Oats are less susceptible to copper deficiency when compared to wheat and barley, however copper is essential for growth and development. Plants need Cu to produce new cells and for pollen development (sterile pollen), and hence Cu deficiency severely effects grain yield. Deficient plants that apparently look healthy can produce shrivelled grain reducing both grain yield and quality.
Tissue tests, using the youngest emerged leaf can help diagnose Cu deficiency. Tissue tests with Cu concentrations less than 1.3mg/kg indicate the plant is severely Cu deficient. Applying 3-9 kg/ha of copper sulphate (25% Cu) with fertiliser at seeding in areas suspected to be deficient in Cu correct the deficiency. Copper fertiliser has a long residual in the soil, and a single Cu application at recommended rates can last 20-30 years. Intermittent tissue testing of youngest leaves can maintain Cu at adequate levels.
Cu deficiency symptoms
Copper deficient crops have a patchy appearance with plants in poor areas stunted, pale green and looking limp and wilted even with ample soil water. Lat tillers may develop at notes or joints above round. Young leaves turn pale green while old leaves remain green. Under conditions of severe deficiency, plants may have leaves which die back from the tip and twist into curls.
The ears of Cu deficient plants are shrunken with gaps such as 'frosted heads'. The heads of Cu deficient plants have poor seed-set from sterile pollen thus resulting in 'white heads', similar to the ear heads affected by drought, heat stress and frost.
This information is from DAFWA bulletin 4798 'Growing oats in Western Australia for hay and grain', produced by Raj Malik, Blakely Paynter, Cindy Webster and Amelia McLarty, with additional input from Ross Brennan.