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Brendan Querion wades into a stand of Giant Hogweed. Photo: Brian Mann
Brendan Querion wades into a stand of Giant Hogweed. Photo: Brian Mann

Giant Hogweed is a plant invader that threatens people as much as ecoystems

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The last couple of decades, northern New York has been besieged by invasive plants and animals. The impact on the region's ecosystems has been profound. An invasive fungus called White Nose Syndrome has devastated once-thriving populations of bats. Zebra mussels and other non-native organisms are literally changing the chemistry of Lake Ontario and the St. Lawrence River.

For the most part, however, the foreign invaders haven't posed a threat to human health. But now, scientists, environmentalists and farmers are battling a nasty invasive plant from Eurasia called giant hogweed. As Brian Mann reports, the massive plant can cause serious injury and even blindness.

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Giant Hogweed can pose a serious health risk.  Photo: DEC

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Brian Mann
Adirondack Bureau Chief

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HEALTH ADVISORY:  If you think you may have found Giant Hogweed on your property, or on public land, email the Department of Environmental Conservation at or call the Giant Hogweed Hotline: 1-845-256-3111. Provide photos, detailed directions to the plant infestation and estimate the number of plants.

The day is sweltering as Brendan Quirion pulls on a lemon yellow hazmat suit, lime green rubber gloves and rubber boots. Even his eyes are covered by wrap-around sunglasses.

"This is the only plant where we’re this aggressive with our gear.  Most of the other plants don’t pose a human health hazard, so we don’t have to wear this protective clothing," he says. We’ve come to the edge of a hay field in Westport, in the Champlain Valley. Hidden down in a little ravine is a stand of massive plants: 10 or 11 feet tall, with huge white flowers. This is giant hogweed, and it’s nasty stuff.

"If you get in contact with the sap, it creates really bad blistering, 10 times worse than poison ivy. It can leave scarring for months and even years after the blistering goes away. So we recommend that people don’t even get close to this plant if they even suspect that it’s giant hogweed," said Quirion. He works for the Adirondack Park Invasive Plant Program, a project organized by the Adirondack Nature Conservancy that works in partnership with various state agencies and NGOs. He wades down in the midst of the Hogweed, which towers over him.  

"So the first thing we got to do is dispose of those seed heads, because we don’t want any more of those seeds to go into the ground and create more of a seed bank or spread further down the stream," said Quirion. He uses a long cutting tool to clip the flowers, tucking them one by one into a plastic garbage bag. It turns out there are some native plants that look sort of like Giant Hogweed; they’re not quite as tall, but they have similar white flowers and celery-like stalks.

According to Quirion, there are a couple of ways to identify an actual invader. He said, "Giant hogweed is the only one that has really defined red blotches on the stem, as well as coarse white bristles."

This is nervous work. Hogweed sap is so caustic that it can blind you if it gets in your eyes. After nearly an hour of meticulous pruning, Quirion’s face is bathed with sweat. He pauses and downs a bottle of water. "It’s super hot right now. Right now it’s probably close to 85 degrees and I’m in a hazmat suit that’s essentially like a giant garbage bag that I’m inside. So I’m sweating like crazy right now, my nose is dripping with sweat," said Quirion.

Still wrapped in his plastic suit, Quirion mixes a batch of herbicide on the tailgate of his truck. The use of chemicals in the fight against invasive plants still draws fire from some environmentalists, but Quirion says sometimes it’s a necessary tool. He said, "We always go with integrated pest management, which means that herbicide is the last resort. We’ve tried other options, whether it be cutting or biological control, and for some of these species it just doesn’t work.  And you just have to resort to herbicide use.  And so we’re really picking the lesser of two evils. If you think about an invasive plant that can completely take over a wetland, or if you’re just spraying those small individuals that are first starting to get rid of them, just think about how much you’re protecting with that small herbicide treatment."

Querion straps on a backpack tank and heads back down into the stand of hogweed. With his sprayer, he looks sort of like one of the guys in Ghostbusters, surrounded by these monster plants. In Western New York, Hogweed have exploded, taking over old farm fields and meadows. But here in the North Country, Querion says this is one invader that can be pushed back.

"Especially up here in the Adirondacks, I definitely think so. Seeing the results of our treatments in the other areas that we’ve been managing. We had 20 or 30 adult plants last year and when we went back there were five or six seedlings coming in. So I was encouraged by that. However, if people don’t become more aware of this issue, and they’re spreading it more and more, it is more difficult for us to keep up," said Quirion.

Giant Hogweed is another of those plants that was introduced to New York by gardeners who like the big leaves and the showy flowers. The good news is that now that it’s been added to the Federal government’s list of noxious plants, reputable greenhouses and gardening catalogues have dropped it from their lists.

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