Influence of Irrigation and Wetting Agent on Fungicide Residues in Creeping Bentgrass.

Fungicides (azoxystrobin, propiconazole, pyraclostrobin, and thiophanate-methyl) were applied to field plots of creeping bentgrass established on a sand-based root zone substrate and maintained at a cutting height of 0.34 cm. The wetting agent, a modified alkylated polyol, was applied 24 h prior to fungicide application. Irrigation (0.51 cm) was applied to plots immediately after the fungicide spray. Turf was sampled nine times over 42 days to examine fungicide residues in three components of the turf profile: verdure/thatch, roots, and soil. Residues were extracted from samples and then quantified using a liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) procedure. The experiment was run twice. Wetting agent had little or no effect on fungicide distribution in any of the turf components. Postapplication irrigation had little effect on residues observed in the verdure/thatch component. Significant irrigation treatment effects were observed in root and soil components, but results varied among fungicides and sampling dates. Where significant effects were observed for the irrigation plus wetting agent treatment, results generally mirrored outcomes for irrigation treatment.