Vegetation Management: More Is Less
As gasoline prices rise, more states are using grasses and forbs that require less maintenance.
Many states were already struggling with tighter operating budgets when world crude-oil prices, as well as 2005's crippling hurricane season, caused double-digit gasoline cost increases. Not only does mowing and trimming equipment run on gasoline, but so do the vehicles that transport maintenance equipment and the workers who operate it. Therefore, in addition to using plants that help control erosion, state departments of transportation needed to find species that required less maintenance and mowing.The Difference Three Years Makes
When last interviewed for Erosion Control in 2003, Clyde Mason, landscape supervisor with Indiana's Greenfield District (from Indianapolis to the north central area of the state), reported that his rights of way usually used Kentucky 331 fescue, which grew to 15 inches before it was cut down to 5 inches. The district's 100-foot-wide rights of way were mowed in May before Memorial Day, every site received a full-width mow in June, and a 15-foot roadside strip was mowed in urban areas during August. Mason also mentioned that his crews didn't mow where forbs, flowers, and native grasses were taking hold—many of which his crews were actively planting.
"Our roadsides contain mostly warm-season grasses that don't have to be mowed often—prairie dropseed, bluestems, some forbs," Mason now says. "The public believes that's better than regular grasses. These native-type grasses are nearly 'no maintenance.' The public won't complain much if these grasses are high."
As if unpredictable gasoline prices weren't enough to tax one's budget, Mason's road crews have to share their resources with snow-removal crews. "We operate under a big, broad budget. We don't have an operating budget per se, but we're under a big budget for all roadside maintenance. If we have a snowy winter and road crews must use a great deal of salt, when spring comes around, we won't have much money left over for our work. Mowing isn't mandatory, but we have to do 'ice patrol' on our roadways."
According to Mason, the Federal Highway Administration requires a certain percentage of states' roads to be seeded with native plants. Whereas little bluestem grass grows to about 2 feet high, big bluestem and Indian grass can get as tall as 6 feet, which may offer Indiana an added benefit. "Because of their height, we have to plant big bluestem and Indian grass way back from the pavement—and we have been thinking about putting those grasses in to act as snow-breaks," he reports.
Maintenance schedules are lengthier than they were in 2003. "We still have areas planted with fescue, a cool-season grass. We mow that three times a season, and the Indianapolis area gets one additional mowing. Bluestems we haven't been cutting except every few years, when we cut them down to the ground, which simulates what the plant would naturally experience on the prairie—occasional burning caused by lightning strikes. We have done some burning ourselves, but it's a legal liability, so we're reluctant to burn, especially where utility wires are present. Burning gives off hydrocarbons, which could cause arcing of electric wires."
District crews maintain from roadway shoulders to the right-of-way edge, as well as any medians. Crews also plant some areas, although the majority of planting is contracted out. "About 100 acres per year are planted in this district," Mason says. "In addition to mowing, we also control weeds with herbicide applications. We broadcast every foot of every road every other year, except in areas and interchanges where daisies and purple coneflowers have been planted. "There are also about a dozen adjacent landowners in the entire district who ask us to not mow or spray, and we honor their wishes. However, we more often get complaints that we're not spraying."
Noise complaints aren't a huge issue for maintenance crews, although some communities are beginning to install sound barriers, mainly to block traffic noise. "Fort Wayne is putting up concrete-wall sound barriers. They're not using plants or trees for that purpose, because plants, especially evergreens, don't like roadsides due to the exhaust and detritus cars produce, which can turn into toxins such as sulfur dioxide and acid rain. We also don't have any evergreens native to central Indiana, which puts trees at a disadvantage from the start," Mason explains.
Lush Flowers and "Lazy-Man's Grass"
In the southeast, North Carolina's Department of Transportation (NCDOT) uses a variety of grasses and flowers to minimize the workload. "We have a tremendous program of ornamental plantings in our state, such as wildflowers and daylilies, which all reduce mowing costs," reports NCDOT Vegetation Management Section Engineer Derek Smith. "We use turfgrass as an erosion control measure."
