含单萜酚结构酰胺类杂合分子的设计与合成及抑菌活性

为寻找具有良好抑菌活性的酰胺类化合物,本研究将天然单萜酚类化合物香芹酚和百里香酚与琥珀酸脱氢酶抑制剂(SDHI)药效团拼合,设计并合成了30个酰胺类杂合分子,其结构经核磁共振氢谱(1H NMR)、碳谱(13C NMR)及高分辨质谱(HRMS)等确认。采用菌丝生长速率法测定了目标化合物对5种植物病原真菌的抑菌活性。结果表明,目标化合物对茄链格孢菌Alternaria solani和灰葡萄孢Botrytis cinerea的抑菌活性较好,其中 7e (N-(4-羟基-5-异丙基-2-甲基苯)-3-甲基噻吩-2-酰胺)的活性最高,对茄链格孢菌和灰葡萄孢的EC₅₀值分别为3.28和15.06 μg/mL,且 7e 与啶酰菌胺之间没有交互抗性。琥珀酸脱氢酶(SDH)活性测定表明, 7e 对灰葡萄孢敏感、抗性和B-P225F突变菌株的SDH均具有较强的抑制活性。分子对接研究表明, 7e 与野生型和突变型灰葡萄孢琥珀酸脱氢酶(BcSDH)之间具有较强的亲和力;推测 7e 是潜在的新型SDHI,其与啶酰菌胺之间对菌株SDH抑制活性的差异和与野生型和突变型BcSDH之间结合模式的差异,可能是二者之间没有交互抗性的原因。     

樱桃褐腐病菌对啶酰菌胺的敏感性及其对4种琥珀酸脱氢酶抑制剂的交互抗性

采用菌丝生长速率法测定了樱桃褐腐病菌Monilinia fructicola对啶酰菌胺的敏感性,同时研究了不同敏感性菌株的生物学性状,探究了琥珀酸脱氢酶B亚基的氨基酸突变与其对啶酰菌胺产生抗性的相关性,并分析了樱桃褐腐病菌对啶酰菌胺与其他3种琥珀酸脱氢酶抑制剂(SDHIs)氯苯醚酰胺、氟唑菌苯胺和氟吡菌酰胺之间的交互抗...     

啶酰菌胺不同抗性类型多主棒孢的生物学特性

由多主棒孢Corynespora cassiicola引起的黄瓜棒孢叶斑病是黄瓜上的重要病害。本研究测定了对啶酰菌胺不同抗性类型多主棒孢的生物学特性差异和环境适合度，旨在为探明多主棒孢对啶酰菌胺的抗性变化机制提供生物学研究基础。随机选取不同地区24株对啶酰菌胺具有不同抗性类型的多主棒孢，分析了7种类型抗性突变体对几种不同琥珀酸脱氢酶抑制剂类 (SDHIs) 杀菌剂的交互抗性、不同抗性类型多主棒孢在无药剂选择压力下的抗性遗传稳定性，以及抗性突变体在不同碳源、氮源、温度等环境条件下的生物学特性及适合度。结果表明:除突变类型SdhB-H278Y及SdhB-H278R对啶酰菌胺与氟吡菌酰胺之间存在负交互抗性外，其他突变类型对啶酰菌胺与吡噻菌胺、氟吡菌酰胺及萎锈灵之间均表现为正交互抗性；所有突变类型菌株的抗药性均能稳定遗传；不同突变类型菌株之间致病性存在差异，其中SdhD-D95E突变体的致病力最强；利于所有突变类型菌株生长的碳源是麦芽糖，氮源种类则对突变体的生长影响不显著；各突变类型菌株的最适生长温度范围为25~30 ℃，其中突变体SdhD-D95E在高于30 ℃条件下菌丝生长速率大于其他突变体；耐热性研究中，抗性突变体经65 ℃高温处理45 min后无法存活，同时发现，60 ℃条件下突变体能正常生长，而敏感菌株不能生长；各质量浓度NaCl处理下，SdhD-D95E突变菌株菌丝生长速率快于其他突变菌株，而SdhB-H278Y突变菌株慢于其他突变菌株；葡萄糖对SdhB-H278R突变菌株的生长较为重要。研究表明，对啶酰菌胺不同抗性类型多主棒孢突变菌株的生物学特性及适合度存在差异，SdhD-D95E突变菌株适合度有所提高，表明该突变类型多主棒孢在田间具有较强的竞争力，容易形成优势种群。     

