The role of Fe DTPA (Diethylenetriaminepentaacetic acid) in the occurrence of a specific physiological disorder affecting the leaves of cutting geranium was investigated. Industry reports indicate that affected leaves have excessively high concentrations of Fe and sometimes Mn. Symptoms of the disorder first affect maturing leaves, and may in severe cases affect immature leaves. Symptoms progress from marginal/interveinal chlorosis and necrosis, to affect whole leaf necrosis. Rooted cuttings were grown in a soil-less peat based media, with Fe DTPA concentrations of 1, 5, 15, and 20 ppm. Iron and manganese leaf concentrations were significantly higher in symptom than in non-symptom tissue and increased as Fe DTPA treatment level increased. As Fe DTPA treatment level increased there was a significant increase in dry weight of symptom tissue and a decrease in non-symptom tissue dry weight. Plants grown in media amended with dolomite (pH> 5.8) had similar degrees of symptom occurrence compared to plants grown in unamended media (pH ≈ 5.4).
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