Unlike in some states, NCDOT, not cities or counties, is responsible for maintaining all rights of way. "We maintain 78,000 miles of right of way—interstates, primary roads, and urban streets. As part of our integrated roadside vegetation management program, some areas have been allowed to go back to nature," Smith explains. "However, some sites are still planted with grass. We can grow cool- or warm-season grasses in various regions of our state, and in the Piedmont area we can grow both. Our favorite turfgrass species? In the eastern part of the state, we're turning toward warm-season centipede grass, which requires mowing only about three times a year, whereas Bermuda and Bahia grasses need seven routine mowing cycles. However, centipede grass will sometimes require five to seven years to achieve an appropriate amount of cover before we can begin to remove any existing Bahia and Bermuda grass.
"We save about $1 million in mowing costs per year because of centipede grass," Smith continues. "It has a stoloniferous [aboveground runners] growth habit and traditionally a yellow-green color. It grows slower than some other species, so it doesn't require as much mowing. Some call it the 'lazy man's grass.' In the western area of the state, we use more hard fescue, opposed to tall fescue, because the hard variety has lower, shorter seed heads than the tall varieties. With its seed head, hard fescue reaches about 24 inches in height, whereas tall fescue can grow to 36 inches."
At present, roadside grasses now contain about 38% tall fescue, 25% Bahia, 16% bluegrass/fescue combo, 10% centipede, 6% Bermuda, and 5% hard fescue and others. "As the centipede grass matures we're able to increase its total percentage," Smith says. "In the last couple years, we have gone from 4% to 10% centipede. We project in the coming years to get the centipede share to 15%, and eventually all the Bahia will be replaced by centipede."
Native grasses also have their niche. "Around wetlands and other environmentally sensitive areas, the US Fish & Wildlife Service and other environmental agencies require NCDOT to plant native grasses, based on availability and how they will grow in that area. We also use a lot of temporary vegetative ground covers, such as rye grain, millet, Sudan grass, and German and browntop millet to establish native cover plantings. We're starting to look at using crown vetch in the western part of state, but that's only in the research stage."
North Carolina's maintenance schedule varies, depending upon what type of grass is planted. "We'll usually mow five to seven cycles per season," Smith says. "If there's a heavily maintained landscape around a business, we'll mow more. We won't fertilize an area unless the turf really needs it or there's a fertility problem in getting new growth started. Our budgets are separate line items. Maintenance is budgeted $21 million for mowing rights of way. The budget contains $1.2 million for fertilizer needs.
"We actually have two units who share the work," he goes on. "The roadside environmental unit does aesthetic plantings and weed control. The maintenance unit oversees the actual right-of-way mowing by contractors who utilize rotary and flail-type Batwing mowers or Bush Hogs. In any difficult-access areas we use utility mowers, and small mowers for rest areas and welcome centers. Maintenance does contract out 75% to 80% of the mowing; 20% is done by in-house crews."
Does NCDOT face any access issues, such as vehicle traffic on roadsides, crossing private property, or getting equipment into tight spaces? "With our cable guardrail system, we have some tight spaces on roadsides, which limits us in certain areas," says Smith. "Where traffic is too heavy, we're conscious about our contractors—safety's a big issue for us. In early 2005, a contractor was killed when he was rear-ended by a motorist on Interstate 95."
Driven by Delegation
Smith explains that the state has an unusual erosion control program. "Since the 1970s, we've had a 'delegation agreement.' We've been delegated authority by the North Carolina Department of Environment and Natural Resources [NCDENR], which allows us to design and approve our own erosion control plans. This agreement was reauthorized in 1992. We perform our own inspections, and then we're monitored by the NCDENR—checked to see if we're in compliance with all pollution control acts. This helps make sure we're doing what we should. For example, for erosion control seeding requirements, we have only 21 days to get seeds going—which, considering species and weather, may not be enough time. The department is required by NC regulations 'to provide a stabilized ground cover for exposed areas within 21 days after grading is complete or has stopped.'
"Many other states are creating their own erosion control programs to comply with NPDES [the National Pollutant Discharge Elimination System]," Smith adds. "As one of the first states in the nation to get an NPDES permit, we developed a very successful vegetation management manual that helped North Carolina get its permit. We have also offered advice to other states that has helped them get their permits as well."
