Mark VanGessel, Extension Weed Specialist; mjv@udel.edu
From the questions and comments I have been getting, there is a real effort to stay after the Palmer amaranth in fields. However, driving around it seems some of the patches on field edges are being neglected. If these plants are allowed to product seed, they will contribute to problems next year. Palmer amaranth is only beginning to flower, so if these plants are sprayed now, mowed, or pulled now, seed production will be eliminated. However, in only a couple of short weeks, those plants could potentially have viable seed. So be sure to control Palmer before the plants have a chance to produce seed.
I mentioned mowing for field edges. A single mowing now is not likely to kill those plants. Therefore, if mowing is your option to control them now, the site will need additionally mowing to keep these plants from producing seed. I do not know how many times you will need to mow them, but I suspect they will need to be mowed every 2 to 3 weeks to stop or minimize seed production.