Giving turf the breath of life
Air flow is a major factor for successful maintenance of putting green turf.
Air flow is a major factor for successful maintenance of putting green turf.
Anyone who plays golf knows a green like this. Most superintendents have one. It's located in a low-lying or pocketed environment, where the heat and humidity are stifling compared to other areas of the golf course. A distinct, musty odor is noticeable. The air is stale, and moisture levels are perpetually high. The green just never seems to dry out.
While people may find this environment uncomfortable for a few minutes, golfers can move on to the next hole when play is through. By contrast, the turf on the green continually suffers — the grass is stuck in this environment. The root of the problem is poor air movement, and it can have a devastating impact on putting-green conditions.
Air movement and turfgrass health
The growing environment of the turf on and around a green complex essentially is determined by sunlight penetration and air movement. These factors contribute mightily to the rate at which the putting green complex dries out.
Wet greens are usually bad greens. Excess moisture contributes to increased disease incidence as well as other maladies such as algae. Mechanical damage on greens that do not dry out quickly is even more severe. In traveling the Mid-Atlantic region, the worst greens I see are those located in pocketed growing environments with poor sunlight penetration.
Air movement across the green produces a drying effect for the soil and increases the evapotranspiration rate of the plant. This combination leads to drier conditions and healthier turfgrass.
There is no reasonable substitute for good sunlight penetration of a putting green. Thus, if shade is present, the object casting the shade must be removed if it is causing serious problems. If it is a tree, you can prune it or remove it altogether.
For air flow, however, several options usually are available to improve airflow in a specific area. Removing underbrush and trees can improve air movement, while fans provide an artificial option for increasing air movement. A combination of tree removal and fan installation ultimately may be necessary to improve air movement and the overall growing environment.
- Underbrush and tree removal
Superintendents commonly overlook the impacts of low-growing vegetation when evaluating air-movement problems. However, you need to account for underbrush accumulations around problem green complexes as a first step to improving air movement. It only takes undergrowth 18 to 24 inches high to retard air movement at ground level where the turf is struggling to survive. Removing low-growing weeds and other vegetation within wooded areas adjacent to pocketed greens can have a significant impact on air movement without removing a single tree.
Neglect of underbrush maintenance often starts as soon as construction is finished. Greens that performed well soon after construction can become poor performers over time if underbrush growth is not cut back regularly. The goal should be to remove underbrush annually during the winter months and, if possible, establish vegetation that will persist as a ground cover in wooded areas to suppress the growth of woody perennials.
In more severe cases, underbrush clearing may not be enough. In these cases, significant tree removal may be needed. Tree removal also provides the additional benefit of improved sunlight penetration in many instances. This can create a significant improvement in the growing environment in addition to improved air movement.
Just remember that indiscriminate tree removal is not the best solution. Pay close attention to the prevailing wind direction around a given green before making tree removal decisions. Concentrate on removing trees and underbrush on the side of the green that is exposed to the prevailing winds. Any removal will help, but if the green complex is still blocked on the side of the prevailing wind, you'll derive much less benefit in the way of air movement.
Finally, on deeply pocketed greens, it may be necessary to provide an outlet channel on the downwind side of the green to maximize air movement. For airflow to occur, the air has to be able to leave an area as easily as it enters it. Otherwise, stagnant conditions will persist.
Removal of trees or underbrush is not always possible due to property or environmental constraints. In other instances, the object restricting air movement may not be vegetation at all. Surrounding houses, rock outcrops or even high mounding around a green complex can cause a problem with air movement. In such cases, you may have to use a different strategy.
- Fan installation
When removing the obstruction to air movement is not an option, fans can provide artificial air flow around putting greens. When properly installed and maintained, fans provide a dramatic improvement in air movement and turfgrass health. For the best results with fans, however, you'll need to follow certain guidelines.
Obviously, you should first target the greens with the poorest growing environments for fan installation. The most severely pocketed greens will benefit the most from properly installed fans.
Once you determine the general location of fan installation, you must provide electrical power. This may not sound like a big deal. However, running electricity to the green site is often the most expensive part of the project if fans were not anticipated at the time of construction. The most deeply pocketed greens are often located the farthest from an electrical source.
Tapping into electricity from on-course bathrooms or water fountains is a common choice. Many times the power supply for the irrigation system is considered an option to run fans. Unfortunately, unless fan installation was considered during construction, electrical wiring for on-course irrigation systems won't be sufficient to operate fans.
Sometimes the best option is to tap into a power source from off the golf course property. This often is done in housing developments. It goes without saying that a professional should be hired to perform all electrical installations to be sure they are done safely, legally and correctly.
For the short-term, you can use gasoline engines to run fans, but the need for frequent servicing and the noise make this a less desirable option. However, if you only need a fan sporadically on a green, gasoline power is a viable option.
- Fan type
Fan preference is highly subjective. Regardless of manufacturer, properly installed fans designed for use on golf courses will improve air movement. Superintendents should visit other golf courses that already have fans installed to determine which will perform best for their given situation. Cost of the fan, ongoing cost of operation and noise must all be considered in addition to performance. Be sure to do the homework to find the fan that fits best with your individual circumstances.
- Mounting and placement
Fan mounting will vary with fan type. Most fans are mounted on poles. In some instances, trees can provide an acceptable mount. Fans are generally located behind a green to minimize the impact on play. The goal is to provide a 3- to 4-mph breeze over the majority of the turfgrass canopy on the green. Larger greens may require more than one fan to achieve this.
Proper placement will maximize airflow across the green surface. If the fan is too far away — a common mistake — it will be ineffective in this capacity. For greatest effectiveness, position the fan as close to the green as possible to maximize air movement. However, remember that safety is an issue. Though it would be foolish, the possibility exists that a golfer will stick a golf club in a fan with disastrous results. Guards need to be in place or the fans need to be unreachable to prevent this occurrence.
When determining the height and location of a fan, use a wind-speed indicator to evaluate airflow. This can be as sophisticated as an anemometer that actually measures wind-speed. However, small pin flags or a smoke bomb will provide all of the information you need to determine the fan's impact. Be sure to measure airflow at the level of the turfgrass canopy. This is where the benefit is needed. The airflow should be as uniform as possible across the entire green as the fan oscillates. If fans are not properly located, their value to the turf will be greatly diminished.
Once you've installed the fans, operate them any time when excessive moisture is present and rapid drying is needed. It may be stating the obvious, but fans won't do any good if you don't use them. I've noticed that many golf courses fail to use fans when weather conditions dictate that they should.
Good air movement is crucial for turfgrass maintenance. When possible, the best option for improving airflow around putting greens is to remove trees and underbrush to maximize natural airflow. When tree and underbrush removal are not possible, properly installed fans provide a good alternative to improve the growing environment. The worst thing to do is nothing. Poor growing environments do not improve without help.
Darin Bevard is an agronomist for the Mid-Atlantic region for the U.S. Golf Association (Far Hills, N.J.).
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