by Travis Hirst, Dow AgroSciences
Herbicides play a vital role in operations for the Duck River Electric Membership Corp. (DREMC) in south central Tennessee. With five operating districts serving more than 70,000 members and responsibility for 6,000 miles of electrical distribution line, DREMC began a robust herbicide vegetation management program with its first trial in 1999 as part of a larger line-clearance initiative.
DREMC rights-of-way supervisor Jim Barnhart has been instrumental in setting the objectives of the program and seeing it implemented.
“The program was planned with several objectives in mind, including managing problem vegetation within our ROWs (rights-of-way), improving electric reliability and increasing accessibility for our service personnel,” Barnhart said. “We also are working to accomplish these objectives while promoting environmental stewardship and cost-effectiveness, which requires us to balance environmental concerns, public needs and safety by utilizing industry best management practices.”
DREMC staff developed its program with these best practices in mind. A member-notification plan, stringent contractor requirements and preapproved herbicide mixes were established to help ensure its success. And with herbicide applications’ being the cornerstone of the program, DREMC established another goal at the onset of work: reducing undesirable vegetation and the amount of herbicide active ingredient applied.
Barnhart said DREMC proactively educates staff and alerts its members of upcoming herbicide treatments in their areas, which is integral to the plan.
“Our typical spray season starts on or around June 1, and to help ensure a trouble-free season, we start the process with a formal training meeting in March that details the program with both the herbicide applicators and DREMC’s spray coordinators,” Barnhart said.
Each April, an article touting herbicides runs in the cooperative member publication, the Tennessee Magazine, including DREMC’s contract applicator information and how members will be notified if they are on a circuit scheduled for treatment. Then, in May’s membership billing, an herbicide-application notification is included with the monthly billing to those members.
Front-end member notification limits potential issues down the road. After notification, Barnhart said, for every member who requests no spraying be done on his or her property, another inquires about the herbicides and how he or she can get some for personal use.
In June, all applicators along with their respective DREMC spray coordinators attend a start-up meeting with an on-site review in their designated districts.
“The DREMC spray coordinators are key to a smooth and efficient application season,” Barnhart said. “They know critical access points and areas where no brush exists and use that knowledge to improve the efficiency of the crews. They also provide on-site assistance if there is a misunderstanding with a property owner.”
The program is scheduled to operate on a four-year cycle with 1,000 to 1,600 miles of line treated per season. It authorizes contractors to perform herbicide applications under the direction of DREMC’s staff forester.
DREMC has a four-year contract with Southeast Woodland Services to complete the work. DREMC compiled a comprehensive list of requirements with the intent to proactively curb potential issues. Some contractor requirements include:
à¢— All trucks used must have their contractors’ logos and names clearly displayed on the sides along with furnished magnetic signs that read “Duck River Herbicide Contractor.”
à¢— DREMC will assign a spray coordinator to work with crews in each district and will assist the crews in finding spray locations and with member relations and notification.
à¢— Re-treatment is performed at the cost of contractors.
à¢— Contractors must guarantee 95 percent control on a treated span-by-span basis.
à¢— Contractors must be state-licensed and certified.
Application Methods, Herbicides
Three herbicide application methods were approved for use by DREMC at the project onset. A low-volume backpack foliar spray is used for most applications. The program also approved two additional methods for use when low-volume backpack spraying isn’t feasible, such as when brush is too tall for foliar treatments or where the risk of off-target damage is considered too high. In these cases, basal or hack-and-squirt treatments are used.
Contractors also must use only approved herbicides as defined in the program. For low-volume foliar treatments, the approved combination is 3.1 percent Accord Concentrate specialty herbicide mixed with 0.3 percent Milestone VM specialty herbicide, 0.5 percent Arsenal Powerline, with a blue dye and 100 gallons of water. For basal applications, the mix is 20 percent Garlon 4 Ultra specialty herbicide with 1 percent Stalker combined with a blue dye and basal oil. For hack-and-squirt applications, the mix is 20 percent Accord Concentrate with 6 percent Milestone VM and 8 percent Arsenal Powerline with a blue dye. All herbicides are provided as custom blends, in a closed system micromatic drum valve, returnable and refillable container system that provides closed chain of custody. Some of the more prevalent problem vegetation in the DREMC rights-of-way includes hackberry, box elder and cedar.
“The application methods and herbicide mixtures required by the program are designed to allow selective treatment of target species while promoting a biodiverse plant community that is compatible with overhead electric power lines,” Barnhart said.
As the second application cycle progresses, brush size and density have been reduced noticeably, and an increase has been observed in native grasses, herbs and forbs.
“As a result, we’ve seen turkey, deer and birds all frequenting the ROW areas,” Barnhart said. “In addition, accessibility has been greatly improved, which has improved restoration times and decreases the tree crew’s workload.”
Another goal met was reducing the total volume of herbicide applied. In 2009, Barnhart and his associates collected application data and examined it against 2005 data. Since the start of the program, a large portion of the system has been completed that can be compared directly with the 2005 season, with the comparison measure being gallons of mix applied per line mile. In 2005, application rates averaged 17.79 gallons per mile, and in 2009 that number fell to 9.11 gallons per mile.
As the program cycle winds down, Barnhart also has learned that some of the key elements in a successful program are selecting qualified application contractors, building long-term relationships and striving for continuous improvement.
Doing so has resulted in its initial four-year contract’s achieving a 28 percent cost savings to date.
“Just as the plant community is never static, the roles of the managing forester, applicator and herbicide manufacturer can never be static,” Barnhart said.
Travis Hirst is the product manager of U.S. integrated vegetation management at Dow AgroSciences. Reach him at email@example.com or 317-337-7280.