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


Group I herbicide damage

Constraint - Group I herbicide damage 


  • Sprayed plants have thickened crown, stem and petioles 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

  • After stem emergence, stems bend then grow up causing a kink

  •  Pods may abort or curl and split


  • If rate is high, yield penalty may occur


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, optimising growing conditions to reduce stresses, and becoming familiar with the possible residual effects of different herbicide groups on different crops.

Links and Resources

DAFWA - Diagnosing group I herbicide damage

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