You Can Identify and Manage Invasive Species this Winter!

Taylor Wilson - Urban Conservation Technician

​Tired of Invasives?
Winter is a great time to manage invasive plants and get a head start on spring management. Several invasive species can actually be easier to identify in the winter and early spring than in the summer. This can be because they’re evergreen, they have a distinct winter color, or they produce leaves before native plants do. Many people take advantage of this by working on invasive management during the winter, or by marking the easily identifiable plants, and then treating them when it's warmer. 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. Or if you don’t mind the cold, see “What can you treat?” below.

• 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 its fall foliage through the winter months. The leaves are a distinct maroon red color. More importantly, pear trees are some of the first trees 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 distinct foul smell. More info on identification.
• Asian Bush Honeysuckle: Sometimes this shrub will have small red berries through the winter months, and it has a somewhat distinct striped bark. More importantly, Asian bush honeysuckle is one of the first plants to produce leaves in the springtime. This makes it 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 ground and stay green-ish through the winter. The leaf shape of the basal leaves can be easy to confuse with native violets and some other native species. To positively identify garlic mustard, you can grind a leaf between your fingers and it should have a distinct garlic/onion scent. In spring, garlic mustard will shoot up into 2-3 foot tall stalks. More info on identification. ​

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

​Manual Treatment
Manual treatment is any management that doesn’t use herbicide. Examples may be cutting, pulling, and mowing. 

• Purple wintercreeper, English ivy, and periwinkle (Vinca sp.) can be pulled manually when the ground isn’t frozen and is moist. If there is a large area of vines, you might consider chemical control to reduce the risk of erosion and related damage . 
• 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 plants that can’t be removed by hand. You can borrow this tool from our tool loan program. 
• Garlic Mustard basal rosettes can very easily be pulled by hand. 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 invasive species can be treated during winter months

• Woody vegetation (multiflora rose, Asian bush honeysuckle, callery pear, or anything with a woody stem) can be cut surface treated. This is done by cutting 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. 
• Japanese honeysuckle, Vinca species, English ivy, and wintercreeper can be treated with a foliar spray when the temperature is above 50 degrees Fahrenheit. 
• Tree of heaven can be treated with a basal bark treatment if there isn’t snow on the ground. Basal bark treatment is recommended for this species instead of cut surface treatment due to tree of heaven's strong resprouting response. 

For more information on what herbicide to use for each species, check SICIM’s Management and Control Calendar. For more questions or information on management options, reach out to our office. 
 
With all this in mind, remember that the first step in the fight against invasive species is preventing them from spreading. Hiking is a wonderful winter activity but 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.

Good luck managing!