Garlon v. Oxalis – in 10 Easy Slides

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Mt Davidson: Toxic Garlon, Felled Trees

On a recent trip to Mount Davidson, a visitor saw that Garlon had been sprayed on oxalis.

The Natural Resources Department (NRD, formerly Natural Areas Program) is the most frequent user of pesticides in San Francisco Recreation and Parks Department (SFRPD).  It applied herbicides on Mt Davidson 8 times in 2016. Other SFRPD units have all but stopped using herbicides.

Notice of Garlon 4 Ultra on Oxalis on Mt Davidson, San Francisco CA

Garlon 4 Ultra on Oxalis on Mt Davidson, San Francisco CA

The Natural Resource Department (NRD, formerly Natural Areas Program or NAP), observed the SF Department of the Environment guideline to use blue dye with its herbicides (so people can see and avoid those areas).

Blue dye indicates Garlon 4 Ultra on Mt Davidson Jan 2017

Blue dye indicates Garlon 4 Ultra on Mt Davidson Jan 2017

Unfortunately, they flouted the SF Environment guideline that says there should be no herbicides used within 15 feet of a trail. “Blue dye is right next to and on the trails…” said the visitor.

(Edited to Add: We subsequently learned that SFRPD got a special exemption to permit them to spray on the trail, and they were supposed to have blocked the trail to visitors.)

Here’s a picture of blue dye on the trail.

Blue dye shows Garlon on the path on Mt Davidson, Jan 2017

Blue dye shows Garlon on the path on Mt Davidson, Jan 2017

Garlon by the trail on Mt Davidson, San Francisco, Jan 2017

Garlon by the trail on Mt Davidson, San Francisco, Jan 2017

GARLON IS VERY TOXIC

The SF Department of the Environment (SF Environment), which is responsible for the Integrated Pest Management guidelines, lists Garlon 4 Ultra as a Tier I chemical, Most Hazardous. Ever since we started following this issue, it’s been on the list with a bold, capitalized statement: HIGH PRIORITY TO FIND AN ALTERNATIVE.

Garlon is also supposed to be twenty times as toxic to women as to men. (See page 28 of this California Native Plant Society Presentation which discusses best management practices in herbicide use: Law_Johnson 2014 presentation toxicity )

An article on SaveSutro.com, based on a detailed study by the Marin Municipal Water Department, describes some of the issues with Garlon:

  • Garlon “causes severe birth defects in rats at relatively low levels of exposure.” Baby rats were born with brains outside their skulls, or no eyelids. Exposed adult females rats also had more failed pregnancies.
  •   Rat and dog studies showed damage to the kidneys, the liver, and the blood.
  •   About 1-2% of Garlon falling on human skin is absorbed within a day. For rodents, its absorbed twelve times as fast. It’s unclear what happens to predators such as hawks that eat the affected rodents.
  • Dogs  may be particularly vulnerable; their kidneys may not be able to handle Garlon as well as rats or humans.  Dow Chemical objected when the Environmental Protection agency noted decreased red-dye excretion as an adverse effect, so now it’s just listed as an “effect.”
  •  It very probably alters soil biology. “Garlon 4 can inhibit growth in the mycorrhizal fungi…” ( soil funguses that help plant nutrition.)
  •  It’s particularly dangerous to aquatic creatures: fish (particularly salmon); invertebrates; and aquatic plants.
  •  Garlon can persist in dead vegetation for up to two years.

parent and child with oxalisThis highly toxic chemical is used by NRD against oxalis during its flowering season – in winter and spring. On Mount Davidson, they used it in February  and December 2016 as well.

It doesn’t make logical sense. Here’s our article on Five reasons it’s okay to love oxalis and stop poisoning it.

TREES BEING FELLED

Meanwhile, another visitor sent us a series of pictures showing trees being felled at the southwest end of the forest.

tree-noticed-to-be-removed-mt-davidson-jan-2017 tree-x-ed-out-jan-mt-davidson-2017 former-trees-mt-davidson-jan-2017.

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San Francisco RPD Map of Responsibility Areas for Pesticides (and Unrecorded Spraying)

If you’ve every wondered – as we have – which section a particular playground or park falls under, this map will help. This also determines who within San Francisco Recreation and Parks Department (SFRPD) is responsible for pesticide use in that area. The black stars represent the areas under the Natural Areas Program (NAP). As you see, they’re dotted throughout the city.

