Abstract

Shurtleff, M. C. and B. J. Jacobsen. 1986. Iron chlorosis: its cause and control. Arbor Age 6 (3): 12-14.

Chlorosis, a yellowing of the plant leaf due to a lack of chlorophyll may be caused by a variety of factors. Among the more common causes are compacted soils, poor drainage, alkaline soils and nutrient deficiencies. Probably the most common cause is iron chlorosis, where iron is unavailable to the plant. Iron (Fe) is an essential element for plant growth, it is required for the formation of chlorophyll, the green pigments that capture light to produce food for the plant. Iron is also necessary for the proper functioning of many plant enzyme systems that influence respiration and plant metabolism. Chlorosis may develop because of unfavorable conditions for the utilization of iron in the plant or in the soil. Under neutral or alkaline conditions at a soil reaction (pH) above 6.5 to 6.7 iron changes into insoluble forms and becomes unavailable for uptake and utilization by the plants. Iron chlorosis can be controlled when plants are supplied with available iron. The iron may be sprayed onto the chlorotic foliage, introduced into the trunk or added to the soil. The most lasting results are obtained through treating the soil.

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