Diplodina maple blight

The causal agent of this disease is the micromycete Diplodina acerina, which belongs to a group of fungi responsible for infectious bark and branch necrosis in woody plants. This parasite primarily attacks weakened specimens, entering through mechanical damage to the bark, cracks, or frost wounds.

The primary host for this disease is the maple (Acer), including Norway maple and other species. The infection affects branches and stems, leading to the disruption of normal nutrient and water transport within the plant tissues.

The key symptom is the appearance of elongated, sunken spots or necrotic zones on the bark of branches and trunks. Over time, the affected areas of the bark crack and die. In the affected areas, fruiting bodies of the fungus (pycnidia) form, appearing as small black dots protruding above the surface of the bark.

The development of the fungus is favored by high air humidity and moderate temperatures, typical of the spring and autumn seasons. Spore dispersal occurs through raindrops, wind, or insects. Densely planted areas and the lack of sanitary pruning create an ideal environment for the progression of the necrosis.

The harm caused by the disease involves the gradual dieback of branches, which leads to a loss of aesthetic value and the eventual drying of the entire tree. In cases of severe stem infection, the tree may perish within a few seasons, making a comprehensive approach to disease management essential.

Control measures include the following actions:

• Prompt removal and burning of affected branches.
• Disinfection of pruning wounds with wound dressing or fungicides.
• Maintaining tree health through regular fertilization and watering.
• Spraying the canopy with copper-based preparations at the beginning of the growing season.