Tolerance of lilyturf (Liriope muscari) and four perennial ornamental grasses to preemergent herbicides

Abstract: Tolerance of field- and container-grown lilyturf (Liriope muscari (Decne.)), (Liliaceae) and four species of ornamental grasses (Poaceae), perennial quaking grass (Briza media L.), Japanese bloodgrass (Imperata cylindrica (L.) Beauv. 'Red Baron'), river oats (Chasmanthium latifolium (Michx.) Yates) and dwarf fountain grass (Pennisetum alopecuroides (L.) Spreng. 'Hameln'), to five preemergent herbicides (isoxaben, oryzalin, oxadiazon, oxyfluorfen, and prodiamine) was evaluated. Grasses were planted in the fall of 1997 and in the spring of 1998. Herbicides were applied to the fall planting in the spring of 1998. The April, 1998 plantings received herbicide applications within two or 45 days after planting. Herbicides were applied within two days of planting in May and June of 1998. All species in the field and containers were damaged most by oxyfluorfen, followed by oxadiazon; however, injury was not as severe with oxadiazon as with oxyfluorfen. The oxadiazon-treated plants recovered more quickly than oxyfluorfen-treated plants. Plants were least damaged by prodiamine, oryzalin, and isoxaben. Field-grown Japanese bloodgrass, dwarf fountain grass and lilyturf were generally less damaged when herbicide was applied in June, regardless of planting date or herbicide applied than by the April herbicide application. Prodiamine, oryzalin, or isoxaben caused few phototoxicity symptoms in the species tested, but oxyfluorfen and oxadiazon caused unacceptable injury.