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The Dirt | WEED TO WATCH: Italian Thistle

An infographic about identifying and controlling Italian Thistle (Carduus pycnocephalus), with images and weed management tips.

June 11, 2024

Italian thistle (Carduus pycnocephalus) is a winter annual that we’re finding in several types of habitat or land ownerships around Benton County. Italian thistle has the potential to take over pastures and colonize open, natural areas, threatening native habitat.  Bull thistle and Canada thistle have been prevalent in Benton County for years.  However, Italian thistle is a newer invader, and we urge land managers to be active in controlling this weed. If you have this weed, it’s likely in full bloom right now - use these tips to take care of it ASAP!

- When you find a new patch, dig it up!  This weed can be hand pulled with thick leather gloves when the soil is moist, but often using garden tools to dig it out works the best.

- Herbicide treatment in April and May before it fully flowers.

- Cutting off seed heads would be better than doing nothing, but digging and removing is much preferred.  Mowing is not recommended because of the risk of spreading seed.

- Throw debris in the garbage rather than compost/yard waste to prevent seeds from persisting through the compost process.

Check out the links below for more resources!