Khaki Weed (Alternanthera caracasana) is a perennial weed from tropical America that has invaded the southern U.S. at an alarming rate. Because it has a tremendous tap root, it is difficult to control in its mature stage. Repeated sprays and use of surfactant is necessary. Surfactants (spreader-stickers) break down the surface tension on the leaf and allows the herbicide to penetrate better and be more effective.

  • The best control is to not let the plant go to seed. If it does go to seed, pre-emergent control can be effective. The product Isoxaben has proven to be effective if applied in the early spring.
  • Trimec is a three-way herbicide that has Dicamba and two other selective post-emergent herbicides that won’t harm grass if applied according to directions. It works best on young plants just after they have emerged from the seed. It is best used in a lawn with no trees or ornamental plants nearby. (Fertilome Weed Out)
  • If ornamentals are present, a product with 2,4-D alone is probably the best way to go. Use of a surfactant will greatly increase the penetration and uptake of the herbicide. Again, it works best on young plants.
  • Glyphosate (Round Up) can be sprayed directly on the weed. Visible signs of yellowing will occur within 7 days, but do not disturb the weed for 2 weeks to allow time for the translocation of the chemical to the roots.
  • Because of its strong taproot, repeated sprays will be necessary, and will be most effective in the seedling stage.
  • Pre-emergent control is highly recommended. The product Isoxaben has proven to be effective if applied in the early spring.
  • Some reports of pouring a small amount of boiling water right in the center of the plant have been positive, if organic methods are desired. Labor seems to be the biggest issue!