Pyraclostrobin was recently found to be highly effective for control of Pythium root dysfunction of creeping bentgrass, caused by Pythium volutum. Experiments were conducted to determine if disease suppression was due to fungicidal effects or physiological effects on the host. Sensitivity in culture was examined using five isolates of Pythium volutum and five concentrations (0, 0.1, 1, 10, and 100 mg L^-1) of pyraclostrobin, azoxystrobin, and mefanoxam. Growth chamber studies were conducted to determine if pyraclostrobin influences foliar and root growth of creeping bentgrass. Treatments consisted of four nitrogen levels (0,100, 200 mg L^-1 applied daily) and seven pyraclostrobin rates (0, 140, 280, 560, 1120, 2240, and 4480 g ha^-1) arranged in a completely random factorial design. Clipping yields and tissue analysis will be collected for the growth chamber study. Culture diameters will be measured to calculate ED₅₀ values to determine fungicide sensitivity of Pythium volutum. Results from both experiments will be presented.