Monthly pesticide reports from SF Recreation and Park Department, as compiled by Rupa Bose. (Courtesy Sally Stephens)

Why spray any toxic herbicides in city parks?

San Francisco prides itself on leading the way with the environment. But when it comes to using toxic herbicides in city parks, we’ve fallen behind other cities. While they implement outright bans, we continue to accept – and even encourage — the use of herbicides as long as they’re used to kill non-native plants. And, after a brief decline, that usage is once again on the rise.
In 1996, San Francisco passed an ordinance to “eliminate or reduce” the use of pesticides (including herbicides) on city property. But less than a year later, The City amended the ordinance to allow pesticide use if a city department could show a “compelling need” for it.

The Recreation and Park Department has used that loophole to justify repeated spraying of toxic herbicides in “natural areas” in city parks. These areas, nearly a quarter of all city parkland, are where the department hopes to recreate the landscape that was here in the 1700s, before European colonists first arrived.

But “native plants” are no longer well suited to today’s changing environment. Non-natives, however, do well. So, Rec and Park tries to kill the non-natives by spraying some of the most toxic herbicides available.

Consider Garlon, with the active ingredient triclopyr. The herbicide has been linked to birth defects and kidney and liver damage in rats and dogs. It alters soil biology and persists in dead vegetation for up to two years. Rec and Park uses Garlon to get rid of oxalis, a non-native plant with pretty yellow flowers that native plant advocates consider extremely invasive. But the herbicide is not particularly effective.

Oxalis spreads by sending out roots and forming little bulbils (like tiny potatoes) underground. While Garlon kills the visible plant above ground, it doesn’t touch the bulbils. So, the plant regrows. It therefore requires many, many applications of Garlon, year after year, to finally exhaust the bulbils and kill the plant.

Rupa Bose submits a sunshine request to The City every month for pesticide usage reports. Her most recent data compilation shows that, after a brief period of decline, Rec and Park usage of herbicides has increased sharply since 2016. Nearly all was used in natural areas.

In the first half of 2018, for example, Rec and Park has already sprayed more Garlon than it used in the entire 12 months of any of the last four years.

They’ve also sharply increased the amount of Roundup used. Glyphosate, the active ingredient in Roundup, was determined by the World Health Organization to be “probably carcinogenic.” Monsanto, maker of Roundup, is currently being sued in court by a gardener who claims the herbicide caused his cancer.

Protecting biodiversity is often used to justify herbicide use. But all plants contribute to biodiversity, not just native plants.

Department of the Environment staff are supposed to monitor herbicide use by city departments. Yet they seemingly rubberstamp Rec and Park’s requests to use herbicides to kill non-native plants.

Last year, for example, Environment staff allowed Rec and Park to spray Garlon on an official trail on Mount Davidson despite city requirements that no spraying be done within 15 feet of a trail. People walking in the park were potentially exposed to a nasty herbicide to keep a non-native plant from crossing the path.

Bose once asked Environment staff what happens if a department violates the herbicide rules. She was told, “They’d be embarrassed.” Clearly, there’s no real penalty for misusing pesticides.

In the meantime, other cities, including Arcata and Fairfax, have banned all pesticide use on city property. The Marin Municipal Water District hasn’t used herbicides on its lands since 2005. UCSF doesn’t spray herbicides on Mount Sutro.

Arcata has even managed to maintain a baseball field used by the semi-pro Humboldt Crabs in competition quality without the use of herbicides. It meant thinking outside the box — e.g., designing tarps to cover the infield dirt to retard weed growth between games — but it has worked.

Yet San Francisco remains trapped in the old-fashioned, just-spray-more-herbicides approach to land management. I don’t think it’s too much to ask the Department of the Environment — the agency that’s supposed to protect us from poisons– to keep our city parks free of toxic herbicides.

Sally Stephens is an animal, park and neighborhood activist who lives in the West of Twin Peaks area.

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