Diagnosing group K herbicide damage in cereals

This pre-emergent herbicide group is used to control annual grasses and broadleaf weeds. It is applied to the soil either before or directly after sowing and prior to weed emergence. Symptoms appear as the crop emerges. In most cases weeds do not appear.

Burst coleoptile in metalochlor damaged wheat
Range of symptoms in metalochlor affected wheat
Stunted Dual Gold® affected barley with twisted leaves.
Chemical name Example trade name
Amides
Metalochor

Dual Gold®

Pyroxafulfone

Sakura®

 

What to look for

    Paddock

  • Poor or intermittent emergence that is often worse on light soil or varies between drill rows.

    Plant

  • Seed germinates but plants fail to emerge.
  • Malformed and twisted seedlings.
  • Leaves tightly rolled and do not unroll normally.

What else could it be

Condition Similarities Differences
Diagnosing groups D J herbicide damage in cereals Variable emergence, weak seedlings. Group K herbicide damaged plants do not have thickened coleoptiles or stubby thickened roots.
Diagnosing poor seed-soil contact in crops Variable emergence, weak seedlings. Poor seed-soil contact is more common in dense stubble and on heavy or very cloddy soil.
Diagnosing allelopathy in cereals Variable emergence, weak seedlings. Silly seedling plants remain spindly and have weak thin roots.
Diagnosing group C herbicide damage in cereals Seedling death may occur in rows and on sandy, low organic matter soils. Group C herbicide damaged plants bleach and die back from oldest leaves. Leaves may also have interveinal chlorosis.

Where did it come from?

Herbicide treated soil
Herbicide treated soil
Low organic matter
Low organic matter
  • Seed sown into herbicide-treated soil layer.
  • Light-textured soils with low organic matter.
  • Crop stressed by dry soil, waterlogging, lack of nutrients, disease or frost within 10 days of seeding.

Management strategies

  • There is no treatment available. Preventative measures include ensuring soil throw on the inter-row whilst maintaining a seed furrow free from herbicide.

See also

Where to go for expert help

Page last updated: Wednesday, 4 February 2015 - 12:07pm