Diagnosing physiological leaf damage in wheat
A physiological condition associated with the presence of rust resistance genes in some wheat varieties that causes leaf damage. Yield impact is unknown.
What to look for
- Plants with apparent leaf disease that may look worse in poorer growth areas.
Paddock
- Symptoms usually appear as light flecking on younger leaves and become more severe on older leaves, appearing in spring near head emergence, but may be seen earlier or later.
- Symptoms vary according to seasonal weather conditions and plant vigour or nutrition.
- Nutrient sufficient lush wheat in cool moist growing conditions express pale flecks and blotches, then sunken yellow leaf tissue dotted with islands of healthy green tissue that develops dead lesions. Some blotches can have a streaky look. This condition can be referred to as non- pathogenic leaf blotch or "flame yellows".
- Leaves in poorer conditions, particularly low in nitrogen, die back from the tip and larger irregular dead lesions and or dead areas extending down the leaf or midrib.
- Plants may grow out of the symptoms as temperatures rise, although all leaves on the plant may be affected to some degree.
- A less damaging condition called "leaf tip necrosis" causes tip withering, often on the flag leaf.
Plant
What else could it be
| Condition | Similarities | Differences |
|---|---|---|
| Diagnosing yellow spot of wheat | Yellow spot also causes tan leaf lesions with yellow margins that lead to tip death | Yellow spot blotches are initially oval and spread before the leaf tip dies |
| Diagnosing septoria nodorum of wheat | Cause irregular leaf lesions with a yellow margins | Septoria nodorum form black fruiting bodies in the dead tissue |
| Diagnosing septoria tritici of wheat | Cause irregular leaf lesions with a yellow margins | Septoria tritici form black fruiting bodies in the dead tissue |
| Diagnosing potassium deficiency in wheat | Cause leaf death from the tip of older leaves | Potassium deficient plants are paler and often appear to be water stressed |
| Diagnosing false black chaff in wheat | Discolouration on the stem and head is another physiological condition | Caused in varieties with the Sr2 rust resistance gene (e.g. Carnamah, Mace). |
Where did it come from?
Susceptible varieties
- Physiological leaf damage in wheat is a genetically inherited trait that is triggered by environmental conditions and has been prevalent on variety Mace. Leaf tip necrosis, on the other hand, is another physiological condition which in known to be caused in varieties with the Lr34 or Yr18 rust resistance genes (e.g. Yitpi) and is also triggered by environmental conditions.
Management strategies
- No treatment as this is a physiological condition that does not respond to fungicide.
See also
Where to go for expert help
Page last updated: Thursday, 16 April 2015 - 10:04am