George,

Here is the link I provided earlier.

http://www.flameengineering.com/Flame_Weeding.html

http://www.agronomy.ucdavis.edu/LTRAS/itech/flame.html

Here's another

http://www.tejassmokers.com/newproducts_page7.htm

I plan to use a burner here but haven't tried it yet. You don't actually "burn" the weeds, they are more "Scorched" which stops photosynthesis.

Chip