Maintaining the Trees and Shrubs at Sports Fields and Facilities
By John C. Fech
Trees and shrubs have been placed at your sports field for several reasons. They bring a lot of value in terms of amenity and shade to a sports facility, but if neglected can turn from an asset into an eyesore. Here’s how to keep them looking and functioning great.
Before attempting to maintain anything – a car, a shopping mall, an air conditioning unit, a church building – it’s crucial to identify the exact specifics at hand. After all, Ford parts just don’t work well for a Dodge pickup. In this application, knowing that Ficus, viburnum, juniper and maple are the plants in the planting beds that need to be maintained establishes the foundation for any actions going forward. Each of these plants has unique needs that must be met in order for it to thrive; if those needs aren’t met, the plant will struggle and become a drag on the facility.
An inventory can be a simple procedure. Starting with a simple sketch of a field or group of fields, simply draw in the hardscape features (such as the parking lots and concession stands), then the actual fields, then the plantings. At this point, it’s best to draw ovals, circles, rectangles and other geometric shapes instead of getting real detailed. An overall view document of this type is called a bubble diagram – one that establishes the size and shape of the sports field landscape.
After the bubbles have been located, take each one and draw it again, at least large enough to fill an entire page of graph paper or legal paper. This will provide the space necessary to be specific regarding the identity of each plant and its needs. Next, draw the smallest and lowest-to-the-ground plants, usually the short shrubs and hedges. Then draw in any trees that cast shade over the top of them with a rough wavy circular line, using a different color. If you know the names of the plants, great; go ahead and write them in at this point. If not, seek out their identity. Nursery vendors, experienced landscapers and university extension faculty are great resources for this, as well as some of the smart phone apps that utilize recognition software. Label each plant or plant grouping with a corresponding letter, such as Group A = mass of Ficus, Group B = 2 hackberry, Group C = 7 lilacs, etc.
The right or left hand side of the enlarged bubble is a good location for each group and its associated needs. For example, Group C, the lilacs, would be headed with “7 Miss Kim Lilacs,” susceptible to oyster shell scale, scout for that in May; prune out the oldest stems after blooming; don’t need much in the way of fertilizer. Group A would be described as “Weeping Fig,” inspect for mealybugs throughout the season; fertilize lightly every two months; keep roots moist, not soggy or dry with drip system. The expected benefits for each planting – such as shade for the bleachers or screening between fields – should be noted as well.
After each field is inventoried, the plantings need to be assessed as well. This essentially involves making a determination of their condition in terms of pest presence, need for pruning/rejuvenation, and stability. This is especially true in terms of moderate to large trees; when neglected for even a short period of time, they can develop defects such as cracks, co-dominant leaders and poorly attached limbs. If assistance is needed to obtain this information, an ISA Certified Arborist can provide his or her expertise. In addition to overall condition, a Certified Arborist can recommend currently approved arboricultural practices that can stabilize a tree and make it safe for spectators to sit beneath (nobody wants a limb falling on a soccer club booster).
The Certified Arborist can also identify and evaluate the significance of any poor practices that have been conducted in the past. Ill-advised tree care practices – such as lion’s tailing, topping, flush cutting and long-term cabling/bracing – usually have long-lasting effects on a tree’s health, and increase the odds of tree failure and harm to people nearby. If the arborist recommends pruning, fertilization, pest control or removal, it’s wise to take their advice. ISA Certified Arborists, particularly those with Tree Risk Assessment Qualifications (TRAQ) can be a real asset in the overall management of a sports complex, and can greatly reduce liability from poorly maintained trees.
In addition to the individual trees and shrubs themselves, time and effort should be given to assessing the site as well. Factors such as soil drainage, slope, fertility, sunlight exposure, irrigation system efficiency and soil pH are very influential in the overall success of the plantings. At a minimum, these factors should be taken into consideration when specimens are failing. The better approach would be to take a proactive stance and consider each of the specific needs of the plants and match them with the site conditions, noting where discrepancies exist.
The turf is king
Let’s face it; in the overall sense, we’re talking about the care and function of sports fields. As such, turfgrass health, vigor and performance must always be the most important factor and focus of attention by a sports field manager. Yes, in many situations, trees, shrubs and other plants are a part of the overall landscape, but keeping the turf as the number one element provides a valuable perspective and is instructive when it comes to the maintenance of ornamentals.
