Toxic concentrations of iron and manganese in leaves of Phaseolus vulgaris L. growing on freely‐drained soils of pH 6.5 in Northern Tanzania

A bronzing symptom of trifoliolate leaves of Phaseolus vulgaris is described which has been found to be widespread on the southern slopes of the Meru and Kilimanjaro massifs in northern Tanzania. The symptom occurred on plants growing on freely draining soils of moderate pH and has led to complete loss of yield of badly affected plants. Leaves with the bronzing symptom contained large concentrations of iron (>3080 mg/kg) and manganese (>760 mg/kg) considered to be toxic in Phaseolus plants.