福建省玉米小斑病菌对丙环唑、烯唑醇和咪鲜胺的敏感性

为明确玉米小斑病菌对丙环唑、烯唑醇和咪鲜胺的敏感性,采用菌丝生长速率法测定了自福建省15个市、县分离的185株玉米小斑病菌对3种药剂的敏感性。结果显示:供试菌株对丙环唑、烯唑醇和咪鲜胺的EC50值分别在0.0186~7.779、0.0416~22.32和0.0053~7.930μg/mL之间。敏感性频率分布图显示,玉米小斑病菌群体中已出现对丙环唑、烯唑醇和咪鲜胺敏感性降低的亚群体。以连续单峰频次分布的大多数菌株群体的EC50平均值(0.5199±0.0284)、(0.4079±0.0204)和(0.3818±0.0202)μg/mL分别作为玉米小斑病菌对丙环唑、烯唑醇和咪鲜胺的相对敏感基线,发现各有15.14%、20.00%和17.30%的菌株对丙环唑、烯唑醇和咪鲜胺产生了抗性,抗性倍数最高分别为14.96、54.71和20.77。玉米小斑病菌对3种杀菌剂之间具有显著的交互抗性,而丙环唑和烯唑醇之间的交互抗性相关系数最高,为0.8662。本研究结果可为田间玉米小斑病防控杀菌剂的合理使用提供理论依据。     

药剂对稻曲病菌的毒力测定及复配研究

为筛选防治稻曲病的有效单剂和复配组合,采用菌丝生长速率法,测定烯唑醇、腈菌唑、丙环唑、咪鲜胺、苯菌灵、多菌灵、戊唑醇、井冈霉素、松脂酸铜9种杀菌剂及互相复配后对稻曲病菌的毒力,并比较了不同复配组合的协同作用.结果表明:稻曲病菌对烯唑醇最敏感,EC5o为0.145 μg/mL;井冈霉素对稻曲病菌的毒力作用最弱,EC50为13.6 μg/mL.从252种不同比例复配的药剂中,筛选出12种增效配方,其中烯唑醇和咪鲜胺复配(1∶10),协同系数高达3.70,增效作用最大;烯唑醇和咪鲜胺(1∶10)对稻曲病菌的毒力作用最强,EC5o为0.06μg/mL,其次是烯唑醇和咪鲜胺(1∶20)与烯唑醇和腈菌唑(10∶1),EC50分别为0.10μ/mL和0.11μg/mL.田间试验结果也表明:烯唑醇与咪鲜胺(1∶10)复配,对稻曲病的平均防效为79.2％,高于其他常用药剂.     

三七圆斑病菌槭菌刺孢对嘧菌酯、咪鲜胺和苯醚甲环唑的敏感性及生存适合度分析

采用菌丝生长速率法测定了采自云南省5个三七主要产区的34株三七圆斑病原菌槭菌刺孢Mycocentrospora acerina (R. Hartig) Deighton对嘧菌酯、咪鲜胺和苯醚甲环唑的敏感性，并对不同敏感性菌株进行了生存适合度测定。结果表明:咪鲜胺、嘧菌酯及苯醚甲环唑对所有供试槭菌刺孢的菌丝生长均有明显的抑制作用，3种杀菌剂的EC₅₀值分别在0.03~1.91 mg/L、0.18~2.36 mg/L和0.45~2.15 mg/L之间，即该菌株对咪鲜胺的敏感性对高于嘧菌酯和苯醚甲环唑；低敏感性菌株的致病力和菌丝生长速率与敏感性菌株间无显著差异，说明供试槭菌刺孢菌株在当地均具有较高的生存适合度。     

湖北省小麦赤霉病菌对多菌灵、戊唑醇和咪鲜胺的敏感性

对2014年采自中国湖北省7个县、市的206株小麦赤霉病菌样品进行单孢分离与鉴定,并采用菌丝生长速率法随机测定了其中100株菌株对多菌灵、戊唑醇和咪鲜胺的敏感性,建立了其敏感基线。结果表明:多菌灵、戊唑醇和咪鲜胺对湖北省小麦赤霉病菌的EC50值范围分别为0.115~0.705、0.006~1.356和0.002~0.370 μg/mL,平均值分别为0.248、0.181和0.040 μg/mL;供试100株小麦赤霉病菌对3种药剂的敏感性频率均呈单峰拟正态分布,因此可将所得各EC50平均值分别作为湖北省小麦赤霉病菌对3种药剂的敏感基线参考值。以各药剂EC50平均值的10倍作为敏感性鉴别浓度,对2015及2016年湖北省小麦赤霉病菌的敏感性进行了监测,在该鉴别浓度下,多菌灵、戊唑醇和咪鲜胺对2015年小麦赤霉病菌的平均抑制率分别为100%、85.14%和82.35%,对2016年小麦赤霉病菌的平均抑制率分别为100%、76.67%和73.62%。研究表明,虽然戊唑醇和咪鲜胺对2016年小麦赤霉病菌的抑制率略有下降,但整体而言,湖北省小麦赤霉病菌对多菌灵、戊唑醇及咪鲜胺仍具有较高的敏感性。     

