Diagnosing Group I herbicide damage in canola

Group I herbicides are used for broadleaf summer weed control or selective broadleaf weed control in cereals. Damage can be caused by soil residues or spray contact.

Sprayed plants have thickened crowns, stems and petioles and twisted, distorted petioles and leaves
Twisted stems and curled, split pods from spray drift after flowering
Stem kinking and thickening in early (above) and late growth
Roots may develop nodules that can resemble club root

What to look for

    Paddock

  • Severely distorted plants
  • Direct spray damage is uniformly distributed but varies with spray coverage on overlaps or boom turns.
  • Spray drift damage is usually worse near the source, but ester vapour drift can cause widespread damage that can be apparently random due to swirling wind effects.

    Plant

  • Rarely, herbicide residue damage causes poor emergence.
  • Sprayed plants have thickened crown, stem and petiole and twisted, distorted petioles and leaves.
  • Downward bending of the crown, stem and petioles.
  • Crown swelling may become enlarged and cracked reducing sugar and nutrient flow to the plant, and pale new leaves.
  • After stem emergence, stems bend then grow up causing a kink,
  • Herbicide drift after stem elongation causes twisting of stems and pods. Pods may abort or curl and split.

Where did it come from?

Time of herbicide application
Time of herbicide application
Dry soil
Dry soil
Temperature
Temperature
  • The risk of spray drift is greater when there is a temperature inversion or windy conditions.
  • Germination damage is less likely with no-till sowing.
  • Herbicide breakdown in the soil is reduced when the soil is dry
  • Vapour drift of ester formulations can go for kilometres in warm conditions.

Further information

Department of Environment and Primary Industries Victoria - Avoiding crop damage from residual herbicides [1]
Department of Environment and Primary Industries Victoria - Spraying, spray drift and off target damage [2]
APVMA registered products data base [3]
GRDC fact sheet - In-crop herbicide use [4]
HerbiGuide [5]
Croplife Australia - Herbicide Mode of Action Table [6]

Links
[1] http://www.depi.vic.gov.au/agriculture-and-food/farm-management/chemical-use/agricultural-chemical-use/chemical-residues/managing-chemical-residues-in-crops-and-produce/avoiding-crop-damage-from-residual-herbicides
[2] http://www.depi.vic.gov.au/agriculture-and-food/farm-management/chemical-use/agricultural-chemical-use/spraying-spray-drift-and-off-target-damage
[3] https://portal.apvma.gov.au/pubcris
[4] http://www.grdc.com.au/GRDC-FS-InCropHerbicideUse
[5] http://www.herbiguide.com.au/
[6] http://www.croplife.org.au/downloadpdf.php?url=wp-content/uploads/2013/05/2014-Herbicide-MOA-Table.pdf

Source URL: https://www.agric.wa.gov.au/mycrop/diagnosing-group-i-herbicide-damage-canola
This print version was generated at 9:11pm on the 7th of May, 2024.
The original document was last revised at Mon, 15/06/2015 - 3:17pm

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Important disclaimer

The Chief Executive Officer of the Department of Primary Industries and Regional Development and the State of Western Australia accept no liability whatsoever by reason of negligence or otherwise arising from the use or release of this information or any part of it.