Activity of a novel succinate dehydrogenase inhibitor fungicide pyraziflumid against Sclerotinia sclerotiorum

Natural terpene-based derivatives to control postharvest sclerotinia rot and the involved potential mechanism

In an effort to develop novel postharvest preservatives of satisfactory environmental compatibility from natural monoterpene, a series of terpene-based derivatives containing oxime ester were designed and prepared. In this research, the inhibitory effect of target compounds against S. sclerotiorum were evaluated though in vitro and in vivo tests. It was investigated that most compounds exhibited promising antifungal activity, especially compound 4k with EC50 value of 3.02 μg/mL, which was significantly superior to commercial fungicide trifloxystrobin. Notably, compound 4k improved the physicochemical quality of carrot including weight loss, contents of titratable acidity, ascorbic acid, carotenoid, malondialdehyde, and enzymes activities, ensuring post-harvest preservation. Simultaneously, the mycelial morphology, ultrastructure, cell wall permeability, and defense/respiration-related enzymes of S. sclerotiorum were destructed. The preliminary toxicity evaluation of target compounds indicated that the prepared target compounds possessed safety and low toxicity. Additionally, the essential chemical features for activity and interaction mode between molecule and cytochrome bc1 complex were inquired by computer-aid technology. The study provided meaningful insight into formulation of natural terpene-based fresh-keeping agent to resist postharvest decay infected by S. sclerotiorum.

Recent developments in fluorine-containing pesticides

To ensure ongoing sustainability, the modern agrochemical industry is faced with enormous challenges. These arise from provision of high-quality food to increasing water use and environmental impact as well as a growing world population. The loss of previous agrochemicals due to consumer perception, changing grower needs and ever-changing regulatory requirements is higher than the number of active ingredients that are being introduced into the crop protection market. Therefore, the development of novel agrochemicals is essential to provide improved efficacy and environmental profiles. In this context, the introduction of fluorine atoms and fluorine-containing motifs into a molecule is an important method to influence its physicochemical properties. These include, for example, small difluoro- and trifluoromethyl, or trifluoromethoxy groups at aryl or heterocyclic aryl moieties but also fragments like 2,2,2-trifluoroethoxycarbonyl, trifluoromethylsulfonyl, trifluoroacetyl, as well as the so far unusal rest like heptafluoro-iso-propyl. This review gives an overview of recent developments of fluorine-containing pesticides launched over the past 7 years and describes a selection of current fluorine-containing development candidates. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Identification and Quantification of Dimethachlon Degradation Products in Soils and Their Effects on Soil Enzyme Activities

In this study, high-performance liquid chromatography-high-resolution mass spectrometry (HPLC-HRMS, Q-Exactive Orbitrap) and Compound Discoverer 3.3 were used to screen dimethachlon degradation products in soils. Four metabolites 4-(3,5-dichloroanilino)-4-oxobutanoic acid (DCBAA), 3,5-dichloroaniline (3,5-DCA), succinic acid, and muconic acid were confirmed by primary and secondary ion mass spectrometry comparisons between standards and samples. A quantitative analysis method of dimethachlon residues and four metabolites in soils was developed using HPLC-HRMS. Dimethachlon degradation in agricultural soil indoor unsterilized, sterilized, and field environments in three typical areas was measured. Dimethachlon degraded fast with a half-life of less than 1 day in three nonsterile soils. The maximum DCBAA and 3,5-DCA residues during degradation could reach 22.5-35.2% of the initial concentration of the parent dimethachlon. The metabolite DCBAA had a greater impact on soil enzyme activity than the parent dimethachlon.

Fusel oil reaction in pressurized water: characterization and antimicrobial activity

This work aimed to investigate the reaction of fusel oil (FO) with pressurized water in a continuous flow reactor, in order to verify the effect of operating conditions (temperature and alcohol to water ratio) on the formation of reaction products, as well as to potentiate the antimicrobial activity of FO. The characterization of the FO was performed by high resolution mass spectrometry (ESI-TOF) and by a chromatograph coupled to mass spectrometry (GC-MS), and the reaction products were characterized by ESI-TOF and evaluated for antifungal potential. From the results, it was verified that the FO contained 70.58 wt% of isoamyl alcohol and was formed mainly by the organic functions alcohols, aldehydes, ketones and lipids. The reaction mechanisms that prevailed during the reactions conducted in subcritical and supercritical states were dehydration and reduction, respectively, making it possible to identify pyrazine derivatives compounds in the reaction products. The fungus Irpex lacteus showed greater resistance under the application of reaction products, and the products obtained at 300 °C and 400 °C showed an inhibition percentage of 96.07% to Schizophyllum commune and 96.50% to Trametes versicolor, respectively.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-022-03429-3.

