Biennial & Perennial Weeds
THISTLE, SCOTCH Onopordum acanthium Life Cycle: Biennial Plant Description:
Plant grows up to 8 feet tall with branching, spiny leaf wings that extend down onto the stem and are covered with dense fine hairs. Leaves are large, closely
lobed, hairy on both sides and velvety gray in appearance. Leaf edges are lined with sharp spines. Basal leaves grow up to 2 feet long and 1 foot wide. Flowers are violet to reddish-colored, 1 to 2 inches in diameter. Treatment: Apply 16 to 20 fluid ounces of DuraCor ®
herbicide per acre or apply 1.5 to 2.1 pints of GrazonNext ® HL herbicide per acre. Apply in the spring and early summer to rosette or bolting plants or in the fall to seedlings and rosettes before the ground is frozen. Use higher rate after bolting through early flower.
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