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Integrated Pest Management

What is Integrated Pest Management?
Integrated Pest Management or IPM is an approach that uses a variety of strategies to prevent and control pest problems. IPM employs physical, mechanical, cultural, biological, and evaluation processes to minimize damage to landscape areas. Chemical products are used as a last resort and the least toxic chemicals are preferred.

Why do the parks look so good?
Renton parks have been master planned and developed which has resulted in well organized facilities and grounds. Park maintenance staff keep parks clean and safe for public use. Park staff regularly mow, edge, weed, use pest control practices, monitor park conditions, and provide immediate response to remedy problem situations.

Maintenance efforts are based upon three quality levels of service. Intensively managed areas, also known as Level 1 parks, receive a higher level of maintenance because they are used regularly by the public. Liberty Park and Gene Coulon Park are two examples of Level 1 locations. Level 2 parks are used less intensively.  As a result, there is less effort to rid these parks of weeds and other pests. Level 2 locations include Maplewood Park and Kiwanis Park. Level 3 parks are primarily natural areas and receive a much lower level of maintenance.

What are buffer zones?
Buffer zones are strips of vegetation of varying widths and lengths between a source of water and a managed area. Buffer zones are excellent filters for water runoff and help to cleanse surface water before it moves into rivers and lakes. The City of Renton maintains buffer zones of varying widths near rivers and lakes. It typically prefers a 60-foot buffer.

What alternatives to chemical control of pests does the City of Renton use?
The City of Renton Parks considers all alternatives to managing pests. Power sweeping trails, hand pulling weeds, flame-torching weeds, using weed barrier fabrics, and hand picking insects are some of the methods used to control pests.

During 2002, City staff and volunteers worked 20,000 man-hours to hand-weed shrub and flower beds. Following hand-weeding, beds are treated with a two inch coat of finely shredded bark mulch which reduces subsequent weed growth. A flame torch is used along sidewalks to remove weeds growing through cracks. The Parks Division utilizes its best management practices and has tested different weed barrier fabrics to determine which are the most effective in controlling weeds. Weed barrier fabrics are used mainly during trail construction projects. Staff handpicks caterpillars from vegetation when they become concentrated and pose a threat to trees and shrubs. Using biological control, the City has used ladybird beetles that feed on tree aphids.

When and how does the City of Renton use pesticides?
Herbicides are used on all actively managed park and trail areas. Of the 945 acres of parkland, 245 acres are actively managed. Herbicides are used infrequently on shrub beds and even less frequently on turf areas. When spraying occurs, areas are posted with signs. A systemic insecticide (taken up by tree roots instead of sprayed) is used to control aphids on downtown street trees.

Most herbicide applications are applied as a spot spray. This means when the population of weeds approaches the tolerance level for the area being managed, the weed is treated. Spot spraying lowers the volume of applications and minimizes environmental impacts.

What areas are pesticide free?
The City of Renton maintains 700 acres that are pesticide free all of the time. These are natural and open space areas. Examples of locations include the Cedar River Natural Zone, Honey Creek, May Creek, and the Black River Riparian Forest.

What practices does the City use to maintain its parks, trails, and open spaces today?
Integrated Pest Management is the strategy used to maintain parks, trails, and open spaces. Crews working in parks monitor conditions daily. When pest problems increase beyond a tolerable level, they employ several strategies to reduce specific problems. Quality Level 1 areas have a lower tolerance for pests. There is a higher tolerance for pests in Levels 2 and 3.

Some of the practices used to reduce pest problems include:

  • Plant appropriate vegetation and maintain healthy groundcovers, shrubs, and trees.
  • Conduct soil tests and modify soil conditions with compost, mulch, and fertilizers to promote healthier plants.
  • Provide adequate moisture.
  • Cultivate plants using topdressing, soil aeration, and soil slicing equipment.
  • Proper pruning of shrubs and trees to increase air circulation and remove dead and diseased branches.
  • Maintain proper turf heights and use grass-cycling (grass blades left on turf).
  • Use of bird repellent sound equipment and dogs to chase nuisance birds.
  • Bark mulch shrub areas and trees. Mulch conserves moisture, reduces weeds, and protects vegetation.
  • Physically remove pests using hand labor, implements, and power equipment.

The City follows local, state, and federal laws and regulations with respect to maintenance activities in general and to chemicals specifically. All park employees are licensed pesticide applicators through the Washington State Department of Agriculture and receive 40 hours of continuing education, mostly in IPM strategies, to maintain licenses. Re-testing is performed every three years.

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