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Saving Treatment Season With Dormant-season Applications

Oct. 5, 2023
Invasive brush species can grow up to 40% in one year, meaning that once you fall behind on treatments, you increase both the likelihood and severity of the potential impact to infrastructure. Learn how to make your dormant-season treatment a success.

It’s late summer. Labor shortages, erratic weather patterns, wildfires or budgetary constraints have put you behind on vegetation treatments; you can practically hear the brush growing out of control. Can the treatment season be saved? Can you still protect critical infrastructure and access without resorting to less desirable nonselective vegetation control measures? Absolutely. But it’ll take the right approach, implemented at the right time and in the right manner.

Getting Behind: What’s the Harm?

Invasive brush species can grow up to 40% in one year, meaning that once you fall behind on treatments, you increase both the likelihood and severity of the potential impact to infrastructure. Plus, research has shown that missing a treatment season means you’ll have to spend more effort, more time and more money to effectively control vegetation on a given acreage the next season.

And while the temptation may be high to resort to nonselective mechanical control measures like mowing, that approach comes with a price as well. Mowing leaves the plant’s root system intact, allowing it to resprout and spread. And when you consider the environmental impacts of mowing, the fluctuating cost of fuel, and the resources required to maintain and operate a fleet of equipment, it becomes clear that mowing isn’t a sustainable long-term strategy.

So how can you get ahead of the VM curve? Dormant-season treatments may be the answer.

The Dormant-season Advantage

Typically made from late winter through early spring (after fall leaf senescence and prior to roughly 25% greening in the spring), dormant-season applications help extend the vegetation management window and can help you catch up on this year’s treatment or get ahead of the next.

But dormant-season applications offer benefits beyond just vegetation control. Since treated brush doesn’t green up in the spring, you can avoid widespread “brownout” effects and minimize the risk of complaints from the public. By using selective chemistry and application methods, you preserve beneficial vegetation and help ensure a lush spring greenup. And because dormant-season applications are made during the off-season, managers can keep their employees busy year-round — all while getting the most from end-of-year budget dollars.

Ensuring Success

As with nearly any vegetation management strategy, the success of your dormant-season treatment depends on making the right kind of application — dormant-stem, basal bark or basal cut — and using the most appropriate products.

For brush up to 10 feet tall or 2 inches in diameter, dormant-stem treatments can be made anytime from leaf senescence in the fall through 25% leafout in the spring, and usually involve applications to the trunk and stems of invasive species. Basal oils can help optimize uptake for maximum efficacy. A tank mix featuring Garlon® 4 Ultra herbicide and TerraVue® herbicide from Corteva Agriscience works well for dormant-stem treatments.

Basal bark treatments use a highly targeted application method combined with a selective herbicide or tank mix. Targeted stems no larger than 6 inches in diameter are treated on the lower 12-15 inches of the stem; the mix translocates to the roots and other stems, preventing regrowth. Appropriate products for basal bark treatment include Garlon 4 Ultra herbicide.

Basal cut-stump treatments are made to woody plants that have been individually cut; application is made to the cambium layer and any remaining bark or roots. Products such as Garlon 4 Ultra herbicide are effective against a wide range of species and work well when used for basal cut-stump treatments.

Regardless of the type of treatment, you can go a long way toward ensuring success before you even make the first application. Have a plan before you need it so you, your crews and your vendors are ready should the need arise. Get input from your chemical supplier or licensed applicator on recommended rates, adjuvants, tank-mix partners and application methods. And be flexible – dormant-season applications allow for variability in timing, so don’t feel like you have to rush.

To learn more about best practices and products for vegetation management in utility rights-of-way, visit, or see the complete portfolio of industry-leading content available at

™ ® Trademarks of Corteva Agriscience and its affiliated companies. Under normal field conditions, TerraVue® is nonvolatile. TerraVue has no grazing or haying restrictions for any class of livestock, including lactating dairy cows, horses (including lactating mares) and meat animals prior to slaughter. Label precautions apply to forage treated with TerraVue and to manure and urine from animals that have consumed treated forage. TerraVue is not registered for sale or use in all states. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your state. Consult the label for full details. State restrictions on the sale and use of Garlon® 4 Ultra apply. Consult the label before purchase or use for full details. Always read and follow label directions. © 2023 Corteva.

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