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.     

Affinity and mobility of fungicidal dialkyl dithiolanylidenemalonates in rice plants

The affinity of certain fungicide analogs to rice plant varied progressively, showing a linear decrease with decreasing length of, or branching of, the alkyl chains, and correlated well with the hydrophobic parameter, log P. The more hydrophobic the compound was, the higher was the affinity to rice plant. Compound mobility in rice plant also varied regularly. The resulting relationship between hydrophobicity and mobility of these fungicide analogs suggested that the situation in rice plant is quite analogous to rice-plant column chromatography, by which the affinity to rice plant was determined. The major factor preventing movement within the plants seems to be interaction with sites in the rice plant leading to partition or binding and the resulting loss from the transpiration stream.     

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。     

Degradation and adsorption of carbendazim and 2-aminobenzimidazole in soil

Increasing adsorption of [¹⁴C]-labelled carbendazim in soil took place within a few weeks of incubation and was greatest in soil with a high organic matter content. Carbendazim was slowly decomposed in soil, mainly by soil microorganisms. After 250 days of incubation in two unsterilised soils, 13 and 5% respectively of added [¹⁴C]-carbendazim was recovered compared with 70 and 50% respectively from sterile soils; 4–8% of added carbendazim was recovered as 2-aminobenzimidazole (2-AB) from both unsterilised and sterile soil. After 270 days' incubation, 33 and 9% of ¹⁴C was recovered as ¹⁴CO₂ from soil supplied with [¹⁴C]-carbendazim (20 and 100 mg/kg) respectively. Degradation started more rapidly when carbendazim was added to soil preincubated with the fungicide but the degradation rate was very low in all cases, indicating that the compound is a poor microbial energy source and that the degradation is a co-metabolic process. 2-AB was found as a degradation product although it appeared to be unstable in soil, decomposing rapidly after a lag period of about 3 weeks; small amounts remained in the soil for several months, however, presumably adsorbed on soil particles.     

多菌灵在杭白菊及其土壤中的残留消解动态

通过田间植株直接施药-定期采样提取-高效液相色谱分析的方法,研究了多菌灵在杭白菊胎菊、菊花及土壤中的残留消解动态,测定了多菌灵在杭白菊胎菊和菊花中的最终残留量,并在室内探讨了不同温度对干胎菊和干菊花中多菌灵消解的影响。结果表明:在0.675和1.00 kg/hm2 2个施药剂量下,多菌灵在杭白菊土壤、胎菊和菊花中的消解半衰期分别为7.98~8.34 d、3.90~4.05 d和3.31~3.45 d;不同温度下,干胎菊和干菊花中多菌灵的半衰期存在显著性差异(P2的剂量喷雾施用2次,第2次施药后21 d时多菌灵在干胎菊和干菊花中的残留量分别为0.182~0.294 mg/kg和0.371~0.381 mg/kg,远低于我国制定的多菌灵在怀菊中的最大残留限量标准(5 mg/kg)。     

四粒红花生物料特性试验与测定

以新疆中西部地区林果套种模式下的‘四粒红’花生为研究对象,在田间调研的基础上,应用微控电子万能试验机、MS-70红外线水分测定仪和ZRQF-F30J手持式数显热球风速计等试验设备,研究花生在挖掘铺放晾晒过程中含水率,秧柄节点、果柄节点与果柄拉伸力,花生荚果破碎力以及花生荚果、茎秆和叶片在不同含水率下的风力悬浮速度范围。本研究初步确定了最佳的收获时间为花生晾晒后5～7 d,此时花生秧蔓、果柄、花生荚果的含水率分别为34.5%降至24.0%、22.0%降至16.0%、14.0%降至9.0%,果柄、秧柄节点、果柄节点的拉伸力分别为14.95～15.10、12.50～12.90、8.45～8.60 N,花生荚果侧面、荚果正面、荚果立面破碎力分别为45.0 N降至41.0 N、86.5 N降至70.3 N、42.0 N降至36.1 N,花生荚果、茎秆、花生叶片的风力悬浮速度分别为5.82～6.97、2.43～2.77、1.97～2.44 m·s^-1,研究结果为后续花生收获机械设计、研制提供参考。     

