbicide cyanazine in soils and maize

Radioisotope techniques have been used to study the breakdown products that are formed from the herbicide cyanazine ( BLADEX )^a, 2-chloro-4-(1-cyano-1-methylethyl-amino)-6-ethylamino-1,3,5-triazine, in soils and in maize grown in the soils under indoor conditions. In soils of different types cyanazine broke down mainly by conversion of the nitrile group to amide ( II ) and then to an acid ( III ) followed by hydrolysis of the ring chlorine to hydroxyl ( IV ). Dealkylation reactions occurred to only a limited extent in soils. In maize plants grown in treated soils the hydrolysis products, the amide ( II ) and the hydroxy acid ( IV ) were detected as well as appreciable quantities of products ( VI ) and ( VIII ) formed from these by loss of the N-ethyl group. In plants the hydroxy acids ( IV ) and ( VIII ) were present in the free form and there was also evidence for conjugates which were not identified but could be converted to these hydroxy acids, ( IV ) and ( VIII ), on treatment with acids. In these indoor studies the major residues appear to be the hydroxy acid ( IV ) in soils and ( IV ) and its dealkylated analogue ( VIII ) in plants grown in treated soils. These compounds are not herbicides and are of a low order of toxicity to mammals.     

Fate of vinclozolin,thiabendazole and dimethomorph during storage,handling and forcing of chicory

BACKGROUND: As part of ongoing research for a sustainable production of Belgian endives, the fate of three fungicides during storage, handling and forcing of witloof chicory roots was investigated. Storage roots are protected against Sclerotinia sp. Fuckel and Phoma exigua var. exigua Desm. by means of vinclozolin and thiabendazole respectively. During hydroponic forcing, the most imminent pathogen is Phytophthora cryptogea Pethybr. & Laff., which is controlled by the use of dimethomorph. RESULTS: Vinclozolin and thiabendazole concentrations on roots remained constant during storage at ?1 °C. Dermal exposure of the workers in hydroponics was exceeded. Vinclozolin and thiabendazole residues were not detected 2 weeks after hydroponic forcing; dimethomorph was still detected at harvest. At harvest, the vinclozolin concentration in the chicory heads was below the maximum residue limit, but the chicory roots contained residues much above the thiabendazole and dimethomorph maximum residue level. CONCLUSION: Vinclozolin and thiabendazole residues applied before storage are still present on the roots at the start of the forcing cycle. During the set‐up of chicory roots, preventive measures are recommended, as effects of repeated human exposure to low doses of applied fungicides cannot be excluded. Dimethomorph applied at the start of the hydroponic forcing is the only pesticide detected in the drainage water at harvest. The chicory heads were safe for human consumption. However, more attention should be paid to the residues of fungicides in the roots used for cattle feeding. Copyright © 2009 Society of Chemical Industry     

A new large scale soil DNA extraction procedure and real-time PCR assay for the detection of Sclerotium cepivorum in soil

A real-time PCR assay specific for Sclerotium cepivorum, the causal agent of white rot in onions, was developed for use with a new DNA extraction method capable of processing up to 1?kg of soil in weight. The assay was specific for S. cepivorum when tested against 24 isolates representative of 14 closely related species and other pathogens of onion. The assay was highly sensitive when used with soil DNA extracted using the new DNA extraction procedure. In three different field soils tested, a good relationship between cycle threshold (Ct) and number of sclerotia was observed (R2?=?0.89). Twenty-nine soil samples from onion and leek crops were obtained and the pathogen was detected in four samples. All four positive samples were associated with current or past outbreaks of white rot of onion. Additional assays were also used on the 29 field soil samples, Botrytis aclada and Rhizoctonia solani AG8 were also detected, in one soil sample each. Rhizoctonia solani AG2-1 was more widespread and was detected in eight different soil samples. The method is therefore suitable to quantify levels of S. cepivorum in soil samples, with the added advantage that the technique allows other soil pathogens of interest to be assayed from the same DNA sample. The bulk soil DNA extraction method described here has the potential to be used to detect soil-borne pests and pathogens for other crops in a wide range of soil types.     

蛹虫草TTC-脱氢酶测定方法的优化

TTC-脱氢酶还原法可用于检测和鉴别优良及退化蛹虫草菌株。这一方法的应用依赖测定参数的优化。本文优化了蛹虫草TTC-脱氢酶的测定方法,结果显示:测定蛹虫草TTC-脱氢酶活性时,培养6d的蛹虫草菌液先以生理盐水洗涤4次后配成0.15g/mL的待用菌液;反应缓冲液为Tris-HCl,最适pH值为8.4;最适反应温度为37℃、最适反应时间为3h。酶促反应完成后无需加终止剂,立即将样品放置冰上,4℃离心再以无菌水洗2次,用无水乙醇萃取便可测定吸光度得到脱氢酶活性。本文优化的蛹虫草TTC-脱氢酶活性检测方法具有测定结果稳定可靠、重现性好、准确度高、操作方便等优点。     

The adsorption and degradation of glyphosate in five Hawaiian sugarcane soils*

The rate of aerobic evolution of ¹⁴CO₂ from ¹⁴C-glyphosate labelled in the methylphosphonyl carbon, varied 100-fold within a group of five Hawaiian sugarcane soils. The rate depended inversely on the degree of soil binding, probably associated with the phosphonic acid moiety, and to a less certain extent on soil pH and soil organic matter. After an initial rapid degradation, the rate of ¹⁴CO₂ evolution in three soils reached a constant at 16–21 days which continued to the 60-day termination. The other two soils showed a continually decreasing rate throughout. Two soils released over 50% of the labelled carbon in 60 days, a third released 35%, while the remaining soils released 1.2 and 0.8% respectively. Labelled carbon in the soils after 60 days consisted of glyphosate and one metabolite, aminomethyl-phosphonic acid, with glyphosate predominating in high fixing soils. The ¹⁴C could be extracted almost completely with NaOH solution, and remained mainly in solution after acidification.     

超高效液相色谱-串联质谱法测定莲雾中多菌灵、噻菌灵和甲霜灵残留

建立了莲雾中多菌灵、噻菌灵和甲霜灵残留的超高效液相色谱-串联质谱(UPLC-MS/MS)的快速检测方法。样品直接用乙腈匀浆提取,过0.22μm滤膜后,在电喷雾正离子模式下以多反应监测(MRM)模式测定,基质匹配标准溶液外标法定量。结果表明:方法的线性范围为0.01~0.5μg/m L,决定系数(R2)0.99;在0.04、0.4和2 mg/kg 3个添加水平下,方法的平均回收率为75%~107%,相对标准偏差为2.0%~8.9%(n=5),定量限均为0.04 mg/kg。该方法样品前处理简单、快速,分析时间短,灵敏度、准确度和精密度均符合农药残留检测要求。