Vol 117 (2004): Proceedings of the Florida State Horticultural Society

Purple nutsedge (Cyperus rotundus) control with drip-applied metam potassium

Bielinski M. Santos
University of Florida
Published December 1, 2004
  • cyperus rotundus,
  • weed control,
  • non-fumigant control


Over the years, recommendations on metam potassium (K-Pam®) rates and efficacy have been inconsistent. Many of these inconsistencies are due to the lack of knowledge about application techniques. Therefore, multiple field trials were conducted to determine: a) the effect of K-Pam water delivery volume on weed control, and b) the influence of K-Pam concentration on nutsedge (Cyperus rotundus L.) control. In the K-Pam and water volume trial, treatments were the untreated control, and six combinations of two K-Pam concentrations (3,000 and 6,000 ppm) and three water flow rates (28, 43, and 57 mL min[sup-]m [sup-]per row). The application rate was 570 L ha[sup-]. Results showed that all K-Pam treatments effectively controlled purple nutsedge, regardless of the flow rate or the concentration. In the K-Pam concentration plus rate study, treatments were the non-fumigated control, K-Pam at 285, 570 or 1,040 L ha [sup-] applied at 3,000 ppm, and K-Pam at 570, 1,040, and 2,080 L ha[sup-] applied as 6,000 ppm. Regardless of the rate and total water volume, applying 6,000 ppm was more effective on nutsedge than 3,000 ppm. Finally, in the K-Pam concentration study, a fixed rate of 570 L ha[sup-] was applied in concentrations of 1,000, 2,000, 3,000, 4,000, 5,000, and 6,000 ppm. Results indicated that at 10 weeks after treatment, nutsedge densities declined linearly as concentration increased (y = 290.57-0.0409x), and that K-Pam concentration was more important than water delivery volume.