To establish the occurrence of boron toxicity in barley crops in South Australia.

• Barley crops showing foliar symptoms of a disorder recognised as boron toxicity were analysed for boron and other nutrients.
• Samples were obtained from sites throughout the cropping districts of South Australia.
• In plants with characteristic foliar symptoms, the concentration of boron alone was sufficient to account for the crop disorder.
• The mean concentration in affected plants was 151 mg/kg and in control plants 23 mg/kg.
• Slight accumulations of sodium and chloride were associated with the disorder, along with slightly lower calcium concentrations.
• The nutrient balance was consistent with association of the toxicity with sodic and saline soils.
• Severe boron toxicity is widespread in barley crops in South Australia.