Click here for the full-size (readable!) PDF map: PSA & OS Map

sfrpd responsibility map

TOXIC GARLON FOR MEXICAN BERMUDA BUTTERCUPS

Honeybee in oxalis flower

Honeybee in oxalis flower

In other, somewhat related news: We received the pesticide usage reports for January 2016. The Natural Areas Program was the only section using herbicides in January,  all of it Garlon 4 Ultra against oxalis. SFRPD is convinced that oxalis is a Bad Thing. We’re not. See: Five Reasons it’s okay to love oxalis and stop poisoning it.) Neither are others – here’s an article by a San Francisco mother of two young children: Why this City Spends Millions of Dollars to Eradicate Wildflowers.

THE UNRECORDED SPRAYING ON MOUNT DAVIDSON

But remember this video, showing Garlon spraying on Mount Davidson on January 28th, 2016? (It’s a Natural Area.)

Video of Mt Davidson Garlon 4 Ultra spraying on Jan 28 2016

(If you don’t recall seeing it – it’s only a minute and a half.)

That wasn’t included in the usage report. No mention of Mount Davidson at all. The report only mentioned Garlon use on Bayview Hill, Corona Heights, Twin Peaks, and McLaren’s Geneva meadow.

Which of course leads to the question, what else might be missing from the pesticide usage reports?

San Francisco Herbicides 2015: Why Better Isn’t Good Enough

SF Natural Areas Pesticide by Active Ingredient 2008-2015 sm

NAP’s pesticide usage is down again in 2015

We have some nearly good news. After years of increasing pesticide until 2014, the 2015 data shows Natural Areas Program (NAP) again used less herbicides than in the year before – though they applied it more often. The volume of herbicide used was the smallest amount since 2010, but the number of applications the highest since 2008 (the earliest data we have).

So why isn’t this good enough?

  • The main reason is the growing consensus that herbicides are more toxic than the manufacturers claim. Roundup (glyphosate), long regarded as a “safe” pesticide (though not by us – we wrote about the worrisome scientific data HERE and HERE) has been declared a probable carcinogen. Herbicides don’t have a place in our parks where they could impact people – especially those who have reasons to worry about their toxic load – children, who are more sensitive because of their size and fast growth, and pets. People just don’t want any herbicides in our parks, especially in “Natural Areas.”
  • SF Natural Areas Program Number of pesticide applicns 2008-2015 sm

    But the number of applications is up.

    The second is that though NAP has reduced the amount of herbicides they use, they have considerably increased the number of applications. This means that park-goers have a higher probability of encountering pesticide use.

  • Some of these pesticides remain in the soil and environment for months, even years, after application. Imazapyr’s breakdown product is a neurotoxin. Many of the Natural Areas are on high ground, or in watersheds, and poisons applied there can spread unpredictably.
  • NAP used a dispropotionately large amount of the most toxic herbicides compared with all of SF Recreation and Parks Department (SFRPD):
    • 35% of the Roundup (glyphosate);
    • 80% of the Garlon (triclopyr) and
    • nearly 100% of the Stalker (imazapyr) and Milestone (aminopyralid).

GARLON USAGE: TOXIC AND UNNECESSARY

A case in point is Garlon (triclopyr). This is one of the most toxic herbicides permitted on city-owned properties, with a Tier I (Most Hazardous) rating.

Photo credit: Badjonni (Creative Commons - Flickr)

Photo credit: Badjonni (Creative Commons – Flickr)

NAP is the most regular user of Garlon, mainly to poison yellow oxalis.  In 2015, it accounted for 80% of the Garlon used by SFRPD.They are trying to reduce usage with a new surfactant (the stuff used to dilute the herbicide and let it spread better), CMR Silicone Surfactant. We are unsure whether this is an improvement but will research it further. The Label is here: Cmr_Silicone_Surfactant_(0198050402)_Label

If NAP stopped trying to poison oxalis each spring, Garlon could be removed from the approved list of pesticides. Instead, they used Garlon five times in December, on Twin Peaks, Glen Canyon, Mount Davidson, and McLaren Park. These are places where children and pets could easily encounter the herbicide.

coyote pouncing in oxalis field - copyright Janet Kessler

There’s no need to battle oxalis. It’s beloved by children, attractive to bees and butterflies, useful to other wildlife in the food chain, and a valuable plant that improves the soil for grasses. Moreover, it disappears after its flowering period is over. There is no evidence that it adversely affects other plants in what is essentially a non-native grassland.

