Phomopsis cane and leaf spot

The pathogen responsible for this disease is the fungus Diaporthe neoviticola, which induces the condition commonly referred to as Phomopsis cane and leaf spot. This fungus is a significant threat to viticulture, as it overwinters in the infected bark and wood, ready to release spores as soon as temperatures rise in the spring.

The disease primarily affects grapevines (Vitis vinifera). It colonizes green tissues including shoots, leaves, petioles, and clusters. The infection is particularly damaging to young, rapidly developing tissue, which acts as the main entry point for the pathogen at the beginning of the growing season.

The initial symptoms are characterized by small black spots surrounded by a chlorotic halo on shoots and leaves. As the infection progresses, these spots expand, causing the bark to crack and the shoots to become deformed and brittle. In severe cases, the infected shoots may snap under the pressure of wind or crop load.

The spread of the fungus is heavily dependent on wet, cool weather conditions during the early growth stages. Rain splashes serve as the primary vector, spreading the spores from infected overwintering sites to new growth. Temperatures between 10°C and 20°C combined with high relative humidity create an ideal environment for spore germination and infection.

The economic impact of this disease includes substantial yield losses due to flower cluster blight and reduced fruit quality. Furthermore, the infection affects the long-term vigor of the vine, as cumulative damage to the canes leads to reduced cold hardiness and eventually the decline or death of the entire plant if left unmanaged.

• Applying preventive copper-based fungicides at the bud-burst stage.
• Removing and destroying infected wood during dormant pruning.
• Improving canopy management to enhance airflow and leaf drying.
• Using clean, disease-free nursery stock for new plantings.
• Regular scouting for early symptoms during wet spring weather.