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The increasing global reliance on pesticides for agricultural pest control has raised significant environmental concerns, particularly due to inadequate monitoring of emerging chemicals in surface waters. This study addresses the potential contamination of aquatic ecosystems by developing and validating a method for detecting trace amounts of four recently registered fungicides: three succinate dehydrogenase inhibitors (fluopyram, penthiopyrad, pydiflumetofen) and fluopicolide, a structurally related fungicide. Employing QuEChERS-based sample extraction combined with ultra-high-performance liquid chromatography (UHPLC-MS-MS), this method achieves detection limits of 0.1 to 0.2 μg/L, with recovery rates between 90% and 110%, and intra-day relative standard deviation values well within the acceptable range of less than 20%. Applied to surface grab water samples from the greater Melbourne area, Australia, the method successfully identified all four fungicides at trace levels, including a notable high concentration of fluopyram (7.3 μg/L) during autumn, with the others intermittently detected at lower concentrations. This study represents the first documented instance of quantifiable detections of these four fungicides in Australian surface water systems. Given their high toxicity to several organisms and the limited global data on these substances, our findings underscore the critical need for continuous monitoring to inform strategies to safeguard aquatic ecosystems from these chemicals. [ABSTRACT FROM AUTHOR]

BACKGROUND For Corynespora cassiicola (Berk. & M.A. Curtis) C.T. Wei, a necrotrophic pathogen with a broad host range and a worldwide distribution, resistance to fluopyram has been attributed to mutations in SdhB/C/D subunit of the succinate dehydrogenase (SDH) complex. In our previous study, two point mutations in SdhB from isoleucine to valine at position 280 (I280V) and histidine to tyrosine at position 278 (H278Y) showed different resistance phenotypes to fluopyram and boscalid. This research was conducted to explore the correlation between the mutation of SdhB‐I280V or SdhB‐H278Y and resistance to fluopyram or boscalid and its effect on the fitness characteristics of C. cassiicola. RESULTS: The sdhB gene in a succinate dehydrogenase inhibitor (SDHI)‐sensitive C. cassiicola strain (wild type) was successfully replaced with the mutant sdhB gene (GTT at position 280, SdhB‐I280V) or with the mutant sdhB gene (TAC at position 278, SdhB‐H278Y,). Compared with the wild‐type strain, the replacement mutants exhibited significantly different resistance phenotypes, with SdhB‐V280 demonstrating moderate resistance to fluopyram and low resistance to boscalid, while SdhB‐Y278 was supersensitive to fluopyram and very highly resistant to boscalid. Both of the mutants exhibited decreased sensitivity to salt stress and increased SDH activity. These two mutations had no effect on the mycelial growth rate, sporulation ability, pathogenicity in vivo, sensitivity to osmotic stress and oxidative stress, cell wall damaging agents, or SHAM. CONCLUSION: Two adjacent mutations in the SdhB gene conferred different resistance phenotypes to SDHIs in C. cassiicola, which is important for the development of alternative antifungal fungicides and fluopyram resistance management. © 2021 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

ABSTRACT Succinate dehydrogenase inhibitor ( SDHI) fungicides constitute a relatively recent fungicide class registered for the treatment of grey mould on grapevine in Italy. The sensitivity profile to a novel compound fluopyram was established for a set of 203 Botrytis cinerea isolates collected from Sicilian vineyards within 2009-2012 prior its introduction into market. In addition, its performances were compared in in vitro and in vivo assays with other registered SDHI fungicide boscalid, to evaluate their frequency distributions EC50 values and cross-resistance patterns. Results of the article showed that EC50 values for fluopyram ranged from 0.05 to 1.98 µg mL−1. Although EC50 values of boscalid ranged from 0.01 to 89.52 µg mL−1, no cross-resistance relationship was observed between the two fungicides ( r = 0.003; P = 0.964) within our B. cinerea population. On further confirming these data, boscalid failed in controlling grey mould infections when boscalid-resistant isolates were inoculated on grape berries whereas fluopyram exhibited a good efficacy against the same isolates. This study represents the first report on the baseline sensitivity to fluopyram within B. cinerea population from Sicilian table grape vineyards in Italy, and it clearly shows the lack of cross-resistance in vitro and in vivo between fluopyram and boscalid for the field pathogen isolates. These results provided useful information for managing of fungicide resistance suggesting that fluopyram could be a valid alternative to boscalid for the control of grey mould of table grape. [ABSTRACT FROM AUTHOR]

Fluopyram is a succinate dehydrogenase inhibitor (SDHI) fungicide that is being evaluated as a seed treatment and infurrow spray at planting on row crops for management of fungal diseases and its effect on plant-parasitic nematodes. Currently, there are no data on nematode toxicity, nematode recovery, or effects on nematode infection for Meloidogyne incognita or Rotylenchulus reniformis after exposure to low concentrations of fluopyram. Nematode toxicity and recovery experiments were conducted in aqueous solutions of fluopyram, while root infection assays were conducted on tomato. Nematode paralysis was observed after 2 hr of exposure at 1.0 μg/ml fluopyram for both nematode species. Using an assay of nematode motility, 2-hr EC50 values of 5.18 and 12.99 mg/ml fluopyram were calculated for M. incognita and R. reniformis, respectively. Nematode recovery in motility was greater than 50% for M. incognita and R. reniformis 24 hr after nematodes were rinsed and removed from a 1-hr treatment of 5.18 and 12.99 μg/ml fluopyram, respectively. Nematode infection of tomato roots was reduced and inversely proportional to 1-hr treatments with water solutions of fluopyram at low concentrations, which ranged from 1.3 to 5.2 μg/ml for M. incognita and 3.3 to 13.0 μg/ml for R. reniformis. Though fluopyram is nematistatic, low concentrations of the fungicide were effective at reducing the ability of both nematode species to infect tomato roots. [ABSTRACT FROM AUTHOR]