Postharvest sclerotinia rot control in carrot by the natural product hinokitiol and the potential mechanisms involved

Sclerotinia rot infected by cosmopolitan fungi Sclerotinia sclerotiorum is a serious and destructive disease in carrot production, especially during their postharvest storage. Natural products with the advantages of environmentally friendly and safety have been widely concerned. This research estimated the impact of hinokitiol against S. sclerotiorum and on the quality of carrots. In vitro and in vivo tests demonstrated that hinokitiol had promising antifungal activities against both carbendazim-susceptible and -resistant isolates of S. sclerotiorum. Importantly, it effectively kept the quality and prolonged the shelf life of carrot by declining the loss of weight, ascorbic acid, carotenoid, and total phenolics content, preventing the formation of malondialdehyde, and enhancing the activities of antioxidant enzymes. Further study found that hinokitiol inhibited the formation of sclerotia by destroying the morphology and the integrality of cell membrane, reduced the pathogenicity by suppressing the synthesis of oxalic acid and exopolysaccharide, declined the activities of enzymes and the gene expression related to sclerotia development in S. sclerotiorum. These information evidenced the great potential of hinokitiol as a natural fresh-keeping agent for the management of postharvest decay infected by S. sclerotiorum.

Comparative Transcriptome Analyses Reveal Conserved and Distinct Mechanisms of the SDHI Fungicide Benzovindiflupyr Inhibiting Colletotrichum

Colletotrichum leaf disease (CLD) is an annual production concern for commercial growers worldwide. The succinate dehydrogenase inhibitor (SDHI) fungicide benzovindiflupyr shows higher bioactivity against CLD than other SDHIs. However, the mechanism underlying such difference remains unclear. In this study, benzovindiflupyr exhibits good inhibitory activity against Colletotrichum siamense and C. nymphaeae in vitro and in vivo. To reveal its mechanism for inhibiting Colletotrichum, we compared transcriptomes of C. siamense and C. nymphaeae under treatment with benzovindiflupyr and boscalid. Benzovindiflupyr exhibited higher inhibitory activity against SDH enzyme than boscalid, resulting in a greater reduction in the ATP content of Colletotrichum isolates. Most of the metabolic pathways induced in these fungicide-treated isolates were similar, indicating that benzovindiflupyr exhibited a conserved mechanism of SDHIs inhibiting Colletotrichum. At the same level of suppressive SDH activity, benzovindiflupyr activated more than three times greater gene numbers of Colletotrichum than boscalid, suggesting that benzovindiflupyr could activate distinct mechanisms against Colletotrichum. Membrane-related gene ontology terms, mainly including intrinsic components of membrane, were highly abundant for the benzovindiflupyr-treated isolates rather than boscalid-treated isolates. Only benzovindiflupyr increased the relative conductivities of hyphae, indicating that it could damage the cell membrane and increase mycelial electrolyte leakage. Thus, we proposed that the high bioactivity of benzovindiflupyr against Colletotrichum occurred by inhibiting SDH activity and damaging the cell membrane at the same time. The research improves our understanding the mode of action of SDHI fungicides against Colletotrichum.

Comprehensive Overview of Carboxamide Derivatives as Succinate Dehydrogenase Inhibitors

Up to now, a total of 24 succinate dehydrogenase inhibitors (SDHIs) fungicides have been commercialized, and SDHIs fungicides were also one of the most active fungicides developed in recent years. Carboxamide derivatives represented an important class of SDHIs with broad spectrum of antifungal activities. In this review, the development of carboxamide derivatives as SDHIs with great significances were summarized. In addition, the structure-activity relationships (SARs) of antifungal activities of carboxamide derivatives as SDHIs was also summarized based on the analysis of the structures of the commercial SDHIs and lead compounds. Moreover, the cause of resistance of SDHIs and some solutions were also introduced. Finally, the development trend of SDHIs fungicides was prospected. We hope this review will give a guide for the development of novel SDHIs fungicides in the future.

