Common Citrus Tree Leaf Problems: Causes and Solutions

Citrus trees are prized for their lush, green leaves, but when they start showing signs of distress, it can be worrying for any grower. Yellowing, curling, and spotting on leaves are common issues faced by citrus tree owners. These problems can be caused by several factors, including nutrient deficiencies, pests, diseases, or environmental stress. Understanding the cause of your tree’s leaf problems is key to addressing and correcting them.

1. Yellowing Leaves (Chlorosis)

One of the most common problems with citrus trees is yellowing leaves, known as chlorosis. This condition typically arises when the tree is not getting the nutrients it needs, particularly iron or nitrogen. Here are the primary causes:

• Iron Deficiency: Citrus trees, especially in alkaline soils, can suffer from iron deficiency, causing leaves to turn yellow with green veins (interveinal chlorosis).
• Overwatering: Excess water can suffocate the roots, reducing their ability to take up nutrients, leading to yellow leaves.
• Pests: Aphids, mealybugs, and scale insects can suck sap from leaves, leading to nutrient deficiencies and yellowing.

To address yellowing leaves, treat nutrient deficiencies by applying a balanced fertilizer such as Complete Grow Citrus Fertiliser, and ensure your tree is not being overwatered. Iron chelate can also be applied to correct iron deficiency.

2. Curling or Distorted Leaves

Citrus leaves can curl or become distorted due to several factors:

• Environmental Stress: Citrus trees are sensitive to extreme weather conditions like high heat, strong winds, or cold temperatures. These stresses cause the leaves to curl as the tree tries to conserve moisture.
• Pest Infestation: Aphids and other sap-sucking pests can distort leaves. Check the underside of leaves for insects.
• Fungal Diseases: Fungal infections like Phytophthora can cause curling and browning of the leaves.

To manage curling leaves, start by inspecting for pests and treat accordingly with neem oil or insecticidal soap. Ensure the tree is not exposed to extreme weather and water properly to avoid stress. Apply a fungicide if fungal disease is suspected.

3. Premature Leaf Drop

Citrus trees may shed leaves prematurely due to stress from environmental factors or improper care:

• Watering Issues: Both overwatering and underwatering can cause premature leaf drop. The tree may drop leaves as a survival mechanism to conserve energy.
• Fertilizer Problems: Over-fertilizing, especially with nitrogen-rich fertilizers, can lead to excessive growth and premature leaf drop.
• Temperature Extremes: Heat stress or frost can shock the tree, causing it to shed leaves.

Ensure that your citrus tree is not stressed by overwatering or underwatering, and avoid excessive fertilizing. Provide shade during hot spells and protect the tree from frost. Regularly inspect the tree for signs of stress or damage and address them promptly.

4. Blackened or Brown Leaves

If you notice blackened or brown leaves, it could be due to:

• Fungal Infections: Black spots or brown edges can be a sign of fungal infections like Alternaria or Septoria.
• Herbicide Damage: Overexposure to herbicides can cause leaf burn and blackening. Always follow label instructions when using herbicides.

Prune off the affected leaves and apply a fungicide for fungal issues. For herbicide damage, prevent further exposure and avoid using chemicals near your tree.