FORT RILEY, Kan. -- More than 2,500 acres of native prairie on Fort Riley were a part of two different aerial spray projects to remove the plant Sericea Lespedeza and reduce woody vegetation growth around power line right of way locations Sept. 2.
The areas selected for the aerial sprays varied in size from 12 to 355 acres. These areas were selected because the terrain surrounding them was too difficult for ground crews to reach and due to time limitations to complete the sprays because of training schedules, said Jerold Spohn, agronomist, installation pest management coordinator and agricultural outlease manager for the Division of Public Works Environmental Division.
"The particular tracks that we are doing this year were chosen either because we have limited time to get into them due to training or the terrain is extremely difficult to transverse for our normal ground crews," Spohn said "They are literally scattered all over the place and range in size."
Sericea Lespedeza, commonly known as Chinese Bush Clover, is listed as a noxious weed in the state of Kansas. The plant is not native to the area, nor is it conductive to a healthy prairie habitat and ecosystem, Spohn said.
"It has been a noxious weed since 2001," said Heather Lansdowne, communications director for the Kansas Department of Agriculture Manhattan Office. "Most of them (noxious weeds) are an invasive species … With most invasive species; they take over and invade native grasses."
Prior to any spraying, whether aerial or with a ground crew, a vegetation survey is conducted by Spohn himself to determine how effective the spray would be in both quantity of Sericea Lespedeza eradicated and cost effectiveness. When doing the survey, Spohn said he also looks at the surrounding plant community and what effects the spray would have upon it. The ultimate goal is to create a balanced ecosystem.
"We want our desirable broad leaf plants, our forbs (a broad-leaved herb other than a grass, especially one growing in a field, prairie, or meadow), to have a chance to come back and reproduce," Spohn said. "We do not want to make just a pure grass land, we want a balanced ecosystem, but the Sericea is not part of that ecosystem."
While the spray will kill all broad leaf plants reached by it, he said after two years' time the plant life rebounds or increases into a healthier, better balanced ecosystem.
"From those vegetation surveys, we saw one-year post spraying, our forbs were down, but two years post spraying, we saw our forbs rebounded and in some cases even increased," Spohn said.
The second treatment performed for the power line right of way areas has never been conducted by aerial spray at Fort Riley.
The power line right of way spray kills off woody vegetation, including trees and shrubbery, to keep them from damaging power lines and block access to poles.
Additionally, the treatment helps to create a fire break around the power lines, potentially reducing the number of power poles damaged or destroyed during fires, he said.
"They're going to fly right over the center of that power line and lay down a 75-foot swath of appropriate chemical to reduce the woody vegetation underneath and close to the power lines to improve access," Spohn said.
Like the Sericea Lespedeza spray, the power line right of way spray areas were selected because of the difficultly of the terrain for ground crews to access, Spohn said.
The aircraft, an Air Tractor AT-802, which was used in both sprays, flies directly center over the power lines during the spray, controlling the spray to the area around the lines and poles only.
"Our desire is to reduce in amount the woody vegetation under there," Spohn said.
The solutions used in both sprays are safe for use around humans and wildlife, he said. They take only 30 minutes to dry, but Spohn said he prefers to be cautious and keep spray areas closed for three to four hours after.
He said he personally reviews all chemicals in the spray solutions for toxicity levels and risks and verifies their safety with the Environmental Protection Agency. The spray used for the Sericea Lespedeza is diluted down to two gallons of solution per acre.
"All the chemicals we are using are safe," Spohn said. "They have all been approved by the EPA to be used, both for the target species we are after and for the areas. They are all also registered in the state of Kansas and I have personally reviewed and approved the labels and the chemicals have also been approved by our environmental command."
Protecting water sources is one of his primary concerns during any spray, Spohn said. When creating the spray areas, he draws out 100-foot buffer zones around all water sources and areas of potential water sources.
"The one thing we are very careful about with all of our treatments, regardless of what the budget is, we try to avoid putting any product in the water," Spohn said. "Both of these projects have areas we do not treat, buffer zones … We've got roughly a 100-foot buffer zone on either side of the waterways … and I do spend a lot of time, as I put the project together, looking at those."
Spohn said he hopes to see aerial sprays for the power line right of way zones conducted every other year. At present, both ground and aerial crews spray for Sericea Lespedeza about 20 times a year to meet the state of Kansas regulations regarding the control of the noxious weed.
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