上海市草莓灰霉病菌对氟吡菌酰胺敏感性检测及 抗性分子机制

为明确上海地区草莓灰霉病菌 Botrytis cinerea 对琥珀酸脱氢酶抑制剂类(succinate dehydrogenase inhibitors, SDHIs)杀菌剂氟吡菌酰胺的敏感性水平及抗性机制, 本研究采用菌丝生长速率法测定了2019年上海市5个草莓主产区的90个灰葡萄孢菌株对氟吡菌酰胺的抗性, 并分析了菌株的琥珀酸脱氢酶(SHD)亚基序列?结果显示:敏感性频率分布基线呈一个连续单峰曲线, 符合正态分布, 平均EC50为1.68±0.91)μg/mL, 氟吡菌酰胺对上海地区草莓灰霉病菌菌丝生长的EC50最低值为0.09 μg/mL, 最高值为75.91 μg/mL?根据新建立的抗性划分标准, 发现上海奉贤区已存在抗氟吡菌酰胺的菌系, 抗性频率72.77%, 抗性菌株的最高抗性倍数为45.18, 其他地区抗性频率较低, 浦东新区和嘉定区分别为25.00%和4.76%, 崇明?青浦区菌株的抗性频率均为0?已有抗性的菌群抗性突变位点在 Sdh B亚基的N230I位和P225F位这二个位点, 突变后分别导致低抗?中抗菌株的产生?     

不同抗性型灰葡萄孢菌Botrytis cinerea对不同作用机制杀菌剂的敏感性研究

不同类型杀菌剂对灰葡萄孢菌菌株的离体、活体毒力测定结果表明 ,苯并咪唑类的多菌灵、甲基硫菌灵之间 ,二甲酰亚胺类的腐霉利、异菌脲、菌核净之间表现交互抗性 ;苯并咪唑类和 N -苯氨基甲酸酯类乙霉威表现有负交互抗性趋势。离体测定中 ,对不同类型菌株以吡咯类杀菌剂咯菌腈 (EC50 200mg/ L) ,咯菌腈以及甾醇抑制剂戊唑醇、氟硅唑和丙环唑均表现出较高的活性。     

浙江省果蔬灰葡萄孢对啶酰菌胺的抗性

以2004—2006年从浙江、江苏等地采集的灰葡萄孢对啶酰菌胺的敏感性基线[EC₅₀ = (1.07 ± 0.11) mg/L]为依据,采用菌丝生长速率法连续监测了浙江省果蔬灰葡萄孢群体对啶酰菌胺的敏感性变化。结果表明:浙江省果蔬灰葡萄孢对啶酰菌胺的抗性发展迅速,2012—2013年和2017—2018年的平均EC₅₀值分别为 (5.23 ± 7.79) 和 (24.30 ± 49.33) mg/L。其中,2012—2013年的抗药性菌株频率为15.3%,且均为低水平抗性 (LR) 菌株;而2017—2018年的抗药性频率上升至53.2%,并出现了7.5%的中等水平抗性 (MR) 菌株和1.3%的高水平抗性 (HR) 菌株。啶酰菌胺抗性菌株的菌丝生长速率、产孢量、产菌核数和致病力与敏感菌株相比均无显著差异。抗药性分子机制研究表明:啶酰菌胺抗性菌株的琥珀酸脱氢酶B亚基 (SDH B) 均发生了点突变,共包括H272R、P225F和N230I 3种类型,其中H272R型突变占88.5%;其SDH A和SDH D均未发生点突变;而SDH C的突变 (G85A + I93V + M158V + V168I) 与对药剂敏感性之间无明显联系。     

灰葡萄孢对氟啶胺的敏感性检测及敏感性降低菌株生物学性状研究

为评价灰霉病菌对氟啶胺的敏感性及抗药性风险，本试验于2020年-2021年在吉林、江西、湖北、山东、北京、湖南等地区的草莓、辣椒、四季豆、茄子和番茄上采集病叶、病茎、病花和病果，经单孢分离获得117个灰葡萄孢Botrytis cinerea菌株，采用菌丝生长速率法测定其对氟啶胺的敏感性。结果表明：有4株灰葡萄孢BJ14、BJ45、BJ46和BJ47对氟啶胺的敏感性显著降低，EC₅₀在0.113 7～0.394 6μg/mL,抗性倍数为4.7～16.3,MIC值>4μg/mL。其余113个菌株对氟啶胺的平均EC₅₀为0.025 1μg/mL。敏感性降低的4个菌株继代培养10代后，抗药性状稳定。交互抗性测定结果表明，对氟啶胺敏感性下降的菌株对腐霉利和咯菌腈2种杀菌剂表现为敏感，氟啶胺与腐霉利或咯菌腈没有交互抗性。生物学性状研究表明，4株敏感性下降菌株在PDA平板上的生长速率和在番茄果实上的致病力都显著低于敏感菌株，而菌丝生物量、产孢量和孢子萌发率与敏感菌株无显著差异。以上研究结果表明，田间已存在对氟啶胺敏感性降低的菌株，鉴于灰葡萄孢属于高风...     

