INVASIVE SPECIES ERADICATION

Staff and volunteers of the Kern River Preserve have spent over a decade fighting invasive species. These efforts have paid off with one of the most native forests in western North America.

Last year staff of the Kern River Preserve and the California Department of Fish & Game spent time eradicating invasive weeds from the South Fork Watershed.

Each of us can help prevent the spread of invasive plants and animals. You can help by learning which species can become invasive and eradicate these from your own yards. Help to educate your local nurseries about the problem with invasives and get them to stop selling problem plants. Contact your legislator and local agriculture commissioner to make sure no invasives are sold or promoted in your county or town.

The article that follows is a tutorial on salt cedar: one of a series of articles staff of the Kern River Preserve are preparing to educate about local invasives and some steps each of us can take to help eradicate them.

SALT CEDAR

Four invasive Tamarix species have been identified in California: T. ramosissima, T. chinensis, T. gallica, and T. parviflora. All four are many-branched shrubs or trees less than twenty-six feet tall with small scale-like leaves, from which comes the name salt cedar. Leaves have salt glands, and salt crystals can often be seen on leaves. Small white to deep pink flowers are densely arranged on racemes. The bark is reddish brown with smooth stems less than an inch in diameter.

Identification

* Shrub or small tree, 5 to 20 feet tall.
* Pale green leaves are small and scale-like, on thin stems with many branches.
* Flowers pink to white in color, appearing from spring to late summer.
Identification key in: Hickman, J. ed. 1993. The Jepson Manual: Higher Plants of California. University of California Press.

Habitat and local distribution

* Well-adapted to alkaline soils, wind, and a wide range of temperatures; typically found along waterways.

Impacts

* Excludes other plants from growing underneath, due to salt deposited from leaves.
* Aggressive root system depletes ground water needed by native species.

Prevention and Control
Prevention

* Plant natives or spread native seed in disturbed areas.
* Search threatened areas regularly (at least annually) to look for newly arrived plants.

General control notes

* Difficult to eradicate since species spreads rapidly and usually resprouts after treatment. Follow-up monitoring to treat resprouts essential (Lovich 2000).

Manual or mechanical control

* Root plowing and cutting—useful for initial removal of heavy infestations; follow-up application of herbicides suggested to treat resprouting.
* Estimated costs: vary depending on if volunteers conduct removal and on the plant density; equipment costs range may from $100 to over $1,000. There may be additional fees for disposal of plant material.
* Pulling by hand—uprooting of seedlings and small plants.
* Prescribed burning—useful for reducing biomass prior to herbicide application.
* Flooding—effective when thickets can be flooded for one to two years.

Biological control

* Biological control agents—USDA currently testing several insect species from other countries for release in United States.
* Grazing—cattle grazing can reduce amounts of sprout regrowth.

Chemical control (Lovich 2000)

* Apply triclopyr (as Pathfinder II®) to bark of smaller stems (< 4-inch diameter); wet bark at base of stem prior to herbicide application.
* Treatment of resprouts by glyphosate (Rodeo® or RoundupPro®) or imazapyr (Arsenal®) during growing season; only Rodeo® is registered for aquatic habitats.
* Estimated costs: costs for materials and application by a contractor are approximately $250 per acre for glyphosate, depending on size of treatment area, scale of treatment, and herbicide dosage. It is recommended to contract a licensed professional for herbicide applications (Gibbons et al. 1999).

Integrated control

* Cut larger shrubs and apply triclopyr (as Garlon 4® or Garlon 3A®); use of Garlon 3A® most effective when applied during growing season (Lovich 2000).

MANAGEMENT IN HOME LANDSCAPES

Prevention is the best management strategy for avoiding problems with salt cedar in and around home landscapes. If salt cedar is found growing in landscaped areas, immediately pull the plant before it can spread. Pulling plants (try to remove as much of the root as possible) is an effective way of controlling a few scattered plants growing within landscaped areas. Use of a broad-leaf herbicide is another option but care must be taken to avoid injuring nearby plants.

MANAGEMENT IN PASTURES, RANGELAND, RIGHTS-OF-WAY, AND CROPS

Established salt cedar populations are difficult to control and require multiple years of intensive management. Removing all woody material is essential as the plant can resprout from twigs. A management program should include prevention, monitoring, and treatment of small satellite populations before plants develop extensive roots. Make sure root fragments and seed are not transported to other sites. Always clean vehicles, machinery, and clothing after visiting infested areas.

References and more information

DeLoach, C.J. 1997. Biological control of weeds in the United States and Canada . In: Luken, J.O and J.W. Thieret (eds.). Assessment and Management of Plant Invasions. Springer-Verlag , New York , NY.

Gary, H.L. 1960. Utilization of five-stamen tamarisk by cattle. Rocky Mountain Forest and Range Experiment Station. Research Notes. 51:1-3.

Gibbons, M.V., M.G. Rosenkranz, H.L. Gibbons, Jr., and M.D. Sytsma. 1999. Guide for Developing Integrated Aquatic Vegetation Management in Oregon. Center for Lakes and Reservoirs, Portland State University, Portland, OR.

Lovich, J. 2000. Tamarix spp. In Invasive Plants of California Wildlands. Carla C. Bossard, John M. Randall, Marc C. Hoshovsky, Editors. University of California Press. Available at
http://www.cal-ipc.org/ip/management/ipcw/index.php .

A Success Story: Tamarisk Control at a Coachella Valley Preserve, Southern California. T. Martin. 2001. The Nature Conservancy, Wildland Invasive Species Program. Available at http://tncweeds.ucdavis.edu/success/ca003/ca003.rtf.

Element Stewardship Abstract for Tamarix ramosissima Ledebour , Tamarix pentndra Pallas, Tamarix chinensis Loureiro, Tamarix parviflora De Candolle, salt cedar, tamarisk. A.T. Carpenter. 1999. The Nature Conservancy, Wildland Invasive Species Team. Arlington, VA. Available at http://tncweeds.ucdavis.edu/esadocs/documnts/tamaram.pdf .