2017 Tips and Tactics: Reducing Herbicide Damage

Published: 10 Feb 2017

Key Points

  • Managing weeds in summer fallows conserves soil water for subsequent crops and reduces the weed seedbank for subsequent seasons.
  • Drift from the application of herbicides (and from Group I phenoxy herbicides in particular) has caused significant damage to crops in recent years.
  • Improved spraying practices are needed along with better understanding of and response to weather and other environmental conditions.
  • During summer across the northern grains region, there are only a limited number of hours when conditions are conducive for spraying with low drift risk.
  • 2,4-D amine formulations have relatively low volatility, meaning they are effectively non-volatile when used in accordance with label requirements. As such, the large majority of damage is likely to arise from spraying during local surface temperature inversion conditions and from incorrect boom setups.
  • In some cases symptoms and damage may be from roots taking up residual 2,4-D in the soil from previous applications.
  • While cotton is less sensitive to some other Group I herbicides when compared to 2,4-D, simply switching to these alternate Group I herbicides is unlikely to significantly mitigate risk. Attention must be given to the weather and other application factors involved.
  • Alternate herbicide options exist for key weed species (such as fleabane) where 2,4-D is currently being used. These include a range of pre- and
    post-emergent herbicides.

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Region: North