Cytospora canker

Cytospora cincta is a pathogenic fungus that causes Cytospora canker, a severe disease primarily affecting stone fruit trees. This fungal infection attacks the bark and cambium layer, leading to localized necrosis and eventual death of the affected plant parts.

The disease frequently targets species such as apricots, cherries, peaches, and plums. The pathogen acts as a wound parasite, meaning it primarily enters the tree through physical damage, including pruning wounds, frost cracks, or sunscald, especially when the host tree is already under environmental stress.

Symptoms typically include sunken, discolored patches on the bark, often accompanied by gumming (gummosis). As the disease progresses, the bark may peel away, revealing necrotic wood underneath. During moist weather, characteristic orange or yellowish spore-producing structures appear on the surface of the infected bark.

The development of Cytospora cincta is highly dependent on humidity and temperature levels. The fungus survives in dead or diseased woody tissue and produces spores that are easily spread by wind and rain splashes. Damp spring conditions are particularly conducive to the germination of spores and the initiation of new infections.

The impact of this disease is significant, often resulting in the loss of major branches or the death of the entire tree. Control strategies focus on strict sanitation, such as removing infected branches well below the margin of infection, protecting trees from physical trauma, and applying copper-based fungicides to seal pruning wounds and prevent colonization.