Activity of a SDHI fungicide penflufen and the characterization of natural-resistance in Fusarium fujikuroi

The occurrence of bakanae disease of rice caused by the fungus Fusarium fujikuroi in Zhejiang Province has become increasingly aggravated in recent years, concomitant with the development of resistance to the widely applied fungicides, prochloraz and phenamacril. In this study, the activity of a novel succinate dehydrogenase inhibitor (SDHI) fungicide, penflufen, against different fungi was evaluated in addition to the potential of penflufen in controlling F. fujikuroi infections. Penflufen exhibited good bioactivity against F. fujikuroi, but weak activity against Fusarium spp. and other investigated plant-pathogenic fungi including Colletotrichum spp. In addition to inhibiting mycelial growth, penflufen effectively inhibited F. fujikuroi conidium production. For germination, penflufen could effectively inhibit that of small conidia, but only delay the germination of large conidia. In addition, the sensitivity to penflufen among 100 F. fujikuroi isolates that were collected in areas that were never exposed to SDHIs was determined based on mycelium growth. Sensitivities surprisingly exhibited bimodal distributions, indicating the presence of natural resistance. Cross-resistance was not observed between penflufen in F. fujikuroi and two fungicides that have been extensively applied in field including prochloraz (a DMI) and phenamacril (a 2-cyanoacrylate fungicide), nor with the three SDHIs, fluopyram, benzovindiflupyr, and pydiflumetofen. Additional analysis identified five different point mutations in SDH-A (i.e., at residues 46, 225, 283, 430, and 586) of naturally resistant isolates. These results inform the potential application of the new SDHI fungicide penflufen for managing crop diseases and understanding possible resistance mechanisms among pathogens.

Design, Synthesis, Biological Evaluation, and Molecular Modeling of Novel 4H-Chromene Analogs as Potential Succinate Dehydrogenase Inhibitors

Thirty-one new 4H-chromene derivatives were designed and synthesized. Their structures were identified with IR, ¹H NMR, ¹³C NMR, and HRMS. The crystal structure of compound 2a was determined by single-crystal X-ray diffraction. Their antifungal activities were evaluated against Pyricularia oryzae, Erysiphe graminis, Coniella diplodiella, Pseudoperonospora cubensis, and Sclerotinia sclerotiorum. These results demonstrated that most compounds exhibited remarkable inhibitory activities at 20 μg/mL. Compounds 4b and 4c displayed excellent antifungal activity against S. sclerotiorum and possessed better efficacy than fluopyram. At the same time, the inhibitory activity of the bioactive compounds was evaluated against succinate dehydrogenase (SDH). The results showed that these compounds possessed outstanding activity. Compounds 4b and 4c displayed better inhibitory activity than fluopyram. The molecular modeling results revealed that compound 4c had stronger affinity to SDH than fluopyram. It is the first time that the inhibitory activity of 4H-chromene analogs against SDH has been reported.

A Method for the Examination of SDHI Fungicide Resistance Mechanisms in Phytopathogenic Fungi Using a Heterologous Expression System in Sclerotinia sclerotiorum

Succinate dehydrogenase inhibitors (SDHIs) are a class of broad-spectrum fungicides used for management of diseases caused by phytopathogenic fungi. In many cases, reduced sensitivity to SDHI fungicides has been correlated with point mutations in the SdhB and SdhC target genes that encode components of the succinate dehydrogenase complex. However, the genetic basis of SDHI fungicide resistance mechanisms has been functionally characterized in very few fungi. Sclerotinia sclerotiorum is a fast-growing and SDHI fungicide-sensitive phytopathogenic fungus that can be conveniently transformed. Given the high amino acid sequence similarity and putative structural similarity of SDHI protein target sites between S. sclerotiorum and other common phytopathogenic ascomycete fungi, we developed an in vitro heterologous expression system that used S. sclerotiorum as a reporter strain. With this system, we were able to demonstrate the function of mutant SdhB or SdhC alleles from several ascomycete fungi in conferring resistance to multiple SDHI fungicides. In total, we successfully validated the function of Sdh alleles that had been previously identified in field isolates of Botrytis cinerea, Blumeriella jaapii, and Clarireedia jacksonii (formerly S. homoeocarpa) in conferring resistance to boscalid, fluopyram, or fluxapyroxad and used site-directed mutagenesis to construct and phenotype a mutant allele that is not yet known to exist in Monilinia fructicola populations. We also examined the functions of these alleles in conferring cross-resistance to more recently introduced SDHIs including inpyrfluxam, pydiflumetofen, and pyraziflumid. The approach developed in this study can be widely applied to interrogate SDHI fungicide resistance mechanisms in other phytopathogenic ascomycetes.

