Project GREEEN-funded research packs a punch against problematic weeds

MSU scientists team up with Michigan plant industry groups using Project GREEEN and commodity dollars to combat weeds.

East Lansing, Mich. — For growers of any type of commodity or crop, the chance of weeds posing a threat to production is always present. However, having a collaborative network of plant commodity organizations, educators and researchers — fostered partly by Project GREEEN, Michigan’s plant agriculture initiative based at Michigan State University and supported by Michigan's Plant Coalition, the Michigan Department of Agriculture and Rural Development, MSU AgBioResearch and MSU Extension — has allowed industries to stay vigilant against the pesky plants that can disrupt growing seasons.

Project GREEEN, which is celebrating its 25th year in assisting Michigan’s vast diversity of plant industries, has helped scientists stay connected to current issues affecting industry professionals and growers. As they relate to weeds, some issues can trouble more than one industry. This makes collaboration that much easier.

“Some of our projects funded by Project GREEEN are more integrated, so the issues aren’t affecting just one industry,” said Christy Sprague, a professor and MSU Extension specialist of weed management in MSU’s Department of Plant, Soil and Microbial Sciences. “A lot of the time, we can pull commodity groups together and look at a wider overview of the issue. Those have been good collaborations.”

Christy Sprague, professor in MSU's Department of Plant, Soil and Microbial Sciences.

Project GREEEN has helped Sprague investigate weeds typically not seen in Michigan that have found their way into the state. Of those weeds, Palmer amaranth and common waterhemp remain highly important to control due to their rapid reproduction and growth rate, in addition to their resistance to herbicides.

Mark Seamon, research director of the Michigan Soybean Committee (MSC), said Project GREEEN funds have complemented funds from commodity groups like the MSC nicely to advance research into managing herbicide-resistant weeds. In soybeans, horseweed (marestail), along with common waterhemp, are hard-to-fight weeds Sprague has spent recent time addressing. 

“Through Project GREEEN, Dr. Sprague has proposed projects that address the most critical issues involving weed control in crops, with herbicide-resistant weeds probably being the number one concern in the state,” Seamon said. “These weeds are resistant to herbicides and don’t just stay on one farm — they’re shared with neighbors, and sometimes even a bit further. Dr. Sprague has done a great job studying which species are the most concerning and pose the greatest challenge to growers.”

Funds from both Project GREEEN and statewide commodity organizations have helped Sprague generate factsheets from conducted research that growers can use to implement mitigation strategies for weeds on their farms. In fact, Sprague said she and Erin Burns, an assistant professor of integrated weed management in MSU’s Department of Plant, Soil and Microbial Sciences, received Project GREEEN funding within the last year to redo and make more user-friendly the annual MSU Weed Control Guide.

“It’s a complete redesign,” Sprague said. “We’re excited about that.”

Sprague has also used Project GREEEN funds to examine the potential for carryover of winter wheat herbicides to cover crops. Cover crops are beneficial to farmers because they suppress weeds, restore nutrients and protect the soil from erosion. Like cash crops, they’re protected from weeds by herbicides.

However, in some cases, herbicides can remain in the soil and cause injury or death to the following crop — including cover crops. Herbicide carryover can limit the types of crops or cover crops that can be planted.  

“We were able to conduct this research at multiple locations because of Project GREEEN, which was really needed as growers begin including cover crops into their system,” Sprague said. “We need to be using herbicides while battling weeds, so we studied how winter wheat herbicides applied in the spring impact cover crops planted after winter wheat harvest.”

Beyond cover crops, this research is relevant for rotational crops, or different types of crops planted sequentially throughout a period of years to improve soil health. Jody Pollok-Newsom, executive director of the Michigan Wheat Program, said leveraging the program’s funds in conjunction with funds from Project GREEEN shows that the issues Sprague and other researchers devote their time and hard work to offer critical pieces of knowledge industries need to progress.


“If a problem is discovered and it’s decided that a larger, in-depth study needs to happen, that gives us at the Michigan Wheat Program a chance to do some partnering through Project GREEEN to make that happen,” Pollok-Newsom said. “One of the neat things about working with Dr. Sprague is that she goes to all the meetings and hears from growers as to what their challenges are.

“She came to us and said, ‘Herbicide carryover is one of the top questions I get from growers. I need to do research to get more information about what the effect is on wheat.’ That turned into a project we helped fund for multiple years.”

Through this project, Sprague has provided growers insight into several factors they should consider while using herbicides and planting rotational crops, including monitoring the time intervals different herbicides recommend growers follow for when an herbicide is applied and when a new crop is planted. In 2020, Sprague also produced a video using funds from the U.S. Department of Agriculture’s National Institute of Food and Agriculture, Project GREEEN and the Michigan Wheat Program to inform growers which herbicides they can use when planting cover crops.

Ornamental plants avail in fight against weeds from Project GREEEN funding

For Debalina Saha, an assistant professor in MSU’s Department of Horticulture, Project GREEEN has been a great tool in launching her research on weed control in ornamental crop production. After joining the department in 2019, she applied for and received funding in 2022 to study how weeds compete with ornamental plants growing in containers.

“Project GREEEN is a really good initiative, especially for new faculty members like me who are starting and developing new programs,” Saha said. “It’s helped me a lot. Grants for ornamental crops are quite limited, so it’s been good to have this kind of support to establish my program and help my graduate student complete his degree.”

In containers, weeds can reduce plant growth by up to 60%. For this project — funded through 2024 by Project GREEEN — Saha is studying how weed species such as large crabgrass and smooth pigweed compete with woody shrubs such as roses, spirea and syringa for space in potted containers, and how controlled-release fertilizer placements can be used as a tool to manage weeds in container production.

What she’s found so far is that by sub-dressing fertilizers — strategically layering fertilizers at a certain depth underneath the soil — growers can successfully manage weeds in containers.

“Basically, the weeds cannot get to the fertilizer, whereas the ornamentals can and are able to compete well against any potential weeds,” Saha said.

This approach to withstanding weeds is both applicable for outdoor nursery and indoor greenhouse production. Using it in greenhouses has proven to be distinctly advantageous since there are strict limitations on the type and quantity of herbicides that can be used within the facilities before being considered harmful to ornamental plants.

In addition to the contemporary research it helps fund, Project GREEEN plays a role in the capacity to disseminate research to growers as well. Amy Start, executive director of the Michigan Christmas Tree Association, said funding has brought forth the opportunity for Bill Lindberg, an MSU Extension Christmas tree educator, to answer farmers’ questions and address their needs.

“I can’t say enough about how helpful that is,” Start said. “Educators not only do stuff like help at our meetings and put together information for growers, but they also travel to farms and do field visits.

“That kind of assistance is very rare, so we’re really happy Project GREEEN gives us the funding to keep that position going.”

Michigan State University AgBioResearch scientists discover dynamic solutions for food systems and the environment. More than 300 MSU faculty conduct leading-edge research on a variety of topics, from health and climate to agriculture and natural resources. Originally formed in 1888 as the Michigan Agricultural Experiment Station, MSU AgBioResearch oversees numerous on-campus research facilities, as well as 15 outlying centers throughout Michigan. To learn more, visit

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