Role of Iron in Citrus Production

In citrus production, iron acts as a catalyst in oxidation/reduction reactions; is involved in respiration; photosynthesis; and the reduction of nitrate and sulfate. It is also a cofactor in many enzymes.

Iron effect at growth stages

Stage Iron effect
Fruit Set To maintain fruit yield and quality should be applied with each leaf flush
Post Harvest When needed for post harvest foliage flush
See more on Citrus Growth Stages.

General guidelines for Iron application

The form of applied iron used to correct any deficiency is important. Chelates are more stable across a wide range of soil pHs and should be the preferred form to correct long-standing annual deficiencies, particularly on calcareous soils. Trials with chelates confirm that soil applications are more effective and provide bigger yield responses than foliar applications.

Iron deficiencies in Citrus

Symptoms of iron chlorosis appear first on young shoots. Under severe deficiency, leaves almost turn white, are stunted, and drop prematurely. Fe-deficiency is most common on alkaline (high pH), especially those with free lime in the topsoil (e.g. Spain and Australia), waterlogged soils and those of low organic matter (e.g. sand-soaks in Florida). Deficiency is best treated by soil application with chelated forms of iron. Foliar sprays will alleviate transient iron deficiencies. Lemons are more sensitive to iron deficiency than oranges and grapefruit. Use tissue analysis to check for deficiencies.