Figure 2. Emerging giant ragweed in a field near Clay Center. (Photo by Irvin Schleufer)
Developing a Successful Early Season Weed Management Program
Profitable crop production starts with a weed control program that includes pre-plant and/or pre-emergence herbicides to deliver long-lasting, residual weed control. A spring burndown program in corn and soybean provides effective weed control to prepare for planting and helps to decrease the seedbank during the season. Early season weed competition can greatly reduce yields and profits.
Burndown
Several studies have shown that if weeds grow to 9 inches, soybean yield can be reduced by as much as 6%; 12-inch weeds can result in up to a 10% yield loss. In corn, 12-inch weeds could cause 22% yield loss when left uncontrolled.
Among the herbicides registered for spring burndown weed control are:
- Corn: 2,4-D*, Aim, atrazine, Balance Flexx, Corvus, dicamba, glyphosate, Landmaster II, Lexar EZ, and Sharpen
- Soybean: 2,4-D* (use esters only), Authority First, glyphosate, Gramoxone, Pursuit, and Sharpen
*If 2,4-D is applied at 16 fl oz/acre in a burndown program, the preplanting interval is seven days for corn and soybean; if 2,4-D is applied at a rate above 16 fl oz/acre in a burndown program, the planting interval should be 14 days for corn and 30 days for soybean.
Pre-emergence
The pre-emergence (residual) herbicide protects the crop with early, effective, and lasting weed control to help maximize yields, regardless of the production system. In addition, including pre-emergence herbicides can minimize the post-emergence herbicide applications and protect against early-season weed competition when weather or busy schedules prohibit a timely post-emergence application. Among the herbicides registered for pre-emergence weed control are:
- Corn: Aatrex, Balance Flexx, Corvus, Degree Extra, Fierce, Lumax EZ, Outlook, Surestart, Tripleflex, and Zemax
- Soybeans: Authority MTZ, Boundry, Command, Dual II Magnum, Envive, Optill, Pursuit, Prowl H2O, Valor XLT, and Warrant
Always read and follow herbicide label directions.
Source : unl.edu