Botryosphaeria canker

Botryosphaeria canker is a dangerous fungal disease caused by pathogens of the genus Botryosphaeria (most notably Botryosphaeria dothidea). This pathogen belongs to the Ascomycetes class and is a widespread disease of woody plants, causing bark necrosis, dieback of branches, and general degradation of the host's tissues.

The disease primarily affects perennial woody plants and shrubs. Pome and stone fruit trees (apple, pear), nut crops, as well as various ornamental species such as juniper, thuja, cypress, and many broadleaf trees like oak are frequently affected by Botryosphaeria infections.

The main symptoms of the infection include the appearance of depressed or sunken areas of bark, which eventually crack. Small, black, pimple-like structures — pycnidia (the fungus's spore-bearing organs) — can often be observed on the affected tissue. As the disease progresses, leaves wilt, and branches or entire limbs die, which can lead to the total death of the plant if left unchecked.

The development of the fungus is favored by unfavorable weather conditions, particularly drought, high temperatures, and extreme fluctuations in humidity. Infection typically occurs through mechanical bark wounds, sunscald, frost cracks, or improper pruning cuts, which serve as entry points for fungal spores into the plant's vascular system.

The severity of the disease lies in the disruption of sap flow, which weakens the tree's immune system and leads to premature tree loss in orchards and landscapes. Effective protection requires a multi-faceted approach:

• prompt removal and disposal of infected branches;
• disinfection of pruning tools after every cut;
• treatment of wounds with pruning paint or appropriate fungicides;
• maintaining proper irrigation to prevent drought stress;
• preventive application of copper-based fungicides during the dormant season.