Dull blades open turfgrass to disease and poor performance.
May 8, 2018 By Mike Jiggens
Sharp mower blades promote healthier turf. When they’re dull, it makes turf more prone to disease, and golfers will see first-hand how substandard a course looks and how poorly it performs.
Doug Veine, territory manager for Bernhard Grinders, told an audience of golf course technicians attending the Canadian Golf Course Management Conference in February that they have an important role to play in the turf quality at their respective golf courses.
“We want our golf courses to look really good,” he said at the Quebec City conference. “We know what it’s like when mowers cut well. It’s a good feeling to see how well those mowers cut.”
When a golf course fails to achieve a clean cut, it leaves a negative impression among golfers. Veine said the idea is to entice golfers to recommend the course to others.
The healthier the turf, the healthier a club’s bottom line is apt to be. He said there is nothing attractive about scalped or damaged turf, and it’s usually because the cutting units haven’t been properly set up.
“We know what it looks like when it cuts well. Unfortunately, we also know what it’s like when it’s not.”
Reels must be kept clean and sharp, Veine said, adding, “Sharpening a cutting unit needs to really have a thought process along the lines of preventative maintenance.”
A mower is saying something when it can’t cut a piece of paper during setup, he said. It may just be the bedknife, or the bedknife and the reel, or it may simply need an adjustment. But it’s crucial that mowers are checked each time before they go out.
“To maintain that adjustment and keep it proper is going to affect the way it cuts.”
The bedknife is the place of most wear in a cutting unit and is the cheapest piece to replace. It is the point where everything is measured – where the cut is set or the bedknife to reel adjusted. In some situations, it’s the reel to bedknife adjustment, but in most cases the bedknife adjusts up to the reel.
Veine looked at the history of mower evolution, noting that historically the scythe preceded the mower. It, too, had to have a sharp blade to work effectively. He said mower science still holds true through the years, adding the cutting unit dynamics are one thing that hasn’t changed. Blades have been added, numbering anywhere from five to 15, but they still have to spin and go across the bedknife to make a cut.
“Consistent proper cutting units have the single greatest impact on how your golf course looks and plays.”
It is important that each cutting unit on a triplex mower is set up exactly the same. If one unit has a groomer and another doesn’t, the turf’s appearance may be off, he said, admitting that it can be difficult sometimes to tell if one groomer is on and another is off.
If two walk-behind units are being used to mow the same green, double cutting in two different directions, it is important they are set up similarly.
“Are they using the same number of blades? Is one mower different from the other?”
Dull blades can lead to disease
Veine likened sharpening mower blades to changing the oil in a fairway mower. An oil change can’t be done only once per year, and neither should blade sharpening be done only once annually. When blades are rendered dull, they will simply tear the grass blades, leaving them susceptible to disease.
“The more damage there is to the leaf tissue, the greater the disease pressure.”
Cutting units should be sharp day in and day out, especially going into the winter, Veine said. Some courses may figure they can get away with dull blades for their final few late fall cuttings before making their snow mould applications. When one of the more expensive fungicides is being applied, it’s advantageous to make the final cuts with sharp blades that leave a clean cut than having dull blades that will only tear the leaf blades as they enter dormancy.
“How much more effective will that chemical be?”
If even one chemical application can be avoided, a notable cost savings will result, not only in the cost of the product itself but with the labour involved.
“If you can get away with half a pound less nitrogen per year because your grass is healthier and it’s not stressed out and you’re not trying to pump that through the plant tissue, it’s something to think about.”
Sharp blades produce sharp-looking turf that makes both the technician and golfers feel good. It makes a positive contribution to not only the maintenance department, but the entire golf operation.
“Mowers that have just been sharpened produce the fastest speed and the most accurate ball roll and the smoothest surface. It’s all about the consistency.”
Although it’s important to have sharp blades when cutting fairways, tees and approaches, they are especially crucial on greens. When leaf blades are torn, the ball is apt to roll less true and will lead to golfer frustration.
Agronomic practices such as aerating and topdressing stress the plant in the short term, making it more imperative to mow afterwards with sharp blades, Veine said. He added that topdressing dulls the reels and bedknife. Sharpening should therefore be done following topdressing.
The proper setup of cutting units is a vital first step to achieving consistency.
“You’re not going to take a 14-blade reel out that’s designed to mow grass between 100,000th and 200,000th of an inch and go mow your rough with it. It’s not going to look very good.”
Veine said the right cutting apparatus must be available for the specific mowing job. Operators need to know their cutting heights, that adjustments are made from the rear, and that groomer heights are both set the same. If one groomer is a quarter-inch off from the other, the cut appearance is apt to be compromised.
Veine reminded the technicians in his audience to always consider the bedknife attitude, noting it will change with bedknife wear.
“Properly adjusted mowers stay sharper for longer and do less damage to the turf.”
A healthy final cut in the fall should be the goal before turfgrass is put to sleep for the winter, he said.
“See if it makes a difference in your fungicide application. It definitely can’t hurt. If anything, it’s going to improve.”
Double cutting with dull mower blades versus single cutting with sharp blades may achieve the same ball speed on a green, but cutting with a sharp blade reduces fuel consumption by half and saves on labour.
“Don’t stress your grass out. Sharpen your mowers regularly. Consistency matters. It matters to the turf. It matters to your customers. It matters to the overall appearance.”
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