Diagnosing group C herbicide damage in field peas

This category contains root pre-emergent Group C herbicides such as simazine and metribuzin that are routinely used in lupins, but damage field peas. Cyanazine and metribuzin are registered for pre-emergent weed control in field peas.

Metribuzin damage. Typically scorched ends/edges of older leaves and tendrils
Plants become stunted with scorched brown leaves

What to look for

    Paddock

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

    Plant

  • Seedlings emerge normally but tips, edges of older leaflets and tendrils become bleached, pale brown and shrivelled.
  • Necrosis moves to successively younger leaves, as the plant becomes pale and stunted, until it recovers or dies.

Where did it come from?

  • 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.
  • Damage is more common on topsoils with low adsorption capacity such as sands with low organic matter.

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.

Further information

Pulses Australia [1]

Links
[1] http://www.pulseaus.com.au/

Source URL: https://www.agric.wa.gov.au/mycrop/diagnosing-group-c-herbicide-damage-field-peas
This print version was generated at 12:57am on the 11th of June, 2023.
The original document was last revised at Wed, 13/05/2015 - 2:06pm

Important disclaimer

The Chief Executive Officer of the Department of Primary Industries and Regional Development and the State of Western Australia accept no liability whatsoever by reason of negligence or otherwise arising from the use or release of this information or any part of it.