by Graham Lavender
According to the U.S. Forest Service, the United States has about 770 million acres of rangelands. Over half is owned by private individuals. The federal government is responsible for management of approximately 43% of those rangelands, while state and local governments manage the remainder.1
Tangible products provided by rangelands include forage for grazing animals, wildlife habitat, water, minerals, energy, recreational opportunities, some wood products and plant and animal genes. These are important economic goods. Rangelands also produce intangible products such as natural beauty and wilderness, satisfying important societal values; often as economically important as more tangible commodities2.
The value of America’s rangelands would not be obtainable without adequate control of many brush variants that grow unprovoked, which choke out often-desired grass for grazing and soil nutrition. Running live oak (Quercus virginiana Mill) is a group of live oak varieties that will wreak havoc on the land. The brush is characterized by short, stubby growth and its location. Running live oak often forms large, dense thickets on the rangeland.
What may start out as a small growth, quickly will overtake fence lines and infiltrate grazing areas. Once this growth is out of hand, few economical options exist to reclaim rangelands. An aerial dispersant of pelleted tebuthiuron, commonly known as tebuthiuron 20P or Spike® 20P, is one way to manage running live oak.
Formulated as high-density clay pellets, tebuthiuron 20P is applied to the soil surface and is activated by water, working through the plant’s root system to achieve control. The herbicide is absorbed by the plant’s roots and inhibits its ability to convert sunlight into food (photosynthesis) effectively starving the plant. Unlike fast-acting herbicides that work on the plant leaf, the mechanism of action for tebuthiuron 20P doesn’t kill the plant immediately. Usually, the plant will defoliate and refoliate for a one to two-year period.3
Fixed and rotary-wing aircraft are best suited to apply tebuthiuron 20P to vast rangelands overrun by large brush. One example in southeast Texas is a ranch managed by the National Resources Conservation Service (NRCS) that required a rotor-wing application of tebuthiuron 20P at 10 pounds per the acre, even though a dry-prescription application is obtainable by fixed-wing aircraft with the same result.
Oligrow, LLC, an aerial application company based in northeastern Louisiana, successfully bid the contract issued by NRCS for the application of tebuthiuron 20P and began fulfillment with its Robinson R44 Raven II helicopter in early September 2016. Oligrow utilized an Isolair spreader bucket with an engine-driven slinger controlled by a hydraulic actuator attached to an Onboard Systems’ cargo hook; STC’d for the R44, capable of an 800-pound max load. Typical application height was 20 feet above the canopy with the bucket, placing the helicopter 40 feet above the ground. The R44 targeted a 95-foot swath with an application speed of 55 mph.
Some ranges can be very remote and coordination between ground crew, chemical companies and others involved in the application can be complicated. Oligrow set-up secure containers in the middle of the treatment areas to adequately secure and contain the material (required by contract). This allowed the coordination of only one delivery of material and kept the job running smooth and effectively.
Proper application of tebuthiuron 20P by air can save the landowner countless headaches from land reclamation. Less expensive than the prospect of purchasing additional land or employing personnel to manually thin the growth, brush control by herbicide enables the existing land to be utilized more effectively for years to come.
1 "About Rangelands." About Rangelands. N.p., n.d. Web. 12 Sept. 2016.
2 "Alligare - Tebuthiuron 20P." Alligare - Tebuthiuron 20P. N.p., n.d. Web. 12 Sept. 2016.
3 "Spike® 20P Herbicide." Spike® 20P. N.p., n.d. Web. 12 Sept. 2016.
