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United States Department of Agriculture

Agricultural Research Service

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Project Number: 6204-22000-022-00-D
Project Type: In-House Appropriated

Start Date: Oct 1, 2010
End Date: Jan 12, 2012

The long-term objective of this project is to reduce the impact of invasive weeds in the Lower Rio Grande Basin (LRGB) and other southwestern watersheds. Over the next 5 years we will focus on the following objectives: Objective 1: Import, culture, and conduct biological studies and host range tests on candidate natural enemies for Arundo donax. Develop mass rearing and mass release methods for permitted agents. Evaluate impacts of biological control agents in the Rio Grande Basin and other watersheds of the Southwestern U.S. Subobjective 1A. Import and evaluate candidate natural enemies of Arundo donax in quarantine for safety and efficacy. Subobjective 1B. Evaluate (1) methods for mass release of biological control agents of Arundo donax and (2) related impacts of introduced natural enemies in the field. Objective 2: Evaluate impacts of tamarisk leaf beetles for biological control of Tamarix spp. saltcedars in the LRGB and in coastal Texas, and develop new agents. Subobjective 2A. Release and evaluate tamarisk leaf beetles (Diorhabda spp.) at sites in the LRGB that contain mainly T. ramosissima and T. chinensis saltcedar, and assess effects on exotic athel trees, Mexican Frankenia species, and native vegetation. Subobjective 2B. Release and evaluate Diorhabda tamarisk beetles for biological control of Tamarix canariensis/T. gallica at coastal sites. Subobjective 2C. Discover and evaluate new agents from the western Mediterranean for biological control of saltcedar. Objective 3: Begin initial foreign exploration and feasibility studies for biological control of guineagrass and elephant ear. Subobjective 3A. Begin initial foreign exploration and feasibility studies for biological control of guineagrass, and determine the distribution and impact of this plant in the LRGB and other watersheds. Subobjective 3B. Begin initial foreign exploration and feasibility studies for biological control of elephant ear, and determine the distribution of this plant in the LRGB and other southwestern watersheds.

Giant reed, saltcedar, guineagrass, and elephant ear are invasive, non-native weeds that compete for scarce water resources in arid regions facing critical water shortages for agricultural, municipal, and environmental uses and, in addition, cause many other ecological and economic problems in the Lower Rio Grande Basin (LRGB) of Texas and northern Mexico. The LRGB is the largest watershed in North America, and biological control of these important riparian and terrestrial weeds has not been developed. This project will discover, evaluate, and implement multiple biological control agents to control giant reed along the Rio Grande and throughout the LRGB. Remote sensing and land-based field studies will be used to measure the impact of a biological control program on vegetation change and water use. The project will also evaluate the field efficacy of tamarisk leaf beetles to control saltcedar in south Texas rangelands and coastal grasslands, areas not previously subjected to biological control, as well as evaluate potential non-target effects on related native plants that are relevant to future biological control of saltcedar in Mexico. In addition, the feasibility for biological control of guineagrass, an invasive, fire-promoting weed in LRGB agriculture and rangelands, and of elephant ear, a large, leafy plant that invades the edges of rivers and reservoirs, will be determined by compiling information on the distribution, impact, and uses of these weeds along with preliminary information from the literature and initial explorations for potential biological control agents. This research will produce environmental and economic benefits by conserving water resources associated with giant reed and saltcedar infestations of the LRGB, and by defining new weed targets to achieve further water savings in the future.

Last Modified: 2/23/2016
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