MoDOT’s PGR program helps maintain several feet of clear zone along the roadside. In this zone, Plateau prevents fescue from forming seedheads and shifts the plant’s energy deep into the root, making a shorter, safer fescue more green and beautiful.

For nearly 13 years, roadside management specialist Rand Swanigan has worked to successfully manage the growth of fescue on Missouri roadsides. An introduced species, fescue is an important roadside and erosion management tool, but its fast growth can be expensive to control and makes it a potential safety hazard. In his role at the Missouri Department of Transportation (MoDOT), Swanigan traditionally prescribed mechanical methods, such as frequent mowing, to keep the tall grass in check. However, in recent years Swanigan and his MoDOT team have worked to put a customized Plant Growth Regulator (PGR) program in place. MoDOT’s PGR program has resulted in improved worker safety, reduced labor needs and more efficient use of the department’s budget. Thanks to Swanigan’s team, fescue is successfully managed along Missouri roadsides – including America’s Main Street, Route 66.

A perennial grass, fescue is used in Missouri and other southern states where it thrives not only due to the region’s hot, humid temperatures, but also because of the plant’s adaptability to harsh growing conditions. Fescue is resistant to drought, can survive short flooding periods and is even capable of surviving in acidic soils, such as sandstone and shale. The grass is a cool-season species and produces its most vigorous growth in the spring and fall. MoDOT works to maintain fescue and native vegetation along the state’s roadways where it serves as both a beautification tool and an aid to erosion control. Vegetation like fescue helps control erosion from road surface runoff.

Despite the plant’s beneficial qualities, fescue, which is typically planted within 30 feet of the road surface, must be kept under control in roadside areas. Growing 36 inches tall or higher in an average season, fescue can quickly grow to disrupt natural habitat and obstruct sightlines for drivers. Without frequent mowing or the benefit of seedhead suppression through a PGR program, the plant can quickly create sight distance concerns.

However, with nearly 32,000 miles of state highways to maintain, MoDOT requires an economical method of maintaining roadside vegetation such as fescue. Traditionally, Missouri’s 10 roadside management districts relied on mowing to control the roadside growth of fescue. But, the costs for MoDOT’s mowing program were considerable – averaging around $40 to $45 per acre mowed. With nearly 250,000 acres to mow an average of three to four times a year, the department’s fescue-mowing costs were growing nearly as fast as the fescue.

About 15 years ago, MoDOT began exploring the use of a PGR program to reduce the need for mowing, cut labor costs and improve worker safety. “When we started our PGR program in Missouri, we were trying to find a way to mow less, but still get the same results,” Swanigan said. “Herbicides are an important tool to help accomplish this goal.”

The cornerstone of a PGR program is the use of a herbicide that suppresses seedhead formation, but allows fescue to thrive while keeping the plants at a safe, manageable height. In addition to a herbicide that regulates growth, PGR programs typically include a herbicide for control of broadleaf weeds, depending on roadside conditions.

Black-eyed Susan and other desirable wildflowers freely flourish on PGR-treated roadsides throughout Missouri.

In developing an effective PGR program, MoDOT tested a number of herbicides in an effort to successfully suppress seedheads, but each had drawbacks.

“The first PGR herbicides we tested only gave us a three week window for application,” said Swanigan. “With 32,000 miles to take care of, this created a serious time limitation.”

After struggling with other herbicide products, MoDOT began looking into the benefits of Plateau® herbicide, containing the active ingredient imazapic. Swanigan, whose interest was driven by the product’s successful use in converting areas to native grasses, tested it for two years to ensure the effectiveness of the product.

Working with his BASF sales representative, Randy Lusher, and MoDOT’s roadside managers, Swanigan conducted test plots throughout Missouri’s 10 roadside districts.

“We tested imazapic in ‘real world’ plots that spanned up to a mile along busy roads,” said Swanigan. “This gave us the ability to compare the PGR area with other roadside management techniques in a given district.”

The MoDOT’s test plots were very successful where it counts – in reduced work hours dedicated to vegetation management. In some cases, areas that once required a minimum of three mowings or more to control fescue required only one mowing under the PGR program.

“The PGR tests demonstrated that we could stretch out our mowing cycles and put the labor force on the road surface, which is our priority,” said Swanigan.

According to Dan Sherbo, the Roadside Manager for MoDOT’s South Central District Nine, these results drove the adoption of a PGR program in his district. In 2003, District Nine used the imazapic PGR program to treat over 6,000 acres of roadside – which is about a quarter of the total PGR acres the MoDOT managed that year.

“The PGR program reduced our total number of mowings and made the mowings we did do easier because the grass was at a more manageable height. Also, it’s faster and safer to apply herbicide than it is to mow,” said Sherbo. “This total reduction in labor hours dedicated to vegetation management, along with reduced equipment and material costs related to the PGR program, reduced our roadside costs by $300,000 from 2002 to 2003.”

Sherbo’s district has the added responsibility of taking care of a portion of Route 66, one of the most famous highways in America. As a result, Sherbo and his team made sure the PGR program not only saved money, but also improved the image of the roadside.

Top: A PGR program, like the one developed by Swanigan, helps maintain erosion control, visibility and driver safety on America’s favorite highway. Inset: Mo DOT spray trucks use state-of-the-art rotating sprayers for increased safety and targeted application. The special tank and sprayer design allows herbicides to be mixed as needed during application and helps prevent drift to non-treated areas.

“With imazapic – our PGR herbicide – the plant’s energy doesn’t go to the seedhead, it goes to the root system. So, grasses look green even during the dry season, which is a significant beautification benefit.”

Swanigan has successfully introduced the PGR program to his statewide team of applicators and roadside vegetation managers. In 2003, MoDOT had 25,000 acres under PGR, which reduced the mowings on Missouri’s PGR-treated roadsides from a typical three or four times a year to only one or two cycles per year. With the reduction in mowings and transfer of labor to other priorities, MoDOT has enjoyed nearly $3 million in cost savings. The use of the herbicide has also helped decrease equipment and maintenance costs, delay the need to buy new mowing equipment and improve safety conditions for employees, who are not required to mow as regularly in perilous roadside areas.

“This is a much better alternative to having personnel out on the roads mowing,” Swanigan said. “A lot of our roads are two-lane highways with narrow or no shoulders, so it’s safer for our workers if they don’t have to be out there mowing in traffic.”

The use of imazapic on Missouri’s roadsides controls fescue without harming other desirable vegetation. Plateau is a Smart Herbicide™, meaning it affects an enzyme found only in the targeted vegetation and not humans, animals or insects.

“Other native plants, like purple coneflowers, black eyed susans, coreopsis and Missouri evening primrose thrive along our roadsides,” Swanigan said. “Imazapic doesn’t affect those plants, so the beautification portion of our PGR is successful.”

The environmental impact is especially important in Sherbo’s District Nine, which includes the Mark Twain National Forest. To implement the PGR program, the vegetation management team worked closely with the National Forest Service to make sure the herbicide was appropriate for use in this important habitat.

Swanigan says he and his team plan to continue leading their 10 districts in Missouri using the PGR vegetation management program. If you’re passing through Missouri, check out how the PGR program helps keep Highway 66 — “the highway that’s the best” — and many others just that way.

For more information, contact Andrea Cuff, Padilla Speer Beardsley, 1101 West River Parkway, Suite 400, Minneapolis, MN 55415, (612) 455-1705 or acuff@psbpr.com.