黄瓜霜霉病菌对甲霜灵的抗药性治理

霜霉病是黄瓜的主要病害之一,目前主要依靠化学防治来减轻其危害.甲霜灵(metalaxyl)是苯基酰胺类杀菌剂的代表品种.我国20世纪80年代引进该药剂不久,霜霉病菌Pseudoperonospora cubensis就对甲霜灵产生了抗性.在过去10余年中,抗性治理多采用药剂替换或混用技术.作者采用不同作用机制的药剂来制定用药流程,进行了黄瓜霜霉病菌对甲霜灵的抗药性治理.     

我国云南、湖北和山东葡萄产区霜霉病菌对甲霜灵的抗性检测

为明确我国云南省宾川县、湖北省公安县和山东省烟台市葡萄产区霜霉病菌对甲霜灵的抗性发生态势,采用叶盘漂浮法测定了这3个产区共127株葡萄霜霉病菌对甲霜灵的抗性频率及抗性水平。结果显示,不同区域间病菌的抗性频率和抗性水平均存在差异。其中,湖北省公安县霜霉病菌的抗性频率和抗性水平均较高,抗性频率达92.0%,高抗菌株占76.0%,低抗菌株占16.0%,敏感菌株占8.0%;山东省烟台市霜霉病菌的抗性频率为74.0%,低抗菌株占64.0%,高抗菌株占10.0%,敏感菌株占26.0%;云南省宾川县霜霉病菌的抗性频率和抗性水平均较低,抗性频率为29.6%,敏感菌株占70.4%,低抗菌株占29.6%,无高抗菌株。     

太原市郊区黄瓜霜霉病菌对甲霜灵的抗药性检测

对太原市郊区黄瓜主要种植区黄瓜霜霉病菌对甲霜灵的抗药性进行了检测,结果表明:来自于8个不同地区的黄瓜霜霉病菌对甲霜灵的抗性频率均为100%。在检测的27个菌株中有2个中抗菌株,12个高抗菌株,13个特高抗菌株,无敏感菌株。     

马铃薯晚疫病菌对烯酰吗啉的敏感性基线及其室内抗药突变体的研究

 2003-2004年在内蒙古和黑龙江省共分离获得100株马铃薯晚疫病菌,并测定了这些菌株对烯酰吗啉和甲霜灵的敏感性。结果表明,不同地区、不同年份的马铃薯晚疫病菌对烯酰吗啉的敏感性无显著差异,其敏感性呈连续的单峰曲线分布,EC₅₀在0.0631-0.2206μg/mL之间,最不敏感菌株是最敏感菌株的3.1倍,平均为(0.1153±0.0308)μg/mL,未出现敏感性下降的抗药性亚群体,因此可作为马铃薯晚疫病菌对烯酰吗啉的敏感性基线;64%的供试菌株对甲霜灵的敏感性下降,甲霜灵与烯酰吗啉之间不存在交互抗药性。采用紫外线诱变菌丝的方法仅从3个菌株中的1个菌株获得了3%突变频率的抗烯酰吗啉突变体,抗性倍数为1.5-1.9,没有获得高抗药水平的突变体。这些突变体与氟吗啉之间具有正交互抗药性,而与霜脲氰或嘧菌酯之间无交互抗药性;与野生亲本菌株相比,抗药突变体的生长速率和产孢子囊能力显著下降,不利于抗药群体的发展。但由于马铃薯晚疫病菌被杀菌剂抗性行动委员会认为是高抗药性风险病原菌,建议生产上应将烯酰吗啉与其它无交互抗性的药剂交替使用或混合使用,以避免或延缓抗药性的产生。     

