By Mark Loux, Ohio State University Extension herbicide specialist
In general, 2012 offered many challenges to crop production, and herbicides were no exception. The lack of rain in the early part of the 2012 growing season reduced preemergence herbicide effectiveness, so some growers who had the right strategy in place still had problems. The reminder here is to stay with the right strategy and not to make many changes based on one year’s weather. The right strategy is an application of burndown and residual herbicides prior to crop emergence (omitting the turndown herbicides where the field is tilled), followed by the appropriate post emergence herbicide(s) based on weeds that are present and any knowledge of herbicide resistance in the field.
This should be supplemented with a relatively low-cost fall herbicide application to help with certain weeds — marestail, dandelion, poison hemlock, and winter annuals. It goes without saying, hopefully, that relying just on glyphosate for the burndown will usually not work, and growers should add 2,4-D, Sharpen, etc. to the preplant applications. It’s also important to realize the value of shifting from Roundup Ready (RR) to Liberty Link (LL) technology to either resolve resistance issues or just break the cycle of continuous glyphosate use.
The Dow Enlist trait is supposed to be available in corn in limited quantities in 2013, which provides the option of using 2,4-D on larger corn than is currently safe, and anytime around planting. The product that can legally be applied post emergence to this corn is Enlist Duo, Dow’s premix of glyphosate and 2,4-D. The trait has not been approved as of yet, though.