Winter Invasive Management

Taylor Wilson, Urban Conservation Technician

​Tired of Invasives? Winter is a great time to manage invasive plants or get a head start on spring management. Several invasive species are easier to identify in the winter and early spring because they’re evergreen or they produce leaves before native plants do. Often the green you see in a native landscape in early March is composed of invasive species. Many people take advantage of this by marking the easily identifiable plants, and then treating them when it's warmer and more comfortable to work. Below are several species that are easily identified during the winter months as well as species you can treat now. 

What can you ID?
If you aren’t confident with identifying invasive species, the below species are easy to identify in winter and early spring. They can be marked, often with spray paint or flagging tape, and then treated when it’s warmer.
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• Purple Wintercreeper: This plant is usually evergreen and very easy to identify. More info on identification. 
• English Ivy: Another evergreen plant that is easy to identify year-round. More info on identification. 
• Vinca major and Vinca minor: Commonly known as periwinkle, this is another evergreen vine that is easy to identify year-round. More info on identification.
• Bradford Pear: Occasionally pear trees will hold on to some of their fall foliage through the winter months. These are a distinct maroon red color. More importantly, pear trees are some of the first plants to produce leaves in the springtime. This makes them easy to identify against a mostly grey landscape. Pears also boom in spring, sporting several white flowers. Many people comment that the flowers have a distinctly fowl smell. More info on identification.
• Asian Bush Honeysuckle: Occasionally this plant will hold on to small red berries through the winter months. More importantly, bush honeysuckle is one of the first plants to produce leaves in the springtime. This makes them easy to identify against a mostly grey landscape. More info on identification.
• Garlic mustard: This is a biennial plant that produces evergreen basal leaves in the first year of its life cycle. These leaves grow close to the forest floor. This plant is easy to confuse with native violets and several other native species.  To make sure you have garlic mustard, you can grind a leaf between two fingers and should smell a distinct garlic scent. In spring, garlic mustard will shoot up into 2-3 foot tall stalks.  More info on identification. 

Pear stands in bloom courtesy of Daviess-Martin CISMA

Honeysuckle (green) invading a woodland. Photo courtesy: Don Miller

If you have any questions about identification, you can send clear photos of the leaves, bark, fruit, or buds to taylor.wilson@hamiltoncounty.in.gov​

What can you treat?

Manual Treatment
Manually treatment is any management that doesn’t use herbicide. Examples may be cutting, pulling, and mowing. Winter is a good time to manually treat invasive species that you can confidently identify.

• Purple wintercreeper, English ivy, and periwinkle (Vinca sp.) are best pulled manually when the ground isn’t frozen and is moist.
• Small pear trees and small bush honeysuckle can be manually pulled either by hand or with a puller bar. A puller bar is a tool that uses leverage and body weight to manually remove larger plants. You can borrow this tool from our tool loan program. 
• Garlic Mustard basal rosettes can be very easily pulled, but may be more difficult to find.  Make sure to get the root. At this stage, this plant can be confused with several native species. Read above to get a positive ID.

 
Chemical Treatment
Chemical treatment is any management that utilizes herbicides. The following invasives can be treated during winter months

• Japanese barberry and multiflora rose can both be cut surface treated.  This means you cut the plant so that about an inch of trunk is left. Then, herbicide is applied to the cut surface. Often a dye is used to make the herbicide visible. (see right)
• Japanese honeysuckle, periwinkle (Vinca sp.), English ivy, wintercreeper can be treated with a foliar spray when temp above 50 degrees Fahrenheit. 
• Tree of heaven can be treated with a basal bark treatment if there isn’t snow on the ground.

Honeysuckle in late fall in HOA woodland 

Cut stump treatment. Photo courtesy: Invasive.org

For more information on what can be chemically treated and what herbicide to use, check SICIM’s Management and Control Calendar. For more questions or information on treatment options, reach out to our office. 
 
With all this in mind, remember that the first step in the fight against invasives is preventing them from spreading. Hiking is a wonderful winter activity, just remember there are still invasive seeds on the ground. Use a boot brush or clean your hiking boots in other ways before moving between parks and other natural areas.  For more information, check out the PlayCleanGo article here. 

​Good luck managing!