Diagnosing group I herbicide damage in field peas

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

Young growth twists rapidly after herbicide application
New leaves and tendrils become grossly distorted
Phenoxy acid Pyridines
Chemical name Example trade name Chemical name Example trade name
2,4-D amine Amicide Advance® Clopyralid Lontrel®
2,4-D ester Estercide Xtra 680® Triclopyr Garlon®
MCPA amine Agritone 750® Fluroxypyr Starane®
MCPA ester LVE MCPA® Picloram

Tordon®, Grazon®

MCPB MCPB® Benzoic acids
2,4-db 2,4-DB®, Buttress® Dicamba Banvel®


What to look for


  • Severely distorted plants that gradually die or recover.
  • 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.


  • Rarely, herbicide residue damage causes poor emergence.
  • Plants rapidly develop distorted and twisted growth after spray contact.
  • Plants very slowly become pale necrotic then die.
  • Growing points are pale and distorted and may die.
  • Slightly affected plants can gradually recover.

Where to go for expert help

Page last updated: Monday, 15 June 2015 - 3:19pm