Influence of Management Practices on Distribution of Fungicides in Golf Course Turf.

Fungicide application is a common practice for controlling root diseases that affect golf course turf. Post application irrigation and wetting agents are often suggested to facilitate downward movement of fungicides. However, understanding of how irrigation and wetting agents influence fungicide distribution in the turf profile is not clear in existing literature. The objective of this research was to investigate the influence of a wetting agent and post-application irrigation on distribution of modern fungicides in a sand-based creeping bentgrass putting green. Fungicides used in two distinct experimental runs in field plots included azoxystrobin, fluxapyroxad, propiconazole, and pyraclostrobin. Irrigation, wetting agent, and irrigation + wetting agent treatment effects were compared with a fungicide-only treatment. Turf was sampled at 0, 3, 7, 10, 14, 21, and 28 d after fungicide treatment. Core samples were separated into three components--verdure thatch, sand at 2-5 cm depth, and sand at 5-8 cm depth. Fungicide was extracted from each turf component and analyzed thereafter using liquid chromatography-triple quadrupole mass spectroscopy. Results showed that the majority of fungicide was captured by verdure thatch, and that fungicide concentration in verdure thatch was 1-2 orders of magnitude higher compared to other turf components. Further, in almost every case, there was no measurable effect on fungicides distribution of treatments: irrigation, wetting agent, or the combination. Research results can help improve understanding of fungicide distribution in turf and provide scientific context for recommendations regarding root disease control in golf course turf.