Salt will spread in the soil, and is just bad all around, as it will percolate down. I understand the temptation, just looking at that mess. Will the town be any help? Some towns will do rudimentary maintenance on vacant lots.

There is always Round-Up, although spraying that mess would be a real job. Some of those plants look like overgrown vegetables -was that somebody's garden once?

I can't see many species which spread by airborne seeds in your pictures. I can see especially dock, burdock and cleavers. So just spraying a strip along the fence should stop those weeds crossing into your plot.

If, as you say, the yard has been mowed in the past, is it possible to contact the owner and ask them to mow more often or if you can go in and mow?

Unless you own, or have the permission of the property owner, what ever you do to control those plants may lead you to court for trespass. Applying any type of poison to someone else's property may lead to even worse legal action.

Tread on this with due care.

A strip along the OP's side of the fence, obviously.