The possible cytotoxicity and genotoxicity assessment of indaziflam on HepG2 cells

The use of pesticides in farmland has increased considerably to protect crops against pests, weeds, and diseases. However, pesticides and/or their residues in ecosystems may affect non-target organisms. Indaziflam is a widely used herbicide in agricultural areas in the southern region of Turkey. Therefore, this study aimed to investigate the possible genotoxic and cytotoxic effects of indaziflam on HepG2 cells using comet assay, micronucleus assay, and xCELLigence. The HepG2 cells were treated with various concentrations of indaziflam for different duration of time based on xCELLigence results. Accordingly, the cells were incubated with indaziflam at final concentrations of 1, 5, 10, 20, 40, and 80 μg/mL for 96 h for cytotoxicity assay. To assess genotoxicity, cells were treated with indaziflam at final concentrations of 10, 40, and 100 μg/mL for 4 and 24 h. Ethanol was used as a solvent for indaziflam. Hydrogen peroxide (40 μM) was used as a positive control. Studies have revealed that indaziflam did not show a statistically cytotoxic effect at the tested doses. Nevertheless, genotoxicity studies showed that indaziflam induced both DNA strand breaks and micronucleus numbers depending on the exposure time and dose.

Annual bluegrass (Poa annua) resistance to indaziflam applied early-postemergence

BACKGROUND

Indaziflam is an alkylazine herbicide used to control annual bluegrass (Poa annua L.). Several locations in the southeastern USA reported poor annual bluegrass control following treatment with indaziflam during autumn 2015. A series of controlled environment experiments were conducted to confirm putative resistance to indaziflam in annual bluegrass collected from these field locations.

RESULTS

Indaziflam (25 g ha^-1 ) effectively controlled all putative-resistant annual bluegrass collections when applied preemergence (PRE), but was ineffective when applied early-postemergence (< 2.5 cm plant height; BBCH scale = 1; EPOST). In agarose-based plate assays, EPOST I₅₀ values for putative-resistant collections ranged from 2424 to 4305 pm compared with 633 pm for the herbicide-susceptible control; therefore, resistance indexes (R/S) ranged from 3.8 to 6.8. Resistant collections were not controlled by foramsulfuron, flumioxazin, glyphosate, glufosinate, metribuzin, pronamide, or simazine applied EPOST. Indaziflam content in herbicide-susceptible annual bluegrass was greater than a resistant collection from 0 to 10 days after treatment (DAT). Susceptibility was not restored when resistant collections were treated with indaziflam plus 1-aminobenzotriazole (10 mg L^-1 ), tebuconazole (1510 g ha^-1 ), or malathion (400 g ha^-1 ).

CONCLUSIONS

This is a first report of resistance to indaziflam in any plant. Additionally, we confirm that these annual bluegrass collections are resistant to several other herbicidal modes-of-action. It is unclear if this multi-herbicide resistance is due to a single resistance gene, multiple resistance genes, non-target site mechanisms, or a combination thereof. Additional research to better understand resistance mechanisms in these annual bluegrass collections is warranted. © 2020 Society of Chemical Industry.

Effects of Temperature on Seed Germination of Plantago lanceolata and Management in Carya illinoinensis Production

Plantago lanceolata L. (buckhorn plantain) is an encroaching winter weed described as one of the most successful noncultivated colonizing species around the world. Control of P. lanceolata in southeastern USA Carya illinoinensis (Wangenh.) K. Koch production has not been studied, nor has the role of temperature on germination using a thermal gradient table. Seed of P. lanceolata collected from a Georgia C. illinoinensis grove were tested for the effects of temperature over time to establish differences in effects on germination using a thermal gradient table. Temperatures ranged from 13.5 to 30.5 °C for 288 h. Cumulative P. lanceolata seed germination was 66% occurring at 17.8 °C at 242 h. Over the 288 h experiment, maximum P. lanceolata germination was 27% occurring at 17.0 °C, 187 h after initiation. Control of P. lanceolata with residual herbicides, or in combination with 2,4-dichlorophenoxyacetic acid (2,4-D) was evaluated in the interrow of C. illinoinensis groves containing Trifolium repens L., and in greenhouse experiments. Pre- and post-emergent herbicides included indaziflam, halosulfuron-methyl, and simazine applied alone, or in combination with 2,4-D in late autumn after P. lanceolata emergence in a C. illinoinensis grove. Indaziflam in combination with 2,4-D controlled P. lanceolata greater than 90% when applied in C. illinoinensis groves and greenhouse experiments. Halosulfuron-methyl and simazine applied alone, or in combination with 2,4-D, provided 67% or less P. lanceolata control in the grove experiments, and 83% or less in greenhouse experiments. Results suggested that herbicide applications should be made during the time when diurnal temperatures are between 15 and 30 °C, while abiding pre-harvest interval restrictions. Post- and pre-emergent herbicides may aid in controlling emerged weeds and reducing further weed emergence during the autumn of that year.

Simultaneous analysis of indaziflam and its metabolites in pitaya using dispersive solid phase extraction coupled with liquid chromatography coupled with tandem mass spectrometry

A simple and efficient multiresidue method using dispersive solid phase extraction and liquid chromatography coupled with tandem mass spectrometry was developed for the targeted analysis of indaziflam and its five metabolites (indaziflam-diaminotriazine, indaziflam-carboxylic acid, indaziflam-triazine indanone, indaziflam-hydroxyethyl, and indaziflam-olefin) in pitaya samples (including roots, plants, flowers, peels, pulp, and whole fruit). The analytes were extracted with acetonitrile, and the extracts were purified using multiwalled carbon nanotubes. The method was validated using pitaya samples spiked at 0.5, 5, and 50 µg/kg, and the average recoveries varied from 61.1 to 103.7% with relative standard deviations lower than 12.7% (n = 5). This method exhibited sufficient linearity within the concentration range of 0.1-100 µg/L. The limits of detection and quantification were in the ranges of 0.001-0.1 and 0.003-0.3 µg/kg, respectively. The method was successfully applied to analyze pitaya samples in Nanning, and no indaziflam or its metabolites were detected in the samples analyzed.