辽宁省番茄灰霉病菌对氟吡菌酰胺的敏感性

从辽宁省番茄产区未使用过琥珀酸脱氢酶抑制剂的温室采集番茄灰霉病样本,经分离、鉴定并纯化,得到病原菌(Botrytis cinerea Pers.)单孢菌株206株,采用菌丝生长速率法测定氟吡菌酰胺的有效抑制中浓度EC50,建立了敏感基线,并调查了氟吡菌酰胺与咯菌腈、啶酰菌胺、嘧霉胺、腐霉利、异菌脲之间的交互抗性情况.结...     

西瓜蔓枯病菌啶酰菌胺抗性突变体的生物学特性研究及其Sdh B基因位点检测

为评价西瓜蔓枯病菌对啶酰菌胺的抗性风险,了解其抗性机理,室内通过药剂驯化方法获得2株啶酰菌胺的抗性突变体XF21-3和YC60-1,测定了抗性突变体的生物学特性,并通过对Sdh B基因片段的测序比对,分析了西瓜蔓枯病菌对啶酰菌胺的抗性机理。生物测定结果表明:啶酰菌胺对2株抗性突变体的EC50值分别为108和124 μg/mL,抗性倍数（RR）分别为1 007和1 347,均为高抗菌株;抗性突变体的菌丝生长速率和产孢量均大于亲本菌株,但其致病性与亲本菌株无显著差异,对外界环境渗透压的敏感性低于亲本菌株;此外,啶酰菌胺与萎锈灵、戊唑醇、乙霉威及醚菌酯之间均不存在交互抗性,但与噻呋酰胺之间存在交互抗性。Sdh B基因片段测序及比对结果表明,高抗性突变体中Sdh B亚基277位上的氨基酸所对应的碱基由CAC突变为TAC,即由组氨酸（His）突变为酪氨酸（Tyr）。研究表明,西瓜蔓枯病菌在药剂选择压力下容易形成啶酰菌胺的抗性群体,且抗性突变体的离体适合度高于亲本菌株,此外,啶酰菌胺与同类型杀菌剂噻呋酰胺之间存在交互抗性,因此认为西瓜蔓枯病菌对啶酰菌胺具有中等抗性风险;同时进一步验证了Sdh B亚基277位上的氨基酸突变（His→Tyr,CAC→TAC）是西瓜蔓枯病菌对啶酰菌胺产生抗性的原因。     

两种新型琥珀酸脱氢酶抑制剂的抑菌活性比较

采用菌丝生长速率法、孢子萌发法和幼苗法比较了吡唑萘菌胺和氟吡菌酰胺对23种病原菌的毒力。结果表明,吡唑萘菌胺对黄瓜褐斑病菌、黄瓜炭疽病菌、辣椒炭疽病菌、番茄早疫病菌、苹果斑点病菌、辣椒疫霉病菌、马铃薯晚疫病菌、番茄灰霉病菌、番茄菌核病菌、水稻稻瘟病菌和苹果轮纹病菌菌丝生长均有较高的抑制活性,其EC50值为0.10~9.52μg/mL,EC90值为1.87~62.23μg/mL。吡唑萘菌胺对花生白绢病菌、苹果腐烂病菌、棉花黄萎病菌、棉花立枯病菌和镰刀菌属病原菌的抑制活性均高于氟吡菌酰胺,而氟吡菌酰胺却对黄瓜褐斑病菌、番茄早疫病菌、苹果斑点病菌、番茄灰霉病菌、番茄菌核病菌和苹果褐斑病菌具有较高的抑制活性,其EC50值为0.39~3.98μg/mL,与吡唑萘菌胺相当。吡唑萘菌胺对玉米丝黑穗、花生冠腐病菌和番茄灰霉病菌的孢子有较高的毒力,其EC50值分别为0.002 9、0.07和1.38μg/mL。氟吡菌酰胺仅对花生冠腐病菌、番茄灰霉病菌的孢子有较高的活性,且它与吡唑萘菌胺活性相当。吡唑萘菌胺和氟吡菌酰胺对黄瓜白粉病菌均有较高的毒力,EC50值分别为0.04、0.05μg/mL。因此,吡唑萘菌胺比氟吡菌酰胺更加广谱,且抑菌活性相当或更高。     

