Neofabraea actinidiae

Early symptoms appear as small, circular, or irregular depressed spots on the bark, which eventually darken as the underlying tissue begins to rot.

Small, cream-colored fruiting bodies of the fungus may emerge from the center of these lesions, especially under high humidity conditions.

Branches affected by Neofabraea actinidiae often exhibit premature leaf yellowing and wilting, indicating that the vascular system is being compromised.

Fruit symptoms include the development of soft rot lesions, which can appear both in the field and after the fruit has been harvested and stored.

As the infection deepens, the bark may crack, and in some cases, gummy exudates may be observed flowing from the lesion sites on the stems.

The disease is caused by the fungus Neofabraea actinidiae, an ascomycete pathogen that primarily affects the woody tissues of the actinidia plant.

The fungus typically invades the host through bark fissures, pruning wounds, or sites damaged by insects, where it establishes its mycelium.

Once inside, the pathogen colonizes the vascular tissues and cambium, causing localized necrosis and structural damage to the branch or trunk.

The life cycle of the pathogen involves the production of conidia, which serve as the primary inoculum for spreading the disease within the orchard.

This fungus is known for its ability to persist in dead wood and debris, making it a recurring threat if orchard sanitation is neglected.

High humidity and moderate temperatures ranging between 15°C and 25°C are the primary environmental drivers for the rapid spread of the disease.

Rainy seasons provide the necessary moisture for the germination of fungal spores, facilitating their dispersal through water splashing and wind.

Orchards with poor ventilation due to excessive canopy density are more prone to infection because moisture remains on the foliage and bark for longer periods.

Plants that are weakened due to improper nutrition or environmental stress show less resistance to colonization by this specific pathogen.

Mechanical damage caused by hail, frost, or improper pruning equipment creates entry points that significantly increase the susceptibility of the actinidia plant.

The damage caused by Neofabraea actinidiae can lead to significant branch dieback, weakening the structural integrity of the plant over time.

In addition to structural damage, the fruit rot associated with this fungus leads to substantial economic losses by reducing the marketable yield.

The infection significantly impairs the plant's ability to survive winter, often leading to increased mortality following severe cold events.

Continuous presence of the disease in an orchard can lead to an accumulation of inoculum, necessitating long-term chemical management programs.

If not contained, the disease can lead to the gradual decline and eventual loss of the entire kiwifruit orchard, requiring replanting and major investment.

The foundation of effective management involves strict sanitation practices, including the regular removal and destruction of all infected wood and debris.

All pruning cuts should be sealed with appropriate wound dressing products to prevent the entry of fungal spores into the fresh plant tissue.

• Apply copper-based fungicides in the early spring as a preventive measure.
• Use systemic fungicides during periods of high disease pressure and wet weather.
• Implement a balanced fertilization program to maintain optimal plant vigor.
• Maintain proper canopy density to ensure good airflow and reduce leaf wetness duration.
• Sterilize all pruning equipment between trees to avoid cross-contamination.

Regular orchard scouting is essential to identify new infections early, allowing for targeted pruning before the pathogen spreads further.

Choosing healthy planting stock from reliable nurseries is a crucial step in preventing the introduction of this disease into new actinidia orchards.