Esca is a significant grapevine disease that affects vineyards worldwide. It’s caused by a combination of fungi, including Phaeoacremonium spp., Phaeomoniella chlamydospora, and other associated pathogens. This disease complex primarily targets the woody tissues of grapevines, leading to decline and death if left unmanaged. Here’s an overview of Esca disease, its symptoms, recommendations, causes, and preventive measures:

Symptoms:

1. Foliar Symptoms:
   • Chlorosis (yellowing) of leaves, typically between veins.
   • Browning or necrosis (death) of leaf tissue, often in a wedge-shaped pattern.
   • Reduction in leaf size and premature defoliation.
2. Wood Symptoms:
   • Internal necrosis (cell death) in the wood, often visible upon cutting or peeling back the bark.
   • Black streaking or discoloration in the wood.
   • Formation of white or brown mycelial mats under the bark.
3. Other Symptoms:
   • Decline in vine vigor, with reduced growth and productivity.
   • Delayed bud break and poor shoot development.
   • Increased susceptibility to secondary infections and pests.

Recommendations:

1. Cultural Practices:
   • Use certified disease-free planting material to establish new vineyards.
   • Prune vines carefully during dormancy to remove infected wood and minimize disease spread.
   • Improve vineyard airflow and reduce humidity to create less favorable conditions for fungal growth.
   • Avoid excessive nitrogen fertilization, as it can promote disease development.
2. Chemical Control:
   • Application of fungicides may provide some control, although they are generally not considered highly effective against Esca disease.
   • Use of systemic fungicides injected into the trunk may help protect healthy tissues from infection.

Causes:

1. Fungal Pathogens: Esca disease is primarily caused by fungi, including Phaeoacremonium spp. and Phaeomoniella chlamydospora, which infect grapevines through wounds and pruning cuts.
2. Environmental Factors: Environmental stressors such as drought, heat, and excessive moisture can weaken vines and predispose them to infection by Esca pathogens.
3. Cultural Practices: Improper vineyard management practices such as over-pruning, excessive irrigation, and poor soil drainage can exacerbate Esca disease.

Preventive Measures:

1. Sanitation: Practice good vineyard hygiene by removing and destroying infected wood and pruning debris to reduce inoculum levels.
2. Resistant Varieties: Consider planting grapevine varieties known to be less susceptible to Esca disease, although complete resistance is rare.
3. Vineyard Management: Implement cultural practices aimed at reducing stress on grapevines and promoting overall vine health, including balanced nutrition, appropriate irrigation, and careful pruning.

It’s important to note that Esca disease is complex and challenging to manage. Integrated approaches combining cultural practices, chemical control, and resistant varieties are often necessary for effective disease management. Additionally, regular monitoring and early detection of symptoms are critical for timely intervention and minimizing the impact of Esca disease in vineyards.