Screening and characterization of resistance to succinate dehydrogenase inhibitors in Alternaria solani

Field isolates of Alternaria solani, which causes early blight of potato in Idaho, USA were evaluated in vitro for their sensitivity towards the succinate dehydrogenase inhibitor (SDHI) fungicides boscalid, fluopyram and penthiopyrad. A total of 20 isolates were collected from foliar‐infected tissue in 2009, 26 in 2010 and 49 in 2011. Fungicide sensitivity was tested using the spiral‐gradient end point dilution method. The frequency of boscalid‐resistant isolates (>50% relative growth when using a spiral dilution gradient starting at 507 mg L^?1) drastically increased over the duration of this study (15% in 2009, 62% in 2010 and 80% in 2011). Increasing resistance to fluopyram and penthiopyrad was observed. However, cross‐resistance was only observed between boscalid and penthiopyrad. The target site of this fungicide class is the succinate dehydrogenase (SDH) enzyme complex, which is vital for fungal respiration. Sequence analysis of the SDH complex revealed mutations in the subunits B and D that were correlated with the emergence of boscalid resistance in potato fields in Idaho. In particular, H277R and H133R were identified in SDH subunits B and D, respectively. The presence of restriction sites in the gene sequences allowed the development of a rapid PCR‐RFLP method to assess boscalid sensitivity in A. solani populations.     

Lack of cross-resistance to a novel succinate dehydrogenase inhibitor, fluopyram, in highly boscalid-resistant isolates of Corynespora cassiicola and Podosphaera xanthii

BACKGROUND: Recently in Japan, isolates resistant to boscalid, a succinate dehydrogenase inhibitor (SDHI), have been detected in Corynespora cassiicola (Burk. & Curt.) Wei and Podosphaera xanthii (Castaggne) Braun & Shishkoff, the pathogens causing Corynespora leaf spot and powdery mildew disease on cucumber, respectively. Resistant isolates of C. cassiicola are widely distributed and represent a serious problem in disease control at present. Novel SDHI fungicides, including fluopyram, are now under development. RESULTS: The growth of very highly boscalid‐resistant, highly resistant and sensitive isolates of C. cassiicola was strongly suppressed on fluopyram‐amended YBA agar medium. Although boscalid and another SDHI, penthiopyrad, hardly controlled Corynespora leaf spot and powdery mildew on cucumber plants when very highly or highly boscalid‐resistant isolates were employed for inoculation, fluopyram still exhibited excellent control efficacy against these resistant isolates as well as sensitive isolates of C. cassiicola and P. xanthii. CONCLUSION: Differential sensitivity to boscalid, penthiopyrad and fluopyram, clearly found in these two important pathogens of cucumber, may indicate involvement of a slightly distinct site of action for fluopyram from the two other SDHIs. This finding may lead to the discovery of unique SDHIs in the future. Copyright © 2011 Society of Chemical Industry     

Molecular characterization of boscalid resistance in field isolates of Botrytis cinerea from apple

Botrytis cinerea isolates obtained from apple orchards were screened for resistance to boscalid. Boscalid-resistant (BosR) isolates were classified into four phenotypes based on the levels of the concentration that inhibited fungal growth by 50% relative to control. Of the 220 isolates tested, 42 were resistant to boscalid, with resistant phenotypes ranging from low to very high resistance. There was cross resistance between boscalid and carboxin. Analysis of partial sequences of the iron-sulfur subunit of succinate dehydrogenase gene in B. cinerea (BcSdhB) from 13 BosR and 9 boscalid-sensitive (BosS) isolates showed that point mutations in BcSdhB leading to amino acid substitutions at the codon position 272 from histidine to either tyrosine (H272Y) or arginine (H272R) were correlated with boscalid resistance. Allele-specific polymerase chain reaction (PCR) analysis of 66 BosR isolates (including 24 additional isolates obtained from decayed apple fruit) showed that 19 carried the point mutation H272Y and 46 had the point mutation H272R, but 1 BosR isolate gave no amplification product. Analysis of the BcSdhB sequence of this isolate revealed a different point mutation at codon 225, resulting in a substitution of proline (P) by phenylalanine (F) (P225F). The results indicated that H272R/Y in BcSdhB were the dominant genotypes of mutants in field BosR isolates from apple. A multiplex allele-specific PCR assay was developed to detect point mutations H272R/Y in a single PCR amplification. Levels of boscalid resistance ranged from low to very high within isolates carrying either the H272R or H272Y mutation, indicating that, among BosR isolates, different BosR phenotypes (levels of resistance) were not associated with particular types of point mutations (H272R versus H272Y) in BcSdhB. Analysis of genetic relationships between 39 BosR and 56 BosS isolates based on three microsatellite markers showed that 39 BosR isolates and 30 BosS isolates were clustered into two groups, and the third group consisted of only BosS isolates, suggesting that the development of resistance to boscalid in B. cinerea likely is not totally random, and resistant populations may come from specific genetic groups.     

