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Sweetpotato is an important crop whose roots are consumed by people worldwide. Meloidogyne enterolobii stands out as a highly deleterious variant among the species of root-knot nematode that causes significant damage in sweetpotato. In the present study, the activity of four nematicides against M. enterolobii was assessed both in vitro and in growth cabinet experiments. After 48 hours of exposure, fluopyram and cyclobutrifluram had a greater negative effect on the motility of M. enterolobii second-stage juveniles (J2s) compared to fluensulfone and hymexazol, with respective median effective concentration (EC50) values of 0.204, 0.423, 22.335 and 216.622 mg L-1. When M. enterolobii eggs were incubated for 72 hours at the highest concentration of each nematicides, the inhibitory hatching effect of cyclobutrifluram (2.5 mg L-1), fluopyram (1.25 mg L-1) and fluensulfone (80 mg L-1) surpassed 85%, whereas hymexazol (640 mg L-1) was only 67%. Similar results were observed in growth cabinet experiments as well. The disease index (DI) and gall index (GI) were significantly decreased by all four nematicides compared to the control. However, the application of hymexazol did not yield a statistically significant difference in the egg masses index compared to the control, a finding which may be attributed to its potentially limited penetrability through the eggshell barrier. Overall, this study has demonstrated that all four nematicides effectively suppress M. enterolobii in sweetpotato, and this is the first report on the nematicidal activity of cyclobutrifluram and hymexazol against M. enterolobii.

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Pythium sensu lato (s.l.) is a pathogenic oomycete. The present study was conducted to isolate and identify Pythium s.l. species associated with the rhizosphere and roots of greenhouse-growing cucumbers showing damping-off symptoms in 10 Omani governorates (provinces). A total of 166 isolates were recovered from 276 rhizosphere soil and root samples and were identified based on the ribosomal DNA (rDNA) internal transcribed spacer (ITS) region and the cytochrome c oxidase subunit I (COX I) gene region. Pythium aphanidermatum, P. myriotylum, Globisporangium spinosum, Globisporangium sp.1 (isolates Kb003/PySyCu-1 and Kb004/PySyCu-2), and Globisporangium sp.2 (isolate Ib002R) were identified. Among these species, P. aphanidermatum was the most abundant species, represented by 143 isolates (86.1%), followed by G. spinosum with 18 isolates (10.8%), Globisporangium sp.1 and P. myriotylum each with 2 isolates (2.4%), and Globisporangium sp.2 with 1 isolate (0.6%). Pathogenicity tests were also conducted for 38 isolates, including P. aphanidermatum (25), P. myriotylum (2), Globisporangium sp.2 (1), G. spinosum (8), and Globisporangium sp.1 (2). Among the tested isolates, only Globisporangium sp.2 isolate was avirulent, and none of the seeds were rotted at the end of the treatment. However, the other species induced the symptoms of seed decay with the incidence ranged from 86.7 to 100%. Phylogenetic analyses were conducted based on 222 ITS and 53 COX I sequences, and confirmed morphological identification. In addition, the genetic diversity of 93 P. aphanidermatum isolates was assessed via the amplified fragment length polymorphism (AFLP) method. The analysis produced 93 genotypes and 449 polymorphic loci. Pythium aphanidermatum populations were found to have moderate levels of genetic diversity (H = 0.2) and a moderate Shannon information index (I = 0.3793). Analysis of molecular variance (FST = 0.1, P = 0.0) revealed a moderate level of genetic differentiation among P. aphanidermatum isolates between Oman governorates. The sensitivity of 15 P. aphanidermatum isolates was evaluated against hymexazol at different concentrations (10, 100, and 1000 ppm). The results revealed that P. aphanidermatum could grow well at concentrations of up to 100 ppm hymexazol. However, hymexazol at 1000 ppm retarded the growth of P. aphanidermatum. This study showed that P. aphanidermatum is the most prevalent species in greenhouses in Oman and exhibited a moderate level of genetic diversity. Most of the isolates exhibited differences in tolerance to hymexazol but showed no resistance.

