Chlorosis on young citrus leaves: the main cause is iron deficiency
In many citrus growing areas, intense yellowing is occasionally observed on young leaves, with characteristic retention of the green colour along the ribs. This phenomenon, known as midvein chlorosis, is an indicative symptom of iron (Fe) deficiency, which mainly affects new growth due to the limited mobility of the element in the plant.
Iron is essential for the synthesis of chlorophyll and the proper functioning of photosynthesis. Its deficiency directly affects the metabolic activity and growth of the plant.
Soil and pH: the determinants of absorption
Iron deficiency in citrus trees is more often attributed to an inability to absorb iron than to an actual deficiency in the soil. Soils with a high pH (alkaline or calcareous) limit the availability of iron, even when the element is present in sufficient quantities. This phenomenon is referred to as ‘inactive iron’.
Excessive presence of competing elements, such as phosphorus, copper or manganese, and conditions of limited aeration of the rootstock due to excessive irrigation or poor drainage are also aggravating factors.
Effect on production
Iron deficiency is not just a visual phenomenon. It negatively affects vegetative growth, flowering and fruit set. Affected trees show reduced leaf area, increased defoliation and ultimately reduced production: fewer fruits, smaller size, reduced sugars and poorer taste.
Management of food poisoning
The most effective intervention is the application of iron in a stable chelated form, e.g. Fe-EDDHA, through the root system. Chelated forms remain active and absorbable even in high pH soils, unlike the simple forms (iron sulphate or ferric iron), which are rapidly bound.
Transfemoral iron application may temporarily improve the leaflet appearance, but it does not provide lasting restoration and requires frequent reapplication. In addition, it should be avoided during periods of intense sunshine to prevent foliar burns.
Soil analysis and foliar diagnostics
Rational management starts with a correct diagnosis. Soil analysis determines the availability of iron and its general physico-chemical properties (e.g. pH), while foliar diagnostics confirms the actual nutritional status of the plant.
Measurement targeting reduces unnecessary applications, reduces costs and enhances the effectiveness of the intervention.
Tips
-Prefer chelated forms of iron (Fe-EDDHA) for high pH soils.
-Limit the use of phosphorus and manganese to equilibrium levels.
-Improve the drainage and aeration of the rhizosphere.
-Apply iron proactively to sensitive varieties and soils with a history of chlorosis.
Conclusion
Citrus trees are particularly susceptible to iron deficiency, especially when grown in calcareous environments. The combined use of high quality chelating agents, regular monitoring and crop prevention ensures healthy plants, stable production and improved fruit quality.
See all available citrus micronutrient formulations and learn more on the ZIKO micronutrient page.
