Manganese deficiency in barley is widespread but confined to small soil related patches that have declined as soils have acidified.
What to look for
Paddock
Patches of pale, floppy plants in an otherwise green healthy crop.
Deep gravel areas and recently limed paddocks are usually most affected.
Plant
Initially, middle leaves are affected first, but it can be difficult to determine which leaves are most affected as symptoms rapidly spread to other leaves and the growing point.
Leaves develop interveinal bleaching and/or white dead flecks.
Blotches develop that may have a thin brown rim.
Leaves often kink and collapse and eventually die.
Tillering is reduced with extensive leaf and tiller death. With extended deficiency, the plant may die.
Surviving plants produce fewer and smaller heads.
Where does it occur?
Soil type
Dry conditions
Soil ph
Deficiency tends to occur on coastal alkaline soils and high phosphorus retention index (PRI), water repellent gravels associated with wandoo powderbark wandoo, brown and blue mallet and blue mallee vegetation.
This occurs in an area south of Moora to Katanning and east from Corrigin to Dumbleyung, and infrequently on the Esperance sandplain and mallee area north of Esperance.
Manganese deficiency is worsened by dry soil, high soil pH, alkaline fertilisers and root pruning herbicides (particularly groups A and B).
Management strategies
Spraying foliar
Soil application
Foliar spray.
Acidifying ammonium nitrogen fertilisers can reduce manganese deficiency by lowering pH and making manganese more available to growing crops.
Manganese fertiliser is effective but expensive as high rates and several applications are required to generate residual value.
Seed manganese coating treatments have little effect in preventing deficiency.
How can it be monitored?
Tissue test
A whole-top plant test of 17mg/kg gives a rough indication of deficiency.
Use youngest emerged leaf to test for accurate manganese levels - with levels less than 15 ppm an indicator of manganese deficiency.
There is no reliable soil test for manganese.
Due to the poor correlation to yield, no critical concentrations can be determined.
