Potted tropical ornamental tolerance to multiple PRE herbicides

Weeds are difficult to control in potted tropical ornamentals, especially when plants are kept for extended time periods at a nursery. Management is complicated by the lack of tolerance data for many tropical species. Experiments were conducted in 2015, 2016, and 2017 at the Gulf Coast Research and Education Center in Balm, FL, to evaluate tolerance of stromanthe, croton, philodendron, arbicola, cordyline, ixora, plumbago, allamanda, bird-of-paradise, firebush, and hibiscus to granular applications of indaziflam, flumioxazin, pendimethalin + oxyfluorfen, pendimethalin + dimethenamid-P, trifluralin + oxyfluorfen + isoxaben, and trifluralin + isoxaben, and liquid applications of prodiamine + isoxaben and dimethenamid-P. Indaziflam, pendimethalin + oxyfluorfen, and trifluralin + oxyfluorfen + isoxabin were safe for use on all evaluated ornamentals except stromanthe. Dimethenamid-P and pendimethalin + oxyfluorfen were safe on all evaluated ornamentals except allamanda. Flumioxazin damaged philodendron and bird-of-paradise but was safe on all other ornamentals tested. Trifluralin + isoxaben and prodiamine + isoxaben were safe on hibiscus, firebush, and bird-of-paradise, but prodiamine + isoxaben damaged allamanda. We have identified multiple PRE herbicides that can safely be used on multiple tropical ornamentals grown in containers. Nomenclature: Dimethenamid-P; flumioxazin; indaziflam; isoxaben; oxyfluorfen; pendimethalin; prodiamine; trifluralin; allamanda; Allamanda schottii Pohl.; arbicola; Schefflera arboricola (Hayata) Merr. ‘Trinette’; bird-of-paradise; Strelitzia reginae Aiton; cordyline; Cordyline fruticosa (L.) A. Chev. ‘Red Sister’; croton; Codiaeum variegatum (L.) A. Juss. ‘Mammy’; firebush; Hamelia patens Jacq.; hibiscus; Hibiscus rosa-sinensis L. ‘Painted Lady’; ixora; Ixora coccinea L. ‘Maui Red’; philodendron; Philodendron selloum K. Koch; plumbago; Plumbago auriculata Lam. ‘Dark Blue’; stromanthe; Stromanthe sanguinea Sond. ‘Triostar’.