How far are scientists from being able to engineer dedicated weed killers . . . targeting a single species of plant, and leaving everything else alone? My yard is being taken over by morning glory vines, and I’d pay a small fortune for something that I can just spray everywhere.
Selective herbicides exist. There are some strong weed killers that can be sprayed over entire lawns without harm to the desirable grasses.
However…
Your vine needs to be pulled, and prior to its annual seedlings taking root, you need to put down a blocker in early spring or late winter that keeps all the seeds it drops from germinating.
Destroy the vine and roots as best you can, then treat with a pre-emergent that stops seeds from germinating (also the best way to control weeds and crab grass).
You need to attack the vine itself, but also address the hundreds/thousands of seedlings that will be back to haunt you.
Here are some sites with tips on controlling morning glory.
http://www.humeseeds.com/mgwb.htm
http://www.jlgardencenter.com/uploads/handouts/Morning%20Glory%20Control.pdf
Noote that they all call for persistence, and possibly even a multi-year attack.