Assessment of Management Practices to Alleviate Excessive Thatch On a Mixed Species Golf Green.

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Numerous issues on golf course greens result from the formation of excess thatch levels, including reduced water infiltration, increased pest and disease damage and reduced root growth.  This study was undertaken to determine the effects of various management practices on the remediation of thatch on a 15-year-old mixed-species golf green grown on a USGA-specification rootzone.  Treatments include core aeration with either 6.35 mm or 15.8 mm tines, solid tine aeration with 6.35 mm tines, vertical mowing at 0.5 cm, 1 cm or 2 cm depth, and combinations of the various treatments. Weekly topdressing was also studied as a split plot for each treatment combination. Thatch levels were measured in 19 mm soil cores at two separate points using a ruler.  Percent organic matter was measured by loss on ignition.  After two years of treatments, thatch levels were not reduced by any of the treatments, although percent organic matter in the top 2.5 cm of a 5 cm core was significantly reduced as a result of core aerification and the two deepest vertical mowing treatments. In addition, water infiltration was improved with the 15.8 mm core aerification treatment. Weekly topdressing significantly increased thatch depth but reduced percent organic matter, suggesting this method dilutes the thatch rather than reducing it.  The study will continue for two more years, but results indicate that cultivation practices can improve soil conditions and reduce percent organic matter in the top 2.5 cm of soil.