Sensitivities of Phytophthora infestans to Metalaxyl, Cymoxanil, and Dimethomorph

The isolates of Phytophthora infestans on tomato in the Guangxi Zhuang Autonomous Region, China, were determined for the sensitivities to metalaxyl, cymoxanil and dimethomorph to give the basic information for integrating disease management. Sensitivities were tested by measuring the radial growth on agar medium amended with fungicide, compared with the floating-leaf-disk method. 239 isolates were collected from eight tomato growing areas during 2000-2006. The testing results indicated that the frequencies of sensitive, intermediate, and resistant isolates to metalaxyl were 42.26, 35.98, and 23.53%, respectively. Variations in sensitivities amongst isolates from different areas or different years were very high for metalaxyl. All isolates from Tianlin and Wuxuan were sensitive to metalaxyl, but the metalaxyl-resistant isolates predominated in Tianyang, with the frequency of 51.35%. The EC50 values of certain isolates from Tianyang were higher than 500 μg·mL^-1 and their resistance levels were over 100 000 folds. Cymoxanil has been used for nearly 10 years in Guangxi, and dimethomorph has been used for 5-6 years. However, there was no decrease in sensitivity of P. infestans populations and the sensitivities of the pathogen were nearly normally distributed. Hence, their mean ECs0 value [cymoxanil （0.1647 ±0.0255） μg·mL^-1, dimethomorph （0.0970 ± 0.0052） μg·mL^-1 could be used as the baseline sensitivities for monitoring the field resistance development. The comparison with the floating-leaf-disk method indicates that both the techniques provided equivalent results. These studies suggested that metalaxyl can be continuously applied in Tianlin, Wuxuan, and Nanning due to the resistant isolates that have not been found, while for those areas with resistant isolate, the use of metalaxyl should be reduced or alternated, and cymoxanil or dimethomorph was recommended for controlling late blight disease of tomato.

甲霜灵(Metalaxyl)种衣剂防治辣椒苗期疫病效果的初步研究

用甲霜灵 (Metalaxyl)为杀菌剂研制的 2 %甲霜灵种衣剂 ,用量在 6 %以内对辣椒出苗生长安全 ,防治辣椒苗期疫病效果达到 98% ,持效期约 30d左右 ,持效期比 2 5 %甲霜灵WP增加 15d。经气质联用仪分析测定 ,2 %甲霜灵种衣剂包衣后在辣椒幼苗体内含量高于 2 5 %甲霜灵WP拌种处理。

Microbial detoxification of metalaxyl in aquatic system

Four microorganisms, Pseudomonas sp. （ER2）, Aspergillus niger （ER6）, Cladosporium herbarum （ER4） and Penicilluim sp. （ER3）, were isolated from cucumber leaves previously treated with metalaxyl using enrichment technique. These isolates were evaluated for detoxification of metalaxyl at the recommended dose level in aquatic system. The effect of pH and temperature on the growth ability of the tested isolates was also investigated by measuring the intracellular protein and mycelia dry weight for bacterial and fungal isolates, respectively. Moreover, the toxicity of metalaxyl after 28 d of treatment with the tested isolates was evaluated to confirm the complete removal of any toxic materials （metalaxyl and its metabolites）. The results showed that the optimum degree pH for the growth of metalaxyl degrading isolates （bacterial and fungal isolates） was 7. The temperature 30℃ appeared to be the optimum degree for the growth of either fungal or bacterial isolates. The results showed that Pseudomonas sp. （ER2） was the most effective isolate in metalaxyl degradation followed by Aspergillus niger （ER6）, Cladosporium herbarum （ER4） and Penicilluim sp. （ER3）, respectively. There is no toxicity of metalaxyl detected in the supematant after 28 d of treatment with Pseudomonas sp. （ER2）. The results suggest that bioremediation by Pseudomonas sp. （ER2） isolate was considered to be effective method for detoxification of metalaxyl in aqueous media.

