- Author: Jeannette E. Warnert
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.
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
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.