2024 Range & Pasture Western Rangeland Weed & Brush ID Guide

Biennial & Perennial Weeds

KNAPWEED: RUSSIAN Acroptilon repens Life Cycle: Biennial/Perennial Plant Description:

Herbaceous perennial, toxic to horses specifically. It reproduces from seed and vegetative root buds. Shoots, or stems, are erect, 18 to 36 inches tall, with many branches. Lower leaves are 2 to 4 inches long and deeply lobed. Upper leaves are smaller, generally with smooth margins, but can be slightly lobed. Shoots and leaves are covered with dense gray hairs. Flowers can be pink, lavender or white. Russian knapweed has vertical and horizontal roots that have a brown to black, scaly appearance, especially apparent near the crown. Russian knapweed is toxic to horses.

Treatment: Apply 16 fluid ounces of HighNoon ® herbicide per acre or apply Milestone ® herbicide at 5 to 7 fluid ounce per acre,

to plants in the spring and summer. Apply to plants from early bud to flowering stage and to dormant plants in the fall.

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