Hollow Tine Cultivation and Vertical Cutting Effects on Velvet Bentgrass.

Compared to other species, velvet bentgrass (Agrostis canina L.; VBG) is reputed to accumulate excessive thatch that can create an unacceptable soft or “puffy” playing surface.  The objectives of this field study were to determine the effects of hollow tine cultivation and vertical cutting on playing surface characteristics VBG maintained as a putting green turf.  The trial was initiated in September 2010 on a seven-years-old ‘Greenwich’ VBG turf mowed at 2.8 mm.  The study used a 2 x 2 x 2 factorial arranged in randomized complete block design with four replications.  The factors were September hollow tine coring, April hollow tine coring, and vertical cutting, and.  Coring used applied 12.7-mm i.d. tines and created a lateral and medial hole spacing of 41- and 58-mm, respectively; coring holes were backfilled with medium sand.  Vertical cutting was applied in April using scarification reels and as often as biweekly during the summer using vertical cutting reels.  Sand topdressing was applied biweekly at 0.4 L m^-2.   As expected, turf quality and color was reduced immediately after September and April coring.  Once coring holes had healed, turf quality and color were either not affected or slightly improved by coring.  Coring initially lowered surface hardness initially but increased hardness later in the season. Vertical cutting treatment increased the surface hardness throughout the season. In all three years, vertical cutting produced a subtle but significant reduction in turf quality and color after treatment; improvements in color occurred but less frequently. All cultivation techniques reduced mat depth and the amount of organic matter in the mat layer; however coring, regardless of timing, produced the greatest reduction. Vertical cutting reduced the depth and amount of accumulated organic matter in the mat but did not affect the concentration of organic matter.