Influence of Seedbed Preparation and Seeding Method on Creeping Bentgrass Establishment in Mixed Species Fairway Turf.

Recently developed turfgrass varieties provide golf courses an excellent opportunity to reduce pesticide and water inputs.  However, fairway renovation is challenging due to the large area involved and disruption to play, therefore efficient and rapid renovation practices are required.  Research to optimize fairway renovation practices was initiated on a mature golf course fairway in Wethersfield, CT with a mixed creeping bentgrass (Agrostis stolonifera L.) and annual bluegrass (ABG; Poa annua L.) turf in September 2014.  The study used a split-split plot design with three blocks arranged in a 3 x 4 x 2 factorial.  The main plot was seedbed preparation (none, verticut, or core cultivation), sub-plot was seeder type (no seed, drop, spike, or slit seeder), and sub-sub plot was non-selective herbicide (glyphosate only vs glyphosate + dazomet).  Creeping bentgrass was seeded at a rate of 49 kg ha^-1 except in the no seed plots.  All treatments were completed within 4 days of the initiation of the study.  Dark green color index was used to assess early germination differences among treatments 17 days after seeding (DAS).  All seeders resulted in equivalent germination when the seedbed was prepared with verticutting or core cultivation.  However, drop and spike seeders had lower germination in plots not verticut or core cultivated; whereas slit seeding had good germination regardless of seedbed preparation.  Annual bluegrass contamination was assessed 39 DAS.  Verticutting resulted in the greatest ABG contamination.  Core cultivation had similar or lower ABG contamination as non-cultivated plots.  Core cultivation followed by slit or drop seeding resulted in the least ABG contamination 39 DAS.  The following June, all seeded plots contained approximately 40% ABG regardless of seedbed preparation or seeder type.  Non-selective herbicide treatments had no effect on germination or ABG contamination throughout this study.  Future studies will evaluate these practices during months less favorable for ABG establishment.