Concentrations Of Azoxystrobin Research Articles

Raman silent region – based method for detection of pesticides with cyano group

Based on the fact that not all chemical substances possess good Raman signals, this article focuses on the Raman silent region signals of pesticides with cyano group. Under the optimized conditions of methanol–water (1:1, v/v) as the solvent, irradiation at 302 nm light source for 20 min, and the use of 0.5 mol/L KI as the aggregating agent, Surface-enhanced Raman spectroscopy (SERS) method for azoxystrobin detection was developed by the Raman silent region signal of 2230 cm−1, and verified by detecting the spiked grapes with different concentrations of azoxystrobin. Other four pesticides with cyano group also could be identified at the peak of 2180 cm−1, 2205 cm−1, 2125 cm−1, and 2130 cm−1 for acetamiprid, phoxim, thiacloprid and cymoxanil, respectively. When azoxystrobin or acetamiprid was mixed respectively with chlorpyrifos without cyano group, their SERS signals in the Raman silent region of chlorpyrifos were not interfered, while mixed with cymoxanil in different ratios (1:4, 1:1 and 4:1), respectively, each two pesticides with cyano group could be distinguished by the changes in the Raman silent region. In further, four pesticides with or without cyano group were mixed together in 1:1:1:1 (acetamiprid, cymoxanil, azoxystrobin chlorpyrifos), and each pesticide still could be identified even at 0.5 mg/L. The results showed that the SERS method combined with UV irradiation may provide a new way to monitor the pesticides with C≡N performance in the Raman silent region without interference from the food matrix.

Co-detection of azoxystrobin and thiabendazole fungicides in mold and mildew resistant wallboards and in children

The study measured the levels of azoxystrobin (AZ) and thiabendazole (TBZ) in wallboards and metabolite levels of these fungicides in children. The paper covering of wallboard samples contained a higher concentration of AZ and TBZ than the gypsum core, and similar amounts (w/w) of these two fungicides were present in the samples. These data suggest that commercial products containing a 1:1 (w/w) amount of AZ and TBZ, such as Sporgard® WB or Azo Tech™, were applied to the wallboard paper. This is the first detection of TBZ in mold-and-mildew resistant wallboards. The TBZ metabolite, 5OH-TBZ, was detected in 48% of urine samples collected from children aged 40–84 months, and was co-detected with AZ-acid, a common AZ metabolite, in 37.5% of the urine samples. The detection frequency of 5OH-TBZ was positively associated with the detection frequency of AZ-acid. These findings suggest that certain types of wallboards used in homes and commercial buildings may be a potential source of co-exposure to AZ and TBZ in humans.

Fungicides from rice cultivation (tebuconazole and azoxystrobin) alters biochemical and histological markers of hammertoad tadpoles (Boanafaber).

Tebuconazole (TBZ) and azoxystrobin (AZX) are fungicides frequently used in rice cultivation. Despite protecting crops against fungal diseases, these compounds can contaminate the natural environments close to the crops, exerting negative effects on non-target organisms, the present study aimed to characterize the contamination by fungicides of a river that flows in an area dominated by rice cultivation in the north of the state of Santa Catarina, SC, Brazil. Concentrations of TBZ and AZX found in the field were used to evaluate their negative effects on development, biochemical biomarkers and histopatology of the liver of a native tadpole species, the hammerfrog (Boana faber). Tadpoles were exposed for 16 days to the lowest (1.20 μg/L) and highest (2.60 μg/L) concentration of TBZ, lowest (0.70 μg/L) and highest (1.60 μg/L) concentration of AZX, and the mix of both fungicides at lowest and highest concentration of each found in field analyses. Exposure to the lower TBZ concentration and both concentrations of the Mix accelerated the development of tadpoles. AZX caused an increase in the activities of glutathione S-transferase (GST), carboxylesterase (CbE) and glucose-6-phosphate dehydrogenase (G6PDH) in the liver, an increase in the levels of protein carbonyls (PC) in the liver and an increase in the activity of acetylcholinesterase (AChE) in muscle of tadpoles. TBZ, on the other hand, generated an increase in GST, G6PDH, PC and histopathological severity scores in liver and in muscle AChE activity. The effects were more intense in the groups exposed to the Mix of contaminants. No treatment altered brain AChE. The data showed that the fungicides from in rice cultivation found in natural aquatic environments around the crops pose risks to the health of the animals, compromising their metabolism and development.

