Seattle University, WA Integrated Pest Management Policy

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Seattle University, WA, US

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Type: Policy

Status: Adopted in 1979

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Seattle University differs from most other campuses by rejecting the notion that pesticide application is a viable last resort. A shift to sustainable landscape practices began in 1979 with the adoption of an Integrated Pest Management (IPM) program. The Grounds Department has successfully and beautifully maintained the 48 acres since 1986 without the use of pesticides.

Four components in an IPM program:

Mechanical - pests are physically removed or disrupted using various traps and tools

Cultural - planting plants of different species that are naturally disease or insect resistant

Biological - release of beneficial insects that prey on harmful pests

Chemical - use of natural compounds (i.e. insecticidal soaps, compost tea, vinegar and citric acid)

Responsible plant selection. Plants are carefully chosen that need little water, are well suited to the Northwest climate, resist insect and disease infestation, and are not invasive species that out-compete native species. Selecting combinations of plants that meet this criteria and are also aesthetically pleasing, low maintenance, affordable, and contribute to the creation of wildlife habitat is a subjective and sometimes difficult process that the gardeners work hard to achieve.

Turf mix. A traditional lawn care program calls for excessive use of synthetic fertilizers, pesticides and water to maintain a monochrome green carpet year round. A sustainable lawn care program uses a custom mix of grasses adapted to the local climate. At SU, a 25,000 square foot lawn was seeded with New Zealand white clover and tall fescue grass. An occasional clover flower escapes the mower to help people regain an appreciation for a lawn that functions like a meadow and blooms with petite flowers year round. The nitrogen fixing clover ensures the turf will never need fertilizer, is wear resistant and drought tolerant.

Weed suppression and control. Aggressive, thick ground covers are densely planted to out-compete and hide weeds, a time and money saving solution to weed control. It takes about three years for a new landscaping project to become weed-free. These areas are maintained by hand labor during the transition time but afterwards are almost maintenance-free. Installing the right mix of groundcovers can cost thousands of dollars up front; however the plants pay for themselves within a year after the hand-weeding ends.

Sheet mulching. A layer of cardboard or several layers of wet newspaper are put on top of bare soil or scalped turf prior. This layer beneath the wood chips allows moisture and nutrients to pass through and provides additional, temporary weed suppression until it breaks down into the soil.

Wood chip mulch. Branches from pruning and unwanted trees are put into a chipper to create wood chips. A four to six inch layer of wood chips suppresses most emerging weed seeds. The “soil to chip interface,” where many dormant weed seeds potentially reside, is depleted of available nitrogen during the breakdown of the high carbon content of the wood chips, further helping to suppress weeds. Wood chips are comprised of several parts of the tree: leaves, cones, flowers, sap, cork, stems, bark, lignin, pith and heartwood. This provides soil organisms a richly varied food source that comes closer to recreating the forest floor. In turn, these soil organisms aid the plants in the uptake of water and nutrients.

Nutrient cycling. In many landscapes, nutrients in fallen leaves, flowers and cones are raked up and disposed of off-site. This interruption of the nutrient cycle starves soil organisms of a critical food source. As nutrients synthesize, soil dwelling organisms, such as bacteria, fungi, protozoa, and arthropod populations decrease, and the plant’s need for another source of nutrition increases. Without these organisms, which aid in the uptake of nutrients, a cycle of dependency begins and the weakened plants become more susceptible to the risk of disease or insect infestation. At SU, the nutrients in fallen leaves are recycled by mowing leaves where they fall on lawn or blown back into beds and a thin layer of wood chips are added to hold them in place. Where this is not possible, leaves are collected for use as a carbon source in the compost operation.

Grasscycling. Grass clippings are left on the lawn to decompose, which eliminates waste, reduces labor, recycles the nutrients in the grass clippings and reduces the need for fertilizer. The decomposing grass clippings provide organic matter and nutrients which feed soil dwelling organisms who process the nutrients into a food source for the lawn, reducing fertilizer needs.

Mychorryzia fungi. This group of fungus forms a symbiotic relation with the root system of plants. It aids in the uptake of nutrients and can expand the root system more than ten times creating more drought tolerance. Mychorryzia is present in undisturbed natural soils but is destroyed during tilling, grading, and excavation, and is not present in compacted soils. Products with mychorryzia spores are added to new plant installations to help re-inoculate the depleted topsoil brought in for new construction, trees under stress adjacent to construction projects, and beneath new sod installations.

Compost topdressing. High quality compost is utilized in poor soils that are struggling such as fill soil. Imported, disturbed soil does not have the complex diverse soil ecosystem that is self supporting. It lacks the built up of layers of fresh organic matter, decomposing organic matter, and humus that can support the organisms that form a symbiotic relationship with the plant world. Often, project specifications require slow release fertilizer to feed the plant throughout its first year. This is like treating the symptom instead of the disease. The University’s on-site compost facility produces impeccable quality compost capable of re-inoculating sterile imported topsoil and helps it reach a sustainable level. The compost provides many of these microscopic organisms as well as a food source. Some plants can sense the organisms are present and begin to exude up to 50% of their stored proteins which feed the organisms that in turn feed the plant and the cycle continues.

Compost tea application. A compost tea brewer was purchased in 1999. The brewer is a 30-gallon centrifuge that circulates aerated water through high quality compost. Different recipes are used to target different problems that occur. The tea is sprayed on disease prone plants and used as a soil drench around trees, shrubs, and turf that are struggling. Disease resistance systemically spreads throughout a plant that has had compost applied. The gardeners have had success in treating black spot on roses, powdery mildew on rhododendrons, and in improving the drainage in soggy lawns.

Beneficial insect release. In 2003, over 100,000 microscopic parasitic wasps, a beneficial insect, were released to control a pest decimating cherry trees. In 2004, over 3,000 mating green lace wings were released to control aphids.

Sand-based athletic fields. The turf on Championship and Logan fields grows in pure sand because sand provides a well-draining firm surface even when the rain is pouring down. However, it is unnatural for grass to grow in sand so it needs a lot of life support. Typically, most organizations use fungicides, herbicides and synthetic fertilizer. In 2006, the sand-based athletic fields switched from synthetic fertilizer to a maintenance regime that includes applications of compost tea, mycorrhizal fungi spores and organic fertilizer to improve the root growing environment. The tea has good fungi and bacteria that attach themselves to the root zone and fix nitrogen. Grass clippings are also left on the field to break down and add nutrients to the soil. The first year saw a 26% reduction in water usage and healthier turf. The athletic coaches were thrilled with the condition of the fields.