Applying soil-residual herbicides with non-residual, foliar-applied herbicides can help reduce additional weed emergence following application and, therefore, reduce the need for another application later. The “lateness” of this year’s soybean crop undoubtedly will decrease the number of acres where layered residuals are applied, but nonetheless keep in mind that labels for most soil-residual herbicides used in foliar applications include soybean growth stages or time intervals beyond which applications cannot be made. Additionally, these labels include time intervals for rotational crops, such as wheat. A partial listing of soil-residual herbicides sometimes applied postemergence in soybean is presented in Table 1. Be sure to consult the label of any product used to determine maximum crop growth stage and rotational crop intervals.
Table 1. Maximum soybean growth stage and wheat rotation interval for several soil-residual herbicides that can be applied postemergence in soybean.
Product Maximum soybean growth stage Wheat rotational interval
Anthem Maxx Apply through third trifoliolate 1 month at up to 3.25 ounces
Dual Magnum At least 90 days before harvest 4.5 months
FirstRate Prior to R2 4 months
Outlook Fifth trifoliolate 4 months
Prefix At least 90 days before harvest 4.5 months
Warrant Before soybean reach R2 4 months
Warrant Ultra Before soybean reach R2 4 months
Zidua SC Sixth trifoliolate 1 month at up to 3.25 fluid ounces