This data highly suggests that you must control weeds as they emerge. To wait and spray once weeds are up means a loss in yield.
This information means you have to use a pre-emerge herbicide on corn. Then, if you do not get rain in seven days, you need to use tillage to kill weeds at the “white” stage.
“I think all corn producers should consider a two pass weed control program,” Sikkema said. Similarly, I argue that growers must use a two pass weed control system.
When Sikkema looked at soybeans, he found that if you did not control weeds until the unifoliate stage you could lose six bu/ac. His research said you should keep soybeans weed free up to the second trifoliate.
Sikkema also showed data that demonstrated there was no difference in corn yield between Integrity, Converge, Primextra and Lumax (Dual + Atrazine + Callisto). These results, however, were with the specific weed spectrum he had in his fields. There are differences in specific weed control among these herbicides.
Sikkema presented this research at the South West Ag Conference (SWAC), held Jan. 4 to 5 at the Ridgetown Campus of the University of Guelph.