Iron (Fe) deficiency, like magnesium (Mg) deficiency, is involved in the failure of plants to produce sufficient chlorophyll, with the result that Fe and Mg symptoms can be similar for many plants. In both deficiencies, new leaves are affected first and become chlorotic, but with Fe deficiency, the contrast between the green of the old leaves and the chlorosis of the new growth is more marked than for any other relatively immobile element.

The nature of the chlorosis in the case of Fe deficiency is characteristic for cereals. Wheat leaves show a longitudinal interveinal chlorosis, resulting in a pattern of alternate green and yellow striping, and this pattern is more regular for Fe deficiency than for Mg or manganese (Mn) deficiencies.

Under severe Fe deficiency, the new growth may appear completely devoid of chlorophyll and turn white. These new leaves remain chlorotic for some time, unlike other deficiencies where necrosis can set in even though a portion of the leaf remains green.

In the field, Fe deficiency is seen most on calcareous soils or after heavy applications of lime. Mn deficiency can also be induced under these conditions, but symptoms differ as stated above. Moreover, Fe-deficient plants remain relatively erect, while Mn-deficient plants are generally floppy. Plant growth in compacted areas (i.e. wheel tracks) may be normal. Without compacted areas, there is usually general yellowing over the field, unless there are limestone outcrops to which Fe deficiency is restricted.