River to River Cooperative Weed Management Area

Sharing expertise and resources across jurisdictional boundaries

Karla Gage, River to River CWMA coordinator

Nestled between the Mississippi and Ohio Rivers, the River to River Cooperative Weed Management Area (CWMA) encompasses about 2.5 million acres in southern Illinois. The CWMA joins 13 federal and state agencies, organizations, and universities whose common goal is to coordinate efforts and programs on invasive plants across 11 counties in southern Illinois. 

“The CWMA was formally established in 2006 and is funded completely by grants,” explains Dr. Karla Gage, CWMA coordinator. “Our on-ground efforts are project-driven, so we identify the needs of our partners and write grants for funding to address those needs. To date we’ve raised more than $900,000 for various weed management projects.” These innovative projects, along with strong leadership, are proving successful for managing invasive plants in southern Illinois. 

The River to River CWMA targets 34 invasive plants for management including herbaceous species such as garlic mustard (Alliara petiolata), Chinese yam (Dioscorea oppositifolia), Japanese stiltgrass (Microstegium vimineum), and teasel (Dipsacus spp.); and woody species such as bush honeysuckle (Lonicera maackii), Japanese honeysuckle (L. japonica), kudzu (Pueraria lobata), tree-of-heaven (Ailanthus altissima), and Oriental bittersweet (Celastrus orbiculatus). Some of the invasive plants are relatively new invaders, while others like bush honeysuckle and autumn olive (Elaeagnus umbellata) are widespread. Management of these species is a combination of public awareness and education; on-ground control efforts within volunteers, strike teams, agencies, and private land managers; comprehensive surveys; and research and demonstration projects.


The private lands assistance program provides cost-share funding for invasive plant management. “We identify private landowners that need help managing priority invasive plants such as bush honeysuckle, and provide financial incentive for control,” explains Gage. “This program is non-regulatory and completely voluntary for landowners.” 

Funding for the private landowner program is from the US Forest Service State and Private Forestry, and US Fish and Wildlife Service - Wildlife and Sport Fish Restoration State Grant programs. Commercial contractors do most of the control work with 25 percent of the cost paid by the landowner and 75 percent by the grant program. Invasive plants targeted in the program are those that are considered major threats to conservation and have the potential to spread rapidly. 

Gage explains, “We believe that controlling these infestations on private lands will help landowners conserve the resources on their lands, and also benefit the region by removing a seed source and slowing the spread.” Although seven invasive plants are currently targeted in this program, other species can be included upon a situation-by-situation basis. 

The CWMA partners also recognized that having the right equipment can help the efficiency and success of any invasive plant project. To meet this need the CWMA has application equipment available for loan to private landowners living within the CWMA, or any conservation organization, Friends group, or land management agency. 


THE SOUTHERN ILLINOIS exotic plant strike team was modeled after the National Park Service strike team program, with a mission to monitor and control invasive plants within the CWMA. Pictured left, Bruce Henry, former Strike Team member.

Modeled after the National Park Service’s Exotic Plant Management Team, the Southern Illinois Exotic Plant Strike Team was developed in 2008 by The Nature Conservancy (TNC), in partnership with the Illinois Department of Natural Resources (IDNR), and the USDA Forest Service Northeast Area State and Private Forestry Program. Their mission is to monitor and control invasive plants within the River to River CWMA while keeping detailed management records. The team consists of two plant management specialists working under the guidance of The Nature Conservancy, IDNR biologists and the CWMA Coordinator. 

Invasive plants are prioritized for management based on their threat to high-quality natural areas and rare species; size of the target infestations; probability of successful control and potential for restoration; opportunities for public involvement; and commitment to follow-up monitoring and treatment. Applying an early detection and rapid response approach to invasive species management greatly improves the likelihood that invasions will be controlled while populations are still localized and containable. 

“The Strike Team has accomplished an amazing amount of work within the CWMA in the past four years,” reports Gage. “They typically work on IDNR natural areas and parks, with a smaller amount of time spent on federal lands.” 

