Methyl Benzimidazole Research Articles

Visual detection of fungicide resistance by combining RPA and CRISPR/Cas12a in peach Brown rot fungus Monilinia fructicola.

Peach brown rot caused by Monilinia fructicola severely affects the quality and yield of peach, resulting in large economic losses worldwide. Methyl benzimidazole carbamate (MBC) fungicides and sterol demethylation inhibitor (DMI) fungicides are among the most applied chemical classes used to control the disease but resistance in the target pathogen has made them risky choices. Timely monitoring of resistance to these fungicides in orchards could prevent control failure in practice. In the current study, we developed methods based on recombinase polymerase amplification (RPA) and CRISPR/Cas12a systems to detect MBC and DMI resistance based on the E198A mutation in the β-tubulin (MfTub2) gene and the presence of the Mona element in the upstream region of the MfCYP51, respectively. For MBC resistance, RPA primers were designed that artificially incorporated PAM sites to facilitate the CRISPR/Cas12a reaction. Subsequently, specific tcrRNAs were designed based on the E198A mutation site. For the detection of the Mona element, we designed RPA primers M-DMI-F2/M-DMI-R1 that in combination with crRNA1 detected 'Mona' and distinguished resistant from sensitive strains. Both methods exhibited high sensitivity and specificity, requiring only a simple isothermal device to obtain results within 1 h at 37 °C. The FQ-reporter enabled visualization with a handheld UV or white light flashlight. This method was successfully used with purified DNA from lab cultures and crude DNA from symptomatic fruit tissue, highlighting its potential for on-site detection of resistant strains in orchards. © 2024 Society of Chemical Industry.

Profitability of foliar fungicides in double crop soybean under low-disease environments

Double-crop soybean production involves planting soybean (Glycine max) directly following winter wheat (Triticum aestivum) harvest. Frogeye leaf spot (FLS), caused by Cercospora sojina, is an important late-season foliar disease affecting soybean fields in the United States. In some instances, foliar fungicides have been used in double-crop soybean production with little to no FLS present, raising questions on the profitability of these applications. This study analyzed yield data from 25 fungicide trials across five states (Illinois, Indiana, Kentucky, Missouri, and Tennessee) conducted under low FLS pressure, from 2008 to 2021, on double-crop soybean. Fungicide classes evaluated in the trials included quinone outside inhibitors (QoI), demethylation inhibitors (DMI), and methyl benzimidazole carbamates (MBC) applied alone, and mixtures of chemistry classes that included DMI+succinate dehydrogenase inhibitor (SDHI), MBC+DMI, QoI+DMI, and QoI+DMI+SDHI. A network meta-analytic model estimated yield differences between fungicide-treated and nontreated plots, which ranged from -28 to 72 kg/ha among the fungicide treatments. Negative yield response values were estimated for the single fungicide classes MBC (-15.7 kg/ha) and QoI (-28.4 kg/ha). Yield difference as high as 72.8 kg/ha was estimated only for DMI+SDHI. Economic analyses indicated that, due to the lower yield responses, probabilities of breaking even were lower than 50% for all fungicide treatments, regardless of the fungicide cost or soybean sale price. Therefore, the low yield responses associated with foliar fungicides in low-disease environments linked to the higher risk of not offsetting the costs, suggest that growers should consider disease risk prior to making the fungicide application.

Comparative Fitness of Monilinia fructicola Isolates with Multiple Fungicide-Resistant Phenotypes.

This study characterized 52 isolates of Monilinia fructicola from peach and nectarine orchards for their multiresistance patterns to thiophanate-methyl (TF), tebuconazole (TEB), and azoxystrobin (AZO) using in vitro sensitivity assays and molecular analysis. The radial growth of M. fructicola isolates was measured on media amended with a single discriminatory dose of 1 μg/ml for TF and AZO and 0.3 μg/ml for TEB. Cyt b, CYP51, and β-tubulin were tested for point mutations that confer resistance to quinone outside inhibitors (QoIs), demethylation inhibitors (DMIs), and methyl benzimidazole carbamates (MBCs), respectively. Eight phenotypes were identified, including isolates with single, double, and triple in vitro resistance to QoI, MBC, and DMI fungicides. All resistant phenotypes to TF and TEB presented the H6Y mutation in β-tubulin and the G641S mutation in CYP51. None of the point mutations typically linked to QoI resistance were present in the Monilinia isolates examined. Moreover, fitness of the M. fructicola phenotypes was examined in vitro and in detached fruit assays. Phenotypes with single resistance displayed equal fitness in vitro and in fruit assays compared with the wild type. In contrast, the dual- and triple-resistance phenotypes suffered fitness penalties based on osmotic sensitivity and aggressiveness on peach fruit. In this study, multiple resistance to MBC, DMI, and QoI fungicide groups was confirmed in M. fructicola. Results suggest that Monilinia populations with multiple resistance phenotypes are likely to be less competitive in the field than those with single resistance, thereby impeding their establishment over time and facilitating disease management.

