Tolerance of Woody Nursery Stock to Classic (chlorimuron) and Harmony (thiameturon)

Abstract Classic and Harmony applied at rates ranging from 0.009 kg ai/ha (0.008 lb ai/A) to 0.067 kg/ha (0.06 lb/A) provided excellent preemergence and postemergence control of common groundsel (Senecio vulgaris L.) 5 weeks after application to container-grown nursery plants. Classic at 0.034 kg/ha (0.03 lb/A) and 0.067 kg/ha (0.06 lb/A) reduced yellow nutsedge (Cyperus esculentus L.) growth by 50 to 77% 5 weeks after preemergence or postemergence treatments. Harmony did not affect yellow nutsedge from either type of application. ‘Seagreen’ juniper (Juniperus chinensis L.), ‘Blue Pacific’ juniper (Juniperus conferta Parl.) and ‘Bennetts Compacta’ holly (Ilex crenata Thunb.) tolerated all rates of Classic and Harmony. ‘Girard's Rose’ (Rhododendron kaempferi Planch.) and ‘Coral Bells’ azale(Rhododendron obtusum (Lindl.) Planch.), and redtip photinia (Photinia × Fraseri Dress) were initially injured by these herbicides, but outgrew the foliar damage.