Determination of Metalaxyl Residues in Watermelon and Banana by HPLC

A determination method for metalaxyl （MEL） residues in watermelon and banana had been established by automated solid-phase extraction （SPE） cou- pled with high performance liquid hromatography （HPLC）. Samples were extracted by acetonitrile, homogenized, filtrated, extracted by automated solid-phase ex- traction （SPE）, and finally purified by C18 column. The experiment was carried on SunFireTM C18 column with the mobile phase of acetonitrile-water-methanol （25： 40： 35, by vol） at the flow rate of 1.0 mL/min. The detection wavelength and injection volume were set at 220 nm and 10 uL, respectively. The recoveries of three different concentrations （0.02, 0.20, 1.00 mg/kg） for watermelon and banana were 94.3 % - 101.0% and 81.5% - 99.6%, respectively. RSD （ n = 5 ） were 1.30% -5.29% and 2.66% -6.67%, respectively. The lower detection limit for metalaxyl was 0. 006 mg/kg. This method met with the requirements of pesticide residue detection. Key words Metalaxyl; HPLC; Watermelon; Banana

Field Efficacy Evaluation of 68% Metalaxyl-M·Mancozeb WDG against Dendrobium officinale Blight

The control effect of 68% Metalaxyl-M·Mancozeb WDG against Dendrobium officinale blight was studied. The results showed that the control effect of 68% Metalaxyl-M·Mancozeb WDG at the dose of 1 133-1 360 mg/kg against D. officinale blight was over 78.4% at 14 d post spraying, which was equivalent to that of control agent 72% Cymoxanil·Mancozeb WP(1 200 mg/kg) and 80% Mancozeb WP(1 143 mg/kg).Therefore, 68% Metalaxyl-M·Mancozeb WDG sprayed at the dose of 1 133-1 360 mg/kg could effectively control the damage of D. officinale blight.

烟草中甲霜灵的手性分离方法差异研究

对比反相液相色谱-串联质谱(RPLC-MS/MS)和超临界流体色谱-串联质谱(SFC-MS/MS)手性分离烟草中甲霜灵的差异。烟草样品经乙腈提取、盐析分层、快速滤过型净化(multi-Plug Filtration Cleanup,m-PFC)柱净化后,分别采用RPLC-MS/MS和SFC-MS/MS进行手性分离。从多个性能参数(分离效率、线性、选择性、回收率、重复性、灵敏度、基质效应等)对两种方法进行了全面比较。采用不同的分离方法,在10~500 ng/mL范围内,甲霜灵的不同异构体均可呈现良好的线性关系(R^(2)≥0.9993)。在各异构体加标浓度为0.1、0.5、2.0 mg/kg水平下,采用不同的分离方法均可获得满意的回收率(88.7%~96.2%)和良好的重复性(RSD<7.0%)。结果表明:RPLC-MS/MS和SFC-MS/MS具有互补性,均适用于手性分离和测定烟草基质中的甲霜灵。

同位素稀释-液相色谱-串联质谱法测定4类水产品中甲霜灵的残留量

提出了同位素稀释-液相色谱-串联质谱法测定鱼、虾、蟹、贝4类水产品中甲霜灵残留量的方法。取样品(5±0.05)g,加入10 ng的内标甲霜灵-d 6,静置10 min,用10 mL含1%(体积分数)乙酸的乙腈溶液涡旋混合、离心。取上清液,于45℃氮吹至0.5 mL以下,加入7.5 mL 20%(体积分数,下同)乙腈溶液混匀,用7.5 mL正己烷去脂,Agela Cleanert S C_(18)固相萃取柱富集净化。所得溶液于45℃氮吹至干,用1 mL 20%乙腈溶液复溶,混匀后过0.22μm针式水相尼龙滤膜,滤液收集至进样小瓶中。以SHISEIDO CAPCELL PAK C_(18)色谱柱为固定相,以不同体积比的0.1%(体积分数)甲酸溶液和乙腈的混合液为流动相进行梯度洗脱,内标法定量。结果表明,甲霜灵标准曲线的线性范围为1.0~100.0μg·L^(-1),检出限(3S/N)为0.5μg·kg^(-1)。以不同品种水产品为空白基质,在1.0,2.0,10.0μg·kg^(-1)等3个浓度水平下,甲霜灵的回收率为93.8%~105%,测定值的相对标准偏差(n=6)均小于13%。

Degradation of the fungicide metalaxyl and its non-extractable residue formation in soil clay and silt fractions

The proportion of organic matter and mineral composition are important factors determining the formation and type of non-extractable residues(NERs) of pesticides in soil. In this study, we investigated the enantioselectivity in degradation and NER formation of the chiral fungicide metalaxyl in soil particle size fractions(silt and clay). Microbial and extracellular enzyme activities during these processes were monitored in incubation of silt and clay samples isolated from sterilized and non-sterilized soil samples collected from a long-term agricultural field experimental site in Ultuna, Sweden. The temporal influence on the fate of the fungicide was noted by short-term(10-d) and long-term(92-d) incubations. Besides the acquisition of quantitative data with gas chromatography-mass spectrometry(GC/MS), stereoselective analyses were performed with chiral GC/MS. Quantitative results pointed to a higher metabolism rate of the pesticide through microbial activity than through extracellular enzyme activity. This was also confirmed by the enantioselective depletion of R-metalaxyl and the subsequent formation of R-metalaxyl acid in microbially active samples from non-sterilized soil. The silt fraction containing a high amount of organic matter exhibited a significant hydrolyzable proportion of metalaxyl NERs that was releasable under alkaline conditions. On the contrary, the clay fraction showed an enhanced affinity for covalently bound residues. Based on our results, we recommend differentiating between reversibly and irreversibly bound proportions of pesticides in persistence and environmental risk assessment because the reversible fraction contained potentially bioavailable amounts of residues that may be released under natural conditions.

