Fall Weed Management

Fall Weed Management

Fall is a critical time for vineyard weed management, especially for controlling pesky perennial weeds and pre-emergence of winter annuals. The following is some “timely” basic information on weeds and some specifics on management considerations in the fall.

• The 3 main types of weeds:
  • Annuals-plants that live for less than one year.
    • Winter annuals germinate in the late fall and winter, grow, and go to seed during the following spring and summer.
  • • Summer annuals germinate in the spring, grow, and go to seed during that spring and summer.
  • Biennials - Plants that live for more than one year, but less than two years, to complete the seed production cycle.
  • Perennials - Plants that live for more than two (2) years.
    • Can be herbaceous or woody.
       
• To ensure optimal efficacy of management tool, including herbicides, always remember:
  • Apply the management tool at the appropriate time to best control the specific weed.
  • For the best efficiency of mechanical management, try to get to the weed at the early seedling stage.
  • Always try to eliminate the weed BEFORE it goes to seed.
  • Match the correct herbicide to the specific weed pest.
  • Adjust the herbicide rate to the application timing and soil type.
  • Use the proper application technique and avoid drift or overspray.
  • Sprayer calibration is important with pre-emergence herbicides.
    • If you have been using a “Roundup only” program and haven’t calibrated it lately, be sure to do so before making the pre-emerge application.
       
• Perennial weeds such as Canada thistle, nutsedge, poison ivy, mulberry, and many perennial grasses are especially susceptible to glyphosate (Roundup) at this time of year.
  • Fall applications are very effective because these plants are strongly translocating down so they will take the herbicide to underground storage structures which will greatly improve their activity.
  • An application after grape leaf drop but while the weed foliage is still intact is ideal. Glyphosate can be absorbed by any green tissue, so waiting until grapevine leaf drop or the use of shielded sprayers is important. In any event, avoid contact with grape foliage or green stems or damage may occur. See labels for complete instructions.
  • Spring applications of glyphosate are less effective on most perennials since the movement of stored energy is upward and away from storage structures.
     
• This is also the time to include (tank mix) a pre-emergence herbicide with glyphosate.
  • A pre-emergence herbicide will control winter annual weeds (e.g. chickweed and henbit)
    • Residual grass herbicides include Devrinol, Gallery, Kerb, Prowl, Sinbar, Solicam, and Surflan.
      • Kerb, Sinbar, and Solicam may be used but only be on vineyards established 3 years.
    • Residual broadleaf herbicides include Casoron, Gallery, Goal, Karmex, Princep, Sinbar.
      • Casoron, Karmex, Princep, and Sinbar may be used but only be on vineyards established for 3 years.
    • Again, these are only meant as suggestions – always see labels for complete instructions.

Fall herbicide applications are the first step in a successful chemical weed management program. You can follow up in early spring to control the summer annual weed pressure.

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