European plum rust

European plum rust is a fungal disease caused by the pathogen Tranzschelia pruni-spinosae. As a specialized biotroph, this fungus infects various stone fruit trees, significantly disrupting the plant's physiological functions and reducing overall vitality by damaging the leaf tissue required for photosynthesis.

The primary hosts of this disease are members of the Prunus genus, particularly plums, prunes, apricots, peaches, and almonds. The infection is geographically widespread and can cause severe damage in orchards if not managed correctly, especially during seasons with high humidity and prolonged moisture on leaves.

Diagnostic symptoms include the appearance of small, yellow, or light green spots on the upper leaf surface during the mid-summer. As the fungus progresses, rusty-brown, powdery pustules form on the undersides of the leaves. Severe infections lead to premature defoliation, which causes significant stress to the tree and reduces its resilience to cold winter conditions.

The development of European plum rust is heavily influenced by environmental factors such as frequent rainfall, heavy dew, and moderate temperatures, which facilitate spore germination. The fungus survives the winter primarily as teliospores on fallen, infected leaves, which then serve as the primary inoculum source for the following season.

Effective management and prevention strategies include:

• Removing and destroying all fallen leaves during late autumn to reduce the inoculum level.
• Pruning trees to improve airflow and reduce humidity within the canopy.
• Applying copper-based fungicides in the early spring before bud break.
• Using systemic fungicides during the growing season if weather conditions favor disease outbreak.
• Maintaining optimal orchard hygiene to prevent cross-contamination.