Developing that manual wasn't a snap; North Carolina's climate, elevation, and soil changes were, and are, challenges. "For example, some roadsides have an 8.6 pH, while others have pH levels all the way down to 2.4, where we have used compost to help vegetation get a start. We've found lime-stabilized municipal sludge is a great liming agent for us in our 'hot rock' [low-pH] areas. These highly acidic exposed rocks can result in runoff with low pH that makes a negative impact upon the environment. To minimize that impact by neutralizing the runoff, the department has utilized limestone in roadside drainage ditches."
Anything that's applied, however, must be approved. "We work very closely with North Carolina's Department of Agriculture; they approve all pesticide and herbicide products and application methods we use. North Carolina State University also helps us train employees on applying chemicals the right way," Smith explains. "In certain areas of the state we have been asked to not treat the right of way with any chemicals, and we comply—the reasons depend upon the area. In the central part of the state, for example, we have some organic farms, so they ask us to not spray near them. We also have some endangered plant species, so we don't spray near areas where those plants are found."
As with most states, NCDOT's work is "very seasonal," taking into account that the state's higher elevations might be approaching the next season faster than other parts of the state. Smith outlines a typical spring planting: "We prepare the seedbed and add lime and fertilizer. Hydroseeding makes these ingredients easier to apply; however, a lot of contractors will add lime and fertilizer dry. The application method depends upon the site, though—on a small, level area, workers might use a broadcast spreader. In mountainous areas, hydroseeding is better because you can shoot the slurry quite a distance up slopes."
NCDOT sometimes uses herbicides for weed control. "One of the advantages of our state is that we can grow both warm- and cool-season grasses—unfortunately, weeds like the climate as well. We use EPA- and North Carolina Department of Agriculture–approved herbicides in our integrated roadside vegetation management program. Before applying any chemicals, we first survey the plot to make sure the species we don't want haven't taken over. For example, if the plot contains only 10% weeds, we won't spray; our primary weed control is mowing. Only when weeds take over or get invasive do we spray an area. Our universities know about invasive species and help us identify them; those infested areas we'll treat with herbicides." The infamous kudzu is one of those weeds. "There're about 2 million acres of it in the southeastern US," Smith notes. Also on the "top 10 invasive weeds list": Japanese knotweed, phragmites, musk, and Russian thistle.
While knocking out undesirable plants, NCDOT also does its part to aid wildlife. "We work with North Carolina Wildlife Resources Commission to maintain wildlife habitat plots for small game and bird habitats," Smith explains. "Where quail like to live, for example, we won't mow or spray. Over a period of several years, Wildlife Resources convinced several farmers living along Interstate 77 to stop mowing field edges, to give quail someplace to live. Unfortunately, there were no 'safe routes' that gave quail cover while moving from one field edge to the next, so each quail covey stayed right there in their own field edge and interbred, which was bad for the species. Our rights of way were the only pieces of land connecting all these farms, so we changed our mowing patterns in that area to give birds a safe path to get to new breeding stock."
Tackling Two Jobs With One Mow
One way to save time and money is to combine processes. Using a Brown Brush Monitor instead of a mower and a herbicide applicator gets two jobs done with one mow for Greg Ressler of Indiana's Townsend Chemical Division (TCD).
"We work with several applicators, one of them being Townsend Tree Service, which has contracts with utility companies in Indiana, Kentucky, Ohio, Michigan, Georgia, and Tennessee," Ressler explains. "Townsend Tree Service works with right-of-way managers to coordinate a vegetation program that fits their needs. This program will include herbicide application, mowing, brush removal, and side trimming. I'm called in when herbicides are part of the vegetation management program—for training, application timing, and product recommendations. Herbicide application includes high-volume foliar treatments, low-volume foliar treatments, basal treatments, cut-stump treatments, dormant-stem treatments, and tree-growth regulators. We provide site trimming and total tree and shrub removal, and often spray herbicide to inhibit any regrowth. Once a site is in shape, we'll keep it in our herbicide program, to make sure it stays that way."
For some sites in more urban settings, Ressler uses tree growth regulators in order to trim the tree less often. "Growth regulators come in especially handy if it's a backyard tree that has sentimental value to the homeowners but must be trimmed where it hangs over onto the right of way."
