Public Works > Vegetation Management Resource Center > Maintenance

Aerial herbicide application attacks alien invaders

Pennsylvania's Lake Erie seashore, Presque Isle State Park, was closed to the public for a day in October 2012 to permit a helicopter to spray herbicide on invasive plants.

Publication date: January 7, 2013

By Leslie Drahos

Not since an unidentified flying object (UFO) was sighted at Pennsylvania's Presque Isle State Park in 1966 has an aerial event attracted so much attention at the popular Lake Erie peninsula.

But unlike the still-unsolved UFO incident, the sighting this fall was a commercial helicopter hired to spray herbicide on 170 acres of the park severely infested with phragmites (pronounced frag-mite-eez), Phragmites australis; and narrow-leaf cattail, Typha angustifolia. Both exotic plants dominate wetlands, forming dense monocultures that exclude native vegetation and permanently alter wildlife habitat.

"The biggest problem is phragmites," says assistant park manager Holly Best. "We have a lot of lagoons and inland waterways in the park. The plant is choking out those waterways and reducing habitat for resting and nesting water fowl and other bird species."

Situated along the Atlantic flyway bird migration route, Presque Isle hosts over 330 types of birds and more than 800 species of native plants, many of which are rare, threatened, or endangered. "Some are not found anywhere else in Pennsylvania, and others are not found anywhere else in this part of the U.S.," Best says.

A helicopter sprays herbicide on 170 acres of invasive plants at Presque Isle State Park along Pennsylvania's Lake Erie shoreline. Photo provided by Holly Best.

Island or Peninsula?

As the most popular destination along Pennsylvania's 65-mile Lake Erie shoreline—welcoming 4 million people a year—Presque Isle State Park is a 3,200-acre sandy peninsula that curves out into Lake Erie, forming a recurving sandspit continually reshaped by waves and weather. The park's seven-mile white-sand shoreline comprises 11 beaches.

Named by the French in the mid-1700s, Presque Isle translates to "almost an island." A Native-American legend that explains the shape of the sandspit tells of Eriez tribe members who ventured onto Lake Erie to find where the sun sets. When the spirit of the lake blew up a fierce storm to keep the intruders away from the sun, their god laid his outstretched arm into the lake to shield them from the tempest. His arm would remain in the lake, protecting the tribe's future generations.

The peninsula actually became an island four times in its history as waves eroded through the neck of the spit. Over the years, stabilization techniques to help sustain Presque Isle have included groins, seawalls, breakwaters, and beach nourishment, which means the replenishment of eroding sand.

An aerial image of Presque Isle resembles a giant floating frond of phragmites, an invasive plant destroying native habitat at the Pennsylvania state park located on Lake Erie.

Invasive Action Plan

Presque Isle State Park staff have been treating invasive plants on the ground since 1994, but 2012 is the first time aerial spraying has been used. "You get into these walls of phragmites that are about 12 feet tall and you can't treat them with just a backpack sprayer," Best says.

In 2010, the park received a two-year, $500,000 grant from Ducks Unlimited, which received the money from the National Fish and Wildlife Foundation. "As part of that project, we hired 10 interns to work on the ground using backpack sprayers and handheld cutting tools. We also have a tank sprayer that mounts on a utility vehicle or truck to treat larger areas."

The interns treated about 500 acres that contained small pockets of invasive plants. "Narrow-leaf cattail and phragmites were two of their targets, but they also sprayed other invasive plants," Best says. "We pretty much have every invasive plant in the park."

Ten interns were hired to treat small pockets of exotic noxious weeds with herbicide. Grant money for the project came from Ducks Unlimited, which received the money from the National Fish and Wildlife Foundation. Photo provided by Holly Best.

Future Growth Forecast

Best reports that in areas where park staff have treated invasives with herbicides and cutting strategies for years, and then maintained the resulting vegetation, rare plants have re-established themselves. "The concept is that the seeds are in the soil seed bank, and some remain viable for many years," Best says. "If we can get these exotic plants cut down and cleared off and get back to bare soil, the new growth will include some of the native plants, including some of the rare, threatened, and endangered species."

Presque Isle has used grant funding to create a volunteer corps called the Weed Warriors. "Every year when the new shoots come up, they will pull the sprouts so we can stop the phragmites from taking hold again," Best says.

In addition to utilizing the Ducks Unlimited funding, Best expects money for 2013 to come from the state and has requested funds from the Great Lakes Restoration Initiative for upcoming years. "But after those resources are gone, then this is going to be a problem," Best says. "You can't spray just once with a helicopter and think you are good to go. Continued maintenance is necessary."

Leslie Drahos is a freelance writer in Sagamore Hills, Ohio.