Effects of Fungicides on Fungal Development, Conidiophore Morphology, and Conidial Releases from Single Strawberry Powdery Mildew Colonies Assessed Using an Electrostatic Technique

We evaluated the effects of fungicides on strawberry powdery mildew (PM) fungus, Podosphaera aphanis, using an electrostatic technique. Thirty-six fungicides were sprayed on single colonies of P. aphanis on leaves of strawberry seedlings (Fragaria × ananassa Duchesne ex Rozier). Colony development varied depending on the tested fungicides. Particularly, pyraziflumid, triflumizole, triforine, polyoxin, sodium hydrogen carbonate + copper wettable powder, and flutianil + mepanipyrim were highly effective for reducing colony development. P. aphanis colonies were histochemically stained to observe the morphological characteristics of fungal cells forming normal and abnormal conidiophores. Abnormal conidiophores were classified into seven types based on their morphological and cytological characteristics. Finally, asexual conidia were collected from single P. aphanis colonies on the leaves spray-treated with fungicides using a dielectrically polarized insulator plate (electrostatic spore collector); conidia attracted to the insulator plates were counted using a high-fidelity digital microscope. Most tested fungicides highly inhibited the production and/or germination of asexual conidia. The germination of asexual conidia was observed only in thiophanate-methyl (methyl benzimidazole carbamates fungicides; MBC fungicides) and azoxystrobin (quinone outside inhibitors; QoI fungicides). Assessing with the electrostatic technique, we clarified that P. aphanis has developed resistance to both thiophanate-methyl and azoxystrobin. Thus, the methodological assessment analyzing the colony development and the number of conidia released from single colonies will be helpful information for screening effective fungicides.

Multiple resistance of Colletotrichum truncatum from soybean to QoI and MBC fungicides in Brazil

AbstractColletotrichum truncatum, the predominant fungal species associated with soybean anthracnose, is responsible for significant losses in this crop. Chemical control via fungicide application is the most effective strategy for the control of soybean foliar diseases. However, the increasing incidence of anthracnose in some regions of Brazil indicates that current chemical control is not effective against anthracnose. In this study, we evaluated the fungicide sensitivity of C. truncatum genetic lineages to the fungicides azoxystrobin, thiophanate‐methyl, difenoconazole, and fludioxonil using isolates representing two important regions of soybean production in Brazil. We characterized the molecular resistance to the quinone‐outside inhibitors (QoI), methyl benzimidazole carbamates (MBC), and demethylation inhibitor (DMI) fungicide groups based on amino acid sequences of the cytochrome b (cytb), β‐tubulin gene (β‐tub), and P450 sterol 14a‐demethylases (CYP51) genes. Multiple resistance of C. truncatum isolates to QoI and MBC was observed associated with mutation points in the β‐tub (E198A and F200Y) and cytb (G143A). Alternatively, low EC50 values were found for fludioxonil and difenoconazole indicating high efficacy. Analysis of C. truncatum genomes revealed two potential DMI targets, CYP51A and CYP51B, and higher genetic variability in the CYP51A gene. A positive correlation was found between genetic differentiation of C. truncatum populations and fungicide sensitivity (Student's t‐test <0.001). To our knowledge, this is the first report of multiple resistance to QoI and MBC fungicides in C. truncatum in Brazil.

