2007 Annual Report 1a.Objectives (from AD-416) Develop new methodologies for completely controlling (eradicating) vegetative and reproductive and dispersal capacity of Hydrilla verticillata in flowing and standing-water sites. Determine efficacy and new uses for existing and new systemic and contact herbicides. Examine potential for other non-chemical eradication methods, such as physical removal, ultrasonic exposures and applied electric fields. 1b.Approach (from AD-416) Replicated laboratory and outdoor culture treatments will be made to established H. verticillata and mature propagules (tubers and turions) using penoxsulam, carfentrazone and various forms of chlorine. Exposures will include in-water and simulated “drawdown” (exposed sediment) applications where appropriate. Assessment of on-going eradication methods at Clear Lake, CA will be made using bioassays coupled with analysis of herbicide residues in sediment cores. Exploratory examination will be made to determine effects of ultrasonic energy and low power, applied electrical fields on propagule viability. Documents Reimbursable with CA Department of Food and Agriculture (CDFA) 3.Progress Report This report serves to document research conducted under a Reimbursable Agreement between ARS and the California Department of Food and Agriculture. Additional details of this Research can be found in the report for the parent project 5325-22000-019-00D, Biologically-Based Integrated Management of Invasive Aquatic & Riparian Weeds. Culture systems and cultures of hydrilla were established and efficacy testing of penoxsulam and imazamox was begun. A replicated outdoor (natural light) culture systems was constructed to conduct efficacy testing. The 80-container system allows for 4 to 6 replicate treatments in 90 liter containers that are individually equipped with aeration and flow-through input. Evaluation of two herbicides for control of hydrilla and Egeria densa is underway.