"Although there have been instances in which low-level presence of regulated materials has resulted in market disruptions (e.g., Starlink corn, LL601 and LL604 rice), there is no evidence of significant market disruption associated with the commercialization of deregulated biotech traits in the United States. Concurrent with increased U.S. farmer adoption of biotech traits in corn, soybean, and cotton there have been increases in U.S. grain/fiber export (USDA-FAS 2007) and organic production (USDA-NASS 2007a, b, c). Although only 3 to 5% of the U.S. alfalfa hay production is sold to GE-sensitive markets (Putnam 2006), production for these markets has significant economic importance in specific regions of the United States. Approximately 33% of U.S. alfalfa seed production is exported, primarily to GE-sensitive markets. A thorough understanding of gene flow in alfalfa is critical to establishing stewardship programs that enable coexistence between alfalfa growers producing GE alfalfa hay or seed and growers producing these products for GE-sensitive markets. Understanding the relative importance of gene flow between and within feral plants, hay, and seed production fields helps to identify key biological, agricultural, and environmental barriers to gene flow and to formulate logical mitigation strategies for managing the AP of GE traits in non-GE alfalfa seed and hay. Synchrony in flowering, presence of pollinators, isolation distance, and relative abundance of pollen between pollen source and pollen recipient plants are typical biological barriers, most of which are amenable to management in hay and/or seed production systems. In general, it seems that NAFA Best Management Practices in hay and certified alfalfa seed production, coupled with the pollinator-specific isolation guidelines outlined in the NAFA Best Management Practices document, are adequate for managing AP to tolerance levels appropriate for most markets. These types of management practices are employed successfully by producers of certified seed in most crops, including alfalfa, to ensure genetic purity of seed stocks. Increased isolation distances in seed production--including production in non-GE seed production zones--use of border areas, crop rotation, use of certified seed, careful selection of the introduced pollinator, and routine elimination of neighboring feral alfalfa plants are tools that can be applied to decrease further the risk of gene flow in the production of seed for GE-sensitive markets."--Summary.