Giant hogweed (Heracleum mantegazzianum) has only been found once, in Kake, Alaska. If giant hogweed is found, report the location immediately. Giant hogweed looks similar to the native Heracleum sp., commonly called cow parsnip or pushke, and is distinguished by size and leaf form. Giant hogweed can reach 10-15 feet in height, with flowers that are up to 2 ½ feet across, and deeply divided leaves 3 to 5 feet wide. In contrast, cow parsnip or pushke is 4-6 feet tall with flowers up to 1 foot across, and lobed leaves up to 2 feet wide.

roadside distribution map hogweed AK — *Documented roadside occurrences of giant hogweed in Alaska. Data from the Alaska Exotic Plant Information Clearinghouse.*

Caution

Giant hogweed has toxic sap that can cause photosensitivity and chemical burns on skin. Do not allow any part of the plant or sap from cut plants to come into contact with skin. Always wear appropriate personal protective equipment: long sleeves, long pants, closed-toe shoes, gloves and safety glasses.

Manual

Digging plants up is effective if done before flowers produce seed, and if all the roots are removed. Dispose of flowers in plastic bags to prevent the spread of seeds.

Mowing

When mowed, giant hogweed will resprout from the main root crown. Long-term repetitive mowing is necessary to prevent flowering and starve the roots of nutrients.

Herbicides

Control with herbicides is effective for management. Herbicide control in Alaska is not documented. However, the Pacific Northwest Weed Management Handbook (http://pnwhandbooks.org/weed/) recommends products containing the active ingredients glyphosate or imazapic.

person standing under giant hogweed — *Giant hogweed grows 10-15 feet tall. Photo courtesy Alaska Division of Agriculture.*

giant hogweed vs cow parsnip — *Giant hogweed on the left and cow parsnip (aka pushke) on the right. Notice the deeply divided leaves of giant hogweed. Photo courtesy Alaska Division of Agriculture.*