7 Integrated Pest Management
When turfgrasses face stresses such as the heat and drought found in Virginia’s transition zone climate, pests can become a problem. Pesticides alone will not control pests; a more effective approach is to develop an IPM program to reduce pest damage and reliance on pesticides. The EPA defines IPM as “an effective and environmentally sensitive approach to pest management that relies on a combination of common-sense practices.”
The primary objective of an IPM program is to reduce the total pesticide load on the golf course by using a combination of tactics to control or manage pests. This approach considers all strategies to reduce pest damage to acceptable levels in the most economical means, while simultaneously accounting for impacts on humans, property, and the environment.
7.1 Regulatory Considerations
7.1.1 Pesticide Usage
As described in detail in the next chapter (“Pesticide Management”), pesticide usage needs to follow state and federal regulatory requirements. The label is the law and must be followed at all times.
7.1.2 Prescribed Burns
Prescribed burns can be part of an IPM program to control weeds and other growth. State law (9VAC5-13) allows open burning for forest management and agricultural practices, provided the burn is at least 1,000 feet from any occupied building unless the occupants have given prior permission, other than a building located on the property on which the burning is conducted. The burn must also be attended at all times. Some local ordinances may supersede state laws and regulations, so local government should be contacted prior to initiating a prescribed burn.
7.2 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 economically or aesthetically damaging levels 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 at a golf course. Five steps for an effective IPM program for turf are as follows:
Step 1: Monitor pests and their damage and record information.
Step 2: Identify pests and understand their biology.
Step 3: Determine threshold levels.
Step 4: Consider a variety of control methods.
Step 5: Evaluate the IPM program.
IPM is flexible, and superintendents can usually balance course quality and environmental goals through its implementation. Growing healthy turf is the best and first line of defense against pests. For example, cultural conditions that predispose turfgrass to diseases include close mowing, inadequate or excessive nitrogen fertility, frequent or excessive irrigation, inadequate thatch management, poor drainage, and shade. Following cultural BMPs and nutrient BMPs can help alleviate these conditions. However, under the right conditions, pests can sometimes cause excessive damage to highly managed turfgrass.
A number of non-chemical and chemical control options are available. When chemicals are needed, 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. Pesticide products should be rotated, based on their resistance classification.
7.3 Monitoring Pests and Recording Information
In the IPM plan, pest monitoring or “scouting” efforts should be described for all areas of the course such as putting greens, tees and fairways, roughs, and landscaped areas. Scouting methods include visual inspection, soil sampling, soap flushes, and trapping of insects. Additional monitoring efforts can include weather tracking, which is especially helpful for predicting potential disease outbreaks. Here is one potential scouting schedule: daily on putting greens, at least weekly on tees and fairways, twice a month on roughs, and whenever the potential for pests increases due to weather. For example, warmer temperatures combined with high humidity favor the development of diseases such as dollar spot and brown patch.
When pests are discovered during monitoring, the pest pressure should be quantified with measurements such as:
- Number of insects per unit area.
- Disease patch sizes.
- 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.
7.4 Identifying and Understanding Pests
Once detected, pests must be properly identified. Understanding the biology of pest species and their vulnerable life stages assists in later control efforts. Just as important as identifying pests is recognizing and understanding beneficial organisms and their life cycles so their populations are not unduly negatively affected while managing pests. Superintendents and staff should continually hone their diagnostic skills by attending training seminars and field days, obtaining reference materials, and providing peer-to-peer training.
Both warm- and cool-season turfgrasses are susceptible to a number of diseases. In many cases, diseases develop when conditions are favorable, regardless of management strategies. However, the severity of disease is often greatly reduced by using cultural, biological, and genetic techniques. As a rule, healthy, well-managed turf better withstands disease outbreaks and recovers more rapidly than unhealthy turf.
In order to effectively treat turf diseases and implement an IPM program, it is important to know which disease is most likely to be active. Managers who do not understand disease pathology risk treating the symptom, rather than the underlying disease. Turf diseases are typically most common in the summertime for cool-season grasses and in the spring and fall for warm-season grasses. These diseases occur largely due to the shift in growth habits of the grasses from active growth to survival, giving a competitive advantage to disease pathogens.
