BIOLOGICAL CONTROL OF SALTCEDAR (TAMARIX: TAMARICACEAE) IN THE UNITED STATES COULD BE EXTENDED TO INCLUDE CONTROL IN NORTHERN MEXICO

Authors: Deloach Jr, Culver; Carruthers, Raymond; RODRIGUEZ-DEL-BOSQUE, LUIS - INSTITUTO NACIONAL FOREST

Submitted to: Proceedings of National Congress of Biological Control
Publication Type: Proceedings
Publication Acceptance Date: 11/14/2003
Publication Date: 1/10/2004
Citation: Deloach, C.J., Carruthers, R.I., Rodriguez-del-Bosque, L.A. 2003. Biological control of saltcedar (Tamarix: Tamaricaceae) in the United States could be extended to include control in northern Mexico. In: Memoirs of the XXVI Congresso Nacional de Control Biologico, November 3-8, 2003, Guadalajara, Jalisco, Mexico. p. 228-230.

Interpretive Summary: Saltcedars, small shrubs or trees in the plant genus Tamarix were introduced from Asia into the United States in the 1800s but now have escaped cultivation and have invaded the highly valuable riverbottoms and lakeshores in the west. They cause great damage by using great quantities of scarce ground water and reducing stream flow needed for agriculture and municipalities, displacing native plants with dense thickets of low value saltcedar thickets, severely damaging wildlife habitat, including that of many rare and endangered species, and increasing soil salinity and wildfires. The saltcedar leaf beetle from Asia was released in Colorado, Wyoming, Utah and Nevada in May 2001 to feed on and control this weed. The beetle is increasing rapidly and now, after 3 years, has defoliated from 15 to 500 acres of saltcedar at 5 release sites in those states and the damage is rapidly increasing each year. Four other forms of this same beetle, from further south in Asia and the Mediterranean area were tested, also found to be safe, and in 2003 two of these types were released at 6 sites in Texas, New Mexico and California. Successful biological control of saltcedar is expected to increase the water in western rivers that would be available for cities and irrigated agriculture, to reduce saltcedar stands and restore native plant and wildlife communities, to reduce wildfires and lower soil salinity levels, and to improve hunting, fishing, camping and the enjoyment of natural areas.

Technical Abstract: Four species of saltcedars (Tamarix spp.) and their hybrids, small trees or shrubs native in the Old World, have invaded riparian areas of the western United States and northern Mexico. Here, they are producing enormous environmental and economic losses by using great quantities of scarce groundwater and stream flow and by displacing native plant communities, degrading wildlife habitat, further threatening some 40 species rare and endangered species, increasing soil salinity and wildfires and damaging parks and wildland recreational values. A leaf beetle, Diorhabda elongata, introduced from Asia was tested by USDA/APHIS in quarantine at Temple, TX and Albany, CA, and found safe to non-target plants. It was released in the field at 10 sites in 6 western states in May 2001. After 3 growing seasons it has completely defoliated from 15 to 500 acres of saltcedar at 5 of these sites north of the 38th parallel, and the damage is increasing dramatically (ca. 30 fold) each year. Four additional biotypes of this beetle from more southern regions of Asia and the Mediterranean area have been tested and appear to be adapted to southern areas including northern Mexico. In 2003, two of these biotypes were released at 6 sites south of the 37th parallel in Texas, New Mexico and California.