pyrachlostrobin and carbendazim

Topics: Animals; Bees; China; Crops, Agricultural; Food Contamination; Humans; Pesticide Residues; Pesticides; Risk Assessment; Vegetables

Winter is the key period for the control of apple diseases, and fungicides are needed to protect the trunk or main branches. Fungicide residue in apple tree bark is an important basis for the action of the pesticide, but there are no reports on analytical methods or dissipation patterns. In this work, thiophanate-methyl, carbendazim, tebuconazole and pyraclostrobin were selected as typical fungicides and a new QuEChERS-HPLC-VWD(QuEChERS extraction followed by high-performance liquid chromatography detection with a variable wavelength detector) analytical method was developed to estimate their residue kinetics in apple tree bark during the winter months. In the pretreatment step, the sorbent for the clean-up of extracts was optimized as 60 mg/ml primary secondary amine and a gradient-elution model followed by a variable wavelength detection was developed for instrumental analysis. Then this method was validated and applied to the analysis of apple tree bark samples with the linearity range of 0.010-50.00 mg/L, quantification limit range of 0.028-0.080 mg/kg and recovery range of 86.1-101.4%. The dissipation kinetics of thiophanate-methyl and pyraclostrobin could be described by the first-order and two-phase kinetics models, respectively. For carbendazim and tebuconazole, two new models were developed to describe their residue kinetics.

Topics: Benzimidazoles; Carbamates; Chromatography, High Pressure Liquid; Fungicides, Industrial; Linear Models; Malus; Pesticide Residues; Plant Bark; Reproducibility of Results; Sensitivity and Specificity; Spectrophotometry, Ultraviolet; Strobilurins; Thiophanate; Triazoles

In this study, the quality of surface water in the headwaters of São Lourenço River in Mato Grosso, Brazil, was evaluated in relation to contamination by pesticides. For this purpose, samples were collected between December 2015 and June 2016 by grab sampling and by passive sampling using an integrative polar organic compound sampler installed in the field during four 14-day cycles between March and June 2016. The analyses were performed by gas chromatography (CG/MS) and by liquid chromatography (UPLC-MS/MS). The results showed the detection of two pesticides (atrazine and pyraclostrobin) of the five analyzed by passive sampling and eight active principles among the 20 analyzed (malathion, diuron, carbofuran, carbendazim, trifluralin, imidacloprid, metolachlor, and acetamiprid) by grab sampling. The detection of 10 pesticides, even almost a decade after the beginning of a recovery process of the ciliary forest, confirms the headwaters' vulnerability to these contaminants and passive sampling proved to be an important tool in capturing small concentrations of pesticides constituting an interesting complement to grab sampling.

Topics: Acetamides; Atrazine; Benzimidazoles; Brazil; Carbamates; Carbofuran; Diuron; Environmental Monitoring; Gas Chromatography-Mass Spectrometry; Malathion; Neonicotinoids; Nitro Compounds; Pesticides; Rivers; Strobilurins; Tandem Mass Spectrometry; Trifluralin; Water Pollutants, Chemical

Crop protection agents are widely used in modern agriculture and exert direct effects on non-target microorganisms such as yeasts. Yeasts abundantly colonize wheat grain and affect its chemical composition. They can also limit pathogen growth. This study evaluated the sensitivity of yeast communities colonizing winter wheat kernels to benzimidazole, strobilurin, triazole and morpholine fungicides, trinexapac-ethyl, a commercial mixture of o-nitrophenol+p-nitrophenol+5-nitroguaiacol, and chitosan applied during the growing season of winter wheat and in vitro in a diffusion test. A molecular identification analysis of yeasts isolated from winter wheat kernels was performed, and nucleotide polymorphisms in the CYTb gene (G143A) conferring resistance to strobilurin fungicides in yeast cells were identified. The size of yeast communities increased during grain storage, and the total counts of endophytic yeasts were significantly (85%) reduced following intensive fungicide treatment (fenpropimorph, a commercial mixture of pyraclostrobin, epoxiconazole and thiophanate-methyl). This study demonstrated that agrochemical residues in wheat grain can drive selection of yeast communities for reduced sensitivity to xenobiotics. A mutation in the CYTb gene (G143A) was observed in all analyzed isolates of the following azoxystrobin-resistant species: Aureobasidium pullulans, Debaryomyces hansenii, Candida albicans and C. sake. Agrochemicals tested in vitro were divided into four classes of toxicity to yeasts: (1) tebuconazole and a commercial mixture of flusilazole and carbendazim - most toxic to yeasts; (2) fenpropimorph and a commercial mixture of pyraclostrobin and epoxyconazole; (3) propiconazole, chitosan, thiophanate-methyl and a commercial mixture of o-nitrophenol, p-nitrophenol and 5-nitroguaiacol; (4) trinexapac-ethyl and azoxystrobin - least toxic to yeasts. It was found that agrochemicals can have an adverse effect on yeast abundance and the composition of yeast communities, mostly due to differences in fungicide resistance between yeast species, including the clinically significant C. albicans.

Topics: Agaricales; Agrochemicals; Ascomycota; Benzimidazoles; Candida albicans; Carbamates; Drug Resistance, Fungal; Epoxy Compounds; Fungicides, Industrial; Microbial Sensitivity Tests; Pesticide Residues; Plant Diseases; Pyrimidines; Seasons; Silanes; Strobilurins; Triazoles; Triticum; Xenobiotics; Yeasts

Topics: Benzimidazoles; Carbamates; Chromatography, High Pressure Liquid; Chromatography, Liquid; Citrus; Pesticide Residues; Pyrazoles; Soil; Strobilurins; Tandem Mass Spectrometry; Thiophanate