Noxious weed expert warns of poison hemlock outbreak across Idaho

Wilder —The Idaho Weed Awareness Campaign says poison hemlock is spreading at an alarming rate this year across Idaho.

“We think it’s an escaped ornamental, a border flower that escaped from landscaping somewhere,” said Roger Batt of the Idaho Weed Awareness Campaign.

Just outside of Wilder, and throughout Idaho, vast stretches of Hemlock standing 7 feet tall crowd canal banks. The noxious weed is easy to spot because of its white flower.

Hemlock can grow up to 8 feet, its distinctive hairless stem is covered in purple spots. If swallowed, symptoms start within 20 minutes Symptoms include nervous trembling, salivation, dilation of the pupils, lack of coordination, rapid or weak pulse, respiratory paralysis, coma and eventually death. 

“Its one of the most toxic plants in the Western Hemisphere. It thrives near water so you’ll find it on canal banks and rivers banks. All parts of this plant are toxic. If eaten or any part of the juice gets on the skin or in the mouth, it’ll kill humans and animals, and it looks like parsley or dill,” said Batt.

Hemlock Originated in Europe and the ornate plant was originally brought to the United States for use as a border flower by landscapers according to the US Department of Agriculture. Experts say it’s a biennial plant because it takes two years to complete its life cycle.

Despite its toxicity, Batt says it’s easy to control the weed and with hand pulling and the use of herbicides like Round-up. But getting rid of weed is a lot of work.

“People should wear rubber gloves and protective clothing when pulling hemlock and they need to put the toxic plant into plastic garbage bags and trash cans,” said Batt.

He adds that when using herbicides to control the noxious weed, that farmers and gardeners should use approved herbicides. Batt says to always read the label and follow the safety instructions.

Farmers can also get help getting rid of poison hemlock and other noxious weeds from their canal banks by contacting their county weed superintendent at any of Idaho’s 44 counties, they can also get additional information by logging onto the Idaho Weed Awareness Campaign's website.