Turfgrasses used on sports fields are expected to provide dense, uniform, and safe playing surfaces all season long. However, when turfgrasses face excessive stress from wear or environmental conditions such as heat or drought, pest pressures can become a serious problem. Sports field managers should implement a comprehensive and effective approach to pest management, termed IPM. The Environmental Protection Agency (EPA) defines IPM as an “effective and environmentally sensitive approach to pest management that relies on a combination of common-sense practices.”
An IPM approach considers all strategies to reduce pest damage to manageable and acceptable levels in the most economical way, while simultaneously considering potential impacts on humans, property, and the environment. On sports fields, these programs involve a variety of agronomic practices as well as chemical applications in situations where other means have been exhausted or deemed ineffective.
IPM Overview
IPM is comprised of a range of pest control methods or tactics designed to prevent pests (insects, pathogens, nematodes, weeds, etc.) from reaching unacceptable levels of damage while creating the least risk to the environment. IPM programs have basic components that provide the opportunity to make informed decisions on the control of pests on sports fields. Five basic steps for an effective IPM program for sports fields are as follows:
Step 1: Monitor for pest damage and record the extent and severity of the damage.
Step 2: Identify pests causing damage and understand their biology. Step 3: Determine acceptable threshold levels and continue monitoring. Step 4: Consider a variety of control methods and select the most appropriate.
Step 5: Evaluate the IPM program.
IPM is a flexible approach to pest management. Sports field managers balance sports field quality and environmental goals through IPM implementation. Growing and managing healthy turfgrass is the best and first line of defense against pests. For example, cultural conditions that predispose turfgrass to weeds include heavy traffic, inadequate or excessive nitrogen fertility, frequent or excessive irrigation, inadequate thatch management, and poor drainage. Following cultural, nutrient, and irrigation BMPs can often help alleviate these conditions. However, even under optimal conditions, pests can still sometimes cause excessive damage to sports fields and must be controlled to ensure safety to athletes.
The sports field manager should consider an IPM approach to managing pests as one that provides multiple “tools in the toolbox.” A number of non-chemical and chemical control options are available for use on sports fields. When non-chemical options cannot effectively mitigate a pest problem, selection of an appropriate pesticide should follow an evaluation process that considers potential impacts on beneficial organisms and the environment, as well as the potential for development of pesticide resistance, as discussed in the Pesticide Management chapter.
Identifying and Understanding Pests
Pests must be properly identified in order to be optimally managed. Understanding the biology of pest species and their vulnerable life stages assists with management. Sports field managers and staff should continually hone their diagnostic skills by attending training seminars and field days, obtaining reference materials, and providing peer-to-peer training. Communicate with university Extension specialists to confirm the identification of a pest and seek advice on appropriate control methods.
Weeds
Because of the mechanical stresses associated with normal play on sports fields, bare spots provide an advantageous environment for encroachment by weeds. Over time, weeds can become a persistent presence on the playing surface, comprising player safety, disrupting playability, harboring other pests, and competitively displacing desirable turfgrass, in addition to being unsightly. For example, University of Tennessee research found that natural grass sports fields dominated by weeds, such as large crabgrass (Digitaria sanguinalis L.) and white clover (Trifolium repens L.), significantly compromise both player safety and field aesthetics (Brosnan et al., 2014).
Two major weed types impact field quality and function: annual weeds, such as crabgrass, annual bluegrass (Poa annua), and knotweed (Polygonum arenastrum), and perennial weeds, such as plantain (Plantago spp.), clover, dandelion (Taraxacum officinale), and ground ivy (Glechoma hederacea). While some weeds are easily identified, others may be more difficult. The Weed Science Society of America maintains links to university Extension specialists and other industry experts across the country that can provide more information and weed identification assistance.
Because of the importance of soil quality in growing healthy turfgrass, emphasis should be placed on relieving soil compaction, replacing sod, and testing soil to maintain turfgrass that can withstand pressure from weeds. In addition, cleat seeding/overseeding to fill in voids can help prevent weed germination.
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Minimizing weed pressure can be accomplished with the following cultural practices:
Addressing compaction
Mowing practices
Turfgrass selection
Nutrient management programs
Irrigation
Overseeding
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Irrigation plays an important role not only in influencing weed populations, but also with efficacy of control products. Pre-emergent products form a “barrier” on the soil surface preventing germination of grassy and broadleaf weeds. Products applied to natural grass fields without a natural rainfall event or supplemental irrigation may limit efficacy of the product. Conversely, sites that are over-irrigated may have higher densities of weeds.
