Pesticides ‘Throughout the Park’

Recently, one of our readers sent us this picture of a pesticide notice from McLaren Park. It was breathtaking in its breadth, also rather confusing.

  • They were applying Aquamaster (this is glyphosate, the same chemical used in Roundup) for three different plants.
  • They had an initial window of 8 days, then added another 5-day window.
  • They were applying it “throughout the park.”
  • It would be safe to re-enter, it noted, “When Dry – at least a few hours after spray.”
  • And then, they did some spraying, there was a postponement of part of the spraying, and they did some more spraying on a different date.


We appreciate the efforts SF RPD is making to properly notify park-users… but look at this notice from a park-goer’s point of view. Then the following questions arise:

1.  When did they spray?

According to this notice, they did the fennel on April 24th. That part of the notice said “Before 10 a.m.” –  so presumably that’s when. Some time before 10 a.m. that morning. The second part, the extension of the dates, didn’t have any times on it. They apparently sprayed the fescue grass on May 4th. When exactly? We don’t know.

2. When will it be safe to go back in?  What’s “a few hours”?

No member of the public really wants to go among sprayed plants to check if they’re still wet, and especially they don’t want kids or pets doing it.  Lisa Wayne of Natural Areas Program has said that the people doing the spraying stay on-site until the pesticide is dry. Do they really remain in the vicinity for a few hours?

We also note they’re using vegetable oil as an adjuvant. As far as we know, vegetable oil takes a long time to dry, and remains sticky for hours or days.

If this is not true, we’d appreciate a clarification and some practical data.

3.  Where did they spray?

Nearly all of McLaren Park that isn’t actually dedicated to a specific activity like golf or playgrounds is Natural Area. (See the map; the yellow areas are NAP land.) Since the sign says “Throughout the Park,” it could be pretty much anywhere.

Not everyone can even identify fennel or bindweed or fescue, so they wouldn’t have any idea which plants to avoid – and besides, these are plants that mingle with others in mixed groups.

4.  What happens when people cannot read English?

Some of our parks are in majority Spanish-speaking neighborhoods. Shouldn’t the pesticide signs have some kind of graphic so people know to stay away and when it’s safe to re-enter?

If a park-goer with kids and dogs took this notice seriously – assuming they saw it, since some visitors on the same day did not – they would have to presume that they should stay out of the park altogether for at least 2-4 days.

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