I've burned them before. It's pretty effective if you understand the true goal. Despite the name you do *not* want to actually burn the weed! Burning the weed is no better than cutting off the part you burned--which obviously doesn't work very well. The objective is to give as much as possible of the weed a light singe--it takes a bit of experience to even see anything. The weed spends all it's energy healing the damage and dies.