2006 Annual Report 4d.Progress report. This report serves to document research that will be conducted under a non-funded cooperative agreement (between ARS and Bayer Crop Science International. Additional details of research can be found in the report of the parent CRIS 6657-21000-005-00D, Enhancing the Sustainability of Cotton Production in the Southeast USA. The objective of this cooperative research project will be to determine if host plant tolerance to hardlock is controlled by a genetic system consisting of one or a few genes or by a genetic system consisting of numerous genes that are inherited in a quantitative way.