Landscape Management, Weed Watch 2014
WEEDWATCH STANDING SENTINEL TO PROTECT PLANT HEALTH BULL THISTLE Cirsium vulgare IDENTIFICATION TIPS This invasive noxious biennial can form large infestations especially along trails roads and vacant elds Plants grow erect with spines on the leaves and stems Arranged alternately on the lowering stem leaves are lanceolate with deeply cut margins They are coarsely hairy on the upper side and contain softer whitish hairs below Rose to reddish purple lowers grow at the ends YELLOW WOODSORREL Oxalis stricta L For more information regarding these and other turf weeds and related control technologies and tips please visit www DowProvesIt com or call 800 255 3726 BROUGHT TO YOU BY PHOTOS BY DR SHAWN ASKEW FAR LEFT DR RONALD CALHOUN Recommended Dow AgroSciences solution Dimension specialty herbicide Recommended Dow AgroSciences solution Lontrel specialty herbicide of the branches surrounded by spiny tipped bracts CONTROL TIPS The invasive nature of this weed dictates early detection and control It reproduces only by seed so application prior to seed set is most effective For optimum control apply a post emergent herbicide containing clopyralid in fall or early spring when the thistle is in the seedling to rosette stage State restrictions on the sale and use of Dimension and Lontrel apply IDENTIFICATION TIPS This perennial weed is commonly found in greenhouses ornamentals and turfgrass Leaves are divided into three heart shaped lealets with small yellow lowers The presence of underground rhizomes helps distinguish yellow woodsorrel from creeping red woodsorrel Oxalis corniculata where the stolons are above ground Five petal lowers occur in clusters that grow from long stalks at the leaf axils CONTROL TIPS This weed is most effectively controlled by appropriately labeled pre emergent herbicides In container and landscape settings products containing dithiopyr or isoxaben provide excellent control Yellow woodsorrel is not easily controlled by post emergent herbicides Two three or four way herbicide mixes provide minimal postemergent control 25 NOVEMBER 2011 LANDSCAPEMANAGEMENT NET
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