Sunday, May 06, 2007

War of attrition

Over the past three weeks, I have devoted hours to uprooting this villain.

Name: Japanese knotweed a/k/a elephant ear bamboo a/k/a Mexican bamboo a/k/a fleeceflower a/k/a Polygonum cuspidatum
Identifying marks: bamboo-like hollow stems, reddish new growth, succulant white rhizomes with orange exterior
MO: spreads by underground roots . . . and spreads . . . and spreads

This invasive grows so quickly that it suppresses native species. Its science-fiction monster roots can run 12 feet deep and 20 feet distant from the stalks. Just a half-inch length of rhizome can sprout.

According to this very helpful publication by UC-Davis, control requires constant vigilance. The best eradication results from a combination of digging out the plant roots and applying herbicides. I'm committed to the first option and will be waging a war of attrition--apparently for the next several years.

A close-up of the battlefield: the muddy patch next to the neighbors' new fence. It's on its way to becoming part of a raingarden.

I have grubbed out roots, moved building rubble, added 7.2 cubic feet of peat moss, dug in several buckets of compost, and planted this lonely little forsythia Lynwood Gold. It will be joined in a few weeks by a plethora of clethra.

And, on an all together happier subject, the sunny beds along the back of the house are tearing along. The peonies have buds . . . and the buds have ants. Yay!


Peter said...

Good luck with the knotweed. In the UK (http:\\ it is such a problem that anyone found propagating it or otherwise causing it to spread can be heavily fined. It can be so rapant that it has been known to destroy building foundations when they have been built on top of old patches of this stuff. I have been constantly amazed at how much of it is growing in the area (Woburn MA).

In the past I have had similar fights with horsetail (Equisitum) and couch grass(Elymus repens). So you have my sympathy

Doctor Mom said...

Boy, is this stuff bad! Thanks for the link--and condolences!

Xris said...

I had to battle knotweed in Garden #3. The main source was the backyard of the adjacent abandoned property. It completely covered an area of about 20x20 feet and grew to 9 feet in height.

I did some guerrilla herbicide to try to control and contain it, with mixed results.

My technique used a) pruning shears, b) concentrated Round-Up, and c) a basting needle. I cut each stalk as close to the ground as possible, just above the lowest node, exposing an inch or two of the hollow tube of the stem. I took the basting needle, loaded it up with the Round-Up, stuck the needle through the stem joint, and injected the Round-Up into the stem.

This knocked it back, but still did not kill it. It came back weakened and stunted. If I had been able to do another application, I might have been able to kill it completely. However, bees and yellow-jackets took up residence in the abandoned porch, which had been my access into that yard, before I had a chance to renew my assault.

Under no circumstances let it go to seed, which happens almost as soon as it flowers.

Doctor Mom said...

Spent time this evening pulling up knotweed stalks that had crept into the lawn. Your surgical procedure is more appealling all the time, Xris. Thanks for sharing your wisdom!

carletongardener said...

I see that weed all over the place and am glad to know the name of it. Sounds like bad news.