Enhanced Adsorption of Azoxystrobin from Water by As-Prepared Silica Nanoparticles

Nanoparticles are of great interest for water treatment as they remove a significant portion of water contaminants. In analogy to these emerging practices, the present work investigated the feasibility of using silica nanoparticles (SiO2-NPs) to remove azoxystrobin from an aqueous solution. We investigated the effects of experimental parameters, such as solution temperature, adsorbent dosage, contact time, and initial azoxystrobin concentration, on the removal efficiency of azoxystrobin. Structural and chemical analysis of the synthesized nanoparticles was performing using X-ray diffraction patterns (XRD), scanning electron microscopy (SEM), dynamic light scattering (DLS), and surface studies. The percentage of azoxystrobin removal efficiency was 92.8 at an initial azoxystrobin concentration of 10 mg/L. The result showed that by increasing the adsorbent dosage from 0.005 to 0.1 mg, the percentage removal efficiency of azoxystrobin from aqueous solution increased significantly from 59.72% to 95.21%. At the same time, the adsorption amount of azoxystrobin in equilibrium decreased with increasing temperature. It was found that the optimum temperature for removing azoxystrobin was 20 °C. Although the study was conducted under well-controlled laboratory conditions, the silica nanoparticle system showed excellent performance in removing a significant amount of azoxystrobin, making it a potential alternative/cooperator in water treatment for removing pesticides from aqueous solutions.

Temporal dynamics of total and bioavailable fungicide concentrations in soil and their effect upon nine soil microbial markers

Pesticides constitute an integral part of today's agriculture. Their widespread use leads to ubiquitous contamination of the environment, including soils. Soils are a precious resource providing vital functions to society — thus, it is of utmost importance to thoroughly assess the risk posed by widespread pesticide contamination. The exposure of non-target organisms to pesticides in soils is challenging to quantify since only a fraction of the total pesticide concentration is bioavailable. Here we measured and compared the bioavailable and total concentrations of three fungicides – boscalid, azoxystrobin, and epoxiconazole – and evaluated which concentration best predicts effects on nine microbial markers. The experiments were performed in three different soils at five time points over two months employing nearly 900 microcosms with a model plant. The total and bioavailable concentrations of azoxystrobin and boscalid decreased steadily during the trial to levels of 25 % and 8 % of the original concentration, respectively, while the concentration of epoxiconazole in soil nearly remained unchanged. The bioavailable fraction generally showed a slightly faster and more pronounced decline. The microbial markers varied in their sensitivity to the three fungicides. Specific microbial markers, such as arbuscular mycorrhizal fungi, and bacterial and archaeal ammonia oxidizers, were most sensitive to each of the fungicide treatments, making them suitable indicators for pesticide effects. Even though the responses were predominantly negative, they were also transient, and the impact was no longer evident after two months. Finally, the bioavailable fraction did not better predict the relationships between exposure and effect than the total concentration. This study demonstrates that key microbial groups are temporarily susceptible to a single fungicide application, pointing to the risk that repeated use of pesticides may disrupt vital soil functions such as nutrient cycling in agroecosystems.

