Hemp Dogbane and Milkweed...herbicide?, mowing?

I am fighting a surge in both of these weeds in spots in my grass hay fields. It comes in strong after 1st cutting, and is taller than the grass, so I suppose i could weed wipe it. I can also top clip it to reduce seed formation. Or I could spray it and wait before second cutting of grass hay. Temperatures are near 90F so herbicides are less effective and volatile. 

 

I would like to hear your experiences.  timing? What herbicide? Does clipping help? Same herbicide for both weeds? Weed wiper experience good or bad? 

Thanks for your input.

Hemp Dogbane and Milkweed...herbicide?, mowing?