Integrated Pest Management for the Turfgrass Manager

By Dr. Gene R. Taylor, Assistant Professor and Extension Turfgrass Specialist

IPM is defined as a multi-disciplinary, ecologically-based pest management system that uses all available methods to keep pests at non-damaging levels while minimizing the effects on man, the environment, and turf. A sound IPM program is based on the acceptance and tolerance of pests at damage levels which do not significantly reduce the quality of the turf. Once pest damage reaches a specific predefined level of infestation or damage, specific control measures may be taken, using pesticides only when control of the pests cannot be obtained with other non-chemical methods. It is this reduced reliance on pesticides which is an important factor in managing golf courses, parks, athletic fields, and landscapes for water quality.

A sound IPM program will include:

• A written copy of the program defining all aspects of pest management

• Within the written document, a set of acceptable pest-tolerance thresholds (weeds allowed in the rough, or number of white grubs per square foot of turf, etc.)

• Non-chemical control measures to be taken for specific pest infestations

• Cultural practices which may help reduce the impact of some pests (aerification to reduce compaction - thus reducing goosegrass populations, planting of insect and disease resistant varieties of turfgrasses, sterilization of topdressing soils to keep weed seeds off of greens and tees, and other sanitary practices)

• Scout for pests frequently

• Keep accurate records of pest infestation found, actions taken, and results

The written copy of the IPM program is very important in that it requires the turfgrass manager to determine and write out all of the factors in his/her program. The grounds manager should use the writing of the program to gather information from the greens committee, manager, and coaches as to what they expect from him/her in terms of proper pest management. The greens committee and club manager may help in determining pest threshold levels that are acceptable on the site. Once in written form, the plan will be a source of information and an educational tool for the grounds manager and staff about the proper management of pests in the landscape.

Thresholds are pre-set levels of acceptable pest damage or infestation which will determine when control measures must be taken. Thresholds will change from site to site; for example a few broadleaf weeds may be acceptable in a fairway or the rough but not on a green. Thresholds will also change from pest to pest; for example, a small outbreak of dollar spot on a green may be allowed without much concern or any control measures being taken, but an outbreak of pythium blight on a green would require instant applications of control measures.

Non-chemical control methods may include the use of mechanical or attractant traps for insects, the release of beneficial predatory insects or nematodes, and the use of biological insecticides such as Bacillus popilliae for control of white grubs. The planting of turfgrasses which are resistant to some pests is an important way to reduce the need for pesticides. There are several cultivars of tall fescue and perennial ryegrass on the market which are infected with an endophyte fungi, which makes them resistant to some surface-feeding insects. Unfortunately, there are a limited number of biological control methods available for turfgrass, and the ones available may be slow in control, and the golf course may be forced to accept some pest damage even with their use.

The cultural practices a grounds manager uses can significantly impact pest infestation. The simplest way to keep pest damage and infestation to a minimum is to keep the turf as healthy and stress-free as possible by effective use of basic cultural practices. The grounds manager must have a thorough knowledge of all of the turfgrasses on the site to effectively manage the turf. Mowing of the turf at a height which is too low may cause the grass to be under stress, which in turn makes the turf more susceptible to insect and disease infestation. A dense turf is one of the best controls for reducing weed infestation because it simply out-competes the weed. Aerification of compacted soils will help reduce populations of certain weeds, like goosegrass and spurge, and increase the rooting capability of the turf. The use of fans on greens which have poor natural air flow may reduce the stress on bentgrass turf by increasing transpirational cooling and drying out of wet soils; this will then reduce thinning of the turf, and reduce the chance of disease infestation.

There should be a written scouting plan for insects in the IPM program. Since most grounds managers are out on their site several times a day, they are able to look for problems constantly. But there are some problems the grounds manager may be able to predict, such as germination of crabgrass when soil temperatures reach 60 degrees F, or brown patch infections when daily temperatures and relative humidity are high. These predictable occurrences should be included in the IPM program so that other members of the staff will know when to look for them. The grounds manager should take the time to train his staff to look for potential pest problems.

Once a pest infestation is observed, the grounds manager should first record the pest type, infestation level, and location, and then determine if it is at a threshold level that requires control measures. If so, record the control measures taken and the results. It is important that the grounds manager keep these records, because they may help in predicting future pest problems and the best control measures to take. Mapping of pest populations may help the grounds manager determine problem areas, and reduce the need for blanket pesticide applications. If the grounds manager knows from previous years that crabgrass and goosegrass were problems on only certain areas of the playing field, he/she may elect to apply preemergent herbicides only to those areas. This will reduce the amount of pesticide required, the cost of application, and the chance of water contamination from the pesticide. Frequent outbreaks of pests on a given area may also indicate to the grounds manager that there are other possible problems with the turf and its environment, such as low soil pH, nutrient deficiencies, soil compaction, poor drainage, restricted airflow, or damaged or improperly-working irrigation heads.