With corn harvest under way, now is the time to think about postharvest weed control. Just this past year some of the worst glyphosate-resistant Palmer infested soybean and cotton fields in Tennessee were in corn the previous year. In most cases the Palmer amaranth that produced the seed emerged late as the corn was drying down. Often the worst Palmer patches come up in July in partially drowned out areas in a given corn field.
Palmer that emerges in July in these areas is often 3 to 4’ tall by harvest time and will easily produce thousands of Palmer seed that will be a problem next year. Just in the last couple of days driving by cut cornfields one can already see tall Palmer in patches in the cut stalks. Applying Gramoxone at 48 ozs now should control these pigweeds and limit the amount of seed they produce. If the soil is moist, consider adding a residual as well. Tankmixing in 1 oz of Valor or 5 oz of Verdict should provide enough residual to get to colder weather.