江苏省水稻恶苗病菌对咪鲜胺和氰烯菌酯的敏感性

对采自江苏省姜堰、靖江和常州3个地区的水稻恶苗病样品进行了病原菌的分离和鉴定,利用菌丝生长速率法测定了病原菌对咪鲜胺和氰烯菌酯的敏感性。结果表明:分离得到77株水稻恶苗病菌Fusarium fujikuroi;咪鲜胺对水稻恶苗病菌的EC50值在0.020~1.333μg/m L之间,分离到的菌株对咪鲜胺均表现为中抗和高抗,其中中抗菌株18株,占23.38%,高抗菌株59株,占76.62%,说明咪鲜胺高抗菌株已经成为江苏省的恶苗病菌优势群体。氰烯菌酯(JS399-19)对水稻恶苗病菌的EC50值在0.012~2.040μg/m L之间,菌株的敏感性频率近似正态分布,EC50均值为(0.684±0.265)μg/m L,建议将此值作为江苏省水稻恶苗病菌对氰烯菌酯的敏感性基线。     

2013年湖北省小麦赤霉病菌对多菌灵和戊唑醇的敏感性

2013年从湖北省7个小麦主产区分离获得106株禾谷镰刀菌,测定了其对戊唑醇和多菌灵的敏感性。结果表明:戊唑醇和多菌灵对所有供试菌株的EC50值分别为0.064~0.778和0.090~0.858 mg/L。采用SAS软件的W法对EC50分布进行了正态性检验,表明106株菌株对戊唑醇和多菌灵敏感性的频率分布符合正态分布,其EC50平均值分别为(0.383±0.129)和(0.526±0.151)mg/L。不同地区来源的菌株对两种药剂的敏感性存在显著差异,其中襄阳的菌株对两种药剂的敏感性显著低于其他6个地区的。研究结果显示:湖北省小麦赤霉病菌未出现对戊唑醇和多菌灵抗性菌群,两种药剂用于防治小麦赤霉病仍具有使用价值。     

辽宁省稻瘟病菌对咪鲜胺敏感基线的建立

2011年从辽宁省不同地区采集分离了81株稻瘟病菌Magnaporthe grisea,利用菌丝生长速率法分别测定了其对咪鲜胺的敏感性。结果表明:供试菌株中最敏感菌株的EC50值为0.008 8 μg/mL,最不敏感菌株的EC50值为0.178 0 μg/mL,敏感性差异达19倍。供试菌株敏感性频率呈近似正态分布,初步确定将所有菌株的EC50平均值0.071 0 μg/mL±0.041 0 μg/mL作为辽宁省稻瘟病菌对咪鲜胺的敏感基线。     

滇黄精炭疽病菌的初步鉴定及其对3种杀菌剂的敏感性

对2019年采集自云南省3个滇黄精产区的炭疽病菌进行形态学及ITS序列分子鉴定，并采用菌丝生长速率法，测定了40株黄精炭疽病菌对氟啶胺、咪鲜胺和苯醚甲环唑的敏感性。结果表明:从滇黄精炭疽病病叶上分离得到的40株炭疽病菌可能分别属于炭疽菌属中的胶孢炭疽菌Colletotrichum gloeosporioides、果生炭疽菌C. fructicola、博宁炭疽菌C. boninense和尖孢炭疽菌C. acutatum，其中果生炭疽菌29株，占总分离菌株的72.5%，为优势病原菌。3种杀菌剂对 40 株供试菌株的菌丝生长有明显的抑制作用，氟啶胺、咪鲜胺和苯醚甲环唑的EC₅₀ 值分别介于0.028~0.53 mg/L、0.018~2.69 mg/L 和 0.158~2.57 mg/L 之间，即供试菌株对氟啶胺的敏感性高于其对咪鲜胺和苯醚甲环唑的敏感性。目前，3个滇黄精产区的炭疽病菌尚未对氟啶胺、咪鲜胺和苯醚甲环唑产生抗药性。     

