Tetraconazole alters the methionine and ergosterol biosynthesis pathways in Saccharomyces yeasts promoting changes on volatile derived compounds.

The influence of antifungal tetraconazole residues (either as an active substance or as a commercial formulation product) on the fermentative activity of Saccharomyces cerevisiae yeast was evaluated in pasteurized Garnacha red must by using laboratory-scale fermentation assays. The presence of this fungicide promoted a slight decrease in glucose consumption. Volatile fermentative-derived compounds were evaluated in deep. Statistically significant changes were found in methionol (with a mean decrease of around 24%), fatty acids (with increments ranged from 23% to 66%), and ethyl esters (with increases ranged from 23% to 145%) contents when grape musts were enriched with the commercial formulation at both contamination levels assayed. Based on protein mass fingerprinting analysis, it was possible to relate these variations on volatiles content with changes in the activity of several enzymes (Met3p, Met14p, Adh2p, Hmg1p, Erg5p, Erg6p, Erg11p, and Erg20p) involved in the secondary metabolism of yeasts.

Mepanipyrim residues on pasteurized red must influence the volatile derived compounds from Saccharomyces cerevisiae metabolism.

The impact of mepanipyrim (Mep) and its corresponding commercial formulation (Mep Form) on Saccharomyces cerevisiae metabolites was assessed, separately, by using laboratory-scale wine fermentation assays on pasteurized red must. The presence of Mep did not alter the fermentation course. With regard to volatiles formed at the intracellular level by fermenting yeast cells, Mep residues affected mainly the acetate and ethyl ester biochemical pathways. In particular, the target acetates showed a notorious increment, >90%, in presence of commercial Mep Form at the higher dose assayed. The addition of Mep and Mep Form, at both tested levels, highly increased ethyl caprylate (between 42 and 63%) and ethyl caprate (between 36 and 60%) contents as the same as their respective fatty acid precursors. No important effects were observed on colour and non-volatile pyranoanthocyanins, probably due to the low anthocyanin content characteristic of pasteurized musts.

Effects of hydrochemistry variables on the half-life of mancozeb and on the hazard index associated to the sum of mancozeb and ethylenethiourea.

Mancozeb is a dithiocarbamate non-systemic agricultural fungicide with multi-site, protective action. It helps to control many fungal diseases in a wide range of field crops, fruits, nuts, vegetables, and ornamental plants. We have investigated the stability profiles of mancozeb in aqueous solutions to determine the effect of pH, temperature and light on the degradation process of mancozeb. In addition, the toxicological risk for humans associated with the joint intake of mancoze7b and its final degradation product, ethylenethiourea (ETU), was calculated and modelled as a function of the experimental conditions. Stability study results showed a very low stability profile of mancozeb in all the aqueous solutions with rapid degradation that varied with experimental conditions. The process followed first order kinetics. The study of the degradation kinetics showed a significant effect of pH*temperature interaction on the degradation process. The results also expressed that light has a greater impact on the stability of mancozeb and the formation of ETU. The current study concludes that mancozeb is unstable in aqueous solutions, particularly at an acid pH, in addition to presenting both severe light and lower temperature sensitivity. The toxicological risk associated with mancozeb degradation increases with time and temperature, being higher at basic pH and in absence of light.

Influence of the adjuvants in a commercial formulation of the fungicide "Switch" on the adsorption of their active ingredients: cyprodinil and fludioxonil, on soils devoted to vineyard.

The objective of this work was to assess the effect of adjuvants in the sorption in soils of the fungicides, cyprodinil and fludioxonil, usually applied together in a mixture commonly called 'Switch'. Water suspensions of a commercial formulation of Switch were used in phase partition experiments for a set of selected soils from vineyards. A clean-up procedure of the supernatant was developed for the phase separation in presence of the adjuvants prior to quantification of cyprodinil and fludioxonil. The maximum sorption on the solid phase (which includes soil and other solids from the commercial formulation of Switch) was 2000 mg kg(-1) for fludioxonil and 3000 mg kg(-1) for cyprodinil after incubation with 800 mg L(-1) of Switch. However, adsorption to soil particles were lower; fludioxonil concentrations adsorbed in soils range from 50 to 80 mg kg(-1) of soil and cyprodinil concentrations range from 120 to 260 mg kg(-1) of soil. Adjuvants increased the solubility of fludioxonil in pure water at 25 °C up to 5 times that of the pure substance (from 1.8 to 9 mg L(-1) in control samples), and show a strong influence on the adsorption in soil. Soil pH, effective cation exchange capacity and copper content due to past anti fungal copper-based sprays, have also influence on the adsorption of the active ingredients in presence of adjuvants.

Sorption of penconazole applied as a commercial water-oil emulsion in soils devoted to vineyards.

The objective of this work was to assess the effect of surfactants and oils of a commercial formulation on the potential mobility of penconazole in agricultural soils that have been subjected to a high rate of application of agricultural chemicals. Soil-water partition tests on a commercial water-oil emulsion formulation of penconazole (WOEP) in 0.01 M CaCl(2) containing 35 mg L(-1) penconazole, incubated for 24 h, showed a maximum retention of approximately 250-300 mg penconazole kg(-1) soil. Approximately 70% of the total penconazole retained by the solid phase was sorbed on the soil (175-200 mg kg(-1)). The other 30% was retained by the adjuvants present in the commercial formulation. The formulation also influenced the water-soil partition, increasing the sorption in tests on batch studies using technical-grade penconazole (TGP). Soils with high total copper and organic matter had the greatest affinity for penconazole when added as WOEP. Additionally, adsorption of penconazole followed an S-type isotherm, whose behavior was consistent with the ability of the technical-grade penconazole to form aggregates. In the case of the WOEP, the S-type behavior could be attributed to the surfactant present in the formulation, which could be adsorbed onto soil as hemimicelles, which in turn may facilitate adsorption of penconazole.

Behaviour of metalaxyl as copper oxychloride-metalaxyl commercial formulation vs. technical grade-metalaxyl in vineyards-devoted soils.

The objective of this work is to asses the sorption of metalaxyl applied as a copper oxychloride (CO)-metalaxyl formulation, for a set of selected soils devoted to vineyards. The method involved batch incubation of soils suspended with a commercial copper oxychloride-metalaxyl-based fungicide in 0.01M CaCl(2). Afterwards, the metalaxyl concentration remaining in solution was determined by high-performance liquid chromatography (HPLC). The amount of dissolved metalaxyl in the fungicide suspension depends mainly on the soil pH, its potential acidity, and the cation exchange capacity. Of the approx. 20% metalaxyl retained by the solid colloids, the effect of organic matter colloids in soils (15-20 mg kg(-1)) had a poor contribution (six times lower) than the copper oxychloride colloids (40%, w/w) in the commercial fungicide formulation (100-130 mg kg(-1)). When comparing these retention data with the behaviour of metalaxyl used as a technical grade fungicide of about 100% purity (10-15 mg kg(-1) in solids), it is clear that the commercial formulation increases a 30% retention of metalaxyl by soil (15-20 mg kg(-1) in solids). The overall effect of the metalaxyl formulation plus soil show values of 10 times higher retention than technical grade-metalaxyl plus soil. Commercial formulation can decrease the mobility of soluble metalaxyl in agricultural soils with regard to the expected values obtained from batch studies using analytical grade-metalaxyl. Therefore, the effect of surfactants should be considered in the assessment of water contamination by the pesticides used in agriculture.