ROUNDUP, THE PROBABLE CARCINOGEN

Roundup is the most commonly used pesticide in our parks, and NAP uses a disproportionate amount. It applied Roundup over 70 times in 2015, and the volume used was more than in 2014. We would have expected that after the World Health Organization finding, NAP would stop using this herbicide. It appears not.

The problem is that NAP targets a lot of plant species it considers invasive – at the last count, around three dozen different species. Unless it changes its objectives, it will always need herbicides – Roundup, Stalker/ Polaris, Milestone VM, Garlon 4 Ultra. If it reduces one, there’s a temptation to increase another.

GETTING RID OF HERBICIDES IN NATURAL AREAS

San Francisco can get rid of herbicides in natural areas. It will mean a change in the mindset of land managers. Non-native plants are valuable in wild places for their ecological benefits – carbon capture, wildlife habitat and food, soil enrichment and erosion prevention among others. If we must create native plant gardens, they should be small enough that they can be managed by manual gardening. Though we have issues with what UCSF is doing in Sutro Forest, in one matter they have a clear win: No pesticides have been used there since 2008, and UCSF have committed not to use any herbicides in Sutro Forest. That includes the native plant garden on the summit.

SFRPD REDUCES HERBICIDE USAGE IN 2015

SFRPD Pesticides (ex Harding and NAP) 2013-15SFRPD reduced its herbicide usage in 2015 as well. The numbers for 2014 were exceptionally high because of large amounts of Tier I pesticides used in the Kezar Stadium renovation, and mistakenly in Gleneagles Golf Course. Without those two factors, usage would have declined in 2014 and been nearly flat in 2015.

A word about Greenmatch and Avenger. These are based on lemongrass oil, or what is called a “botanical.” It’s actually considered acceptable for organic gardening. However, it’s classified as Tier II because it can cause allergic reactions in its undiluted form.

KEZAR STADIUM TIER I USE CONTINUES

The renovation of Kezar Stadium has used a lot of Tier I herbicide.

  • In November and December 2014, they used 208 fluid ounces of Drive XLR8 for turf renovation. This was a one-off Tier I pesticide use, and may have been associated with bird deaths in the area.
  • In February 2015, they used 320 fluid ounces of Fiesta, also classified as Tier I, followed by 24 ounces of Aquamaster (which was subsequently classified as Tier I).
  • In June 2015, they used 16 ounces of Turflon (triclopyr), also Tier I and one of the few times any SFRPD department but NAP used triclopyr.

They have also used some Tier III herbicides – actinovate and fosphite – which we presume are a lot less toxic. (Edited to Add: They are not included in the graph above for that reason.)

Five Reasons it’s Okay to Love Oxalis – and Stop Poisoning It

The oxalis season is over, and the perky yellow flowers have vanished for another year. These Bermuda buttercups will be back next year to herald the spring, bringing joy to those who love them, irritation to those who hate them, and Tier I herbicides targeted at them in San Francisco’s so-called “Natural” Areas.

oxalis in glen canyon feb 2011

THOSE WHO HATE OXALIS AND WANT TO POISON IT  WITH GARLON

These flowers are so visible in spring that Bay Nature magazine did an article about them in March 2015: A Natural History of the Little Yellow Flower that’s Everywhere Right Now. It quoted Jake Sigg, the retired SF Recreation and Parks gardener who is considered the doyen of San Francisco’s native plant movement. He hates oxalis pes caprae, which he considers extremely invasive. The article quotes him as saying that, without intervention, “in X many years Twin Peaks would just be one solid mass of yellow, and there wouldn’t be any other plants there…” The article suggested that an oxalis-dominated landscape “drives away coyotes, hawks and owls that feed on grassland foragers, and the situation is especially dire for endangered Mission blue butterflies, which depend heavily on native wildflowers.” Most of those ‘facts’ about oxalis are mistaken as we’ll explain below.

Mr Sigg’s theories align with those of the Natural Areas Program (NAP) of the San Francisco Recreation and Parks Department (SFRPD), which uses the herbicide, Garlon (triclopyr) to battle oxalis  despite its dubious efficacy for the purpose.  San Francisco’s Department of the Environment San Francisco’s Department of the Environment classifies Garlon 4 Ultra as Tier I: Most Hazardous. It’s listed as HIGH PRIORITY TO FIND AN ALTERNATIVE (their caps). Since oxalis is the main reason NAP uses Garlon, the alternative we propose is – don’t use Garlon or anything else on oxalis.

