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!
Evidently the Khaki Weed (clover stickers) has taken over our fenced in large back yard. We have numerous trees and beautiful flowering plants (as well as the septic system) in this yard which is also where our dogs frequent. Could you recommend a product (other than Round-Up) to use to kill out that invasive spreading weed that won’t harm our pets or septic system? Thank you.
Khaki weed is difficult to control, even with chemical forms of herbicide. Organic methods will work better if they are timed correctly and applied correctly. An organic non-selective post-emergent option is: 1 gallon of 20% Horticultural Vinegar + 2 tablespoons orange oil + 2 tablespoons Dawn liquid.
Do not dilute the vinegar. This would need to be repeated many times on the new growth in the spring, as it is a “burn back” only control-it will not translocate to the roots and kill the roots. If you “burn back” enough times the plant cannot produce carbohydrates to survive.
Organic pre-emergent control for the seeds would be Corn Gluten, applied at the rate of at least 20#/1000 sq.ft. Corn gluten should be applied in early spring, just before the seeds are expected to germinate. It must be watered-in with 1/2″ of water, then NO WATER should be applied for at least 5 days. No irrigation, no rain. I hope this helps.