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In this study, starch (S) was gelatinized and carbonized to prepare carbonized/gelatinized S (CGS) as the research material. Then, peat extract (Pe) and surfactants with different ratios were single- and multi-modified on CGS, respectively, to prepare Pe-modified CGS (Pe-CGS) and multi-modified CGS, respectively. The microscopic morphology of multi-modified CGS was studied using various testing methods. The de-risking effect on Cd(II) and hymexazol in wastewater was investigated, and the effects of temperature, pH, and ionic strength were compared. The spheroidal structure of S was destroyed after carbonization, and Pe and surfactants were modified on the surface and changed the surface properties of CGS. The adsorption processes of Cd(II) and hymexazol were suitable to be described by the Langmuir and Freundlich models, respectively. The maximum adsorption capacities (qm) of Cd(II) and adsorption capacity parameter (k) of hymexazol on different modified CGSs presented the peak value at BS/Pe-CGS. With the increase in the modification ratio of Pe, BS, and SDS, qm and k increased, which showed a high value at 100 % modification. Increases in temperature and pH were beneficial to Cd(II) adsorption but were not conducive to hymexazol adsorption. The adsorption amount decreased for Cd(II) and increased first and then reduced for hymexazol with the rise in ionic strength. The adsorption process exhibited spontaneity, endothermic behavior for Cd(II), exothermic behavior for hymexazol, and an entropy-increasing reaction. The adsorption amount of Cd(II) and hymexazol by multi-modified CGS maintained approximately 81 % of the original sample after three rounds of regeneration.

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Fungicides are used worldwide to improve crop yields, but they can affect non-target soil microorganisms which are essential for ecosystem functioning. Microorganisms form complex communities characterized by a myriad of interspecies interactions, yet it remains unclear to what extent non-target microorganisms are indirectly affected by fungicides through biotic interactions with sensitive taxa. To quantify such indirect effects, we fragmented a soil microbial community by filtration to alter biotic interactions and compared the effect of the fungicide hymexazol between fractions in soil microcosms. We postulated that OTUs which are indirectly affected would exhibit a different response to the fungicide across the fragmented communities. We found that hymexazol primarily affected bacterial and fungal communities through indirect effects, which were responsible for more than 75% of the shifts in relative abundance of the dominant microbial OTUs after exposure to an agronomic dose of hymexazol. However, these indirect effects decreased for the bacterial community when hymexazol doses increased. Our results also suggest that N-cycling processes such as ammonia oxidation can be impacted indirectly by fungicide application. This work sheds light on the indirect impact of fungicide exposure on soil microorganisms through biotic interactions, which underscores the need for higher-tier risk assessment. ENVIRONMENTAL IMPLICATION: In this study, we used a novel approach based on the fragmentation of the soil microbial community to determine to which extent fungicide application could indirectly affect fungi and bacteria through biotic interactions. To assess off-target effects of fungicide on soil microorganisms, we selected hymexazol, which is used worldwide to control a variety of fungal plant pathogens, and exposed arable soil to the recommended field rate, as well as to higher rates. Our findings show that at least 75% of hymexazol-impacted microbial OTUs were indirectly affected, therefore emphasizing the importance of tiered risk assessment.

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Houttuynia cordata is a prevalent vegetable in several Asian countries and is commonly used as a traditional Chinese medicinal herb for treating various diseases in China. Unfortunately, its yield and quality are adversely affected by root rot. However, the pathogen responsible for the losses remains unidentified, and effective fungicides for its management have not been thoroughly explored. In this work, we demonstrate the first report of Globisporangium spinosum as the causative agent causing root rot of H. cordata. Moreover, we evaluated the efficacy of hymexazol to manage the disease, which displayed remarkable inhibitory effects against mycelial growth of G. spinosum in vitro, with EC50 values as low as 1.336 µg/ml. Furthermore, hymexazol completely inhibited sporangia in G. spinosum at a concentration of 0.3125 µg/ml. Specifically, we observed that hymexazol was highly efficacious in reducing the incidence of H. cordata root rot caused by G. spinosum in a greenhouse setting. These findings offer a potential management tool for utilization of hymexazol in controlling H. cordata root rot in field production.

