Mechanical Controls: Weighing the Costs and Risks

Clear powerlines - Mechanical Control article

When grass by the roadside is four feet tall or trees are starting to encroach on a wire zone in a utility right-of-way, you need to get in, take care of the problem and move on; and often, that means mechanical mowing or trimming. But once the immediate issue is solved, what then? While it might seem easy to just go back to business as usual, a more thoughtful and proactive approach will help avoid problems like these in the first place, and reduce the frequency of other issues associated with mechanical vegetation control measures.

Mechanical Weed Control: Costs and Risks

Mechanical trimming and mowing obviously offers an immediate solution to overgrown grass or encroaching trees, and is a critical tool for any vegetation manager’s toolbox. That said, there are risks and downsides associated with mechanical control methods – risks that make it worth trying to avoid mowing whenever possible. Those risks include:

Fire. There’s no way around it – mowing increases the risk of fire. When a mower blade strikes a rock or piece of scrap metal, sparks fly – potentially igniting dry grass or brush.
Wildlife and habitat destruction. In addition to dramatically increasing the risk of fire, mowing is potentially hazardous to wildlife like ground-nesting birds. In addition, mowing destroys habitat critical to a variety of species, including pollinators.
Vegetation regrowth and spreading. Mow too early in the season, and you’ll just have to mow again later in the season; mow too late, and you’ll spread weed and grass seeds all along the mower’s path.
Reduced biological control. Beyond the destruction of bird, wildlife and pollinator habitat, mowing (especially in utility rights-of-way) reduces the level of biological brush control achieved when ground covers are allowed to flourish and ‘shade out’ undesirable trees and other vegetation.
Cost. Multiple studies conducted in both roadside and right-of-way environments have confirmed it. Mowing costs more – much more. From the equipment itself to the fuel, the labor, and the time, mowing is several times more costly on a per-acre or per-mile basis than selective herbicides and application methods.

IVM: A Better Way

So how can vegetation managers avoid the risks of mowing? By avoiding mowing, at least whenever possible. And that starts with a well-planned, well-executed integrated vegetation management program using selective herbicides as well as selective application methods. By choosing an IVM approach, vegetation managers can improve the overall effectiveness and cost-efficiency of their programs in these critical ways:

Less fuel for fire. Grasses and woody brush that don’t germinate don’t contribute fuel for potential wildfires. Plus, the equipment used to apply selective herbicides carries a dramatically reduced risk of spark and, therefore, of fire.
Improved habitat, with less danger to native species. Use of selective herbicides and application methods within an IVM framework actually preserves the native grasses and ground covers that serve as habitat for birds, pollinators and other species. In addition, less mowing means less risk to ground-nesting birds and other wildlife.
Reduced regrowth and spreading. If the weed seed never germinates in the first place, it obviously can’t regrow, and it can’t go to seed later in the year.
Improved biological control. Native ground covers that are allowed to flourish can quickly grow to crowd out invasive or undesirable vegetation species, reducing stem counts over the long term with no additional labor required.
Reduced cost. While the degree of cost reduction will vary depending on the application (roadside vs utility right-of-way, for example), study after study has demonstrated that an integrated approach to vegetation management significantly reduces VM costs over the long term.

Multiple studies like the State Game Lands 33 project in Pennsylvania have affirmed the environmental and economic benefits of integrated vegetation management, as well as the risks of relying solely on mechanical controls. If you’d like to learn more about how IVM can help protect the land you manage – and everything that lives in or on that land, visit VegetationMgmt.com.