While exhibiting at the Virginia Biological Farming Conference in Richmond this past February, I met someone from our area that grows organic hops for some of the finer micro-breweries in Nelson County, Virginia.
The question of flame weeding naturally came up in the conversation and while I didn't know any growers who flamed their hops, I was determined to find out. Here is a video that I feel demonstrates the safety and effectiveness of flame weeding on one of our nations oldest and favored crops. Note the fact that the burning plant reside has a limited burn life - It will use its own fuel and then, (as the author of the video states in his comments on the YouTube post) "Added benefit: combustion of weed material provides an immediate source of potassium to the hop crown area!" Also note the safe practice they have implemented where they have tilled the soil between rows to keep the flames from spreading.
The flame weeding torch you see being used in this video is available at www.WayCoolTools.com