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Hymexazol is a volatile fungicide widely used in agriculture, causing its abundance in the atmosphere; thus, its atmospheric fate and conversion are of great importance when assessing its environmental impacts. Herein, we report a theoretical kinetic mechanism for the oxidation of hymexazol by OH radicals, as well as the subsequent reactions of its main products with O2 and then with NO by using the Rice-Ramsperger-Kassel-Marcus-based Master equation kinetic model on the potential energy surface explored at the ROCBS-QB3//M06-2X/aug-cc-pVTZ level. The predicted total rate constants ktotal(T, P) for the reaction between hymexazol and OH radicals show excellent agreement with scarcely available experimental values (e.g., 3.6 × 10-12 vs (4.4 ± 0.8) × 10-12 cm3/molecule/s at T = 300 K and P = 760 Torr); thus, the calculated kinetic parameters can be confidently used for modeling/simulation of N-heterocycle-related applications under atmospheric and even combustion conditions. The model shows that 3,4-dihydroxy-5-methyl-4,5-dihydro-1,2-oxazol-5-yl (IM2), 3,5-dihydroxy-5-methyl-4,5-dihydro-1,2-oxazol-4-yl (IM3), and (3-hydroxy-1,2-oxazol-5-yl)methyl (P8) are the main primary intermediates, which form the main secondary species of (3,4-dihydroxy-5-methyl-4,5-dihydro-1,2-oxazol-5-yl)dioxidanyl (IM4), (3,5-dihydroxy-5-methyl-4,5-dihydro-1,2-oxazol-4-yl)dioxidanyl (IM7), and ([(3-hydroxy-1,2-oxazol-5-yl)methyl]dioxidanyl (IM11), respectively, through the reactions with O2. The main secondary species then can react with NO to form the main tertiary species, namely, (3,4-dihydroxy-5-methyl-4,5-dihydro-1,2-oxazol-5-yl)oxidanyl (P19), (3,5-dihydroxy-5-methyl-4,5-dihydro-1,2-oxazol-4-yl)oxidanyl (P21), and [(3-hydroxy-1,2-oxazol-5-yl)methyl]oxidanyl (P23), respectively, together with NO2. Besides, hymexazol could be a persistent organic pollutant in the troposphere due to its calculated half-life τ1/2 of 13.7-68.1 h, depending on the altitude.

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BACKGROUND: Grapes are highly vulnerable to infection by carbon black aspergilli, which produce ochratoxin A (OTA), a mycotoxin. Carbendazim and hymexazol are widely applied to control grape diseases. Howerver, fungicides, toxigenic fungi, and OTA can be transferred from grapes to wine causing potential safety issues. The impact of these residues on fungal populations and OTA during vinification are currently unclear. Here we investigated the effects of carbendazim and hymexazol on the viability of Aspergillus carbonarius and OTA contamination during an indoor wine-processing experiment. RESULTS: The population size of A. carbonarius substantially increased at 24 h followed by a significantly decreased at 72 h after destemming and crushing. However, carbendazim and hymexazol notably inhibited the growth of A. carbonarius in must samples. In addition, yeast growth was substantially deleyed by carbendazim, hymexazol, and OTA during the first 3 days in compared with the control. Carbendazim, hymexazol, and OTA residues declined over time, and the processing factors (PFs) for carbendazim and hymexazol throughout vinification were 0.164, 0.074, and 0.185-0.476, respectively. Carbendazim and hymexazol each reduced OTA concentrations. However, there was no significant difference after 48 h. Addition of carbendazim or hymexazol significantly reduced the level of A. carbonarius but had no significant effect on the final concentration of OTA in mature wine. CONCLUSION: The wine-making process can reduce the residues of OTA, carbendazim, and hymexazol in grapes, but it is recommended that grapes chosen to make wine should be free of A. carbonarius contamination. © 2023 Society of Chemical Industry.

