Preemergence and Early Postemergence Control of Selected Container Nursery Weeds with BroadStar, OH2, and Snapshot TG1

Preemergence and early postemergence control of three common nursery weeds with BroadStar (flumioxazin), OH2 (oxyfluorfen + pendimethalin), and Snapshot TG (isoxaben + trifluralin) was compared in greenhouse and outdoor experiments. Hairy bittercress (Cardamine hirsuta), spotted spurge (Chamaesyce maculata), and common groundsel (Senecio vulgaris) were container-grown in the absence of ornamental crops and each herbicide was applied preemergence (labeled application) or postemergence to plants either at the cotyledon to one-leaf stage or at the two- to four -leaf stage. Each of the herbicides controlled hairy bittercress and spotted spur ge preemergence and when applied to plants at the cotyledon to one-leaf stage. The herbicides were less effective on hairy bittercress and spotted spurge at the two- to four-leaf stage, yet control was 60 to 89%. Common groundsel was controlled preemer gence by each herbicide; however, only BroadStar and OH2 controlled common groundsel ≥ 81% when applied at the cotyledon to one-leaf stage. No postemergence treatment controlled common groundsel when applied at the two- to four -leaf stage. Index words: container nursery crops; growth stage; herbicide; weed management. Species used in this study: hairy bittercress ( Cardamine hirsuta L.); spotted spurge (Chamaesyce maculata (L.) Small); common groundsel (Senecio vulgaris L.). Herbicides used in this study: BroadStar (flumioxazin), 2-(7-fluoro-3,4-dihydro-3-oxo-4-(2-propynyl)-2 H-1,4-benzoxazin-6-yl)-4,5,6,7- tetrahydro-1H -isoindole-1,3(2H)-dione; OH2, (oxyfluorfen), 2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl)benzene, plus (pendimethalin), N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine; Snapshot TG (isoxaben), N-(3-(1-ethyl-1-methylpropyl)-5- isoxazolyl)-2,6-dimethoxybenzamide, plus (trifluralin), 2,6-dinitro- N,N-dipropyl-4-(trifluoromethyl)benzenamine.