As for grassy or shrubby areas, spraying is less invasive than mowing, which cuts everything in its path. "We can do spot treatment with herbicides, or we can use a high-volume defoliant, which cuts down on tree growth but lets the grass grow. After such a treatment, we perhaps don't have to return to that site for four to six years."
Ressler uses Brown Brush Monitors, from Brown Manufacturing Corp. in Ozark, AL, because they allow him to spray and mow at the same time. "The machine works like a cut-stump treatment; it treats the stump at the same time a person is mowing the right-of-way areas. Almost all of the herbicide applied is brushed into the stump, with very little of the tank mix reaching the ground. This machine is very useful where trees are less than 3 inches in diameter and where a stump treatment is required. The Brown Brush Monitor reduces spray drift, since you're spraying from underneath the covered deck of the mower unit—so it's great to use where there's high public access, and around borders of the right of way. This also reduces the labor cost of treating stumps by hand, since mowing and treatment are done at the same time."
Townsend Chemical doesn't plant anything; it merely trims the wild growth. "Some people will plant trees under power lines," Ressler notes, "but they're taken out right away."
He says that two agencies, the Federal Energy Regulatory Commission (FERC) and North American Electric Reliability Council (NERC), have set guidelines that investor-owned utilities need to comply with—"they're usually the companies who own the power lines, the 'grid'"—as well as guidelines rural electric coops should comply with. "These guidelines are written to standardize line-clearing specifications. The huge power outage that occurred on the East Coast in August 2003 prompted a proactive approach to managing rights of way and line-clearing tolerances. It may appear that utility companies are getting more aggressive in right-of-way clearing. This is due to the new standards set by FERC/NERC. Government will no longer allow landowners to stop removal of trees in power-line rights of way, and it won't let trees go unchecked. There are also a lot of security issues about this; if the power goes down, will terrorists take advantage of such an opportunity?"
Ressler's firm uses more than merely hand trimming, mowing, herbicides, and other traditional methods. "We work with Purdue University to create a best management practice method of treatment for the right-of-way industry. Purdue, which has done a great job in collecting data that is useful to land managers regarding several different control methods, is now in the fifth year of a 10-year study on invasive plant control. The results of the study will be published when completed, but preliminary results have been shown at different seminars and Internet training sessions sponsored by Townsend Chemical and in conjunction with BASF. Preliminary results show that a vegetation management program that includes herbicide use outperforms other management practices without herbicide usage. Results from application methods and the choice of herbicides are more subjective due to the level of control desired by the land manager."
Along with determining a herbicide's effectiveness, Townsend Chemical seeks to discover the best time to attack an invasive plant. "For example, Amur honeysuckle takes over—it's one of the plants we try to keep under control. We do have some herbicides that will take it out, but you have to apply at the right time of year. If you make basal applications of Roundup, Pathway, and Pathfinder II in the summer or late fall, it can be controlled; however, you'll have a hard time controlling that plant in the spring."
TCD offers training classes every spring to ensure applicators are properly trained on new techniques and herbicide labels. "These classes are certified by the governing body in the state responsible for issuing certification licenses," Ressler explains. "The license is valid for five years in Indiana, three years in some other states. TCD considers training and teaching good stewardship to be very important parts of our customer service. To reduce plastic waste going to landfills, we now offer returnable, reusable herbicide containers. We also offer custom blending of products to ensure accurate application mixes of the herbicides because measuring accuracy is important."
Ressler's firm has been operating two Brown Brush Monitors for four years. "They're not street-legal; we pull them to the job site with a tractor. The machine looks like a regular Bush Hog, but you can spray with it at the same time—you don't have to, but you can. Therefore, our personnel have to be cross-trained on how to run the machine as well as on herbicide use. Although it's a terrific machine, we can't use it everywhere—sometimes we work in areas with so many hills, we have to put herbicide sprayers on backpacks and go in on foot. No matter which equipment they use, our workers are extremely careful—they live in this area and don't want to take a chance on contaminating their own water!"
Author's Bio: Janis Keating is a frequent contributor to Forester Media, Inc. publications.