"now i got the bill, and they sprayed headline on all of it. $10.00 per acre extra. maybe i will get a big yeild boost, and it will be a good mistake, but for now all i now for sure is the bill is way higher. what is reasonable way to handle this? guess i still remember a few years ago, when they charged me $2.00 per acre extra to add my own chemical to the spray tank. "

 Then a few posts later,,,,Gene has convinced himself he does owe for something he did not order.

"by law, if you take possession of it, you are required to pay. can't make you pay if you send it back. if you eat it, you owe for it. if you just let it set, you are still required to pay, as you breached you duty to mitigate damage."  (which is incorrect btw,, that only applies to a tangible object which can be returned. A chemical wrongly applied is NOT the same as being charged for an unordered part. The chemical can not be returned or refused unlike a equipment part which can be refused or returned after delivery.  So if the Dealer orders a new tractor in your name because you ordered a new part on your present tractor are you required to pay for the new tractor?  )

Then a dozen plus posts later.....

"i have a long term good relationship with coop. don't want to be thought of as an a-hole over this. heck, they even weigh back leftover seed beans for me. if it bumps my yield 3-4 bu, i don't want them to think i am trying to get something for nothing. since whole field was sprayed, there is no way to know it there was a yeild bump or not. has anyone used headline on beans? was there a marked yield bump? how was similar situations like this handled, with all parties satisfied? what is the hardline position for them and me? what was the results of that position? i guess i was looking for something i could use to help me make a decision on how to deal with them over this."

This is a perfect example of asking for a great answer,, without taking the effort to supply all the information to posters so they could determine what would be the best course of action, or give advice of what they did in a similar situation. 

 Considering all the "qualifiers" :

Gene continues to add on to any answers he is given.

He's already convinced himself he really does owe the co-op and has to pay for an application of a chemical which he never ordered.

There is no acceptable answer , pay the bill and move on.

(Remember the entire point was to do a test "strip" to determine if the chemical really did make a yeild improvement impossible once the entire field was done.)