Integrated Crop Management is published by the Department of Entomology , Iowa State University , Ames, Iowa. Due to the wet conditions, weeds will likely have emerged prior to herbicide application. Early preplant applications will not be effective unless a burndown herbicide is included. Preemergence applications will also need a burndown herbicide in most instances. If only broadleaf weeds are present, treatments that include a triazine herbicide, 2,4-D or Banvel will provide acceptable control.
Triazines also have some activity on small grass.
The inclusion of a surfactant, crop oil concentrate and using liquid nitrogen will improve the activity of cyanazine and atrazine. When grasses are larger or the predominant vegetation in the field, more consistent control will be obtained with a nonselective herbicide such as Gramoxone Extra or Roundup. These herbicides can be tank-mixed with residual herbicides to improve control. Nonselective treatments are typically used in soybeans. Due to the later planting dates, weeds are often larger than found in corn production.