Karl Danneberger, Ph.D
When turfgrass growth becomes horizontal, the leaves begin to lie in various directions. We call this grain. Oftentimes with grain, turfgrass leaves are sporadically coarse in nature, which contributes to a general roughness of the turf. Golfers view grain that occurs on putting greens negatively in that it impacts putting green consistency. If you putt with the grain (leaf blades lay away from you), the ball will tend to roll further or be faster than if you are putting against the grain (the leaf blades lay toward you), which will be a much slower putt.
Similarly, golfers may read a putt by looking at the way the grain lays between the golf ball and the hole. If the grain is toward the golfer, the turf may appear a little darker green, or conversely, if it lays away from the golfer, the turf may be a little lighter color. Grain can impact the amount of break in a putt.
Grain is often associated with the growth habit of the turfgrass species. For example, creeping bentgrass is prostrate in growth while annual bluegrass grows more upright. Bermudagrass greens — including the ultra-dwarf varieties — frequently develop grain. Grainy patches develop, which contrasts between the green areas and lighter green patches. Superintendents may describe the patches or areas that develop on a bermudagrass green as grain, but the cause may be due in part to genetic mutations.
Managing grain consists of repetitive practices that are often ingrained — no pun intended — on a daily basis, like mowing. Mechanical practices to remove grain and improve texture include mowing (frequency, height, direction), verticutting, grooming (groomers), brushing and topdressing. The goal is to get the turfgrass plants to grow vertically or upright, thus removing grain and improving the density and texture of the turf.
Mowing greens are probably the most consistent means of reducing grain. To improve leaf texture and help remove grain, consider changing mowing height, frequency and direction. Lower mowing heights tend to increase density resulting in a finer texture and reduced grain.
Frequently changing the direction of mowing can help remove grain by forcing the turf plant to grow more upright vs. mowing in the same direction, resulting in the plants laying in one direction. Grooved rollers on greens- mowers tend to stand the plant up prior to being cut by the mowing unit, especially compared to solid rollers.
For the last several years, we have looked at the impact of brushing, including the evolution in brushing equipment on removing grain and improving putting green turf health. In our field day presentation this year, we will look at relatively low-cost methods of brushing. We are studying the impact of the brushing units on plant stress, green speed and overall quality, which is primarily the reduction of grain.
Of the remaining practices associated with managing grain — verticutting, grooming (groomers), brushing and topdressing — we studied brushing as the equipment has evolved and as a management practice.
With brushing units placed in front of the cutting unit and behind the front roller, we found brushing to be an effective method for reducing grain with little impact on plant health or playability of the putting surface.
As our ability becomes increasingly effective with removing grain, I wonder how much time golfers spend look- ing for it as they line up a putt.
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