The kisspeptin-GnIH signaling pathway in the role of zebrafish courtship and aggressive behavior induced by azoxystrobin

Azoxystrobin, a strobilurin widely used to control rice diseases, has raised concerns about possible adverse effects on aquatic ecosystems. At present, very little is known about the effects of azoxystrobin on courtship and aggressive behavior and the potential underlying mechanisms. In the present study, after exposing adult male and female zebrafish to worst-case scenario concentrations of azoxystrobin (0, 2 μg/L, 20 μg/L, and 200 μg/L) for 42 d, we observed a decrease in courtship behavior and an increase in aggressive behavior in both male and female zebrafish. In addition, to elucidate the molecular mechanism of the behavioral effects of azoxystrobin, we quantified the changes in the concentrations of kisspeptin, 5-HT, GnIH, and their corresponding receptor mRNA expression in the brain. The results showed that 200 μg/L azoxystrobin decreased the concentrations of kisspeptin and increased the concentration of GnIH in both male and female zebrafish brain. In addition, azoxystrobin also significantly reduced 5-HT concentration in female zebrafish brain. Further investigation revealed that altered courtship and aggressive behavior were associated with the expression levels of genes (kiss1, kiss2, gnrh3, gnrhr3, 5ht1a, and 5ht2a) involved in kisspeptin-GnIH signaling pathway. In conclusion, our study suggested that azoxystrobin may impair courtship and aggressive behavior in zebrafish by interfering with the kisspeptin-GnIH signaling pathway, which may have more profound effects on natural zebrafish populations.

Fumonisin reduction using fungicides in forage corn cultivation

AbstractThis study investigated the possibility of a reduced‐fumonisin corn cultivation method using two fungicides, azoxystrobin and propiconazole. A field‐based cultivation experiment was conducted, wherein Kimimaru and LG3490 corn were cultivated for 2 years with a fungicide applied. In the first year, the use of fungicides reduced the concentration of fumonisin in corn, but in the following years, no fumonisin‐reducing effect was observed. Differences in precipitation may be the cause, but details were unknown. Although a minor effect was observed, the results suggested that the method was not wholly effective. Next, in an in vitro incubation experiment, the relationship between fumonisin‐producing fungi (Fusarium fujikuroi) and fumonisin production was examined in the presence of two fungicides. Both fungicides reduced F. fujikuroi cell mass in a concentration‐dependent manner. Fumonisin production did not decrease noticeably at low fungicide concentrations but at high concentrations. This indicates that a fungicide concentration above a certain threshold is required to suppress fumonisin production. The fumonisin produced per fungal cell mass remained almost constant between 0.1 and 10 mg/L propiconazole, although it decreased to zero at higher propiconazole concentrations. Thus, the propiconazole‐induced decrease in fumonisin production was likely caused by a reduction in fungal cell mass. In contrast, fungal cell mass decreased as azoxystrobin concentration increased, and the azoxystrobin produced per cell mass reduced. Thus, fumonisin production was synergistically suppressed by decreased cell mass and production. The results of both experiments did not exhibit the desired level of reduction effect likely because a sufficiently high concentration of fungicide could not be maintained for outdoor cultivation. Various other factors, such as weather conditions, may have affected the disinfectant concentration, leading to the reduced fungicide concentration.

Comparing imidacloprid, clothianidin, and azoxystrobin runoff from lettuce fields using a soil drench or treated seeds in the Salinas Valley, California

Neonicotinoid insecticide use has increased over the last decade, including as agricultural seed treatments (application of chemical in a coating to the seed prior to planting). In California, multiple crops, including lettuce, can be grown using neonicotinoid treated seeds or receive a direct neonicotinoid soil application (drenching) at planting. Using research plots, this study compared pesticide runoff in four treatments: (1) imidacloprid seed treatment; (2) clothianidin seed treatment; (3) imidacloprid drench and an azoxystrobin seed treatment; and (4) a control with no pesticidal treatment. Neonicotinoid and azoxystrobin concentrations were measured in surface water runoff during six irrigations events in the 2020 growing seasons. Results showed runoff concentrations up to 1308 (±1200) ng L−1 for imidacloprid drench treatment, 431 (±100) ng L−1 for clothianidin seed treatment, 135 (±60) ng L−1 for imidacloprid seed treatment, and 13 (±10) ng L−1 for azoxystrobin seed treatment (treatments averaged). The percent of applied mass in runoff over the entire sampling period varied by compound; the imidacloprid seed treatment and drench were similar (0.015 and 0.019%, respectively) to the clothianidin seed treatment (0.036%) while the azoxystrobin seed treatment was much higher (15%). Although the proportion of imidacloprid in runoff was similar for imidacloprid treatments, the mass applied during soil drench was > 4x the amount applied from the imidacloprid seed treatment. Surface soils were collected before planting and at the end of the trial. The neonicotinoids were detected in soil throughout the study and average maximum concentrations were 9–13 ng g−1; azoxystrobin was detected in only two soils at concentrations up to 0.57 ng g−1. These results elucidate the comparative mass runoff resulting from planting treated seed and soil drench applications and highlight the value of additional work to characterize off-site transport from the many commodities that may be utilizing treated seeds.

