Borrego Knows Best

San Diego County Board of Supervisors agreed Borrego Knows Best when it made its final determination on Rudyville on September 12, 2018.

Check out our campaign video, Borrego Knows Best

KPBS Televised Broadcast

TCDC supporter, Michael Bovee, produced the following video describing one aspect of TCDC’s response to the threat produced by Sahara mustard. This report was broadcast on KPBS television and radio on June 18, 2014.

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Sahara Mustard
Life Cycle Slideshow

Learn how to recognize invasive Sahara Mustard from seeds and tiny sprouts to large, mature plants.

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"Never doubt that a small group of thoughtful, committed citizens can change the world. Indeed, it is the only thing that ever has."

— Margaret Mead

 

"Don't wait for the cavalry to come over the hill to save you. You are the cavalry and had better save yourselves."

— Robert Lee Paul

Glyph of Sun

 

Tubb Canyon Desert Conservancy

Summer 2019

Sahara Mustard

When the neighbors on Tubb Canyon Bajada came together in 2011 to do battle with Sahara Mustard (Brassica tournefortii), it was not immediately clear what would be required to protect pristine desert habitat from this aggressive foreign invader. We began by manually removing as many Sahara mustard plants from as many acres as we could, and then surveilling those acres every winter and spring. These efforts have resulted in many acres of pristine dessert habitat in southwest Borrego Valley that are now free of Sahara Mustard; however, the problem turned out to be much larger than we knew.

Large quantity of bagged Sahara Mustard

Bags of Sahara mustard from the Tubb Canyon Bajada delivered to the Sahara Mustard dumpster formerly provided at the Headquarters of the Anza-Borrego Desert State Park on March 27, 2011.

By 2013 we learned that in the century since its accidental introduction in the arid, date-growing Coachella Valley of California, Sahara Mustard had spread up the California coast, as far north as San Luis Obispo County; eastward across Arizona, and New Mexico to west Texas; and from southern Nevada and Utah southward into central Mexico. We learned that with this broad extent of dispersal, manual eradication and herbicides would never be effective in ridding the deserts of the American Southwest of this destroyer of native vegetation. We learned that Sahara mustard was an ecosystem-level problem and concluded that the only feasible solution for solving a problem of this scale would be the development of a biocontrol agent — a natural predator against Sahara Mustard—that could be safely released into the environment of the southwestern United States to stop, and hopefully reverse, Sahara Mustard’s expansion and destruction of fragile habitat and biodiversity.

With the goal of discovering a biocontrol agent, we partnered in 2014 with researchers from the University of California, Irvine to map a course toward the discovery of such a biocontrol agent. This effort would make use of the latest genome sequencing technology to shave years and millions of dollars of cost off the project. The course we plotted is described in our White Paper titled “Seeking Biocontrols to Enable a Long-term Solution for Sahara Mustard (Brassica tournefortii) Invasion in North American Deserts.”

Phase I of the project began in 2015 and consisted of genomic sequencing hundreds of Sahara Mustard samples taken from throughout the southwestern United States. Completion of Phase I demonstrated three distinct populations of Sahara Mustard in the deserts of the Southwest, and thus three distinct introductions of this invader from the Old World. Phase I was the doctoral work of Daniel Winkler, Ph.D. and was published in Ecology and Evolution in June 2019 under the title “Multiple Introductions and population structure during the rapid expansion of the invasive Sahara Mustard (Brassica tournefortii).”

Dr. Winkler, in concert with colleagues at the USDA’s European Biologic Control Laboratory in Montpellier, France, are nearing the completion of Phase II of the project. Phase II involves the genomic analysis of samples of Sahara Mustard from its native range around the Mediterranean and into the Near East. Comparing the results of Phase II with those of Phase I will reveal exactly where in its native range the Sahara Mustard that was introduced into the United States in the early 1900’s came from. The importance of this discovery is that it will remove the guess work of where to look in Sahara Mustard’s enormous native range for potential predators already adapted to keep Sahara Mustard in check.

With the foundational work nearly completed, and with dozens of Parks, NGO’s, agencies, and academic institutions attesting to the importance of discovering a biocontrol agent for Sahara Mustard (http://bit.ly/2IB5aBw), in June 2019 the USDA deemed Sahara Mustard to be a priority in its 2020-2025 Action Plan. Such a designation sets the stage for the third and final phase of our program: the identification of potential pathogen(s) and/or predators against Sahara Mustard from its native range, and the testing of these potential pathogen(s) and/or predators for safety and efficacy for future release in order to suppress the epidemic of Sahara Mustard in the deserts of the American Southwest.

While the identification and testing of potential pathogens against Sahara Mustard will take several more years, we are more than half way to our goal of discovering a way of confronting Sahara Mustard on an ecosystem level. None of this would have been possible without our brilliant and tenacious researchers and our generous supporters. I give my heartfelt thanks to everyone who has worked so diligently to get us this far. Please stay tuned and involved in the continuation of this important project!

J. David Garmon, MD
President, TCDC

 

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