Scouts Team-up Against Tamarisk

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Once a refuge for outlaws and fugitives, Buckhorn Wash, a long, steep-walled canyon is renowned for its spectacular scenery and extensive Native American rock art. Located in Centra Utah, the canyon serves as the main northern gate-way to the San Raphael Swell, one of the state’s fastest growing tourist destinations. The area’s canyons, mesas, and buttes also provide critical habitat for rare plant species, desert big horn sheep and other wildlife. 

The easy access and abundance of scenic, historical, archeological, and recreational resources makes Buckhorn Wash unique. “It is a beautiful area that is rich in history. It contains dinosaur foot prints, pictographs from the Native Americans who once lived there, and is notable for its use by Butch Cassidy and the Wild Bunch in the days of the Wild West,” says Dr. Ralph Whitesides, Weed Extension Specialist at Utah State University. “Invasion of tamarisk (Tamarix ramossisima, aka saltcedar) in this and other scenic canyons is a real concern to land managers wanting to protect the visual, cultural, and wildlife resources of the area.”

In 2004, land managers with the Manti-LaSal National Forest (USFS) initiated “Push Back the Tammies” a project to control tamarisk in the canyons of Central Utah. They enlisted the aid of the Boy Scouts of America’s leadership corps, the Order of the Arrow. To mark their Centennial Celebration, the Scouts accepted the challenge as one of five nationwide service projects, dubbed the ArrowCorps5. “Once the Scouts accepted the project, the USFS contacted us to join the effort,” says Karl Ivory, Rangeland Management Specialist with the Bureau of Land Management (BLM) Price Field Office. “There is a lot of tamarisk in our canyons in Central Utah, but we knew that with enough resources we could impact infestations in priority areas like Buckhorn Wash.”

Release of the Diorhabda beetle for biological control of tamarisk is not allowed on federal lands in Utah, thus mechanical treatments and herbicides are used for controlling the plant. Three canyons were identified for the tamarisk control effort, two on USFS land and Buckhorn Wash on BLM land. “We knew we had a lot of planning to do before the Scouts came to help with the control program scheduled for 2008,” explained Ivory. “We worked closely with other city, county, state and federal agencies, and the Skyline Cooperative Weed Management Area (CWMA) to organize the project. One of our first field objectives was to map the infestation using GPS technology so we would know location and distribution of tamarisk and how many acres we needed to treat. We mapped the side drainages of Buckhorn Wash in 2007, and Utah State University mapped the main-stem canyon in 2008. Once we had this information it made it easier to organize resources and materials to implement the control effort.” Detailed mapping also allowed agencies to closely monitor results.

The cooperative group tested various herbicides and application methods. “I worked with ArrowCorps5 leaders and BLM in Buckhorn Wash in the summer of 2006 and 2007 to determine what herbicide treatments and application methods would be the most effective on tamarisk,” says Whitesides. “Our treatments included glyphosate, Habitat™, and triclopyr as Garlon® 4 Ultra (also sold as Remedy® Ultra in some states). Although there was activity on tamarisk from all herbicides, we had the best results with Garlon 4 Ultra which is what we ultimately used in the control program in 2008.”

In June 2008 about 400 ArrowCorps5 Scouts from across the United States came to central Utah to join forces with other volunteers. An Incident Command System was established to organize the nearly 560 individuals involved with the control project. Canyon View Junior High School in Huntington, Utah serving as the command center. It also served as the campground for Scouts during the five-day project. Utah State University and agency staff trained Scouts on plant identification and safety in using clippers to cut, remove and scatter tamarisk branches above the high water mark prior to herbicide treatment. Experienced sawyers with USFS and BLM were used to remove larger diameter tamarisk with chainsaws. Licensed herbicide applicators with various agencies and licensed volunteers received training in herbicide application. Since sawyers were leaving 12 to 16 inches of stem above the ground line for treatment, the method they used was a modified cut stump application (similar to a low-volume basal bark application except that the above ground stems are removed) with 25% v/v Garlon® 4 Ultra in basal oil. 

In the end, over 46 linear miles of tamarisk was controlled within the three project areas. “What an effort!” says Whitesides. “The commitment of these people was amazing, and they all took home lessons they learned from the project including the value of partnerships, GPS mapping techniques, tamarisk management methods, and a deep appreciation for protecting a resource from invasive non-native plants. This control program would not have been possible if it had not been for the volunteer Scouts. They did a great job, we didn’t have any on-site accidents, and we had very successful tamarisk control.” 

When the control project concluded, tamarisk plants within 13,850 acres of U.S. Forest Service and Bureau of Land Management land had been treated and controlled. “We knew it was critical to follow-up our efforts to see how successful the treatment program was using our volunteers,” says Ivory. Utah State University conducted evaluations 60 and 90 days after treatment in Buckhorn Wash and measurements showed 95 to 99% control of tamarisk. The area was remapped in 2009 12 months after treatment to measure changes in acres infested. The 2009 survey found a reduction in total canopy of 97.5%. Re-growth on remaining tamarisk was treated late in the season (mid-October) in 2009 by members of the Skyline CWMA (which includes local, state, and federal partners) using foliar treatments of a 1% v/v solution of Garlon 4 Ultra in water. Treatment of tamarisk re-growth in Buckhorn Wash involved 230 hours in 2009 compared to 9,440 hours in 2008. In September 2009, the Skyline CWMA received the BLM National Rangeland Stewardship Award for their collaborative efforts on the tamarisk control program.


“The BLM is committed to maintaining and expanding the tamarisk control effort in Buckhorn Wash. We have funding for the next four years to continue monitoring and treating re-growth which combined with the excellent control we have now, should ensure long-term success of the project,” says Ivory. “We also have interest from the local Boy Scouts to continue this project, and we are expanding our initial control efforts upstream and in high use recreational sites along the canyon. It’s a lot easier to expand on this initial project than it is to start in a heavily infested area.”

“The greatest benefit from the project was partnerships formed among 22 different state, city, county, and federal agencies that collaborated with the project, and the new and improved relationships that we developed with other people in Utah who are concerned about weeds.” Ivory and Whitesides agree. “There was a tremendous educational benefit for everyone that worked on the project. The secondary benefit is that we covered a large area and now we can keep tamarisk in check with a local crew,” says Ivory.


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