Understanding the potential diseases for a given species or cultivar and the environmental conditions associated with them is essential. In situations where diseases develop, proper diagnosis assists with decisions on how best to proceed. Diagnostic services are available from the Plant Disease Clinic at Virginia Tech and private laboratories and can help prevent choosing the wrong products or management tactics. Some of the more common golf turfgrass disease problems are described in Table 15.
Table 15. Common golf turfgrass diseases
|Conditions Favoring Disease Development||Disease (Common Names)|
Weeds are unwanted plants that are unsightly, disrupt playability, harbor pests, and competitively displace desirable turfgrass. Bermudagrass may be a desirable turfgrass on a golf fairway but be a serious weed in the neighboring golf rough, tees, or putting greens. Weeds exploit openings in the turfgrass canopy, where seedlings germinate and survive to become a persistent colony of perennials or seed-producing annuals.
The potential for invasive weeds can be limited through implementation of the BMPs identified in this document related to turfgrass selection, nutrient management programs, irrigation, and cultural practices. For example, sites that are over-irrigated may have higher densities of weeds, such as green kyllinga or yellow nutsedge. Cultural practices, such as mowing height, frequency, and maintenance, can also impact turf weed populations. For example, not following the one-third mowing rule and mowing too short can open the canopy and provide a competitive advantage to germinating weeds. Because of the importance of soil quality in growing healthy turf, emphasis should be placed on soil testing for the maintenance of turf that can withstand pressure from weeds.
Virginia Tech’s Weed Identification web page offers identification images and text on hundreds weeds of Virginia and surrounding areas. VCE also offers free weed identification and control recommendations though its county agents. Fresh plant samples can be placed in a re-sealable storage bag and mailed to the Virginia Tech Weed Clinic or a County Extension Office.
Plant-parasitic nematodes adversely affect turfgrass health by debilitating the root system of susceptible species, thus decreasing the efficiency of water and nutrient uptake. Turf weakened by nematode infestations favors further pest infestation, especially weeds. Over time, turf in the affected areas thins out and, with severe infestations, may die. Turfgrass often begins showing signs of nematode injury during additional stresses, including drought, high or low temperatures, and wear. Sampling is recommended to identify nematodes and to develop threshold levels and treatment strategies.
Annually recurring insect pest groups on Virginia golf courses include numerous species:
- Armyworms, cutworms, and sod webworms (Lepidoptera).
- Nuisance ants and red imported fire ant (Hymenoptera).
Occasional pests include the northern mole cricket (Orthoptera) in sandy soils and common chinch bug (Hemiptera).
White grubs are the larval stage of a group of beetles collectively known as scarabs (family Scarabaeidae). Among the white grub species causing turf injury in Virginia are:
- Several annual white grub species.
- Black turfgrass ataenius, Ataenius spretulus.
- Annual bluegrass weevil (Coleoptera).
White grubs can destroy significant areas of turfgrass, with damage appearing in summer. Summer drought stress and insufficient irrigation may compound the damage to turf by grubs burrowing into grass stems. For more information on IPM methods and control methods specifically for annual bluegrass weevils, see Diagnosis and Decision Making for Sustainable Annual Bluegrass Weevil Management, New York Golf Course Foundation and Cornell University.
7.5 Determining Threshold Levels
A key feature of IPM programs is the identification of tolerance thresholds. Thresholds are based on the pest population, the stage of the pest, and the life stage of the plant. Injury thresholds represent the pest level population that causes unacceptable injury. Treatment thresholds are less than the injury threshold and indicate the number of pests or level of damage that would justify treatment to prevent the pest population from causing unacceptable turf loss.
7.6 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 the golf course, efficacy of non-chemical controls for the particular situation, economics, and pest populations.
7.6.1 Cultural Controls
Cultural practices, especially irrigation, mowing, topdressing, core cultivation, and venting, greatly affect both short- and long-term plant health. Using and/or altering cultural practices, especially in times of stress, to keep plants and soil healthy helps turf to better withstand pest pressure. It is important to recognize that turfgrass management practices such as core aeration and sand topdressing, while beneficial, can also stress turfgrass.