Evaluation of foliar fungicides for frogeye leaf spot control and yield protection in soybean in Arkansas

The efficacy of fifteen foliar fungicides to control frogeye leaf spot (caused by Cercospora sojina K. Hara) and protect soybean grain yield was investigated over three years (2014–2016) in two field experiments. Experiments were divided into two fungicide groups: premix fungicides, which included combinations of quinone outside inhibitors (QoI), demethylation inhibitors (DMI), succinate dehydrogenase inhibitors (SDHI), or methyl benzimidazole carbamates (MBC), and solo fungicides, all DMI fungicides. Fungicides were applied once at the full pod (R4) in 2014 and 2015 and at the beginning seed (R5) growth stage in 2016. A very susceptible frogeye leaf spot cultivar, Armor 48R40, was used. Frogeye leaf spot severity at fungicide application timing average 1.0, 0.5, and 8.0% in 2014, 2015, and 2016, respectively. Final disease severity averaged 21.7, 14.5, and 15.1% in 2014, 2015, and 2016, respectively on the non-treated control. Azoxystrobin provided no disease control, suggesting the presence of QoI-resistant C. sojina. Three fungicides: azoxystrobin + difenoconazole, flutriafol, and thiophanate-methyl + tebuconazole applied at R4 provided effective disease control compared to the non-treated control. Fungicides applied at R5 provided no disease control. No fungicide provided significant grain yield protection in either experiment. Overall, the average yield protection trend by fungicides applied at R4 and R5 was 6.8 and 3.0%, respectively compared to the non-treated control. These data suggest that although foliar fungicides can provide effective frogeye leaf spot control, yield protection may be limited when applied at the R4 growth stage, particularly when disease severity exceeds 0.5% on a very susceptible soybean cultivar.

Low frequency of resistance to thiophanate-methyl in Monilinia fructicola populations from southeastern United States peach orchards

Methyl benzimidazole carbamate (MBC) fungicides were once widely used for brown rot (Monilinia fructicola) control of peach (Prunus persica (L.) Batsch) in the southeastern US, but their use was substantially reduced and often eliminated due to widespread resistance. In this study, 233 M. fructicola isolates were collected from major peach production areas in Alabama, Georgia, and South Carolina, and sensitivity to thiophanate-methyl was examined. Isolates were also collected from one organic and two experimental peach orchards. A discriminatory dose of 1 μg/ml was used to distinguish sensitive (S) and moderately sensitive (S-LR) isolates from low resistant phenotypes, while 50 and 500 μg/ml thiophanate-methyl concentrations were used to determine high resistant (HR) phenotypes. Sequence analyses were performed to identify mutations in the β-tubulin target gene and detached fruit assays were performed to determine the efficacy of a commercial product against isolates representing each phenotype. Results indicated 55.7%, 63.5%, and 75.9% of isolates from Alabama, Georgia, and South Carolina, respectively, were S to thiophanate-methyl; 44.3%, 36.5%, and 21.4% were S-LR; no isolates were LR; and only 3 isolates (1.3%) from South Carolina were HR. No mutations in S or S-LR isolates were found, but HR isolates revealed the E198A mutation, an amino acid change of glutamic acid to alanine conferring high resistance. The high label rate of a commercial product containing thiophanate-methyl controlled brown rot caused by S and S-LR isolates in detached fruit studies but was ineffective against HR isolates. The combinations of thiophanate-methyl with azoxystrobin or isofetamid, when mixed together and applied in an experimental orchard 14 days preharvest, significantly reduced brown rot incidence on pre and postharvest commercially ripe fruit and efficacy was comparable to that of a grower standard fungicide. These results indicate that thiophanate-methyl may again be useful to peach growers in the southeastern US for brown rot and fungicide resistance management.

Classification and mode of action of chemical fungicides applied for cereal crops protection in Belarus

Cultivated area of cereal crops in Belarus is up to 35 %. As many as 61 seed dressers and 100 fungicides are used for protection of cereals against a number of diseases in the country. Eleven chemical groups of fungicides are exploited in Belarus: phenylamides, methyl benzimidazole carbamates, aryl-phenyl-ketones, SDHI, QoI, anilino-pyrimidines, azanaphthalenes, phenylpyrroles, DMI, amines (morpholines), dithiocarbamates. Their classification and modes of actions are the clue to choose suitable active ingredients according to the current phytopathological situation, weather conditions etc. Classification of fungicides is given based upon chemical structure, target sites, mobility within the plants and action on fungal development inside the plant tissue.

