Question: What was the most popular POST herbicide program for corn in Iowa Crop Reporting Districts 1 and 2 (NW and NC Iowa) in 1985?
Answer: 2,4-D + Banvel (dicamba), with 78 and 64% of the acres treated, respectively.
Every time I see an advertisement stating how the new HR traits provide new options for weed management I think it is good to remember the past. Granted, the traits allow 2,4-D and dicamba to be used at higher rates than were used in the past, but they are the same products.
In southern Iowa less than 15% of corn acres were treated with 2,4-D + Banvel in 1985. Why the big difference? The lack of high pH soils in southern Iowa allowed farmers to use high rates of atrazine and avoid the crop injury and off-target movement risks associated with the Group 4 herbicides.
Source: Wintersteen, W. and B. Hartzler. 1987. Pesticides used in Iowa crop production in 1985. ISU. Pm-1288.