Emergency Stinkwort Bashing

Huge patches of Ditttrichia graveolens, stinkwort, in Scotts Valley
Saturday morning, I was going to work on my north garden stone steps (seven done, five to go), but an appeal from weed warrior Ken Moore got me out in the field instead.

Ken Moore attacking a large stand of Dittrichia graveolens - stinkwort. At this point in the year, cutting it off at the base should stop the plant growing. It's an annual.

On an earlier trip, I found two huge patches of Dittrichia graveolens - stinkwort in the Glenwood area of Scotts Valley (thanks to a tip by a resident there via social media). They were going to seed and we had to do something about it.

Dittrichia has small yellow flowers and Small seeds with pappi (hairs)
Do you live in California and are unaware of the dangers of stinkwort? Please see this earlier post to learn how quickly it has spread in our state, and how to control the spread. Invasive weed experts agree this is the fastest moving invasive weed they have ever seen.

On the exploratory trip, we found stinkwort along Glenwood Drive itself,

Stinkwort flowering opposite Scotts Valley High School on Glenwood Drive
And in an open space preserve near the road, an undeveloped space between Glenwood Drive, and a large park containing baseball diamonds.

Stinkwort in Siltanen Park in Scotts Valley
It has clearly been here for two or three years, unidentified.

Once it flowers stinkwort will go to seed very quickly, even quicker after it's pulled and left lying on the ground.

But it only germinates in open sunny places, and Ken found a shady area where we could pile up the pulled plants. The seeds live for three years or so, maybe less. So - this is just the best we could do.

Another volunteer, Chuck, piling plants in a shady area nearby.
At this point all we could hope for was to reduce the spread. Next year we'll be back around June and early July, to pull before the flower buds start forming.

Chuck worked with a hand tool, and mostly so did Ken. The brush cutter overheated after just a few minutes.

Chuck whacking with a sharp hand tool

I and another volunteer, Jill, mostly pulled the cut weeds onto tarps and dragged them to the growing pile. It was hard work in very hot weather - it's been hot and dry all month.

But we prevailed!





It took four hours for four people to clear that one patch, and Ken, Chuck, and Jill returned today - I had propagation group to attend - and they finished off the rest.

But I did feel sorry for the tiny little field mice who were living in the stinkwort. As we felled the last plants, they scurried out looking for shelter.

Wee sleekit cow'ring timorous beastie!
If you see stinkwort in your locale, please do your best to tackle it, even now. For smaller infestations, securely bag and seal it, with a little water so it will rot. Leave it in a safe place for as long as possible. I'm not sure how long it takes - maybe a year. And next year, pull early and pull often, and you'll get rid of it pretty quickly. If you pull it before flowers start to form, you can just leave it lying.

It's worth the effort - or should I say, you'll really regret it if you don't make the effort - when you see the consequences of ignoring this blight. We may not be able to keep it off the freeway medians, but we can keep stinkwort out of our gardens and parks and wild areas.


ryan said…
Good work. Freshly cleared ground is really satisfying. I've seen this one along the freeway, but I didn't know what it was called.
Country Mouse said…
Yes, we were pleased indeed to see it gone, Ryan - though we'd have been more pleased to do it in June/July before flowers formed. Now you've seen it you'll be able to recognize and pull it too!
Janet Barton said…
Hi, How did the experiment of piling the Dittrichia in the tarp in the shade work out?
We are dealing with a large infestation and bagging, but it would be good to know if tarping it in place might be a good option.
Country Mouse said…
Hi Janet - I have to apologize. I just now was looking at some administrative settings on my blog and saw that your comment was somehow pending and awaiting "moderation." I'm mystified - I've been dealing with other comments in moderation since yours was submitted and didn't see yours. Anyway...

There was no follow up as far as I can tell at this site. I do not have bandwidth myself - I'm working solo on three meadows very close to where I live, and I'll be posting about Year Three of that effort when stinkwort starts emerging in June.

This whole area of Scotts Valley, the area I wrote about in this post, is sort of out of control I think - and efforts are focusing on an important grasslands preserve located near this bad outbreak.

I revisited the site a year ago or so and there was less stinkwort but still quite a lot. I didn't see any stinkwort growing from the big piles we left under the trees.

We did not put tarp over them - you picked me up wrong there - we just slid the piles to the deep shade on a tarp.

I will go again this year to check it out write about it when I do a related post.

The latest advice I've received is to bag in clear plastic and add water and leave in the sun to cook! I may try that this year, if I have need. Is it possible that tarping could have a similar effect? I'm not sure - can't advise about that.

Last year (2015) my local infestation was smaller and I got to it mostly before buds formed. I squished the heck out of the few plants I picked that had buds - turned them to slime basically! That is not a solution that scales up!

This year I fear every Dittrichia seed that could possibly germinate will, given how everything else is flourishing with the rain we've had. It'll be interesting. I hope your efforts went well and you are getting on top of it.