An article on SaveSutro.com, based on a detailed study by the Marin Municipal Water Department, describes some of the issues with Garlon:

  • Garlon “causes severe birth defects in rats at relatively low levels of exposure.” Baby rats were born with brains outside their skulls, or no eyelids. Exposed adult females rats also had more failed pregnancies.
  •   Rat and dog studies showed damage to the kidneys, the liver, and the blood.
  •   About 1-2% of Garlon falling on human skin is absorbed within a day. For rodents, its absorbed twelve times as fast. It’s unclear what happens to predators such as hawks that eat the affected rodents.
  • Dogs  may be particularly vulnerable; their kidneys may not be able to handle Garlon as well as rats or humans.  Dow Chemical objected when the Environmental Protection agency noted decreased red-dye excretion as an adverse effect, so now it’s just listed as an “effect.”
  •  It very probably alters soil biology. “Garlon 4 can inhibit growth in the mycorrhizal fungi…” ( soil funguses that help plant nutrition.)
  •  It’s particularly dangerous to aquatic creatures: fish (particularly salmon); invertebrates; and aquatic plants.
  •  Garlon can persist in dead vegetation for up to two years.
twin peaks - jan 2015 - imazapyr and garlon for poison oak cotoneaster oxalis

Natural Areas Program uses Garlon on oxalis

First, a little about the actual natural history of oxalis. This plant doesn’t set seed in California, and spreads entirely by sending out roots and forming little bulbils (like tiny potatoes) underground. It’s usually found where the soil has been disturbed by activities such as road-building, gardening, or trail-building. In some cases, the disturbance come from landslides or something similar. It can’t stand frost. If we do nothing,  it would tend to die down rather than spreading uncontrollably.

In disturbed landscapes, it can spread fast. For this reason it can be a nuisance in gardens. People don’t want to leave their gardens alone for years to let nature take its course with the oxalis, and not every garden design includes brilliant yellow as the dominant color for a few weeks. The only way to eradicate it in the short term is to dig it out carefully every time you see it, and make sure you get most of the bulbils. Or use strong herbicides, which may not work.

In a natural landscape, though, it’s a different story and here’s why.

1) OXALIS IS GOOD FOR BEES AND BUTTERFLIES

Oxalis is actually an excellent plant for bees and butterflies.  When blooming, it provides “copious nectar.” In fact, it generously gives away its nectar. Since it doesn’t set seed, it doesn’t benefit from pollinators – but it’s a food source for honey bees, bumblebees and butterflies. (You can read a rather technical description of the plant HERE in a 2-page PDF note from UCLA’s Barry A. Prigge and Arthur C. Gibson.)

In fact, a recent 2014 study shows that plant communities with exotic plants had more plant species as well as more pollinators, that pollinators didn’t prefer native plants, and that even some specialist pollinators depended on introduced plant species.

It’s true the Mission Blue butterfly needs (native) lupine as its nursery plant. (It doesn’t depend on any other native wildflowers – only three varieties of lupine.  Incidentally, one of the key nectar sources for the Mission Blue butterfly is an invasive non-native Italian thistle: Carduus pycnocephalus).

Lupine has been planted on Twin Peaks as NAP attempts to reintroduce the Mission Blue butterfly there. But lupine is also a plant of disturbed areas, which means that NAP must maintain it or it will die out as the area stabilizes. They have to keep planting it, weeding, and trimming the grass around the lupine patches to make it attractive to the butterfly. An SFRPD report on the reintroduction project said “unmanaged habitat deteriorates quickly.” Presumably, they don’t use Garlon near the lupine patches, since it would likely kill that too. Despite what is implied in the Bay Nature article, it’s not oxalis that’s the issue. The real problem is another native plant, the coyote bush which takes over grasslands in a natural succession.

2) OXALIS IS GOOD FOR WILDLIFE

Oxalis bulbils are a food source for wildlife. Gophers and other rodents eat them. In fact, the Bay Nature article says, “Their spread is abetted by pocket gophers and scrub jays, which have been spotted carrying the bulbs and caching them in the ground—effectively planting them in new areas.”