Insects/Arthropods
Many arthropods (especially insects and mites) live in turfgrass and ornamental plant beds. Some are beneficial (e.g., pollinators, decomposers, and natural enemies) or are aesthetically attractive (e.g., butterflies), while others may be nuisance pests or may negatively affect plant health, particularly those that feed on turfgrass roots. Arthropods can cause various types of damage to grass plants, depending on where they attack the plant. Annually recurring insect pests that can negatively affect turfgrass include species such as armyworms (Spodoptera spp.), chinch bugs (Blissus spp.) nuisance ants, and annual white grubs.
White grubs can destroy significant areas of turfgrass, with damage appearing when plants undergo stress. Turfgrass is damaged when grubs feed on roots just below the soil surface, reducing the ability of the plants to access water and nutrients required to withstand the stress of hot, dry weather conditions. Drought stress and/or insufficient irrigation may compound this damage. Scouting for these pests is critical as management of white grubs is most efficient when the specific population causing damage is identified, particularly in the first or second instar, early in the life cycle of the insect. Additionally, species identification is also an important
component to effectively managing white grub infestations on sports fields.
Diseases
In general, healthy, well-managed turfgrass better withstands disease outbreaks and recovers more rapidly than stressed or unhealthy turfgrass. Even under favorable environmental conditions when turfgrass is healthy, diseases can develop. The first line of defense to mitigate the severity of disease includes incorporating biological or cultural practices that enhance turfgrass growth, such as the use of improved turfgrass species developed to resist disease.
The second line of defense is effectively incorporating disease diagnosis and treatment into an IPM program. An understanding of the diseases that a given species or cultivar is susceptible to, as well as the environmental conditions associated with the disease pathogens, is essential. Turfgrass diseases most commonly occur in the summer for cool season grasses and the spring or fall for warm season grasses. Scouting for anticipated disease outbreaks as weather-induced stress increases is important. Historical knowledge of past disease outbreaks, in addition to scouting for anticipated symptoms of disease as weather-induced stress increases, can assist in correctly diagnosing the causal agent. Proper diagnosis helps to develop the appropriate IPM protocol to prevent damage to natural grass fields. Diagnostic services, which are often available from a university or from private laboratories, can confirm a diagnosis as well as provide a recommendation for an appropriate management strategy to alleviate damage.
Monitoring Pests and Recording Information
In an IPM plan, pest monitoring or “scouting” efforts should be described for all areas of the playing fields as well as adjacent turfgrass and landscaped areas. Scouting methods include visual inspection, soil sampling, soap flushes, and trapping for insects. Additional monitoring efforts can include use of GDD, which can be helpful for predicting potential weed, insect, and disease development. For example, warmer temperatures combined with high humidity often favor the development of turfgrass diseases such as dollar spot (Clarireedia homeocarpa) and brown patch (Rhizochtonia solani). Additional information can refine predictive models, such as the Smith-Kerns dollar spot model. This model is a logistic-based model that uses a five-day moving average of daily relative humidity and daily average air temperature to create a probability that dollar spot will occur on a given day (Smith et al., 2018). Using this information, managers can accurately time fungicide applications to control dollar spot.
Recording Monitoring Information
When pests are discovered during monitoring, the pest pressure should be quantified with measurements such as:
Number of pests (weeds, insects, disease symptoms) per unit area.
Percent of area affected.
Documentation should include useful information such as photographs, delineation of pest boundaries on an area map, outbreak date, description of the prevailing weather conditions, and recent management practices. This information can be used to build a database for reference in future seasons and for updating the IPM plan.
Growing Degree Days (GDD)
In certain situations, pest management decisions based on GDD accumulation can be more effective than those made using a calendar or schedule-based approach. Growing degree days can be particularly useful for controlling pests preventatively (i.e., before they are visibly noticeable via scouting).
Growing degree days represents the accumulation of “heat units” based on air temperature and can be summarized daily over the growing season. One method of calculating GDD is to compare the average air temperature for a given day to a pre-determined base temperature as follows: (high + low)/2. This difference is summarized over a period of time to represent GDDs accumulated. This information can help predict disease development, insect emergence or development, weed germination, and seedhead emergence of broadleaf and grassy weeds.