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Agents with antifungal activity play a vital role as therapeutics in health care, as do fungicides in agriculture. Effectiveness, toxicological profile, and eco-friendliness are among the properties used to select suitable substances. Furthermore, a steady supply of new agents with different modes of action is required to counter the well-known potential of human and phyto-pathogenic fungi to develop resistance against established antifungals. Here, we use an in vitro growth assay to investigate the activity of the calcineurin inhibitor tacrolimus in combination with the commercial fungicides cyproconazole and hymexazol, as well as with two earlier reported novel {2-(3-R-1H-1,2,4-triazol-5-yl)phenyl}amines, against the fungi Aspergillus niger, Colletotrichum higginsianum, Fusarium oxysporum and the oomycete Phytophthora infestans, which are notoriously harmful in agriculture. When tacrolimus was added in a concentration range from 0.25 to 25 mg/L to the tested antifungals (at a fixed concentration of 25 or 50 mg/L), the inhibitory activities were distinctly enhanced. Molecular docking calculations revealed triazole derivative 5, (2-(3-adamantan-1-yl)-1H-1,2,4-triazol-5-yl)-4-chloroaniline), as a potent inhibitor of chitin deacetylases (CDA) of Aspergillus nidulans and A. niger (AnCDA and AngCDA, respectively), which was stronger than the previously reported polyoxorin D, J075-4187, and chitotriose. The results are discussed in the context of potential synergism and molecular mode of action.

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Hymexazol (HML) is widely used in agriculture as a systemic fungicide and plant growth promoter. Humans are continuously exposed to HML via various routes. The liver and kidneys are essential organs for the detoxification, metabolism, and excretion of HML. However, data concerning the impact of HML on nontarget organisms are scarce. The present study aimed to determine the mechanism of dose-dependent hepatorenal toxicity of HML in rats. Twenty-one rats were divided into three equal groups that received the following treatments via oral intake daily for 14 days: group 1, normal saline; group 2, low dose of HML (1/80 LD50 ); group 3, high dose of HML (1/40 LD50 ). We weighed the rats at the beginning and the end of the experiment to record the weight gain in each group. The results showed that HML induced dose-dependent hepatorenal toxicity manifested by a significant increase in malondialdehyde levels, a decrease in total antioxidant capacity and reduced glutathione contents, and upregulation of the transcriptase levels of the nuclear factor kappa B (NF-κB), tumor necrosis factor alpha (TNF-α), and interleukin-1 beta (IL-1ß) genes. The HML-exposed groups displayed various histopathological changes in both organs, with significant elevation of all serum liver and kidney biomarkers. In conclusion, HML produced hepatorenal toxicity in rats through oxidative stress that mediates the NF-κB signaling pathway in response to pro-inflammatory cytokines such as TNF-α and IL-1ß. We advise limiting the use of HML in agricultural and veterinary practices and finding an alternative agent to avoid the human and animal health risks induced by HML exposure.

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Hymexazol (HYM) is irreplaceable for treating soil-borne diseases due to its high efficiency and low cost, as a broad-spectrum fungicide. However, when HYM is absorbed by plants, it is rapidly converted into two glycoside metabolites, and the antifungal activities of these glycosides are inferior to that of HYM. Therefore, in this study, to maintain strong antifungal activity in vitro and in vivo, HYM was glycosylated with amino sugars that have diverse biological activities to simulate plant glycosylation. The antifungal experiment proved that glycoside 15 has the highest antifungal activity, and N-acetyl glucosamine and HYM had obvious synergistic effects. According to the structure-activity relationship studies, glycoside 15 had greater numbers of active electron-rich regions and front-line orbital electrons due to the introduction of N-acetyl glucosamine. Moreover, glycoside 15 can significantly promote plant growth and induce an increase in plant defense enzyme activity. Additionally, compared to HYM, the results of electron microscopy and proteomics revealed that glycoside 15 has a unique antifungal mechanism. The promising antifungal activity and interactions with plants mean that glycoside 15 is a potential green fungicide candidate. Furthermore, this research conducted an interesting exploration of the agricultural applications of amino sugars.