Discovery and SAR Studies of Potent Modulators of BMI‐1 Expression

AbstractIn our efforts to identify molecules that selectively reduce the expression of BMI1, a stem cell gene, we discovered and characterized the first‐in‐class series of small molecules that modulate the expression of BMI1 protein in cancer cells. Structure–activity and structure–property relationships associated with this series were investigated through medicinal chemistry efforts. These studies revealed important structural features required for achieving anti‐tumor activity and acceptable pharmacokinetic properties within this series. The 4‐CF3−Ph at the left‐side of the molecule, a proper placement of the N‐atom on the six‐membered heterocycle in the middle, combined with a properly substituted C(2)‐methyl benzimidazole on the right‐hand side were required to achieve potency, microsomal stability, and exposure upon oral dosing. A compound (PTC‐02) with acceptable pharmacological properties and efficacious in vivo in several tumor animal models was identified.

Synthesis and Antioxidant Studies of 2,4-Dioxothiazolidine-5-acetic Acid Based Organic Salts: SC-XRD and DFT Approach.

In the current study, two organic salts (1 and 2) are synthesized, and then crystalline structures are characterized by FTIR, UV spectroscopy, and X-ray crystallographic studies. The organic salts 1 and 2 are optimized at the M06/6-311G(d,p)level of theory and further utilized for analysis of natural bond orbitals (NBOs), natural population, frontier molecular orbitals (FMOs), and global reactivity parameters, which confirmed the stability of the studied compounds and charge transfer phenomenon in the studied compounds. The studies further revealed that 1 and 2 are more stable than 3. The lowest energy merged monomer-coformer conformations were docked as flexible ligands with rigid fungal proteins and DNA receptors. The stagnant binding of the monomer through two H bonds with protein was observed for ligands 1 and 3 while different pattern was found with 2. The coformers formed a single H bond with the active site in 2 and 3 and a single pi-arene H interaction in 1. The two-point ligand-receptor interactions hooked the monomer between DNA base pairs for partial intercalation; pi stacking with additive hydrogen bonding with the base pair led to a strong benzimidazole interaction in 1 and 2, whereas ethylene diamine formed weak H bonding. Thus, the molecular docking predicted that the coformer exhibited DNA intercalation reinforced by its salt formation with benzimidazole 1 and methyl benzimidazole 2. Antioxidant studies depicted that 3 has a higher IC50 value than that of 2,4-D and also the largest value among the studied compounds, whereas 2 showed the lowest value among the studied compounds.

Efficacy of Single- and Multi-Site Fungicides Against Neopestalotiopsis spp. of Strawberry.

Recently, the Florida strawberry industry faced unprecedented outbreaks of an emerging disease caused by the fungus Neopestalotipsis spp. Currently, there are no fungicides labeled to control this disease in the U.S. and the efficacy of single- and multi-site fungicides is unknown. Therefore, this study aimed to determine the in vitro sensitivity of Neopestalotiopsis spp. isolates to fungicides with different modes of action and to evaluate the efficacy of these products on detached fruit and in the field. In preliminary in vitro tests, 30 commercially available fungicides were screened using discriminatory doses. The effective concentration that inhibited mycelial growth by 50% (EC50) was determined for the most effective single-site fungicides. Four field experiments were conducted during the 2019-20, 2020-21, and 2021-22 seasons to determine product efficacy in managing the disease. The single-site fungicides fludioxonil, fluazinam, the sterol de-methylation inhibitors (DMIs), and the multi-sites captan, thiram, and chlorothalonil were the most effective in inhibiting pathogen growth and suppressing disease development. Conversely, products in FRAC groups 1 (MBC) and 7 (SDHI), except for benzovindiflupyr, were not effective against Neopestalotiopsis spp. Resistance to fungicides from FRAC group 11, e.g., azoxystrobin, was confirmed by the presence of the G143A mutation in the cytochrome b gene together with inoculation tests and field trials. Our results provide information to support or discourage the registration of fungicides to manage Neopestalotiopsis fruit rot and leaf spot in strawberry production. .

In English

This study determined the corrosion inhibition levels of benzimidazole (BIA), 1-hydroxybenzotriazole (HBT), methylbenzimidazole (MBI) and 4-phenylimidazole (PIZ). By using simulation, it was possible to have a complete relationship with the experimental work because the results were completely consistent. Density functional theory (DFT) and Monte Carlo simulations were used to calculate several quantum chemical parameters. The molecules are simulated using quantum chemical calculations with Gaussian09 software. Fundamental factors determining the corrosion order of molecules are the highest-energy occupied and lowest-energy unoccupied molecular orbitals (HOMO and LUMO), frontier molecular orbital energy, back donating energy, electrophilicity, nucleophilicity, energy gap ∆E, absolute electronegativity (χ), softness, the number of electrons (∆N) transferred from inhibitors to iron, the dipole moment (μ), the global hardness (η) and the total energy.