10种杀菌剂对水稻稻叶褐条斑病菌的室内毒力

为了解化学药剂对水稻稻叶褐条斑病病菌的抑制作用,采用菌丝生长速率法,测定了10种杀菌剂对稻黑孢霉菌［Nigrosporaoryzae Berk.etBr.Petch］的敏感性。结果表明：各药剂对稻黑孢霉菌的毒力差异显著。10%苯醚甲环唑水分散粒剂、25%吡唑醚菌酯乳油、50%咯菌腈可湿性粉剂对稻黑孢霉菌毒力居前列,EC50分别为0.5072、0.6398、0.9959mg/L,其次是50%咪鲜胺锰盐可湿性粉剂、30%苯甲·丙环唑乳油、12. 5%氟环唑悬浮剂、25%氟环·醚菌酯悬浮剂,EC50在1. 3803~2. 1182 mg/L,毒力较弱的是40%稻瘟灵可湿性粉剂和70%甲基硫菌灵可湿性粉剂,EC50分别为16.3178、17.4257mg/L,毒力最小的是75%百菌清可湿性粉剂,EC50达41. 5957 mg/L。综合各供试药剂的斜率和EC50、EC90,稻黑孢霉菌对测定的苯醚甲环唑、咯菌腈、咪鲜胺锰盐以及苯甲·丙环唑等药剂最为敏感,这些药剂可作防治稻叶褐条斑病的候选药剂。     

8种杀菌剂对黄瓜枯萎病菌的室内毒力测定

采用菌落直径法,分别测定了7大类8种常用杀菌剂对黄瓜枯萎病菌的室内毒力。结果表明,8种供试杀菌剂对黄瓜枯萎病菌的作用效果均较好,其中三唑类丙环唑的毒力最高,EC50值为0.023mg/L。咪鲜胺、苯醚甲环唑、咯菌腈、百菌清和嘧菌酯的毒力也较高,EC50均低于1.0mg/L;多菌灵和异菌脲对黄瓜枯萎病的毒力分别为1.105和1.181mg/L,仍有较好的作用效果。     

Baseline sensitivity and cross-resistance to demethylation-inhibiting fungicides in Ontario isolates of Sclerotinia homoeocarpa

Four hundred and thirty-five isolates of Sclerotinia homoeocarpa from eight populations in southern Ontario were tested for sensitivity to the demethylation-inhibiting (DMI) fungicides, propiconazole, myclobutanil, fenarimol and tebuconazole. The isolates were collected in summer 1994 just prior to legal DMI fungicide use on turfgrass in Ontario. There were wide variations in sensitivities, and seven of the eight populations were very sensitive to the fungicides. Based on mean EC₅₀ and the distribution of DMI sensitivity, one population near the U.S. border was suspected of having been previously exposed to DMI fungicide. Pairwise comparisons of EC₅₀ values for the different fungicides showed low to moderate correlations between fungicides. EC₅₀ values of myclobutanil and propiconazole had the best correlation, followed by the pair of tebuconazole and fenarimol. Other pairwise comparisons were not statistically significant except for a barely significant relationship between EC₅₀ values of myclobutanil and tebuconazole. For field populations of plant pathogens, cross-resistance to different DMI fungicides may not be as strong as conventionally thought. The data collected here will allow comparison to subsequent years to look for detectable shifts in S. homoeocarpa sensitivity to DMI fungicides as they become more frequently used in Ontario.     

Sensitivity of Podosphaera aphanis isolates to DMI fungicides: distribution and reduced cross‐sensitivity

BACKGROUND: Management of strawberry powdery mildew, Podopshaera aphanis (Wallr.), requires numerous fungicide treatments. Limiting epidemics is heavily dependent on sterol demethylation inhibitors (DMIs) such as myclobutanil or penconazole. Recently, a noticeable reduction in the efficacy of these triazole fungicides was reported by strawberry growers in France. The goal of this study was to investigate the state of DMI sensitivity of French P. aphanis and provide tools for improved pest management. RESULTS: Using leaf disc sporulation assays, sensitivity to myclobutanil and penconazole of 23 isolates of P. aphanis was monitored. Myclobutanil EC₅₀ ranged from less than 0.1 to 14.67 mg L^?1 and for penconazole from 0.04 to 4.2 mg L^?1. A cross‐analysis and a Venn diagram showed that there was reduced sensitivity and a positive correlation between the less sensitive myclobutanil and penconazole isolates; 73.9% of isolates were less sensitive to a DMI and 47.8% exhibited less sensitivity to both fungicides. CONCLUSION: The results show that sensitivity to myclobutanil and, to a lesser extent, penconazole has become less efficient in strawberry powdery mildew in France. Therefore, urgent action is required in order to document its appearance and optimise methods of control. Copyright © 2009 Society of Chemical Industry     

