Other Citrus Leaf Disorders

Dark greening of citrus leaves

Any unnatural coloration of citrus leaves needs to be investigated. A darker greening, while uncommon, could be a result of a nutrient deficiency.

While rarely seen, copper deficiency leaves are dark green and enlarged. Stems are also more slender than normal and appear flat and regular. Phosphorus deficient leaves can also become a darker green.

Growers should check using tissue analysis and apply the appropriate YaraVita product to the leaf to ensure supplies of the deficient nutrient are not limiting growth. 

Citrus leaf drop

Loss of leaf is a significant issue for citrus, slowing the growth of the tree and reducing fruit fill. Immediate action is needed to redress leaf drop. This includes checking for nutrient imbalances and revising fertilizer programs.

Poor tree vigor and leaf drop are common symptoms of poor calcium availability - defoliation occurs when the leaf Ca levels fall below 3%.

Growers should check using tissue analysis and apply the appropriate calcium nitrate product to the leaf to ensure supplies of the deficient nutrient are not limiting growth. 

Citrus leaf curl

Leaf curl on citrus trees is usually associated with insect infection in particular aphid infestations on young leaves. This curled appearance remains after the aphids have gone. Leaf miner damage also causes leaf curl.

While leaf curl is more often a result of insect damage, if this doesn't appear to be the case, check for deficiencies using tissue analysis. 

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 deficiencies 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. 

Citrus leaf spotting or blotching

As with leaf yellowing, any blotching or other irregularity in citrus leaf color needs to be checked. Pay particular attention to where the blotching occurs; note the symptoms and if in any doubt have tissues analyzed. This is likely to be a sign of nutrient deficiency.

Yellow and bronze blotches across the leaf margin can be symptoms of potassium deficiency. These can enlarge and the whole leaf becomes the same yellowish color.

Manganese deficiency is usually seen on young leaves as mottled yellowing of the leaf. The veins stay green while the interveinal areas are light green to yellow. In extreme cases white spots can also be found between veins. Take care as this can be confused with zinc deficiency.

Molybdenum deficiencies occur as interveinal, yellow spots and are mainly seen in the summer. They are the most severe on acid soils and can be cured by using foliar spray fertilizers.

First stage zinc deficiencies occur as chlorotic leaf spots - known as 'mottle leaf' and/or white interveinal areas with green veins. Take care as this can be confused with manganese deficiency. 

Citrus leaf bronzing

While most citrus trees will shed and lose leaves, any bronzing should be checked. Leaf bronzing is a typical symptom of phosphorus deficiency. Leaves are smaller than normal and older leaves die at the tips and margins. As the deficiency progresses, leaves become dark green. 

Growers should check using tissue analysis and apply the appropriate fertilizer to the leaf to ensure supplies of the deficient nutrient are not limiting growth.

Visit Nutrient Deficiencies in Citrus to learn more.