Arundo and Tamarix Eradication Project

Background

Arundo donax (Giant Reed) and Tamarix ssp (Tamarisk or Salt Cedar) are invasive plants that cause significant environmental and economic losses in California and elsewhere. Arundo is very flammable and, because it is shallow-rooted and top-heavy, causes bank erosion when its roots are undercut by stream action and the plants fall over, taking the bank with them. Tamarisk out-competes native plants due to its intensive water use and the salts that it exudes, which change the soil chemistry. Millions of dollars are spent annually to try to control or eradicate these two invasive plant species.

This eradication project was funded by a grant from the CalFed Bay-Delta Authority. It includes 8 partners in various watersheds in Northern and Central California, led by Team Arundo del Norte (TAdN) . It is a 3-year grant that ends in March 2009.

Project Description

Our project area is the entire length of Lindo Channel and Big Chico Creek upstream of the diversion dam at Five Mile Recreation Area. All of the Arundo and Tamarix occurrences in this area were surveyed and 218 arundo locations were mapped using the TAdN GeoWeed database protocols. The "mother plant", or original source of the infestation, is just upstream of the bridge at the Bidwell Park Golf Course. Since Arundo in California propagates only by rhizomes and nodes of the cane breaking off and floating downstream, eliminating the upstreammost occurrences is essential to the success of the project.

Within the project area,which does not include Big Chico Creek downstream of Bidwell Park, all of the Big Chico Creek Arundo is within city-owned Bidwell Park. Much of the Lindo Channel arundo is also on city-owned property, but some of these occurrences were on private property. The goal was to eradicate all Arundo on both public and private property, as Arundo left untreated can reinfest downstream properties.  However, because this is a voluntary program, landowner permission is required for any treatments on private property.

Property owners adjacent to Lindo Channel (about 350) received a letter about the project and a brochure describing the problems associated with arundo donax. Two community meetings were held to answer stakeholder questions about the need for the project, the treatment methods that would be used and the project schedule. A similar presentation was made to the Bidwell Park and Playground Commission.

Treatments and Results

The arundo and tamarisk plants were treated with a foliar application of an aquatic formulation of a glyphosate herbicide. For most of the Arundo, a single treatment was sufficient to eliminate the Arundo clump. For some of the larger areas of infestation and for plants that had previously been cut down (thus providing less surface area for the herbicide to penetrate), a second or third treatment is required. The final treatments to the remaining plants for which permission was granted to eradicate will take place in the early fall of 2008.