河北省黄瓜霜霉病菌对甲霜灵和嘧菌酯的抗性动态及七种药剂的田间防效

为明确黄瓜霜霉病菌对甲霜灵和嘧菌酯的抗性动态及相应药剂对黄瓜霜霉病的田间防效,采用叶盘漂浮法监测了2011—2015年河北省黄瓜霜霉病菌对甲霜灵和嘧菌酯的抗性,采用茎叶喷雾法测定了含甲霜灵或精甲霜灵的混剂及嘧菌酯单剂等7种药剂的田间防效。结果表明:采自河北省不同地区的838株黄瓜霜霉病菌对甲霜灵和嘧菌酯普遍产生抗性,抗性频率为100.00%,抗性倍数为482.99和354.97,黄瓜霜霉病菌对甲霜灵和嘧菌酯的抗性随着监测地区和监测年限而波动,唐山、沧州、石家庄、衡水、廊坊和保定市的菌株对甲霜灵和嘧菌酯的抗性指数高于其它地区,黄瓜霜霉病菌对甲霜灵和嘧菌酯的抗性指数在不同年度间高位波动。按照田间推荐剂量喷施,250 g/L嘧菌酯悬浮剂对黄瓜霜霉病的防效为72.15%~74.13%;68%精甲霜灵·代森锰锌水分散粒剂和58%甲霜灵·代森锰锌可湿性粉剂的防效分别为65.30%~70.19%和63.26%~68.35%,与80%代森锰锌可湿性粉剂防效相当;50%烯酰吗啉可湿性粉剂、250 g/L双炔酰菌胺悬浮剂和687.5 g/L氟吡菌胺·霜霉威盐酸盐悬浮剂的防效达82.00%以上,对黄瓜霜霉病具有较好的防效,在黄瓜霜霉病菌对嘧菌酯、甲霜灵和精甲霜灵产生抗性的地区,可作为替代或混配药剂使用。     

葡萄白腐病菌对福美双抗药性的测定

从辽宁省不同地区采集到27株葡萄白腐病菌株。应用菌丝生长速率法测定各菌株对福美双的抗药水平。结果表明,不同地区采集的葡萄白腐病菌抗药性存在着差异,出现高抗性菌株,抗性频率为74.07%。在离体条件下,抗药性菌株表现出较高的抗药稳定性。菌丝生长速率和菌丝鲜重与病菌抗药水平有显著的相关性,而产孢量与抗药水平无相关性。     

霜脲氰与不同杀菌剂混配对两种霜霉病菌的增效作用

采用叶盘法（定量喷药）测定霜脲氰与不同杀菌剂混配对黄瓜和葡萄霜霉病菌抗甲霜灵菌株的增效作用,证实了霜脲氰加代森锰锌或二者再加恶霜灵以不同比率混配对黄瓜、葡萄霜霉病菌均明显增效,发现了霜脲氰与碱式硫酸铜1：8混配对黄瓜霜霉病菌增交,代森锰锌（1：8）或再加恶霜灵（1：8：1）对葡萄霜霉病菌的增效作用随着供试菌株对甲霜灵抗性水平的提高而增强。霜脲氰与代森锰锌1：7混配以保护、治疗、铲除方式处理黄瓜叶盘,对黄瓜霜霉病菌均表现增效。     

噁唑菌酮与精甲霜灵复配对葡萄霜霉病的防效及药剂在葡萄中的残留

为明确噁唑菌酮与精甲霜灵复配在防治葡萄霜霉病上的可行性及安全性,对噁唑菌酮与精甲霜灵进行了室内联合毒力测定、田间药效及残留试验.结果表明:噁唑菌酮与精甲霜灵按质量比1:1复配,对葡萄霜霉病的联合毒力表现为增效作用,EC50值为2.52 mg/L,共毒系数(CTC)为154.53.30％ 噁唑菌酮 ? 精甲霜灵悬浮剂(噁...     

