| Triazines | Triazinones | ||
| Chemical name | Example trade name | Chemcial name | Example trade name |
| Simazine | Simazine | Metribuzin | Sencor |
| Geasatop | Lexone | ||
| Atrazine | Atrazine | ||
| Bladex 2 | |||
| Ureas | |||
| Diuron | Diuron | ||
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.
What to look for
- Pale and scorched seedlings with worse damage on sandier soils with low organic matter.
Paddock
- 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.
Plant
What else could it be
| Condition | Similarities | Differences |
|---|---|---|
| Diagnosing seedling root rot in field peas | Progressive necrosis and death of older leaves | Necrotic discoloured roots |
| Diagnosing zinc deficiency in field peas | Older leaf pale necrosis. | Plants are less stunted have more inter-plant variability, and do not die. |
| Diagnosing potassium deficiency in field peas | Older leaf pale necrosis. | Pinkish necrotic spots rather than marginal necrosis; affects older plants |
| Diagnosing soil acidity in field peas | Older leaf pale necrosis. | Affects leaf patches rather than margins and is worse on usually lighter textured acidic soils. Roots are also stunted. |
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.
See also
Further information
Page last updated: Wednesday, 13 May 2015 - 2:06pm