Diagnosing copper deficiency in barley
Most soils in Western Australia were copper deficient in their natural state. Copper is essential for pollen formation and has a role in formation of chlorophyll and lignification (cell wall strength). Deficiency causes sterile pollen, which, in turn causes poor grain formation and high yield losses.
What to look for
- Before head emergence deficiency shows as areas of pale, wilted plants with dying new leaves in an otherwise green healthy crop.
- After head emergence mildly affected areas have disorganised wavy heads. Severe patches have white heads and discoloured late maturing plants.
- Symptoms are often worse on sandy or gravelly soils, where root pruning herbicides have been applied and recently limed paddocks.
- Youngest growth is affected first and most severely.
- The first sign of copper deficiency before flowering is growing point death and tip withering, and/or bleaching and twisting of up to half the length of young leaves.
- The base of the leaf can remain green.
- Old leaves remain green and seemingly healthy.
- Tiller production may increase but they die prematurely.
- Heads may be white and withered or have a rat-tail appearance.
- Maturity is delayed and very late tillers may be present.
- Stems are weaker, although in less severe plants heads may be more erect. Severely deficient plants have few immature heads on weak and dirty stems.
What else could it be
|Diagnosing molybdenum deficiency in cereals||White heads and shrivelled grain||The main difference is that molydenum deficiency affects middle leaves first rather than the youngest leaf|
|Diagnosing calcium deficiency in barley||Youngest leaf twisting and death||Calcium deficient plants are dark green rather than light green and fewer small heads rather than white heads|
|Diagnosing stem and head frost damage in cereals||White heads, shrivelled grain, late tillers and delayed maturity||Spring frost does not cause death or twisting of the flag leaf, and is worse in frost-prone areas|
|Diagnosing take-all in cereals||White heads and shrivelled grain||Take-all causes blackened roots and crowns, often killing plants|
Where does it occur?
- With the exception of loam or clay salmon gum or York-gum soils, most soils required copper and zinc when cleared for agriculture.
- Copper persists in soil but is relatively immobile and can become unavailable to crops in dry soil particularly in no-till systems.
- Copper deficiency can be induced by heavy liming; increased plant nitrogen status; use of zinc fertiliser; and use of root-pruning herbicides, particularly groups A and B.
- Foliar spray (only effective in the current season) or drilled soil fertiliser.
- Copper foliar sprays are not effective after flowering as sufficient copper is required pre-flowering for fertile pollen development.
- As copper is immobile in the soil, topdressing is of little value, only being effective when the topsoil is wet.
- Mixing copper throughout the topsoil makes it more likely that roots can intercept the nutrient because soil at depth stays moist longer.
- In long term no-till paddocks fertiliser use via in-furrow application or seed treatment reduces the risk of plant roots not being able to obtain enough copper in dry seasons.
- Copper seed treatment is insufficient to for plant requirement in the current season.
How can it be monitored?
- DTPA soil test and whole top plant test provide a rough guide for copper status.
- Use youngest emerged leaf to tissue test for copper levels with levels less than 1.6 milligrams per kilogram (mg/kg) indicating copper deficiency.
- Copper deficiency may be confirmed by grain test after sampling affected heads containing grain and unaffected heads from the crop.