If GDD accumulation totals cannot be accessed directly, sports field managers are encouraged to make site- specific calculations using basic weather data from sources such as the National Oceanic and Atmospheric Association. University Extension specialists can provide assistance with making these calculations as well as incorporating use of GDDs into IPM programs targeting weeds, insects, and diseases.
Certain phenological indicators can also be used to optimally time certain pest management applications. For example, crabgrass (Digitaria spp.) germination occurs when soil temperatures exceed 55°F in spring for a continued period. Border forsythia (Forsythia x intermedia) bloom occurs at similar soil temperatures and offers field managers a visual indicator of when to apply preemergence herbicides for crabgrass control. University Extension specialists are a source of information on appropriate phenological indicators.
Determining Threshold Levels
IPM is commonly used in agricultural crop production where economic thresholds for key pests have been established. Using IPM is more challenging on sports fields than in an agricultural setting, as agricultural thresholds are based on crop yield whereas sports field thresholds are qualitative, involving turfgrass density, playability, and safety. These thresholds can be determined scientifically or based on site-specific experience. For example, pest infestations leading to meaningful changes in an assessment score (e.g., PCI score) typically warrant treatment. Ongoing education of athletes, the public, and maintenance personnel often allows for minor aesthetic damage to remain non-treated if it does not hamper sports field safety or quality.
Control Methods
Once a pest problem reaches the established treatment threshold, different methods can be used to control the problem, including cultural, mechanical, biological, and chemical. Selecting the most appropriate approach depends on a number of factors, including the site-specific location on a field, efficacy of control options for the particular situation, economics, and pest populations.
When pesticides are used, whether synthetic, organic, or biological, they must be applied by a state licensed and certified applicator. The use of all pesticides must follow the label and adhere to state and federal regulations, as described in the Pesticide Management chapter.
Role of Cultural Practices in IPM
Cultural practices, especially irrigation, mowing, topdressing, overseeding, and core cultivation, greatly affect both short- and long-term turfgrass health. Especially in times of stress, using and/or altering appropriate cultural practices can be an alternate or supplemental approach to help natural grass better withstand weed, insect, and disease pressure. See Appendix E for more information on the influence of various cultural practices on weeds, insects, and diseases. It is important to recognize that turfgrass management practices such as core cultivation and sand topdressing should occur when plants are actively growing to facilitate recovery. If these practices are implemented when growing conditions are not optimal, they can stress sports fields and make them more susceptible to pest invasion. Cultural practices are not curative. However, when optimized, they render a field less susceptible to pest infestation.
Mechanical or Physical Controls Mechanical or physical control methods can be used to control specific pests, particularly weeds, when overall populations are low. Some methods, such as hand pulling weeds, may be time consuming and labor intensive. Fraise mowing, as discussed in the Cultural Practices chapter, is a tool that has been used to mechanically suppress annual bluegrass (Brosnan et al., 2020).
In situations where the pest pressure exceeds acceptable threshold levels, a partial or full field renovation may be a more effective and economically advantageous alternative to controlling pests. For more information on renovation, see the Planning, Design, and Construction chapter.
Biological Pest Control
Biological pest control (BPC) is gaining increased interest as an option to control insects,
diseases, and weeds. Biological pest control utilizes living organisms, such as bacteria, fungi, or predatory/parasitic agents that introduce natural substances to reduce pest populations. Examples of BPC agents used to manage turfgrass pests are Bacillus thuringiensis var. galleriae, a bacterium that controls white grub species; turfgrass cultivars containing endophytic fungi that deter leaf- and stem-feeding insects; and beneficial parasitic nematodes for chinch bug (Blissus sp.) control. BPCs are applied by licensed pesticide applicators.
Some BPC products can be used as an alternative to synthetic pesticides or in locations where
EPA-registered pesticides are not preferred or permitted. However, the efficacy of many BPC
products currently available for managing turfgrass pests is inconsistent at best. Research is
ongoing to optimize application strategies of these products to achieve better and more consistent control.
Biopesticides
Biopesticides are derived from such natural materials as animals, plants, bacteria, and certain minerals. Biopesticides are classified separately from other pesticides by the EPA and are usually more target/host-specific than conventional pesticides. Biopesticides are divided into three types:
- Microbial pesticides include microbes (e.g., bacteria, fungi).
