War on Weeds — Weeds are Everybody’s Problem
Turkish Thistle
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 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 one to five 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 are good options 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 documented 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.
Idaho is a wonderful place with awesome natural resources, landscapes, agriculture and recreational opportunities. Weeds threaten all the things that we love about Idaho. To detect, contain and control weeds in Idaho we have declared “War on Weeds.” These short articles are designed to give a brief description of each species, an explanation about why it’s a problem, insights into identification and Integrated Pest Management control options. — Justin Hatch
View or Download (pdf)
- Turkish thistle, 6-7
2024-2025 (pdf)
- Bur buttercup, 1-22
- Buckhorn plantain, 1-29
- Kochia, 2-5
- Feathered mosquito fern, 2-12
- Flowering rush, 2-17
- Jointed goatgrass, 2-24
- Giant hogweed, 3-2
- Hoary alyssum, 3-9
- Hydrilla, 3-16
- Giant knotweed, 3-23
- Johnsongrass, 3-30
- Quackgrass toms, 4-6
- Meadow hawkweed, 4-13
- Meadow knapweed, 4-20
- Mediterranean sage, 4-29
- Milium, 5-6
- Orange hawkweed, 5-11
- Parrotfeather milfoil, 5-24
- Perennial pepperweed, 6-1
- Dryer's woad, 6-8
- Purple starthistle, 6-29
- Saltcedar, 7-6
- Black Henbane, 7-24
- Scotch Broom, 8-3
- Squarrose knapweed, 8-10
- Syrian beancaper, 8-17
- Tall hawkweed, 10-5
- Water chestnut, 10-12
- Russian thistle, 10-19
- Musk thistle, 10-26
- Water hyacinth, 11-2
- Yellow devil hawkweed, 11-9
- Yellow flag iris, 11-16
- Eurasian watermilfoil, 11-23
- Yellow floating heart, 11-30
- Yellow starthistle, 12-7
- Phragmites, 12-14
- Common frogbit, 12-28
- Bittersweet nightshade, 1-4-25
- Diffuse knapweed, 1-11
- Russian knapweed, 2-12
- Spotted knapweed, 2-22
- Scotch thistle, 3-8
- White bryony, 3-15
- Canada thistle, 3-22
- Western salsify, 3-29
- Leafy spurge, 4-5
- Common burdock, 4-12
- Siberian elm, 4-19
- Field bindweed, 4-26
- Annual bluegrass, 5-17
- Large crabgrass, 5-24
- Congongrass, 5-31
- Turkish thistle, 6-7
Photo courtesy of Susan Langston, Bugwood.org.