Cant' hold out any longer... need to start spraying for weeds.

So I've held out as long as I can, but I admit it's time to start spraying for weeds in my hay.  There are two main problem weeds that I am dealing with, horse nettle and knapweed.  I know my neighbors field is where the knapweed is coming from, but I'm not sure where the horse nettle came from.  I don't want to just refit/reseed the fields as I'm sure that won't help too much.. just prolong the problem.

 

I do have a 3pt hitch sprayer, but I do not have a pesticide license.  Whatever I use also has to be OK to use on grass/timothy hay fields.  I know I'll probably kill all the broad leaf plants that I don't mind (like birdsfoot), but I'm OK with that if it means I get rid of the bad stuff.  What sprays would work in my situation?  When would be the best time to apply them?

 

Thanks in advance for all your help!

Cant' hold out any longer... need to start spraying for weeds.