Unit 4: Turfgrass Cultural Practices
Lesson 5: Integrated Pest Management
Controlling Turfgrass Weeds, Insects, and Diseases
Correct identification of weeds, insects, and diseases is crucial when making a decision about control methods. When considering control methods for turfgrass pests, managers strive to be responsible stewards to the environment and prioritize public health and safety through the use of Integrated Pest Management (IPM) practices. IPM is an effective and environmentally sensitive approach to pest management that relies on a combination of common-sense practices. IPM programs use current, comprehensive information on the life cycles of pests and their interaction with the environment. This information, in combination with available pest control methods, is used to manage pest damage by the most economical means, and with the least possible hazard to people, property, and the environment.
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The goal of IPM in turfgrass is to keep pest populations or damage at a tolerable level so there is no reduction in quality or safety to the turfgrass. To achieve this goal, turfgrass managers follow 4 steps:
Step 1: Set a threshold
The threshold is the point pest populations or environmental conditions indicate pest control action must be taken. It does not mean that if you see one single pest, control is needed. The area needs to be evaluated to determine if the pest population or pest damage warrants control. What is the threshold?
Do you spray immediately when you see a few diseased areas?
Or do you wait until your turf area looks like this?
Turfgrass managers need to decide on the threshold level. The threshold depends on the level of cultural intensity. Some facilities may have a lower tolerance than others. For example, a high end golf course will have a low tolerance for pest infested turf, whereas a low maintenance soccer field will have a higher tolerance for pest infestation.
Step 2: Identify and monitor pests
Earthworms in a turfgrass area
Not all insects, weeds, and diseases require control. Being able to correctly identify a pest allows managers to determine if the pest is a problem and if control measures need to be implemented. Monitoring pests helps managers determine if and at what point corrective measures need to be taken.
If a high population of earthworms are identified in a turfgrass environment, should control measures be taken?
In most cases, earthworms are considered a beneficial organism and methods of control do not need to be implemented.
Should control measures be taken against white grubs?
White grubs in a turfgrass area
Photo: Shaohui Wu
It depends on the threshold level that has been determined for the turfgrass area. Lower maintenance turfgrass areas will have a higher threshold for white grubs and control measures may not be implemented. High maintenance turfgrass areas may have a very low threshold for white grub damage and will need to consider control measures.
Monitoring pests also includes evaluation of past, current, and future weather conditions. Changing weather conditions may eliminate the need for control. For example, high heat and humidity favors the development of some diseases. If thunderstorms and cooler temperatures are in the immediate forecast, managers may be able to hold off on control measures. The onset of cooler temperatures and low humidity may reduce disease incidence and eliminate the need for a chemical application.
Step 3: Prevention
Photo: Victoria Wallace
As the first line of defense, maintenance programs work to incorporate cultural practices that keep pests from becoming a threat. Utilizing cultural practices to achieve the healthiest stand of turfgrass possible is the goal for IPM programs. Mowing, fertilization, irrigation, overseeding, and aeration contribute to a healthy, dense stand of turf. Healthy, actively growing turfgrass can outcompete weed invasion, better withstand insect damage, and recover from disease. Prevention can also mean taking steps to eliminate the possibility for pest infestation. For example, perennial ryegrass is especially susceptible to a disease called gray leaf spot. A manager may choose to plant Kentucky bluegrass to eliminate disease threat.
Photo: Dr. Mike Goatley, Jr.Immediately resorting to chemical applications does not qualify as a preventative measure. Chemicals should only be used as a last resort.
Step 4: Control
When monitoring, identification, and thresholds indicate pest control is required and preventative methods are no longer effective or available, IPM programs evaluate the proper control method. Control methods may be cultural, biological, or chemical.
Cultural Control Methods
Cultural controls are practices that reduce pest establishment, reproduction, dispersal, and survival. One of the most important cultural controls is maintaining a healthy, dense stand of turfgrass. When grass is healthy and actively growing, it can often outcompete weeds, insects, and diseases. Maintaining a healthy stand of turfgrass can be achieved through proper mowing, seeding, fertilization, irrigation, and aeration.
Additional cultural controls include:
Photo: Victoria Wallace
- Planting insect resistant turfgrass varieties or endophyte-enhanced turfgrasses. Endophytes are usually beneficial fungi that live between the cell walls of grass plants. In most instances, fungal endophytes produce alkaloids, which give enhanced resistance to insects and disease. Currently, endophytes occur in tall fescue, fine fescue, and perennial ryegrass.
Photo: Victoria Wallace
- Applying fertilizer and irrigation moderately. Fertilization can help build strong root systems that are more resistant to insect damage. Excessive soil moisture and drought can sometimes increase the severity of insect and disease infestations. Excessive soil moisture promotes the development of disease during the summer months and can also attract egg-laying female insects. Drought conditions are also detrimental in that infested turfgrass will not outgrow pest damage due to the added water stress. Damage can be outgrown if water and nutrients are continually available.
- Conducting aeration, vertical mowing, and topdressing to help control the thatch layer. A thick thatch layer provides habitat for insect infestations.
- Scheduling irrigation to occur early in the day to minimize moisture accumulation on turfgrass leaves. High moisture in the turfgrass environment combined with heat and humidity promotes development of disease. Removing dew from the turfgrass leaves early in the day by mowing can also reduce disease development.
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