液相色谱串联质谱法快速测定水中敌百虫等6种农药

随着《生活饮用水卫生标准》(GB 5749—2022)的实施,越来越多的农药纳入了饮用水水质监测,但与之相配套的检测方法尚不完善。文章建立了快速且同时测定水中敌百虫、甲基硫菌灵、西草净、甲霜灵、稻瘟灵、氟乐灵6种农药的直接进样-液相色谱串联质谱检测方法,样品经聚四氟乙烯滤膜过滤后进入液相色谱串联质谱仪进行检测,检出限为0.02~3.1μg/L。纯水回收率为60.5%~120.3%,精密度为0.5%~6.2%;饮用水回收率为69.3%~129.8%,精密度为0.4%~7.5%;地表水回收率为75.1%~127.2%,精密度为0.5%~5.1%。试验中考察了4种不同滤膜对方法回收率的影响,最终确定选用聚四氟乙烯过滤材料。本方法检测效率高、可靠性好,适用于饮用水及地表水的常规以及应急检测。

精甲霜灵·咯菌腈·嘧菌酯防治花生苗期土传真菌病害效果研究

采用种子包衣研究了精甲霜灵·咯菌腈·嘧菌酯对花生冠腐病和茎腐病防治效果,结果表明:经11%精甲霜灵·咯菌腈·嘧菌酯悬浮种衣剂200、300、400 g a.i./100 kg处理的种子对花生冠腐病和茎腐病的防效分别为81.92%~92.20%和76.36%~86.10%,两处试验田的出苗率为94.88%~95.75%和93.63%~95.25%,分别增产5.78%~13.14%和5.99%~8.40%。综合安全性、防治效果、增产效果,11%精甲霜灵·咯菌腈·嘧菌酯悬浮种衣剂对防治花生苗期土传真菌病害冠腐病和茎腐病具有较好的应用前景,生产上建议使用剂量为300~400 g a.i./100 kg种子。

11%精甲·咯·嘧菌悬浮种衣剂对水稻恶苗病及稻瘟病的防治效果

采用包衣处理的方法研究了11%精甲·咯·嘧菌悬浮种衣剂(FS)不同剂量对种子出苗率的影响及对水稻恶苗病、稻瘟病的防治效果。结果表明,11%精甲·咯·嘧菌FS按照药种质量比(m/m)1∶300、1∶400、1∶500处理后种子出苗率分别为82.67%、86.67%和77.33%,均高于空白对照组75.67%;对水稻恶苗病有很好防效,分别达90.70%、89.53%和88.37%;对水稻稻瘟病的防治效果在10%以下,防效较差。因此,防治稻瘟病不建议用此药,防治水稻恶苗病的药种比(m/m)采用1∶400更为经济有效。

应用GC-MS测定葡萄中的5种农药残留

酿酒葡萄是河北昌黎的主要水果种植品种,由于受海洋气候的影响,当地空气湿热,葡萄病害十分严重,因而农药使用十分频繁,为了评价其农药残留水平,我们采用丙酮提取,凝胶分离,硅胶小柱净化,GC-MS的选择离子方式检测对采集的葡萄样品进行5种农药(百菌清、精甲霜灵、苯醚甲环唑、嘧菌酯、高效氯氟氰菊酯)的残留分析.……

UPLC-MS-MS法同时测定饮用水中乙酰甲胺磷、稻瘟灵、敌百虫、甲霜灵

为推进新生活饮用水卫生标准的实施,建立了同时测定水中乙酰甲胺磷、稻瘟灵、敌百虫以及甲霜灵4种农药的直接进样超高效液相色谱-串联质谱(UPLC-MS-MS)方法。水样过膜后采用C18色谱柱分离,以0.1%甲酸水溶液-甲醇为流动相进行梯度洗脱,采用多反应监测模式进行定性分析,采用外标法进行定量分析。结果表明,该方法线性范围为5~100μg/L,4种农药在出厂水、水源水、龙头水中的平均回收率为91.1%~114.1%,相对标准偏差(RSD)为4.1%~13.1%;乙酰甲胺磷、稻瘟灵、敌百虫、甲霜灵检出限分别为1.78、1.66、1.62、1.86μg/L,能满足实际的水质检测的需求。利用此方法对北京市有代表性的水源水、出厂水及管网水进行了分析与普查工作,4种农药均未检出。该方法简便快速,有较好的精密度和准确度,为保障我国供水安全提供技术支撑。