花生植株、籽粒及田间土壤氟磺胺草醚残留分析方法研究

在前人研究基础上, 确立了花生植株以甲醇、乙二胺-N-丙基硅烷（PSA）和石墨化炭黑（GCB）为基质分散萃取材料, 花生籽粒和田间土壤分别以酸化甲醇和乙腈为分散萃取溶剂, 以PSA为基质净化材料的3类氟磺胺草醚残留样品前处理程序, 建立并优化了花生籽粒、花生植株和田间土壤氟磺胺草醚残留高效液相色谱检测方法。结果显示, 氟磺胺草醚在0.05~10.0 mg/L质量浓度范围内与对应色谱峰积分面积线性响应良好, 回归方程为 y =2.562 8x -0. 006 8（r 2=0.999 8）。在0.05 ~0.5 mg/kg氟磺胺草醚添加范围内, 花生籽粒、植株和田间土壤中的平均回收率为85.6%~113.5%, 相对标准偏差为1.5%~9.7%。花生植株、籽粒和田间土壤中氟磺胺草醚的检出限分别为0.024、0.029和0.031 mg/kg。基质效应试验结果表明, 该样品前处理方法获得的分析样品基质效应不明显, 表明该残留样本前处理方法和样品检测方法简便、高效、经济、可靠, 可满足氟磺胺草醚在花生植株、籽粒及田间土壤中残留的定量检测要求。     

Concentration-time relationships for methyl isothiocyanate in soil after injection of metham-sodium

Soil fumigation with metham-sodium in the field was studied in detail by characterising soil and climatic conditions, and by measuring concentrations of methyl isothiocyanate. The effectiveness of two dosages in two contrasting soil profiles was compared on the basis of computed concentration-time products for methyl isothiocyanate in the water phase. Under wet conditions, the vapour diffusion of methyl isothiocyanate was very slow and resulted in an irregular distribution in the soil. Showers further decreased effectiveness in the upper part of the soil. A dried top layer was unfavourable for the concentration-time product near to the surface. Diffusion of methyl isothiocyanate to depths greater than about 30 cm was very slow.     

Foliar application of benzovindiflupyr shows non‐fungicidal effects in wheat plants

BACKGROUND

The fungicide benzovindiflupyr belongs to the class of succinate dehydrogenase inhibitors (SDHIs). Certain SDHIs have shown plant physiological effects, so‐called secondary effects, that appeared to be related to the plant water status. Therefore, the effect of benzovindiflupyr on transpiration of leaves and whole wheat plants was studied under controlled conditions. Furthermore, wheat yield trials under controlled and natural drought stress in the field were conducted.

RESULTS

Transpiration of detached wheat leaves was reduced by benzovindiflupyr in a dose‐dependent manner. Similarly, whole‐plant transpiration decreased for several days following application of this fungicide. In 16 field trials under drought stress conditions that were classified as disease‐free, treatment of wheat plants at the flag leaf stage or at heading with benzovindiflupyr showed a grain yield increase (+5.2%; P ≤ 0.01) that was partially attributed to an increased thousand‐grain weight.

CONCLUSIONS

Water saving during pre‐anthesis as a result of benzovindiflupyr application may be associated with better seed setting and filling under dry field conditions in wheat. The results of this research provide new insights into secondary effects of SDHIs that lead directly to yield improvements. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

多菌灵对新疆灰漠土细菌群落多样性的影响

本研究旨在探明不同浓度多菌灵处理对土壤细菌群落多样性的影响,从而为多菌灵的合理使用和减少环境污染提供科学依据。采用PCR-DGGE方法,研究了新疆灰漠土上不同浓度多菌灵处理(0、5、10、20、50 mg/kg和100 mg/kg)细菌群落结构的变化。结果表明:试验条件下,在土壤细菌群落多样性分析中,Shannon-Wiener指数和丰富度在多菌灵施用14 d时随着多菌灵浓度的增加有所增加,在28 d和42 d时则随着多菌灵浓度的增加而降低,Shannon-Wiener指数降低的幅度分别为4.05%~29.48%和6.13%~16.86%,丰富度降低的幅度分别为9.01%~63.64%和22.22%~38.89%;多菌灵处理对细菌均匀度和Simpson指数的影响不大。综合分析认为,施用多菌灵不仅影响了土壤细菌群落的种类和结构组成,还改变了土壤细菌的种群数量和结构多样性,导致其多样性降低。     

Metabolism of bifenox in soil and plants

The herbicide, methyl 5-(2,4-dichlorophenoxy)-2-nitrobenzoate (bifenox), had a half-life of 3 to 7 days after preemergence application to a greenhouse soil mix. Metabolites identified included: 5-(2,4-dichlorophenoxy)-2-nitrobenzoic acid, 2,4-dichlorophenyl 4-nitrophenyl ether (nitrofen), and 5-(2,4-dichlorophenoxy)anthranilic acid over a 313-day sampling period. Comparison of the total ¹⁴C in the soil to that extractable by methanol showed an increase in the proportion of bound material. The major metabolite eluted from a Frederick clay loam soil column was identified as the acid of bifenox and its mobility was associated with the short half-life of bifenox in soil. In vitro studies with shoot-tissue macerates showed that bifenox was not degraded by corn (Zea mays L.) or soybeans (Glycine max (L.) Merr.) and was degraded to less than 1% by velvetleaf (Abutilon theophrasti Medic.).     

