Managing Clearfield residues and plant backs this year


Managing Clearfield residues and plant backs this year

Clearfield® (imidazolinone) herbicides such as Midas and Intervix® are residual herbicides that may carry over from one year to the next. Particularly after a dry period, it is vital that growers take adequate precautions to prevent any potential effect in the following crop.

Following are a few points to consider when planning for the 2013 season:

  • Plantback crop selectivity is essential to minimise potential crop effect.
  • Rainfall, soil microbes and time are all key influencers of herbicide breakdown. Conditions need to be monitored after herbicide application and prior to sowing of the plantback crop to be able to select the most appropriate fallow crop.
  • One summer thunderstorm is not sufficient for the breakdown of Clearfield herbicides, particularly if hot, dry conditions prevail after the rain. Five rainfall events of 20mm fortnightly is a much better scenario than a one-off rainfall event of 100mm.

Plantback options

To work out what crop can be sown after using a Clearfield herbicide:

  1. Determine the date of herbicide application.
  2. Quantify the rainfall from the date of application up until sowing the plantback crop (excluding one-off rainfall events during summer).
  3. Consult product label recommendations on the Crop Care website.

Crop selection






Crop type


CLF JNZ wheat

CLF STL wheat

Clearfield canola

Previous crops

Faba beans

Field peas

Previous crops



Field peas

Previous crops






  • A minimum 8-month period applies.
  • Barley and Durum wheat varieties are more susceptible to Imidazolinone damage than bread/noodle wheat varieties and triticale.

Managing Clearfield residues

When sowing a plantback crop at the lower end of its plantback range, ensure the following steps are taken to help minimise potential follow crop damage as a result of imidazolinone herbicide residual:

  1. Root disease test – crop effect will be magnified in the presence of root disease.
  2. Apply zinc to the seed – allowing for early root development.
  3. Delay seeding – to maximise potential breakdown.
  4. Sow at the right depth to ensure adequate nutrition to promote rapid germination and emergence.
  5. Do not use another Group B herbicide in the plant back crop to avoid the potential of compounding herbicide effects.
  6. Avoid stress during the growing season. Any stresses encountered during the growing season may also exhibit symptoms (such as poor growing conditions, insect damage).

Sourced from Nufarm Specnote

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