Broad constraint resources are outlined in the Agronomists Toolkit. Specific constraint categories are listed below:


Group B herbicide damage

Constraint - Group B herbicide damage


  • Seedlings emerge with discoloured thickened petioles and small cotyledons 

  • Distorted or cupped emerging leaves develop small elongated blades with elongated petioles

  •  Multiple new growing points produce bunchy narrow distorted leaves

  • Spray-affected plants stop growing and develop leaf spotting and crinkling with dead spots

  • Mildly affected sprayed plants develop shortened internodes

  • severe damage causes flowering stem death and plants repeatedly send up flowering side branches that also die until the plant dies

  • Purple discolouration appears on the sunny side of stems


  • Group B's are highly toxic to canola, and can cause death or increase sensitivity to stress

  • Yield can be severely decreased


There is no treatment. Plants will either die or recover. Management options include spraying when the risk of drift is low, following instructions on the label very carefully, keeping accurate records, and optimising growing conditions to reduce stresses.

Links and Resources

PDF BCG - Group B carry over

4 page PDF. Summary of trial, why it was conducted, how it was conducted, results, group B herbicides, group C herbicides, and commercial practice.

File size: 66kb
DAFWA - Diagnosing group B herbicide damage

Introduction, herbicides, what to look for in paddock and plant, what else it could be, where did it come from, and monitoring. Page last updated 2014.

File size: 66kb