Fate of carbendazim in rice tissues after seed or foliage treatments

Carbendazim was quantified employing reversed-phase high-performance liquid chromatography in rice coleoptiles, radicles and shoot portions of seedlings of different ages grown from seeds treated with the fungicide, and in shoot portions of adult plants at different times after foliar treatment with the fungicide. The highest levels of carbendazim were detected in the coleoptiles four days after germination of seeds and the radicals contained the lowest concentrations. Carbendazim residues declined with time in the shoot portions of seedlings and of adult plants. However, the levels of carbendazim detected in the shoot tissues of 21-day-old seedlings grown from treated seeds [recommended dose of 10 mg a.i. 10g^?1 seeds] and in adult plants 35 days after treatment (recommended dose of 0.25 g a.i. litre^?1 spray fluid) correspond to the reported lasting ability of the fungicide in terms of protection against blast of rice.     

Influence of methyl bromide soil fumigation method on fungicidal efficacy and bromide residues

Highest inorganic bromine residues (30 ppm) were found when soil was fumigated with liquid methyl bromide (MB) introduced by conventional means into evaporating dishes. With preheated (vaporized) MB or injection of MB/chloropicrin (CP) mixtures, bromide concentrations were reduced by 50%. They were uniform throughout the soil (0 to 60 cm) except after MB/CP injection, when larger residues were found in the 30-60 cm layer. Leaching with 2000 m^p3/ha (20 cm) of water always reduced bromide content to 7.5 and 10 ppm at the 0-30 and 30-60 cm depth, respectively. Organic amendments to soils substantially increased bromide levels up to 118 ppm, most of which was found in the upper soil layers; two teachings with 2000 m^p3 /ha water were required to return the soils to their normal state.Sclerotium rolfsii andFusarium oxysporum f. sp.dianthi cultures buried in soil were eliminated from the upper 30 cm with MB applied either conventionally or preheated. At 50 cm, 500 kg/ha of the preheated gas was superior to 1000 kg/ha of the cold gas. All MB fumigations suppressed carnation flower yields compared with CP alone but were superior to no treatment. After leaching, MB-fumigated soils yielded the highest number of flowers.     

Dynamics of uptake,translocation, and disappearance of thiabendazole and methyl-2-benzimidazolecarbamate in pepper and tomato plants

The dynamics of the uptake, translocation, and disappearance of thiabendazole (TBZ) and methyl-2-benzimidazolecarbamate (MBC), the fungicidal breakdown product of benomyl, were studied in tomato and pepper plants grown on nutrient solutions containing 0.5 ppm TBZ and 2.5 ppm MBC. Chemical analysis of pepper plants showed that the fungicides accumulated in the leaves only, where concentrations of 20 ppm TBZ and 60 ppm MBC were recorded. Thiabendazole was completely removed from pepper plants by acetone extraction, whereas MBC was only partially removed by acetone and the rest was weakly bound to the tissue and released by either methanolic HCl extraction or acid hydrolysis. The rate of disappearance of TBZ from pepper leaves was three to four times faster than that of MBC. Balance studies in tomatoes have shown an average disappearance rate of 13.5% per 10 days for MBC. 2-Aminobenzimidazole, the degradation product of MBC, was always detected but its concentration did not exceed 2% of that of the parent compound.     

