2018 Herbicides in San Francisco: NRD Use Rises (Again)

For many years now, we have been obtaining and compiling monthly pesticide use reports from San Francisco Recreation and Parks Department (SFRPD).  This is our report for 2018.

Our analysis omits Harding Park, which is under contract to the PGA and must be tournament-ready at all times. We do include other golf courses, including the nearly pesticide-free Sharp Park in Pacifica (of which more later).

We analyze the data separately for the Natural Resources Department (NRD, formerly the Natural Areas Program or NAP). This is the entity that is trying to bring “native” plants to more than a thousand acres of our parks,  cuts down trees and restrict access to people and their pets. (For details, see this LINK.) It  uses toxic herbicides against non-native plants it considers invasive, currently nearly 50 species.

The NRD was the largest single user of herbicides within SFRPD. In fact, it used significantly more herbicides than the rest of SFRPD put together, including all the golf courses except Harding. SFRPD applied herbicides 223 times, of which 175 176 were in “Natural Areas” (this includes PUC areas managed in the same way – i.e. use of toxic herbicides against plants they dislike).

[Edited to Add: We have changed the chart above to correct the data.]



SFRPD (excluding Harding, and excluding NRD) continued to reduce its use of herbicides. Which is good news. They’ve also almost stopped using Tier I products. (SF Department of the Environment – SFEnvironment – groups those pesticides that the city permits to be used on city properties into three Tiers. Tier III is least hazardous; Tier II is More Hazardous; and Tier I is Most Hazardous.) The only usage in 2018 was Roundup Custom on a tree stump in Duboce.

There are some disturbing developments; the drop was a mere 6%, compared to a 34% fall in 2017, a 56% decline in 2016, and 30% in 2015.


NRD dropped its pesticide usage sharply in 2014, and continued the decline through 2016. But in the last two years it started climbing again, and it now is at the highest it’s been in five years (see the graph below).

They’ve added another Tier II pesticide to their arsenal: Axxe, which they tried on oxalis. On the whole, this herbicide is probably not as bad as some others; it has an OMRI listing for organic use. They also used Clearcast on Lake Merced against waterplants.


Honeybee in oxalis flower

The really bad news, though, is the increase in the use of Garlon (triclopyr), the most toxic herbicide that SFEnvironment permits. It’s what they use in their perennial, pointless, and apparently escalating war on oxalis.

The increase is clearer in the graph below. (The orange columns are Garlon.) NRD increased its use of Garlon by about 90% from 2017, and it’s the highest it has been in the last five years.

Oxalis is a beneficial plant: It produces copious amounts of nectar, which is food for bees, butterflies, and other pollinators. Its bulbs provide food for (native!) pocket gophers and some birds. Its brilliant yellow flowers bloom early in spring, before most other flowers. Kids like to chew on its sour stems (it’s also called sourgrass) and even adults have fond memories of this plant. Other than nativist purists, most people love it for its beauty – it’s a sign of spring in San Francisco.


Last year, SFRPD declared war on Cape Marigold, arctotheca. This is a ground-cover plant that’s attractive to butterflies, bees, and other pollinators, but is considered “invasive” – i.e., successful in the urban environment we currently have in San Francisco. In 2018, this attempt resulted in 21 applications of herbicides (of a total of 223), including the first time since August 2010 that pesticides have been used in Sharp Park, habitat for the endangered red-legged frog and the California garter snake.

Nearly all applications were of Milestone VM (aminopyralid) but one was of Sapphire (penoxsulam) – hitherto restricted to golf-courses ONLY in preparation for tournaments. On this occasion, it was being used on the St Mary’s playing field.

Cape Marigold (also called the Plain Treasure Flower) has bright yellow flowers that look like daisies. It’s in the aster family, has a fairly long flowering period, and also provides food for butterflies and bees.


As we said in our half-year report, three new herbicides have been added to the list permissible for use in San Francisco: Axxe (which we mentioned above), Lifeline, and Clearcast.

The list of target species is also growing, and we’ve now counted 47 types of plants that are being sprayed with herbicides. The 2018 newcomers to the list are a couple of succulents: Aeonium, and crassula. Also added to the list is “Cat’s Ear,” an edible plant resembling dandelions and widespread enough that if it’s a target it would provide an excuse for considerable pesticide use. There’s another plant listed as Cape vertigo (sometimes the form is unclear!), which may be an ornamental grass.

We slightly modify our conclusions from our Half-Year report in July: While we are glad that SFRPD has moved to reduce herbicide use (at least in non-Natural areas), we’re disappointed that it continues to consider pesticides a viable strategy. We’re also disappointed at the opening of more battle-fronts against plants, which will inevitably push for more pesticide usage. We’re disappointed at the rising usage by the NRD.

We would like to see SF Environment take the leadership in moving San Francisco to a policy of No Pesticides in our Parks and Watersheds.