Iron (Fe) deficiency is often seen on highly calcareous soils in the Esperance mallee, particularly in late July when soil temperatures are low and there is excess water in the soil.
What to look for
Paddock
Deficiency is most likely on soils with free lime, often in patches or wheeltracks where waterlogging is worse.
Despite being chlorotic, leaves remain relatively healthy and recover completely with the return of warmer drier weather.
Plant
Plants with pale green to intense yellow new leaves that contrast with healthy green old leaves.
Where did it come from?
Soil ph
There are a complex series of interactions in the soil that combine to reduce the availability of iron to plants. The deficiency will usually occur in plants grown on soils with a pH above 7.0 if the soil aeration is reduced slightly and temperatures are cold.
Management strategies
No yield responses to iron have been measured in the field 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, but there is no yield benefit.
