This weed is taking over my yard

Asked February 1, 2018, 12:03 PM EST

Hi there, I’m taking the master gardening online course and for this week’s assignment I’m supposed to identify a plant and asking you folks to help is one of the ways to do it. I’m sending you a picture of this weed that is taking over my yard. It has a very deep tuberous root. We have tried to get rid of it by digging out the roots but that only seems to make it spread worse. Last year we merely pulled off the leaves and stems and that seemed an ok method of control, but as you can see it’s right back again and getting bigger all the time. Any help you can give beyond identification would be great too.

Benton County Oregon

1 Response

You have Italian Arum (Arum italicum). This is an extremely invasive plant that is very difficult to eradicate. It is also a noxious plant that can harm humans and mammals. When dealing with this plant you should always wear gloves and keep your hands away from your face and mouth. You should keep children and pets away from the plants too.

The only way to control this plant is manually. Digging out the bulbs, rhizomes, and root system needs to be thorough, removing even the smallest pieces of plant material. The removed soil needs to be placed in a plastic bag and discarded with your trash (do not put it in your compost).

Wearing gloves, you should remove blooms as soon as you see them. If you miss a bloom, remove the seed pod before it disperses the seeds, and dispose of it in a plastic bag, with your trash. See below photos of flower and fruit (seeds – green & red).

Various herbicides have been used to try and eradicate the plant with no success.

Here are two very good pamphlets that address the “Italian Arum”. One paper is from Washington State University and the second is from the City of Portland. Both papers stress that the “Italian Arum” is an extremely invasive plant that is almost impossible to eradicate and is poisonous and may cause death.

Thank you for submitting this question to "Ask an Expert"! Good Luck with your Master Gardener class.