"Alan Grossberg" wrote:

It's not an attractive option -- especially for a 500 sq. ft. area -- but
you could probably kill it or put a good dent in it with a cover of black
plastic mulch for 3-6 months.

Actually what also works is glass and sun light. If you ever left storm
windows lying flat on your lawn for a few hours, you may have come back
to a big brown spot. Some salvage yards or building material surplus
outlets sell storm windows for very little. You need to smash the plant
material down so that there is very little space under the glass and it
can build up enough heat to cook everything.

The other option is a propane weed burner. It will burn the plants and
weed seeds all at once.