马铃薯晚疫病菌对甲霜灵抗性机制的初步研究

 选取对甲霜灵敏感、中抗和高抗的马铃薯晚疫病菌(Phytophthora infestans)菌株各2株,采用电导率法和同位素掺入法,研究了甲霜灵对马铃薯晚疫病菌不同抗药性水平菌株细胞膜通透性和RNA聚合酶活性的影响,借助液相色谱分析方法检测了不同抗药性水平菌株对甲霜灵的降解作用。结果表明:甲霜灵对马铃薯晚疫病菌不同抗药性水平菌株的细胞膜通透性没有明显影响;随着甲霜灵浓度提高,敏感菌株的RNA聚合酶活性受到显著抑制,10μg/mL甲霜灵对敏感菌株RNA聚合酶活性的抑制率达到40%以上,而10和100μg/mL甲霜灵对高抗菌株的RNA聚合酶活性只表现轻微的抑制作用,抑制作用分别小于8%和21%,甲霜灵对中抗菌株RNA聚合酶活性的抑制作用介于对敏感菌株和高抗菌株的抑制作用之间。抗性菌株对甲霜灵有一定的降解作用,培养30d后高抗菌株HL105和SC1的降解率分别达到13.46%和16.14%。     

黄瓜霜霉病菌抗氟吗啉菌株的适合度研究

 采用离体叶盘法和活体植株法,测定了从田间分离获得的对氟吗啉具有抗药性的黄瓜霜霉病菌菌株和通过室内紫外线诱变获得的对氟吗啉及对照药剂烯酰吗啉和嘧菌酯产生抗药性的突变菌株的生存适合度。试验结果表明,室内诱导获得的氟吗啉和烯酰吗啉抗药性突变菌株的适合度明显低于敏感菌株和嘧菌酯抗药性突变体及田产氟吗啉抗药性菌株,主要表现在菌株的侵染率、产孢能力和致病力的减弱。室内获得的氟吗啉和烯酰吗啉抗药性突变体和敏感菌株混合接种、继代培养后,其抗药菌株的检出率在混合群体中逐渐降低,其中抗性突变体FR4和敏感菌株以2:8的比例混合接种、培养7代后,其无性后代中检测不到抗药性菌株的存在,表明室内氟吗啉抗药性突变体竞争力弱于敏感菌株;而田间氟吗啉抗药性菌株和室内嘧菌酯抗药性突变体则表现出和敏感菌株相似或更强的竞争力,预示田间自然情况下抗药性菌株存在着可能形成优势菌群而导致药剂防治失败的潜在风险。     

Fungicide modes of action and resistance in downy mildews

Among oomycetes, Plasmopara viticola on grape and Phytophthora infestans on potato are agronomically the most important pathogens requiring control measures to avoid crop losses. Several chemical classes of fungicides are available with different properties in systemicity, specificity, duration of activity and risk of resistance. The major site-specific fungicides are the Quinone outside inhibitors (QoIs; e.g. azoxystrobin), phenylamides (e.g. mefenoxam), carboxylic acid amides (CAAs; e.g. dimethomorph, mandipropamid) and cyano-acetamide oximes (cymoxanil). In addition, multi-site fungicides such as mancozeb, folpet, chlorothalonil and copper formulations are important for disease control especially in mixtures or in alternation with site-specific fungicides. QoIs inhibit mitochondrial respiration, phenylamides the polymerization of r-RNA, whereas the mode of action of the other two site-specific classes is unknown but not multi-site. The use of site-specific fungicides has in many cases selected for resistant pathogen populations. QoIs are known to follow maternal, largely monogenic inheritance of resistance; they bear a high resistance risk for many but not all oomycetes. For phenylamides, inheritance of resistance is based on nuclear, probably monogenic mechanisms involving one or two semi-dominant genes; resistance risk is high for all oomycetes. The molecular mechanism of resistance to QoIs is mostly based on the G143A mutation in the cytochrome b gene; for phenylamides it is largely unknown. Resistance risk for CAA fungicides is considered as low to moderate depending on the pathogen species. Resistance to CAAs is controlled by two nuclear, recessive genes; the molecular mechanism is unknown. For QoIs and CAAs, resistance in field populations of P. viticola may gradually decline when applications are stopped.     

