Author
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Deloach Jr, Culver |
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Submitted to: Proceedings Saltcedar Management & Riparian Restoration Workshop
Publication Type: Proceedings Publication Acceptance Date: 1/30/1997 Publication Date: N/A Citation: N/A Interpretive Summary: The invasion by the exotic shrub saltcedar (Tamarix ramosissima) from the Middle East is perhaps the most serious biotic threat ever to befall the river valleys of the western United States. Biological control has a long history of safe and effective control of many weeds in the United States and many other countries. The introduction of the insects that control saltcedar in Asia can be effective, safe, highly selective so as not to damage other plants, and relatively inexpensive. It will not eradicate saltcedar but it can reduce it below the threshold of damage. Several insects offering promise of control have been found on saltcedar in the Middle East. Testing has been completed for two species, a mealybug from Israel and a leaf beetle from China. Release awaits approval of a Biological Assessment with the U.S. Fish and Wildlife Service and an Environmental Assessment (both in preparation). The expected 75-85% control will require the introduction of several insects over a 5- to 10-year period. This is expected to significantly improve the river valley natural ecosystems, including endangered species, increase groundwater levels for agricultural and municipal use and reduce wild fires, flooding and soil salinity. Technical Abstract: The small tree saltcedar (Tamarix ramosissima), native to the Middle East, has invaded riverbottoms and lake shores of the southwestern United States. It forms dense thickets that displace the native vegetation; destroy wildlife habitat and further threaten rare or endangered species; increase soil salinity, flooding and wildfires; and use great amounts of groundwater. Biological control has a long history of success and safety against weeds in natural areas, both in North America and Hawaii and in other countries. It can be effective, highly specific (will not damage other vegetation), relatively inexpensive, and permanent. Many insect species have been found that damage saltcedar in Asia: 20 of these are being tested by overseas cooperators, 9 species are in quarantine at Temple, TX, and 2 have preliminary clearance for field release. These are the mealybug Trabutina mannipara from Israel, which sucks sap from the twigs, and the leaf beetle Diorhabda elongata from China, Kazakhstan and Turkmenistan, whose larvae and adults feed on the foliage. Final approval for release awaits 1) a Biological Assessment to evaluate the effects of control on the southwestern willow flycatcher and other endangered species and 2) an Environmental Assessment (both in preparation). Biological control will not eradicate saltcedar but is expected to reduce its abundance below the damage threshold and to substantially improve ecosystem health, including that of endangered species. |
