Response to DOT Complaints about Georgia Gardener Newsletter
Design Tip Article of August 23, 2007 (Landscaping a Slope)


In the August 23, 2007 issue of the Georgia Gardener Newsletter, I published an article entitled "Landscaping a Slope." In the last sentence of the article, I took issue with the Georgia Department of Transportation's use of two plants on slopes: Chinese Lespedeza (Lespedeza cuneata) and African Weeping Love Grass (Eragrostis curvula). The reason I took issue with this is that these two plants are known invasives in Georgia. The Georgia DOT was displeased with my article and wrote an email to Walter (not to me), which you can read here.

Now, I have issues with their email. I'm prepared to dispute their claims and cite sources that directly contradict some of their statements.

1. DOT Says Chinese Lespedeza and African Weeping Love Grass Are Not Invasive

DOT email: "Additionally, these two types of groundcovers are not listed as invasive in Georgia, as they are in states north of Georgia."

Chinese Lespedeza is a Category 1 Invasive Plant in Georgia as defined by the  Georgia Exotic Pest Plant Council. This category is for the most invasive and damaging plants such as Kudzu, Chinese Privet, Shrubby Lespedeza and Chinese Lespedeza, among others.

Interestingly, other Georgia government agencies list Chinese Lespedeza as a "serious invasive species in Georgia:"

Georgia Department of Agriculture,
Georgia Department of Natural Resources (et al.)

Georgia Forestry Commission (et al.)

Furthermore, these federal agencies recognize Chinese Lespedeza as invasive in Georgia:

USDA Forest Service along with the University of Georgia
USDA Forest Service (second site - pdf)
National Park Service
National Park Service (map)

If these state and federal agencies know about it, why doesn't the DOT?

African Weeping Love Grass is a Category 3 Invasive Plant in Georgia as defined by the  Georgia Exotic Pest Plant Council. This category is for plants that are known to grow here, have made minor invasions into certain areas or have demonstrated invasive problems in adjacent states. Other plants in this category are Queen Anne's Lace, orange daylily and annual (poa) bluegrass, etc.

Keep in mind, plants do not recognize state lines and if a plant is invasive in an adjacent state with a similar environment, it will eventually become a problem here.

African Weeping Love Grass is listed as invasive in: AZ, MD, NC, NJ, TN, TX, UT, VA and SC.

Note that Tennessee, South Carolina and North Carolina are adjacent to Georgia and have similar climates, geology and soil.

You might ask why the use of an invasive plant is a problem. The EPA estimates that invasive species cost U.S. taxpayers 138 billion dollars each year. These costs are from agricultural and horticultural losses, damage to ecosystems on public lands, damage to private property and the cost of control programs. This equates to approximately $460.00 for every man, woman and child in this country every year. Source

2. DOT is Mandated to Prevent Erosion

DOT email: "Georgia DOT is under strict mandate from EPA and EPD(*) to quickly establish a cover crop as soon as possible to eliminate erosion."

This is an absolutely true statement and I realize that the DOT is often caught between a rock and a hard place when it comes to dealing with erosion. HOWEVER...

*The EPD (Georgia Environmental Protection Division) is part of the Georgia Department of Natural Resources, the same Georgia agency that states the following (from the link above):

"Two species of lespedeza are serious invasive species in Georgia: Chinese or sericea lespedeza (L. cuneata) and shrubby lespedeza (L. bicolor)."

Sadly, I did find Georgia EPD documents that recommend using Chinese Lespedeza and African Weeping Love Grass for erosion despite the fact that their "parent" agency describes them as a pest plants:

A Georgia Guide to Controlling Erosion with Vegetation
Agricultural Best Management Practices for Protecting Water Quality in Georgia


The EPD is not the only Georgia agency that recommends the use of Chinese Lespedeza and African Weeping Love Grass for erosion control as the Georgia Soil and Water Conservation Commission has these species listed in their Erosion and Sediment Control Manual (pdf) along with the recommended seeding rates!

My conclusion to all of this would be that the state government agencies are not communicating on the topic of invasive plant species nor do they appear to be staying current with information on the federal level. Why this is, I could only venture to guess.

3. Research on Alternative Plants

DOT Email: "Georgia DOT personnel are researching various alternatives.  And, the options that we’ve discovered – Broomsedge and Blue Stem – have limited growth seasons  which would result in minimal coverage during the majority of the year." 

