Controlling Weeds in Nursery and Landscape Plantings

Bulletin 867

Postemergence Herbicides

• Nonselective, translocated herbicides that are absorbed through the foliage and translocated throughout the plants, killing the tops and roots:
  Roundup Pro, Accord, Glyfos, Rodeo
  Touchdown
  

• Nonselective, contact herbicides that provide quick kill of the foliage of weeds but do not kill underground parts of perennial weeds:
  Finale
  Reward
  Scythe
  

• Selective herbicides that control grasses but not broadleaved weeds:
  Acclaim Extra
  Envoy, Prism
  Fusilade II, Ornamec
  Vantage
  

• Selective herbicides that control broadleaved weeds but not grasses:
  Basagran T/O
  Garlon 3A and 4E
  Stinger
  

• Selective herbicides that control nutsedge:
  Basagran T/O
  Manage
  

• Selective herbicide that controls moss:
  DeMoss
  

The following observations are relevant to any of the postemergence herbicides that are absorbed by foliage and translocated throughout the plant:

1. Intact foliage is needed to absorb the chemical, and intact foliage and root systems are needed for complete translocation. Do not mow or cultivate for at least 2 weeks prior to application or 5 to 7 days following application.

2. Healthy, actively growing weeds are controlled faster and more thoroughly than plants under stress from drought or pest problems. Injury symptoms from contact herbicides develop quickly (from hours to a day or two). Injury symptoms from the translocated products may take 7 to 14 days to develop.

3. Some postemergence herbicides in the following list have very little soil activity. Planting can follow application by 3 to 5 days. Though the symptoms of injury from the translocated herbicides develop slowly, once the herbicides have had time to move into weed roots, the soil may be worked. See Appendix II for postemergence herbicides that may be used just prior to reseeding.

4. Control of perennial weeds requires higher rates of application than control of annual weeds.

5. A surfactant may be needed to improve coverage of the foliage and absorption into the weeds. Some products include surfactant with them; for others one must be added. A typical amount would be 0.25% v/v (volume to volume). To make a 0.25% solution, add 2 teaspoons to 1 gallon or 1 pint to 50 gallons. The exact amount to add will vary with the brand of the surfactant. Read the label of the surfactant to determine the exact amount needed.

Canada thistle is a perennial weed that is difficult to control once it infests landscape beds.