2007 Annual Report 1a.Objectives (from AD-416) 1) Improve our biological understanding and enhance our ability to manage important invasive weeds in western aquatic and riparian ecosystems.. 2)Develop integrated vegetation management strategies to restore ecological structure and function to western aquatic and riparian ecosystems.. 3) Determine the most ecologically sound and cost effective methods for managing aquatic and riparian weeds using herbicides and/or natural products.. 4)Develop rapid response strategies and methods for aquatic plant infestations that pose serious economic and environmental threats. 1b.Approach (from AD-416) 1) A demographic study will determine how temporal and spatial variation in factors affecting Uruguayan water primrose contribute to overall population dynamics and improved management and restoration at Laguna de Santa Rosa. . 2)Egeria Carbon Hydrogen Nitrogen (CHN) and associated insect communities will be determined monthly at invaded/ non-invaded sites at in the Sacramento/San Joaquin Delta using presence/absence and hydroacoustical and videographic methods. . 3)Eurasian watermilfoil will be sampled (weekly to monthly) in the Truckee and Fall Rivers along streamflow gradients. . 4)Effects of simulated herbivory on giant reed and effects on root growth (abundance, life span) will be quantified from images recorded with a video camera system within the minirhizotrons at weekly intervals. Success of active (planting desirable species) versus passive (recruitment from resident propagules) re-vegetation will be assessed in giant reed managed sites. 5)Effects of native and non-native submersed plants on rhizosphere microflora will be assessed in replicated mesocosms and natural populations. . 6)Replicated applications of fluridone, copper will be made in water and with penoxsulam, or acetic acid to canals and canal sediment. . 7)Methods to eradicate curlyleaf pondweed will be evaluated in indoor and outdoor tanks using diquat, endothall, and penoxsulam under short and long-day conditions. 4.Accomplishments Mapping Aquatic Weeds in Lake Tahoe: Lake Tahoe (CA/NV) is infested with at least two submersed, exotic plants that impair ecological functions and interfere with recreational and commercial activities. Scientists in the Exotic and Invasive Weeds Research Unit, Albany, CA completed lake-wide surveillance and generated georeferenced maps showing the extent and locations of Eurasian watermilfoil and Curlyleaf pondweed. Researchers found that populations of these invasive plants are continuing to spread. This prompted a multi-agency workshop that has led to the development of long-range management planning activities for invasive species at Lake Tahoe. (National Program 304, Component:Weed Science, Problem Statement:Biological Control of Weeds.) Cord Grass Control: Smooth cordgrass (Spartina alterniflora) has invaded San Francisco Bay where it has excluded native cordgrass (Spartina foliosa), or has hybridized with the native cordgrass. Scientists in the Exotic and Invasive Weeds Research Unit, Albany, CA completed a two-season assessment of the impacts of the herbicide use on native plants in five locations around the bay. It was found that while there was some initial negative impact of the herbicide some sites recovery was generally observed a year after the first applications of herbicide. This information will help provide a “bench mark” for further monitoring of the Spartina Control Program. (National Program 304, Component:Weed Science, Problem Statement:Biological Control of Weeds.) Rapid Response to Invasive Weeds: Rapid responses to new invasive aquatic species reduces the cost and impacts of these organisms. Scientists in the Exotic and Invasive Weeds Research Unit, Albany, CA organized and conducted a workshop and “pest-alarm” exercise to identify the pathways, site-susceptibility and potential containment and control options for two species of invasive aquatic plants that are not presently in western states (water chestnut and Lagarosiphon major. The workshop provided a foundation for development of early detection and rapid response actions for the two target invasive aquatic weeds, and is being used by the California Dept. of Food and Agriculture for assessment of threats to ecosystems and irrigated agriculture. (National Program 304, Component:Weed Science, Problem Statement:Biological Control of Weeds.) Arundo donax (Giant Reed) Growth and Spread: Arundo donax (giant reed) spreads invasively by producing new shoots (ramets) from rhizomes. ARS Researchers in Albany, CA, performed two separate experiments that showed that no ramets emerged from rhizome sections at temperatures of 7 or 8 C, but ramets emerged at 14, 16, and 20 C. These results, in combination with ramet emergence data from plants grown outdoors at Davis, California were used to predict ramet emergence. This is an important step in developing integrated management plans for this species.(National Program 304, Component:Weed Science, Problem Statement:Biological Control of Weeds.) Arundo donax (Giant Reed) Leaf Growth and Development: Scientists in the Exotic and Invasive Weeds Research Unit, Albany, CA measured C content, N content, C:N ratio, and chlorophyll index (SPAD 502 reading) for 768 leaves from Arundo donax (giant reed) collected over a five year period at several locations in California, Nevada, and Texas. Leaf N was more variable than leaf C, and thus we developed a linear regression equation for estimating Arundo donax leaf N from the leaf chlorophyll index (SPAD reading). When applied to two independent data sets, the equation (leaf N content % = -0.63 + 0.08 x SPAD) produced realistic estimates that can be used in conjunction with the handheld SPAD 502 meter, for estimating Arundo donax leaf quality. (National Program 304, Component:Weed Science, Problem Statement:Biological Control of Weeds.) Systematic Assessment of Invasive Waterprimrose: Ludwigia species (waterprimrose) have aggressively invaded canals and aquatic ecosystems, and threaten food control systems and federal water project deliveries. Scientists in Albany, CA completed an extensive cytological analysis that differentiated three chromosomal races (n = 8, 24, 40) and 3 exotic species of Ludwigia were differentiated. In collaboration with ARS-SABCL, we sampled Ludwigia populations in US west coast states, Argentina, and Uruguay for molecular evaluation to support biological control research. Research will increase our knowledge and understanding of systematic assessment of invasive waterprimrose. ( National Program 304, Component:Weed Science, Problem Statement:Biological Control of Weeds.) Invasive Growth of Waterprimrose: Ludwigia spp. respond to different environmental conditions (such as water levels) by changing its growth form. Scientists in Albany, CA, conducted experiments to understand Ludwigia growth responses to hydrology, nutrient and light regimes and better understand mechanisms influencing weed establishment, colonization and spread. Experimental research to understand recruitment of undesirable species from seed banks, and relationships between seed banks and standing flood plain vegetation are underway to help manage exotic species, restore native communities, and better understand resilience of flood plain plant communities. (National Program 304, Component:Weed Science, Problem Statement:Biological Control of Weeds.) 5.Significant Activities that Support Special Target Populations None 6.Technology Transfer Number of non-peer reviewed presentations and proceedings 13 Number of newspaper articles and other presentations for non-science audiences 3 Review Publications Spencer, D.F., Sher, A., Thornby, D., Ksander, G.G. 2007. Non-destructive assessment of arundo donax (poaceae) leaf quality. Journal of Freshwater Ecology. 22(2):277-285. Grewell, B.J., Callaway, J.C., Ferren, W.R. 2007. Estuarine wetlands. In: Barbour, M.G., Keeler-Wolf, T., Schoenherr, A. A., editors. Terrestrial Vegetation of California. 3rd edition. Berkeley, California: University of California Press. p.124-154. Fiedler, P.L., Keever, M.E., Grewell, B.J., Partridge, D.J. 2007. Rare plants in the golden gate estuary: scale and understanding. Australian Journal of Botany.55:206-220. Spencer, D.F., Lembi, C., Blank, R.R. 2006. Spatial and temporal variation in the composition and biomass of algae present in California rice fields. Journal of Freshwater Ecology. 21:649-656. Spencer, D.F., Ksander, G.G. 2006. Estimating arundo donax ramet recruitment using degree-day based equations. Aquatic Botany. 85:282-288.