Sensitivity of Lasiodiplodia theobromae from Brazilian papaya orchards to MBC and DMI fungicides

Stem rot caused by Lasiodiplodia theobromae is an important postharvest disease of papaya in Brazil, responsible for reducing the quality and quantity of fruits. Fungicide use is one of the main disease management measures. However, there are no estimates available of pathogen sensitivity to commonly employed fungicides. Therefore, the EC₅₀ from 120 isolates of L. theobromae from northeastern Brazil, representative of six populations of the pathogen, was estimated in vitro for fungicides of the methyl benzimidazole carbamates—MBC (benomyl and thiabendazole) and demethylation-inhibiting—DMI (imazalil, prochloraz, tebuconazole) groups. Mycelial growth on fungicide-free media and virulence on papaya fruits of the MBC-sensitive and non-sensitive isolates were compared. For MBCs, 8.4% of isolates were non-sensitive to fungicides. For the remaining 91.6%, the mean EC₅₀ ranged from 0.002 to 0.13 μg ml⁻¹ and 0.36 to 1.27 μg ml⁻¹ for benomyl and thiabendazole, respectively. For DMIs, the mean EC₅₀ range for imazalil was 0.001 to 2.27 μg ml⁻¹, 0.04 to 1.75 μg ml⁻¹ for prochloraz, and 0.14 to 4.05 μg ml⁻¹ for tebuconazole. The EC₅₀ values of non-sensitive isolates were significantly (P≤0.05) higher those for the sensitive isolates for each of the DMI fungicides. Differences (P≤0.05) were found in the levels of sensitivity to DMI fungicides among the isolate populations associated with orchards. The populations from two orchards were less sensitive to DMIs. No solid evidence was found for fitness costs relating to MBC non-sensitive isolates because mycelial growth in fungicide-free media and virulence on papaya fruits were similar to those of sensitive isolates.     

稻田土壤8种真菌对4种杀菌剂的敏感性分析

基于ITS-5.8s rDNA区序列,初步鉴定了浙江大学试验基地稻田土壤的8种常见真菌。采用菌丝生长速率法测定了井冈霉素、多菌灵、咪鲜胺和三唑酮4种常用杀菌剂对这8种土壤真菌的抑菌活性,以及多菌灵与咪鲜胺混用对禾柄锈菌、黑曲霉和长枝木霉3种真菌菌丝生长的抑制作用。结果表明:8种真菌对咪鲜胺最敏感,EC50值在0.091~3.1 mg/L之间;多菌灵的EC50值在0.15~1.8 mg/L之间;三唑酮的EC50值在0.57~8.5 mg/L之间;井冈霉素的敏感性最低,EC50在12~94 mg/L之间。由4种杀菌剂的SSDs曲线分析结果得出,不同真菌对杀菌剂敏感性存在显著差异。当多菌灵与咪鲜胺按其EC50值分别以体积比3∶2、1∶1和7∶3混用时,增效系数分别为1.615、1.039和1.042,表现出一定的协同或相加作用。本研究结果为进一步阐明杀菌剂对稻田生态系统真菌群落的生态效应及杀菌剂的科学合理使用提供了重要依据。     

芒果炭疽病菌的抑菌植物筛选及肉桂油抑菌活性测定

以芒果炭疽病菌抗药性菌株、敏感菌株为研究材料,用生长速率法筛选出了一批高效抑菌植物,大部分植物的丙酮提取物对芒果炭疽病菌有不同程度的抑制作用,其中:肉桂、丁香、藿香的提取物活性最强,在干物质质量浓度为0.025 g/mL下抑制率达100%;芒果炭疽病菌抗药性菌株对肉桂等植物提取物无明显抗性;肉桂油对芒果炭疽病菌敏感菌株(ZJS)和抗药性菌株(JZR)的抑制中浓度(EC50)分别为98.9和71.2 mg/L,而肉桂醛对ZJS和ZJR的EC50值分别为20.7和20.2 mg/L。     