7.6.2 Mechanical or Physical Controls
Mechanical methods, such as vacuuming, or physical control methods, such as hand pulling weeds, exclude or remove pests, though these methods may be time consuming and work best when pest populations are low.
7.6.3 Prescribed Burns
As golf courses convert maintained turfgrass areas to native-grassed sanctuaries, many facilities use prescribed or controlled burns to reduce undesirable plants, including noxious weeds, and to encourage desirable species, enrich wildlife, and remove excessive plant debris. Prescribed burns are especially effective in suppressing cool-season grasses and woody plant materials to create a more desirable stand of a links-style course that resembles a tallgrass prairie. Use of a prescribed burn, along with other control methods, is an IPM approach to effectively manage these eco-sensitive areas. For more information, see “Beyond the Bonfire: A Primer on Prescribed Fire for Virginia’s Private Landowners.”
As noted in the “Regulatory Considerations” section of this chapter, any local notification requirements should be followed as required and all fire danger information reviewed before conducting a controlled burn.
7.6.4 Biological Controls
The biological component of IPM involves the release and/or conservation of natural predators, such as parasites and pathogens, and other beneficial organisms. Several organisms known to have some efficacy against turfgrass pests have been marketed as pest control products, such as such as Bacillus licheniformis. Natural enemies (e.g. ladybird beetles, green lacewings, and mantids) of some insect pests may be collected or purchased and released near pest infestations. Areas on the golf course can also be modified to better support natural predators and beneficial organisms, especially in landscaped areas.
7.6.5 Pesticides/Chemical Controls
Chemical control is an acceptable IPM practice when other methods will not alleviate the pest problem. In addition to traditional chemical control, reduced-risk pesticides and biopesticides provide a number of advantages over conventional pesticides and should be considered if applicable. The selection and use of conventional pesticides should follow a selection process and these criteria:
- Use a recommended product to treat a correctly identified pest. See Chapter 7 of the 2020 Pest Management Guide: Horticultural and Forest Crops, VCE.
- The pesticide should be effective in treating the pest problem.
- The timing of the pesticide application should be based on GDD information for the pest to be controlled. GDDTracker is an example of a tool that can assist in timing applications.
- Pesticides should be rotated, based on resistance classification, as classified by the Fungicide Resistance Action Committee (FRAC), Herbicide Resistance Action Committee (HRAC), and Insecticide Resistance Action Committee (IRAC).
- Costs should be considered.
- Environmental risk and potential for water quality impacts must be evaluated.
- Any restrictions on the pesticide label must be reviewed and rigorously followed.
Evaluating the environmental risk and potential for impact on water quality can include the use of software, such as the Windows Pesticide Screening Tool (WIN-PST), which was developed by the NRCS to evaluate the potential of pesticides to move with water and eroded soil/organic matter and to affect non-targeted organisms. WIN-PST users can select combinations of active ingredient, soil type, and growing conditions to select an active ingredient that has less potential to leach and/or run off into surface water.
The use of all pesticides must follow the label and adhere to state and federal regulations, as described in the “Pesticide Management” chapter.
Reduced Risk Pesticides and Biopesticides
The EPA’s Conventional Reduced Risk Pesticide Program registers reduced-risk pesticides, which are commercially viable alternatives to conventional pesticides. The EPA characterizes the advantages of reduced-risk pesticides as follows:
- Low impact on human health.
- Lower toxicity to non-target organisms (birds, fish, and plants).
- Low potential for groundwater contamination.
- Low use rates.
- Low pest-resistance potential.
- Compatibility with IPM practices.
Biopesticides, which are derived from such natural materials as animals, plants, bacteria, and certain minerals, are classified separately by the EPA. For more information on biopesticides, see EPA’s Biopesticide Registration page.
7.7 Evaluation and Record Keeping
It is essential to record the results of IPM-related efforts to develop historical information, document patterns of pest activity, and evaluate successes and failures. Records of pesticide use are required for restricted-use pesticides. 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.