Many examples of turfgrass vs. trees/shrubs can and should be considered. Perhaps the most obvious is the shade produced by trees. If a tree casts a heavy shade on a field, it’s depriving the field of an essential input. Both quality (the intensity) and quantity (number of hours received) of sunlight are influential. Other considerations include the time of day and direction that shade is cast. A tree on the south side of the field will provide a greater reduction in the amount and intensity of light received by the turfgrass than one on the east side.
The tree itself, in terms of the canopy density and actual shade pattern is a consideration as well. Oaks and maples produce much denser shade than honeylocust and eucalyptus. Shorter trees – such as Japanese tree lilac, crabapple and hawthorn – may provide visual relief and screening with minimal shading effects on the turf.
Turfgrass functions themselves are impacted by the presence of trees. Bermudagrass, zoysiagrass, tall fescue, perennial ryegrass and Kentucky bluegrass all differ in terms of their need for sunlight. When turfgrass experiences shade stress, the cell walls become thinner and the leaf blades elongate. This leads to a downward spiral in many cases, with higher than optimal humidity; reduced root growth in favor of shoot production; and a greater susceptibility to diseases such as stem rust, powdery mildew, brown patch, leaf spots and pink snow mold. Regular disease scouting is recommended under these circumstances.
A more subtle, but equally important, consideration is the competition for moisture and nutrients. When placed closely to the sports field, trees often cast excessive shade, but also develop roots that extend into the turfgrass area. Of course, each tree species (as well as individual specimens in a given species) is different in this regard, but a good rule of thumb is that the lateral expanse of roots is equal to the height of the tree.
Fortunately, sports field managers have a wide variety of tools available to them to deal with these issues – including light meters, apps, soil moisture probes and even consultants that specialize in the tree vs. turf quandary. The bottom line when it comes to this crossroads of turf and tree management is twofold:
1. Be careful trees and shrubs don’t cast too much shade
2. Monitor for the development of roots that compete excessively with turf for water and nutrients
When it comes to creating a schedule for maintenance, it should be done with the inventory and condition assessments in hand. As noted, certain species, such as pin oaks, are inherently susceptible to scale insects, but certainly not each and every year. This establishes a need for regular scouting and treatments based on the presence of pests at an actionable level. Yes, the knowledge that a certain disease or insect is likely to become infested or infected is really helpful in terms of knowing what to look for, but it’s the actual presence that helps pull the trigger in terms of pesticide application. Also, keeping good records of treatments is really helpful for future management, because, in most cases, common pests of trees and shrubs usually take two to three years to control. Scheduling those applications in years 1, 2 and 3 increases the chances of success.
Pruning need is also a practice that should be coordinated with the inventory and analysis. Noting issues to be addressed utilizing recommendations from an ISA Certified Arborist (pruning, fertilization, growth regulator usage, expansion of mulched areas) on a weekly or monthly basis keeps tree and shrub maintenance on track throughout the season. For example, when scouting for pests, a technician should also notice if the mulch around a tree/shrub has blown away and needs to be replaced. Probing the soil for moisture level is a similar activity that should be done on a regular basis. Simple tools such as a headless golf club, screwdriver or piece of rebar are essential for determining soil moisture content for both trees and turf.
Especially if the sports facility is large, there will be several trees each year that need to be removed – both for the benefit of the turf and the reduced liability for the spectators, players and coaches. Though removals can be done whenever it’s convenient, scheduling them when play is at its lowest point (a.k.a., the off season) is the best approach. After all, if the arborist has the option to drop the tree horizontally as well as to cut off branches piece by piece, the cost and liability will be much less.
Long-term sports facility users may object to tree removal, especially if they have enjoyed the many benefits of trees-in-place over the years. Removal means an immediate loss of shade, and creates an openness that they might not be expecting. As a sports field manager, it’s crucial to support your decision to remove the tree based on the performance of the turf and safety to the people using the fields. Keeping a maintenance book with documented original purpose, benefits, annualized costs of maintenance, potential liability, turfgrass performance over time, recommendations from ISA Certified Arborists, and intended replacements will bolster your case.
John C. Fech is a horticulturist with the University of Nebraska-Lincoln and certified arborist with the International Society of Arboriculture. The author of two books and more than 400 popular and trade journal articles, he focuses his time on teaching effective landscape maintenance techniques, water conservation, diagnosing turf and ornamental problems, and encouraging effective bilingual communication in the green industry.