Methiozolin sorption and mobility in sand-based root zones

Background: Methiozolin is a herbicide currently used for annual bluegrass control in golf course putting greens. Previous research indicates that maximum weed control efficacy requires root exposure; however, soil sorption and mobility of methiozolin have not been established. Research was conducted to investigate soil sorption and subsequent desorption by dilution of methiozolin, as well as soil mobility using batch equilibrium experiments and thin-layer chromatography in nine root zones. Evaluations focused on sand-based systems typical of many golf course putting greens.

Results: Sorption coefficients (Kd values) ranged from 0.4 to 29.4 mL g(-1) and averaged 13.8 mL g(-1) . Sorption was most influenced by organic matter content; conversely, soil pH had a negligible effect. Methiozolin desorption did not occur with a 0.01 M CaCl2 dilution. Methiozolin mobility was low; retardation factors (Rf values) were <0.05 for all media with ≥0.3% organic matter. Sand (0.1% organic matter) resulted in an Rf value of 0.46.

Conclusion: Approximately 24% of applied methiozolin is available for root uptake, and mobility is limited, suggesting resistance to loss through leaching displacement.