2006 Annual Report 4d.Progress report. This report serves to document research conducted under a Specific Cooperative Agreement between ARS and Texas A&M University. Additional details of research can be found in the report for the parent CRIS 6202-22000-021-00D Pathogen Biology, Genetics, Population Dynamics, Spread, and Relationship with Host and Vectors. The goal of this project is to identify better procedures or protocols to manage ergot disease of sorghum. In FY 2006, 60 sorghum hybrids were evaluated in Weslaco, Texas, following inoculation with ergot. There was nearly 100% incidence of ergot in all but two of the hybrids (AgriPro WAC690 and ATx631*RTx436), although ergot severity varied among the different hybrids tested, from a few infected florets per head to more than 76% of the head infected. Severity tended to be higher among hybrids that flowered early and may be associated with impaired pollen development because of cold weather. A low severity of ergot in some of the hybrids could reflect a greater degree of cold temperature tolerance. Work by this project is important in understanding environmental conditions that either promote or reduce ergot infection, and will aid sorghum producers in better managing ergot disease to minimize its negative impact on sorghum production.