Giant Hogweed (Giant Hogweed (Heracleum Heracleum mantegazzianummantegazzianum))

Life history, control and monitoring Life history, control and monitoring efforts. efforts.

By: The Nature ConservancyBy: The Nature Conservancy

Life HistoryLife History

• HabitatHabitat• Ravines, roadsides, ditches and riparian areas. Ravines, roadsides, ditches and riparian areas. • Residential properties and vacant lots. Residential properties and vacant lots. • Wooded or open space areas between residential Wooded or open space areas between residential

communities.communities.

Morphology

• Height: 8 – 15ft when in flower• Leaves: large, compound,

deeply incised, and 3 – 5ft wide. Hairs on the underside are stiff, dense, and stubby but only about .25mm long.

• Petioles have short course white hairs at the base.

• Flower head: Flat topped, up to 2.5ft across.

• Seeds mature in August, distributed summer/fall (water, wind, mowers)

Similar species

• Picture!

Cow Parsnip

Cow Parsnip

Angelica

SafetySafety

• Extreme skin hazard! Extreme skin hazard!

• Eye exposure can lead to temporary or Eye exposure can lead to temporary or permanent loss of vision. permanent loss of vision.

• If exposure does occur wash skin with If exposure does occur wash skin with soap and water, avoid the sun, and seek soap and water, avoid the sun, and seek medical attention. medical attention.

• When working with plants cover all parts of When working with plants cover all parts of the body. the body.

Control

• Difficult to control due to photo-toxicity. (ie. Contact with plants sap and exposure to UV light will cause severe blistering)

• Hand-digging• Repeated mowing, weakens

plant but large roots will remain alive for years.

• Herbicide sprays, a foliar treatment of glyphosate or triclopyr. (Has been effective in the Pacific Northwest).

Monitoring

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Mathis Rd

Mud Lake Rd

47

West Leyden

Giant Hogweed Locations in Town of Lewis

0 1,100 2,200 3,300 4,400550Meters

.Legend

! Giant Hogweed

lewis

publiclands

Towns

Other sightings?