Monitoring of QoI fungicide resistance in Plasmopara viticola populations in Japan

BACKGROUND: The increasing occurrence of QoI fungicide resistance in Plasmopara viticola (Berk. & MA Curtis) Berl. & DeToni populations is becoming a serious problem in the control of grapevine downy mildew. In Japan, the existence of QoI‐fungicide‐resistant P. viticola was reported in 2009. RESULTS: The QoI fungicide resistance in P. viticola samples collected from vineyards in Japan in 2008 and 2009 was monitored. Resistant P. viticola were detected in the regions where QoI fungicides have been introduced in accordance with the pest management programme, whereas in Hokkaido vineyards, where QoI fungicides have not yet been introduced, QoI‐fungicide‐resistant P. viticola were not found. CONCLUSION: Japan comprises thousands of islands and is physically isolated from other countries by the sea. Monitoring the emergence, incidence and distribution of QoI fungicide resistance in P. viticola populations in Japan is necessary to improve pest management strategies for downy mildew disease in Japanese vineyards. Copyright © 2010 Society of Chemical Industry     

Resistance to acylalanines in Pseudoperonospora cubensis1

Resistance to acylalanine fungicides in Pseudoperonospora cubensis, the downy mildew of cucurbits, is reviewed. Insensitive strains of the fungus predominated during the second year of metalaxyl application in cucumber glasshouses in Greece and Israel. Resistance was detected either on detached cucumber leaves floated on metalaxyl solutions or on potted plants treated (sprayed or drenched) with this fungicide. Metalaxyl-resistant strains of P. cubensis showed good pathogenicity and fitness, and competed favorably with the sensitive strains in the absence of the fungicide. A synergism between these two biotypes resulted in an increased virulence of the resistant forms on metalaxyl-treated plants. Metalaxyl-resistant strains of the pathogen exhibited cross resistance to other acylalanine fungicides. Strains resistant to acylalanines and to the chemically unrelated oomycete-fungicides fosetyl-Al and propamocarb were isolated in Israel, as well. In Greece, however, protective sprays with fosetyl-Al, cymoxanil and mancozeb gave good control of cucumber downy mildew when the pathogen was resistant to metalaxyl. P. cubensis is the first case of fungus which developed resistance to acylalanines in the field.     

Characterization of European Plasmopara viticola isolates with reduced sensitivity to cymoxanil

Cymoxanil has been used for over 30 years to control grape downy mildew (Plasmopara viticola) in European vineyards, prevalently in mixture with other fungicides active on this disease. In the 1990’s cases of P. viticola resistant to cymoxanil were detected using a leaf disc assay. In this study, we establish that the presence of only 1 % of resistant isolates in a P. viticola population will allow the detection of cymoxanil resistance in the leaf disc assay. A poor correlation (R?=?0.194) was observed between the leaf disc assay and a whole- plant test for 38 P. viticola field populations collected in 2004. Over 60 % of these populations were characterized as fully sensitive in a whole-plant assay compared to 10 % in the leaf disc assay. Five P. viticola field isolates resistant to cymoxanil reverted to full sensitivity after six to nine transfers to untreated vines, indicating that cymoxanil resistance in P. viticola is unstable. Two European P. viticola populations sensitive to cymoxanil became resistant when transferred 12–14 times on vines treated with cymoxanil. In contrast, two populations originating from the USA and three monozoospore isolates from France retained full sensitivity to the fungicide after 13 cycles on cymoxanil-treated plants. Whole-plant experiments were conducted in the laboratory to compare the efficiency of spray programs to delay the development of cymoxanil resistance. Whereas the continuous use of cymoxanil alone quickly selected for resistance, the mixture of cymoxanil and folpet applied either continuously or in strict or block alternation effectively prevented the development of resistance over 10 generations of the fungus. These results demonstrate that resistance to cymoxanil in P. viticola can be managed with appropriate spray programs.     

