2009 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 Lagun 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. 3.Progress Report Studies on the dissipation and efficacy of aquatic herbicides led to their safe and effective use for management of Brazilian egeria in the Sacramento – San Joaquin Delta. Demographics, population spread of invasive waterprimrose species, and the role of an herbivorous insect have helped delineate the problem and may provide some relief. A collaborative effort was begun with University of California to determine the distribution, abundance and impact of weedy Ludwigia in rice to develop alternative rice establishment systems within Sacramento Valley watersheds. Studies were completed to determine optimal timing of approved herbicides for control of giant reed (“Arundo”). 4.Accomplishments 1. Giant Reed Management. Giant reed (“arundo”) is a highly invasive and widespread bamboo-like grass that impairs flood control channels, increases erosion and creates fuel for fires. ARS researchers in Davis, CA demonstrated that use of the herbicide imazapyr in fall had limited effect on growth the subsequent spring. Added water and fertilizer did not facilitate recovery of most native plants. Results will help define management and restoration limitations. 2. Taxonomy of water primrose. Water primrose is really a complex of several species of invasive wetland plants that are spreading rapidly in western states where they out compete native plants. Water primrose may also encourage mosquitoes that are disease vectors. ARS researchers in Davis, California provided a scientific basis for revising taxonomic treatment of the Ludwigia genus. This will facilitate species-specific management strategies and the identification of biological control agents. 3. Biological Control of water primrose. Water primrose spreads in highly sensitive wetland and riparian sites that may not be amenable to use of herbicides. Davis, CA scientists found that some populations in the Central Valley of California and in Southern California supported a leaf-feeding flea beetle, Altica litigata. Results were used in a population model that will estimate the amount of damage that is expected to occur under actual field conditions. Deployment of beetles may help to control water primrose. 4. Invasive Weeds in the San Joaquin River. The San Joaquin River is a critical habitat for salmon and an essential source for potable and irrigation water and requires a major resoration. As background for a major restoration project, ARS scientists in Davis, CA, surveyed this river and found and mapped six species of invasive plants. Initial herbicide efficacy studies were completed on three of the species. An interim report was submitted to the cooperating agency: U.S. Bureau of Reclamation. This information will facilitate multi-agency restoration strategies and programs for the river. 5. New Aquatic Weed Problem. Growth of Western milfoil (Myriophyllum hippuroides) impedes irrigation water delivery. ARS scientists at Davis, CA, found that this plant requires very little light. Because it branches extensively when it reaches the surface it obstructs waterways. Results will help refine field-level studies to determine management options. 6. Potential Biological Control for Brazilian egeria. Brazilian egeria greatly impacts potable and irrigation water sources for over 23 million Californians as it spreads in the Sacramento-San Joaquin Delta. ARS scientists in Davis, CA in collaboration with the USDA-ARS South American Biological Control Laboratory showed that a leaf-mining fly damages the foliage and stems of Egeria and warrants further testing. Facilities within the USDA-ARS Biological Control of Weeds Quarantine at Albany, CA are in the process of being refurbished to handle the rearing and testing of these aquatic insects. The completion of these facilities will help to control the spread if Brazilian egeria. 6.Technology Transfer Number of Other Technology Transfer 3 Review Publications Spencer, D.F., Tan, W., Liow, P., Ksander, G.G., Whitehand, L.C., Weaver, S., Olson, J., Newhouser, M. 2008 Evaluation of Glyphosate for Managing Giant Reed (Arundo donax). Journal of Invasive Plant Science and Management. 1:248-254 Spencer, D.F., Tan, W., Liow, P., Ksander, G.G., Whitehand, L.C. 2009. Evaluation of Late Summer Imazapyr Treatment for Managing Giant Reed (Arundo donax). Journal of Aquatic Plant Management. 47:40-43