I need to take volunteer peas and canola out of wheat, which is currently at  4 leaf stage. 

Problem is, its on ground I don't own, and where onions will likely be grown under a pivot in 12 months time, so I have to be very careful of any possible residual problems.  It is also  relatively high pH.      Any sulphonyl urea herbicides,  or  Lontrel (clopyralid )  are definitely  out of the question.  

I  don't know what the  Dicamba story really  is regarding this issue, but have been told that some of the horticultural boys won't allow Dicamba on their ground, and some don't care.  

I sure can't afford to risk damaging a  pivot of onions... 

Any thoughts..?