Baseline sensitivity and action mechanism of the sterol demethylation inhibitor flusilazole to Valsa mali

The apple Valsa canker caused by Valsa mali is a devastating branch disease that has seriously threatened the development of the apple industry worldwide. In current study, a total of 115 V. mali strains collected from different apple orchards in Shaanxi Province of China during 2016 and 2017 were tested for their sensitivity to flusilazole. The average EC₅₀ (effective concentrations causing 50% mycelial growth inhibition) value of all tested strains for flusilazole was 0.0892 (±0.0036) μg/mL and the frequency distribution of the EC50 values was unimodal. Flusilazole exhibited both excellent protective and curative activity on detached apple branches, which was significantly better than the commonly used fungicide thiophanate-methyl. After flusilazole treatment, mycelia twisted with offshoot of top increased, the V. mali strains lost the ability of fruiting body production, and cell membrane permeability of the mycelia increased while ergosterol content and pectinase activity decreased. The expression of pectinase genes involved in virulence down-regulated after flusilazole treatment. This study is the first report on the baseline sensitivity of V. mali to flusilazole. These results indicated that flusilazole has a great potential to play an important role in the management of Valsa canker.

C=C-Ene-Reductases Reduce the C=N Bond of Oximes

Although enzymes have been found for many reactions, there are still transformations for which no enzyme is known. For instance, not a single defined enzyme has been described for the reduction of the C=N bond of an oxime, only whole organisms. Such an enzymatic reduction of an oxime may give access to (chiral) amines. By serendipity, we found that the oxime moiety adjacent to a ketone as well as an ester group can be reduced by ene-reductases (ERs) to an intermediate amino group. ERs are well-known enzymes for the reduction of activated alkenes, as of α,β-unsaturated ketones. For the specific substrate used here, the amine intermediate spontaneously reacts further to tetrasubstituted pyrazines. This reduction reaction represents an unexpected promiscuous activity of ERs expanding the toolkit of transformations using enzymes.

Molecular and Biochemical Characterization of Pydiflumetofen-Resistant Mutants of Didymella bryoniae

Gummy stem blight (GSB), caused by Didymella bryoniae, is a devastating disease on watermelon. Pydiflumetofen belongs to succinate dehydrogenase inhibitor (SDHI) fungicide, which is effective in controlling many plant diseases. The EC₅₀ values of 69 D. bryoniae isolates to pydiflumetofen ranged from 0.0018 to 0.0071 μg/mL, and the minimal inhibitory concentration (MIC) value of all strains to pydiflumetofen was <0.05 μg/mL. Eight pydiflumetofen-resistant mutants were obtained, and the level of resistance was stable. The mycelial growth, dry weight of mycelia, hyphal morphology, and pathogenicity of most resistant mutants did not change significantly compared with their parental strains, which indicated that the resistance risk of D. bryoniae to pydiflumetofen would be medium to high. Sequencing alignment showed that five resistant mutants presented a mutation at codon 277 (H277Y) in the SdhB gene. The point mutants FgSdhB^H248Y/R exhibited decreased sensitivity to pydiflumetofen in Fusarium graminearum, which indicated that the point mutants of SdhB could reduce sensitivity to pydiflumetofen. These results further increase our understanding about the mode of action and the resistance mechanism of pydiflumetofen.

Discovery of luotonin A analogues as potent fungicides and insecticides: Design, synthesis and biological evaluation inspired by natural alkaloid

The prevention and control of plant diseases and insect pests is the most crucial issue facing crop protection. To discover novel pesticide candidates with diverse chemical structures from natural products, a series of luotonin A analogues were designed, synthesized and evaluated for their antifungal and insecticidal activities. Most of these compounds exhibited potent activity against Botrytis cinerea, Magnaporthe oryzae and Aphis craccivora. Among them, the antifungal activity of compound 10s against B. cinerea was comparable to azoxystrobin (EC₅₀ = 0.09 mM) and against M. oryzae (EC₅₀ = 0.19 mM) was slightly weaker than that of azoxystrobin (EC₅₀ = 0.17 mM). Compounds 10k and 10o are the most active compounds against A. craccivora having identical mortality value of 42.05% at 50 μg/mL, respectively, which were slightly lower than pymetrozine (51.14%) at the same concentration. Revealed morphological changes of the fungal cell surface by scanning electron microscopy indicated that luotonin A analogues might exert their antifungal activity by destroying fungal cell membrane and cell wall. Furthermore, the results of the in vivo protective and curative activities of the compound 10s against S. sclerotiorum and B. cinerea showed that the curative effect was stronger than its protective effect and the curative effects reached 67.17% and 73.82% at 80 μg/mL respectively. The above results further demonstrated the potential of luotonin A analogues as novel fungicides and insecticides.

