Turkish thistle (Carduus cinereus) is an annual native to Asia. It was first found in North America in 2007. Unfortunately, it has been found on the Idaho and Oregon sides of Hells Canyon. Little is known about how Turkish thistle, but we know that is can spread easily and that it can out compete native vegetation. It has been found mostly in canyon grasslands and on rocky slopes. 

 Turkish thistle can grow up to 4 feet tall and it has winged stems. Stems are loosely covered with soft wooly hairs and can be unbranched or openly branched. Basel leaves can be up to 4 inches long and have lobed edges. Stem leaves decrease in size towards the top of the stem. Flowers are purple and have a compressed appearance. Each stem can produce 1-5 flowers. Turkish thistle can easily be misidentified as Italian thistle or slenderflower thistle. It reproduces from seed and is not known to reproduce vegetatively. 

Integrated Pest Management (IPM) Options: 

• Prevention— Learn to identify this plant. Always clean equipment and clothing after leaving invested areas. 

• Mechanical— Digging and hand pulling is a good option for small infestations. Make sure to control prior to seed development. 

• Cultural—Establish healthy stands of beneficial vegetation that will compete with weed seedlings. Use grazing management practices that will encourage the growth of beneficial plants. 

• Chemical—Little is document about chemical control of Turkish thistle. Make sure to report any sightings to local authorities who can provide guidance on using chemical control methods.   Always read and follow herbicide label directions!

Justin Hatch, University of Idaho Extension Agriculture Educator in Caribou County. 208-547-3205
[email protected]