贵州烟草黑胫病菌对甲霜灵的抗药性测定

为评估贵州烟草黑胫病菌对甲霜灵的抗药性，采用菌落生长速率法，测定了贵州省8个市（州）采集分离的42株烟草黑胫病菌菌株对甲霜灵的抗性。结果表明：贵州8个市（州）菌株的 EC50值为0．2130～4．2497μg/mL，平均值为1．4256μg/mL；毕节市菌株平均 EC50值为0．7158μg/mL，对甲霜灵最敏感，平均抗性倍数为3．655，抗药性最弱；黔西南州菌株平均EC50值为1．4562μg/mL，对甲霜灵表现为不敏感，平均抗性倍数为9．13，抗药性最强。结论：贵州省大部分地区的烟草黑胫病菌已对甲霜灵产生抗性，建议轮换或停止施用。

氧化石墨烯基纳米杀菌剂新剂型研制及其在黄瓜枯萎病防治中的应用

为更好的防治黄瓜枯萎病,以氧化石墨烯为载体,与甲霜灵、恶霉灵分别进行复配,制备出氧化石墨烯-甲霜灵、氧化石墨烯-恶霉灵杀菌剂纳米复合材料。对氧化石墨烯-杀菌剂进行扫描电镜表征和红外光谱表征,并采用菌丝生长速率法和孢子萌发法对氧化石墨烯-杀菌剂进行室内毒力测定。结果表明,m(氧化石墨烯)∶m(甲霜灵)=1∶1,m(氧化石墨烯)∶m(恶霉灵)=1∶1进行复配,在菌丝生长试验中,共毒系数分别为391.16和356.11;在孢子萌发试验中,共毒系数分别为292.35和221.42,对黄瓜枯萎病联合毒力同样表现为增效作用。氧化石墨烯-杀菌剂对黄瓜枯萎病具有良好的抗真菌活性。

精甲霜灵和噁霉灵对甜瓜苗期猝倒病的药效试验

[目的]筛选出精甲霜灵和噁霉灵复配防治甜瓜猝倒病的最佳组配,确定最佳组配制成的30%精甲霜灵·噁霉灵可溶液剂防治甜瓜苗期猝倒病的施药适期、使用方法和剂量。[方法]通过室内毒力测定,确定2个有效成分最佳组配,以精甲霜灵5%、噁霉灵25%制成30%精甲霜灵·噁霉灵可溶液剂进行田间药效试验。[结果]精甲霜灵和噁霉灵对瓜果腐霉病菌菌株的EC50值分别为0.021 6μg/mL和4.164 5μg/mL,说明这2个药剂对瓜果腐霉病菌有很好的抑制作用。精甲霜灵和噁霉灵按1:5、1:7和1:9组配时的共毒系数分别为285.79、160.88和234.19,判定以1:5组配增效作用最好。30%精甲霜灵·噁霉灵可溶液剂800~1 000倍液防治甜瓜苗期猝倒病,第1次施药后7 d,平均防效达74%以上,第2次施药后10 d,平均防效达80%以上,均高于对照药剂平均防效。[结论]在甜瓜苗期猝倒病发生初期以该药剂制剂用量800~1 000倍液、有效成分用量300~375 mg/kg、用水量3 L/m^(2),灌根处理,间隔7 d喷1次,连续施药2次,对甜瓜苗期猝倒病具有较好的防治效果,可用于甜瓜苗期猝倒病的防治。