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Pesticides are widely used in agriculture to kill pests, but their action is non-selective and results in several hazardous effects on humans and animals. Pesticide toxicity has been demonstrated to alter a variety of neurological functions and predisposes to various neurodegenerative diseases. Although, there is no data available for hexaflumuron (HFM) and hymexazol (HML) neurotoxicity. Hence, the present study aims to investigate the possible mechanisms of HFM and HML neurotoxicity. 21 male Wistar rats were divided into three groups and daily received the treatment via oral gavage for 14 days as follows: group (1) normal saline, group (2) HFM (1/100LD50), and group (3) HML (1/100 LD50). Our results revealed that both HFM and HML produced a significant increase in MDA levels and a decrease in GSH and CAT activity in some brain areas. There were severe histopathological alterations mainly neuronal necrosis and gliosis in different examined areas. Upregulation of mRNA levels of JNK and Bax with downregulation of Bcl-2 was also recorded in both pesticides exposed groups. In all studied toxicological parameters, HML produced neurotoxicity more than HFM. HFM targets the cerebral cortex and striatum, while HML targets the cerebral cortex, striatum, hippocampus, and cerebellum. We can conclude that both HFM and HML provoke neurobehavioral toxicity through oxidative stress that impairs the mitochondrial function and activates the JNK-dependent apoptosis pathway.

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The use of synthetic fungicide needs to be gradually reduced because of its adverse effect on human health and the environment. An integrated approach combining fungicides with biological control agents (BCAs) can be used to reduce the fungicide doses, thereby minimizing the risks associated with chemical fungicides. In this study, the combined application of a BCA Trichoderma and a fungicide hymexazol was used to manage the cowpea wilt disease caused by Fusarium oxysporum. The Trichoderma SC012 strain, which is resistant to hymexazol, was screened out and identified as T. asperellum. T. asperellum SC012 showed hyperparasitism to F. oxysporum and could penetrate and encircle the hyphae of pathogen on a medium amended or not with hymexazol. When combined with hymexazol, the population density in the rhizosphere soil of cowpea showed no significant difference compared with the treatment Trichoderma used alone. When the concentration of T. asperellum SC012 or hymexazol was halved, their combined application could control cowpea wilt disease more effectively than their individual use. The findings showed that the combination of Trichoderma and hymexazol could reduce the use of chemical fungicide, which is eco-friendly and may be an important part of integrated control of Fusarium wilt in cowpea.

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According to Article 12 of Regulation (EC) No 396/2005, EFSA has reviewed the maximum residue levels (MRLs) currently established at European level for the pesticide active substance hymexazol. To assess the occurrence of hymexazol residues in plants, processed commodities, rotational crops and livestock, EFSA considered the conclusions derived in the framework of Commission Regulation (EC) No 33/2008 as well as the European authorisations reported by Member States (including the supporting residues data). Based on the assessment of the available data, MRL proposals were derived and a consumer risk assessment was carried out. All information required by the regulatory framework was present and a risk to consumers was not identified.