Obtaining effective biodestructors of fungicidal drugs for environmental agrobiocenoses’ maintenance sustainability

Agrobiocenoses are highly productive communities. However, their resistance is low due to the artificially limited species diversity, susceptibility to diseases and pests, and the impossibility of self-recovery. The constant use of pesticides for plant protection further reduces the resistance of agrocenoses due to the toxicity of the components for the soil microbiota and pollinating insects. The accumulation and migration of toxic components of pesticides leads to an increase in the environmental load on surface water bodies and aquatic organisms. The impossibility of abandoning the use of fungicidal preparations and the need to develop ways to increase the ecological stability of agrobiocenoses determined the relevance of the studies described in the article. In the course of the experiment, pure cultures of 9 microbial strains-destructors of strobilurins and triazoles - active substances of widely used fungicides -were isolated from environmental objects. A comparative assessment of the ability of the isolated strains to consume high concentrations of azoxystrobin and cyproconazole was carried out. It was found that the Bacillus thuringiensis strain, which is capable of growing on media containing up to 100 APC for soil in the absence of other carbon sources, has the greatest activity. B. thuringiensis is promising as the basis of a biological product for the recultivation of soils contaminated with fungicides of the strobilurin and triazole classes. To obtain the biomass of the biodestructor, the optimal cultivation parameters were determined: temperature 37 ºC and the composition of the nutrient medium based on glucose and peptone with microelements: Mg, Fe, Zn, Mn, B.

Assessment of Quinone Outside Inhibitor Sensitivity and Frogeye Leaf Spot Race of Cercospora sojina in Georgia Soybean.

Frogeye leaf spot (FLS), caused by the fungal pathogen Cercospora sojina K. Hara, is a foliar disease of soybean (Glycine max L. [Merr.]) responsible for yield reductions throughout the major soybean-producing regions of the world. In the United States, management of FLS relies heavily on the use of resistant cultivars and in-season fungicide applications, specifically within the class of quinone outside inhibitors (QoIs), which has resulted in the development of fungicide resistance in many states. In 2018 and 2019, 80 isolates of C. sojina were collected from six counties in Georgia and screened for QoI fungicide resistance using molecular and invitro assays, with resistant isolates being confirmed from three counties. Additionally, 50 isolates, including a "baseline isolate" with no prior fungicide exposure, were used to determine the percent reduction of mycelial growth to two fungicides, azoxystrobin and pyraclostrobin, at six concentrations: 0.0001, 0.001, 0.01, 0.1, 1, and 10 μg ml-1. Mycelial growth observed for resistant isolates varied significantly from both sensitive isolates and baseline isolate for azoxystrobin concentrations of 10, 1, 0.1, and 0.01 μg ml-1 and for pyraclostrobin concentrations of 10, 1, 0.1, 0.01, and 0.001 μg ml-1. Moreover, 40 isolates were used to evaluate pathogen race on six soybean differential cultivars by assessing susceptible or resistant reactions. Isolate reactions suggested 12 races of C. sojina present in Georgia, 4 of which have not been previously described. Species richness indicators (rarefaction and abundance-based coverage estimators) indicated that within-county C. sojina race numbers were undersampled in this study, suggesting the potential for the presence of either additional undescribed races or known but unaccounted for races in Georgia. However, no isolates were pathogenic on 'Davis', a differential cultivar carrying the Rcs3 resistance allele, suggesting that the gene is still an effective source of resistance in Georgia.

