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United States Department of Agriculture

Agricultural Research Service

Research Project: Aquatic and Riparian Weed Management to Protect U.S. Water Resources in the Far West United States

Location: Exotic and Invasive Weeds Research

Title: Spongeplant Spreading in the Delta

Authors
item Anderson, Lars
item Akers, Pat -

Submitted to: California Invasive Plant Council
Publication Type: Popular Publication
Publication Acceptance Date: May 6, 2011
Publication Date: May 22, 2011
Citation: Anderson, L.W., Akers, P. 2011. Spongeplant Spreading in the Delta. California Invasive Plant Council. Cal-IPC News-Spring 2011, Vol. 19, No. 1; p.4-5.

Interpretive Summary: The Sacramento- San Joaquin Delta in California (Delta) is a vital resource for water used for irrigation, domestic consumption (potable water) for over 20 million Californians, and it is critically important habitat for many important native fish, wildlife, and native plants. These ecosystems services have been impacted by several introduced, exotic plants such as water hyacinth and Brazilian waterweed. Management of these two species alone cost over $5million annually. A new exotic floating plant, South American spongeplant (Limnobium laevigatum) was found in tributaries to the Delta and in the Delta in 2007. Its growth rate and dispersal capacity of suggest that it may interfere with ecosystem services in the Delta as much as water hyacinth can. Rapid response actions by the California Department of Food and Agriculture and USDA- ARS (EIWR-Davis) include physical removal, identifying effective herbicides that can be used safely, and investigating the potential for biological control.

Technical Abstract: Invasive, exotic aquatic plants impact a range of important economic and ecological functions in the Sacramento-San Joaquin Delta of California, and the state now spends over $5 million to control water hyacinth and Brazilian waterweed. In 2007, a new exotic floating plant South American Spongeplant (Limnobium laevigatum) was discovered in the San Joaquin River, which flows into the Delta. This non-native plant has also been found in small colonies in the Delta since 2007. It had been first found in a small impoundment in California in 2003, but its rapid clonal growth, reproductive rate, coupled with small, floating seedlings suggest a very high dispersal potential of this species in the Delta. This new pest poses a serious threat to the navigation in Delta waterways, may impede water delivery to 20 million Californians, and may further stress endangered fish species in the Delta. USDA-ARS and California Department of Agriculture are taking rapid response actions, including physical removal of small colonies, and identifying effective herbicides. Research to develop long-term management using biological control is planned by USDA-ARS through collaborations with its South American Biological Control Laboratory in Buenos Aires, Argentina.

Last Modified: 8/27/2014