As corn harvest gets rolling it is apparent there was a heavy flush of Palmer pigweed that emerged several weeks ago.
After the rain today on Aug. 3 there will likely be even more emerge.
Though no one wants to spend more money on drought stressed corn post-harvest, it well could pay off next spring in soybeans or cotton.
Good options to control this late flush of Palmer pigweed include tillage and the burndown herbicide Gramoxone (paraquat).
Please note if you elect to go with tillage that a disking will likely provide good control of smaller Palmer (<4”) but larger Palmer (>8”) will often re-root and grow back.
Likewise, Gramoxone will provide consistent control of smaller Palmer, but regrowth can happen with larger plants.
Residual herbicides should be considered as well with so much growing season left. Fall applied residual products like Valor, metribuzin and simazine would all be good choices here, depending upon what crop is to be planted next spring.
If the field is slated to go to wheat this fall then be cautious on utilizing a residual herbicide. Valor at the 1.5 to 2 ounces per acre rate maybe applied up to 30 days before wheat planting and would be the only real viable option for residual control prior to planting wheat.