Start Date: Nov 01, 2007
End Date: Oct 31, 2011
With the aid of cooperators in ND, SD, KS, and TX, I will collect rust races from both cultivated and wild sunflower and will determine the races to document their distribution and changes over time. Rust race identification is accomplished in greenhouse tests in which seedlings of differential lines are inoculated and rated two weeks later. This objective is planned to be done for three consecutive years to be able to monitor changes in geographic distribution, as well as changes in rust races. Once the predominant rust races has been determined, we will evaluate commercial oilseed and confection hybrids in USDA greenhouse tests. Additionally, we will evaluate both known rust-resistant USDA releases and the most recent USDA releases. If we encounter a highly virulent rust race for which there is no resistance in released USDA germplasm or commercial hybrids, we propose to begin evaluation of the USDA cultivated sunflower "core collection." Failing to find resistance in this group, we would expand our search to annual wild Helianthus species, of which there are currently 345 accessions of 19 taxa available from the USDA-NCR Plant Introduction Station.