Its October, and that means its time for a new Weed of the Month!
We are working with our partners at the Columbia Gorge Cooperative Weed Management Area to promote invasive Italian arum (Arum italicum) as our weed-of-the-month for October.
Italian Arum, also known as “orange candleflower” and “Italian lords and ladies,” is a non-native perennial that was introduced as an ornamental plant. It has now naturalized and appears to be spreading. Arum italicum is a woodland species and prefers moist, well-shaded environments. It’s extremely difficult to eradicate once it becomes established and may spread from residential gardens into woodland areas.
Italian arum produces an abundance of variegated green and white leaves. The plant is 12” to 18” tall with arrowhead shaped leaves that are 8” to 12” long. They emerge in the spring from underground corms but die back in the summer. Pale hood like flowers are produced in late May and give off a displeasing odor. Berries are formed in tight clusters and change color from light green to orange red.
This plant is problematic because of its ability to form a dense cover in open sites. It can out-compete native plants and prevent their establishment. Italian arum is also toxic to humans and animals. All parts of Italian arum are poisonous. Handling of the plant can cause skin irritation and ingestion can cause swelling of the mouth, tongue and throat. Breathing difficulties can follow as well as burning pain and stomach upset.
One of the best ways to control this plant is to prevent its spread. Often, chemical control only burns back foliage and does not hurt the corms (like bulbs) underground. Digging and disposing of the small underground corms in the garbage can help. However, manual removal is only recommended on small patches, because if the plant is not completely eradicated, the soil disturbance can increase its spread. If you have it on your land, do not let it go to seed. Wearing gloves, cut and bag all seed heads, and dispose of them in the garbage. For information about control, contact your local, Weed Distrit, Soil and Water Conservation District, or County Extension Office.
This plant is still commercially available, but landowners and producers are advised to avoid planting this invasive weed. As such it may be still be found in some residential gardens. If a landowner in Clackamas County believes he or she has Italian arum, please report it to the Oregon Invasives Hotline at www.oregoninvasiveshotline.org. For more information about Italian arum visit the Columbia Gorge Cooperative Weed Management Area website at www.columbiagorgecwma.org.