Palmer Amaranth Control With Mixtures Peanut Notes No. 60 2018
Keep in mind that many fields contain Palmer amaranth that is resistant to ALS-inhibiting herbicides. I assume that some fraction of every field has resistance to Cadre or Impose. These herbicides are used to control many weeds and they are a good option as long as carryover potential is considered. But they do not stand alone because of resistance. A good program is Cadre or Impose at the recommended rate plus either Cobra at 8 oz/acre or Ultra Blazer at 16 oz/acre. The application should target Palmer amaranth that is 3 inches or less. It is a challenge to be this timely. When the combination above is applied to weeds that are 4 inches are taller (most of the time) increase the rate of the PPO-inhibiting herbicides to 12 and 24 oz/acre, respectively. Keep in mind that when Palmer amaranth gets above 4-5 inches effectiveness goes way down with these herbicides. I suggest 1 quart per 100 gal spray solution of nonionic surfactant (80/20 blend). Other products, including crop oil concentrate, may appear to work more quickly and better, but at the end of the day the control will be about the same regardless of spray adjuvant. Slower ground speeds and more water per acre will improve consistency of control. With these mixtures I would leave out the 2,4-DB. That might be needed later in the season.