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Hymexazol is an efficacious and widely used fungicide. However, its environmental toxicological assessment has not been well documented. It had no report of its toxicity to fish embryo. Fish embryo acute toxicity tests are highly predictive of aquatic embryotoxicity outcome. In this study, zebrafish (Danio rerio) embryos were exposed to hymexazol at varying concentrations for the study of the developmental toxicity, melanin biosynthesis, biochemical and transcriptional endpoints. The embryotoxicity tests indicated that the 96h LC50 value of hymexazol was 649mg/L with a 95% confidence interval range of 632-667mg/L. Hymexazol at concentrations of 417-738mg/L decreased the heart rate and increased the voluntary swing. Hymexazol inhibited normal development at concentrations above 554mg/L. the 96h EC50 was 411mg/L. Hymexazol in a concentration range of 417-738mg/L induced cardiac edema and yolk sac edema. Exposure of hymexazol at such concentrations to zebrafish embryos for 48h decreased the pigment area density compared with the no hymexazol control. Tyrosinase activity was inhibited by hymexazol relative to the untreated control. The P53 mRNA expression level in embryos upon exposure to 480mg/L or greater of hymexazol was significantly higher than that of the control. The results indicated that hymexazol has quite low acute toxicity and low embryotoxicity to zebrafish.

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Pesticide carrier systems are highly desirable in achieving the effective utilization of pesticides and reduction of their loss. In order to increase utilization and enhance pesticide adhesion to harmful targets, adhesive and stimulus-responsive nanocomposites were prepared using graphene oxide (GO) and polydopamine (PDA). The results demonstrated that graphene oxide with a layer of PDA had a high hymexazol-loading capacity. The release curve of hymexazol from the nanocomposite showed that the release was NIR-laser-dependent and pH-dependent. The adhesion-performance investigation demonstrated that Hy-GO@PDA exhibited greater hymexazol persistence than a hymexazol solution after a simulated-rainwash experiment, and it also left more hymexazol residue than a hymexazol solution with a surfactant under high concentrations. Finally, the bioactivity of the prepared hymexazol-loaded nanocomposite was measured against Fusarium oxysporum f. sp. cucumebrium Owen, and it showed an inhibition activity similar to that of the hymexazol solution. All of these revealed that GO with a PDA layer could serve as pesticide carrier to solve low-utilization and wash-off problems, especially for water-soluble pesticides.

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A rapid and sensitive method based on modified QuEChERS for hymexazol determination in 26 plant-derived foods using liquid chromatography tandem-mass spectrometry (LC-MS/MS) was developed. Variables affecting the separation (LC column, mobile phase additives) and clean-up effects of various dispersive phases, such as PSA, C18, GCB, MWCNTs, PEP-2, Al2O3, Florisil, and PVPP were evaluated. The method was validated using 26 matrices at spiked levels of 0.01 or 0.02, 0.05, 0.1, and 0.5mg/kg (0.05, 0.2, 0.5, and 1.0mg/kg for green tea). Mean recoveries were between 71.2% and 113.8%, and intra and inter-day precisions were below 14.8%. The limit of quantitation for 26 matrices ranged from 10 to 50µg/kg. Matrix-matched calibration was used. The method was subsequently applied for real sample analysis, and hymexazol was detected in a cucumber (below the LOQ) and was not detected in any other sample. The method is simple and effective, and meets the routine monitoring requirements for hymexazol residue in foods.

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The isoxazole structure is present in several pesticides. However, there is a lack of information about its degradation products after the release to the atmosphere. The main atmospheric reactions of hymexazol (5-methylisoxazol-3-ol), selected as representative model, were investigated at a large outdoor simulation chamber. The predominant products of atmospheric degradations were gaseous nitrogen derivates (nitric acid, nitrogen dioxide, nitrogen oxide, nitrous acid, and peroxyacetylnitrate), ozone, and small oxygenated compounds (formic acid, formaldehyde, and methylglyoxal). The aerosol yields were lower than 5%, and an OH rate-dependence was observed in the nucleation, particle growth, and size distribution. Also, the chemical composition of minor multi-oxygenated products was studied for OH-photo-oxidations. More than 20 products were detected in the gas or particulate phase. The most abundant were heterocyclic cleavage products with C4-chain and oxygenated moieties at positions 1 and 3, such as 3,4-dioxobutanoic acid, 3-oxobutanoic acid, and 3-oxobutanal. The suggested reaction pathway is the opening of heterocycle ring by the cleavage of N-O bond and C-N bond, releasing nitrogen oxides.

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