Guest post: Callie Oldfield on roadside management of rare plants.

I’m reposting an article by Callie Oldfield, a former student of mine who now works in Sewanee’s Herbarium. She describes a new collaboration between the University’s Land Manager, Nate Wilson, Physical Plant Grounds Supervisor, William Shealy, and the state agency charged with “roadside maintenance.” Many interesting and rare plants grow in the open spaces along roadsides and under powerlines. Too often they are drenched in herbicide or pulverized by mowing before they can set seed. So I was delighted to hear of my colleagues’ work and very happy to learn that other states are interested in the results of their program. I’ll let Callie continue…

TDOT and Sewanee work together to protect endangered plants on Cumberland Plateau

by: Callie Oldfield — November 04, 2015

Domain Manager Nate Wilson and PPS Grounds Supervisor William Shealy help design new management practices to protect native and endangered wildflowers growing in road right of ways.

Sewanee and the Tennessee Department of Transportation (TDOT) have been working together to protect rare plants and native wildflowers that grow along roadsides in the Sewanee area. Typically, plants growing roadside are mowed and sprayed with broad spectrum herbicides in order to prevent their growth into the road area. These herbicides eliminate the trees that pose the greatest safety threat, but they can also kill forbs and herbs, including endangered species such as Cumberland rosinweed (Silphium brachiatum).

Cumberland rosinweed is a south Cumberland Plateau endemic in the daisy family. Cumberland rosinweed can be found along US Hwy 41A, which runs through the Domain and state-protected natural area Hawkin’s Cove; this natural area was acquired by the state in 1985 in order to preserve its habitat. Other rare and unusual plants that have been subject to right of way spray in the past include: eared goldenrod (Solidago auriculata), Morefield’s clematis (Clematis morefieldii), cylindrical blazing star (Liatris cylindracea) and cut leaf prairie dock (Silphium pinnatifidum).

Domain Manager Nate Wilson and PPS Grounds Supervisor William Shealy helped spearhead this initiative to protect native wildflowers through designing new management practices. Sewanee made two recommendations: First, to allow TDOT to go off of their road right of way and into roadside Sewanee property to prune trees in a more aesthetically pleasing way that also lessens the tree’s tendency to exhibit vigorous regrowth, and second, to design a new herbicide spray formula that targeted the problem woody species while promoting grasses, forbs, and wildflowers.

For 6 months, Nate worked with a TDOT botanist and a DOW Chemical Company representative to come up with a new herbicide formula that will target only trees, because “trees are the threat [to the roads], not the grasses or forbs we are trying to protect.” The new formula will deaden only the portion of the trees touched by the spray and prevent that part of the tree from producing leaves in the spring, but will not harm forbs or herbs. As a result, fewer trees will need to be chopped or mowed, and our endangered species and native wildflowers will be protected.

TDOT sprayed this herbicide in the Sewanee-area for the first time last month and is considering adopting the practice more widely in the future.

Photos courtesy of Mary Priestly.

6 thoughts on “Guest post: Callie Oldfield on roadside management of rare plants.

  1. Liam

    I’m glad that there is collaborative work on this. Highway departments should not be in the turf management business as so many are. I do have a question, will opening the canopy by retarding the growth of leaves with herbicides have an effect on the plants below them (e.g., the rare ones mentioned)? Do they favor the microclimate the shade of the leaves provide?

  2. premodernbloke

    This is a move in the right direction. Back when the earth’s crust was cooling, Rachel Carson , in “Silent Spring”, pointed out the deleterious effects of roadside mowing and wanton use of herbicides. Here in Kentucky, I have also observed the use of bush-hog-like machines used to “mow” the low branches off of fence-row trees or trees that are not even close to the road. This practices leaves the trees subject to a myriad of diseases and is down-right ugly.

    One of the benefits of strained state budgets has been less frequent mowing. At least some of the varieties of native plants have a chance to grow to maturity before being cut.



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