Diagnosing group C herbicide damage in narrow-leafed lupins

This category contains root pre-emergent Group C herbicides such as simazine and metribuzin that are routinely used in lupins. Post-emergent atrazine damages lupins.

Necrotic leaf tips are rolled and fold in a claw shape
Oldest growth is affected first and worst
Plants look pale and stunted
Seedling death from post-emergent atrazine spray (unsprayed on right)
Triazines Triazinones Ureas
Chemical name Example trade name Chemical name Example trade name Chemical name Example trade name

Simazine

Simazine®

Metribuzin

Sencor®

Diuron

Diuron®

 

Geasatop®

 

Lexone®

   

Atrazine

Atrazine®

       

 

What to look for

    Paddock

  • Pale and scorched seedlings with worse damage on sandy soils with low organic matter.

    Plant

  • Seedlings emerge normally but tips of leaflets roll turn ivory coloured and shrivel. Necrosis progresses down the leaflet as the leaf develops a claw shape.
  • Necrosis moves to successively younger leaves, as the plant becomes pale and stunted, until it recovers or dies.

Where does it occur?

Spraying herbicide
Spraying herbicide
  • These herbicides are more active in moist soil.
  • Situations where the herbicide is close to seed. This includes shallow sowing or heavy rain washing herbicide into furrows in ridged seedbeds.
  • Topsoils with low adsorption capacity such as sands with low organic matter.

Management strategies

  • No treatment - the plant becomes pale and stunted, until it recovers or dies.

How can it be monitored?

  • It is important to observe withholding periods for these herbicides to avoid damage to following crops.
  • Take care when spraying not to spray non-tolerant varieties.

Where to go for expert help

Page last updated: Thursday, 5 February 2015 - 3:03pm