>> Click to enlarge

In 2012, the Strike Team used herbicides, mechanical and manual removal to control 3,704 acres of 11 different nonnative invasive plant species. Using The Nature Conservancy’s Weed Information Management System (WIMS), comprehensive time and treatment records were recorded by the Strike Team and will be used to refine future operations and assess treatment success. 


The CWMA participates in a summer internship program sponsored by the Illinois Department of Natural Resources, Southern Illinois University Center for Ecology, Illinois Nature Preserves Commission, and the Illinois Clean Energy Community Foundation. This nine-week summer internship provides students with the opportunity to learn about invasive species management and research. 

“Our most recent spring semester intern, Austen Slone, used data collected from volunteers to develop a strategic control plan for bush honeysuckle in the Trail of Tears State Forest. He also worked on a project to determine which species of invasive plants are being sold online, and if so, whether the plant would be capable of surviving in southern Illinois. Both of these projects are very important for developing future management plans and priorities,” explains Gage. “This program not only helps us, but also gives students practical experience in managing invasive species.”  

Volunteers Misty Dodd and Jason Willand remove Japanese honeysuckle vines to release young trees in an oak restoration project at a Green Earth Inc. property (left), and Dan Stroh and Rob Stroh carry bags of garlic mustard removed during a control project (right).


One of the goals of the River to River CWMA is to educate and engage as many people as possible to help prevent introduction and spread of invasive plants in southern Illinois. 

“As part of the education process, the CWMA is in a unique position to identify and address knowledge gaps in practical invasive plant management that will benefit our partners and the public,” says Gage. Once a research need is identified, the CWMA often works with researchers at Southern Illinois University to develop a project.

COOPERATIVE RESEARCH. Southern Illinois graduate student Lindsay Shupert guides applicator Scott Flynn, research biologist with Dow Agrosciences, by pointing out corners of her sericea lespedeza research plots.

Lindsay Shupert, a graduate student with Dr. David Gibson at Southern Illinois University is conducting a research project on sericea lespedeza (Lespedeza cuneata) in the Crab Orchard National Wildlife Refuge. The objectives of her project are: (1) Measure the level of sericea lespedeza control and forb tolerance to varying rates of Garlon® 4 Ultra herbicide, and tank mixes of Garlon 4 Ultra herbicide and Vista® XRT herbicide applied in spring and fall; and (2) determine how supplemental seeding enhances restoration success following herbicide treatment. A split-plot design was used, where half of the treated plot received an early spring seeding of desirable prairie species, and the other half did not receive seeding. Field work is on-going and data analysis will be completed in spring 2014. 

Gage explains another research project proposed for 2013. “There is concern among land managers about the risk of exceeding the label application rate when controlling dense stands of woody invasive species with low-volume basal bark applications of Garlon 4 Ultra herbicide. Our new research project seeks to answer two questions: (1) At what stem densities of three woody invasive species (bush honeysuckle, autumn olive, and Oriental bittersweet) are managers at risk of going over the labeled application rate; and (2) Can this risk be minimized by reducing the rate of Garlon 4 Ultra herbicide and adding Milestone herbicide, thus maintaining a label application rate while still achieving optimal control?”

Showing the public firsthand the benefits of controlling invasive plants is also an important component of the program. At the popular Giant City State Park Visitors Center, a three-acre demonstration plot was established next to the Center, with an Illinois Wildlife Preservation Fund grant, to show successful management of invasive woody plants compared to a non-treated adjacent area. 

Scott Flynn, research biologist with Dow AgroSciences also worked with the CWMA to establish a demonstration site for management of woody species. “We established plots in the summer of 2012 to demonstrate woody plant control. Low volume basal treatments included a 25 percent (%) solution of Garlon 4 Ultra in basal oil and a 20% solution of Garlon 4 Ultra plus 2% Milestone and 78% basal oil. Visual observations one year after treatment indicate excellent (95% or more) control of bush honeysuckle and autumn olive with both treatments. There was a noticeable decrease in the presence of Oriental bittersweet observed, but visual control was more difficult to determine for this species.” 


