2007 Annual Report 1a.Objectives (from AD-416) To develop hard winter wheats with resistance to nascent races of stripe rust in the Great Plains. 1b.Approach (from AD-416) Wheat germplasm of diverse and world-wide origin will be exposed to nascent races of stripe rust. Seed of resistant lines will be increased, under quarantine, and distributed to wheat breeding programs throughout the U.S. 3.Progress Report This report documents research conducted under a Specific Cooperative Agreement between ARS and Oklahoma State University. Additional details of research can be found in the report for the in-house associated project 5440-21000-025-00D, Genetic Improvement and Evaluation of Hard Winter and Spring Wheats. During the 2007 crop cycle, the germplasm development team of the Wheat Improvement Team (WIT) at OSU made more than 150 single and three-way crosses for stripe rust resistance, plus more than 80 crosses involving primary synthetics. This represents approximately 25% of the total crosses made in the program. Most of the single and three-way crosses involved different spring wheat lines from CIMMYT/Mexico that have multiple minor genes or durable stripe rust resistance. The F2 populations from the crosses made during the 2006 crop season will be evaluated in the regional disease nursery in 2008 in south Texas. Stripe rust was not prevalent in this nursery during the 2007 cycle, but F2 populations of crosses that were previously made for stripe rust resistance were selected for leaf rust resistance, and the most promising F3 populations will be shared this fall (2007) with interested wheat breeders. Seven different international spring wheat nurseries from CIMMYT, consisting of 914 advanced lines, and 448 primary synthetics from CIMMYT were grown in the south Texas disease nursery in the 2007 crop cycle (Table 1). As indicated above, very little stripe rust was present in 2007. Numerous selections for leaf rust resistance and agronomic type were made in each nursery and among the primary synthetics, and these selections (more than 400 advanced lines and synthetics) will be sent to interested breeders during the summer of 2007. As of July 15, 2007, eighteen wheat breeders have requested all or a portion of the selected materials. Additionally, seven new international nurseries from CIMMYT were cleared through quarantine procedures during the 2007 season. These nurseries contain 1221 advanced spring wheat lines and most of them have stripe rust resistance in Mexico. Also, many newly selected advanced lines with “multiple minor genes (MGR) or durable resistance” to stripe rust are included in this germplasm. These materials will be evaluated for stripe rust resistance and agronomic type in the south Texas disease nursery in 2008. Sets of each of these nurseries are being prepared and will be sent to interested wheat breeders in the summer of 2007. To date, 22 wheat breeders have requested selected materials from these international nurseries from CIMMYT. For breeders who do not want to evaluate large numbers of materials, they have the option of waiting and receiving a set of the selected materials from the south Texas nursery in 2008. Progress is monitored via attendance at the annual Hard Winter Wheat Breeders Field Day, and via emailed progress reports from cooperators.