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Ask the Expert: The Thick and Thin of Stem Density Management

May 7, 2021
Insights provided by two vegetation management experts reveal which solutions can be used to lower stem densities for good.

The height and density of incompatible stems directly impact the cost of vegetation management throughout utility right-of-way corridors. Leveraging industry best practices to reduce incompatible stem populations provides multiple benefits to vegetation managers. Conversely, when the proper control methods are not used, it can be difficult to achieve optimum results. We recently connected with Scott Wright, a vegetation management specialist with Corteva Agriscience, and Wes Graham, right-of-way manager and field biologist with Cooperative Energy, to discuss the challenges today’s practitioners commonly face. Their insights reveal the solutions that can be used to help vegetation management programs lower stem densities for good.

Why should vegetation managers focus on reducing stem densities as part of their vegetation management program?

Scott Wright (SW): Lowering stem densities of undesirable brush species will allow for early succession of desirable species, such as grasses and forbs. This provides multiple benefits, including wildlife and pollinator habitat support, soil stabilization, improved site accessibility and lengthened treatment cycles. As cycles are extended and fewer treatments are required in areas with lower incompatible stem densities, the most notable benefit for vegetation managers is a reduction in maintenance costs.       

What types of control methods would you recommend using to address areas where stem densities are a concern?

Wes Graham (WG): In certain scenarios, mechanical techniques should be considered to create an area that is conducive for herbicide applications. Treating tender shoots of undesirable vegetation with low-volume, directed herbicide applications increases the chance for successful control. If mowing is not an option, high-volume, foliar-applied spray can also be used successfully, but often at a higher cost per acre.

SW: Each situation can provide unique challenges, which is why Corteva continues to bring innovative solutions to vegetation managers, including new herbicide products and refined application techniques. I typically recommend low- and high-volume foliar applications as well as basal bark, cut stump and dormant-stem applications. Each application technique works in its own unique way to lower stem densities. It is very important to make the right choice for each situation.  

Why can it be difficult for vegetation management programs to lower stem densities and prevent future invasions of incompatible species?

WG: Two words: budgetary constraints. Money dictates the amount of acreage you can treat with herbicide applications, as well as the frequency of those treatments. Another reason is application contractor performance. One bad year can set a program back substantially. Everyone must buy into the goals outlined in the vegetation management plan to ensure success. Qualified, well-trained applicators play a pivotal role in achieving that success. 

What types of sites benefit most from stem density reductions?

SW: Higher stem densities most often appear on sites that do not utilize Integrated Vegetation Management (IVM) practices. This includes, but is not limited to, utility rights-of-way and roadsides. When mowing is used to manage incompatible stems on these sites every two to three years, higher stem densities and the germination of new brush species are common results. Instead of mowing exclusively, properly timed herbicide applications can be used as part of an IVM-based approach to enhance the results of mechanical brush removal and effectively lower stem densities throughout each application site.

WG: In a wetland, the topography dictates what species persist. A treatment area’s physical features will often impact the duration of plant species due to fluctuating water levels. Comparatively, upland areas converted to feature more desirable species of plants can be maintained more easily, allowing them to positively impact wildlife and support the development of pollinator habitat in a more cost-effective manner.

What factors can cause stem densities to increase?

SW: Only using mechanical means to control encroaching brush, or doing nothing at all, are key factors that cause stem densities to increase. By simply incorporating herbicide applications into a program, stem densities will reduce over time, which allows vegetation managers to achieve sustainable success.

Does application timing matter? Why/why not?

WG: Application timing is critical in achieving control of woody species. Initially, the size of the brush being controlled is a key variable that must be considered when designing and implementing a herbicide application program. Application should occur while plants are actively growing – preferably earlier in the growing season. As the dormant season draws closer, a plant’s rate of growth slows down and uptake of nutrients is greatly reduced, which leads to less herbicide uptake as a result.

Are there any products you’d recommend using in particular?

WG: Triclopyr is a great broad-spectrum herbicide that is grass-friendly.*

SW: No single product controls everything. Corteva provides a number of must-have products for undesirable brush control, but few are as versatile as TerraVue® herbicide. TerraVue was introduced to the market in 2020, providing a superb fit for foliar applications and total vegetation control (TVC). Many customers have already achieved noteworthy success through TerraVue applications. Otherwise, other herbicide products that Corteva customers commonly use include Garlon® 4 Ultra, Garlon® 3A, Transline®, Vista® XRT, Accord® XRT II and Opensight®.  Vastlan®, Freelexx® and Rodeo® are particularly effective in aquatic environments. 

*Vastlan and Garlon 4 Ultra are examples of products containing triclopyr. 

What about vegetation management programs with limited budgets? What can they do to control incompatible stems effectively?

SW: Limited budgets seem to be talked about now more than ever, and I always emphasize choosing an approach that delivers desirable, long-lasting results. Herbicides do just that while providing cost savings. By starting with the end result in mind, programs that use an IVM approach can effectively control incompatible stem populations and lower long-term maintenance costs in the process.

To learn more about lowering incompatible stem densities as well as the environmental and economic impact of using IVM-based strategies on the land you manage, click here.


Scott Wright
Scott Wright is a vegetation management specialist with Corteva Agriscience. Scott applies decades of agricultural experience to provide technical support, product recommendations and industry best practices to vegetation management customers throughout Texas and Oklahoma.

J. Wesley Graham
J. Wesley Graham is the rights-of-way manager and field biologist for Cooperative Energy, a generation and transmission utility that supports 11 distribution cooperative members throughout Mississippi. He is responsible for overseeing the vegetation management of over 1,800 miles of transmission line in 55 counties across the state.  Employing Integrated Vegetation Management (IVM) techniques, Wes and his group have developed habitat that promotes plant and wildlife diversity, while still maintaining reliability. In his 15 years with the utility, Wes has used his experience in habitat restoration and management to further Cooperative Energy’s goal of providing wholesale electricity in a safe, reliable and efficient manner.

™ ® Trademarks of Corteva Agriscience and its affiliated companies. Under normal field conditions, TerraVue® is nonvolatile. Milestone®, Opensight and TerraVue have 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 Opensight and to manure and urine from animals that have consumed treated forage. Consult the label for full details. Accord XRT II (glyphosate), Freelexx, Rodeo herbicide (glyphosate), TerraVue and Vastlan are 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. State restrictions on the sale and use of Garlon® 4 Ultra, Opensight, Transline and Vista XRT apply. Consult the label before purchase or use for full details. Always read and follow label directions. © 2021 Corteva. 

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