Invasive plant experts battling potentially dangerous ‘giant’


MANITOWOC – Looking for: riverfront property, a little bit of shade; Likes: crowding out native plants.

If Giant Hogweed took out a personals ad, Schuette Park, situated along the Manitowoc River in Manitowoc, might be its match.

“About a week ago, somebody showed me a picture, it hadn’t headed out yet, and it looked very suspicious,” said invasive plant specialist and former Manitowoc County Soil and Water Conservation Department Director Tom Ward, “It’s good to have it checked out.”

Reports of the invasive plant popping up in the park prompted Ward to head to the park on a blind date.

“They’re very similar,” said Ward of the suspected plant that turned out to be Cow Parsnip, a native plant. Not the Giant Hogweed, which has been found in Manitowoc County, as well as Waupaca and Iron Counties.

The two come from the same family – the carrot family. However, Giant Hogweed is native to Asia and can sometimes grow to 20 feet tall.

Ward says the sap of both plants is something you don’t want to mess with.

“The sap of either one of these plants – Hogweed or Cow Parsnip – is very photosynthetic and photo-reactive.”

That means when the sap reacts with bare skin when exposed to sunlight. It can cause burn-like blisters, potentially cause blindness when eye contact is left untreated and the symptoms can persist for several years after exposure.

Ward says it’s fairly common for people to mistake Cow Parsnip and its white, flowering head, and the much larger, also white, flowering head of the Giant Hogweed.

Ward says one of the biggest problems is Giant Hogweed is often found on private property, partly because property owners don’t know it’s there or don’t know that it’s a problem.”

“We’ve got a week or two and this will turn to a seed,” said Ward after changing locations to a homestead, east of Kiel, in the Town of Schleswig in Manitowoc County. Ward’s been treating the Giant Hogweed problem there for the past five years.

“This is just the summer’s growth,” said Ward, standing next to the seven-foot-plus plant. “That’s how fast this thing grows.”

Ward says other ways to tell Giant Hogweed apart from other similar plants by its large, purplish stalk, and broad, spiked leaves roughly two feet in length.

It’s this time of year the plants are most visible. Which is Ward says people should be aware of the problem and be ready to deal with the plant.

“But I would be wearing rubber gloves and definitely a face shield. Not just goggles, but a face shield.”

Ward says if you suspect you have Giant Hogweed, to figure out if it’s Cow Parsnip first, before contacting the DNR or another invasive species specialist for removal help.

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