Indaziflam is a PRE herbicide for annual broadleaf and grass control in turfgrass systems and requires a 40-wk minimum interval between application and overseeding perennial ryegrass. Currently, activated-charcoal application is recommended to reduce that interval; however, preliminary evaluations determined activated charcoal alone was not a robust mitigation practice for successful establishment during perennial ryegrass overseeding. Field research was conducted in North Carolina and Tennessee to evaluate various mitigation practices to effectively overseed perennial ryegrass into indaziflam-treated turfgrass areas. Immediately following indaziflam application (53 g ai ha⁻¹), two scenarios were created by delivering 0 or 0.3 cm H₂O before mitigation practice. Irrigated plots were air-dried before conducting mitigation practices. Evaluated mitigation practices included scalping (0.6 cm cut height; debris removed), verticutting (1.25 cm depth; debris removed), and activated-charcoal application (167 kg ha⁻¹ applied as an aqueous slurry in 3,180 L ha⁻¹), evaluated individually and in each two-way combination in the order scalp followed by (fb) activated charcoal, scalp fb verticut, or verticut fb activated charcoal. Twenty-four hours after mitigation practice completion, perennial ryegrass was seeded (976 kg ha⁻¹) and maintained as a golf course fairway. Overall, perennial ryegrass cover was reduced ≥ 93% at 8 and 20 wk after treatment (WAT) when no mitigation practices were performed. Stand-alone mitigation practices variably improved perennial ryegrass establishment; however, no practice provided acceptable results for end users. Combining mitigation practices improved overseeding establishment, most notably by adding activated charcoal application or verticutting to scalping before irrigation. Across experimental runs and locations, scalp fb activated-charcoal application before irrigation reduced perennial ryegrass cover 22 to 27% at 20 WAT. Results from this research suggest mitigation practices in addition to the currently recommended activated-charcoal application should be performed by turfgrass managers to improve perennial ryegrass overseeding establishment in indaziflam-treated turfgrass areas.

Nomenclature: Indaziflam; bermudagrass, Cynodon dactylon (L.) Pers.; hybrid bermudagrass × African dogstooth grass, Cynodon dactylon (L.) × Cynodon transvaalensis Burtt Davy; perennial ryegrass, Lolium perenne L.

Indaziflam es un herbicida PRE para el control de gramíneas anuales en sistemas de céspedes y que requiere un intervalo mínimo de 40 semanas entre la aplicación y la siembra de Lolium perenne sobre césped bermuda establecido. Actualmente, la aplicación de carbón activado está recomendada para reducir este intervalo; sin embargo, evaluaciones preliminares permitieron determinar que el carbón activado solo no fue una práctica robusta para el establecimiento exitoso durante la siembra de L. perenne sobre césped establecido. Se realizó una investigación de campo en North Carolina y Tennessee para evaluar varias práctica de mitigación, para poder sembrar efectivamente L. perenne en áreas de césped tratadas con indaziflam. Inmediatamente después de la aplicación de indaziflam (53 g ai ha⁻¹), se crearon dos escenarios aplicando 0 ó 0.3 cm H₂O antes de la práctica de mitigación. Las parcelas irrigadas se dejaron secar al aire antes de realizar las prácticas de mitigación. Las prácticas de mitigación evaluadas incluyeron la remoción de la mayoría del tejido foliar (scalp; corte a 0.6 cm de altura y remoción de residuos), corte vertical (verticut; corte a 1.25 cm de profundidad y remoción de residuos), y la aplicación de carbón act