Group A Herbicides in Fallow

Published: 1 Oct 2019

Using Group A herbicides for control of grass weeds in fallow

With the increasing frequency of glyphosate resistance, growers require alternative solutions to control grass weeds in fallow. The use of Group A herbicides in fallow to control grass weeds such as the Chloris species – feathertop Rhodes grass (Chloris virgata) and windmill grass (Chloris truncata) – has shown to be a viable option for controlling young weeds. However, Group A herbicides have a high frequency of resistant individuals in unselected populations, so will quickly develop resistance if survivors are not controlled.

Key Points

  • Target weeds up to the early tillering growth stage only.
  • Ensure weeds are fresh and actively growing.
  • Medium to medium-coarse droplet spectrum. Minimum water rates of 50 to 70L/ha; higher water rates should be considered in heavy stubble conditions.
  • One application per fallow, targeted at the main spring flush.
  • Always follow up with a double knock after approximately seven days. Ensure all survivors are controlled.
  • Apply the second spray in a double-knock program in the opposite direction to the first.
  • Avoid tank mixing where possible. Consider adding required tank mix herbicides to the second knock.
  • Consider rotational constraints before planting cereals, sorghum or maize into treated areas.

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Region: North

GRDC Project Code: ICN1307-001RTX, ICN1811-001SAX,