2005 Annual Report 4d.Progress report. 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”. We began our evaluations for Russian wheat aphid (RWA) resistance using a collection of Iranian landrace accessions provided by the National Small Grains Collection (NSGC). Due to the large numbers of accessions provided, and the relatively modest capabilities of our screening system, we divided our Russian wheat aphid (RWA) biotype 2 resistance screening for of the total collection (7,290 accessions) among four different evaluation sets. For each screening set, accessions were screened in standard greenhouse seedling screening experiments. Accessions showing a leaf chlorosis score ' 3 and a leaf rolling score of "Flat" were deemed to be resistant. Based on these evaluations, a group of 322 accessions showing resistance against RWA biotype 2 were evaluated for resistance to the original North American RWA biotype, denoted as biotype 1. These evaluations were conducted in a controlled-environment growth room to minimize potential risk of contamination of the two colonies that might compromise the evaluations. Due to space limitations in our growth room, we chose to evaluate only those accessions with the highest levels of resistance in the biotype 2 evaluations (e.g., leaf chlorosis score '2, leaf rolling score of "Flat"). To date a total of 191 accessions show resistance to both biotypes.