What is Scab Disease?

Scab disease is a serious fungal infection affecting citrus trees. This disease, primarily caused by the fungus Elsinoe fawcettii, leads to noticeable blemishes and deformities on various parts of citrus plants.

Impact on Citrus Varieties

Scab is known to impact a wide range of citrus types. Key affected species include:

• Sour Orange: Highly susceptible.
• Carrizo Citrange: Also frequently targeted.
• Rough Lemon: Prone to infection.
• Rangpur Lime: Another common host.
• Grapefruit: Elsinoe fawcettii is also known to affect grapefruits

Symptoms and Manifestations

The disease is marked by characteristic symptoms, primarily on the leaves, stems, and fruit. Specifically, on leaves:

• Scab Pimple: A combination of host and fungal diseases, leading to raised lesions.
• Deformed Leaves: The leaves can become distorted and misshapen due to the fungal attack.

Causes

The primary cause of citrus scab is the fungal pathogen, Elsinoe fawcettii. This fungus thrives in moist and humid conditions, making such environments conducive to its spread.

Management and Prevention

While no cure exists for citrus scab, several strategies can help in managing and preventing its spread:

• Fungicide Applications: Regular applications of appropriate fungicides during critical periods of plant growth can help protect the plants.
• Pruning: Removing infected parts of the tree helps reduce inoculum source, although it will not eradicate the disease, as wind-borne spores can reinfect trees.
• Planting Resistant Varieties: Selecting citrus varieties known for their resistance to scab may help minimize infection risk in the long term.