Molecular characterization of boscalid- and penthiopyrad-resistant isolates of Didymella bryoniae and assessment of their sensitivity to fluopyram

BACKGROUND: Didymella bryoniae has a history of developing resistance to single‐site fungicides. A recent example is with the succinate‐dehydrogenase‐inhibiting fungicide (SDHI) boscalid. In laboratory assays, out of 103 isolates of this fungus, 82 and seven were found to be very highly resistant (B^VHR) and highly resistant (B^HR) to boscalid respectively. Cross‐resistance studies with the new SDHI penthiopyrad showed that the B^VHR isolates were only highly resistant to penthiopyrad (B^VHR‐P^HR), while the B^HR isolates appeared sensitive to penthiopyrad (B^HR‐P^S). In this study, the molecular mechanism of resistance in these two phenotypes (B^VHR‐P^HR and B^HR‐P^S) was elucidated, and their sensitivity to the new SDHI fluopyram was assessed. RESULTS: A 456 bp cDNA amplified fragment of the succinate dehydrogenase iron sulfur gene (DbSDHB) was initially cloned and sequenced from two sensitive (B^S‐P^S), two B^VHR‐P^HR and one B^HR‐P^S isolate of D. bryoniae. Comparative analysis of the DbSDHB protein revealed that a highly conserved histidine residue involved in the binding of SDHIs and present in wild‐type isolates was replaced by tyrosine (H277Y) or arginine (H277R) in the B^VHR‐P^HR and B^HR‐P^S variants respectively. Further examination of the role and extent of these alterations showed that the H/Y and H/R substitutions were present in the remaining B^VHR‐P^HR and B^HR‐P^S variants respectively. Analysis of the sensitivity to fluopyram of representative isolates showed that both SDHB mutants were sensitive to this fungicide as the wild‐type isolates. CONCLUSION: The genotype‐specific cross‐resistance relationships between the SDHIs boscalid and penthiopyrad and the lack of cross‐resistance between these fungicides and fluopyram should be taken into account when selecting SDHIs for gummy stem blight management. Copyright © 2011 Society of Chemical Industry     

Non‐target site SDHI resistance is present as standing genetic variation in field populations of Zymoseptoria tritici

BACKGROUND

A new generation of more active succinate dehydrogenase (Sdh) inhibitors (SDHIs) is currently widely used to control Septoria leaf blotch in northwest Europe. Detailed studies were conducted on Zymoseptoria tritici field isolates with reduced sensitivity to fluopyram and isofetamid; SDHIs which have only just or not been introduced for cereal disease control, respectively.

RESULTS

Strong cross‐resistance between fluopyram and isofetamid, but not with other SDHIs, was confirmed through sensitivity tests using laboratory mutants and field isolates with and without Sdh mutations. The sensitivity profiles of most field isolates resistant to fluopyram and isofetamid were very similar to a lab mutant carrying SdhC‐A84V, but no alterations were found in SdhB, C and D. Inhibition of mitochondrial Sdh enzyme activity and control efficacy in planta for those isolates was severely impaired by fluopyram and isofetamid, but not by bixafen. Isolates with similar phenotypes were not only detected in northwest Europe but also in New Zealand before the widely use of SDHIs.

