Stopping the stink: Los Altos Hills launches annual assault on stinkwort weed

Megan V. Winslow/Town Crier
A cyclist pedals past stinkwort growing along Natoma Road in Los Altos Hills last week. The town has hired a pest control company to spray the invasive weed with an herbicide. The application is scheduled to start Monday and last for a few days.

Kit Gordon wrapped plastic around her prop at last month’s Los Altos Hills City Council meeting.

“If anyone wants to have a closer look – anyone in the audience – of what stinkwort is,” said Gordon, raising the bundle of spindly green vegetation Aug. 16. “I don’t know if you want to pass it around.”

With mock gravity, Councilman Gary Waldeck responded, “It would be wise not to.”

It’s stinkwort season again, and the sticky, rash-inducing weed has returned to stand sentry along Los Altos Hills roads. As Gordon described in the Open Space Committee’s annual report to the council, management of the invasive Dittrichia graveolens species is a “rising concern.”

On Monday, a pest control company will commence spot spraying of an herbicide along roadways and pathways designated as stinkwort hot spots by members of the Open Space Committee. Application is expected to take three to four days. Garlon 3A, the chemical used, and Blazon, the accompanying blue colorant that marks spray sites, is Environmental Protection Agency-approved and considered safe for aquatic life, but residents who don’t want their road frontage sprayed may erect “Do Not Spray” signs.

“The Town recognizes possible concerns about use of herbicides and is committed to using them only in limited circumstances under strictly controlled conditions,” Public Works Director Nichol Bowersox wrote in an Aug. 30 letter mailed to residents.

Ongoing battle

This is the second consecutive year town officials have opted to spray for stinkwort, and Bowersox said the success of last year’s application combined with proactive mowing by town staff is evident by comparing the required coverage across years; in 2017, Pestmaster Services sprayed Garlon 3A on approximately 15 miles of roads and paths at a cost of $14,750. This year, the Reno-based company will spray approximately 7.2 miles at a cost of $7,895.

“We’re spraying half as much as last year, so we definitely did a great job last year of knocking it down,” Gordon agreed.

Spreading awareness has also helped, she said. With assistance from the Open Space Committee, the town has notified residents about stinkwort’s noxious qualities (in addition to causing rashes and headaches, the plant is flammable) through letters and fliers. Because stinkwort thrives in disturbed soil, construction sites are common areas for infestations, and committee members worked with Planning Director Suzanne Avila and her department to make its removal a condition of approval for projects in town. Now builders must clear the plant from their sites and the adjacent right-of-ways by Oct. 1 each year.

Los Altos Hills residents are not required to remove stinkwort from private property, but they are strongly encouraged to do so before it blossoms and goes to seed each year, typically around August or September. Each plant is capable of producing 30,000 seeds, which are easily dispersed via wind, water or human activity.

Wear gloves, long pants and long sleeves when pulling stinkwort to avoid exposure to its sticky resins, the Open Space Committee warns. Plants that have not flowered can be composted, but those that have should be bagged for disposal or taken to Foothill College the third Saturday of each month for the free GreenWaste Recovery yard collection service.

To view a map of designated spray sites and for more information on the town’s fight against stinkwort, visit

Schools »

Read More

Sports »

Read More

People »

Read More

Special Sections »

Special Sections
Read More

Photos of Los Altos

Browse and buy photos