Toad in the Hole

June 08, 2006

Red Alert

Here's yet another new invasive nasty in the San Francisco Bay Area.


From Susan Schwartz of Friends of Five Creeks, a restoration group.

I'm hoping you will help look for the bright-yellow, leafless, parasitic vine shown in the attached photo. If you find it, please inform Vince Guise of the Alameda/Contra Costa Weed Management Area andme. California has many dodders, but no other forms these bright yellow tangles in broad-leaved trees.

This plant is Japanese dodder,
Cuscuta japonica. It is a new invader in California -- our restoration site at Adams Street on Cerrito Creek is apparently only the third reported instance. But the second was at an apartment building in San Pablo, so there may well be others. That is why I'm asking your help.

This parasite can infest a wide variety of trees. At Cerrito Creek, it's on willow, plum, and elderberry; at San Pablo it infested pittosporum. It spreads by seed and vegetatively, by bits and pieces -- the long, succulent tendrils break off easily. Once it finds a host, it sends root-like structures called hausatoria into limbs, sucking the host plant's water and nutrients. It forms dense tangles and weakens or eventually kills the tree or bush.

The plant has herbal uses in Asia and may be being brought in for that reason. There is a Department of Agriculture quarantine, but those are often ineffectual. Like many invasives, it has the potential to spread rapidly and widely in wild lands, gardens, and orchards.

Department of Agriculture advice is to inform them rather than try to eradicate it yourself. If you do try, their advice is to remove the entire tree or bush down to the ground, double-bag everything down to small fragments, and make sure the bags are deeply buried in landfill (that is, do not compost).

She added in a second note: "As with many invasives, you can find websites about the threat, and also web sites about how wonderful it is as medicine and food. Seed brought in as medicine is supposed to be sterile, but a recent shipment was tested and all was viable."

I hate situations like this, where one has to destroy a formerly healthy and handsome tree or plant to prevent the deaths of more plants -- though it's, I don't know, not quite a consolation to know that the infested trees are pretty much doomed anyway. This is apparently much nastier than the familiar orange dodder -- itself an agricultural pest -- that we see every year in the pickleweed marshes around the Bay.

Photo not copyrighted, credit: Friends of Five Creeks. Spread the word. Just don't spread the weed.

Posted at June 8, 2006 07:22 PM


Aiyiiiii!!! The evil and dreaded Dodder! I have recurring nightmares about that stuff (it once took over the entire ground cover section at a nursery where I worked and over a hundered flats had to be destroyed). My theory is it comes from another planet.

Posted by: Vibrating Liz at June 9, 2006 01:45 AM

Oh yeah, and this looks worse than the usual. Have you ever touched the stuff? Cool, slightly dampish, non-plantlike... weird.

Posted by: Ron at June 9, 2006 06:01 AM

Damn, I think I saw some of this on diablo last week. I'm going back tomorrow: I'll have to take the GPS and get coordinates if it's the same stuff.

Posted by: Chris Clarke at June 9, 2006 08:54 PM

That's awful! It makes my town's latest problems with leafy spurge ( absolutely trivial by comparison.

Nasty, nasty stuff, dodder.

Posted by: Sara at June 12, 2006 03:39 PM