Pollen nutrition fosters honeybee tolerance to pesticides.

A reduction in floral resource abundance and diversity is generally observed in agro-ecosystems, along with widespread exposure to pesticides. Therefore, a better understanding on how the availability and quality of pollen diets can modulate honeybee sensitivity to pesticides is required. For that purpose, we evaluated the toxicity of acute exposure and chronic exposures to field realistic and higher concentrations of azoxystrobin (fungicide) and sulfoxaflor (insecticide) in honeybees provided with pollen diets of differing qualities (named S and BQ pollens). We found that pollen intake reduced the toxicity of the acute doses of pesticides. Contrary to azoxystrobin, chronic exposures to sulfoxaflor increased by 1.5- to 12-fold bee mortality, which was reduced by pollen intake. Most importantly, the risk of death upon exposure to a high concentration of sulfoxaflor was significantly lower for the S pollen diet when compared with the BQ pollen diet. This reduced pesticide toxicity was associated with a higher gene expression of vitellogenin, a glycoprotein that promotes bee longevity, a faster sulfoxaflor metabolization and a lower concentration of the phytochemical p-coumaric acid, known to upregulate detoxification enzymes. Thus, our study revealed that pollen quality can influence the ability of bees to metabolize pesticides and withstand their detrimental effects, providing another strong argument for the restoration of suitable foraging habitat.

Role of Yeasts in the Cranberry Fruit Rot Disease Complex.

Cranberry fruit rot (CFR) is an economically important disease caused by at least 10 species of filamentous fungi. Despite the application of fungicides, incidence of CFR is sometimes high, raising the possibility of a role for microbes other than fungi in the CFR complex. Isolation of microbes from rotten berries on culture media that favor either bacteria or yeasts resulted in mucoid colonies from <15% of dry-harvested rotten berries but up to 60% of wet-harvested berries. The mucoid colonies were identified as yeasts, primarily in the family Saccharomycetaceae. Inoculation of sound berries with three yeasts, Hanseniaspora uvarum, Pichia fermentans, and Pichia terricola, resulted in significantly higher incidence and severity of rot symptoms compared with mock-inoculated controls; these yeasts were recovered from inoculated berries, providing evidence of their pathogenicity. The minimum concentrations of azoxystrobin, chlorothalonil, and prothioconazole that resulted in 80% inhibition of growth compared with untreated controls (MIC80) were determined for a subset of yeasts. In general, MIC80s were higher for azoxystrobin and prothioconazole (usually >64 µg/ml) than for chlorothalonil (usually ≤1 µg/ml). To complement culture-dependent studies, DNA was isolated from wet- and dry-harvested rotten berries, and fungi were identified to the level of family by high-throughput sequencing of the fungal internal transcribed spacer region. There were no fungal families consistently detected among samples by one method (culturing or high-throughput sequencing) and missed by the other that have not previously been reported in cranberry; however, some fungal families were found to be more abundant by one method versus the other. Harvest method (wet or dry) had a significant effect on the composition of fungal communities of rotten berries (P < 0.001), and operational taxonomic units representing the Saccharomycetaceae were more abundant in wet- than dry-harvested berries. Taken together, the results suggest that some yeasts are pathogenic to cranberry and may be especially relevant in wet-harvested berries.

In Vitro Efficiency of Some Fungicides Against Neoscytalı̇dı̇um dı̇mı̇dı̇atum (Penz.) Crous and Slippers Causing Sudden Shoot Dry on Apricot Trees

