Controversial chemical pruning of branches along highways called into question

Texas Environment (Photo by Jack Dennis)

Wilting Texas tree along Hill Country highway. (Jack Dennis)

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The practice of “Chemical Pruning” by Texas Department of Transportation (TxDot) contractors to kill branches along highways with a toxic defoliant spray makes it easier to mow the right of way under trees. But some citizens are concerned about the harm to people, wildlife and environment.

Nutritionists, scientists, and researchers are troubled that influence from special interest groups, questionable politics, or powerful agricultural-chemical companies, may be getting in the way of public safety.

Llano resident Terry “Tex” Toler, was traveling in his truck in the Hill Country on Highway 29 towards Kingsland few years ago and noticed something out of the ordinary. Trees alongside the highway not far from the Llano River appeared to be dying with abnormal rotting on some branches. A minute later, he noted more failing trees “along a creek crossing, a few hundred feet from the Llano River.”

Toler contacted TXDot and “mentioned that not only was that doubling the work, adding the expense of the poison defoliant, but that the poison also affected the health of the trees, the overspray killed everything it fell on, the runoff–especially alongside every creek and draw on which they sprayed–carried the spray into the Llano River, cattle tanks, and would seep into the aquifers. To this he had no response, other than to suggest that complaints can be made to the TXDOT regional offices where the chemical pruning is taking place.”

Terry ‘Tex” Toler talks about Hill Country conservation. (Photo by Jack Dennis

Toler told friends that this chemical pruning was “courtesy of your state department of transportation. New signage along Texas roadways will soon be changed to: DON’T Keep Texas Mess With Texas.”

Research by News Legit confirmed that TxDot and the Texas Commission on Environmental Quality sought the input and expertise from agricultural and environmental scholars before making their decision on these herbicides.

The reliability of these scholars could be in question since they rely chemical manufacturers regarding their program funding and survival. Over 55.6 percent of Texas A&M’s soil and crop science department comes from private-sector donors. Monsanto, Cotton Incorporated, Chevron Technology Ventures, and others. Between 2006 and 2010, $12.5 million was donated to Texas A&M by these companies.

Defenders of these corporate donors fail to mention how universities, like Texas A&M who received $2.5 million from Monsanto a few years back to endow a faculty chair in plant breeding, may be swayed. A study by Food & Water Watch discovered that at least 15 percent of university agricultural researchers were brave enough to admit they were influenced enough by pressures from funding donors to change the methodology, design, or results of their study.

Clear Springs Lake in San Marcos, Texas (Photo by Jack Dennis)

TxDot refers to a Sept. 2012 paper from Texas A&M professor Leonard A. Brennan, Ph.D., entitled “Comparison and Assessment of Mechanical and Herbicide-Chemical Side-Trimming Methods of Managing Roadside Vegetation by the Texas Department of Transportation, Technical Report 0-6732-1  Cooperative Research Program” as a key basis for their decision on using herbicides for tree trimming.  Brennan was paid $15,000

“The project compared and assessed the mechanical and herbicide-chemical side-trimming methods that TxDOT uses to manage roadside vegetation,” Brennan wrote. “This report discusses safety, effectiveness, and economic costs of these methods.”

Brennan was quick to note that the “Environmental Impact Statement has been conducted by the TxDOT Vegetation Management Program and all the herbicides that are used by TxDOT have been evaluated. In addition, the following points must be noted: All herbicides used by TxDOT are licensed by the Environmental Protection Agency. Their application in Texas is regulated by the Texas Department of Agriculture. All are listed as nontoxic to wildlife. All herbicides used by TxDOT are applied according to labeled directions.”

It’s important to note that Brennan stated “absolute guidelines here are impossible to provide, given that various species of trees respond differently, and vegetation productivity varies tremendously across Texas.”

Rotting trees on river bank (Photo by Jack Dennis)

If the herbicides and chemicals are safe, one wonders why Brennan stated TxDot crews and contractors should “minimize use of herbicide applications for live oak vegetation control where possible. This point is especially pertinent along roadside corridors, especially in areas around or near urban and suburban zones, and on areas designated as scenic by-ways, insofar as economically and politically feasible.”

Brennan, an accomplished consultant and seeker of funding, lists on his professional resume under “RESEARCH AND EXTRAMURAL FUNDING,” numerous undertakings including receiving $15,000 from the Texas Department of Transportation in 2011 and “TxDOT, Review of Rights of Way Side Trimming Procedures $15,000.”

Brennan’s history for obtaining funding includes

  • $75,000 in 2001 from Texas Parks and Wildlife Department (TPWD): Seasonal Aspects of Discing to Improve Bobwhite Habitat: Phase 1,
  • $116,000 from TPWD for Influence of Buffelgrass on Northern Bobwhite Habitat Use and Selection in South Texas, South Texas Quail Associates Program (2001-2003):
  • $180,000, Dispersal, Habitat Area and Effective Population Size of Northern Bobwhites
  • In South Texas from TPWD for $51,700, Ecological and Economic Impacts of the Texas Coastal Prairie Conservation Initiative;
  • TPWD Department (2005) for $74,680,
  • Radar Bird Migration in the Texas Coastal Bend from TPWD in 2005 for $165,000 and more.

River in Texas Hill Country (Photo by Jack Dennis)

“Herbicides can clearly impact non-target vegetation under wrong conditions or applications,” Brennan reported. “Minimizing ‘drift’ of herbicide sprays during windy conditions, applying the absolute minimum amount of application from spray nozzles or other application techniques, are critical for minimizing the impacts of herbicides on non-target vegetation.”

TxDot has careful guidelines to insure the spraying does not drift far enough to cause damage or danger, but their manual for spraying these herbicides and chemicals admits that “Drift control agents reduce drift but do not eliminate drift. Winds above five mph may cause drift. Drift control agents reduce the fine particles created by the nozzle tip. Drift may still occur if the spray pressure is too high or the wind velocity is too great. All spraying should cease when spray patterns cannot be kept on target.”

National Weather Service states that Texas has the most diverse weather in a typical day in America (although California could be an exception on any given day). It’s not only the size of the state, but Texas’ location on the continent makes Gulf of Mexico, North Pacific and even Canadian winds are major influences to a point that it is rare to have a day in Texas with less than the required 5 miles per hour.

The average October through January (peak times for this spraying) daily wind directions and mph speeds for some select areas of Texas include:

  • Abilene   S 11.0
  • Amarillo   SW 12.8
  • Austin    S 7.9
  • Brownsville    SE 9.4
  • Corpus Christi    S 10.4
  • Dallas-Fort Worth    S 9.7
  • El Paso    SW 7.5
  • Houston    S 6.9
  • Lubbock    S 11.2
  • Midland-Odessa    S 10.1
  • San Angelo    S 9.3
  • San Antonio    S 8.3
  • Waco    S 10.0
  • Wichita Falls  S 10.7

The cost of spraying is far less expensive than sawing branches.

In Brennan’s report he stated that TxDOT’s total cost for mechanical side-trimming is $1,000 to $3,000 per mile of road side treated. He said TxDOT data concludes the herbicide application averages only $140 per mile treated, all costs considered.

The TxDOT stated average may not be correct. In the example above of Brazos County, $170,000 was contracted for 120 miles, indicating $892 average mile.

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