Stinkwort could be our teacher of grassland ecology or the worst weed ever

Stinkwort along I-280 at the Page Mill Road exit in Palo Alto.

Stinkwort along Hwy 92 in San Mateo, growing in concrete expansion joint in median.


Stinkwort plant making seeds in a field along Los Trancos Road in Portola Valley


The STINKWORT (Dittrichia graveolens) can be a teacher of grassland ecology or the worst weed ever, depending on what side of the California grassland fence you are on. --Are you maintaining exotic grasses for hay and grazing or are you restoring the California native bunchgrasses and wildflower meadows?

Copyright © 2013, 2017 by Craig Dremann, The Reveg Edge, Box 361, Redwood City, CA 94064 (650) 325-7333

The Stinkwort was first noticed in California in Santa Clara County less than 30 years ago. The infestations on the San Francisco peninsula are mainly spreading along the roadsides, and in 2017, this new weed is not being regularly eradicated each summer and autumn by any road management agencies, like those of Towns, Cities, County road crews or Caltrans.

Now that this new weed has spread to infest more than half of California's counties, government agencies are starting to pay attention, especially since this noxious weed is showing up in the Napa County vineyards and there are concerns that the plant might give an off-flavor to the wines.

Also there are concerns about the plant going into the rangelands of the State, and injuring stock.

BLM on their web site has issued the following notice:

Warning! Touching stinkwort can cause dermatitis, itchy skin, or blistering. Grazers that eat this plant can produce tainted milk or meat. When the seeds are ingested by grazing animals they can cause inflammation of the small intestine, and can lead to pulpy kidney disease or sudden death.

Stinkwort is a California native tarweed-mimic, in that it has sticky stems and leaves and grows and flowers in the summer, after the annual weed grasses have died for the year. The original tarweeds could be called "exotic grazing-animal antibodies" in that they interfere with exotic animal grazing in California, and did not allow the animals to graze the land to barren dust and desert.

After 1865, when the perennial native grasslands were largely grazed to dust during the two year drought (William H. Brewer's accounts), then the non-palatable native plants like the tarweeds flourished in California between the 1870s to the 1920s.

The density of the tarweed in the 1920s in California grasslands can be seen in photos taken by Frederick Clements when he worked at Stanford at the Carnegie Institution. Since that time, ranchers have worked diligently to exterminate the native tarweeds and the other summer-blooming native wildflowers from rangelands. Tarweeds were probably largely wiped out after the invention of herbicides in the 1950s, so by the 1970s were absent in 99% of California grasslands.

Now, this exotic tarweed-mimic arrived, spreading quickly to fill the empty ecological niche left by the essentially extinct native tarweeds and other summer-blooming native plants. Stinkwort has now put a spotlight on the last 200 years of grassland mis-management in California.

When the original California native grassland was exterminated, it included many tarweed species and other summer-blooming members of the sunflower family like the Golden Aster, the Gumplants, the beautiful Lessengia and many others. Also other summer-blooming native plants like the Buckwheats, Wild Licorice, Spanish Clover, and the Milkweed plants that are needed by the Monarch butterflies to survive.

The Europeans and Americans were hoping that the palatable exotic grasses that were useful for grazing, plus the exotic filaree and exotic clovers and vetch species, would be the only plants to replace the now spatially-extinct native bunchgrasses and wildflowers.

However, an ecological rule is--When you exterminate an entire native grassland ecosystem and converting it to an exotic-plant biome, it is impossible to have fields of only the desirable wild oats and not expect the weedy exotics like Medusa head grass, Stinkwort and Yellow star thistle to follow. You cannot have the desirable filaree without the potential of having Stinkwort, Cheatgrass, or Italian thistles for example.

So, the battle begins for the empty tarweed ecological niche in California. If you are growing grapes for wineries, or grazing lands now covered with exotic grasses, or trying to maintain weed-free roadsides, expect to budget tens to hundreds of millions of dollars to keep Stinkwort from filling in that now-empty tarweed ecological niche.

Stinkwort's almost magnetic attraction to the open tarweed niche, plus the seed pappus allowing it to blow in the wind, will help this plant to eventually become perhaps one of the most hated weeds in California or maybe the worst weed in the Western United States.

However, if you are doing Ecological Restoration of the native bunchgrasses and wildflower fields, then this new weed can become your teacher, to grade your projects. Stinkwort can be used to indicate, wherever it grows, that you still have some more work to do on that spot of land, to fill in all of the proper native grassland ecological niches and puzzle pieces.

Who is financially responsible to pay for the eradications--SF Peninsula example.

The Stinkwort was put on the State Noxious weed list, which means that it was automatically declared under law, to be a "public nuisance". So then, the Food and Agriculture codes giving the County Agriculture Commissioners the power to issue abatement orders, should have followed immediately thereafter, in order to stop the infestations of this new weed from spread from property to property.

The Stinkworts have been making their way up the San Francisco peninsula, following Caltrans roadside up US 101 and I-280, then started moving across the Peninsula along East-West highways like 92 from US 101 to the Coast Highway One. Then, these roadside infestations of scattered plants along the freeways, start spreading downwind in a cone-shaped pattern to start large infestations. It looks like small fires getting started, and then in turn, throwing embers downwind, to start larger fires.

The Town of Los Altos Hills and Stanford have the largest infestations so far. The Stinkworts growing along nearly every roadside in the Town of Los Altos Hills, and several multi-acre infestations on the Stanford Hills between I-280 and the Dish, thick along the trails off Foothills Expressway and also on either side of the SLAC building, getting into the Jasper Ridge preserve, and also getting started in the middle of the 100+ acre Woodside Horse Park along Sand Hill Road.

