Japanese knotweed is a terrestrial invasive plant that is well established in the Adirondacks. Plants spread rapidly and invade roadsides, stream banks, and disturbed locations. This herbaceous perennial shrub has leathery, heart shaped leaves, cascading white flowers that bloom in August, and notched, hollow stems.

RIIPP contracts with certified pesticide applicators to treat invasive knotweed on public and private land. Landowners battling Japanese knotweed can sign an indemnity form that gives applicators permission to treat plants on private property with a stem injection or foliar spray of glyphosate herbicide.

Stem injection treatment of Japanese knotweed occurs in August and September when plants are in bloom and carry nutrients and herbicide to the roots, effectively killing the plant. Some canes may be missed during the first stem injection treatment, and regrowth may occur. Any remaining small plants are treated with a foliar spray. Full eradication may take several years.

Japanese knotweed management is tricky because digging and cutting can spread the plant. New plants can sprout from broken root and stem fragments.

Japanese knotweed is an invasive shrub with leathery, heart shaped leaves, cascading white flowers that bloom in August, and notched, hollow stems. (Provided photo — Hamilton County Soil and Water Conservation District)

While there is no cost to landowners who wish to have Japanese knotweed treated by a certified applicator, donations are strongly encouraged to fund the program and elevate the priority of the property owner’s indemnity form. RIIPP has little overhead as all donations and funds directly pay the applicators. Infestations near lakes and streams are also a high priority.

“Thanks to the grassroots efforts of RIIPP, hundreds of thousands of Japanese knotweed canes have been treated, with successful eradication at some sites,” said Caitlin Stewart, manager of the Hamilton County Soil and Water Conservation District. “A DEC (state Department of Environmental Conservation) grant that supported the program concludes at the end of this year, and donations are needed to continue to fuel knotweed management efforts. Municipalities, organizations and individuals can make a tax-deductible donation payable to Hamilton County SWCD-RIIPP, and mail to P.O. Box 166, Lake Pleasant, NY 12108.”

RIIPP was established in 2008 by a group of concerned citizens led by Douglas Johnson, summer resident of Seventh Lake, and state and local agencies to address the Japanese knotweed explosion in Inlet and throughout the Adirondacks. At that time, the town of Inlet took the lead to manage the program. Since 2015, the Hamilton County Soil and Water Conservation District has coordinated RIIPP.

Partners include the DEC, state Department of Transportation, Adirondack Park Invasive Plant Program, Hamilton County Department of Public Works, town highway departments, Adirondack Watershed Institute and volunteer landowners.

“I am grateful for the financial contributions that RIIPP receives that support the continued management of invasive plants in the Adirondacks, as well as the steadfast dedication from volunteers and partners,” Stewart said.

Hamilton County Soil and Water Conservation District technician Lenny Croote treats an aggressive stand of Japanese knotweed in Speculator. (Provided photo — Hamilton County Soil and Water Conservation District) (Correction: An earlier version of this caption had the incorrect name and location.)

RIIPP held its annual meeting on June 28 to review priorities and accomplishments. Volunteers and partners shared ideas and set action items. Efforts will further the program’s mission to eradicate invasive knotweed plants from all Adirondack Park lands.

Priorities for 2019 include re-treating knotweed on private lands as needed to combat re-growth, obtaining indemnity forms for new sites to treat knotweed as time and funds allow, and treating wild parsnip along right-of-ways.

In 2018, certified applicators treated over 251 knotweed sites in 28 communities across the Adirondacks. They spent 526 hours injecting over 20,742 knotweed canes and spraying 35,000 knotweed plants. At least 52 sites that were treated in the past showed no knotweed regrowth. Applicators also spent 50 hours treating 26 sites of wild parsnip along roadsides.

Indemnity forms, and more information about RIIPP, Japanese knotweed and wild parsnip are available at www.noknotweed.org.

The Hamilton County Soil and Water Conservation District has been working to manage the use of natural resources since 1965. For more information, go to www.hcswcd.com or call 518-548-3991.

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This article is a press release written by the Hamilton County Soil and Water Conservation District, based in Lake Pleasant.