- Biochemical pesticides include natural substances (e.g., insect hormones) that repel
insects or cause mating disruption.
- Pesticidal substances produced by plants containing added genetic material, called plant-
incorporated protectants.
For more information on biopesticides, see the EPA’s Biopesticide Registration page. For a database of registered biopesticides, see the searchable IR-4 database.
Beneficial Nematodes
Some nematodes, such as Heterorhabditis bacteriophora and Steinernema scarabaei, may naturally suppress insect pests such as white grubs. Nematodes sold for pest management are in the infective juvenile stage, which is the only stage that survives outside the insect host.
To use beneficial nematodes, the following general guidelines should be followed:
Keep nematodes viable until application.
Avoid application during daylight with high UV intensity.
Ensure nematodes can safely penetrate the soil during the application process. Use proper pressure to move the nematodes through the thatch layer and into the soil profile. Maintain agitation of the spray tank so that nematodes are dispersed and do not settle to the bottom of the tank. Irrigate turfgrass areas before, during, and after nematode application to maintain enough soil moisture to allow nematodes mobility as they travel to grub hosts.
More information on nematodes as a control method for turfgrass pests can be found in the University of Connecticut’s Using Beneficial Nematodes for Turfgrass Insect Pest Management.
Chemical Controls
Chemical control is an acceptable IPM practice when other methods cannot alleviate a pest problem. Licensed pesticide applicators are certified by state agencies. The certification process ensures that applicators understand how to use products according to label directions and why it is important to do so. Additionally, these individuals are required to regularly recertify with state agencies every 12 to 24 months to stay current in the discipline of pesticide use. This process ensures minimal risks to applicators, athletes, and the environment.
The selection and use of any chemical control measure should follow these criteria:
Correctly identify a pest to select an appropriate pesticide.
The pesticide selected should be effective in treating the pest problem.
The timing of the pesticide application should be based on the appropriate stage of the pest life cycle to ensure maximum effectiveness.
Any restrictions on the pesticide label must be reviewed prior to application and rigorously followed.
Pesticides should be rotated based on resistance classification specified by the following committees: Fungicide Resistance Action Committee, Herbicide Resistance Action Committee, and Insecticide Resistance Action Committee.
Costs and re-entry period should be considered.
Applications should be made to optimize environmental quality. Consider spot treatments instead of blanket treatments.
Site-specific field characteristics and prevailing conditions should be considered when implementing a chemical control treatment. Factors such as soil pH, soil texture, and organic matter content can affect pesticide effectiveness. Moreover, environmental conditions at application (e.g., soil moisture content, air temperature, humidity, and wind speed) should also be accounted to ensure a treatment performs optimally.
Evaluation and Record Keeping
It is essential to capture and record the results of IPM-related efforts to develop historical information, document patterns of pest activity, and evaluate overall turfgrass health. Records of turfgrass management practices and pesticide use are highly recommended and may be required by state regulatory agencies. State regulatory agencies and university Extension programs may be able to provide sample record keeping forms that meet state regulatory requirements.
For IPM purposes, records should be kept for all pesticide applications and should include additional information, such as monitoring records, weather records, cultural management logs, and pest response.
IPM Best Management Practices
Basic IPM Best Management Practices
Develop a written IPM plan that supports turfgrass health and playing surface safety.
Train personnel to monitor and scout for pests.
Select recommended turfgrass species and cultivars best suited for the intended use and environmental conditions of a specific site.
Correct soil physical and chemical properties that may impact turfgrass ability to resist pests.
Evaluate the potential impact of cultural practices and fertilizer applications on the incidence of pest problems.
Divert traffic away from areas that are stressed by insects, nematodes, diseases, or weeds.
Document all IPM-related activities, including pesticide usage.
Pest Identification Best Management Practices
Identify key pests of turfgrass prevalent to your area.
Determine the pest life cycle and know which stage to target (e.g., for insect pests, whether it is an egg, larva/nymph, pupa, or adult).
For diseases, correctly identify the disease pathogen. This often involves sending samples to diagnostic clinics.
Identify weeds accurately, which can often involve sending samples to a diagnostic clinic.
Where applicable, consider targeted pest control measures rather than blanket applications of pesticides.
Monitoring Best Management Practices
Monitor prevailing environmental conditions for their potential impact on pest problems.
