The Invasives Strike Force, part of the Lower Hudson Partnership for Regional Invasive Species Management, is trying to eradicate poisonous giant hogweed from the Hudson Valley.

If Ryan Goolic McClean’s team runs out of time while tending to a giant hogweed site, he rearranges other work.

“I will reschedule a different project so we have enough time for giant hogweed,” he said. “Not only is it a natural concern and could crowd out native species, but the human health impact is a huge priority on a regional and statewide basis.”

McClean is the terrestrial invasive species project manager for the New York-New Jersey Trail Conference. As part of the Lower Hudson Partnership for Regional Invasive Species Management, he leads a team called the Invasives Strike Force crew. That team is tasked with on-the-ground management of invasive species threatening the ecosystems or posing a public health risk in the region. One of their earliest priorities each season is giant hogweed.

Giant hogweed is an invasive plant with an apt name — in its adult stage, it can be anywhere between eight and 14 feet tall. It has a green hollow stem that can be up to four inches across and has purple blotches and coarse white hairs that are particularly noticeable where the leaves attach to the stem. Its leaves, which can be up to five feet across, are lobed.

The plant, which is most populous west of Otsego County, appears to be eradicated from Albany County and is close to eliminated in Rensselaer County, thanks to a robust effort by the state Department of Environmental Conservation and partner organizations like the Capital Region Partnership for Regional Invasive Species Management (PRISM). In the Hudson Valley, where some infestations of the plant were so big they were incalculable, a mission to eradicate the plant is still underway. That effort is helmed by McClean. 

Beyond its size, the most identifiable characteristic of the plant is its flat-topped “umbrella,” or dome shape, of white flowers that can be up to 18 inches across. The plant typically flowers in June and July and can cause serious burns if it comes into contact with human skin, exacerbated by exposure to sunlight. (Examples of those burns can be seen on the DEC’s website, but a content warning for readers, the images may be considered graphic for some people.)

McClean’s goal, in partnership with the DEC, is the eradication of the plant in his region, which comprises Ulster, Dutchess, Orange, Putnam, Rockland and Westchester counties. 

As a terrestrial invasive species specialist, it’s McClean’s job to assess invasive plants and come up with eradication plans, which involve careful removal and management of plants. If he determines eradication isn’t in reach, as was the case with sapphire berry, management is discontinued. That won’t be happening anytime soon with giant hogweed. 

“I really think eradication is in reach,” he said. “It is one of our biggest success stories.” 

A map illustrating eradicated sites in the state shows that the plant has already been eliminated from Columbia and Westchester counties. Another map of active sites currently under monitoring or management shows that Dutchess County is the area within the Invasives Strike Force crew’s coverage zone with the most current activity. He attributes that to one very populous site that his team has made a lot of progress on. 

A map showing sites where giant hogweed is actively being managed across New York state.

When the site was discovered in 2019, McClean said the number of plants recorded was “too many to count.” By last year, the Invasives Strike Force crew had battled the hogweed down to 7,000 plants. This year, the team managed just over 1,100 plants on the site, McClean said.

Most managers don’t require their teams to count every plant, especially when there are 7,000 of them, but McClean is glad he did, because now he has the data to show their progress. “That’s nearly a seven-times reduction in giant hogweed, which is a huge, huge success.”

McClean says the key to management is early intervention: the plants need to be taken down before they flower and go to seed. An average plant produces 20,000 seeds, and those seeds can survive for years in the soil once they’re dispersed. For that reason, once all the plants from a site have been eliminated, McClean’s team still monitors the area for nine more years to make sure no new plants pop up. Only then is the site put in the “eradicated” category. 

A site in Dutchess County that was so thoroughly invaded by giant hogweed that the number of plants was “too many to count.”

The massive site in Dutchess County was in a big open field, which is likely why it went undetected long enough to grow so many plants they couldn’t be counted. Most of the intervention work McClean and his team do is on private property. Therein lie some of the obstacles they have yet to overcome: people.

“Landowner refusal for our crews to come and manage the hogweed is a problem we face,” he said. 

The reasons for people not wanting crews to intervene on their property vary. Some people like the plants and think that as long as they know not to touch the sap, it’s fine to have them, not realizing, or perhaps not caring, that if they go to seed, they can spread to other properties and pose risks to others. Others perceive McClean’s team as working for the government, and they don’t want the government intervening on their land. In other words, it’s politics.

“But I don’t care about politics,” says McClean. “All I care about is the giant hogweed.”

Another issue he faces is public education. In one instance, a person had received giant hogweed seeds from a gardening club and had planted the seeds in their garden, not knowing the health risks the plant posed. 

Public outreach, therefore, is one of McClean’s biggest tasks. If he becomes aware of a giant hogweed plant on private property and it isn’t the homeowner who called about it, he goes to all sorts of lengths to contact the person. He’ll call their house if he can find a number. Sometimes he takes to Facebook, Google and LinkedIn to try to find contact information. If all else fails, he’ll knock on their door, which he says people don’t always love. But he’ll take the awkward interactions. 

“Just because of how important this project is,” he said. 

Should you see giant hogweed, contact should be avoided. If you do come into physical contact with the plant, the affected area should be washed with soap and water immediately. The affected area should not be exposed to sunlight, as UV rays can exacerbate the effects. That also applies to the eyes — if you get the sap in your eyes, put sunglasses on and contact your doctor.

Medical attention is the most important thing to pursue if you come into contact with the plant. Afterward, or if you didn’t come into contact with it, contact the DEC by emailing ghogweed@dec.ny.gov; calling 845-256-3111, or texting 518-320-0309.

More information about how to identify giant hogweed can be found online. 

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