Selection for fungicide resistance throughout a growing season in populations of Plasmopara viticola

A method for evaluating the potential threat of selection for resistance to organically-based fungicides in populations of P. viticola is needed to screen a large panel of products alternative to copper in organic viticulture. Populations from an unexposed plot were compared throughout one season with a population sprayed with azoxystrobin (Quadris), reported as engendering selection pressure and resistance, and a population sprayed with an organically-based fungicide (Mycosan). The evolution of the three populations was followed with neutral specific SSR markers and with the specific marker for strobilurin resistance, as control of selection for resistant mutants. A reduction in genetic diversity of the P. viticola population was observed in the population sprayed with azoxystrobin, consistent with directional selection toward higher resistance, confirmed by an enhanced frequency of resistant mutants with respect to the unexposed population. In contrast, a higher diversity and a reduced frequency of resistant mutants were observed in the population sprayed with the organically-based fungicide. Assessing a reduction of genotypic diversity allows the detection of selection for resistance and constitutes a valid instrument for screening a large panel of products with non-specific, different and possibly indirect modes of action.     

宁夏葡萄霜霉病菌致病型鉴定及葡萄品种抗性评价

为合理利用葡萄抗性品种以及田间病害综合治理，采用离体叶盘接种法分别对2018年和2019年自宁夏回族自治区银川市、石嘴山市和吴忠市采集的43株葡萄霜霉病菌Plasmopara viticola菌株进行致病型鉴定及聚类分析，并对17个主栽葡萄品种进行抗性评价及聚类分析。结果表明：2018、2019年供试菌株致病力和供试葡萄品种抗性之间均存在显著差异，菌株平均病情指数与发病率呈显著正相关，皮尔逊相关系数r和回归系数R²分别介于0.45~0.96和0.20~0.92之间；2018、2019年供试菌株的强致病力菌株和弱致病力菌株分别为CS-YL和VI-BYDD、RG-JSJG和CS-YM；2018年和2019年供试菌株致病型被划分为强、中、弱3种类群，2年所占比例分别为10.00%、15.00%、75.00%和34.78%、39.13%、26.09%；供试17个葡萄品种的抗性类型可被划分为感病、抗病、高抗3种类群，2年所占比例均为17.65%、29.41%和52.94%。不同葡萄品种对不同菌株的抗性类型多样化。表明宁夏回族自治区葡萄霜霉病菌菌株致病力分化明显，不同菌株的致病型与其地域来源无关，不同葡萄品种的抗感程度不同。     

樟树枝叶提取物防治葡萄霜霉病的效果

为明确樟树枝叶提取物对葡萄霜霉病的防治效果,采用混合液滴显微镜观察法研究了樟树枝叶提取物及其活性成分对病原菌孢子囊萌发的抑制作用,利用高效液相色谱法鉴定了枝叶乙酸乙酯萃取物的化学成分,测定了其活性成分对葡萄霜霉病的室内和田间防治效果。结果表明,浓度为0.1 g/mL以上的樟树枝叶提取物对孢子囊萌发均有很好的抑制效果,抑制率达100.0%;樟树枝叶提取物经不同极性有机溶剂萃取后,分别获得正己烷、乙酸乙酯、正丁醇和水相分离物,浓度为1.0%时各分离物对孢子囊萌发的抑制率分别为58.4%、92.4%、32.5%和58.7%,乙酸乙酯相富集了主要抑菌活性成分,经液相色谱分析并与色谱库数据比对,确定其活性成分中含有芦丁和槲皮素;浓度为1.0%的芦丁和槲皮素对孢子囊具有抑制作用;田间试验显示,浓度为0.3 g/mL以上的枝叶提取物对葡萄霜霉病预防效果显著,治疗效果在60.0%以上。研究表明,樟树枝叶提取物可以有效控制葡萄霜霉病,提取物的活性成分芦丁和槲皮素可以作为植物源药剂。     