Analysis of the binding modes and resistance mechanism of four methyl benzimidazole carbamates inhibitors fungicides with Monilinia fructicola β2-tubulin protein

Monilinia fructicola can infest plants during fruit flowering and during fruit storage and transportation, causing serious economic losses. The resistance problem of methyl benzimidazole carbamates inhibitors fungicide is becoming more and more prominent as the use time increases. By exploring the molecular binding mode, we studied the changes of the binding mode of the main amino acid residues between the four MBCs fungicides and the wild type and mutant Monilinia fructicoloa beta-tubulin protein constructed by homologous modeling. Constructing homology related models through sequence alignment based on sequence information from Monilinia fructicola beta-tubulin protein. Molecular docking and molecular dynamics simulations were then used to identify the optimum binding mode of benomyl, carbendazim, thiabendazole and thiophanate-methyl with Monilinia fructicola beta-tubulin protein. Furthermore, we calculated the binding free energy of four wild-type and mutant protein-ligand complexes using MM/PBSA. The result shows that when E198A was mutated, the hydrogen bonding force of thiophanate-methyl binding to the protein was reduced. The possible underlying cause of the resistance is the disappearance of the π-π stacking interaction with Phe200. When E198Q was mutated, all three fungicides, excluding carbendazim, interacted with Gln198 of the protein through hydrogen bonding. However, the binding pattern of carbendazim, thiophanate-methyl were least affected. When F200Y was mutated, the binding pocket of benomyl is slightly altered concerning the binding pattern between the wild-type protein and the fungicide concerning the amino acid residues. The resistance mechanism of M. fructicola beta-tubulin protein to MBCs fungicides and the mechanism of cross-resistance between MBCs fungicides were initially elucidated by computer simulation.

Transition metal (II) complexes with 2- amino methyl benzimidazole derived schiff base: synthesis, characterization and biological activity

Novel transition metal [Co(ll), Cu(ll), Ni(ll) and VO(ll)] complexes derived from Schiff bases of 2-amino methyl benzimidazole and 2-furan carbaldehyde(BNFM) have been synthesized and characterized by physical, spectral and analytical data. The synthesized Schiff-bases act as tridentate ligand for the complexation reaction with Co (ll),Cu(II), Ni(ll) and VO(ll) ions. The new compounds, possessing the general formula [ML2] where [M=Co (II), Cu (II), Ni(II) and VO(ll)]. The Schiff bases and their complexes have been screened for biological activity against the strains such as Escherichia coli, Staphylococcus aureus, B.Subtilis and Pseudomonas aeruginosa in order to evaluate the effect of complexation of metals with Schiff base. The metal coordinated Schiff bases have shown more antibacterial activity against bacterial species as compared to uncoordinated Schiff-bases.

Prevalence of Carbendazin Resistance in Field Populations of the Rice False Smut Pathogen Ustilaginoidea virens from Jiangsu, China, Molecular Mechanisms, and Fitness Stability.

Rice false smut (RFS), caused by Ustilaginoidea virens, is an important fungal disease of rice. In China, Methyl Benzimidazole Carbamates (MBCs), including carbendazim, are common fungicides used to control RFS and other rice diseases. In this study, resistance of U. virens to carbendazim was monitored for three consecutive years during 2018 to 2020. A total of 321 U. virens isolates collected from Jiangsu Province of China were tested for their sensitivity to carbendazim on PSA. The concentration at which mycelial growth is inhibited by 50% (EC50) of the carbendazim-sensitive isolates was 0.11 to 1.38 µg/mL, with a mean EC50 value of 0.66 μg/mL. High level of resistance to carbendazim was detected in 14 out of 321 isolates. The resistance was stable but associated with a fitness penalty. There was a statistically significant and moderate negative correlation (r= -0.74, p < 0.001) in sensitivity between carbendazim and diethofencarb. Analysis of the U. virens genome revealed two potential MBC targets, Uvβ1Tub and Uvβ2Tub, that putatively encode β-tubulin gene. The two β-tubulin genes in U. virens share 78% amino acid sequence identity, but their function in MBC sensitivity has been unclear. Both genes were identified and sequenced from U. virens sensitive and resistant isolates. It is known that mutations in the β2-tubulin gene have been shown to confer resistance to carbendazim in other fungi. However, no mutation was found in the Uvβ2Tub gene in either resistant or sensitive isolates. Variations including point mutations, non-sense mutations, codon mutations, and frameshift mutations were found in the Uvβ1Tub gene from the 14 carbendazim-resistant isolates, which have not been reported in other fungi before. Thus, these results indicated that variations of Uvβ1Tub result in the resistance to carbendazim in field isolates of Ustilaginoidea virens.