Turkey is known as a top producer and exporter of apricots, both fresh and dried. More than half of Turkey's apricot production is provided by Malatya province. There are many pests and diseases affecting apricots in addition to climatic factors such as frost and hail. Partial shoot drying and sudden drying in apricot orchards have increased in recent years. In this study, it was aimed to determine the chemical control possibilities of Neoscytalidium dimidiatum (Penz.) Crous &amp;Slippers, which is one of the fungal agents that cause partial branch drying and sudden drying in apricot orchards in Malatya province by in vitro studies. For this purpose, Kale 4-C isolate of N. dimidiatum collected from Malatya in a previous study was used. Mycelial growth of N. dimidiatum Kale 4-C isolate in PDA were observed in 0 (control), 0.01, 0.03, 0.1, 1, 3, 10, 30 ve 100 μg/mL concentrations of Azoxystrobin 250g/L, Trifloxystrobin %50, Tebuconazole %25, Floupyram 200 g/L+Tebuconazole 200 g/L, Cyprodinil+Fludioxonil %37.5+25, %70 Thiophanate-Methyl and 400 g/L Phosphorous acide fungicides applications. As a result of the study, Floupyram 200g/L+Tebuconazole 200g/L ve Cyprodinil+Fludioxonil %37.5+25 fungicides effectively inhibited the mycelial growth of the fungus.

Embryonic zebrafish response to a commercial formulation of azoxystrobin at environmental concentrations

Azoxystrobin is a broad-spectrum strobilurin fungicide for use on a wide range of crops available to end-users as formulated products. Due to its extensive application, it has been detected in aquatic ecosystems, raising concerns about its environmental impact, which is still poorly explored. The objective of this work was to study the effects of a commercial formulation of azoxystrobin in the zebrafish embryo model. Sublethal and lethal effects were monitored during the exposure period from 2 h post fertilisation (hpf) to 96 hpf after exposure to azoxystrobin concentrations (1, 10 and 100 μg L−1). The responses of antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR)) as well as detoxifying enzymes (glutathione-s-transferase (GST) and carboxylesterase (CarE)) were evaluated at 96 hpf. Similarly, glutathione levels (reduced (GSH) and oxidised (GSSG) glutathione), neurotransmission (acetylcholinesterase (AChE)) and anaerobic respiration (lactate dehydrogenase (LDH)) -related enzymes were assayed. At 120 hpf, larvae from each group were used for behaviour analysis. Results from this study showed concentration-dependent teratogenic effects, particularly by increasing the number of malformations (yolk and eye), with a higher prevalence at the highest concentration. However, it was found that the lowest concentration induced a high generation of reactive oxygen species (ROS) and increased activity of SOD, GST, and CarE. In addition, GR and GSSG levels were decreased by the lowest concentration, suggesting an adaptive response to oxidative stress, which is also supported by the increased AChE activity and absence of behavioural changes. These findings advance the knowledge of the azoxystrobin developmental and environmental impacts, which may impose ecotoxicological risks to non-target species.

Growth-inhibiting effect of azoxystrobin and its ability to inhibit sugar consumption in winter wheat sprouts and roots

This study aimed to assess the prospects for the use of azoxystrobin, a fungicide of the strobilurin class, for increasing the resistance of winter wheat to low temperatures. The effect of azoxystrobin on growth processes, cell viability and the content of water-soluble carbohydrates in winter wheat (Triticum aestivum L.), the Ikutskaya variety, was studied. In comparison with other synthetic strobilurins, azoxystrobin is more frequently used in multicomponent fungicidal preparations. Azoxystrobin is a broad-spectrum fungicide that inhibits complex III of the mitochondrial electron transport chain. Experiments were carried out in laboratory conditions using 3-day-old etiolated winter wheat sprouts. The sprouts were grown in a dark place at a temperature of +24 °C on azoxystrobin solutions dissolved in a 0.36% aqueous solution of dimethyl sulfoxide, distilled water and a 0.36% dimethyl sulfoxide solution. The effect of various azoxystrobin concentrations (2.5, 5, 10 and 20 μM) on the growth of sprouts and roots was assessed, along with the viability of sprout and root cells. Azoxystrobin had a concentration-dependent growth-inhibiting effect on sprouts and roots. At concentrations of 2.5 μM and 20 μM, the inhibition degree for sprouts varied from 2.8% to 41.7%, respectively. For roots, these values comprised 34.6 and 63.1%, respectively. The growth-inhibiting effect was not accompanied by a decrease in the cell viability of sprouts and roots, which was assessed using in vivo staining with fluorescein diacetate (FDA). The effect of azoxystrobin at a concentration of 10 μM on the sugar content in germinated sprouts was also evaluated. At this concentration of azoxystrobin, the sugar content was higher by 3.6% in sprouts germinated on a dimethyl sulfoxide solution. Since growth inhibition and sugar accumulation are important factors in plant adaptation to low temperatures, further research into effects of azoxystrobin on the physiological and biochemical parameters of plants associated with the development of low-temperature resistance seems justified.

