TAMARISK/ARUNDO/ ERADICATION/CONTROL PROJECT

The Mojave Desert RCD is continuing their invasive plant removal/retreatment program with the focus remaining on retreatments in the Mojave River. Over the years the Tamarisk Beetle (Diorhabda) has been slowly migrating its way along the Colorado River and can now be found across the California border and along the Mojave River. Due to the migration of this little beetle the District decided in the fall of 2019 to not treat the usual places and give the beetle a chance to proliferate. Retreatment at Camp Cady in Newberry Springs was paused again this year as well to allow the tamarisk beetle to settle and proliferate.

 

With bio-fund trust funding through MWA the District has enlisted the services of Dr. Tom Dudley with Restoration Science LLC in Santa Barbara, to monitor the Saltcedar Biological control for the Mojave Basin. In August and November of 2020 and again in early June of 2021 Dr. Dudley and his team surveyed the Mojave Basin for Diorhabda (tamarisk beetle) along the Mojave Riverbed. There has been extensive dispersal and establishment of the beetle in 2020 and the beginning of 2021. Beetles have been found to exist at Camp Cady in Newberry Springs and along the I-40 half-way between Newberry Springs and the Lava flows. Next generation beetles were in large numbers in the tamarisk at the Marine Corps depot in Barstow and have survived the winter along the riverbed in Hinkley and Oro Grande. Due to the dry season the tamarisk beetle was not out in force by the end of June 2021, but signs were still visible of successful overwintering. According to Dr. Dudley the dry season will only delay the full force of the beetle until later in the summer. The District will follow the progress of the beetle and monitor the various tamarisk spots where they show the most sign.The Diorhabda doesn’t kill the tamarisk plant but puts it in a suppressed state where it will not produce seed and thereby cannot spread. The hope is while the tamarisk plants are in this suppressed state native vegetation will rehabilitate the areas along the riverbed, using less water and providing habitat for native endangered wildlife.

 

The District began control of these invasive plants during 2008 and has currently treated the majority of infested acreage from south of the Mojave Forks Dam to ½ mile east of the Barstow Marine Base. Parcels of non-consenting landowners and critical erosion areas have 3been avoided. To date, a total of 2,310 “weed” acres of a total of 10,000 assessed acres of these invasive species have been removed/controlled.Chemical retreatments will be on-going in areas where the beetle is not established to make sure all weeds stay eradicated, and any new sprouts are treated before they go to seed. However, if the tamarisk beetle continues to proliferate within the salt cedar in the Mojave River, the need for chemical treatment may not be as necessary.Initial funding for removal efforts was provided by a USDA NRCS earmark of funds to the Mojave Water Agency, the Mojave River Basin Adjudication’s Biological Resources Trust Fund, State Proposition 50, and direct funding from the Mojave Water Agency.

 

Benefits of this program are:

  1. Implement the Mojave Basin Area Judgment (improve riparian habitats, maintain ground/surface water saturation at root zone, increase downstream flows).

  2. Reduce evapotranspiration of ground and surface waters (water conservation).

  3. Reduce salt deposits in the riverbed (water quality).

  4. Reduce wildfire potential.

  5. Keep channels open – reduce debris damming and severity of flooding.