Crown rust, caused by the fungus Puccinia coronata, is a severe disease negatively impacting seed quality and yield in oat (Avena sativa).  Host genetic resistance is the primary means for controlling this disease.  The most extensive oat map contains nearly 2,500 genetic markers, many of which are restriction and amplified fragment length polymorphic (RFLP or AFLP) markers.  However, the use of more abundant single nucleotide polymorphic (SNP) markers combined with diversity arrays (DArT) technology would be more advantageous for marker assisted breeding (MAB) and genome wide selection (GWS) applications due to the availability of high density genotyping technologies.  The purpose of using this technology is to improve the competitiveness of oat by producing varieties with durable resistance to crown rust and desirable traits that will benefit oat growers in the southern U.S.  Panels of winter and spring oat were evaluated for resistance to crown rust in two field environments during a two-year study.  Plants representing 702 elite lines of oat were phenotyped and genotyped to map loci for crown rust resistance using association mapping approach.  The results are expected to increase knowledge of the genetic diversity of the oat germplasm, yield comprehensive genotyping and phenotyping information for North American oat breeding programs, and to promote further use of GWS and MAB for key traits regarding disease resistance in oat.