Train personnel how to regularly monitor pests by scouting or trapping.
Identify alternative hosts and overwintering sites for key pests.
When possible, use GDD information to predict pest incidence before it is visible via scouting.
Correctly identify the specific disease, weed, and/or insect problem to ensure appropriate control measures.
Assess pest damage when it occurs, noting particular problem areas, such as the edges of sports fields, shady areas, or poorly drained areas.
Document when the symptoms of pest damage occur, noting the time of day, date, and flowering stages of nearby plants.
Map pest outbreak locations to identify patterns and susceptible areas for future target applications.
Pest Threshold Best Management Practices
Use assessment tools (e.g., PCI score) to evaluate field condition.
Establish acceptable threshold levels for injury caused by key pests and document appropriate treatment options for these pests when these thresholds are exceeded in the written IPM plan.
Weed Control Best Management Practices
To prevent weed encroachment, maintain cultural practices that enhance turfgrass growth and minimize stress from wear, drought, or extreme temperatures.
Repair thin, worn areas or reduce open spaces to minimize exploitation of openings in the turfgrass canopy for weed germination.
To reduce weed infestation, address improper turfgrass management practices, such as mowing height or frequency, irrigation, or fertilization. Additionally, address the negative effects of foot traffic such as soil compaction and mechanical damage to turfgrass.
Fertilize to encourage optimal turfgrass density and vigor to better resist diseases, weeds, and insects.
Materials such as sand, soil, compost, and plant material (i.e., sod, sprigs, seed) from outside sources should be devoid of weeds.
If allowed and necessary, apply a preventative herbicide application to turfgrass to maintain a uniform and safe playing surface. When weeds escape a preventative application, spot- treatments of post-emergence products can be used to control rogue plants when pressure is warranted. Consider both environmental conditions and availability of supplemental irrigation when selecting the appropriate formulation of the control product.
Disease Control Best Management Practices
Encourage proper cultural practices that reduce turfgrass stress and enhance growth.
Select and incorporate turfgrass cultivars or species that are best suited to resist disease.
Review all cultural practices (e.g., mowing, irrigation, and nutrient program) to reduce turfgrass stress.
If necessary, based on weather conditions and historical assessments, apply a preventative fungicide to susceptible turfgrass if unacceptable levels of disease are likely to occur.
Confirm diagnosis of disease pathogen to help select management strategy or to confirm curative treatment to stop disease activity.
Insects/Arthropods Control Best Management Practices
Identify key regional insect pests.
Select and incorporate endophytic turfgrass cultivars into seed mixtures that deter surface-feeding insects.
Review all cultural practices (including mowing, irrigation and fertility program) to reduce turfgrass stress.
For preventive insecticide applications, especially those that contain a neonicotinoid product, mow turfgrasses that contain populations of clover or any flowering weed, to reduce foraging traffic of bees.
For insecticide application aimed at targeting root-feeding insects, irrigate turfgrass before and/or after an application, in accordance with the label.
Biological Pest Controls Best Management Practices
To support efficacy and application of BPC products aimed to control surface or thatch dwelling insects, as well as root-feeding insects such as white grubs, irrigate turfgrass before and/or after an application, in accordance with label instructions.
Consider timing applications to coincide with appropriate soil temperatures, active soil microflora, and the life cycle of a targeted insect pest.
Follow guidelines for utilizing beneficial nematodes in order to increase efficacy.
Chemical Pesticides Best Management Practices
Train employees in proper pest identification and pesticide selection options.
Select the best pest-specific product to optimize environmental quality and safety.
Ensure that any chemical applications are made by licensed applicators or supervised by licensed applicators, following state pesticide regulations. Follow all BMPs related to chemical handling and application.
Time pesticide applications for the appropriate stage of the pest life cycle to be controlled to maximize effectiveness.
Review and follow all restrictions on pesticide label prior to application.
Rotate pesticides based on resistance classification.
Consider costs and re-entry periods in product selection.
Record Keeping and Evaluation Best Management Practices
Observe and document natural grass conditions regularly using approved assessment forms (daily, weekly, or monthly, depending on the pest). Note which pests are present so that informed decisions can be made regarding the damage they are causing and what control strategies are necessary.
Determine whether the corrective actions effectively reduced or prevented pest populations. Record and use this information to assist in making similar decisions in the future.