I've made some phone calls and sent some emails to investigate their claims of research. What I've been told (off the record) is that very little money and time have been dedicated to such projects. The total figures, I can't seem to pin down. To be fair, I did find that the DOT gave a $50,000 grant to fund at least one such research project, but since the project end date was 8/31/07 (last Friday), I don't know what the results have yielded. I would be interested in seeing all budgets and results of such research projects the DOT is funding made public as I cannot find these anywhere on their web site.

I've also been told that there are more plants than just broomsedge (Andropogon virginicus) and little bluestem (Schizachyrium scoparium) that show promise as alternative plants. Georgia has many native grasses and perennials that thrive on disturbed sites, germinate quickly and would make excellent alternatives to non-native invasive species. If you wish to look at a comprehensive list of potential alternatives compiled by Connie Gray, Landscape Architect and President of the Georgia Exotic Pest Plant Council, it can be accessed here (pdf).

The problem of quickly covering slopes and bioinvasion is not unique to Georgia and the topic has been discussed repeatedly in trade journals and at conferences. One valid complaint is that seed sources for natives can be in short supply. However, other states seem to be making progress....what about Georgia?

I don't expect the DOT to go out overnight and completely eliminate their current erosion control practices, but I would like to see some progress being made away from these plants by phasing in the use of natives. Other than the DOT's Wildflower Project, I'm not seeing natives being used on our roadsides.

What I would like to see immediately is the suspension of using Chinese Lespedeza and African Weeping Love Grass (and all listed invasives) along roadsides that pass close to environmentally-sensitive areas.

Lespedeza hill along I-85African Weeping Love Grass

4. The Math of the Matter

DOT Email: "Furthermore, Ms. Schrum’s information on the ratio of slopes is inaccurate..., her slope degrees are not correct. It is correct to list horizontal distance of the slope before the vertical height in a ratio; Ms. Schrum’s column lists it as opposite."

This statement is partially correct. While I did make a typo and reverse the slope ratios on the first two slopes originally listing them as 1:3 and 1:2 instead of 3:1 and 2:1 (which has been corrected), I dispute that my slope degrees are not correct.

For those a bit rusty on the calculations of slope, the correct way to determine slope in degrees is to determine the arc tangent of the rise (change in altitude) over the run (change in distance). So.... here is how it would go:

Slope 3:1, the rise = 1, the run = 3, therefore the angle in degrees is the arc tangent of 1/3 = 18.4... (I said less than 20 degrees).

Slope 2:1, the rise = 1, the run = 2, therefore the angle in degrees is the arc tangent of 1/2 = 26.6... (I said 20-45 only to make it a convenient range).

Slope 1:1, the rise and run both = 1, therefore the angle in degrees is the arc tangent of 1/1 = 45.0 (I said 45 plus).

The ranges I gave were only to make calculations for homeowners easier. The landscaping strategy outlined for each slope is correct and was actually originally stated in a conversation with a Landscape Architect who works for the DOT. Besides, I consider this to be a minor issue in the overall argument being made by the DOT.

5. My "Tactics"

DOT Email: "...in the 8/23 issue of “The Georgia Gardener,” Georgia DOT landscaping tactics and strategies were attacked in an unprofessional manner by a colleague."

It continues: "Walter, we request that Ms. Schrum’s tactics be addressed in an effort to preserve the integrity of this highly-regarded E-newsletter. "

Was my approach in calling them "geniuses" a bit curt - absolutely! However, for the past 4-5 years I have sent emails and letters to the DOT expressing my concern for the use of such plants on roadsides. I'm not alone. Other professionals worried about the use of non-native invasive plants along roadsides by the DOT have expressed their concerns verbally and in writing. Prior to this newsletter article, I never received a response and I don't believe my colleagues have either.

I'm sorry that it took such a blunt and forceful approach to get their attention and cynically, I'm not sure they would have replied at all if The Georgia Gardener Newsletter wasn't so widely distributed and associated with a successful radio program.

Perhaps some positive change can come from this exchange.

6. What can YOU Do?

If the use of known non-native invasive plants concerns you, especially since we'll have to address their use and spread with your tax dollars eventually, I would write to the DOT:

Georgia Department of Transportation
Harol Linnenkohl, Commissioner
2 Capitol Square, SW
Atlanta, GA 30334
(404)656-5267

OR use their online comment form which is accessible under "Contact Us" from their main web site page.


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