Benzimidazole-Resistant Isolates with E198A/V/K Mutations in the β-Tubulin Gene Possess Different Fitness and Competitive Ability in Botrytis cinerea.

Previous studies in Botrytis cinerea showed that resistance to methyl benzimidazole carbamates (MBCs) was mainly related to E198A/V/K and F200Y mutations of the β-tubulin gene, and E198V was the dominant mutation in the resistant subpopulation in Hubei Province of China, indicating that resistant mutations might influence fitness. However, little is known about the effect of each E198A/V/K mutation on fitness. In this study, the fitness and competitive ability of isolates with E198A/V/K mutations were investigated. Results showed that E198A/V/K isolates and wild-type isolates shared similar fitness components in terms of virulence, sporulation, conidial germination, oxidative sensitivity, and sclerotial production and viability. However, slower mycelial growth at 4°C, higher sensitivity to 4% NaCl, and increased sclerotial production percentage at 4°C were observed in the isolates with E198V, E198K, and E198A mutations, respectively. Competitive analysis showed that the wild-type subpopulation became dominant after three disease cycles in the absence of fungicide selection pressure, whereas the resistant subpopulation seized the space of the sensitive subpopulation upon MBC application. Unexpectedly, the frequency of E198V isolates decreased dramatically after the first disease cycle with or without fungicide selection pressure. These results suggest that MBC-resistant isolates suffer little fitness penalty but possess competitive disadvantages in the absence of fungicide selection pressure. Under fungicide selection pressure, E198V isolates could not compete with E198A/K isolates. According to the current results, there is a great possibility that the E198V mutation will lose dominance in the future in China.

Synthesis and characterization of metal complexes of 2-(5-substituted-(Thiadiazolyl/Triazolyl)-2-thio) methyl benzimidazole

Co(ll). Ni(l). Cu(l) and Zn (II) complexes of 2-(4’-amino-(5'-(nicotinyl-4-phenyl-1',2',4-triazolyl-3’- thiomethvlbenzimidazole(L1 ). 2-((5'-(nicotinyl-4-phenyl-1',2',4-triazolyl-3'- thio) methyl benzimidazole (L2 ) and 2-(5'-(nicotinoyl)- 1'3'4'-thiadiazolyl-2'-thio) methyl benzimidazole) (L3 ) have been prepared and characterized.

Prevalence of H6Y mutation in β-tubulin causing thiophanate-methyl resistant in Monilinia fructicola from Fujian, China

Brown rot disease broke out in stone fruit orchards of Fujian, China in 2019, despite pre-harvest application of methyl benzimidazole carbamate (MBC). To determine the reason, a total of 44 Monilinia fructicola strains were collected from nectarine, plum and peach fruits in this study, among which 79.5% strains were resistant to thiophanate-methyl, indicated by discriminatory dose of 5 μg/mL. The resistance of these strains was confirmed by treating detached peach fruit with label rates of formulated thiophanate-methyl which only completely inhibit infection of the sensitive strains, but not the resistant strains. Further analysis of the mechanism of MBC resistance revealed that all resistant strains carry a H6Y mutation in β-tubulin protein Tub2, which was only reported previously in the M. fructicola strains from California, USA, and do not display obvious fitness penalties, as no significant defects in mycelial growth rate, sporulation, conidia germination, aggressiveness on detached peach fruit and temperature sensitivity was detected. In addition, we found that diethofencarb, the agent for managing MBC-resistance strains, was unable to inhibit growth of the H6Y strains. Taken together, our study, for the first time, identified a mutation form of H6Y in the β-tubulin protein of M. fructicola in China, rendering the strains wide resistance to thiophanate-methyl. This mechanism of M. fructicola gaining resistance to MBC fungicides needs to be fully considered, when designing management strategies to control brown rot disease in stone fruit orchards.

