March-April 2006

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Vegetation Management More Is Less

As gasoline prices rise, more states are using grasses and forbs that require less maintenance.

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By Janis Keating

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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.

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"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.'
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