Method Development and Validation of Indaziflam and Its Five Metabolites in Soil, Water, and Fruits by Modified QuEChERS and UHPLC-MS/MS

A method for simultaneously determining indaziflam and its five metabolites in soil, water, and fruits using ultraperformance liquid chromatography/tandem mass spectrometry was established. The analytes were eluted in <4.5 min. Positive electrospray ionization mode was used. The analytes were extracted using acetonitrile containing 1% ammonium hydroxide, and then the extracts were purified using octadecylsilane and PRiME HLB cartridges. The quantification limits were 0.01-1.01 μg kg^-1. The linearities of the calibrations for all analytes were excellent ( R² > 0.9952). The recoveries at spike concentrations of 0.01, 0.1, and 1 mg kg^-1 were 81.3-112.1%. The intraday and interday relative standard deviations were <13.5% and <12.3%, respectively. The method was successfully used to determine indaziflam and its five metabolites in samples from markets and fields. The results confirmed that the method is an effective and robust procedure for routinely determining indaziflam and its metabolites in soil, water, and fruit samples.

Indaziflam: a new cellulose-biosynthesis-inhibiting herbicide provides long-term control of invasive winter annual grasses

BACKGROUND

Indaziflam is a cellulose-biosynthesis-inhibiting (CBI) herbicide that is a unique mode of action for resistance management and has broad spectrum activity at low application rates. This research further explores indaziflam's activity on monocotyledons and dicotyledons and evaluates indaziflam's potential for restoring non-crop sites infested with invasive winter annual grasses.

RESULTS

Treated Arabidopsis, downy brome, feral rye and kochia were all susceptible to indaziflam in a dose-dependent manner. We confirmed that indaziflam has increased activity on monocots (average GR₅₀  = 231 pm and 0.38 g AI ha^-1 ) at reduced concentrations compared with dicots (average GR₅₀  = 512 pm and 0.87 g AI ha^-1 ). Fluorescence microscopy confirmed common CBI symptomologies following indaziflam treatments, as well as aberrant root and cell morphology. Across five application timings, indaziflam treatments resulted in superior invasive winter annual grass control 2 years after treatment (from 84 ± 5.1% to 99 ± 0.5%) compared with imazapic (36% ± 1.2%). Indaziflam treatments significantly increased biomass and species richness of co-occurring species 2 years after treatment.

CONCLUSION

Indaziflam's increased activity on monocots could provide a new alternative management strategy for long-term control of multiple invasive winter annual grasses that invade >23 million ha of US rangeland. Indaziflam could potentially be used to eliminate the soil seed bank of these invasive grasses, reduce fine fuel accumulation and ultimately increase the competitiveness of perennial co-occuring species. © 2017 Society of Chemical Industry.

Influence of soil properties and soil moisture on the efficacy of indaziflam and flumioxazin on Kochia scoparia L

BACKGROUND

Kochia (Kochia scoparia L.) is a highly competitive, non-native weed found throughout the western United States. Flumioxazin and indaziflam are two broad-spectrum pre-emergence herbicides that can control kochia in a variety of crop and non-crop situations; however, under dry conditions, these herbicides sometimes fail to control this important weed. There is very little information describing the effect of soil properties and soil moisture on the efficacy of these herbicides.

RESULTS

Soil organic matter (SOM) explained the highest proportion of variability in predicting the herbicide dose required for 80% kochia growth reduction (GR₈₀ ) for flumioxazin and indaziflam (R² = 0.72 and 0.79 respectively). SOM had a greater impact on flumioxazin phytotoxicity compared to indaziflam. Flumioxazin and indaziflam kochia phytotoxicity was greatly reduced at soil water potentials below -200 kPa.

CONCLUSION

Kochia can germinate at soil moisture potentials below the moisture required for flumioxazin and indaziflam activation, which means that kochia control is greatly influenced by the complex interaction between soil physical properties and soil moisture. This research can be used to gain a better understanding of how and why some weeds, like kochia, are so difficult to manage even with herbicides that normally provide excellent control. © 2016 Society of Chemical Industry.

Influence of soil biochar aging on sorption of the herbicides MCPA, nicosulfuron, terbuthylazine, indaziflam, and fluoroethyldiaminotriazine

Sorption of four herbicides and a metabolite of indaziflam on a fresh macadamia nut biochar and biochars aged one or two years in soil was characterized. On fresh biochar, the sorption was terbuthylazine (Kd = 595) > indaziflam (Kd = 162) > MCPA (Kd = 7.5) > fluoroethyldiaminotriazine (Kd = 0.26) and nicosulfuron (Kd = 0). Biochar surface area increased with aging attributed to the loss of a surface film. This was also manifested in a decline in water extractable organic carbon with aging. Correspondingly, an increase in the aromaticity was observed. The higher surface area and porosity in aged biochar increased sorption of indaziflam (KdBC-2yr = 237) and fluoroethyldiaminotriazine (KdBC-1yr = 1.2 and KdBC-2yr = 3.0), but interestingly decreased sorption of terbuthylazine (KdBC-1yr = 312 and KdBC-2yr = 221) and MCPA (KdBC-1yr = 2 and KdBC-2yr = 2). These results will facilitate development of biochars for specific remediation purposes.