2006 Annual Report 4d.Progress report. This report serves to document research conducted under a specific cooperative agreement between ARS and Colorado State University, Fort Collins. Additional details of research can be found in the report for the parent project, 5366-21000-022-00D, “Small Grains Genetic Resource Management”. Our evaluations for Russian wheat aphid (RWA) resistance began two years ago with a large set of 7290 Iranian landrace selections provided by the National Small Grains Collection (NSGC). By February 2005, we completed evaluation of this set with the new, virulent biotype of RWA (denoted as biotype. 2)identified in Colorado in 2003. By May 2005, we completed the evaluation of a subset of these accessions, chosen based on resistance to biotype 2, using the original North American biotype of RWA (denoted as biotype 1). From these evaluations, a group of 168 accessions were identified that carry high levels of resistance to both biotypes 1 and 2. In 2005-2006, we finalized the progeny testing and isolation of a group of single-plant selections from many of these resistant accessions to develop mapping populations for molecular marker identification. In 2005-2006, we also screened a new group of accessions provided by the NSGC using RWA biotype 2. This set included 5,340 accessions of diverse origin, many from areas where RWA resistance has not been found previously. Evaluations were done as in the past using unreplicated standard greenhouse seedling screening procedures. The vast majority of accessions were scored as susceptible (>3 for chlorosis and flat for leaf rolling score).