Containing Aspen Sprouts and Weeds

My neighbor has planted 6 aspens two feet apart one foot from my fence. How can I prevent the roots and sprouts from invading my yard.

I was thinking of renting a trench digger and digging a two foot trench on the margin of my property, filling it with rock salt, and lining it with heavy plastic on my side to prevent leaching to my own garden.

Will this take care of these trees that were so blatently planted to guarantee my neighbor's privacy.

You might try some sort of root barrier like you would buy to contain running bamboo. I'm not sure if it would work on trees though since their roots go deeper down than bamboo does. Same thing with your trench, the roots might still be able to go underneath a 2 foot trench. I think they could punch through black plastic too, so I'd get something sturdier. And the rock salt has the potential to be able to kill off the trees on your neighbor's side too and that could get you in trouble. I don't know how the laws work in Canada, but in most places here in the US you're allowed to cut back branches and things like that if they're hanging onto your property, but only if what you do doesn't kill the tree. If you kill the tree, then your neighbors can hold you responsible.