The issue we appear to have had this year, was when multiple chemicals 
are used.  Likely roundup with a cut worm pesticide according to a 
couple people I've talked to.  This is done to kill the weeds in the 
field when planting no-till.
This becomes an issue of the weeds are blooming and bees are visiting 
the flowers.   They come in contact with the pesticide on the weeds 
before the roundup has a chance to even make the weeds wilt.   If the 
beekeepers had been given notice, they could screen them in for a day or 
two until the roundup makes the flowers wilt enough that the bees would 
no longer be interested.

-Tim

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