Citrus scab

Elsinoe fawcettii is a fungal pathogen that causes citrus scab, a common disease affecting citrus crops. The disease primarily affects the fruit, leaves, and twigs of citrus trees, leading to cosmetic damage and potential economic losses. Here is an overview of Elsinoe fawcettii, its appearance, identification, and management:

1. Appearance:

• Lesions: Citrus scab is characterized by the development of scaly, corky lesions on the surface of citrus fruit, leaves, and twigs. The lesions appear as raised, rough, and wart-like structures.

• Fruit Symptoms: On citrus fruit, scab lesions can lead to blemishes, affecting the appearance and marketability of the fruit. The lesions are often more prominent on the peel but may also occur on the flesh.

• Leaf and Twig Symptoms: Scab lesions on leaves and twigs can lead to distortion and malformation. The severity of symptoms can vary depending on environmental conditions and citrus cultivars.

2. Identification:

• Microscopic Features: Laboratory identification involves the examination of fungal structures, including spore-producing structures (pycnidia) and spores (conidia), under a microscope. The conidia are typically lemon-shaped and help distinguish Elsinoe fawcettii from other pathogens.

• Symptom Recognition: Field identification is based on recognizing the characteristic scaly lesions on citrus fruit, leaves, and twigs. The presence of these lesions, especially during wet or humid conditions, is indicative of citrus scab.

3. Management:

• Fungicide Applications: Fungicides are commonly used to manage citrus scab. Copper-based fungicides and other fungicides with activity against Elsinoe fawcettii are applied during critical periods, especially during the growing season and fruit development.

• Pruning: Proper pruning practices, such as removing infected twigs and branches, can help reduce the inoculum source and promote air circulation within the citrus canopy.

• Sanitation: Remove and destroy fallen leaves and fruit with scab lesions to reduce the overwintering of the pathogen in the orchard.

• Resistant Varieties: Planting citrus varieties that exhibit some level of resistance to Elsinoe fawcettii can be an effective strategy.

• Cultural Practices: Implementing good cultural practices, such as adequate spacing between trees, can help reduce humidity within the canopy, creating an environment less favorable for disease development.