That's pretty mean, but won't work since it doesn't affect humans uniformly. If the wind changes, the applicators would have it applied to them. And if it turned out to have some wonderful medical application Bayer wouldn't go to the trouble of picking it out of the woods and hedges, they'd farm it and there would be more of it than ever. What I'd like is some sort of Pocket Shot (tm) sprayer that I could carry with me on my walks so that whenever I saw PI -- and it's EVERYWHERE -- I could KILL it. The Pocket Shot would be leakproof and dripless and have 15 or 20 doses of something that would kill the whole plant even if applied only to one leaf.
The problem -- for me, anyway -- is that not everybody is allergic, or as allergic as I am. If everybody reacted like I did there would be a bounty on it. Sorry, birds.
Jack