Example 35 : NCDOT Roadside Vegetation
Management Guidelines in Marked Areas
- No mowing April 1-November 15.
- No herbicides, no fertilizers. ( Exceptions can be made for herbicides under
special circumstances, discussed below. )
- Mowing from November 16-March 31 is allowed and, in most cases ( *see exception
below ) , should be done at least every other year. Winter mowing every
year is acceptable. If regular contract mowers are unable to mow the sites under
this time frame, NCDOT mowers may be used during the winter.
- Mowing should not be conducted when the soil is wet, as compaction and rutting
will occur.
- In some instances, rare plants may be growing right along the edge of the road.
Ideally, the plants should be protected if at all possible in this situation, but
if NCDOT division staff determine that the road shoulder should be mowed during
the growing season for safety or visibility, then the shoulder may be mowed accordingly.
If possible, an NCDOT biologist can visit the site and mark where individual plants
are, so they can be avoided.
- NCDOT mowing contracts are under modification to ensure that contractors are
responsible for finding out if any endangered plants are within the areas they will
be working, and for avoiding injury to the plants. The County Mowing Inspector or
the Division Roadside Environmental Engineer should review the No Mow policy with
each county maintenance office and mowing contractor prior to any mowing activities
on roads with rare plant populations.
- The standard mowing height is usually four inches; ideally, the mower should
be set at a level to avoid scalping the ground and damaging rare plants.
- Clippings from winter mowing should be left on site so any rare plant seeds
produced will have the opportunity to germinate within the population. An exception
can be made if only weeds are reproducing.
- Prior to entering the site, mowers and equipment should be cleaned off, removing
any accumulated vegetative debris that contains weed seeds.
- Rare plants along roadsides often extend into utility line ROWs. Utilities managing
plant growth in DOT ROWs must be told that herbicide use on DOT ROW is unlawful
without a permit. Utilities conducting plant management adjacent to DOT
ROWs should be notified when rare plants are present.
* Mowing Exception
There is an exception to winter mowing for Virginia spiraea. This shrub is found
along streams, rivers and roadsides in the mountains. Because it is a woody shrub
it should never be mowed, regardless of the time of year. Trimming
or selective thinning of other woody vegetation that compete with this species may
be recommended for management.
Signs/Stakes
When rare plants are discovered on NCDOT's ROW, the population should be marked
with ‘Do Not Mow' signs. These signs should be large enough to be easily noticed
by roadside mowers. A variety of signs have already been placed along roadside populations;
most simply state, ‘Do Not Mow' while others include dates for the no mow
period ( April 1 - November 15 ) , or add ‘Do Not Spray.' To ensure that signs
are readily understood by a variety of workers, signs with universal symbols for
‘Do Not Mow' and ‘Do Not Spray' are under review for future use.
Do Not Mow signs should be positioned at both ends of a population, facing so mowers
will see the signs as they approach the No Mow area. Where rare plants occur along
a significant stretch of roadway it is suggested that double sided Do Not Mow signs
be placed periodically along the population - two Do Not Mow signs placed back to
back on a single post. The reasoning for this is that if a sign at one end of the
population disappears, the mower will encounter another Do Not Mow sign before the
entire population is mowed. Maintaining the signs and seeing that they are visible
and in good condition is critical in order to protect these populations. Damaged
or missing signs should be replaced as soon as possible, especially during the growing
season. If possible, signs should be placed at a low enough level for the mower
operator to see.
White-topped wooden stakes can also be useful in alerting mower operators that the
site is designated as a No Mow area. These should be used in addition to ( not instead
of ) Do Not Mow signs. The wooden stakes are approximately 40 inches long with the
top six inches painted white, the same stakes used to delineate mowing patterns
and areas that are off limits to mowers. Stakes should be placed at regular intervals
along the entire edge of the roadway side of the population.
Encroachments/Maintenance
Division environmental officers, district offices and maintenance units should
make sure rare plant sites are taken into consideration for proposed ROW encroachments
and maintenance work. ROW encroachments such as driveways, utility work, minor widenings,
installation of utility lines and pipes for driveways have the potential to damage
rare plant populations. All ROW access requests and driveway access applications
in areas where rare species are known to occur should be reviewed to ensure there
will be no impacts. If impacts to rare plants are likely to occur, efforts should
be made to avoid or minimize damage. District offices should maintain secondary
road files with a notation to remind them that the road has a protected species.
Roadside maintenance activities, such as grading and ditch maintenance can also harm
rare plants. As above, if impacts to rare plants are likely to occur, efforts should
be made to avoid or minimize damage. Heavy equipment should be kept out of rare
plant areas during the No Mow period. Employees working in the area should be shown
the rare plant so they can avoid damaging them.
Herbicide Use
To reduce competition from invasive weeds, herbicides should only be used when
mechanical removal is not an option. Herbicides can be used near rare plant populations
when specifically prescribed by someone familiar with the biology of the rare plant.
Two main herbicides have been recommended for use on roadside rare plant populations.
These herbicides have been tried in a variety of situations by NCDOT and are believed
to be most suitable for managing these sites, glyphosate triclopyr for woody vegetation.
All herbicide applications for roadside rare plant sites should be conducted by
a Licensed Pesticide Applicator.
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