Citrus Leaf Yellowing
Any type of leaf yellowing in citrus needs investigation. Loss of green color indicates poor growth and tree productivity will suffer as a result.
While nitrogen dificiencies are rare, when leaf N contents drop below 2% DM, the entire leaf becomes light green to yellow and can drop.
Symptoms of iron chlorosis, or yellowing in citrus, appear first on young shoots. Under severe deficiency, leaves almost turn white, are stunted, and drop prematurely. Lemons are more sensitive to iron deficiency than oranges and grapefruit.
Deficiency is best treated by soil application with chelated forms of iron. Foliar spray fertilizers will alleviate transient iron deficiencies.
Magnesium deficient citrus leaves have tip and margin interveinal chlorosis while the base of the leave remains green. Symptoms are most common on cultivars with a large number if seeds.
Sulfur deficiency is similar to that for nitrogen - the youngest leaves turn completely yellow.
See also Citrus Leaf Blotching.
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