Simple strategies for managing woody encroachment

By Gilbert Randolph, QF Regional Communications Specialist

Springtime is here, which means trees are leafing out, green is coming back to the landscape, and many landowners are excited to start more habitat work. Stopping woody encroachment from invasive species and aggressive native species requires thoughtful planning and consistency. Here are a few things landowners can do to control these woody pests this spring.

"Spring is a great time to get a head start on managing woody encroachment," said Valarie Kurrie, a Pheasants Forever and Quail Forever coordinating invasive species biologist.

Even if the plants aren't removed immediately, they can be flagged with orange tape so that they can easily be found and removed later in the season. Learning to identify common invasive species will help make sure these problem plants can be managed before they get well-established.

For those landowners who want to get started on removal, most of these problem species require herbicide to effectively control. They are notorious for being able to re-sprout from cut stumps and some can even spread via horizontal roots to put out new shoots. Triclopyr, known under brand names such as Garlon, is an effective option for most invasive species. While there are some species, such as bush honeysuckle, which can be resistant to triclopyr when they are larger, this herbicide works on most woody plants. For large bush honeysuckle plants, glyphosate may be a more effective option.

For small plants, foliar spraying is a good option. Foliar spraying is simply applying herbicide to the leaves of a plant, making sure to cover all the leaves with herbicide. When native plants are dormant, the leaves of smaller invasive plants can be sprayed. This strategy is a great way to control the new sprouts which come up from the seed bank after larger plants have been removed. Additionally, larger plants can be brush hogged and then foliar sprayed when new shoots appear from the base. While larger plants can be controlled this way, it is not recommended to spray plants above your shoulder line, as it can lead to more herbicide drift and potentially to unsafe chemical exposure.

Larger woody plants can be controlled using two main methods; cut stump and basal bark application. Cut stump treating involves cutting down the stems of larger woody plants and then treating the cut area with herbicide. This is often done with glyphosate. For larger plants that are resistant to triclopyr this is the method of choice. The downside to cut stump treatment is that it requires carrying two different tools and switching between them. Stumps must be treated within about thirty minutes for the herbicide to be effective, so this management technique is best done with help.

The other method, basal bark application, involves mixing herbicide with specially designed oils and then applying it to the base of the plant. This method is only effective for thinner barked species such as autumn olive, honeysuckle and maples. The main advantage here is the ability to carry one tool and not have to immediately cut the main stem of the plant. Basal bark applications can save you time as well as save your back. The specific ratio of triclopyr to basal bark oil can be found here. Often it is recommended to use 20-30% triclopyr and 70-80% basal oil, though some premixed options like Pathfinder II have a lower concentration. Make sure to check the label to see if the chemical product is compatible with basal oils and if using near bodies of water, use an aquatic approved formula and don't apply herbicide before rain events.

The gear you'll need includes the following: a backpack sprayer, preferably with a nozzle shut off valve to keep it from dripping, rubber boots, chemical resistant gloves, eye protection, and clothing that covers all exposed areas of the body. While triclopyr is considered a low toxicity chemical for humans, it's always best to make sure you don't get herbicide on your skin, in your eyes or breath it in. There are a variety of backpack sprayers available on the market. Harbor freight's 4-gallon backpack sprayer is an entry level option that is around $40-60 depending on sales. Higher end sprayers are available as well, and range in price from $100-400+ depending on the make and features.

It's also important to not let herbicide sit in the sprayer for extended periods of time. Basal oil mixes can damage the seals on sprayers and cause them to leak and need repair. It's best to mix just what you think you'll need and have a sealed, labeled container for storing excess herbicide.

Whether using a simple foliar spray, cut stump or basal bark application, spring is a great time to get started pushing back woody encroachment and invasive species. To learn more about what herbicides and application methods are best for your situation, contact a Pheasants Forever biologist.

Thanks to our partners at Working Lands for Wildlife — learn more about tackling woody encroachment in the Great Plains or the Sagebrush Biome.