CONCLUSION

This is the first report of SDHI‐specific non‐target site resistance in Z. tritici. Monitoring studies show that this resistance mechanism is present and can be selected from standing genetic variation in field populations. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Mutations in sdh genes in field isolates of Zymoseptoria tritici and impact on the sensitivity to various succinate dehydrogenase inhibitors

Zymoseptoria tritici is the causal agent of septoria tritici blotch (STB), a foliar wheat disease important worldwide. Succinate dehydrogenase inhibitors (SDHIs) have been used in cereals for effective control of STB for several years, but resistance towards SDHIs has been reported in several phytopathogenic fungi. Resistance mechanisms are target‐site mutations in the genes coding for subunits B, C and D of the succinate dehydrogenase (SDH) enzyme. Previous monitoring data in Europe indicated the presence of single isolates of Z. tritici with reduced SDHI sensitivity. These isolates carried mutations leading to amino acid exchanges: C‐T79N, C‐W80S in 2012; C‐N86S in 2013; B‐N225T and C‐T79N in 2014; and C‐V166M, B‐T268I, C‐N86S, C‐T79N and C‐H152R in 2015. The current study provides results from microtitre and greenhouse experiments to give an insight into the impact of different mutations in field isolates on various SDHIs. In microtitre tests, the highest EC₅₀ values for all tested SDHIs were obtained with mutants carrying C‐H152R. Curative greenhouse tests with various SDHIs confirmed the findings of microtitre tests that isolates with C‐H152R are, in general, controlled with lower efficacy than isolates carrying B‐T268I, C‐T79N and C‐N86S. SDHI‐resistant isolates of Z. tritici found in the field were shown to have cross‐resistance towards all SDHIs tested. So far, SDHI‐resistant isolates of Z. tritici have been found in low frequencies in Europe. Therefore, FRAC recommendations for resistance management in cereals, including a limited number of applications, alternation and combination with other MOAs, should be followed to prolong SDHI field efficacy.     

上海地区草莓灰霉病菌对啶酰菌胺的敏感性检测及抗性机制分析

为明确上海地区草莓灰霉病菌Botrytis cinerea Pers. 对主要防治药剂啶酰菌胺的敏感性水平及抗性机制,采用平皿法检测了采自上海市6个区县的195株草莓灰霉病菌株对啶酰菌胺的敏感性,并分析了其中20株不同敏感型菌株的琥珀酸脱氢酶基因序列。结果显示:啶酰菌胺对上海地区草莓灰霉病菌菌丝生长的EC₅₀最小值为0.15 μg/mL,最大值大于110 μg/mL;对孢子萌发的EC₅₀最小值为0.19 μg/mL,最大值大于50 μg/mL。上海地区草莓灰霉病菌对啶酰菌胺的抗性频率为29.74% (抗性水平大于10),高抗频率为20.51% (抗性水平大于100)。该抗性的产生与琥珀酸脱氢酶SdhB亚基发生H272R或P225F突变有关,其中H272R突变发生较为普遍。研究表明,上海地区草莓灰霉病菌对啶酰菌胺的抗性水平及抗性频率较高,主要抗性机制为病原菌琥珀酸脱氢酶SdhB亚基上的H272R突变。     

Biological activity of the succinate dehydrogenase inhibitor fluopyram against Botrytis cinerea and fungal baseline sensitivity

BACKGROUND: Succinate dehydrogenase inhibitors (SDHIs) constitute a fungicide class with increasing relevance in crop protection. These fungicides could play a crucial role in successful management of grey mould disease. In the present study the effect of fluopyram, a novel SDHI fungicide, on several developmental stages of Botrytis cinerea was determined in vitro, and the protective and curative activity against the pathogen was determined on strawberry fruit. Furthermore, fungal baseline sensitivity was determined in a set of 192 pathogen isolates. RESULTS: Inhibition of germ tube elongation was found to be the most sensitive growth stage affected by fluopyram, while mycelial growth was found to be the least sensitive growth stage. Fluopyram provided excellent protective activity against B. cinerea when applied at 100 µg mL^?1 96, 48 or 24 h before the artificial inoculation of the strawberry fruit. Similarly, fluopyram showed a high curative activity when it was applied at 100 µg mL^?1 24 h post‐inoculation, but, when applications were conducted 48 or 96 h post‐inoculation, disease control efficacy was modest or low. The measurement of baseline sensitivity showed that it was unimodal in all the populations tested. The individual EC₅₀ values for fluopyram ranged from 0.03 to 0.29 µg mL^?1. In addition, no correlation was found between sensitivity to fluopyram and sensitivity to other fungicides, including cyprodinil, fenhexamid, fludioxonil, iprodione, boscalid and pyraclostrobin. CONCLUSIONS: The obtained biological activity, baseline sensitivity and cross‐resistance relationship data suggest that fluopyram could play a key role in grey mould management in the near future and encourage its introduction into spray programmes. Copyright © 2011 Society of Chemical Industry