If you’re worried because your orange tree’s leaves are turning yellow, don’t panic! There are many reasons why this can happen, and most of them can be fixed.

What Causes Yellowing Leaves on Orange Trees?

There are four main causes of yellowing leaves on orange trees:

• Disease: Fungal diseases like Phytophthora gummosis, Phytophthora root rot, and Armillaria root rot can all cause leaves to turn yellow.
• Pests: Pests like scale, mites, and nematodes can also damage leaves and cause them to turn yellow.
• Nutrient deficiency: A lack of iron in the soil can also cause leaves to turn yellow.
• Environmental/cultural: Poor watering practices, extreme weather conditions, and lack of sunlight can all stress orange trees and cause their leaves to turn yellow.

How to Treat Yellowing Leaves on Orange Trees

The treatment for yellowing leaves on orange trees depends on the cause.

Disease

• Phytophthora gummosis: Keep the trunk dry, scrape away diseased bark, and remove any branches that touch the ground.
• Phytophthora root rot: Cut irrigation to allow the trunk to dry. If the damage is severe, remove the tree and fumigate before replanting.
• Armillaria root rot: Remove and burn infected trees and those surrounding the infected area. Fumigate the site before replanting.

Pests

• Scale: Use parasitic wasps to control scale.
• Mites: Use oil spray or wash the leaves with soapy water.
• Nematodes: Buy only resistant rootstock.

Nutrient deficiency

• Iron deficiency: Apply foliar nitrogen, such as urea, to increase set and yield.

Environmental/cultural

• Proper watering: Water orange trees deeply and regularly, especially during hot, dry weather.
• Avoid over-fertilizing: Too much fertilizer can damage orange trees and cause their leaves to turn yellow.
• Protect from extreme weather: Cover orange trees or move them to a protected area during cold snaps or high winds.
• Remove fallen fruit: Remove any fallen fruit or fruit that is rotting on the limb to prevent attracting fungal or bacterial diseases.

Prevention is Key

The best way to prevent yellowing leaves on orange trees is to practice good gardening habits, such as:

• Proper irrigation: Water orange trees deeply and regularly, especially during hot, dry weather.
• Fertilization: Fertilize orange trees according to the manufacturer’s instructions.
• Pruning: Prune orange trees regularly to remove dead or diseased branches.
• Pest control: Monitor orange trees for pests and treat them promptly.
• Disease control: Keep the area around orange trees clean and free of debris.

By following these tips, you can keep your orange trees healthy and prevent their leaves from turning yellow.

Additional Tips

• If you’re not sure what’s causing the yellowing leaves on your orange tree, contact a certified arborist or horticulturalist for help.
• Be patient! It may take some time to see results from your treatment.
• Don’t give up! With proper care, you can get your orange tree back to health and enjoy its beautiful green leaves for years to come.