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The City of Portland, Oregon

Portland Parks & Recreation

Healthy Parks, Healthy Portland

Phone: 503-823-7529

1120 SW Fifth Avenue, Portland, OR 97204

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Natural and Synthetic Pesticides

'Pesticide' is a general term for any substance used to control pests. Pesticides can be insecticides to control insects, herbicides to control weeds, rodenticides to control rodents, and other categories. They can be made from natural sources, such as pyrethrin insecticide extracted from certain chrysanthemum plants. Another example is azadirachtin, an extract from the neem tree. Pesticides can also be made synthetically, as in pyrethroids, which control insects as pyrethrins do. It is important to know that the vast majority of pest management practices in parks never involve the use of pesticides. If pesticides are used, they are selected and applied carefully, usually to control unwanted vegetation in certain areas and to control non-native invasive plants when restoring wildlife habitat in our natural areas. Some areas such as golf courses and rose gardens have special requirements such as the management of certain plant diseases or insects. These areas may need to receive different kinds of pest management methods and materials than a typical park would.

Before any pesticide is approved for use in our parks, a thorough process of research, evaluation, and formal approval occurs. Pesticide use that would pose any undue risk to park visitors or park staff does not take place. Any concerns about potential environmental effects are carefully investigated and satisfied before a pesticide is added to an approved list. Scientific studies, EPA registration documents, information from university environmental toxicologists, regulatory decisions and assessment documents from other sources are just some of the resources we investigate when determining whether a pesticide makes sense for use within our program.