Distribution of Alternaria alternata isolates with resistance to quinone outside inhibitor (QoI) fungicides in Brazilian orchards of tangerines and their hybrids

Alternaria brown spot (ABS), caused by Alternaria alternata, has been controlled with sprays of quinone outside inhibitors (QoI), demethylation inhibitors (DMI) and copper-based fungicides. QoI fungicides have been intensively used for citrus disease control in São Paulo (SP) since 2003, when ABS was first found in the state. In 2017, citrus growers from several regions in SP stated experiencing failures in ABS control with the use of QoI fungicides. This study was then proposed to assess the sensitivity of A. alternata isolates to QoI fungicides by conidial germination and resazurin microtiter assay, and also to determine the geographic distribution of sensitive and resistant isolates in areas cultivated with tangerines and their hybrids in SP. One hundred and twenty-eight A. alternata isolates were sampled in nine municipalities in different SP regions in 2017 and 2018. Isolates collected in 2003/2004, immediately after the first report of ABS in SP, were used as baseline. Effective concentrations of azoxystrobin and pyraclostrobin to reduce conidial germination by 50% (EC50) were estimated and A. alternata isolates were classified as resistant when the conidial germination rate was ≥50% at a discriminatory rate of 1 μg mL−1. Isolates resistant to QoI fungicides were widely found throughout SP regions, and no pattern in resistance distribution was observed. In five out of the nine municipalities, 100% of isolates were resistant to both fungicides, while in other four municipalities the percentage of resistant isolates to azoxystrobin (46%–100%) was higher than that of pyraclostrobin (15%–93%). The G143A mutation positively correlated with the resistance phenotype to azoxystrobin for all A. alternata isolates and to pyraclostrobin for most of them. The resazurin microtiter assay proved useful for rapid qualitative classification of sensitive and resistant A. alternata isolates. Our results suggest the need for anti-resistance strategies in the chemical management of the disease in the state.

In vitro effect of some commercial fungicides on mycelial growth of Fusarium species causing maize ear rot disease in China

Fusarium ear rot is an important disease of maize and requires several fungicide treatments to achieve satisfactory control in China. The extensive use of common fungicides to control this disease has caused fungicides resistance of pathogens. In this study, we tested the effect of different commercial fungicides on mycelial growth of Fusarium graminearum and Fusarium oxysporum isolates collected from different fields in the Jilin Province of China in 2014. The effect of concentration on mycelial growth varied significantly (p < 0.05) between tested commercial fungicides. Our results showed that among the 10 tested commercial fungicides, prochloraz and polyoxin-D highly reduced the mycelial growth of Fusarium graminearum by 3.4 cm and 4.1 cm, respectively as compared to other fungicides at a concentration of 0.1 mg/L. Moreover, a 0.1 mg/L concentration of polyoxin-D, tebuconazole, fosetyl-Al, fludioxonil, azoxystrobin, and carbendazim were also highly effective to decrease the mycelial growth of Fusarium oxysporum with 3.1 cm, 3.1 cm, 3.4 cm, 3.8 cm, and 4.4 cm as compared to other fungicides at the same concentration. These results will provide useful information to select suitable fungicides for management and control of maize ear rot disease caused by Fusarium graminearum and Fusarium oxysporum and further increase our understanding of the effects of different fungicides concentrations on Fusarium graminearum and Fusarium oxysporum.

