Scotch Thistle
Onopordum acanthium
Plants widely distributed in Utah. The current populations of these plants should be contained to halt their spread. These plants should not enter commercial channels.
Cost share may be available. This is one of our high priority weeds. See if you qualify for assistance.
Background
Scotch thistle is native to Europe and eastern Asia. It grows well in waste areas, pastures, rangeland, and along canal and stream banks.
Description
This biennial plant commonly grows 3 to 8 feet tall, but it may grow as high as 12 feet. Rosettes may be 4 feet wide. Large, spiny leaves are covered with dense hair, giving a grayish, blue-green coloration. Stems are winged. The flowers are violet to reddish with spine tipped bracts, blooming in mid-summer.
Control
Biocontrol research is currently being conducted. Herbicides can offer good-to-excellent control when applied between rosette and pre-bud stages.