Baseline sensitivity and control efficacy of a new QiI fungicide, florylpicoxamid, against Botrytis cinerea.

Gray mold caused by Botrytis cinerea is an airborne plant pathogen with a necrotrophic lifestyle that infects more than 200 crops worldwide. Florylpicoxamid is a second-generation picolinamide fungicide inspired by a natural product. Florylpicoxamid targets the Qi site of the mitochondrial cytochrome bc1 complex and is currently being registered in China for the control of gray mold in a variety of crops. Although a broad spectrum of activity and attributes have been reported for florylpicoxamid, little is known about its effectiveness against gray mold or its protective and curative properties. Florylpicoxamid exhibited substantial inhibitory activity against 12 tested species of plant-pathogenic fungi, with effective concentration for 50% growth inhibition (EC50 ) values ranging from 0.017 to 2.096 μg ml-1 . A total of 129 isolates of B. cinerea from ten regions were tested for their sensitivity to florylpicoxamid, and the mean EC50 value was 0.04 ± 0.017 μg ml-1 . Furthermore, florylpicoxamid was observed to substantially inhibit all developmental stages of B. cinerea, with mycelial development, sclerotium germination, germ tube elongation and conidial germination being restrained with an EC50 value of 0.051 ± 0.0072, 0.012 ± 0.0069, 0.019 ± 0.0041 and 0.0062 ± 0.0007 μg ml-1 , respectively. No cross-resistance was observed between florylpicoxamid and quinone outside inhibitor (QoI), methyl benzimidazole carbamates or succinate dehydrogenase inhibitor. Florylpicoxamid also exhibited protective and curative activity against the development of B. cinerea infection in tests on tomato fruits. At application rates of 90, 112.5 and 135 g a.i. ha-1 , florylpicoxamid was also observed to provide more-effective control than boscalid (300 g a.i. ha-1 ). This study demonstrated that the novel fungicide florylpicoxamid exhibits strong inhibitory activity against B. cinerea, regardless of the resistance profiles of those isolates to tested fungicides with different modes of action. This makes florylpicoxamid a powerful new solution to optimize gray mold control and manage fungicide resistance. © 2022 Society of Chemical Industry.

Cucumber target spot control and Corynespora cassiicola inhibition by uni-and multi-site fungicides

Target spot, caused by Corynespora cassiicola, is among the main disease that may reduce cucumber yield in worldwide. However, few target spot control strategies have been evaluated. The study aimed to evaluate the effect of fungicides in controlling C. cassiicola in vitro and cucumber target spot in a greenhouse. The effect of seven and thirteen fungicides in conidial germination and mycelial growth, respectively, of three pathogen isolates was evaluated in culture medium. The most efficient fungicides in vitro were applied on cucumber plants, at the recommended commercial dose. After three or seven days of the preventive treatment, plants were sprayed with suspensions of the pathogen (104 conidia/mL). For the curative treatment, plants were inoculated 24 h before receiving the fungicide. Evaluation included target spot severity, number and diameter of lesions and sporulation on the leaf. Fungicides of the groups Methyl Benzimidazole Carbamates (MBC) and Quinone outside Inhibitors (QoI) were inefficient (EC50 > 100 μg/mL) in inhibiting the pathogen in vitro. Chlorothalonil, metiram, boscalid, difenoconazole, epoxiconazole, tebuconazole, and flutriafol showed EC50 < 1 or 1–10 μg/mL. Chlorothalonil, metiram + pyraclostrobin, boscalid + kresoxim-methyl, and azoxystrobin + benzovindiflupyr controlled the disease, providing greater severity reduction as preventive treatment, without any difference between the two application times. The number and diameter of lesions decreased when fungicides were applied as preventive treatment. Chlorothalonil reduced the number of lesions in curative treatment, while fluxapyroxad + pyraclostrobin, azoxystrobin + benzovindiflupyr, boscalid + kresoxim-methyl, and difenoconazole decreased the diameter of lesions. Sporulation on the leaves also reduced, especially when fungicides were preventively employed. A preventive management is recommended in areas with frequent reports of target spot outbreaks, adopting the alternation of the four most efficient fungicides in controlling the disease in order to reduce possible emergence of resistant isolates of the pathogen to the site-specific fungicides boscalid and benzovindiflupyr.