Iron deficiency is rare but can be a problem in high-rainfall areas on peaty or calcareous soils, or after heavy lime application on most soils.
What to look for
Paddock
Pale plants particularly in waterlogged or limed areas.
Plant
Youngest growth is affected first and most severely.
Symptoms begin with young leaves turning pale green or yellow.
Inter-veinal areas become yellow and in severely deficient plants the inter-veinal area turns almost white.
New growth remains yellow for some time before leaves start to die.
Old leaves remain pale green and apparently healthy.
Severely affected plants are stunted with thin spindly stems.
Where does it occur?
Wet conditions
Iron deficiency can occur in highly calcareous or limed soils, particularly in cold and wet conditions.
Symptoms on heavily limed paddocks are transient and restricted to the season in which the lime has been applied.
Management strategies
Spraying foliar
No yield responses to iron to justify soil application.
Where symptoms occur, particularly in cold and wet conditions, they are frequently eliminated by increased soil and air temperatures.
Foliar sprays will remove the symptoms where they occur in highly calcareous or limed soils.
How can it be monitored?
Tissue test
Use whole-tops for plant testing and compare iron level between affected and unaffected plants.
The critical concentration for youngest emerged blade and whole shoot hasn't been determined for Australian grown cereals. However greater than 50 milligrams per kilogram (mg/kg) at the boot stage appears to be adequate for growth.
