Cover Crop Tips

Burndown & Control of Annual Ryegrass and Weed Control Tips

Annual ryegrass should be killed before it reaches the joint stage (this will vary depending on the date planted, amount of fall growth and winter and early spring weather). Spraying can be delayed until after jointing under warm weather conditions. Annual ryegrass can be a challenge to burndown if the burndown herbicide is applied at a time when there is cool, wet and cloudy weather. Spraying should typically occur when the annual ryegrass is 6-9” tall.


  • Daytime temperatures in 50’s and night time temperature in the 40’s are needed for decent translocation of glyphosate.
  • The desired burndown may not be achieved if daytime temperatures are in the 40’s and night time temperatures are consistently below the mid 30’s.
  • With these temperatures it may take 3-4 weeks and a second application for a complete kill.
  • One night of mid 30’s should not drastically affect performance.
  • Cloudy and wet weather may further slow glyphosate translocation.
  • Every weed species is different in the glyphosate translocation/temperature interaction.

Time of Application:

  • If night time temperatures are in the 30’s or low 40’s, spraying before 2pm will allow additional time for translocation. The timing of spraying is not an exact science but generally the more time for translocation, the more effective the burndown.
  • Allowing 4-5 hours of sunlight after spraying improves translocation if night time temperatures are expected below the mid30’s. A second burndown application is frequently needed to kill annual ryegrass with cool weather conditions

Application Rate:

  • Glyphosate – use full label rate of 44 oz/ac (check glyphosate formulation for labeled rate)
  • Add 8oz/ac of 2,4-D to help control winter annuals
  • Carrier – only apply 7-10 gals/ac with cold conditions; applying 15 to 20 gal/ac dilutes the glyphosate and reduces performance (compounded with cool temperatures); apply 15 gals/acre with warmer temperatures
  • Adding AMS or citric acid to adjust the water’s pH is critical for expected results
  • May want to add 0.25% more surfactant if using generic glyphosate
  • Adding crop oil decreases glyphosate uptake

Other Herbicides:

  • Simazine can be added to the glyphosate tank mix
  • Simazine requires 4” of rainfall to be fully activated
  • Simazine is absorbed by the new shoots and prevents them from growing
  • Atrazine or 28% should not be added to the tank mix (these products cause leaf burn and reduce glyphosate absorption) unless temperatures are warm.
  • Atrazine can be applied 14-21 days after glyphosate application at a rate of 2-2 1/2 lbs/ac plus cop oil (atrazine needs 2” of rainfall to activate)


  • Flat fan nozzles should be used at 20-40 psi
  • DO NOT use flood jet nozzles
  • Do not use an air induction sprayer
  • Excessive boom bounce can cause improper overlap and result in “streaks.”


  • Water should be free of any clay particles (pond water) as it will tie up the glyphosate.
  • A softening agent may enhance performance if hard water is being used.

Tips for Using Gramoxone as a Burndown:

  • Provides quicker burndown but is not translocated
  • Apply at 30-40 psi and with 20-40 gal/ac of carrier using flat fan nozzles
    • Higher volume is needed for taller annual ryegrass
    • Use clean water as a carrier that is free of clay particles.
    • 28% N or other clear liquid fertilizer can be used as a carrier
  • Add nonionic surfactant
  • Simazine or atrazine added to the tank mix reduces uptake and results in slower kill.
  • Add crop oil to mixture.
  • Adding 8 oz/ac of 2,4-D helps kill winter annuals

Order of Mixing:

  • Fill spray tank ½ full of carrier
  • Begin tank agitation and continue while mixing and spraying.
  • Add any dry and then liquid formulations.
  • Add either Glyphosate or Gramoxone to tank
  • Then add nonionic surfactant
  • Fill remainder of tank

Post Applied Options:

  • If glyphosate tolerant crops were planted, wait until there is 2-4” of annual ryegrass regrowth before spraying
  • Conventional corn options – Annual ryegrass should be less than 6” in height and temperature 70 degrees
      • Atrazine (2 to 21/2 lb/ac) and crop oil
      • Steadfast – 3/4 oz/ac, include adjuvant, 28%, Crop oil concentrate,  15 gal/ac water;  20-40 psi with flat fan nozzles
      • Option – 1.5 oz/ac; include adjuvant, 28%, yellowing of corn may occur; use of organophosphate insecticide may increase crop injury -see label
      • Accent – 2/3 oz/ac; can be used on bigger corn; include adjuvant,
        28%, Crop oil concentrate

Mention of any product does not constitute any type of endorsement or guarantee.