不同轮作模式对花生病虫害及产量的影响

为探明水旱轮作模式对花生土传病虫害及其产量的影响,设水旱轮作不施药、水旱轮作减施药、旱旱轮作常规施药和旱旱轮作不施药(CK)4种处理,于2014—2016年对花生果腐病、白绢病和蛴螬虫害的发生情况进行调查,并对花生产量及其构成因素进行考种分析。结果表明,水旱轮作不施药处理的花生果腐病病情指数和发病率分别较CK显著降低90.40%和96.55%,防控效果达96.34%;水旱轮作减施药处理对花生果腐病的防控效果为81.49%;旱旱轮作常规施药处理对花生果腐病无防控效果。水旱轮作和旱旱轮作常规施药处理对白绢病均无防控效果。水旱轮作不施药、水旱轮作减施药和旱旱轮作常规施药处理对蛴螬的防控效果分别为63.80%、65.50%和66.20%。水旱轮作不施药与旱旱轮作常规施药处理相比,株结果数、株果重和产量分别显著降低15.03%、12.14%和6.33%,株饱果数和出仁率分别显著提高13.88%和3.01%,株根瘤个数显著提高166.22%;水旱轮作减施药与旱旱轮作常规施药处理相比,株结果数、株果重、产量、百仁重和出仁率均无显著差异,株饱果数显著提高14.33%,株根瘤个数显著提高122.97%。表明水旱轮作模式对花生果腐病和蛴螬有较理想的防控效果,且使花生产量结构明显优化,根瘤菌数量显著提高。     

Persistence of benomyl and thiophanate compounds in soil and various plants following soil application

Control ofSclerotinia sclerotiorum in muskmelons was obtained by a single soil drench with benomyl. The material was found in the apical parts of the plant and in the soil until the end of the growing season. Benomyl [methyl l-(butylcarbamoyl)-2-benzi-midazolecarbamate] and thiophanate methyl-NF 44 [1.2- bis (3 methoxycarbonyl-2-thioureido) benzene], applied to seedbeds, were taken up by and then persisted in tomato, pepper and eggplant for approximately 8 weeks after application. Thiophanate-NF 35 [1.2-bis (ethoxycarbonyl-2-thioureido) benzene] could be detected only in the bottom leaves of pepper and eggplant, for up to 4 weeks after application.     

微生物菌肥对熏蒸剂处理后土壤微生态的影响研究进展

土壤熏蒸是防治土传病害的有效手段,但化学熏蒸剂在杀死病原微生物的同时也会对有益微生物群落的组成与活性造成影响。微生物菌肥不仅能够减少农作物的病虫害侵染,而且能够改善农产品的品质与产量。将土壤熏蒸剂与微生物菌肥配合使用将有利于连作土壤修复、土壤-植物微生态环境的改良与重塑。一方面,土壤熏蒸剂用于消灭前茬作物遗留下的土壤病原物,给土壤进行消毒处理;另一方面,施用微生物菌肥给“纯净”的土壤环境输入有益菌群,引导更利于植物生长的土壤微生态环境(土壤理化性质、土壤微生物群落结构)形成。本文简述了土壤熏蒸剂、微生物菌肥以及微生物菌肥介入熏蒸后的土壤对土壤理化性质、土壤酶系及土壤微生物群落变化的研究进展,旨在系统解析微生物菌肥对经熏蒸剂处理后土壤微环境变化的影响,以期为解决连作障碍、防治土传病害、恢复植物根际功能提供相关理论与技术参考。     

The influence of soil and other physical factors on the antifungal activity of carbendazim against Rhizoctonia solani

The inhibition of the growth of Rhizoctohia solani in vitro by carbendazim was maximal at 20°C and at pH 8. In pot tests using mung bean, maximum protection against ‘damping-off’, caused by R. solani, was obtained when seeds were treated with carbendazim. at 1 g a. i. kg^?1 (as a wettable powder) and sown in river sands of pH 7 and 8, kept at a 20°C. Better disease control was obtained in soils kept moist by frequent watering than in soils under water stress. Disease control was best in sandy soil and least in clay loam. The implications of these results, for the antifungal efficacy of carbendazim under diverse soil conditions, are discussed.     

Metabolism of some sterol inhibitors in fungi and higher plants,with special reference to the selectivity of fungicidal action

The metabolism of triforine, chloraniformethan, the α-(pyrimidin-5-yl)benzhydryl alcohols (fenarimol, nuarimol and triarimol), the trityl-azoles (fluotrimazole and clotrimazole), and the morpholine types of sterol inhibitors is reviewed; the metabolism of the azolyl-alkane derivatives (mainly triadimefon and triadimenol) is discussed in detail. Redox and hydrolytic reactions are of primary importance. Enzymic inactivation may be one factor influencing fungicide selectivity. Metabolism is the dominant factor of selectivity if it represents the activation process, as with triadimefon. Transformations in higher plants do not differ significantly from those occurring in fungi, except that factors such as the formation of conjugates with natural compounds of plant tissues also play a role, as with triforine and triadimenol. The selectivity of fungitoxic action may be influenced by metabolism both in the host plant and the pathogen.