Update: Utah Tamarisk Control Project Gets Results

Strong partnerships and long-term commitment is key to success

NOTICEABLE CHANGE in the Buckhorn Wash landscape is one measure of success observed by locals who are returning to recreate in the Wash where saltcedar has been removed (top left).

RALPH WHITESIDES, Weed Extension Specialist at Utah State University demonstrates sprayer calibration methods to volunteers (top right).

VOLUNTEERS share a laugh as they set out to search for and treat regrowth from saltcedar plants (bottom left).

FOLLOW-UP EVALUATIONS of the site produced only one tamarisk plant out of 500 that had regrown. Most treated plants looked like this one (bottom right).

Buckhorn Wash, a long, steep-walled canyon located in Central Utah, is renowned for its spectacular scenery, watershed value, and extensive Native American rock art. “Invasion of tamarisk (Tamarix ramossisima, also known as saltcedar) in Buckhorn Wash is a priority for land managers tasked with protecting the area’s important resources,” explains Ralph Whitesides, Weed Extension Specialist at Utah State University. 

In June 2008, ArrowCorps5 Scouts, volunteers, and city, state, county and federal agencies joined forces to treat over 46 linear miles of tamarisk within three project areas. The five-day project involved a total of 400 Scouts, 110 agency personnel, and 50 volunteers. 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.

Partners in the project realized that long-term management was critical to stop reinvasion of tamarisk. Since the initial effort in 2008, members of the Skyline Cooperative Weed Management Area (CWMA) have conducted an annual monitoring and retreatment program in Buckhorn Wash. 

“Ten members of the CWMA spend one day each year applying a 25 percent solution of Garlon® 4 Ultra herbicide mixed with methylated seed oil to treat tamarisk regrowth within the project area,” says Whitesides. “Their long-term commitment to the project has proven successful.”

Utah State University has periodically measured the status of the control effort since 2008. Results of their evaluations 12 months after treatment showed a reduction in tamarisk canopy of 97.5 percent. In April 2013 (five years after treatment), Whitesides returned to Buckhorn Wash to measure long-term control of tamarisk. 

“Our monitoring plan was to evaluate regrowth on 500 tamarisk plants within the project area along 10 miles of the wash,” he explains. “We were prepared to measure and count, but instead found only one tamarisk plant out of 500 that had regrowth. This one plant had six stems ranging in length from eight to 50 inches, equivalent to 99.98 percent reduction in canopy five years following the initial control program. The tamarisk control project in Buckhorn Wash is incredibly impressive in both the level of control achieved and commitment by the CWMA.”

COST OF RETREATMENT. Whitesides calculated the cost of the tamarisk retreatment program at $1,595 per year or a total of $7,975 over the five-year period. Cost assumptions were based on discussion with CWMA members and are shown in Table 1.

Tamarisk canopy within Buckhorn Wash originally encompassed about 11.9 canopy acres with plants scattered within the 13,850-acre project area. Excluding costs of the initial treatment program ($157,000 agency funding and grants), the cost of follow-up treatment to protect the Wash from tamarisk reinvasion was $0.58 per acre.

In addition to mechanical and herbicide treatments, the Diorhabda beetle (Diorhabda elongata deserticola) released on private land for biological control of tamarisk has expanded its population into the Wash. The establishment of the beetle along with continued monitoring and control efforts will help ensure complete control of tamarisk in Buckhorn Wash. 

It took great vision on the part of the Skyline CWMA (which included support from Bureau of Land Management, U.S. Forest Service, and the Emery County Weed Program) to recognize and pursue a partnership with the ArrowCorps5 Scouts. The CWMA’s commitment to a long-term monitoring and retreatment program helped assure the high level of control within the project area.


SALTCEDAR AND RUSSIAN OLIVE MANAGEMENT features recommendations for managing saltcedar and Russian olive with herbicides. Learn tips and techniques for cut stump, foliar, and low volume basal bark applications. Plus, learn when and how to use Vastlan® and/or Garlon® 4 Ultra. 


Herbicide product (active ingredient) mentioned in this article include Garlon 4 Ultra (triclopyr). 

®™Trademark of The Dow Chemical Company (“Dow”) or an affiliated company of Dow.  Milestone and Vastlan are not registered for sale or use in all states. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your state.

Milestone: When treating areas in and around roadside or utility rights-of-way that are or will be grazed, hayed or planted to forage, important label precautions apply regarding harvesting hay from treated sites, using manure from animals grazing on treated areas or rotating the treated area to sensitive crops. See the product label for details. State restrictions on the sale and use of Milestone apply. Consult the label before purchase or use for full details.

State restrictions on the sale and use of Garlon 4 Ultra apply. Consult the label before purchase or use for full details. Always read and follow label directions. ©2019 Corteva. 

Published September 2013; tradmark updated June 2019.