Resistance of selected ornamental grasses to graminicides.
In greenhouse trials conducted during 1990, the effects of graminicidal resistance of selected ornamental grasses was evaluated. Festuca ovina var. glauca cv. Blue Glow, Sea Urchin and Spring Blue, and F. amethystina cv. Superba were resistant to fenoxaprop at 0.28 and 0.55 kg/ha, fluazifop-P at 0.21 and 0.42 kg, quizalofop at 0.11 and 0.22 kg, and sethoxydim at 0.32 and 0.64 kg, whereas Pennisetum alopecuroides, Erianthus ravennae and Panicum virgatum cv. Warrior were sensitive and showed 26-92% and 81-100% visible phytotoxicity at 14 and 69 d after treatment (DAT), resp. Minor (<20%) visible phytotoxicity was observed on some F. ovina cultivars treated with the 2-fold concn of fluazifop-P at 14 but not at 69 DAT. All herbicide treatments reduced shoot DW of E. ravennae, P. virgatum and P. alopecuroides at 28 DAT from untreated control values of 0.16-0.29 to 0 g, but the shoot DW of all F. ovina cultivars and F. amethystina were not affected by the herbicide treatments.