Resistance to acylalanines in Phytophthora infestans in The Netherlands1

In The Netherlands in 1980 a severe late-blight epidemic involving metalaxyl-resistant strains of Phytophthora infestans did considerable damage to the potato crop. As a consequence metalaxyl or metalaxyl-containing products were withdrawn from the Dutch fungicide market for the control of potato late blight. In 1981 the majority of the P. infestans isolates obtained from various parts of the country were sensitive to metalaxyl. In three areas where metalaxyl mixtures were used on a relatively large scale metalaxyl-resistant strains dominated the population. Incidental use of metalaxyl mixtures in 1982 and 1983 showed adequate late-blight control and, when in 1984 an early and in some areas severe epidemic developed, a metalaxyl/mancozeb mixture was reintroduced for curative application in combination with conventional fungicides. Although disease control was adequate, resistant strains were present in a small number of fields. Whether resistant strains will increase in frequency and threaten the usefulness of mixtures of acylalanines will heavily depend on how well potato farmers adopt strategies involving a limited use of mixtures of acylalanines in a spray schedule with conventional late-blight fungicides.     

抗氟吡菌胺辣椒疫霉菌株的诱导及其生物学特性的研究

 采用菌丝生长速率法, 测定了采自泰安、平谷、杭州和昆明4个地区的42株辣椒疫霉病菌对氟吡菌胺的敏感性, 结果表明, 其EC₅₀值在0.618 ~0.927 μg·mL^-1之间, 平均EC₅₀ =(0.743±0.067 7) μg·mL^-1。 42个菌株对氟吡菌胺的敏感性分布呈单峰曲线, 未出现抗性的病原菌亚群体, 可将其单峰曲线作为辣椒疫霉对氟吡菌胺的敏感性基线。采用药剂驯化和紫外照射对辣椒疫霉敏感菌株TA进行诱变处理, 获得了2株辣椒疫霉抗氟吡菌胺菌株;利用菌落直径法测定抗氟吡菌胺菌株的遗传稳定性、菌丝生长速率及对其它杀菌剂的交互抗性;通过活体叶盘法测定抗氟吡菌胺菌株和敏感菌株的致病力及产孢子囊能力, 分析抗性和敏感菌株之间生物学特性差异。结果表明, 敏感菌株TA经过氟吡菌胺 48代连续汰选, 其抗性达58.0倍, 获得中抗菌株TA-R;紫外照射获得了抗性达260.6倍的高抗菌株TA-UV, 且其抗性均能稳定遗传;TA-R和TA-UV对甲霜灵、霜脲氰表现出正交互抗性, 对烯酰吗啉、百菌清、代森锰锌和丙森锌无交互抗性;抗氟吡菌胺菌株TA-R、TA-UV与敏感菌株在活体叶盘上的致病力、离体产孢能力均差异不显著(P＜0.05), 但其菌丝生长速率、菌丝干重均低于敏感菌株。     

Method for rapid detection of the PvCesA3 gene allele conferring resistance to mandipropamid, a carboxylic acid amide fungicide, in Plasmopara viticola populations

BACKGROUND: The occurrence of carboxylic acid amide (CAA)‐fungicide‐resistant Plasmopara viticola populations is becoming a serious problem in the control of grapevine downy mildew worldwide. RESULTS: The authors have developed a method, which utilises PCR‐RFLP, for the rapid detection of resistance to the CAA fungicide mandipropamid in P. viticola populations. With this method, a glycine‐to‐serine substitution at codon 1105 of the cellulose synthase gene PvCesA3 of CAA‐fungicide‐resistant P. viticola was easily detected, although no resistant P. viticola was detected from 398 isolates in Japan. CONCLUSION: It is proposed that the PCR‐RFLP method is a reliable tool for the rapid detection of CAA‐fungicide‐resistant P. viticola isolates. Only 4 h was required from the sampling of symptoms to the phenotyping of fungicide resistance. Copyright © 2011 Society of Chemical Industry