Measuring Canopy Anomaly Influence on Golf Putt Kinematics: Does Annual Bluegrass Influence Ball Roll Behavior?

Abstract

Weedy annual bluegrass (Poa annua L.) has long been presumed to affect ball roll. However, no peer‐reviewed research has evaluated the impact of annual bluegrass or other putting green surface anomalies on ball roll direction. Results to date suggest that several sources of error must be controlled before influence of annual bluegrass on ball directional imprecision can be measured. By using a mechanical putter to avoid directional errors associated with simulated putt devices, selecting balanced golf balls, eliminating legacy effects of repeated ball rolls, and scoring ball direction 30 cm before terminal motion, we were able to limit ball directional imprecision to 4.9 mm m−1 on creeping bentgrass (Agrostis stolonifera L.) greens. When a mechanical putter was used to putt balls across 200 transects spanning eight greens at two Virginia golf courses, directional imprecision of ball roll increased from 4.9 mm m−1 on visibly pure creeping bentgrass to 13 mm m−1 when the balls traversed a small patch of annual bluegrass. Directional imprecision of balls rolled by the Greenstester was independent of annual bluegrass presence and ranged from 16 to 17 mm m−1. Ball bounce and acceleration was measured using a high‐speed camera and object‐tracking software. Annual bluegrass did not influence ball acceleration, but when balls were rolling over annual bluegrass or for the first decimeter after encountering annual bluegrass, ball bounce area was significantly increased. The increased ball bounce was presumably due to textural differences between annual bluegrass and creeping bentgrass and could have contributed to increased ball directional imprecision.