北方五省(区)马铃薯晚疫病菌对甲霜灵和精甲霜灵的敏感性检测

为了明确我国不同地区马铃薯晚疫病菌对甲霜灵和精甲霜灵的抗性状况,2007-2009年从河北、黑龙江、吉林、辽宁和内蒙古马铃薯主产区采集马铃薯晚疫病菌,采用菌丝生长速率法和叶盘漂浮法测定其对甲霜灵的敏感性,采用叶盘漂浮法测定其对精甲霜灵的敏感性。结果表明:以菌丝生长速率法检测的380株晚疫病菌中和以叶盘漂浮法检测的222株晚疫病菌中对甲霜灵的抗性菌株分别占80%和73.5%;菌丝生长速率法检测结果显示,河北省对甲霜灵的抗性菌株所占频率从2007年的100%降为2008年的66.4%,2009年又回升至74.2%,而吉林和黑龙江两省对甲霜灵的抗性菌株分布频率呈上升趋势。叶盘漂浮法检测的95个菌株中对精甲霜灵的抗性菌株占54.5%,其中河北省40个菌株对精甲霜灵的中间型菌株占优势(62.5%),抗性菌株仅占34.9%,而其他4省55个菌株对精甲霜灵的抗性菌株占优势(69.1%)。受检测的北方五省(区)马铃薯晚疫病菌群体中对甲霜灵和精甲霜灵的抗性菌株已占优势,马铃薯晚疫病菌已普遍对甲霜灵及精甲霜灵产生抗性。在对甲霜灵和精甲霜灵普遍产生抗性的地区,应优先选用与甲霜灵、精甲霜灵作用机理不同的药剂防治马铃薯晚疫病。

马铃薯晚疫病菌对甲霜灵和霜脲氰的敏感性检测

2003～2004年从内蒙古和黑龙江省共采集分离了127株马铃薯晚疫病菌Phytophthora infestans,并在离体条件下测定了这些菌株对甲霜灵和霜脲氰的敏感性.结果表明:在2003年分离的内蒙菌株、2003年及2004年分离的黑龙江菌株中对甲霜灵敏感(MS)的菌株频率分别为86.2%、13.8%、17.8%;虽然霜脲氰在这些地区使用近10年,但病菌群体对该药剂的敏感性没有下降,EC50值分布于0.10～0.35 μg/mL之间,平均EC50值为0.20(±0.06)μg/mL,不同敏感性的菌株频率呈连续的单峰曲线分布,未出现敏感性下降的抗药性亚群体,可作为马铃薯晚疫病菌对霜脲氰抗药性监测的敏感性基线;此外,马铃薯晚疫病菌对甲霜灵和霜脲氰之间没有交互抗药性,霜脲氰对抗甲霜灵和野生敏感菌株具有相同的活性.

马铃薯晚疫病菌在内蒙古和甘肃的交配型分布及对几种杀菌剂的敏感性

1997— 2 0 0 1年在内蒙古自治区和甘肃省马铃薯主产区采集马铃薯晚疫病菌并进行了交配型和药剂敏感性测定。结果为 :采自内蒙古的 14 3株菌中有 14 0株是典型A1交配型、3株是可自育的A1交配型 ;采自甘肃的 4 1株菌中有 4 0株是典型A1交配型、1株为可自育的A1交配型 ;二省都未发现A2交配型。表明内蒙古和甘肃马铃薯主产区的晚疫病菌以A1交配型占绝对优势。对甲霜灵 (metalaxyl)的敏感性测定显示 :内蒙古菌株中有 5 0 .8%表现高度抗性、4 2 .5 %表现中度抗性、只有 6 .7%表现敏感 ,说明内蒙古马铃薯主产区的晚疫病菌普遍对甲霜灵具有了抗性 ;甘肃的菌株中 ,2 6 8%表现高度抗性、2 9.3%表现中度抗性、4 3.9%表现敏感 ;同时发现甲霜灵可刺激某些抗性菌株的生长。试验还测定了 35株菌对烯酰吗啉 (dimethomorph)和腈嘧菌脂 (azoxystrobin)的敏感性 :其中对烯酰吗啉表现敏感的占 94 %、中度敏感的占 6 % ;对腈嘧菌脂敏感的占 71.4 % ,中度敏感的占 2 8.6 % ;未发现对二种药剂高抗或不敏感菌株 ,且烯酰吗啉和腈嘧菌脂与甲霜灵均无交互抗性。

雪莲果中甲霜灵、异菌脲和除虫脲残留量的高效液相色谱测定方法

采用高效液相色谱法测定雪莲果中甲霜灵、异菌脲和除虫脲农药残留量。通过乙腈提取,固相萃取（SPE）净化,Hypersil Gold（4.6 mmi.d.×250 mm,5μm）柱,V（乙腈）∶V（20 mM NH4Ac）=70：30为流动相,柱温30℃,流速1.0mL/min进行分离,进样20μL,2487双波长紫外检测器进行检测。添加回收率为78.4%-92.1%;RSD分别为3.6%-6.3%;甲霜灵,异菌脲和除虫脲检出限分别为0.05,0.04,0.02μg/mL。