白术黑斑病菌对甲基硫菌灵和腐霉利的抗性检测及对咪鲜胺敏感性基线的建立

黑斑病是影响白术种植的主要病害之一,2015—2017年从浙江省磐安、天台、新昌和嵊州4地采集、分离得到137株白术黑斑病菌Alternaria alternata,采用菌丝生长速率法检测其对甲基硫菌灵和腐霉利的抗性。结果表明:供试的黑斑病菌群体 (n = 137) 对甲基硫菌灵的高水平抗性频率为77.4%,中等水平抗性频率为22.6%,未检测到敏感菌株;对腐霉利的抗性频率为20.4%,含21株低水平抗性菌株和7株中等水平抗性菌株。7种杀菌剂的室内毒力测定结果表明:咪鲜胺对白术黑斑病菌的活性最高,EC₅₀值为0.15 mg/L。供试的137株白术黑斑病菌对咪鲜胺的EC₅₀值分布在0.05~0.87 mg/L之间,平均EC₅₀值为 (0.29 ± 0.11) mg/L,可作为敏感性基线。     

Sensitivity of <Emphasis Type="Italic">Cochliobolus heterostrophus</Emphasis> to three demethylation inhibitor fungicides,propiconazole, diniconazole and prochloraz,and their efficacy against southern corn leaf blight in Fujian Province,China

Southern corn leaf blight (SCLB) caused by Cochliobolus heterostrophus is a fungal disease that impacts production of corn in China. Fungicides have been the main strategy to manage SCLB. In this study, 276 isolates of C. heterostrophus from seven locations in Fujian Province of China were tested for sensitivity to three demethylation inhibitor (DMI) fungicides. The results indicated that most of the isolates of C. heterostrophus tested were exceptionally sensitive to the three DMI fungicides. Correlation analysis revealed positive association between propiconazole and diniconazole (r?=?0.8145, P?<?0.0001), propiconazole and prochloraz (r?=?0.6190, P?<?0.0001), and diniconazole and prochloraz (r?=?0.5784, P?<?0.0001). However, there was no cross-resistance between these three DMI fungicides and the other six fungicides tested, which included carbendazol, chlorothalonil, mancozeb, iprodione, fluazinam, and pyraclostrobin. In a preventive pot experiment, one spray of 25% propiconazole emulsifiable concentrate (EC) with 250 μg active ingredient (a.i.) mL^?1 applied 12 and 24 h before inoculation at the seedling (V6) stage reduced severity of SCLB by 85.60–89.21%. Nevertheless, the curative activity of propiconazole was much weaker (P?<?0.05) than its preventive efficacy. In greenhouse pot assays, one dose of propiconazole at 250 μg a.i. mL^?1 was the most efficacious for controlling SCLB at the seedling and tasseling (VT) stages of corn, decreasing severity by 80.31%–84.85%, which was higher (P?<?0.05) compared to diniconazole, prochloraz, and other reference fungicides. Therefore, propiconazole appears to be very effective in reducing SCLB and should be applied as a preventive rather than therapeutic fungicide. Our findings provide essential information on the evolution of DMI resistance in C. heterostrophus in Fujian Province of China and may serve as a guide for early resistance monitoring in the future.     

烟草赤星病菌对苯醚甲环唑和氟环唑敏感性测定及田间防效试验

为明确山东省主要烟草产区烟草赤星病菌Alternaria alternata对苯醚甲环唑和氟环唑的敏感性,采用菌丝生长速率法检测苯醚甲环唑和氟环唑对86株烟草赤星病菌菌株的EC_(50),用Spearman’s秩相关系数法分析供试菌株对2种杀菌剂敏感性的相关性,并评价其对烟草赤星病的田间防效。结果表明,苯醚甲环唑对烟草赤星病菌菌丝生长EC_(50)值介于5.3883～8.0316 mg/L之间,平均值为6.9594 mg/L,敏感性频率分布呈连续性偏正态分布,田间烟草赤星病菌对苯醚甲环唑仍然较为敏感,可建立田间烟草赤星病菌对苯醚甲环唑的敏感基线。氟环唑对烟草赤星病菌菌丝生长的EC_(50)值介于0.1253～0.2517 mg/L,平均值为0.1773 mg/L,敏感性频率分布呈连续性偏正态分布,可建立田间烟草赤星病菌对氟环唑的敏感基线。相关性分析结果表明,烟草赤星病菌对苯醚甲环唑和氟环唑敏感性之间不存在明显的相关性。田间试验结果表明,30%苯醚甲环唑悬浮剂对烟草赤星病具有较好的防效,其有效成分150 g/hm~2处理的防效最高,为73.99%;12.5%氟环唑悬浮剂对烟草赤星病的最高防效为70.57%。表明2种三唑类杀菌剂对烟草赤星病防效较好。