Using herbicide in a public park

What a quandary! Our first community association contest for an ugly area that needs beautification has just picked a winner! It's a lovely little 'pocket park' on a single lot donated to the city by the owner on his death (he had no family). The city maintains it, sort of, but it's overgrown by a rampant weed plant known as Japanese Knotweed (polygonum cuspidatum). I found it in PlantFiles and it's almost impossible to eradicate. 23 negatives! http://davesgarden.com/pf/go/32028/index.html

We (the Trees & Greenspace Committee of the community association) are now grappling with the larger public policy issue of using a herbicide in a park (albeit small). Do we go for the labour-intensive and not usually successful non-chemical solutions discussed in the PlantFiles postings, OR do we fence it off for a month, bring out the big guns (herbicide) and just get rid of it?

Or do we just give in to this bully and forget about trying to make this park a better place for its users?

If you could smother them effectively, why not pull what you can and smother the rest with a cover, like cardboard and mulch or similar for a month or so?

A month or so of smothering won't leave him with dead knotweed.

The neighbour to this park has laid down black tarps over his whole back yard for three years (going on four now). He still gets shoots. Smothering is a nice idea, but with this plant, it clearly doesn't work.

The committee is divided on using herbicide. I'm advising now that the park users all be informed about the weed and that they all (and their little kids) make a project of always pulling it out when they see it. At least this will stop photosynthesis and weaken the roots. We can deal with the herbicide issue over the long term, the 'combo' approach suggested by Equilibrium.

Really glad you're not going to give in to the bully. Good for you.

What about distilled white vinaegar as a more friendly herbicide?

We are still fighting field bindweed in our community garden, but it is far less vigourous than when we started. Keeping to pulled to weaken the root system has been a key with bind weed. Building the soil microbe community has helped tremendously with that as well. Most weeds need a simpler rhizosphere population then domestic plants and will dissappear as the beneficial mycorrhizae develop.

Vinegar and salt have both been suggested, and we will try those first. Stay tuned for results!

How are things going?? Any noticeable results yet???
Inanda

The park users have been pulling up the shoots as soon as they show... so it looks OK, but if they lose interest, I'm pretty sure it will grow back. We've also asked them to let the pulled shoots dry to paper in the hot sun before discarding, or to put them in a black plastic garbage bag to let them cook. We don't want this to go to the landfill!

Good oh. I'll keep an eye on this thread.
inanda

Good going andycdn! Looks as if you're on your way to being rid of that plant.