Several Pythium species causing leak on potato and seed rot of crops found in rotation with potatoes are managed by the systemic fungicide metalaxyl (Ridomil, Apron or Allegiance).  Soil samples from 312 fields cropped to potatoes in Idaho (140), Oregon (59), and Washington (113) were assessed for the presence of metalaxyl-resistant (MR) isolates of Pythium.  Altogether, 1.4%, 42.4%, and 32.7% of the fields from these states, respectively, were positive for MR Pythium.  The percentage of MR Pythium isolates to metalaxyl-sensitive isolates found in a field ranged from 0.9 to 92.5%.  Growers were informed of problematic fields impacting their disease management programs and alternative products are being investigated that will manage MR Pythium.