Pointers for Better Pre-emergent Herbicide Performance

Josh McGillCitrus Expo, weeds

Ramdas Kanissery, speaking at the Citrus & Specialty Crop Expo, offered what he called an important strategy to prevent weed outbreaks in groves: “Never let ’em germinate.” Growers can keep weeds from germinating with pre-emergent herbicide programs, said the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) assistant professor of weed science. He works at the Southwest Florida Research and Education Center near Immokalee.

Pre-emergent Herbicide

Kanissery’s tips for improving pre-emergent herbicide efficiency include:

  • Applying residual herbicides to bare soil to ensure maximum soil incorporation
  • Turning on irrigation to activate the residual herbicides in soil
  • Using a compatible post-emergent tank-mix partner if there is minimal weed growth and rotating post-emergent tank-mix partners.

The weed scientist also urged growers to consider tank-mixing pre-emergent herbicides with different modes of action to increase the spectrum of weed control and to reduce tolerance/resistance issues. He suggested they consider utilizing adjuvants for improving the efficacy of pre-emergent herbicides.

For tree safety, Kanissery suggested avoiding spray contact with foliage and fruit. He also suggested that growers have the right spray boom height, have the optimal off-center nozzle angle and maintain optimal spray pressure.

Kanissery listed the major pre-emergent herbicides used in Florida citrus by active ingredient and brand name:

  • Simazine (Princep Caliber 90)
  • Diuron (Direx and Karmex)
  • Norflurazon (Solicam)
  • Pendimethalin (Prowl)
  • Indaziflam (Alion)
  • Flumioxazin (Chateau)

Citrus grove soils are persistent “seed banks” for weeds, Kanissery stated. He said suppression of the seed bank is important to prevent future weed problems.

Long-term suppression of weeds is a major challenge because weeds come up quickly in groves, Kanissery said. He added that scouting and understanding weed pressure helps with pre-emergent herbicide selection.

See Kanissery’s full presentation, which provides much more in-depth information, here.

About the Author

Ernie Neff

Senior Correspondent at Large

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