Since gophers are a foundation species in the food web, being dinner for predators from hawks to coyotes to great blue herons, these plants actually provide habitat benefits whether or not they’re flowering, because the bulbils are there all year.

gopher-twin-peaksWhere there are gophers, the predators follow. Like the coyotes in these pictures, which clearly haven’t been driven away by a landscape dominated by oxalis.

coyote pouncing in oxalis field - copyright Janet Kessler

coyote pouncing in oxalis field – copyright Janet Kessler

coyote in oxalis field - copyright Janet Kessler

coyote in oxalis field – copyright Janet Kessler

3)  OXALIS DOESN’T LEAVE THE GROUND BARE

The article says that oxalis leaves “bare ground during the six months of the year oxalis doesn’t flower.” That’s not true either.

oxalis interspersed with grasses and other plants

oxalis in glen canyon feb 2011The spectacular yellow bloom of the oxalis – valuable because it the mass of color attracts honey bees and bumblebees – gives the impression that it’s the only plant there.  But though it visually takes over the landscape when it’s in bloom, it naturally grows interspersed with grasses and other plants. Like in the picture above.

In fact, oxalis tends to enrich the soil with phosphorus, which is good for grass.

So when it finishes blooming, as it has by now – you don’t get bare ground. The picture below shows the same area as the first picture in this article – but it’s after the oxalis bloom is over. It’s a grassland.

glen canyon after the oxalis season

4)  OXALIS HAS LITTLE IMPACT ON “NATIVE” PLANTS

One argument – related  to the ‘bare ground’ argument – is that oxalis takes over grasslands and destroys them, particularly the native grasses. However, grasslands in most of California including San Francisco are dominated non-native grasses. The change occurred over 100 years ago, when these grasses were planted for pasture. So the grassland that NAP is defending with herbicides are primarily non-native anyway.

oxalis and california poppies sm But anyway, what’s the evidence that oxalis is actually damaging native plants?

It’s true some European studies do suggest that an increase in oxalis is associated with a decrease in native plants diversity -though whether it’s a cause is unclear. It may just be benefiting from human activities that disrupt the landscape. Another study put oxalis head-to-head with a native annual grass, lolium rigidum. The native grass tended to dominate. Their conclusion: “Oxalis is a poor competitor. This is consistent with the preferential distribution of Oxalis in disturbed areas such as ruderal habitats, and might explain its low influence on the cover of native species in invaded sites.

The California Invasive Plant Council rates its invasiveness as “moderate,” considering it as somewhat invasive in sand dunes and less so in coastal bluff areas.

In San Francisco, every place where oxalis grows is already a disturbed environment, a mix of non-native grasses and plants with native plants (some of which have been artificially planted).  Here,  oxalis appears to grow happily with other plants – including, for instance, the native California poppy in the picture above.

5) KIDS LOVE IT AND IT’S EDIBLE

Children love oxalis, both for its pretty flower and for the sour taste of its edible stems.

Even small children love gathering posies of Bermuda buttercups (though picking flowers is technically prohibited in Natural Areas). The flowers are surprisingly hardy for wildflowers, and in a glass of water last quite well as cut-flowers.

The plant is edible, and its tart leaves make a nice addition to salad. People enjoy snacking on its sour stems. Besides Bermuda buttercup, it’s also called ‘sourgrass’ and ‘soursob.’ It does contain oxalic acid (as does spinach, for instance), and so you probably wouldn’t want to make a meal of it. Though in South Africa it’s made into soup.

Adding Garlon to it is probably a bad thing.

Photo credit: Badjonni (Creative Commons - Flickr)

Photo credit: Badjonni (Creative Commons – Flickr)

CONCLUSION

From our current evidence, there’s no sign that oxalis has a negative impact on wildlife, and plenty of evidence it’s already part of the ecological food web of our city.  The evidence also suggests it’s not having a negative effect on other plants in San Francisco either. Lots of people find this flower attractive; one writer described it as the city smiling with Bermuda buttercups.

In any case, even Doug Johnson of the California Invasive Plant Council doesn’t think it’s worth attacking at a landscape level: the payoff isn’t worth the expense. Removing it from the hundreds of acres in Natural Areas isn’t as simple as eradicating it from a small yard where it’s clashing with the garden design. It requires a lot of work, a lot of powerful herbicides, a multi-year effort – and for what?

The justification for using strong pesticides like Garlon to control it is weak. We call on NAP to stop using Tier I and Tier II herbicides altogether.