Methiozolin is an excellent candidate for annual bluegrass management in turfgrasses.

Methiozolin is a new turf herbicide controlling annual bluegrass in various cool- and warm-season turfgrasses. This study was conducted to investigate the fate of methiozolin in soil under aerobic and anaerobic flooded conditions using two radiolabeled tracers, [benzyl-(14)C]- and [isoxazole-(14)C]methiozolin. The mass balance of applied radioactivity ranged from 91.7 to 104.5% in both soil conditions. In the soil under the aerobic condition, [(14)C]methiozolin degraded with time to remain by 17.9 and 15.9% of the applied in soil at 120 days after treatment (DAT). [(14)C]Carbon dioxide and the nonextractable radioactivity increased as the soil aged to reach up to 41.5 and 35.7% for [benzyl-(14)C]methiozolin at 120 DAT, respectively, but 36.1 and 39.8% for [isoxazole-(14)C]methiozolin, respectively, during the same period. The nonextractable residue was associated more with humin and fulvic acid fractions under the aerobic condition. No significant volatile products or metabolites were detected during this study. The half-life of [(14)C]methiozolin was approximately 49 days in the soil under the aerobic condition; however, it could not be estimated in the soil under the anaerobic flooded condition because [(14)C]methiozolin degradation was limited. On the basis of these results, methiozolin is considered to undergo fast degradation by aerobic microbes, but not by anaerobic microbes in soil.

To elucidate the fate of a new sulfonylurea herbicide, LGC-42153 [N-((4,6-dimethoxypyrimidin-2-yl)aminocarbonyl)-2-(1-methoxyacetoxy-2-fluoropropyl)-3-pyridinesulfonamide], in soil, an aerobic soil metabolism study was carried out for 120 days with [(14)C]LGC-42153 applied to a loamy soil. The material balance ranged from 90.7 to 101.5% of applied herbicide. The half-life of [(14)C]LGC-42153 was calculated to be approximately 9.0 days. The degradation products resulted from the cleavage of the sulfonylurea bridge. The metabolites identified during the study were N-((4,6-dimethoxypyrimidin-2-yl)aminocarbonyl)-2-(1-hydroxy-2-fluoropropyl)-3-pyridinesulfonamide, 2-(1-hydroxy-2-fluoropropyl)-3-pyridinesulfonamide, and 4,6-dimethoxy-2-aminopyrimidine. No significant volatile products or [(14)C]carbon dioxide was observed during the study. Nonextractable (14)C-residue reached 14.4-30.5% of applied material at 120 days after treatment, and radioactivity was distributed mostly in the humin and fulvic acid fractions.

-5-methyl-3-(3-methyl-thiophen-2-yl)-4,5-dihydro-isoxazole) is a new turf herbicide in isoxazoline chemistry. The herbicide controls grass weeds and has a high safety to various cool and warm season turfgrasses. This paper describes basic chemical, biological, and regulatory information of methiozolin.

Methiozolin [5-(2,6-difluorobenzyl)oxymethyl-5-methyl-3-(3-methylthiophen-2-yl)-1,2-isoxazoline] is a new turf herbicide that controls annual bluegrass in various cool- and warm-season turfgrasses. The present study is the first report elucidating absorption, tissue distribution, excretion, and metabolism of methiozolin in rats. The pharmacokinetic parameters in the blood were observed as follows: t(max) = 6 h, C(max) = 168.7 μg equiv/mL, t(½) = 49.4 h, AUC₁₂₀ = 9921.5 μg equiv·h/mL, and clearance = 39.2 mL/h/kg. Those parameters and the depletion curve for ¹⁴C in the plasma were very similar to those in the blood. Total excretion through urine and feces was 24.3 and 68.9%, respectively, during 120 h after administration; however, there was no excretion through expired air. The radioactivity excreted through bile was 40.1% of that administered. Excreted radioactivity peaked between 24 and 48 h, showing 51.0% of total excretion within 48 h. The orally administered ¹⁴C distributed across various tissues within 12 h after administration, showing 14.0% of the dosed, and was eliminated from all tissues without accumulation. Numerous minor metabolites (<4% of the dosed) in urine and fecal extract were detected within 72 h, and two of those were identified. The identified metabolites were Met-1 (glucuronic acid conjugate), 6-[5-(5-((2,6-difluorobenzyloxy)methyl)-4,5-dihydro-5-methylisoxazol-3-yl)-4-methylthiophen-2-yloxy]-tetrahydro-3,4,5-trihydroxy-2H-pyran-2-carboxylic acid, and Met-2, [2-(5-((2,6-difluorobenzyloxy)methyl)-4,5-dihydro-5-methylisoxazol-3-yl)thiophen-3-yl]methanol. Conclusively, methiozolin was shown to be readily absorbed in the gastrointestinal tract, distributed throughout the tissues within 12 h, metabolized extensively, and eliminated through urine and feces mostly within 48 h, without tissue accumulation.