by Travis Waters, Dow AgroSciences Vegetation Management
Unwanted trees can challenge vegetation managers tasked with providing reliable power to customers by keeping power lines and rights of way clear of vegetation.
Options for maintaining encroaching trees include cutting trees, mechanically side trimming the trees or using herbicide to control either entire trees or part of their growth, called chemical side trimming.
Mechanical cutting can be dangerous, time-consuming and expensive. Herbicide is a good alternative in many situations. Using herbicide to chemically side trim a tree allows vegetation managers to control the part of the tree that presents hazards to nearby power lines while keeping the desirable part of the tree alive and healthy. When used correctly, certain herbicides can prune back the treated limbs without controlling the entire tree.
Side Trimming Utility Rights of Way
Helena Chemical Co. based in Collierville, Tenn., a distributor and applier of herbicides in the vegetation management market, has used chemical side trimming to maintain clear and accessible utility rights of way.
The company focuses efforts on two types of chemical side trim applications: foliar treatments and dormant stem treatments, said Geer DuBose, vegetation management branch manager with Helena.
“We’ve seen great success with both treatments,” DuBose said. “Our foliar treatment consists of Milestone specialty herbicide at 7 to 10 ounces combined with Krenite herbicide at 2 to 4 percent in 100 gallons of water plus a drift control agent. Our dormant stem treatments use one of two mixes. One is a combination of Milestone and Garlon 4 Ultra specialty herbicide, and the other combines Milestone and Trycera herbicide. Both of these mixes include a high-quality 3 percent v/v oil to ensure good penetration.”
Georgia Electric Membership Corp. is one Helena customer that has seen impressive results from chemical side trimming.
“There have been fabulous results so far,” DuBose said. “The treatments are holding back the vegetation very well. We are seeing maintenance cycles extended by three to four years over mechanical treatments, and the treatments were initially less expensive, as well.”
For many utilities, it’s difficult to move away from traditional mechanical treatments. DuBose cites two main reasons: worries about customer reaction to vegetation brownout and perceived costs associated with chemical side trimming.
“One challenge associated with chemical side trimming is the visible brownout,” DuBose said. “But if you are willing to accept that it’s going to happen, as well as be proactive in explaining the benefits of this type of application to customers or the public, you can mitigate most issues. At the same time, you have to be extra careful in residential areas, and in some cases, use mechanical treatments when treating areas like subdivision entrances.”
To address perceived costs and to demonstrate the cost-effectiveness of chemical side trimming over purely mechanical treatments, Helena has developed a cost calculator.
“When you walk into a utility and tell them that chemical side trimming will cost 20 percent less than their current mechanical treatments, the first reaction I normally get is, “˜That’s not a high enough number to make me switch,'” DuBose said. “But when I crunch the numbers using our calculator and then show all the cost benefits, including the saving associated with extending their treatment cycles, that gets their attention.”
Chemical side trimming provides longer-lasting results than mechanical trimming alone.
Adding extra dimensions to its side-trimming capabilities, Helena has developed a patent-pending delivery system to help its applicators treat tall vegetation with better accuracy and less chance of off-target damage as a result of spray drift. The delivery system can be mounted to various vehicles and includes a telescopic arm that can extend 40 to 60 feet in the air and is outfitted with spray nozzles. The nozzles are interchangeable from fan to cone, depending on the application.
“Our system allows us to apply side trim treatments on very tall vegetation with precision and accuracy with less spray drift and less waste in terms of herbicide solution,” DuBose said. “The generally accepted method of treating branches that high was to simply shoot the spray up there from the ground. But that method can require applicators to use much more herbicide solution in terms of volume sprayed, create opportunity for spray drift and expose applicators to falling spray solution.”
Travis Rogers is the market development specialist for Dow AgroSciences Vegetation Management business. Prior to his current role, he served as a vegetation management specialist with Dow AgroSciences, covering a territory in the southeastern U.S.