Last year we did some plots with Asana and Headline and is some plots we did see up to a 10 bpa advantage when there was no evidence of any problem when we sprayed and there was no reason to spray the rest of the fields. In other fields of the same variety planted and sprayed the same day within two miles of each other there was little or no yield difference in our plots. I've seen quite a bit of data showing that a preventitive treatment of a fungicide and insecticide can pay in soybeans but it's very difficult to know exactly where that yield increase came from when the fields never showed any evidence of a problem.

This picture is of one of our bean fields last year where the right hand half was treated with a fungicide and insecticide while the left hand side was not.  I think in this field there was a 4-5 bpa advantage to the treated side by as you can see the treated side matured slower, our guess is that it was healthier so the plants didn't die off as fast but we could never find any signs of disease or insect pressure that might have caused problems in the un-treated part.