Fence line brush control

For years, I have been spraying my fence lines with brush killer to keep the brush from growing up through the fence.  I get a lot of brush hereabouts--much of my pastures are bounded by woods.

 

Two years ago, my neighbor planted peach trees on their land right next to one of my more difficult pastures to control brush growth.  Peach trees are planted about 25' from the fence line.  Now, I know peach trees are tremendously susceptible to 2,4D and the likes.   (BTW, the recommended set back for planting peach trees is 60'.)

 

I need to control the brush growth in this pasture but am very worried about damaging their trees.  

 

Have any of you used Spike 20 or something similar?

 

Any suggestions?

 

Thanks

 

Ralph

Fence line brush control