Effect of household rice cooking on pesticide residues

This investigation shows the pesticide distribution and reduction using three common household cooking methods. Extraction was performed using QuEChERS and solid phase microextraction methodologies for rice and water, respectively. Gas chromatography-mass spectrometry was used. Both methods showed good linearity (r2 > 0.9996 and 0.9945), adequate recoveries (between 98.9 and 107.8% and 90.5–104.2%) and relative standard deviations lower than 4.5% and 7.0%, for rice and water, respectively. The initial concentration of deltamethrin, penconazole, kresoxim-methyl, cyproconazole, epoxiconazole and azoxystrobin, were 84.9, 242.2, 298.5, 230.7, 253.4 and 293.5 µg/kg, respectively. Washing and soaking water reduce pesticides only 0.40 to 4.28%. The pesticide reduction during cooking were 20.73 to 57.72%, 32.74 to 70.39%, and 68.87 to 87.50% for traditional, excess water, and pre-soaking rice methods, respectively. Pre-soaking rice with extra water before cooking proved to be the method that generates the greatest reduction.

The distributions of three fungicides in vegetables and their potential health risks in Zhejiang, China: A 3-year study (2015–2017)

Fungicides have been extensively used around the world in agriculture due to their effectiveness of sterilization. Recent evidences have shown that fungicides would exert a negative effect on gut microbiota and result in gut microbiota dysbiosis and metabolism disorder on non-target organisms and even humans. However, research on residues and potential health risks of fungicides in daily consumed vegetables has received less attention compared to insecticides. In this study, we studied three widely applied fungicides, procymidone, dimethomorph, and azoxystrobin, in China. We collected 551 samples of 10 different vegetables in 11 cities from Zhejiang province during 2015–2017. Three fungicides were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The average apparent recoveries of three fungicides ranged from 84.2% to 110% with the relative standard deviations lower than 10%. The LOD values of procymidone, dimethomorph, and azoxystrobin was 2, 0.09, and 1 μg/kg, respectively. The levels of procymidone, dimethomorph, and azoxystrobin in those vegetables ranged from ND-875, ND-238, and ND-76 μg/kg, respectively. The highest mean concentrations of procymidone, dimethomorph, and azoxystrobin were found in eggplant (68 μg/kg), spinach (16.4 μg/kg), and kidney bean (4 μg/kg), respectively. Tomato (62.6% of samples), eggplant (44.3% of samples), and cucumber (41.6% of samples) were most frequently detected with fungicides. Solanaceous fruit vegetables have the highest detection rate than other vegetables, and fungicides were most frequently detected in winter. The mean concentrations of three fungicides in different vegetables were all below the maximum residue limits for the national food safety standards of China, and the health risks resulting from consuming those vegetables in adults and children were all within the safe ranges. The data provided here clarify the distributions of fungicides in commonly consumed vegetables and their potential health risks.

Metabolomic modulations in a freshwater microbial community exposed to the fungicide azoxystrobin

An effective broad-spectrum fungicide, azoxystrobin (AZ), has been widely detected in aquatic ecosystems, potentially affecting the growth of aquatic microorganisms. In the present study, the eukaryotic alga Monoraphidium sp. and the cyanobacterium Pseudanabaena sp. were exposed to AZ for 7 days. Our results showed that 0.2–0.5 mg/L concentrations of AZ slightly inhibited the growth of Monoraphidium sp. but stimulated Pseudanabaena sp. growth. Meanwhile, AZ treatment effectively increased the secretion of total organic carbon (TOC) in the culture media of the two species, and this phenomenon was also found in a freshwater microcosm experiment (containing the natural microbial community). We attempted to assess the effect of AZ on the function of aquatic microbial communities through metabolomic analysis and further explore the potential risks of this compound. The metabonomic profiles of the microcosm indicated that the most varied metabolites after AZ treatment were related to the citrate cycle (TCA), fatty acid biosynthesis and purine metabolism. We thereby inferred that the microbial community increased extracellular secretions by adjusting metabolic pathways, which might be a stress response to reduce AZ toxicity. Our results provide an important theoretical basis for further study of fungicide stress responses in aquatic microcosm microbial communities, as well as a good start for further explorations of AZ detoxification mechanisms, which will be valuable for the evaluation of AZ environmental risk.