I personally like the smoke method. I used to work maintenance at a summer camp and had to deal with wasps alot in the cabins. I would take a stick or broom handle and make a giant q-tip with a paper bag and light it. You can stick it as close to the nest as you want. For me, it seemed to stun and irritate them. If you make sure there aren't any still in the nest, you can knock it out on the ground and then light it with the burning paper, no nest no wasps (for a while anyway).