Japanese honeysuckle

In an effort to control the further spread of the invasive plant Japanese honeysuckle at Pere Marquette State Park, an aerial spray treatment operation was conducted at the park Nov. 12-13.

An aerial application contractor, utilizing a specially equipped helicopter with boom sprayers, applied an approved herbicide over carefully selected sections of the park, covering about 1,000 acres during the two days with weather conditions ideal for the application. Pere Marquette hiking trails and the Scenic Drive were closed to the public on those days while the aerial application was conducted. The herbicide used was based on a ratio recommended by the Department of Agriculture and chemical manufacturer, and it was combined with a substance to ensure that the herbicide would not drift from the targeted application area. 

The invasive and highly aggressive honeysuckle has taken over natural communities at the park. Honeysuckle, along with other invasive plants such as tree of heaven and Sericia lespedeza, can completely overwhelm naturally occurring plants and prove harmful to wildlife. These invasive plants do this by competing for resources (sunlight, water, nutrients) with native species. 

“As I am writing this on Nov. 18, 2020, visitors could drive through Scenic Drive at Pere Marquette and note that if they see green along the roadside, it’s honeysuckle,” Natural Resource Coordinator Kayla Alexander said. “There is a blanket of honeysuckle covering many areas.”

Honeysuckle is a particularly aggressive invasive species because the plant is active for a longer period than native bushes. Birds eat the plant’s berries and spread the seeds, adding to management challenges. The berries hold little nutritional value for the birds when compared to native berries. That is why Illinois DNR land managers are working to better control the spread of honeysuckle and other invasive plants. 


“At Pere Marquette State Park, we have more than 10,000 acres to manage and we are not able to devote as much time as we would like to eradicating honeysuckle,” Alexander said. “The aerial spraying effort was an effective option to help tackle this massive problem.” 

Honeysuckle aerial spraying requires coordination and needs to be done when weather conditions allow. Favorable conditions include no rain, no or little wind, and days that coordinate with the pilot’s schedule. 

“We look forward to seeing how successful aerial spraying was and have also set up control points that received no herbicide spray for comparison purposes,” Alexander said. "We will compare the control area to the areas that were sprayed and will adapt our land management strategies accordingly. For further information on areas sprayed or for specific questions, please feel free to call the park.” 

Alexander reminded visitors to check out virtual Bald Eagle Tours this winter and to start the passport to get a free t-shirt sponsored by the Alton Visitor Center. 

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