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Identification of Invasive Species During the Winter

MAKANDA, Ill.- Even during the dormant winter season, invasive plants species are major threats to the forests and grasslands of southern Illinois. They can outcompete native species, decrease wildlife habitat, increase management costs and limit tree growth and regeneration.

Many species may be easy to identify during the growing season when their leaves and flowers are visible but this task is more complex during winter dormancy. During a recent workshop held at Giant City Visitor’s Center, Extension Forester Chris Evans discussed what characteristics to look for during winter identification of invasive plants.

Evans noted that some species are unique and easy to spot even during the winter due to their bark color or texture. During the workshop, individuals could get an up-close look at invasive species in their winter state as Evans passed around examples such as autumn olive (also locally called Russian olive), Callery pear, honeysuckle, privet, tree of heaven and wintercreeper.

One particular example discussed was burning bush. Over the past decade, this invasive has quickly spread and is now well established within various regions of southern Illinois. Heavily populated pockets can drop seeds and spread quickly. This invasive species is so prominent in the northeast that it is no longer sold in many states.

Invasive species can move into an area and create their own ecosystem where they can grow faster and spread quickly. Many invasive grow so vigorously, they can displace native plants and cause damage to the ecosystem. “It is scary to watch how land can change once invasive species gain a foot hold. Sometimes it is hard to even recognize a place afterwards,” said Evans.

Evans stated that “invasive plants used in landscaping are often a source of new infestations. Their seeds can spread long distances sometimes with the help of birds and other animals.” While it’s not necessary to immediately remove, it is a good idea to move away from these species as you begin to change landscape.

Woody plant control performed this time of year includes cutting back the plant and painting the stump with herbicide. Check the label as some herbicides are not appropriate for a winter application. Those that require mixing with water can freeze during the cold months.

Evans warned that many invasive plants look very similar to other native plants. “Be sure to identify a few different characteristics to ensure you don’t mistakenly control a desirable native,” said Evans. A few resources that you can use are the Seek app through iNaturalist or the PlantNet Plant Identification app.  

Nick Seaton, project coordinator for River to River Cooperative Weed Management Area, was also on hand to discuss a program in partnership with the Southern Illinois Prescribed Burn Association (SIPBA) and Forest Restoration Support Team (FRST) that assists landowners with the invasive species management. The program provides herbicide, equipment and training necessary to empower landowners to remove invasive plants. In order to participate, individuals must document hours showing how much time was spent on invasive species management.

At the conclusion of the program, participants ventured outside to identify natives and nonnative species near the visitor’s center.  For more information on invasive species management, contact Chris Evans at (618) 695-4917. Those wanting more information about the invasive species program can contact Nick Seaton.

News Source: Chris Evans, 618-695-4917,

News Writer: Heather Willis (618) 357-2126,