Cytospora ceratophora

The disease is caused by the fungus Cytospora ceratophora, a well-known pathogen responsible for cytospora canker. This fungus functions as a wound parasite, infecting the host through bark injuries and eventually colonizing the cambium and xylem tissues, which leads to tissue death.

The primary hosts of this pathogen are stone fruit trees, including cherries, apricots, and peaches. The infection is particularly damaging to trees that have been weakened by environmental stressors such as drought, winter frost injuries, or mechanical damage from improper pruning practices.

Symptoms initially appear as localized discolorations on the bark, which later turn into sunken, necrotic lesions. As the fungus develops, small, erupting structures called pycnidia form on the surface of the dead bark, releasing spores during periods of high humidity and rainfall.

The development of Cytospora ceratophora is favored by stagnant moisture and high humidity, which facilitate spore germination. The fungus spreads rapidly in orchards where trees have suffered from sunscald or winter bark splits, as these injuries provide immediate entry points for the fungal spores to establish infection.

Effective management requires a proactive approach aimed at preventing the entry and spread of the fungus. Key measures include:

• Prompt removal and disposal of all dead or infected branches.
• Applying wound dressings to all pruning cuts to prevent colonization.
• Maintaining tree vigor through proper irrigation and balanced fertilization.
• Regular inspection of the bark for early signs of canker formation.