Coral spot fungus

Coral spot fungus (Nectria cinnabrarina) is an ascomycete fungus belonging to the Nectriaceae family. As a facultative parasite, it predominantly infects woody plants that have been weakened by environmental stress, drought, or mechanical damage. It is classified as a necrotrophic pathogen, causing extensive damage to plant tissues by decomposing wood and bark.

This pathogen affects a wide range of hosts, including deciduous trees and shrubs such as apple, cherry, currant, and maple. The disease manifests as the development of conspicuous coral-pink to reddish-orange pustules on the bark surface. These structures represent the fungal conidia, which later mature into darker, globose perithecia that release spores during wet weather conditions.

The life cycle begins when fungal spores enter the host through open wounds, such as those caused by pruning, winter frost cracks, or insect damage. Once inside, the mycelium invades the cambium layer, leading to localized necrosis and eventual death of the affected branch. The fungus can survive in dead wood for long periods, acting as a reservoir for further infections within the plantation.

Environmental factors play a critical role in the prevalence of coral spot. High humidity levels and rainfall facilitate the rapid spread of spores via splashes and wind dispersal. Dense plantings with poor air circulation often experience higher disease pressure. Therefore, maintaining tree vigor through proper fertilization and watering is the first line of defense against colonization.

Management strategies focus on strict sanitation. Infected branches must be pruned well back into healthy wood, ensuring the removal of all discolored tissues. All tools must be disinfected after working on affected plants to prevent cross-contamination. Applying protective fungicides containing copper or other active ingredients to large pruning wounds helps to inhibit spore germination and protects vulnerable areas from further infection.