Synthesis and Biological Activity of Novel Succinate Dehydrogenase Inhibitor Derivatives as Potent Fungicide Candidates

In searching for novel fungicidal leads, the novel bioactive succinate dehydrogenase inhibitor (SDHI) derivatives were designed and synthesized by the inversion of carbonyl and amide groups. Bioassay indicated that compound 5i stood out with a broad spectrum of in vitro activity against five fungi. Its EC₅₀ value (0.73 μg/mL) was comparable to that of boscalid (EC₅₀ of 0.51 μg/mL) and fluxapyroxad (EC₅₀ of 0.19 μg/mL) against Sclerotinia sclerotiorum. For Rhizoctonia cerealis, 5i and 5p with EC₅₀ values of 4.61 and 6.48 μg/mL, respectively, showed significantly higher activity than fluxapyroxad with the EC₅₀ value of 16.99 μg/mL. In vivo fungicidal activity of 5i exhibited an excellent inhibitory rate (100%) against Puccinia sorghi at 50 μg/mL, while the positive control boscalid showed only a 70% inhibitory rate. Moreover, 5i showed promising fungicidal activity with a 60% inhibitory rate against Rhizoctonia solani at 1 μg/mL, which was better than that of boscalid (30%). Compound 5i possessed better in vivo efficacy against P. sorghi and R. solani than boscalid. Molecular docking showed that even the carbonyl oxygen atom of 5i was far from the pyrazole ring. It could also form hydrogen bonds toward the hydroxyl hydrogen and amino hydrogen of TYR58 and TRP173 on SDH, respectively, which consisted of the positive control fluxapyroxad. Fluorescence quenching analysis and SDH enzymatic inhibition studies also validated its mode of action. Our studies showed that 5i was worthy of further investigation as a promising fungicide candidate.

Antifungal activity of zedoary turmeric oil against Phytophthora capsici through damaging cell membrane

Phytophthora capsici is a plant oomycete pathogen, which causes many devastating diseases on a broad range of hosts. Zedoary turmeric oil (ZTO) is a kind of natural plant essential oil that has been widely used in pharmaceutical applications. However, the antifungal activity of ZTO against phytopathogens remains unknown. In this study, we found ZTO could inhibit P. capsici growth and development in vitro and in detached cucumber and Nicotiana benthamiana leaves. Besides, ZTO treatment resulted in severe damage to the cell membrane of P. capsici, leading to the leakage of intracellular contents. ZTO also induced a significant increase in relative conductivity, malondialdehyde concentration and glycerol content. Furthermore, we identified 50 volatile organic compounds from ZTO, and uncovered Curcumol, β-elemene, curdione and curcumenol with strong inhibitory activities against mycelial growth of P. capsici. Overall, our results not only shed new light on the antifungal mechanism of ZTO, but also imply a promising alternative for the control of phytophthora blight caused by P. capsici.

Antifungal Activity and Action Mechanism of the Natural Product Cinnamic Acid Against Sclerotinia sclerotiorum

Sclerotinia stem rot caused by Sclerotinia sclerotiorum (Lib.) de Bary spreads worldwide and causes serious economic losses. Considering the development of fungicide resistance and chemical residues, it is urgently necessary to explore alternative fungicides. In this study, the activity of the natural product cinnamic acid was assessed. The EC₅₀ values for cinnamic acid inhibition of mycelial growth of 103 S. sclerotiorum strains ranged from 9.37 to 42.54 µg/ml with an average EC₅₀ value of 18.77 (±3.39) µg/ml. No cross-resistance was detected between cinnamic acid and the commonly used fungicides carbendazim or dimethachlon. After treatment with cinnamic acid, mycelia distorted with more branches, no sclerotia developed, and the oxalic acid content decreased, whereas cell membrane permeability increased significantly. In pot experiments, cinnamic acid at 2,000 µg/ml provided over 95% efficacy against both carbendazim-sensitive and carbendazim-resistant strains of S. sclerotiorum. The expression of the sclerotia development-correlated genes Sac1, Pac1, Smk1, and Pka1 decreased, whereas the Cna1 gene expression increased. Altogether, cinnamic acid shows potential to be a natural alternative to commercial fungicides or a lead compound to develop new fungicides for the control of Sclerotinia stem rot. The biological characteristics contribute to the understanding of the action mechanism of cinnamic acid against S. sclerotiorum.