Partnerships developed through the River to River CWMA are providing a focused, organized effort in invasive species control at the local and regional scale. The CWMA facilitates projects across borders between townships, counties, federal, state, and private lands. 

Gage explains her thoughts on the future of the CWMA. “Because of the rich biological diversity of the region, there are many concerned stakeholders in the conservation effort. Education and outreach is a critical component of the CWMA, and even more emphasis on this is needed—greater outreach, mobilizing more volunteers and training more individuals to recognize invasive species. We believe the greatest successes in invasive species control will be built upon public education. It is critical that individuals learn to appreciate native ecosystem so they fully understand the importance of controlling invasive plants and preventing the introduction of new invasive species.” 

Students from the Carbondale High School Environmental Club learn about invasive species from Karla Gage on Earth Day in the Park at Giant City State Park.

River to River CWMA Partners

  • Illinois Department of Agriculture

  • Illinois Department of Natural Resources

  • Illinois Department of Transportation

  • Shawnee Resource Conservation and Development Area, Inc.

  • Southern Illinois University at Carbondale

  • The Nature Conservancy

  • University of Illinois Extension

  • USDA Animal Plant Health Inspection Service

  • USDA Natural Resource Conservation Service

  • USFS Shawnee National Forest

  • USFWS Crab Orchard National Wildlife Refuge

  • USFWS Cypress Creek National Wildlife Refuge

  • USFWS Middle Mississippi River National Wildlife Refuge

CWMA Grant Funding Partners

  • USFS State and Private Forestry, Forest Health Protection Program

  • USFWS-WSFR State Wildlife Grant

  • IDNR Illinois Wildlife Preservation Fund grant programs

  • National Fish and Wildlife Foundation - Pulling Together Initiative

  • Boat U.S. Foundation

  • USDA Forest Service, Northeastern Area

  • National Forest Foundation

  • Illinois Department of Natural Resources’ C2000

Additional On-going River to River CWMA Projects

  • Partnership with the Central Hardwoods Invasive Plant Network (CHIP-N) on invasive plant survey

  • Mermet Lake Curly leaf Pondweed Eradication Program

  • Southern Illinois Database of Exotic Plant Occurrences

  • Volunteer Workdays

  • Aquatic Invasive Plant Boat Ramp Survey

  • Hydrilla Task Force and Hydrilla Hunt! Program

  • Illinois Invasive Plant Species Council

Those interested in forming a CWMA can download the “CWMA Cookbook: A Recipe for Success” at http://www.mipn.org/CWMACookbook2011.pdf. 

For additional information on the River to River CWMA contact Dr. Karla Gage at rtrcwma@gmail.com or go to http://www.rtrcwma.org/.


WOODY PLANT CONTROL IN NORTHERN PRAIRIES, an updated resource from TechLine, features recommendations, methods, and equipment for managing woody vegetation encroaching in northern prairies. Learn about foliar, basal, and cut surface applications as well as technical facts about herbicides used to manage woody plants. 

>> http://bit.ly/woodyplantcontrol


Herbicide products (active ingredients) mentioned in this article include Garlon 4 Ultra (triclopyr), Milestone (aminopyralid), and Vista XRT (fluroxypyr).

®™Trademark of Dow AgroSciences, DuPont or Pioneer and their affiliated companies or respective owners.

Milestone is not registered for sale or use in all states. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your state. When treating areas in and around roadside or utility rights-of-way that are or will be grazed, hayed or planted to forage, important label precautions apply regarding harvesting hay from treated sites, using manure from animals grazing on treated areas or rotating the treated area to sensitive crops. See the product label for details. State restrictions on the sale and use of Milestone apply. Consult the label before purchase or use for full details

State restrictions on the sale and use of Garlon 4 Ultra and Vista XRT apply. Consult the label before purchase or use for full details. Always read and follow label directions. ©2019 Corteva. 

Published September 2013; trademark updated June 2019.