Glyphosate Application Timing Affects Tall Fescue Conversion to ‘Sharp's Improved II ' Buffalograss.

Buffalograss [Buchloe dactyloides (Nutt) Engelm.] is a native warm season turfgrass that requires minimal inputs for acceptable quality increasing popularity in the transition zone. Proper glyphosate application timing is vital to reduce green cover loss for conversion from tall fescue (Lolium arundinacea).  Limited information exists on pre- and post-seeding glyphosate application timings. The objective of this study was to determine the optimal glyphosate application timings for conversion of tall fescue to buffalograss.  Field studies were initiated on 8 June 2015 and 2016 at the Rocky Ford Turfgrass Research Center in Manhattan, KS. Study design was a randomized complete block, with a 5 × 5 factorial treatment structure, with four replications.  Factors were glyphosate application timings; weeks before seeding (WBS) and days after seeding (DAS). WBS treatments included 4, 3, 2, 1 WBS, and a non-treated. DAS treatments included 0, 2, 4, and 7 DAS, and a non-treated. Treatments were applied to 1.2 x 1.2 m plots.  Glyphosate applications were applied at 2.2 kg ha^-1.  ‘Sharp’s Improved II’ buffalograss was seeded on 7 July 2015 and 2016 at 195 kg ha^-1. Buffalograss visual cover (0-100%), tall fescue visual cover (0-100%), buffalograss color (1-9), buffalograss quality (1-9), digital image analysis (0-100% green cover), and weed cover (0-100%) were collected weekly for 18 weeks after initiation. Analysis of variance was preformed using SAS (SAS Institute, Inc., Cary, NC), and means were separated according to Fisher’s Protected LSD (P < 0.05).  Slower buffalograss establishment was observed for all treatments receiving 7 DAS glyphosate applications and treatments receiving no glyphosate applications. All treatments provided acceptable establishment (90% buffalograss cover) by 70 DAS except treatments receiving no glyphosate applications (<5% buffalograss cover).