On the SF Peninsula, all of the remaining native grasslands are threatened, especially the serpentine grasslands with many rare and Listed Endangered plants and insects that live between Palo Alto and the Crystal Springs reservoirs, plus the grassland habitat with their Endangered species on San Bruno Mountain.

In the Stinkwort's cross-hairs are Jasper Ridge at Stanford, Edgewood Preserve, SFPUC serpentine grasslands along the Crystal Springs lakes, and the grasslands of San Bruno Mountain. It has already been seen in three of the Mid-Pen. Open Space preserves, Monte Bello, Rancho San Antonio, and Fremont Older. A photo of Stinkwort plants getting established along the coast at Pilar Point was taken on October 31, 2017, so that means all of the grassland habitats along the Highway One are also at risk.

So who should pay for all of these infestations on the SF Peninsula? There are at least six agencies at fault for not abating a public nuisance, and have cause damages that will cost millions of dollar per year to eradicate that nuisance that has spread to neighbor's properties.

County Agriculture Commissioners so far, has not issued any abatement orders. The two County governments, Santa Clara and San Mateo are the agencies that are legally responsible for sending out the abatement notices to start the Stinkwort cleanup. And because their Agriculture Commissioners has not yet issused abatement orders to stop the Stinkwort from spreading each year, now they could be financially responsible for for the costs of all of the eradication on both public and private properties?

Negligent Roadside Maintenance managers and Negligent Land managers pay their share of the Stinkwort eradication and native plant restoration costs? Then, a list of land managers could be made from the SF Peninsula who have not adequately abated this new public nuisance on their lands, and allowing the Stinkwort to spread and infest their neighbors. For example, Caltrans, County Road maintenance departments, City of Los Altos Hills road maintenace, Palo Alto's closed baylands infested dumpsite and Mid-Pen. Open Space Trust infested preserves could be on that list?

ESTIMATED ANNUAL COSTS on the SF Peninsula. Estimated that to eradicate the existing Stinkwort, if the work started in 2017, a reasonable annual budget of $2.7 million would be needed to eradicate the Stinkwort on the Peninsula north of Cupertino.

Perhaps best to pool that money together and use half of those funds to hire professionals like to eradicate the plants on the roadsides, on the public lands and eradicate the plants on the private lands. And use the other half to grow out the necessary bulk local native seeds, and sow those native seeds to take the place of the Stinkwort to keep that weed out permanently.

The agencies who should be responsible for the Stinkwort costs, total $2.8 million--

Caltrans - $500K
Santa Clara County - $500K
San Mateo County - $500K
Los Altos Hills - $300K
Stanford - $200 K
Mid-Peninsula Open Sapce - $200K
National Parks Service - $100K
Palo Alto - $100K
Portola Valley - $100K
POST - $100K
SFPUC Crystal Springs - $100K
State Parks - $100K

Recent Santa Clara County Court case about Public Nuisances. People v. Atlantic Richfield Co., Santa Clara Superior Court Case No. 1-00-CV-788657, the court ordered three of the paint companies to pay $1.15 billion into a fund dedicated to abatement of lead paint in pre-1978 home.The judge found that a plaintiff need not show that a defendant is the sole cause of the injury, but rather that its conduct played more than an infinitesimal or theoretical part in bringing about the injury, damage or loss. This court case greatly expanded who is legally liability to pay for abatement of a public nuisance, and for paying damages.

FINAL Stinkwort FIX. By commercially reproducing the bulk seeds of those local grassland native seed, they could be sown to fill in the empty ecological niche, and keep out the Stinkwort, the Yellow star thistle and any other weeds that are currently taking advantage of that empty niche.

This bulk native seed sowing needs to be done in November and December, after the weeds are sprayed in August to October, so the native seedlings can suppress the stinkwort seedlings the next summer.

Invent the best native sowing methods? A significant portion of the native seeding budget needs to be set aside, in order to hire professionals in Ecological Restoration to invent the best sowing methods for each native seed species, especially to produce successful planting along Caltrans roadsides, and within the public grassland preserves like Mid-Pen's lands, because neither agency has been successful so far in restoring native grasslands on a large scale in California yet.

by Craig Dremann.
Overview of survey area, above.

SURVEY Hwy One - South of Princeton - HERE

SURVEY Hwy 9 - From Highway 35 to Saratoga - HERE

SURVEY Hwy 35 - South of Hwy 84 - HERE

SURVEY Hwy 85 - From Saratoga Av. north to US 101 - HERE

SURVEY Hwy 85 - Saratoga Av. southward - HERE

SURVEY Hwy 92 - Hwy 101 to I-280 - HERE

SURVEY Hwy 92 - I-280 to Hwy One - HERE

SURVEY US 101 - San Bruno to Hwy 92 - HERE

SURVEY US 101 - Hwy 92 to Woodside Road - HERE

SURVEY US 101 - Woodside Road to Lawrence Expressway - HERE

SURVEY I-280 - Hwy 92 to Sneath - HERE

SURVEY I-280 - Hwy 92 to Edgewood exit - HERE

SURVEY I-280 - Edgewood exit to Page Mill Road - HERE

SURVEY I-280 - Page Mill Road to Foothill Expressway exit - HERE

SURVEY I-280 - Foothill Expressway to WInchester Blvd. - HERE







SURVEY SAN BRUNO MTN.-Guadalupe Parkway - HERE




Updated November 19, 2017. Back to Craig Dremann's main Contents page.