Degradation of metalaxyl and folpet by filamentous fungi isolated from Portuguese (Alentejo) vineyard soils

Degradation of xenobiotics by microbial populations is a potential method to enhance the effectiveness of ex situ or in situ bioremediation. The purpose of this study was to evaluate the impact of repeated metalaxyl and folpet treatments on soil microbial communities and to select soil fungal strains able to degrade these fungicides. Results showed enhanced degradation of metalaxyl and folpet in vineyards soils submitted to repeated treatments with these fungicides. Indeed, the greatest degradation ability was observed in vineyard soil samples submitted to greater numbers of treatments. Respiration activities, as determined in the presence of selective antibiotics in soil suspensions amended with metalaxyl and folpet, showed that the fungal population was the microbiota community most active in the degradation process. Batch cultures performed with a progressive increase of fungicide concentrations allowed the selection of five tolerant fungal strains: Penicillium sp. 1 and Penicillium sp. 2, mycelia sterila 1 and 3, and Rhizopus stolonifer. Among these strains, mycelium sterila 3 and R. stolonifer presented only in vineyard soils treated with repeated application of these fungicides and showed tolerance >1,000 mg l−1 against commercial formulations of metalaxyl (10 %) plus folpet (40 %). Using specific methods for inducing sporulation, mycelium sterila 3 was identified as Gongronella sp. Because this fungus is rare, it was compared using csM13-polymerase chain reaction (PCR) with the two known species, Gongronella butleri and G. lacrispora. The high tolerance to metalaxyl and folpet shown by Gongronella sp. and R. stolonifer might be correlated with their degradation ability. Our results point out that selected strains have potential for the bioremediation of metalaxyl and folpet in polluted soil sites

The Effects of Copper Hydroxide, Captan and Trifloxystrobin Fungicides on Soil Phosphomonoesterase and Urease Activity

There is increasing community awareness of the potential environmental risks posed by Cu-based fungicide use, which is placing increasing pressure on governments and industry to undertake risk minimisation action. However, if there is going to be a widespread move away from the use of Cu-based fungicides, logically there needs to be assurance that the alternatives pose a lower environmental risk. To that end, this study compared the effect of copper hydroxide, captan and trifloxystrobin on soil enzymatic (phosphomonoesterase and urease) activity. Compared to an untreated control, copper did not inhibit either enzyme activity, even at the highest dose used in the study (156\ua0mg/kg). At their respective high doses, captan (96\ua0mg/kg) and trifloxystrobin (144\ua0mg/kg) did not cause inhibition of phosphomonoesterase activity but did inhibit urease activity. Consequently, the results from this study suggest that the copper hydroxide alternatives, captan and trifloxystrobin, do not pose a short-term risk to P cycling processes in soil, although the results do suggest that these two are more toxic than copper hydroxide to N cycling processes in soil. Moreover, captan and trifloxystrobin compounds are unlikely to pose a long-term risk to soil microbial function as they are unlikely to persist in soil at concentrations found to cause an adverse effect on urease activity. Nonetheless, the potential disruption to N cycling processes needs to be recognised and consideration given to limiting the annual applications of these fungicides, particularly around the timing of repeat fungicide applications, to prevent accumulation of the fungicides in surface soils

Intra-annual trends of fungicide residues in waters from vineyard areas in La Rioja region of northern Spain

The temporal trends of fungicides in surface and ground water in 90 samples, including both surface waters (12) and ground waters (78) from an extensive vineyard area located in La Rioja (Spain), were examined between September 2010 and September 2011. Fungicides are used in increasing amounts on vines in many countries, and they may reach the water resources. However, few data have been published on fungicides in waters, with herbicides being the most frequently monitored compounds. The presence, distribution and year-long evolution of 17 fungicides widely used in the region and a degradation product were evaluated in waters during four sampling campaigns. All the fungicides included in the study were detected at one or more of the points sampled during the four campaigns. Metalaxyl, its metabolite CGA-92370, penconazole and tebuconazole were the fungicides detected in the greatest number of samples, although myclobutanil, CGA-92370 and triadimenol were detected at the highest concentrations. The highest levels of individual fungicides were found in Rioja Alavesa, with concentrations of up to 25.52 g L1, and more than 40 % of the samples recorded a total concentration of >0.5 g L1. More than six fungicides were positively identified in a third of the ground and surface waters in all the sampling campaigns. There were no significant differences between the results obtained in the four sampling campaigns and corroborated a pattern of diffuse contamination from the use of fungicides. The results confirm that natural waters in the study area are extremely vulnerable to contamination by fungicides and highlight the need to implement strategies to prevent and control water contamination by these compounds. © 2016 Springer-Verlag Berlin Heidelber