Imagine
yourself playing golf with friends or family on a warm summer day. Everyone is enjoying their rounds and then
you get to that one green. Suddenly the
air feels stagnant and hot, you start to sweat more, your clothes stick to your
body, and you can’t wait to get to the next hole where there always seems to be
a nice cooling breeze. Now imagine
staying on that green the whole day, throughout the entire summer, with endless
hot, humid days without any relief from a cool breeze. Pretty miserable, right? Well that’s exactly what the putting green
turf suffers through when it is located in a microclimate that has limited air
movement.
The
microclimates in which putting greens are located play a major role in the
superintendent’s ability to produce good golf conditions. Many articles have been published in the Green Section Record about the negative effects
that shade has on putting greens, but only a few articles discuss the
consequences of poor air movement.
Research and field observations are
very clear that putting greens can be greatly improved with the use of fans
because of the cooling effect on the turf canopy, soil temperature, and
increased root development (Duff and Beard, 1966; Guertal et al., 2005). Fans also help to dry the soil and reduce
turf leaf wetness duration, both of which reduce pathogen pressure. Using a fan to dry the surface improves putting
green wear tolerance, too. Oppressive
heat and humidity makes it next to impossible to grow healthy creeping
bentgrass or Poa annua putting greens
during the summer in the Southeast Region and Transition Zone if air movement
is limited. As a result, most golf
courses in the Southeast that have creeping bentgrass or Poa annua rely on fans to keep putting greens healthy during the
summer (O’Brien, 2009).
Farther
north, the use of fans has slowly become more common in the past decade, but
many facilities are still hesitant to install them. So why is there still resistance to the use of
fans in the Northeast? Cost of fan installation and operation is one reason. The perceived disruption to the game of golf
and their unattractiveness probably plays a bigger role. Finally, many golfers still feel that fans
are necessary only in the Southeast or Transition Zone and not important in the
Northeast. This couldn’t be further from
the truth.
Obviously, the Northeast doesn’t
experience periods of heat and humidity for the same duration as the Southeast
or Transition Zone, but that has no bearing on whether a fan is necessary. Instead, these conditions suggest that fans need
not be operating for as long a period in the Northeast. For instance, fans run in the Southeast from May
through October, while the Northeast may need fans only during June, July, and August. The bottom line is, restricted air movement
leads to poor putting greens in all parts of the country. It’s not just a Southeast or transition zone
problem.
Evaluating Air Movement
Across Putting Greens
Some putting greens are obvious
candidates for fans if they are encircled by dense vegetation, are pocketed, or
are located in low-lying portions of the golf course. Evaluating air movement is easy-to-do with
the use of hand-held wind meters that measure wind velocity. Next, determine air movement direction with a
smoke bomb or similar device (Zontek, 1992).
Correlate this information with past green performance, and it should be
easy to identify which microclimates are in most need for additional air
movement. Turf canopy thinning, algae,
disease, and excessive moisture retention are common maladies of putting greens
with poor air movement to look for during the evaluation process. Keep in mind that fans are not a substitute
for tree removal, but some microclimates could require the removal of hundreds
of trees to improve air movement, which is why fans are so beneficial.
Fan Placement is Key
Fan technology has remarkably
improved since their early use. Small,
loud fans that improved air movement over a small area have been replaced with
large, quiet fans that can improve turf conditions over a much larger area
through slow oscillation. Fans work
similarly to automatic irrigation heads.
Air movement is greatest near the fan and declines gradually the farther
away from the fan. Consequently, fans
can be misused when poorly placed. Fans
installed far away from putting greens to camouflage their existence usually benefit
the rough near the green complex, but provides little, if any, improvements to the
green. Don’t fall into this trap. Just because larger fans can improve air
movement over bigger area doesn’t mean they should be placed farther away from
the surface. If the fan is farther than 20 feet from the green
surface, it’s not likely to benefit the entire putting green. Also, fans should be placed in the area that
is most in need of air movement. All too
often, fans are hidden so players don’t see the fan from drive zone. Sometimes this works, but, in most
situations, a fan placed directly behind the green (in clear view) is most
beneficial because the oscillation will allow for the entire green to benefit. Portable fans installed on easily moveable
trailers are a relatively new method to use fans when and where necessary. Like permanent fans, though, they need to be
close to the putting green to improve air movement significantly.
Fan height is usually 10 feet or less to maximize
air movement across the surface of the green.
The angle of attack also should be considered to maximize the benefit of
fans. Seeing the moving flag on the
flagstick is a good sign, but the air movement at the turf surface could still
be stagnant. During installation, place
irrigation flags throughout the green so that the miniature flags are three
inches above the turf surface. Adjust
the fan angle according to the movement of these flags. In most instances, this requires the angle of
attack to be pointed toward the turf more than you would have otherwise. The ultimate goal with fans is to increase
air movement by 3-5 mph
across the entire putting surface. If
this isn’t achieved, adjust the fan placement, height, or angle as needed.
Fan Use
Fan use is most needed during the
summer months, but stressful weather in the spring has been common in the past
few seasons, so don’t wait to get them set up.
Running fans 24 hours a day during periods of heat and humidity is
common. If fans can’t be used for 24
hours, operating them from the evening to early morning hours may offer the
most benefits with respect to alleviating heat stress and increased rooting (Haung
et al., 2001).
Conclusion
The summer of 2010 was extreme, and
putting greens with poor air movement declined throughout the Northeast. Many facilities learned the hard way that
fans can make the difference between a good and terrible golf season. The agronomic benefits of fans cannot be
disputed. The game of golf is played on
grass, and fans may be necessary to produce healthy grass on golf courses, even
in the Northeast. You might even play
better golf on that green that used to make you uncomfortably hot and sticky in
years past.