Unwelcome weed 'stinkwort' spreading quickly in California

UC Weed Science

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Weed control, management, ecology, and minutia

Author: Jeannette E. Warnert

Published on: August 14, 2013

Invasive weed stinkwort, Dittrichia graveolen, can spread rapidly on overgrazed land, river and stream banks and roadsides.

UC Cooperative Extension experts are advocating for aggressive control of invasive stinkwort to prevent it from becoming an established California weed, reported the Sacramento Bee. Joe DiTomaso, UCCE specialist in the Department of Plant Sciences at UC Davis, said he believes CalTrans will have to treat stinkwort as an invasive of high and unique concern if it has any hope of controlling its spread.

Stinkwort made its first California appearance in 1994, but remained quite rare until the mid-2000s, when it began spreading rapidly. Stinkwort is now found in 36 of the state's 58 counties, particularly along roadsides.

"If it gets a major foothold and produces millions and millions of seeds, then the seedlings will grow and they can form a carpet," DiTomaso said. "Then it would block light and prevent the growth of more desirable species – like native plants. It will out-compete them, and that is a concern."

Another troubling aspect is that the weed has been seen in vineyards, said John Roncoroni, UCCE advisor in Napa County, a weed science expert.

"I've seen it on the roadsides in Napa, and it's just encroaching into the vineyards at Napa Valley College," he said.

Tags: grapes (3), invasive weeds (90), roadsides (10), stinkwort (1), vineyards (6)

Comments: 5

Comments:

by Steve Kelem

on September 14, 2015 at 3:45 PM

Thanks for the heads up. Can you post a better picture (or more pictures) and more info on how to identify stinkwort?

Reply by Brad Hanson

on September 15, 2015 at 8:01 AM

Steve,
There's a good weed ID tool at the Weed Research and Information Center that can help ID this and other weeds. Here's a URL.
http://weedid.wisc.edu/ca/

Also, there was a good article on this particular weed in CA in the journal "California Agriculture" in June 2013 by Brownsey, Kyser, and DiTomaso (Cal Ag volume 67, pages 110-115). Here's a link for that: http://californiaagriculture.ucanr.org/landingpage.cfm?article=ca.v067n02p110&fulltext=yes

by carol

on December 28, 2015 at 7:43 AM

i believe that i may have stinkwort; it has an irregular or lacey shaped leaf; becomes established in late summer; has thousands of cream or gold colored seeds and then stickery growths that turn purple or dark burgundy; large thick roots that extend horizontally in mature plants. I have sprayed twice during the late summer with round-up and weed begone combined with amonia and soap; but they return again. They have a strong chemical smell when disturbed.

by Frank Kirkpatrick

on October 7, 2022 at 10:14 AM

Interested in its origin, I assume it’s not Native to California

Reply by Gale Perez

on October 7, 2022 at 10:57 AM

Hi Frank,
The article (by Brownsey, Kyser, and DiTomaso) that Brad Hanson mentioned in his response has some good information. Here is the pdf: https://calag.ucanr.edu/archive/?type=pdf&article=ca.v067n02p110.