The soybean cyst nematode (SCN, Heterodera glycines) is the most damaging pathogen of soybean and is widespread in Minnesota and most soybean-growing regions of the world. As a species, SCN contains significant variation in virulence (ability to reproduce on different soybean lines) and morphology. For this project we propose to study the phenotypic and genotypic diversity of SCN in Minnesota. Specifically, we will phenotype 185 inbred lines of cyst nematodes randomly selected from Minnesota soybean fields for their virulence phenotypes on the SCN-resistant germplasm lines PI 88788, Peking (PI 548402), Pickett (PI 548988), PI 567516C, PI 438489B, and PI 90763. These germplasm lines contain diverse SCN resistance genes. We will also study variations in SCN morphology and conduct whole-genome sequencing on these inbred SCN lines. The knowledge of SCN phenotypic and genotypic diversity will be highly useful for strategically breeding soybean cultivars resistant to soybean cyst nematode with the most effective sources of resistance. This project will advance technology to manage the most destructive pest of soybean and maintain the crop’s productivity in Minnesota.