Application of burndown plus residual herbicides in late April or close to planting (whenever that is). This accomplishes the goal of applying the residual later in the season, which increases the potential for adequate control of late-emerging marestail plants. The disadvantage to waiting this late, especially as applications are delayed into May, is increased variability in the burndown of existing plants.

This variability can be minimized by increasing burndown herbicide rates or by using a more effective mix of burndown herbicides. Some examples:

  1. Rates of Liberty can be increased from 29 to 36 oz./acre as the season progresses, along with the addition of a few ounces of metribuzin
  2. The three-way combination of Sharpen + glyphosate + 2,4-D ester may be more consistently effective than glyphosate + 2,4-D. Be cautious about the effectiveness of glyphosate plus 2,4-D alone once marestail plants have started stem elongation