A New Approach to Woody Invasive Species Control: Leveraging Native Warm-Season Grass Cover Crops

November 1, 2024

As we head into the fall and winter season, tackling invasive brush in the Midwest remains top of mind. Our goal is to find effective, efficient, and environmentally sustainable solutions to control invasives, and our latest approach leverages native grasses for a natural and cost-effective solution.

Moving Beyond Traditional Brush Control

The traditional method of controlling invasive brush often involves heavy reliance on herbicides and expensive equipment and human efforts. So when you make that investment you want it to be a durable long lasting solution. While herbicides can be effective, if we can use less of them, our environment will be better off for it.

Reducing our dependence on herbicides not only saves costs but also protects native ecosystems. Enter native warm-season grass cover crops as a nature-driven alternative that allows for sustainable brush control while minimizing the need for chemicals.

The Role of Native Grasses in Brush Management

Historically, invasive brush like Bradford pear, autumn olive, multiflora rose has outcompeted native grasses in our prairies, wet prairies and even open woodlands, leaving us with insufficient fuel for prescribed fire in those smothered areas. This fire, a powerful tool in our arsenal to rebalance the herbaceous/woody balance. Fire helps to control woody species and maintain a healthy ecosystem. By quickly establishing a native grass cover, we can restore this natural balance and reduce our dependence on herbicides.

Choosing the Right Native Grasses for Restoration

After experimenting with various native grasses, we've identified many cover crops that are ideal for natural areas restoration. There are even several native cover crops that perform well in many environments like Canada Wild Rye (Elymus canadensis) and Virginia Wild Rye (Elymus virginicus). These are great at covering the ground quickly especially when trying to control herbaceous weeds in mesic and wet prairie and establishing grasses in oak woodlands.

However, these native plants are cool season grasses so when it comes to using them to establish fuel for controlled burning they can be limiting. These native grasses are usually still green during the fall burn season and sometimes late in the spring season so their burning effectiveness can be stunted. Cool season grasses have their advantages, such as two optimal establishment periods in spring and fall, however in the context of this conversation establishing fuel is top priority.

The traditional challenge with warm-season grasses is their slow establishment, often taking 3-5 years to mature. That is where Side-Oats Grama (Bouteloua curtipendula), a warm season grass has emerged as a top contender when working on invasive brush in prairies, and wet prairies, even open woodlands. Side-Oats Grama bucks the 3-5 year timeline of most warm season grasses, germinating quickly and providing ground cover in its first year. This rapid and dense establishment is crucial for quickly restoring fire-supportive fuel loads and suppressing invasive species.

This hardy, versatile grass germinates rapidly, spreads quickly, and can even produce seed in its first year. It's like having a team of tiny, hardworking gardeners establishing a fuel source and suppressing weeds at the same time. On top of that, Side-Oats seed is cheap!

One other added benefit we have noticed with our experimenting is that Side-Oats serve as a great cover crop in burn scar areas, quickly healing that area over and reducing herbaceous weed invasion.

Remember this is a cover cope intended to cover the ground for a short period to time to solely achieve the goal of establishing fuel and temporary native cover. If you care to add diversity or add in longer lived warm season grasses back into the site once you have established the fuel , you can always do that, side oats is very accommodating to over seeding.

Brush Management Process Using Side-Oats Grama

Control the Brush: Use your preferred method, whether it's cutting, forestry mowing, feller buncher, and/or herbicide application. If using herbicide use the least caustic choice and ensure it does not have a long residual that could inhibit seed germination.
Seed the Area: Immediately after control, broadcast Side-Oats Grama seed, Elymus (native rye) and bluestem species, over the cleared area. Typically the best time to seed is between November - May. Since this species does not require cold moist stratification, we preferer to hold seeding until just before its germination period to avoid it becoming expensive food for the birds. This then would be optimal in April or May in many Midwest states. Seeding rate will vary depending on your desired outcomes and the sites needs. If you would like help determining a strategy please see details about consultation at the end of the article.
Establish the Stand: Often times not much is needed to establish a thick stand of side oats. If annual weeds become an issue you can mow several times per year to keep them at bay (both height reduction and seed set prevention of weeds) to aid in establishment. In the first year you should be able to determine if your seeding was successful as they are quite apparent to the trained eye, just months after seeding. If seeding was not successful, determine the reason, mitigate the reason, and reseed the next opportunity. Usually by the end of the second year you should have a dense enough stand to conduct an effective fire on your woody invasive resprouts.
Monitor and Manage: Regularly inspect the site and conduct burns to control invasive growth as needed to maintain the health of the grassland and control any new invasive growth. If necessary, a second application of broad leaf herbicide could be used to aid in control. Since broadleaf selective herbicide only kills broadleaf plants, and leaves grasses and sedges largely unharmed, your side oats will be largely intact after a treatment, although superficial damage may be noticed, please use your herbicide label to inform your choice. After your second treatment, again consider an over seeding to better solidify your efforts.

Benefits of Native Grass Cover Crops

This approach not only limits herbicide use but also promotes biodiversity, enhances soil health, and builds resilience into your landscape. Our natural solution offers long-lasting control that balances the ecosystem while efficiently managing invasive species.

We can provide more in-depth and customized plans for your natural area, and we can even accomplish this many times for free. Email us john@naturalcommunityservices.com