Phytophthora root rot (caused by Phytophthora sojae) can be a destructive disease of soybean in years in which rainfall and wet soils are abundant. Management of this disease is accomplished primarily through the use of resistant varieties that utilize either single resistant genes (known as Rps genes) or partial resistance (sometimes referred to as “field resistance” or “tolerance”). The use of Rps genes over time has allowed for the selection of races of P. sojae that can overcome specific Rps genes, rendering these resistant genes ineffective. Understanding the diversity of P. sojae races in Kentucky can help soybean farmers make better choices when selecting varieties, and can help soybean...