7.8 IPM Best Management Practices
- Develop a facility-specific, written IPM plan. Available resources for writing an IPM plan include the Golf Course Superintendents Association of America’s IPM information and online tools.
- Select turfgrass cultivars and species recommended for use in areas with similar climate and best suited for the intended use and environmental conditions of the specific site.
- Correct the soil’s physical and chemical properties that may impact turfgrass health and its ability to resist pests.
- Evaluate the potential impact of the timing of cultural practices and nutrient applications on the incidence of pest problems.
- Use a defined pesticide selection process to select the most effective pesticide with the lowest toxicity and least potential for off-target movement.
- Document all IPM-related activities, including non-chemical control methods and pesticide usage.
Monitoring Pests and Recording Information
- 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.
- Assess pest damage when it occurs, noting particular problem areas, such as the edges of fairways, shady areas, or poorly drained areas.
- Document when the damage occurred. Note 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.
Identifying and Understanding Pests
- Identify key pests in the IPM plan.
- Determine the pest’s life cycle and know which life stage to target (e.g. for insect pests, whether it is an egg, larva/nymph, pupa, or adult).
- Identify pests accurately. For diseases, correctly identifying the disease pathogen often involves sending samples to a diagnostic laboratory.
- Establish injury and treatment thresholds levels for key pests and document them in the IPM plan.
- Implement proper cultural, irrigation, and turf management practices to reduce stress and pressure of pest establishment.
- Maintain a proper fertilization schedule to improve turf density and quality and reduce pest populations.
- Make sure your materials, such as topdressing, are pest-free.
- Apply a preventive pesticide to susceptible turfgrass when unacceptable levels of disease are likely to occur.
- Address damage from turfgrass pests such as diseases, insects, nematodes, and animals to prevent density/canopy loss to broadleaf weeds.
- Divert traffic away from areas that are stressed by insects, nematodes, diseases, or weeds.
- When nematode activity is suspected, an assay of soil and turfgrass roots is recommended to determine the extent of the problem.
- Release insect-parasitic nematodes to naturally suppress insect pests such as white grubs.
- Identify areas on the golf course that can be modified to attract natural predators, provide habitat for them, and protect them from pesticide applications.
- Install flowering plants that can provide parasitoids with nectar or sucking insects (aphids, mealybugs, and soft scales) with a honeydew source.
- Avoid applying pesticides to roughs, driving ranges, or other low-use areas to provide a refuge for beneficial organisms.
- Follow a selection process when conventional pesticide use is warranted.
- Follow guidelines and advice provided by the FRAC, HRAC, and IRAC to reduce the likelihood of pesticide resistance.
- Evaluate use of reduced-risk pesticides and biopesticides to treat the problem.
- Follow local permitting requirements.
- Notify the following of when/where an open burn will occur: local fire department, municipality nearest the burn, the county sheriff’s department, and any military, commercial, county, municipal or private airport or landing strip that may be affected by the open burn.
- Make sure the burn area is free of any debris.
- Ensure that the prevailing winds during the burn are away from any town/city or any occupied residence likely to be affected by the smoke to the best extent possible.
- Minimize the amount of dirt in the material being burned to reduce smoldering.
- Conduct open burns between three hours after sunrise and three hours before sunset to allow for smoke dispersion and to avoid air inversions that can trap the smoke at breathing level. Additionally, fuel should not be added outside the timelines listed above.
- Extinguish an open burn completely to ensure smoldering of material does not persist.
- Do not create a traffic hazard on any public road or airport right of way or obscure visibility.
- Use common sense precautions, such as having someone watching the fire until it is extinguished and assuring smoke does not impact residences or impair vehicular travel on highways.
Evaluation and Record Keeping
- After treatment, determine whether the corrective actions reduced or prevented pest populations, were economical, and minimized risks. Record and use this information when making similar decisions in the future.
- Observe and document turf conditions regularly, noting which pests are present, so that informed decisions can be made regarding the damage the pests are causing and what control strategies are necessary.