Fungicidal activity of 10-deacetylbacatin III against Phytophthora capsici via inhibiting lysine biosynthesis

10-deacetyl-bacatin III (10-DAB) is a natural plant-derived taxane diterpene, whose antimicrobial activity against phytopathogens remains unknown. In this study, we demonstrated the antimicrobial effect of 10-DAB on plant-pathogenic oomycetes. Our results revealed that 10-DAB exhibited significant antimicrobial activities against test oomycetes, especially against Phytophthora capsici, with a median effective concentration (EC₅₀) of 1.46 μg/mL, but had no effect on test fungi. Under 10-DAB treatment, mycelia of P. capsici were contorted with an increased number of top branches, and the production and germination of zoospores were inhibited and delayed, respectively. In addition, 10-DAB had favorable protective and curative activities with control efficacies of 63.90% and 74.81% at 200 μg/mL on detached pepper leaves. Furthermore, 10-DAB caused a significant decrease in soluble protein, lysine, and α, ε-diaminopimelic acid content of P. capsici, which suggested that 10-DAB inhibited the lysine biosynthesis. On the contrary, treatment with exogenous lysine effectively counteracted 10-DAB's inhibition activity on P. capsici. Moreover, relative expression of four key lysine biosynthesis-related genes of P. capsici were decreased upon 10-DAB treatment. Taken together, our findings suggest a lysine biosynthesis inhibiting-dependent antimicrobial activity of 10-DAB against P. capsici, which contributes to accelerating the application of 10-DAB for successful management of phytophthora blight disease in agricultural production.

Investigation of Novel Pesticides with Insecticidal and Antifungal Activities: Design, Synthesis and SAR Studies of Benzoylpyrimidinylurea Derivatives

In order to find pesticides with insecticidal and antifungal activities, a series of novel benzoyl pyrimidinylurea derivatives were designed and synthesized. All target compounds were identified by ¹H-NMR spectroscopy and HRMS. Insecticidal and antifungal activity of these compounds were evaluated and the structure-activity relationships (SAR) were clearly and comprehensively illustrated. Compound 7, with low toxicity to zebrafish (LC50 = 378.387 µg mL-1) showed 100% inhibition against mosquito (Culex pipiens pallens) at 0.25 µg mL-1. Both compounds 19 and 25 exhibited broad-spectrum fungicidal activity (>50% inhibitory activities against 13 phytopathogenic fungi), which were better than those of the commercial pesticide pyrimethanil (>50% inhibitory activities against eight phytopathogenic fungi). Furthermore, compounds 19 and 25 exhibited protective activity against Sclerotinia sclerotiorum on leaves of Brassica oleracea L. during in vivo experiments.

Effects of a novel SDHI fungicide pyraziflumid on the biology of the plant pathogenic fungi Bipolaris maydis

Pyraziflumid is a novel member of succinate dehydrogenase inhibitor (SDHI) fungicide. Southern corn leaf blight (SCLB) caused by Bipolaris maydis is an important foliar disease of maize crop. In this study, baseline sensitivity of B. maydis to pyraziflumid was determined using 100 strains of B. maydis collected from different geographical regions in Jiangsu Province of China during 2015 and 2016, and EC₅₀ values ranged from 0.0309 to 0.8856 μg/ml with the average value of 0.2780 ± 0.2012 μg/ml for mycelial growth, and 0.032 to 0.9592 μg/ml with the average value of 0.3492 ± 0.2450 μg/ml for conidium germination. After treatment with pyraziflumid, the distribution of cell nucleus and septum of mycelium was not changed, but hyphae of offshoot and conidia production decreased, cell secretion decreased, the cell membrane was damaged, mycelium electrolyte leakage increased, and organelles in mycelial cell dissolved and vacuolated. The protective and curative activity test of pyraziflumid suggested that pyraziflumid had great control efficiency against B. maydis on detached corn leaves. In protective activity assay with application of pyraziflumid at 5 μg/ml and 10 μg/ml, the control efficacy reached to 87.32% and 100% respectively. In curative activity assay with application of pyraziflumid at 20 μg/ml and 50 μg/ml, the control efficacy reached to 82.10% and 100% respectively.