Invasive humans (and their flora)

At a party in the San Lorenzo Valley town of Felton last night, I found myself chatting in a pleasant and typically Californian group of three - a Scot, a German, and a Frenchwoman.

We non-native Californians are all over the place. Unfortunately so are the plants we have introduced. My main battle at the moment is against the omnipresent South African import, Oxalis pes-caprae. (Pes caprae means goat's foot in Latin, I think.) It's not in flower right now so I grabbed a picture from the internet.
(Photo by Jonathan Alcorn, accessed 12/22/08 here: http://latimesblogs.latimes.com/lanow/photo/).

You'll recognize it I know, by its pretty yellow flower and clover-like leaves, though you may be more familiar with it as "sour grass" if you have children who like to suck on the flower stems. (Oxalis is poisonous but not in such small doses.)

I have been slacking off lately and the pes-caprae troops have received massive reinforcements. I want to root them out before they stock up on cannon balls -- I mean the little root nodules that remain in the ground when you pull them, making this Oxalis so hard to get rid of. My friend, the naturalist Jeffrey Caldwell, told me that gophers gather the nodules and store them for eating, which helps the weed to spread. I also believe they reseed freely. I've tried Roundup I confess in hard-to-treat areas and it is successful but only if you keep on squirting. I feel guilty every time I spray. Hand pulling is more effective, but again, only if you repeat repeat repeat. I'm seeing headway in the areas where I have been most diligent. But not victory. It's time for a Churchillian speech to keep up the spirits.

Or a new secret weapon.

I was cheered in this regard when I met Cameron Colson recently, an energetic young businessperson with a new application for power washing technology: invasive weed control.

We happen to have a power washer, and I'm going to give it a go on my own. Cameron has industrial strength machinery but the only specialized part is a special nozzle. He can take down trees! But I just want to see what it does to the Oxalis pes-caprae. The technique promises to turn all surface vegetation into a nice mulch, and, with three applications to blast away the regrowth, to significantly reduce the weeds. It's not only chemical free, but improves the health of the soil.

I'll write about my experience, and about Cameron's ideas and fledgling business, in another post.