2006 Annual Report 4d.Progress report. This report serves to document research conducted under a specific cooperative agreement between ARS and the University of California. Additional details of research can be found in the report for the parent project, 5366-21000-022-00D, “Small Grains Genetic Resource Management”. In the 2005-06 crop cycle evaluation of Iranian and other genetic resources was continued. Emphasis was placed on search for barley yellow dwarf virus resistance, but this was not successful, in spite of repeated plantings of aphid traps and inoculation of the traps with greenhouse grown aphids. The early spring season was unusually wet with rains throughout the month of April. Both fall and spring plantings of evaluation materials were made in replicated trials, some 10,000 plots were planted. Even though the BYD trials were unsuccessful, the season was favorable for stripe rust development and evaluation for other traits. In 2005 we scored growth habit of Iranian landrace successions after spring planting. The winter and spring types were separated for fall and spring planting for 2005-06 cycle. Surprisingly, when the spring types were planted in the spring 2006, 23.5% of them had winter growth habit. Among the spring types, 63.0% were typical early-heading types and 10.9% were late-heading spring types. The 2005 planting was made in March while the 2006 planting was made at the end of April, suggesting that in 2005 some of the winter types vernalized and were scored as spring types, while the later planting in 2006 did not provide vernalizing temperatures. These results suggest that the so-called facultative types were sensitive to weak vernalization temperatures. Further research is needed to clarify these interesting results. The late spring planting of Iranian landraces did not develop BYD symptoms and post-emergence irrigation was not applied. This resulted in considerable heat and moisture stress on the plantings. Some of the spring types, especially those heading early, showed exceptional vigor and 97 accessions were noted as candidates having environmental stress tolerance. The fall-planted Iranian winter type accessions showed exceptionally good stripe rust symptoms. In earlier years we had noted a high frequency of resistant types in the Iranian wheat collection. Beginning April 22, 622 accessions and check varieties were scored 5 times to establish disease development patterns. The last scoring was done on May 22. The accessions showed a wide range of disease expression. Results from the final scoring showed the following frequencies: Highly Resistant, 0% stripe rust, 181 accessions, 27.7%; Resistant, 1-5%, 57, 8.7%; Moderately Resistant, 10-20%, 75, 11.5%; Moderately Susceptible, 30-50%, 52, 8.0%; Susceptible, 60-70%, 48, 7.3%; Highly Susceptible, 100%, 241, 6.8%. This is a very high frequency of resistant types, with various levels of resistance, among a collection of landraces that surely offers good sources of resistance for plant breeders.